SYSTEMS AND METHODS FOR PROCESSING HYDROGEN AND HYDROGEN

CARRIERS

CROSS REFERENCE

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 63/417,632, filed October 19, 2022, and U.S. Provisional Patent Application No. 63/419,593, filed October 26, 2022, each of which are incorporated herein by reference in their entirety for all purposes.

BACKGROUND

[0002] As the world economy aims to decarbonize by 2050 or sooner, interest in zero-carbon (or carbon-neutral) energy systems has grown rapidly. Scalable zero-emission fuels (SZEFs; chemical fuels that are produced using renewable, zero-carbon energy) are of particular interest, since SZEFs can replace fuels used in hard-to-decarbonize sectors.

SUMMARY

[0003] Hydrogen, being a scalable zero-emission fuel (SZEF), can be leveraged as a clean energy source to power various systems. Hydrogen can provide a distinct advantage over other types of fuel such as diesel, gasoline, or jet fuel, which have specific energies of about 45 megajoules per kilogram (MJ/kg) (heat), or lithium-ion batteries, which have a specific energy of about 0.95 MJ/kg (electrical). In contrast, hydrogen has a specific energy of over 140 MJ/kg (heat). As such, 1 kg of hydrogen can provide the same amount of energy as about 3 kg of gasoline or kerosene. Thus, hydrogen as a fuel source can help to reduce the amount of fuel (by mass) needed to provide a comparable amount of energy as other traditional sources of fuel. Further, systems that use hydrogen as a fuel source (e.g., as a combustion reactant) generally produce benign or nontoxic byproducts such as water while producing minimal or near zero carbon dioxide and nitrous oxide emissions, thereby reducing the environmental impacts of various systems (e.g., modes of transportation) that use hydrogen as a fuel source.

[0004] Recognized herein are various limitations with conventional systems and methods for processing hydrogen and/or mixtures of hydrogen and nitrogen to produce electrical energy. Commercially available fuel cells may exhibit degraded performance when processing hydrogen that is mixed with other gases (e.g., nitrogen and/or ammonia).

[0005] Hydrogen extracted from hydrogen carriers (e.g., ammonia, methanol) may comprise one or more other elements or compounds that can negatively impact fuel cell performance (e.g., conversion efficiency of aa lower heating value of the hydrogen carrier into electrical energy). Commercially available fuel cells may require separation of hydrogen from other materials before the hydrogen is fed to a fuel cell, which can be time consuming and resource intensive. [0006] The present disclosure provides systems and methods to address at least the abovementioned shortcomings of conventional systems for processing hydrogen to generate electrical energy. The present application relates generally to systems and methods for processing a source material (e.g., hydrogen and/or nitrogen) to produce energy (e.g., electrical energy). The energy may be used to power a system such as a vehicle. In some embodiments, the vehicle may comprise a drone, a light-duty vehicle, a heavy-duty vehicle, or a maritime vehicle. In some embodiments, the vehicle may be configured to be operated by a human or a computer. In some embodiments, the vehicle may be autonomous or semi-autonomous. The source material may comprise hydrogen and other elements or compounds. In some instances, the source material may comprise a mixture of hydrogen and nitrogen. The source material may or may not comprise other impurities. In some cases, the source material may be filtered before being provided to a fuel cell. Such filtering may be used to remove carbon monoxide and/or ammonia from the source material. The systems and methods of the present disclosure may be used to convert hydrogen mixtures into electrical energy without requiring filtration or purification of hydrogen mixtures to remove nitrogen and/or ammonia.

[0007] Additionally, recognized herein are various limitations with hydrogen storage and production systems currently available. Although hydrogen has a relatively high gravimetric density (measured in MJ/kg), fuel storage systems for compressed and liquefied hydrogen are often complex due to specialized storage conditions.

[0008] For example, storage of hydrogen may require tanks that can withstand high pressures (e.g., 350-700 bar or 5,000-10,000 psi), and/or may require cryogenic temperatures (since the boiling point of hydrogen at 1 atm of pressure is -252.8 °C). Additionally, hydrogen storage containers may be constructed using materials that are highly-specialized, costly, and difficult to develop, which may limit the ability to manufacture such hydrogen storage containers at a large scale.

[0009] Hydrogen carriers (HCs) are SZEFs that can be used as hydrogen storage vectors. Since HCs can be stored at significantly lower pressures (and/or higher temperatures) than hydrogen, HCs overcome some of the aforementioned shortcomings of hydrogen. Further recognized herein are various limitations of conventional HC processing systems, which generally have slow startup times, non-ideal thermal characteristics, suboptimal HC conversion efficiencies, and high weight and volume requirements.

[0010] Embodiments of the present disclosure are directed to HC reforming systems and methods. The present HC reforming systems and methods address the abovementioned shortcomings of conventional systems for storing and/or releasing hydrogen for utilization as a fuel.

[0011] The present HC reforming systems and methods may advantageously enable the reduction in carbon intensity of long-distance transportation where refueling can be difficult via other low carbon methods (for example, on trucking routes longer than 500 miles, or on transoceanic shipping routes). Over such long-distance routes, using batteries to power motors may entail excessively long recharging times and excessive weight and volume requirements, which reduces revenues for ship operators by decreasing the space available for cargo. Additionally, using compressed hydrogen or liquid hydrogen over such long-distance routes may not be feasible due to the specialized hydrogen storage conditions described previously, as well as the large volume requirements for the hydrogen storage tanks.

[0012] Additionally, the present HC reforming systems and methods may advantageously provide combustion fuel for self-heating (i.e., auto-thermal heating). In other words, the HC reformers may be heated by the combustion of hydrogen extracted from the HC reforming itself, as opposed being heated by combustion of hydrocarbons or HC (which undesirably emits greenhouse gases, nitrogen oxides (NO _X ), and/or particulate matter). By reforming HC into hydrogen, a separate tank may not be required for storing combustion fuel (e.g., hydrocarbons, hydrogen, HC, or ammonia).

[0013] Additionally, the present HC reforming systems and methods may advantageously provide a high purity reformate stream (e.g., at least about 99.9% H2/N2 mixture by molar fraction, or less than about 10 parts per million (ppm) of HC). This high purity is achieved by utilizing a filter (e.g., adsorbents) to remove unconverted or trace HC or CO2, and by high HC conversion efficiency (conferred by the effective design of the reforming reactor, as well as the reforming catalyst). The high purity reformate stream (H2/CO2 mixture, or H2 stream) may be consumed by a proton exchange membrane fuel cell (PEMFC) or other power generation device (e.g., internal combustion engine (ICE) or solid oxide fuel cell (SOFC)).

[0014] Additionally, the present HC reforming systems and methods may be simple to operate and may provide a high degree of safety. HCs may be provided to reformers using a single inlet (e.g., as opposed to a first inlet for a first reformer, a second inlet for a second reformer, and so on). Furthermore, a single stream of HC may pass through several reformers (e.g., first passing through a startup reformer, and then into a main reformer, or vice versa). This configuration may facilitate heat transfer from the reformers to the incoming HC stream (to vaporize or otherwise heat the incoming HC stream), and may increase the overall HC conversion efficiency (i.e., by nearly fully reforming the HC stream). In some embodiments, the HC flow rate may be controlled at the single inlet, and in the case of a major fault or dangerous event, the HC flow may be quickly shut off via the single inlet.

[0015] In one aspect, the present disclosure is directed to an anode gas diffusion layer (GDL) for a fuel cell. The fuel cell comprises an electrochemical circuit comprising an anode, a cathode, and an electrolyte between the anode and the cathode. The anode GDL comprises a porous material comprising one or more properties, wherein the one or more properties comprise a density, a pore size distribution, or particle size distribution. The one or more properties facilitate transport of hydrogen to the anode, and impede transport of nitrogen or water to the anode.

[0016] In some embodiments, the porous material is a carbon-based material.

[0017] In some embodiments, the pore size distribution is configured so that a size of pores of the porous material decreases or increases (1) from a first side of the anode GDL adjacent to outside the fuel cell (2) to a second side of the anode GDL adjacent to the electrolyte.

[0018] In some embodiments, an ammonia reformer is configured to react ammonia to generate a stream comprising nitrogen and hydrogen. The fuel cell is configured to receive the nitrogen and the hydrogen from the ammonia reformer.

[0019] In another aspect, the present disclosure is directed to a plurality of fuel cell stacks. The plurality of fuel cell stacks are electrically connected in a series arrangement. A physical property of at least one of the plurality of fuel cell stacks positioned upstream in the series arrangement is different from others of the plurality of fuel cell stacks positioned downstream in the series arrangement. The physical property comprises at least one of: (1) a fuel cell stack volume of each of the plurality of fuel cell stacks, or (2) an anode surface area of fuel cells in each of the plurality of fuel cell stacks.

[0020] In some embodiments, one or more dielectric partitions are positioned between at least two of the fuel cell stacks. The dielectric partition is configured to control a local current density between the two fuel cell stacks.

[0021] In some embodiments, the plurality of fuel cell stacks is configured to output a power of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilowatts.

[0022] In some embodiments, the plurality of fuel cell stacks is configured to output a power of at most about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilowatts. [0023] In some embodiments, the current density comprises at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amps per cm ² .

[0024] In some embodiments, the current density comprises at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amps per cm ² .

[0025] In another aspect, the present disclosure is directed to a cylindrical fuel cell comprising: an electrochemical circuit comprising a cylindrical anode, a cylindrical cathode, and a cylindrical electrolyte between the cylindrical anode and the cylindrical cathode. The cylindrical anode, the cylindrical cathode, and the cylindrical electrolyte are positioned annularly with respect to a longitudinal axis at a center of the cylindrical fuel cell. The cylindrical anode, the cylindrical cathode, and the cylindrical electrolyte are concentrically aligned with respect to the longitudinal axis. The cylindrical anode is adjacent to an inside surface of the fuel cell. The cylindrical cathode is adjacent to an outside surface of the fuel cell.

[0026] In some embodiments, the cylindrical anode comprises an anode current collector, an anode gas diffusion layer (GDL) and an anode catalyst.

[0027] In some embodiments, at least one of the anode current collector, the anode gas diffusion layer (GDL), and the anode catalyst comprise a thickness of at least 0.01 mm to at most about 10 centimeters.

[0028] In some embodiments, the cylindrical anode is positioned at a first radius with respect to the longitudinal axis, the cylindrical electrolyte is positioned at a second radius with respect to the longitudinal axis, the cylindrical cathode is positioned at a third radius with respect to the longitudinal axis, the second radius is greater than the first radius so that the cylindrical electrolyte is positioned farther from the longitudinal axis than the cylindrical anode, and the third radius is greater than the second radius and the first radius, so that the cylindrical cathode is positioned farther from the longitudinal axis than the cylindrical electrolyte and the cylindrical anode.

[0029] In some embodiments, a cathode feed duct is adjacent or at the outside surface of the fuel cell and in fluid communication with the cylindrical cathode, and the cathode feed duct is configured to provide at least oxygen to the cylindrical cathode.

[0030] In some embodiments, an anode feed manifold is in fluid communication with the inside surface of the fuel cell and the cylindrical anode, and the anode feed manifold is configured to provide a stream comprising at least hydrogen to the cylindrical anode.

[0031] In some embodiments, a mole fraction of the hydrogen in the stream comprises at least about 10, 20, 30, 40, 50, 60, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%. [0032] In some embodiments, a mole fraction of the hydrogen in the stream comprises at most about 10, 20, 30, 40, 50, 60, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%.

[0033] In some embodiments, the cylindrical fuel cell consumes or utilizes a mole fraction of the hydrogen in the stream of at least about 30, 40, 50, 60, 80, 85, 90, 95, or 99%.

[0034] In some embodiments, the cylindrical fuel cell consumes or utilizes a mole fraction of the hydrogen in the stream of at most about 30, 40, 50, 60, 80, 85, 90, 95, or 99%.

[0035] In some embodiments, an outer diameter of the cylindrical fuel cell cathode is at least about 1 millimeter, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm.

[0036] In some embodiments, an outer diameter of the cylindrical fuel cell cathode is at most about 1 millimeter, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm.

[0037] In some embodiments, a length of the cylindrical fuel cell is at least about 1 centimeter, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 50 cm, 1 m, 5 m, 10 m, 25 m, to or 50 meters.

[0038] In some embodiments, a length of the cylindrical fuel cell is at most about 1 centimeter, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 50 cm, 1 m, 5 m, 10 m, 25 m, to or 50 meters.

[0039] In some embodiments, a plurality of fuel cells each comprise the cylindrical fuel cell.

[0040] In some embodiments, the plurality of fuel cells comprises at least about 2, 4, 6, 8, 10, 50, 100, 500, 1000, 5000, 5000, or 10,000 fuel cells.

[0041] In some embodiments, the plurality of fuel cells comprises at most about 2, 4, 6, 8, 10, 50, 100, 500, 1000, 5000, 5000, or 10,000 fuel cells.

[0042] In some embodiments, a power output of the plurality of fuel cells is at least about 1 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 80 kW, 90 kW, 100 kW, 500 kW, 1 MW, 5 MW, 10 MW, 20 MW, 30 MW, 40 MW, 50 MW, 60 MW, 70 MW, 80 MW, 90 MW, or 100 MW.

[0043] In some embodiments, a power output of the plurality of fuel cells is at most about 1 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 80 kW, 90 kW, 100 kW, 500 kW, 1 MW, 5 MW, 10 MW, 20 MW, 30 MW, 40 MW, 50 MW, 60 MW, 70 MW, 80 MW, 90 MW, or 100 MW.

[0044] In some embodiments, one or more skids or plates are configured to secure, attach, or affix the plurality of fuel cells thereon. [0045] Another aspect of the present disclosure provides a non-transitory computer readable medium comprising machine executable code that, upon execution by one or more computer processors, implements any of the methods above or elsewhere herein.

[0046] Another aspect of the present disclosure provides a system comprising one or more computer processors and computer memory coupled thereto. The computer memory comprises machine executable code that, upon execution by the one or more computer processors, implements any of the methods above or elsewhere herein.

[0047] In one aspect, the present disclosure is directed to a method for reforming hydrogen carriers, comprising: (a) heating a first reformer to a first target temperature range; (b) directing HC to the first reformer to produce a reformate stream comprising hydrogen; (c) combusting the reformate stream to heat a second reformer to a second target temperature range; and (d) directing additional HC to the second reformer to produce additional reformate for the reformate stream. A first portion of the reformate stream is combusted to heat the second reformer while HC is being reformed in the second reformer.

[0048] In some embodiments, the first portion of the reformate stream is produced from the HC and/or the additional HC.

[0049] In some embodiments, the method further comprises processing a second portion of the reformate stream in a hydrogen processing module.

[0050] In some embodiments, the hydrogen processing module is a fuel cell.

[0051] In some embodiments, the reformate stream is directed through a hydrogen processing module prior to combusting the first portion of the reformate stream to heat the second reformer.

[0052] In some embodiments, the reformate stream from the first reformer is further reformed in the second reformer.

[0053] In some embodiments, the additional reformate from the second reformer is directed to the first reformer.

[0054] In some embodiments, the additional reformate from the second reformer is further reformed in the first reformer.

[0055] In some embodiments, the additional HC is directed to the first reformer before being directed to the second reformer.

[0056] In some embodiments, a pressure of the reformate stream is reduced when the reformate stream is directed through the hydrogen processing module compared to when the reformate stream is not directed through the hydrogen processing module. [0057] In some embodiments, a threshold amount of the reformate stream being directed to the hydrogen processing module results in substantially all of the reformate stream passing through the hydrogen processing module.

[0058] In some embodiments, an amount of HC directed to the second reformer is increased over a time period, the time period beginning when the second reformer is heated to the second target temperature range.

[0059] In some embodiments, the amount of HC directed to the second reformer is increased to a first target HC flowrate range.

[0060] In some embodiments, the reformate stream is directed to a hydrogen processing module when the first target HC flowrate range is reached.

[0061] In some embodiments, the HC flowrate is subsequently increased to a second target HC flowrate.

[0062] In some embodiments, the first portion of the reformate stream is combusted with oxygen, and the oxygen is provided in a substantially constant proportion relative to the hydrogen in the first portion of reformate.

[0063] In some embodiments, the method further comprises ceasing to perform (a)-(c) after the second reformer reaches the second target temperature range.

[0064] In some embodiments, the first portion of the reformate stream is controlled so that the second reformer maintains a temperature in the second target temperature range.

[0065] In some embodiments, combustion of the reformate stream maintains a temperature in the second reformer within the second target temperature range.

[0066] In some embodiments, the reformate stream is directed to a combustion heater in thermal communication with the second reformer so that the combustion heater receives substantially all of the reformate stream.

[0067] In some embodiments, a second portion of the reformate stream is vented or flared.

[0068] In some embodiments, the method further comprises increasing an amount of a second portion of the reformate stream that is processed in a hydrogen processing module.

[0069] In some embodiments, the method further comprises increasing the amount of HC directed to the second reformer to a first target HC flowrate range.

[0070] In some embodiments, the first reactor is electrically heated.

[0071] In some embodiments, the first reactor is heated using combustion of a fuel.

[0072] In some embodiments, the reformate stream is combusted with a stoichiometric excess of oxygen.

[0073] In some embodiments, the oxygen is sourced from air. [0074] In some embodiments, the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof. [0075] In some embodiments, the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[0076] In some embodiments, the HC comprises at least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof

[0077] In some embodiments, the first reformer comprises a first reforming catalyst and the second reformer comprises a second reforming catalyst.

[0078] In some embodiments, the first and second reforming catalysts are substantially the same catalyst.

[0079] In some embodiments, the first target temperature range and the second target temperature range at least partially overlap.

[0080] In some embodiments, the first target temperature range and/or the second target temperature range are between about 150 °C and about 800 °C.

[0081] In another aspect, the present disclosure is directed to a method for reforming hydrogen carriers, comprising: (a) directing HC to a reformer at an HC flow rate to produce a reformate stream comprising hydrogen; (b) combusting a first portion of the reformate stream with oxygen to heat the reformer; (c) processing a second portion of the reformate stream in a hydrogen processing module; and (d) based at least in part on a stimulus, performing one or more of: (i) changing the HC flow rate; (ii) changing a percentage of the reformate stream that is the first portion of the reformate stream; (iii) changing a percentage of the reformate stream that is the second portion of the reformate stream; or (iv) changing a percentage of the reformate stream that is vented or flared.

[0082] In some embodiments, at least two of (i)-(iv) are performed.

[0083] In some embodiments, at least three of (i)-(iv) are performed.

[0084] In some embodiments, all of (i)-(iv) are performed.

[0085] In some embodiments, the method further comprises changing an oxygen flow rate used for combustion to heat the reformer.

[0086] In some embodiments, the stimulus comprises a change in an amount of the hydrogen used by the hydrogen processing module.

[0087] In some embodiments, the stimulus comprises a temperature of the reformer being outside of a target temperature range. [0088] In some embodiments, the stimulus comprises a change in an amount or concentration of hydrogen carrier in the reformate stream.

[0089] In some embodiments, one or more of (i)-(iv) are performed so that: a temperature of the reformer is within a target temperature range; or at most about 10% of the reformate is vented or flared.

[0090] In some embodiments, one or more of (i)-(iv) are achieved for at least 95% of an operational time period.

[0091] In some embodiments, the operational time period is at least about 8 consecutive hours.

[0092] In some embodiments, the stimulus is based at least in part on an increase in an amount of the hydrogen used by the hydrogen processing module.

[0093] In some embodiments, the increased amount of hydrogen is a projected increased amount of hydrogen.

[0094] In some embodiments, based on the stimulus, one or more of: the HC flow rate is increased; the percentage of the reformate stream that is the first portion of the reformate stream is decreased; the percentage of the reformate stream that is the second portion of the reformate stream is increased; or the percentage of the reformate stream that is vented or flared is increased.

[0095] In some embodiments, the stimulus is based at least in part on a decreased amount of the hydrogen used by the hydrogen processing module.

[0096] In some embodiments, the decreased amount of hydrogen is a projected decreased amount of hydrogen.

[0097] In some embodiments, based on the stimulus, one or more of: the HC flow rate is decreased; the percentage of the reformate stream that is the first portion of the reformate stream is increased; the percentage of the reformate stream that is the second portion of the reformate stream is decreased; or the percentage of the reformate stream that is vented or flared is increased.

[0098] In some embodiments, the stimulus comprises (a) a discontinued processing of hydrogen using the hydrogen processing module and/or (b) a fault or malfunction of the hydrogen processing module.

[0099] In some embodiments, a plurality of hydrogen processing modules each comprise the hydrogen processing module, and the stimulus comprises (a) a discontinued processing of the hydrogen using one of the plurality of hydrogen processing modules and/or (b) a fault or malfunction in one of the plurality of hydrogen processing modules. [00100] In some embodiments, the percentage of the reformate stream that is the second portion of the reformate stream is changed to about zero percent in response to the stimulus.

[00101] In some embodiments, substantially none of the reformate stream is directed to the hydrogen processing module in response to the stimulus.

[00102] In some embodiments, substantially all of the reformate stream is directed to the second reformer and/or a combustion heater in thermal communication with the second reformer in response to the stimulus.

[00103] In some embodiments, a portion of the reformate stream is vented or flared in response to the stimulus.

[00104] In some embodiments, the stimulus is detected using a sensor.

[00105] In some embodiments, the stimulus is communicated to a controller.

[00106] In some embodiments, (d) is performed with the aid of a programmable computer or controller.

[00107] In some embodiments, (d) is performed using a flow control unit.

[00108] In some embodiments, the stimulus is a pressure.

[00109] In some embodiments, the pressure is increased in response to decreasing a flowrate to the hydrogen processing module.

[00110] In some embodiments, the pressure is a pressure of the reformate stream.

[00111] In some embodiments, the hydrogen processing module is a fuel cell.

[00112] In some embodiments, the reformer comprises an HC reforming catalyst.

[00113] In some embodiments, the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof.

[00114] In some embodiments, the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[00115] In some embodiments, the HC comprises at least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof.

[00116] In another aspect, the present disclosure is directed to a method for reforming hydrogen carriers, comprising: (a) directing HC to a reformer at an HC flow rate to produce a reformate stream comprising hydrogen; (b) combusting a first portion of the reformate stream with oxygen at an oxygen flow rate in a combustion heater to heat the reformer; (c) processing a second portion of the reformate stream in a hydrogen processing module; (d) measuring a temperature in the reformer or the combustion heater; (i) based at least in part on the measured temperature being outside of a target temperature range of the reformer or the combustion heater, performing one or more of: (i) changing the HC flow rate; (ii) changing the oxygen flow rate; (iii) changing a percentage of the reformate stream that is the second portion of the reformate stream; (iv) changing a percentage of the reformate stream that is the first portion of the reformate stream; or (v) changing a percentage of the reformate stream that is vented or flared out of the combustion heater.

[00117] In some embodiments, the hydrogen processing module is a fuel cell.

[00118] In some embodiments, the reformer comprises an HC reforming catalyst.

[00119] In some embodiments, at least two of (i)-(v) are performed.

[00120] In some embodiments, at least three of (i)-(v) are performed.

[00121] In some embodiments, at least four of (i)-(v) are performed.

[00122] In some embodiments, all of (i)-(v) are performed.

[00123] In some embodiments, the temperature is measured using a temperature sensor.

[00124] In some embodiments, the measured temperature is communicated to a controller.

[00125] In some embodiments, (i)-(v) are performed with the aid of a controller.

[00126] In some embodiments, (iii) and/or (iv) are performed using a flow control unit.

[00127] In some embodiments, (iii) and/or (iv) are performed by changing the second portion of reformate processed in the hydrogen processing module.

[00128] In some embodiments, the method further comprises, based at least in part on the measured temperature being greater than the target temperature range, performing one or more of: increasing the HC flow rate; decreasing the oxygen flow rate; increasing the percentage of the reformate stream that is the second portion of the reformate stream that is processed by the hydrogen processing module; decreasing the percentage of the reformate stream that is the first portion of the reformate stream; or increasing a percentage of the reformate stream that is vented or flared out of the combustion heater.

[00129] In some embodiments, increasing the percentage of the reformate stream that is the second portion of the reformate stream decreases the first portion of the reformate stream that is combusted.

[00130] In some embodiments, the hydrogen processing module is a fuel cell, and the first portion of the reformate stream is an anode off-gas that is directed from the fuel cell to the combustion heater. [00131] In some embodiments, decreasing the percentage of the reformate stream that is the first portion comprises decreasing the HC flow rate to the reformer to produce less hydrogen in the reformate stream.

[00132] In some embodiments, the hydrogen processing module is a fuel cell, and increasing the percentage of the second portion of the reformate stream that is processed by the hydrogen processing module increases an amount of power output by the fuel cell.

[00133] In some embodiments, the method further comprises, based at least in part on the measured temperature being less than the target temperature range, performing one or more of: decreasing the HC flow rate; increasing the oxygen flow rate; decreasing the percentage of the reformate stream that is the second portion of the reformate stream that is processed by the hydrogen processing module; increasing the percentage of the reformate stream that is the first portion of the reformate stream; or decreasing a percentage of the reformate stream that is vented or flared out of the combustion heater.

[00134] In some embodiments, decreasing the percentage of the second portion of the reformate stream that is the second portion increases the first portion of the reformate stream that is combusted.

[00135] In some embodiments, the hydrogen processing module is a fuel cell, and the first portion of the reformate stream is an anode off-gas that is directed from the fuel cell to the combustion heater.

[00136] In some embodiments, increasing the percentage of the reformate stream that is the first portion comprises increasing the HC flow rate to the reformer to produce more hydrogen in the reformate stream.

[00137] In some embodiments, the hydrogen processing module is a fuel cell, and decreasing the percentage of the second portion of the reformate stream that is processed by the hydrogen processing module decreases an amount of power output by the fuel cell.

[00138] In some embodiments, the method further comprises calculating a temperature difference between the temperature measured in the reformer or the combustion heater and a setpoint temperature within the target temperature range; and changing one or more of (i)-(v) by an amount that is based at least in part on the temperature difference.

[00139] In some embodiments, one or more of (i)-(v) are changed by a proportional factor.

[00140] In some embodiments, the proportional factor is different for each of (i)-(v).

[00141] In some embodiments, the method further comprises repeating (x) at a subsequent time point to obtain a subsequent temperature difference and repeating (y) to further change one or more of (i)-(v) by an amount that is proportional to the subsequent temperature difference. [00142] In some embodiments, (x) and (y) are repeated until the measured temperature is within the target temperature range. In some embodiments, the temperature measured in the reformer or combustion heater is a first temperature that is measured at a first time point, and the method further comprises: (q) at second time point subsequent to the first time point, measuring a second temperature of the reformer or the combustion heater; (r) calculating a time period between the first time point and the second time point; (s) calculating a temperature difference between the first temperature and the second temperature; and (t) changing one or more of (i)-(v) by an amount that is based at least in part on the time period and the temperature difference.

[00143] In some embodiments, the method further comprises repeating (q)-(t) until the measured temperature is within the target temperature range.

[00144] In some embodiments, the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof.

[00145] In some embodiments, the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[00146] In some embodiments, the HC comprises at least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof.

[00147] Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only illustrative embodiments of the present disclosure are shown and described. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[00148] The patent or application file contains at least one drawing executed in color.

Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[00149] The novel features of the invention are set forth with particularity in the appended claims. A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description that sets forth illustrative embodiments, in which the principles of the invention are utilized, and the accompanying drawings (also “Figure” and “FIG.” herein), of which:

[00150] FIG. 1 is a schematic diagram illustrating a fuel cell system, in accordance with some embodiments.

[00151] FIG. 2A is a plot illustrating the power output by a fuel cell when processing pure H2 compared to when processing an H2/N2 mixture.

[00152] FIG. 2B is a schematic diagram illustrating the diffusion of pure H2 compared to the diffusion of an H2/N2 mixture in a gas diffusion layer of a conventional fuel cell.

[00153] FIG. 3 is a schematic diagram illustrating performance improvements for anode channels comprising one or more cuts, in accordance with some embodiments.

[00154] FIG. 4 is a schematic diagram illustrating performance improvements for anode channels comprising one or more cutouts, in accordance with some embodiments.

[00155] FIG. 5 is a schematic diagram illustrating performance improvements for anode channels comprising various multilayer designs, in accordance with some embodiments.

[00156] FIG. 6 is a schematic diagram illustrating a stack of fuel cells comprising a plurality of fuel cells, in accordance with some embodiments.

[00157] FIG. 7 is a schematic diagram illustrating durability testing results for a stack of fuel cells with a multi-layer gas diffusion layer design when nitrogen is present in a hydrogen gas mixture (3: 1 hydrogen and nitrogen volume ratio), in accordance with some embodiments.

[00158] FIG. 8 is a schematic diagram illustrating durability testing results for a stack of fuel cells with a multi-layer gas diffusion layer design with a hydrogen and nitrogen gas mixture stream produced from an ammonia reforming process, in accordance with some embodiments.

[00159] FIG. 9 is a schematic diagram illustrating a system for processing a source material comprising hydrogen and nitrogen, in accordance with some embodiments.

[00160] FIG. 10 is a schematic diagram illustrating a process for feeding reformate gas to a fuel cell, in accordance with some embodiments.

[00161] FIG. 11 is a schematic diagram illustrating various examples of cut configurations that may be utilized for an anode channel of a fuel cell, in accordance with some embodiments.

[00162] FIG. 12 is a schematic diagram illustrating various examples of cutout configurations that may be utilized for an anode channel of a fuel cell, in accordance with some embodiments.

[00163] FIG. 13 is a schematic diagram illustrating various examples of multi-layer anode channel designs, in accordance with some embodiments. [00164] FIG. 14 is a graph illustrating energy density of ammonia compared with other fuels, in accordance with some embodiments.

[00165] FIGS. 15A-15C are schematic diagrams illustrating gas diffusion layers (GDLs) for an anode of a fuel cell, in accordance with some embodiments.

[00166] FIGS. 16A-16B are schematic diagrams illustrating reduction of current density variability between fuel cell stacks, in accordance with some embodiments.

[00167] FIGS. 17A-17C are schematic diagrams illustrating cylindrical fuel cells, in accordance with some embodiments.

[00168] FIGS. 18A-21B are block diagrams illustrating an HC reforming system, in accordance with one or more embodiments of the present disclosure.

[00169] FIGS. 22A-22I are block diagrams illustrating utilization of a controller and sensors to control the HC reforming system shown in FIGS. 18A-21B, in accordance with one or more embodiments of the present disclosure.

[00170] FIGS. 23A-23T are block diagrams illustrating additional or alternative components and processes of the HC reforming system shown in FIGS. 18A-21B, in accordance with one or more embodiments of the present disclosure.

[00171] FIG. 24-28C are flow charts illustrating startup processes for an HC reforming method, in accordance with one or more embodiments of the present disclosure.

[00172] FIGS. 29A-29B are flow charts illustrating post-startup processes for an HC reforming method, in accordance with one or more embodiments of the present disclosure.

[00173] FIG. 30 is a schematic diagram illustrating utilization of an oxidation-resistant catalyst to generate reformate to purge the HC reforming system shown in FIGS. 18A-21B, in accordance with one or more embodiments of the present disclosure.

[00174] FIG. 31 is a schematic diagram illustrating a computer system that is programmed or otherwise configured to implement systems and/or methods of the present disclosure, in accordance with some embodiments.

DETAILED DESCRIPTION

[00175] While various embodiments of the invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous variations, changes, and substitutions may occur to those skilled in the art without departing from the invention. It should be understood that various alternatives to the embodiments of the invention described herein may be employed. It should be understood that any of the embodiments, configurations and/or components described with respect to a particular figure may be combined with other embodiments, configurations, and/or components described with respect to other figures.

[00176] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well (and vice versa), unless the context clearly indicates otherwise. For example, “a,” “an,” and “the” may be construed as “one or more.”

[00177] The present disclosure may be divided into sections using headings. The headings should not be construed to limit the present disclosure, and are merely present for organization and clarity purposes.

[00178] The expressions “at least one of A and B” and “at least one of A or B” may be construed to mean at least A, at least B, or at least A and B (i.e., a set comprising A and B, which set may include one or more additional elements). The term "A and/or B" may be construed to mean only A, only B, or both A and B.

[00179] The expressions “at least about A, B, and C” and “at least about A, B, or C” may be construed to mean at least about A, at least about B, or at least about C. The expressions “at most about A, B, and C” and “at most about A, B, or C” may be construed to mean at most about A, at most about B, or at most about C.

[00180] The expression “between about A and B, C and D, and E and F” may be construed to mean between about A and about B, between about C and about D, and between about E and about F. The expression “between about A and B, C and D, or E and F” may be construed to mean between about A and about B, between about C and about D, or between about E and about F.

[00181] The expression “about A to B and C to D” may be construed to mean between about A and about B and between about C and about D. The expression “about A to B or C to D” may be construed to mean between about A and about B or between about C and about D. [00182] The terms “decompose,” “dissociate,” “reform,” “crack,” and “break down,” and their grammatical variations, may be construed interchangeably. For example, the expression “decomposition of ammonia” may be interchangeable with “dissociation of ammonia,” “reforming of ammonia,” “cracking of ammonia,” etc.

[00183] The terms “ammonia conversion,” “ammonia conversion rate,” and “ammonia conversion efficiency,” and their grammatical variations, may be construed as a fraction of ammonia that is converted to hydrogen and nitrogen, and may be construed interchangeably. For example, “an ammonia conversion efficiency of 90%” may represent 90% of ammonia being converted to hydrogen and nitrogen. The term “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction (2NH3 — > N2 + 3H2; an endothermic reaction) is heated by a hydrogen combustion reaction (2H2 + O2 2H2O; an exothermic reaction) using at least part of the hydrogen produced by the ammonia decomposition reaction itself.

[00184] In some cases, the term “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction is heated by a hydrogen combustion reaction using at least part of hydrogen produced by the ammonia decomposition reaction itself, electrical heating, or a combination of both (which may result in an overall positive electrical and/or chemical energy output). For example, if “auto-thermal reforming” is performed using a hydrogen combustion reaction and/or electrical heating, the hydrogen produced from the ammonia decomposition reaction may be enough to provide the hydrogen combustion reaction with combustion fuel, and/or to provide electrical energy for the electrical heating via hydrogen-to- electricity conversion devices (e.g., fuel cell, combustion engine, etc.).

[00185] In some cases, the hydrogen provided for the hydrogen combustion reaction and/or the electrical heating may or may not use the hydrogen from the ammonia decomposition reaction (for example, the hydrogen may be provided by a separate hydrogen source, the electricity may be provided from batteries or a grid, etc.).

[00186] In some cases, “auto-thermal reforming” may be construed as a condition where an ammonia decomposition reaction is heated by a combustion reaction (e.g., ammonia combustion, hydrocarbon combustion, etc.), electrical heating, or a combination of both, which may result in an overall positive electrical and/or chemical energy output. For example, if “autothermal reforming” is performed using a combustion reaction and/or electrical heating, the chemical energy (e.g., lower heating value) from the hydrogen produced from the ammonia decomposition reaction may be higher than the combustion fuel chemical energy (e.g., lower heating value), and/or may be enough to provide electrical energy for the electrical heating via hydrogen-to-electricity conversion devices (e.g., fuel cell, combustion engine, etc.).

Fuel Cell

[00187] FIG. 1 schematically illustrates a system including a fuel cell 100 and an ammonia reforming module 112, in accordance with some embodiments.

[00188] The fuel cell 100 may comprise an electrochemical circuit including an anode 101, a cathode 103, and an electrolyte 102 between the anode and the cathode. The electrochemical circuit may comprise an electrical load 104 configured to receive electrical energy generated by the fuel cell 100. The fuel cell 100 may comprise a first channel 105 (“the anode channel”) comprising a first inlet 106 and a first outlet 107, wherein the first channel is in fluid communication with the anode 101. The anode channel 105 may include an anode gas diffusion layer (GDL). The fuel cell 100 may comprise a second channel 108 (“the cathode channel”) comprising a second inlet 109 and a second outlet 110, wherein the second channel is in fluid communication with the cathode 103. The cathode channel 108 may include a cathode GDL.

[00189] Hydrogen may be provided to the fuel cell 100 via a first inlet 106, such that the hydrogen contacts the anode 101. The hydrogen may diffuse to the anode catalyst and dissociate into protons and electrons via a first half reaction (H2 —> 2H ⁺ + 2e"). The protons (H ⁺ ) may be conducted through the electrolyte 102 to the cathode 103, while the electrons (e‘) may be conducted through an external circuit (connected to the electrical load 104) to the cathode 103.

[00190] A stream comprising oxidizing material 113 (e.g., oxygen) may be provided to the fuel cell 100 via a second inlet 109, such that the oxidizing material 113 contacts the cathode 103. The protons (H ⁺ ) and the electrons (e‘) may recombine at the cathode catalyst via a second half reaction (2H ⁺ + 2e" + V2O2 —> H2O). Oxygen may react with the protons and the electrons to form a byproduct (e.g., water).

[00191] As a whole, the fuel cell 100 may perform an electrochemical reaction comprising 2H2 + O2 2H2O. In one example, the standard potential of the electrochemical reaction is about 1.23 Volts. The output voltage of the fuel cell 100 may be lower than the standard potential, due to electrical potential losses during operation of the fuel cell 100 (e.g., due to kinetic losses, Ohmic losses, and/or mass transfer losses).

[00192] The hydrogen 111 may be processed by the one or more fuel cells 100 to generate energy (e.g., electrical energy). In some embodiments, the hydrogen may be provided by an ammonia reforming module 112 (e.g., a system for cracking or decomposing ammonia into hydrogen and nitrogen). The ammonia reforming module may comprise, for example, a storage tank 118 for storing fuel (e.g., ammonia, and optionally hydrogen) and a reactor 115 (i.e., reformer or cracker) for reacting ammonia to generate hydrogen and nitrogen (e.g., in a volume ratio of H2 to N2 of about 3: 1).

[00193] FIG. 2A is a plot illustrating the current-voltage characteristic when a fuel cell is processing high purity hydrogen (e.g., about 99.999% purity hydrogen by volume) versus a mixture of about 75% hydrogen and about 25% nitrogen. As shown in FIG. 2A, processing a mixture comprising hydrogen and nitrogen may reduce the electrical power output of a fuel cell, compared to processing high purity hydrogen (e.g., greater than about 99% purity). The fuel cell receiving the mixture of hydrogen and nitrogen showed significantly lower electrical power output (e.g., a drop from about 11 Watts to about 1 Watt at a current output of 20 Amps). [00194] FIG. 2B is a schematic diagram illustrating the diffusion of pure H2 versus an H2/N2 mixture in an anode GDL of a fuel cell. In cases where the anode GDL is used for diffusion and transport of mostly hydrogen, the hydrogen may flow from an inlet of the anode GDL to an outlet of the anode GDL. As the hydrogen flows through the anode GDL, it may also diffuse to the anode catalyst where the dissociation of hydrogen into protons and electrons occurs . Without being bound to a particular theory, in cases where the anode GDL is used for transport of a source material comprising both hydrogen and nitrogen (e.g., a hydrogen/nitrogen mixture), the transport of hydrogen to the proton-exchange membrane (PEM) may be restricted, in part due to the buildup or accumulation of nitrogen in the GDL (in other words, the nitrogen may dilute the hydrogen). This accumulation of nitrogen may lead to greater electrical potential losses (e.g., associated with mass transfer of the hydrogen) in the GDL. In some cases, this accumulation of nitrogen may lead to non-uniform dispersion of hydrogen through the GDL ( since some portions of the GDL may receive less hydrogen compared to other portions of the GDL). In some cases, this accumulation of nitrogen may lead to non-uniform dispersion of hydrogen to the anode (e.g., some portion of the anode may receive less hydrogen compared to other portions of the anode). In some cases, this accumulation of nitrogen can lead to insufficient hydrogen ion (proton) transport through the PEM. This nitrogen accumulation may result in reduced fuel cell performance and/or fuel cell starvation.

[00195] In some embodiments, an anode channel may comprise one or more features configured to improve processing a source material comprising hydrogen and nitrogen by the fuel cell. In some embodiments, the one or more features can comprise one or more cuts, one or more cutouts, and/or one or more grooves. The one or more features may be configured to continuously purge nitrogen out of the fuel cell. Reducing the nitrogen accumulation in at least part of the anode may increase a hydrogen consumption rate of the fuel cell, increase an output voltage of the fuel cell, or both. In some cases, reducing the nitrogen accumulation in at least a part of the fuel cell adjacent to the anode may increase a hydrogen consumption rate of the fuel cell, increase an output voltage of the fuel cell, or both. The one or more features may be configured to purge nitrogen from the fuel cell while the fuel cell is generating electricity. The anode channel comprising the one or more features may comprise a GDL comprising the one or more features.

[00196] FIG. 3 is a plot and a schematic diagram illustrating performance improvements for anode channels comprising one or more cuts. The one or more cuts may be positioned in the anode channels in various cut configurations (e.g., Cut 1, Cut 2, Cut 3, Cut 4). In instances where a mixture of hydrogen and nitrogen (e.g., about 3: 1 volume ratio) is provided to a fuel cell for processing to generate electrical energy, the output voltage of a fuel cell comprising one or more cuts in the anode channel may be significantly greater than the output voltage of a fuel cell without any cuts in the anode channels. In some cases, a fuel cell comprising a higher density of cuts on the surface of the anode channel may exhibit better performance (e.g., a higher output voltage when processing a hydrogen/nitrogen mixture to generate electrical energy) compared to a fuel cell with a lower density of cuts (or without cuts) on the surface of the anode channel. [00197] FIG. 4 is a plot and a schematic diagram illustrating performance improvements for anode channels comprising one or more cutouts. The one or more cutouts may be positioned in the anode channels in various cutout configurations (e.g., Cutout 1, Cutout 2, Cutout 3, Cutout 4). In instances where a mixture of hydrogen and nitrogen (about 3: 1 volume ratio) is provided to a fuel cell for processing to generate electrical energy, the output voltage of a fuel cell comprising one or more cutout in the anode channel may be significantly greater than the output voltage of a fuel cell without any cutouts in the anode channels. In some cases, a fuel cell comprising a higher density of cutouts on the surface of the anode channel may exhibit better performance (e.g., a higher output voltage when processing a hydrogen/nitrogen mixture to generate electrical energy) compared to a fuel cell with a lower density of cutouts (or without cutouts) on the surface of the anode channel. In some cases, a fuel cell comprising a density of cutouts on the surface of the anode channel that is too high may reduce the performance compared to a fuel cell with a lower density of cutouts on the surface of the anode channel. [00198] FIG. 5 is a plot and a schematic diagram illustrating performance improvements for anode channels comprising various multilayer anode channel designs (Design 1, Design 2, Design 3, Design 4). The multilayer anode channel designs can comprise a plurality of layers, where at least one of the layers comprises one or more cuts, cutouts, grooves, or any combination thereof. In instances where a mixture of hydrogen and nitrogen is provided to a fuel cell for processing to generate electrical energy, the output voltage of a fuel cell comprising a multilayer anode channel design may be significantly greater than the output voltage of a fuel cell without a multilayer anode channel design.

[00199] As shown in FIG. 3, FIG. 4, and FIG. 5, the one or more features of the anode channels may advantageously enable a fuel cell electrical power that is at least about 50% of a reference electrical power(e.g., generated using a fuel cell that receives a stream comprising at least about 99% hydrogen by moles). For instance, the design Cut 2 shown in FIG. 3 exhibits a voltage that is about 60% of the voltage of the reference electrical power at a current of about 20 Amps. Some designs exhibit a voltage that is nearly 100% of the voltage of the reference electrical power (e.g., Design 1 shown in FIG. 5). The electrical power and the reference electrical power of the fuel cell can be generated at a same current or a same hydrogen consumption rate. In some cases, the electrical power is at least about 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% of the reference electrical power. In some cases, the electrical power is at most about 60, 70, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% of the reference electrical power.

[00200] The one or more features can increase the hydrogen consumption rate of the fuel cell. The increase in the hydrogen consumption rate of the fuel cell may be in comparison to an equivalent fuel cell without the one or more features. In some cases, the one or more features increase the hydrogen consumption rate by at least about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. In some cases, the one or more features increase the hydrogen consumption rate by at most about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. In some cases, the hydrogen consumption rate can be at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen provided to the fuel cell. In some cases, the hydrogen consumption rate can be at most about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 99% of the hydrogen provided to the fuel cell.

[00201] In some cases, the hydrogen consumption rate of the fuel cell can be adjusted to maintain an autothermal reforming process of the ammonia reformer. An autothermal reforming process may be construed as a process in which the ammonia reforming process of the ammonia reformer generates a net positive production of hydrogen by combusting or consuming at least part of the hydrogen produced by the ammonia reformer. In some cases, an autothermal reforming process of the ammonia reformer is maintained by combusting at least part of hydrogen provided to the fuel cell that is not consumed by the fuel cell (e.g., unconverted hydrogen that passes from the anode inlet to the anode outlet). For example, the unconverted hydrogen may be directed to one or more combustion heaters of the ammonia reformer, and combusted in the one or more combustion heaters to heat the ammonia reformer. In some cases, an autothermal reforming process of the ammonia reformer is maintained by combusting at least part of hydrogen provided to the fuel cell that is not consumed by the fuel cell, and additionally by electrical heating (which may be provided by at least part of the electricity generated from the fuel cell). In some cases, an autothermal reforming process of the ammonia reformer is maintained by combusting at least part of the hydrogen produced by the ammonia reformer, and additionally by electrical heating.

[00202] The hydrogen consumption rate may be adjusted by modulating a load power of the fuel cell (e.g., the power required by a device in electrical communication with the fuel cell). In some cases, the hydrogen consumption rate of the fuel cell is about 20% to 40% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 30% to 50% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 40% to 60% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 50% to 70% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 60% to 80% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 70% to 90% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is about 55% to 75% of the hydrogen provided to the fuel cell to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is at least about 20, 30, 40, 50, 60, 70, 80, or 90% to maintain the autothermal reforming process of the ammonia reformer. In some cases, the hydrogen consumption rate is at most about 20, 30, 40, 50, 60, 70, 80, or 90% to maintain the autothermal reforming process of the ammonia reformer.

[00203] In some cases, the hydrogen consumption rate is maintained within a selected tolerance of a target hydrogen consumption rate to maintain the autothermal reforming process of the ammonia reformer. For example, for a target hydrogen consumption rate of about 50% with a selected tolerance of about 10%, the hydrogen consumption rate may be maintained in the range of from about 45% to 55%. In some cases, the selected tolerance of a target hydrogen consumption rate is at least about 1%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the target consumption rate. In some cases, the selected tolerance of a target hydrogen consumption rate is at most about 1%, 5%, 10%, 15%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of the target consumption rate. In some cases, the hydrogen consumption rate is adjusted at least in part based on the temperature of the ammonia reformer. In some cases, the hydrogen consumption rate is reduced when the temperature of the one or more combustion heaters of the ammonia reformer or the ammonia reformer starts to decrease, so that more hydrogen is provided to the one or more combustion heaters. In some cases, the hydrogen consumption rate is increased when the temperature of the one or more combustion heaters of the ammonia reformer or the ammonia reformer starts to increase, so that less hydrogen is provided to the one or more combustion heaters.

[00204] In some cases, the hydrogen consumption rate of the fuel cell is maintained within the selected tolerance of a target hydrogen consumption rate and one or more air flow rates comprising at least oxygen provided by one or more air supply units is adjusted to maintain the auto-thermal reforming process of the ammonia reformer. In some cases, the one or more air flow rates are reduced when the temperature of the one or more combustion heaters of the ammonia reformer, or the temperature of the ammonia reformer, starts to increase (so that less oxygen is provided to the one or more combustion heaters). In some cases, the one or more air flow rates are increased when the temperature of the one or more combustion heaters of the ammonia reformer or the ammonia reformer starts to decrease (so that more oxygen is provided to the one or more combustion heaters). In some cases, both the hydrogen consumption rate of the fuel cell and the one or more air flow rates are adjusted simultaneously based at least in part on the temperature of the one or more combustion heaters of the ammonia reformer and/or the temperature of the ammonia reformer.

[00205] The one or more features may increase the output voltage of the fuel cell. The increase in the output voltage of the fuel cell may be in comparison to an output voltage of an equivalent fuel cell without the one or more features. In some cases, the one or more features increase the output voltage by at least about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. In some cases, the one or more features increase the output voltage by at most about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%.

[00206] The one or more features may increase a power density of the fuel cell. The increase in the power density of the fuel cell may be in comparison to the power density of an equivalent fuel cell without the one or more features. In some cases, the one or more features may increase the power density by at least about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. In some cases, the one or more features may increase the power density by at most about 5, 10, 20, 40, 60, 80, 100, 120, 140, 160, 180, or 200%. The power density of the fuel cell may be at least about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kilowatt per liter (kW/L) (i.e., a ratio of an electrical power output to a volume of one or more fuel cells or one or more fuel cell stacks). The power density of the fuel cell may be at most about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, or 30 kW/L.

[00207] The one or more features may reduce a physical footprint (e.g., size/volume, weight, etc.) of a fuel cell. The reduced footprint may enable the fuel cell to be integrated into applications where a lighter weight and/or smaller volume are desirable (e.g., aerial vehicles), or into applications where the size is limited and power requirements are high (e.g., some industrial vehicles). In some embodiments, the fuel cell comprising the one or more features may be configured to provide a ratio of an electrical power output of the fuel cell to a projected surface area of the anode that is at least about 0.05 watt per square centimeter (W/cm ² ). In some embodiments, the ratio may be at least about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm ² . In some embodiments, the ratio may be at most about 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, or 0.4 W/cm ² . The ratio may be based on the anode channel receiving a first continuous stream comprising about 25% nitrogen and about 75% hydrogen by moles, and the cathode channel receiving a second continuous stream comprising at least about 20% oxygen by moles (e.g., air). In some cases, the ratio may be based on the first continuous stream comprising a hydrogen flow rate of at least about 0.001, 0.01, 0.1, 1, 10, 100, 1000, 10000, or 100000 mole per second. In some cases, the ratio may be based on the second continuous stream comprising an oxygen flow rate of at least about 0.0001, 0.001, 0.01, 0.1, 1, 10, 100, 1000, 10000, 100000, 1000000 mole per second. In some cases, the ratio may be based on the first continuous stream comprising hydrogen and nitrogen from the ammonia reformer. The projected surface area may be construed as the largest possible surface area of the anode projected onto a flat plane. The projected surface area may be a surface area of the largest surface of the anode. The largest surface may be defined at the largest flat surface of the anode.

[00208] FIG. 6 schematically illustrates a stack or module of fuel cells 601 comprising a plurality of fuel cells, in accordance with some embodiments. Each fuel cell of the plurality of fuel cells may comprise one or more cathode channels 602 (e.g., for flowing air), a cathode current collecting layer, a cathode gas diffusion layer (GDL) 603, an anode GDL 605, an anode current collecting layer 606, and an electrolyte 604 disposed between the cathode GDL 603 and the anode GDL 605. The plurality of fuel cells can be adjacently coupled with one another. [00209] The fuel cell design may be adapted for use in one or more fuel cell stacks or modules 601 comprising one or more fuel cells. A fuel cell module may comprise a stack of fuel cells or multiple stacks of fuel cells. The fuel cells may be arranged in a lateral configuration or a circular configuration. The fuel cells in the fuel cell stack may be arranged on top of each other and/or next to each other. Each of the fuel cells may comprise one or more inlets for receiving hydrogen. The fuel cell stack or the one or more fuel cells of the fuel cell stack may be in fluid communication with the ammonia reformer or reactor in order to receive hydrogen to generate electricity. The fuel cells may be electrically coupled in series or in parallel. In some cases, the one or more fuel cell stacks or modules may be in series or in parallel fluid communication with each other. The fuel cells may be configured to process the source material to generate electrical energy. The fuel cells stack or module (e.g., 601) can comprise any number of fuel cells. For instance, the fuel cells can comprise at least about 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10,000 fuel cells. The fuel cells can comprise at most about 2, 3, 4, 5, 6, 7, 8, 9, 10, 100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10,000 fuel cells.

[00210] FIG. 7 schematically illustrates durability testing results for a stack of fuel cells with a multi-layer gas diffusion layer design provided with a mixture of hydrogen and nitrogen, in accordance with some embodiments. The durability testing was conducted using a fuel cell stack comprising 32 fuel cells and a gas diffusion layer comprising a double layer design. A gaseous mixture of hydrogen and nitrogen (comprising a hydrogen to nitrogen volume ratio of about 3: 1) was provided to the fuel cell stack for a one-hour endurance test. The gaseous hydrogen was provided at a volumetric flow rate of about 15 standard liters per minute and the gaseous nitrogen was provided at a volumetric flow rate of about 5 standard liters per minute. As shown in the plot in FIG. 7, the power output of the fuel cell stack stabilized at about 572 Watts.

[00211] FIG. 8 schematically illustrates durability testing results for a stack of fuel cells with a multi-layer gas diffusion layer design provided with a mixture of hydrogen and nitrogen produced from an ammonia reforming process (about 3 : 1 hydrogen to nitrogen volume ratio), in accordance with some embodiments. A stack of five fuel cells was tested using the gas mixture produced during an ammonia reforming process. No appreciable differences in fuel cell performance were observed between a first test scenario involving the processing of reformate gases produced during ammonia reforming, and a second test scenario involving the processing of a mixture of hydrogen and nitrogen from a gas tank. Further, no major degradations in fuel cell performance were observed over the operational time period.

[00212] The fuel cells in a stack can be electrically coupled. The fuel cells can be electrically coupled in series to provide higher voltage. In some cases, a fuel cell can provide at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2 volt (V) in output voltage. In some cases, a fuel cell can provide at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, or 1.2 in output voltage. Fuel cells electrically coupled in series can provide a total output voltage that is equal to about the sum of the output voltage of each of the fuel cells coupled in series. For instance, a plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 V. A plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilovolt (kV). A plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 megavolt (MV). A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 V. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kV. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 MV.

[00213] The fuel cells can be electrically coupled in parallel to provide a higher current. A fuel cell can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 ampere (A). A fuel cell can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 A. Fuel cells electrically coupled in parallel can provide a total output current that is equal to the sum of the output current of each of the fuel cells coupled in parallel. For instance, a plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 A. A plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kA. A plurality of fuel cells can provide at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 MA. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 A. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kA. A plurality of fuel cells can provide at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 MA.

[00214] One or more ammonia reformers can be configured to provide a plurality of streams comprising hydrogen and nitrogen to the plurality of the fuel cells. In some embodiments, the one or more ammonia reformers comprise one ammonia reformer. In some embodiments, the one or more ammonia reformers comprise at least about 2, 3, 4, 5, 6, 7, 8, 9, or 10 ammonia reformers.

[00215] In some embodiments, at least one fuel cell of the plurality of fuel cells outputs a different electrical power than other fuel cells of the plurality of fuel cells. In some cases, at least one fuel cell of the plurality of fuel cells is configured to reduce an electrical power output while others of the plurality of fuel cells maintain their respective power outputs. For example, one or more fuel cells of the plurality of fuel cells can operationally or intermittently reduce power output to about 0% to 50% of a first power level, while the other fuel cells of the plurality of fuel cells output about 50% to 100% of the first power level. In some cases, at least one fuel

- l- cell of the plurality of fuel cells is configured increase an electrical power output while others of the plurality of fuel cells maintain their electrical power outputs.

[00216] In some cases, a system comprising the plurality of fuel cells can be configured to detect a fault in at least one fuel cell of the plurality of fuel cells. The fault can be detected via, for example, a temperature sensor, a voltage sensor, a current sensor, a pressure sensor, a flow sensor, etc., that is operatively coupled to the at least one fuel cell and a controller. In some cases, after detecting a fault, at least one fuel cell of the plurality of fuel cells is configured to shut down or reduce power generation based on the fault, and/or an inlet flow of the at least one fuel cell is configured to be reduced or shut down based on the fault, while the other fuel cells of the plurality of fuel cells may continue to output electrical power. The controller may operate the at least one fuel cell to reduce or shut down the inlet flow. In some cases, the fault may comprise a temperature of the inlet flow being greater than a threshold temperature, an ammonia concentration being greater than a threshold ammonia concentration, a pressure of the inlet flow being greater than a threshold pressure, a decrease in voltage below a threshold voltage, an inlet flow rate less than or greater than a threshold flow rate, etc. In some cases, after the fault is at least partly resolved, the controller can operate the at least one fuel cell to increase the inlet flow or power generation. In some cases, the fault is at least partly resolved when at least one of: a temperature of the inlet flow returns to a target temperature range, an ammonia concentration returns to less than a threshold concentration, a pressure of the inlet flow returns to a target pressure range, voltage level returns to a target voltage range, or an inlet flow returns to a target flow rate range.

[00217] In some embodiments, the plurality of fuel cells comprises at least one fuel cell that is different in size, power output, hydrogen consumption rate, power density, or operating temperature from others of the plurality of fuel cells. In some embodiments, the plurality of fuel cell stacks or modules comprises at least one fuel cell stack or module that is different in size, power output, hydrogen consumption rate, power density, or operating temperature from others of the plurality of fuel cell stacks or modules.

[00218] In some embodiments, at least one fuel cell of the plurality of the fuel cells is in serial fluid communication with at least one other fuel cell of the plurality of the fuel cells. For example, exit flows of one or more fuel cells of the plurality of fuel cells can provide the inlet flows of one or more other fuel cells of the plurality of fuel cells. In some cases, at least one fuel cell of the plurality of the fuel cells is different in size, power output, hydrogen consumption rate, power density, or operating temperature from at least one other fuel cell of the plurality of the fuel cells that are in serial fluid communication. [00219] In some embodiments, at least one fuel cell of the plurality of the fuel cells is in parallel fluid communication to at least one other fuel cell of the plurality of the fuel cells. In some cases, at least one fuel cell of the plurality of the fuel cells is different in size, power output, hydrogen consumption rate, power density, or operating temperature from at least one other fuel cell of the plurality of the fuel cells that are in parallel fluid communication.

[00220] In some embodiments, at least one fuel cell stack or module of the plurality of fuel cell stacks or modules is in serial fluid communication to at least one other fuel cell stack or module of the plurality of fuel cell stacks or modules. For example, exit flows of one or more fuel cell stacks or modules of the plurality of fuel cell stacks or modules can provide the inlet flows of one or more other fuel cell stacks or modules of the plurality of fuel cell stacks or modules. In some cases, at least one fuel cell stack or module of the plurality of the fuel cell stacks or modules is different in size, power output, hydrogen consumption rate, power density, or operating temperature from at least one other fuel cell stack or module of the plurality of the fuel cell stacks or modules that are in serial fluid communication. For example, a first fuel cell stack that outputs an exit flow to an inlet flow of a second fuel cell stack may be in larger in size or may output a higher power.

[00221] In some embodiments, at least one fuel cell stack or module of the plurality of fuel cell stacks or modules is in parallel fluid communication to at least one other fuel cell stack or module of the plurality of the fuel cell stacks or modules. In some cases, a flow comprising the source material may be distributed between two or more fuel cell stacks or modules of the plurality of fuel cell stacks or modules within at least about 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of a target flow rate (e.g., target inlet flow rate of a single fuel cell stack). In some cases, a flow comprising the source material may be distributed between two or more fuel cell stacks or modules of the plurality of fuel cell stacks or modules within at most about 1%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, or 100% of a target flow rate. In some cases, a flow comprising the source material may be distributed between two or more fuel cell stacks or modules of the plurality of fuel cell stacks or modules by a distribution factor. For example, when the distribution factor is about 4 to 5, a first fuel cell stack may receive a flow comprising the source material that is about 4 to 5 times higher (e.g., by weight, volume, moles, or concentration of the source material) than a second fuel cell stack. In some cases, the distribution factor may be at least about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some cases, the distribution factor may be at most about 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. In some cases, at least one fuel cell stack or module is different in size, power output, hydrogen consumption rate, power density, or operating temperature from at least one other fuel cell stack or module of the plurality of the fuel cell stacks or modules that are in parallel fluid communication.

[00222] In some cases, the fuel cell may be operated to intermittently reduce the hydrogen consumption rate (thus increasing the flow rate of unconverted hydrogen exiting the fuel cell) to purge out at least one of hydrogen, nitrogen, or water. The hydrogen consumption rate can be reduced by directing at least a part of a first continuous stream of hydrogen and nitrogen to the ammonia reformer. In some cases, the first continuous stream can be in direct fluidic communication with the one or more combustion heaters of the ammonia reformer. In some cases, at least the part of the first continuous stream can be flared at one or more combustion exhausts of one or more combustion heaters. In some cases, at least the part of the first continuous stream comprising hydrogen is vented out of one or more combustion exhausts of the one or more combustion heaters.

[00223] The one or more combustion heaters can be in thermal communication with the ammonia reformer for heating the ammonia reformer. The one or more combustion heaters can be in fluidic communication with the fuel cell to receive the at least the part of the first continuous stream.

[00224] The one or more features can be configured to facilitate purging of a select material from the anode gas diffusion layer. The select material can comprise one or more of nitrogen, ammonia, water, or one or more impurities. In some cases, the fuel cell can comprise one or more exit ports for discharging the select material and unconverted hydrogen from the fuel cell. In some cases, unconverted hydrogen from the plurality of fuel cells can be directed to the combustion heater of the at least one ammonia reformer or reactor for combustion heating. One or more air supply units can provide at least oxygen to the combustion heater of the ammonia reformer for combustion of the unconverted hydrogen. In some cases, unconverted oxygen from the plurality of fuel cells (e.g., one or more cathode exit flows) can provide at least oxygen to the combustion heater of the ammonia reformer for combustion of the unconverted hydrogen. In some cases, water may be removed from the stream comprising the unconverted hydrogen prior to combusting the unconverted hydrogen. In some cases, the stream comprising the unconverted hydrogen can be flared. The systems and the methods disclosed herein may be implemented using one or more fuel cells. The one or more fuel cells may be arranged in a fuel cell stack as disclosed elsewhere herein. In some non-limiting embodiments, the one or more fuel cells may comprise an anode, a cathode, and an electrolyte disposed between the anode and the cathode. In some cases, the anode may comprise a gas diffusion layer for directing hydrogen to facilitate processing of the hydrogen to generate an electrical current. In some cases, the gas diffusion layer may comprise one or more surface features configured to enhance a diffusion of hydrogen, for example, in a gaseous mixture of hydrogen and nitrogen.

[00225] In some embodiments, the one or more fuel cells may be in fluid communication with one or more reactor modules for catalytically decomposing ammonia. The one or more fuel cells may be configured to receive hydrogen and/or nitrogen produced or extracted using the one or more reactor modules, and to process the hydrogen/nitrogen mixture to generate electrical energy.

[00226] In some cases, the fuel cells may be in fluid communication with one or more reactors. The one or more reactors may be configured to catalytically decompose ammonia to generate hydrogen. The exit flow from the one or more reactors may comprise hydrogen, nitrogen, and/or unconverted ammonia. The exit flow from the one or more reactors may be directed to the one or more fuel cells, which may be configured to use (i.e., process) the exit flow or any portion thereof to generate electrical energy.

[00227] In an aspect, the present disclosure provides a method for processing hydrogen. The method may comprise providing a reactor exit flow comprising hydrogen and/or nitrogen to one or more fuel cells. The reactor exit flow may be from a reactor or a reformer for catalytically decomposing ammonia. In some cases, the reactor exit flow may be from various components or subcomponents of a reformer for catalytically decomposing ammonia. The various components or subcomponents may comprise, for example, a reactor, an adsorbent tower, or a heat exchanger of the reformer. The method may further comprise using the one or more fuel cells to process the reactor exit flow to generate electricity (i.e., an electrical current). [00228] In some cases, the exit flow from the one or more reactors may be directed to one or more adsorbents to remove excess or trace ammonia before the reactor exit flow is directed to the one or more fuel cells. The adsorbents may help to preserve performance and/or longevity of the one or more fuel cells since ammonia can be detrimental to the fuel cells. The adsorbents may be replaceable (e.g., as cartridges) after a certain number of cycles or operations. In some embodiments, a concentration of ammonia in the exit flow from the one or more adsorbents may be further reduced (before supplying the exit flow from the one or more adsorbents to the one or more fuel cells) using an additional ammonia filtration system in series fluidic communication with the one or more adsorbents. The additional ammonia filtration system may be an adsorbent-based, membrane-based, absorbent-based, a solvent-based, a water-based, or an acidic-based ammonia filtration system. In some cases, the additional ammonia filtration system comprises one or more ammonia filtration cartridges, so that when one or more cartridges are fully or at least partially spent (i.e., fully saturated with ammonia), the one or more fully or at least partially spent cartridges can be replaced with one or more new ammonia filtration cartridges.

[00229] In some cases, the fuel cells may be in fluid communication with a plurality of adsorption towers. The plurality of adsorption towers may comprise at least a first adsorption tower and a second adsorption tower. The first and/or second adsorption tower may be used to remove any traces of ammonia from the reactor exit flow before the reactor exit flow is directed to the one or more fuel cells. While the first adsorption tower is being used, the second adsorption tower may be regenerated (e.g., such that ammonia is desorbed from the second adsorption tower). Once the first adsorption tower is fully saturated (e.g., when the first adsorption tower is not able to adsorb additional ammonia), the second adsorption tower may be partially or fully regenerated and ready for use in another cycle or operation. In any of the embodiments described herein, two, three, four, five, six, seven, eight, nine, ten, or more adsorption towers may be used to filter the reactor exit flow before the reactor exit flow reaches the one or more fuel cells.

Proton-Exchange Membrane Fuel Cells

[00230] The fuel cells disclosed herein may comprise various types of fuel cells. In some cases, the electrolyte can comprise a membrane. In some cases, the membrane can comprise a proton-exchange membrane. In some cases, the fuel cells may comprise one or more protonexchange membrane fuel cells (PEMFCs) having a proton-conducting polymer electrolyte membrane. A proton exchange membrane fuel cell can be used to transform chemical energy into electrical energy by electrochemically reacting hydrogen and oxygen. In some cases, the PEMFC may comprise a proton-conducting polymer membrane that separates the anode and cathode sides of the PEMFC. In some cases, the fuel cells may comprise one or more PEMFCs, one or more solid oxide fuel cells (SOFCs), one or more molten carbonate fuel cells (MCFCs), one or more alkaline fuel cells (AFCs), one or more alkaline membrane fuel cells (AMFCs), or one or more phosphoric acid fuel cells (PAFCs).

[00231] The fuel cells of the present disclosure may comprise one or more PEMFCs that are adapted for use with a mixture of hydrogen and/or nitrogen. In some cases, the fuel cells of the present disclosure may be used to generate electrical energy from hydrogen gas mixtures containing impurities that would otherwise degrade the performance of conventional fuel cells (some of which may require up to about 99.7% pure hydrogen as a source material). The fuel cells of the present disclosure may provide better performance compared to fuel cells with a dead-end type design (e.g., a fuel cell without an outlet at the anode channel configured to direct unconverted hydrogen and/or nitrogen out of the fuel cell). The dead-end type design does not allow efficient processing of H2/N2 mixtures since N2 concentrations may build up without appropriate purging.

[00232] The fuel cells of the present disclosure may provide better performance compared to fuel cells with an intermittent purging operation that does not allow efficient processing of H2/N2 mixtures (since N2 concentrations may build up without continuous purging). In some cases, the continuous purging may be defined based on purging time ratio (a ratio of total purging time to total operational time while electricity is being generated by the one or more fuel cells). In some cases, one or more fuel cells are continuously purged when the purging time ratio is at least about 0.5 (i.e., purging of N2 occurs during at least about 50% of the total operational time). In some cases, one or more fuel cells are continuously purged when the purging time ratio is at least about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, the purging time ratio is about 1 (i.e., the purging of N2 occurs during about 100% of the total operational time).

[00233] The fuel cells disclosed herein may also provide enhanced performance compared to fuel cells with a flow-through design (e.g., a fuel cell with an outlet at the anode channel configured to direct unconverted hydrogen and/or nitrogen out of the fuel cell) that allows H2/N2 mixtures, since the fuel cells in such flow-through designs can experience fuel starvation if excess H2/N2 mixture is not provided or H2 from H2/N2 mixture is not distributed well in the anode. The presently disclosed fuel cells may be configured to utilize and process a H2/N2 mixture without experiencing similar degradations in performance that can be attributed to a buildup of N2 concentrations. Such advantages may be realized using, for example, optimally configured anode channels for the fuel cells (e.g., such as anode channels including cuts, cutouts, or grooves).

Source Material

[00234] In an aspect, the present disclosure provides a fuel cell design that can be compatible with various gas mixtures containing hydrogen, nitrogen, ammonia, and/or other reformate gases. Such gas mixtures may be provided by an ammonia reformer or a reactor configured to process (i.e., catalytically decompose) ammonia. Although hydrogen has a relatively high gravimetric density (measured in MJ/kg), fuel storage systems for compressed and liquefied hydrogen are often complex due to the need to provide and maintain specialized storage conditions. For example, storage of hydrogen as a gas may require high-pressure tanks (e.g., 350-700 bar or 5,000-10,000 pond per square inch (psi)). Storage of hydrogen as a liquid may require cryogenic temperatures because the boiling point of hydrogen at a pressure of 1 atm is -252.8° C. Using ammonia as a hydrogen carrier may provide several benefits over storing and transporting pure hydrogen, including easy storage at relatively standard conditions (0.8 megapascal (MPa), 20 °C in liquid form), and convenient transportation. Ammonia also has a relatively high hydrogen content (17.7 wt % or 120 grams of H2 per liter of liquid ammonia). Further, the production of ammonia using the Haber-Bosch process can be powered by renewable energy sources (e.g., solar photovoltaic, solar-thermal, wind turbines, geothermal, and/or hydroelectricity), which makes the production process environmentally safe and friendly, as N2 is the only byproduct and there is no further emission of CO2. Once the ammonia is produced, the ammonia may be processed to release the hydrogen through a dehydrogenation process (i.e., by dissociating, decomposing, reforming, or cracking the ammonia).

[00235] A source material can comprise various concentrations of hydrogen, nitrogen, and ammonia. When the source material is provided directly from an ammonia reformer, the ratio of nitrogen to hydrogen can be about 1 part nitrogen to 3 parts hydrogen by moles. There can be some ammonia in the source material, depending on the extent of conversion of the ammonia by the reformer. In some cases, the source material can be mixed with another gas before being provided to the one or more fuel cells. For instance, the source material can be mixed with a stream of high purity hydrogen gas (e.g., greater than about 99% purity). The source material can be mixed with a stream of high purity nitrogen gas (e.g., greater than about 99% purity). The source material can be purified before being provided to the one or more fuel cells. For instance, the source material can be contacted with an adsorbent or an absorbent to reduce ammonia concentration in the source material. In some cases, the source material can be provided by mixing high purity nitrogen and high purity hydrogen streams. Therefore, the concentrations and the amounts of hydrogen, nitrogen, and ammonia that is supplied to the one or more fuel cells can be varied.

[00236] FIG. 14 schematically illustrates ammonia as an energy carrier and various density characteristics of ammonia in comparison to other types of fuel. The H2 storage capacity of NH ₃ is about 17.7 wt % and 120 grams of H2 per liter of ammonia. Compared to other fuel types such as hydrogen, ammonia exhibits a favorable volumetric density in view of its gravimetric density. Further, in comparison to other types of fuel (including carbon-based fuels such as methane, propane, methanol, ethanol, gasoline, E-10 gasoline, JP-8 jet fuel, or diesel), the use of ammonia as a fuel may not produce harmful emissions such as CO2, CO, or black carbon (soot), and may produce zero or negligible NO _X (e.g., NO2 or N2O) emissions (especially in combination with a selective catalytic reduction [SCR] catalyst). Thus, the use of ammonia as an energy carrier allows some embodiments of the presently disclosed systems and methods to leverage the benefits of hydrogen fuel (e.g., environmentally safe and high gravimetric energy density) once the ammonia is decomposed into hydrogen, while taking advantage of (a) ammonia’s greater volumetric density compared to hydrogen and (b) the ability to transport ammonia at standard temperatures and pressures without requiring the complex and highly pressurized storage vessels typically used for storing and transporting hydrogen.

[00237] In some embodiments, the source material comprises a volume fraction of H2 of about 30% to about 99.7%. In some embodiments, the source material comprises a volume fraction of H2 of from about 30% to about 99.99%. In some embodiments, the source material comprises a volume fraction of H2 of from about 70% to about 99.999%. In some embodiments, the source material comprises a volume fraction H2 of from about 70% to about 80% when provided by ammonia reforming. In some embodiments, one or more hydrogen separation systems (e.g., pressure swing adsorption (PSA) or membrane separation) can be used to increase the volume fraction of hydrogen in the source material.

[00238] In some embodiments, the source material comprises a volume fraction of H2 of about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of H2 of at least about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of H2 of at most about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of H2 of about 30% to about 99.7%, about 35% to about 95%, about 40% to about 90%, about 45% to about 85%, about 50% to about 80%, about 55% to about 75%, about 60% to about 70%, about 65% to about 95%. [00239] In some embodiments, the source material comprises a molar fraction of H2 of at least about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween. In some embodiments, the source material comprises a molar fraction of H2 of at most about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween.

[00240] In some embodiments, the source material comprises a partial pressure fraction of H2 of at least about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween. In some embodiments, the source material comprises a partial pressure fraction of H2 of at most about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99.7%, or any value therebetween.

[00241] The source material can comprise various concentrations of nitrogen. In some cases, the source material comprises comprise a volume fraction of nitrogen of at least about 10%. In some cases, the source material comprises a volume fraction of nitrogen of at least about 20%. In some cases, the source material comprises a volume fraction of nitrogen ranging from about 20% to about 30%. In some cases, the source material comprises a volume fraction of nitrogen ranging from about 30% to about 50%. In some cases, the source material comprises a volume fraction of nitrogen ranging from about 40% to about 70%. In some embodiments, the source material comprises a volume fraction of nitrogen of about 10 %, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of nitrogen of at least about 10 %, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of nitrogen of at most about 10 %, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, or any value therebetween. In some embodiments, the source material comprises a volume fraction of nitrogen of about 10% to about 70%, about 15% to about 65%, about 20% to about 60%, about 25% to about 55%, about 30% to about 50%, about 35% to about 45%, about 40% to about 70%, or any value therebetween.

[00242] In some embodiments, the source material comprises a partial pressure fraction of N2 of at least about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99%, or any value therebetween. In some embodiments, the source material comprises a partial pressure fraction of N2 of at most about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99%, or any value therebetween.

[00243] In some embodiments, the source material comprises a molar fraction of N2 of at least about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99%, or any value therebetween. In some embodiments, the source material comprises a molar fraction of N2 of at most about 1%, about 5%, about 10%, about 15%, about 20%, about 25%, about 30 %, about 35%, about 40%, about 45%, about 50%, about 55%, about 60 %, about 65%, about 70%, about 75%, about 80%, about 85%, about 90%, about 95%, about 99%, or any value therebetween.

[00244] The source material can comprise various concentrations of ammonia. In some embodiments, the source material comprises an ammonia concentration that is less than about 0.1 ppm, about 0.2 ppm, about 0.3 ppm, about 0.4 ppm, about 0.5 ppm, about 0.6 ppm, about 0.7 ppm, about 0.8 ppm, about 0.9 ppm, about 1 ppm, about 1.2 ppm, about 1.4 ppm, about 1.6 ppm, about 1.8 ppm, about 2 ppm, or any value therebetween. In some embodiments, the source material comprises an ammonia concentration that is at most about 0.1 ppm, about 0.2 ppm, about 0.3 ppm, about 0.4 ppm, about 0.5 ppm, about 0.6 ppm, about 0.7 ppm, about 0.8 ppm, about 0.9 ppm, about 1 ppm, about 1.2 ppm, about 1.4 ppm, about 1.6 ppm, about 1.8 ppm, about 2 ppm, or any value therebetween. In some embodiments, the source material comprises an ammonia concentration that is between about 0.1 ppm and about 2 ppm, between about 0.2 ppm and about 1.8 ppm, between about 0.3 ppm and about 1.6 ppm, between about 0.4 ppm and about 1.4 ppm, between about 0.5 ppm and about 1.2 ppm, between about 0.6 ppm and about 1 ppm, between about 0.7 ppm and about 0.9 ppm, or between about 0.8 ppm and about 2 ppm. In some embodiments, an ammonia concentration in the first continuous stream is at most about 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm. In some embodiments, an ammonia concentration in the first continuous stream is at least about 1000, 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, 9, 8, 7, 6, 5, 4, 3, 2, or 1 ppm.

[00245] The source material can be provided to one or more fuel cells at various pressures. The source material can be provided to one or more fuel cells at an absolute pressure of at least about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or 40 bar. The source material can be provided to one or more fuel cells at an absolute pressure of at most about 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, or 40 bar. The source material can be provided to one or more fuel cells at an absolute pressure of about 1 to 5 bar. The pressure of the source material can be maintained within a selected tolerance while the source material is being provided to the one or more fuel cells. The selected tolerance can be about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 150, 200, 300, 400, 500, or 1000 percent of the absolute pressure. The pressure or the flow rate of the source material can be modulated while the source material is being provided to the one or more fuel cells. One or more flow regulators, pressure regulators, control units, or any combination thereof can be used to modulate the pressure or the flow rate. For example, one or more pressure regulators can reduce the pressure of the source material provided to the one or more fuel cells from an absolute pressure of about 5 to 10 bar to about 1.5 to 3 bar. The one or more flow regulators, pressure regulators, control units, or any combination thereof can be positioned upstream or downstream of the fuel cell. The one or more flow regulators, pressure regulators, control units, or any combination thereof can be positioned downstream of the fuel cell to prevent or reduce a back flow of the unconverted hydrogen or any other flows.

[00246] In some cases, the source material can be provided to a plurality of fuel cells, fuel cell stacks, or fuel cell modules as a plurality of streams. The flow rates or the pressures of the plurality of streams can be maintained or modulated. One or more flow regulators, pressure regulators, control units, or any combination thereof can be used to modulate the pressures or the flow rates. In some cases, at least one fuel cell of the plurality of the fuel cells can receive a stream at a flow rate that is different from the flow rates of other streams of the plurality of streams. In some cases, each of the plurality of the fuel cells can receive one of the plurality of streams at a flow rate that is about the same as or within a selected tolerance of other flow rates of others of the plurality of streams. In some cases, the selected tolerance is about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%. In some cases, the selected tolerance is at most about 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%.

Reformer

[00247] FIG. 9 schematically illustrates a block diagram of an example of a system for processing a source material 910 to produce electrical energy. The source material 910 may comprise hydrogen. In some cases, the source material 910 may further comprise one or more other gases, such as, for example, oxygen (O2), nitrogen (N2) and/or ammonia (NH3). The source material 910 may comprise one or more reformate gases that are generated by an ammonia processing system. The system can be configured to crack or decompose a hydrogen carrier (e.g., ammonia, a liquid organic hydrogen carrier (LOHC), formic acid (HCOOH), or methanol (CH3OH)) to extract or produce hydrogen. In some cases, the source material 910 may comprise various impurities, such as unconverted ammonia that has passed through the ammonia processing system, nitrogen that has mixed with the hydrogen extracted using the ammonia processing system, and/or other trace materials within the ammonia processing system.

[00248] The source material 910 may be provided to a fuel cell 920. The fuel cell 920 may be designed or configured to process the hydrogen to produce electrical energy 930. The electrical energy 930 may be used to power various system, vehicles, and/or devices, including, for example, terrestrial, aerial, aquatic, marine, submarine, or amphibious vehicles, mobile or stationary electric devices, or a stationary electrical grid. In some cases, the electrical energy 930 may be used as back-up power for the various systems, vehicles, and/or devices.

[00249] As described above, the one or more fuel cells 920 may be used to generate electrical energy 930 (e.g., an electrical current or a flow of electrons) using the source material 910, which may comprise hydrogen and/or nitrogen. In some cases, the one or more fuel cells may generate the electrical energy 930 through an electrochemical reaction of a fuel. The fuel may comprise the hydrogen in the source material 910. The electricity generated by the fuel cells may be used to power one or more systems, vehicles, or devices. In some embodiments, excess electricity generated by the fuel cells may be stored in one or more energy storage units (e.g., batteries) for future use. In some embodiments, the fuel cells may be provided as part of a larger fuel cell system.

[00250] In some non-limiting examples, the fuel cell system may comprise an electrolysis module. Electrolysis of a byproduct of the one or more fuel cells (e.g., water) may allow the byproduct to be removed through decomposition of the byproduct into one or more constituent elements (e.g., oxygen and/or hydrogen). Electrolysis of the byproduct can also generate additional fuel (e.g., hydrogen) for the fuel cell. The energy required to run the electrolysis module can, in part, come from excess electricity sources including, but not limited to, solar power, wind power, hydro power, nuclear power, combustion engines, combustion turbines, steam turbines, etc. In some cases, the fuel cell may receive the source material from one or more reformers. The one or more reformers may be configured to perform a catalytic decomposition or cracking of ammonia to extract and/or produce hydrogen. The exit flow from the reformers may comprise the extracted hydrogen and/or other gases (e.g., nitrogen and/or ammonia). The exit flow may correspond to the source material usable by the fuel cells to generate electrical energy. In some cases, the reformers may be operated using heat energy. In some cases, the reformers may be heated using a combustor that generates heat energy to drive the operation of the reformers. In some cases, the heat energy may be generated from the combustion of a chemical compound (e.g., hydrogen or a hydrocarbon). The hydrogen that is generated and/or extracted using the reformers may be provided to the one or more fuel cells, which may produce electrical energy to power one or more systems, sub-systems, or devices requiring electrical energy to operate. In some cases, the hydrogen generated and/or extracted using the reformers may be provided to one or more other reactors or reformers. In such cases, the one or more other reactors or reformers may be configured to combust the hydrogen to generate thermal energy. Such thermal energy may be used to heat the one or more other reactors or reformers to facilitate a further catalytic decomposition or cracking of ammonia to extract and/or produce additional hydrogen. In some cases, the reformers or reactors may be heated using electrical heating, resistive heating, or Joule heating. In some cases, the reformers or reactors may be heated using the combustion heating and electrical heating, resistive heating, or Joule heating. In such cases, a current may be passed through an electrical heater, a catalyst, or a catalyst bed of the reformer to heat the catalyst directly.

[00251] FIG. 10 schematically illustrates a process for feeding reformate gas to a fuel cell, in accordance with some embodiments. The reformate gas may comprise a mixture of hydrogen and nitrogen. The mixture may comprise a ratio of hydrogen gas to nitrogen gas by weight or volume. The ratio may be, for example, X:Y, where X corresponds to hydrogen (e.g., 3 for ammonia reforming) and Y corresponds to nitrogen (e.g., 1 for ammonia reforming) in volume, mole, or partial pressure basis ratio, and where X and Y are any integer greater than or equal to 1. The reformate gases may comprise one or more gases constituting the exit flow from a reformer (or any components or subcomponents thereof). The reformer may comprise an ammonia reformer for catalytically decomposing ammonia. The catalytic decomposition of ammonia may be driven using a heat source. The heat source may comprise one or more combustors and/or one or more electrical heaters. The one or more combustors may be configured to combust hydrogen, ammonia, one or more hydrocarbons, or any combination thereof to generate thermal energy. The one or more electrical heaters may be configured to covert electrical energy to thermal energy via joule heating mechanism. The thermal energy may be used to drive the catalytic decomposition of ammonia.

Channel Features

[00252] The one or more features can comprise various dimensions, shapes, and orientations. In some cases, the one or more features can comprise one or more cuts, one or more cutouts, one or more grooves, or any combination thereof. In some cases, a cut can be an incision or slit in an anode channel. In some cases, a cut may comprise removal of a substantially minor amount of material (e.g., zero material or close to zero material by weight, for example, less than about 1 to 3% by weight) from the anode channel. A cutout can be an opening in an anode channel. A cutout can comprise removal of a substantial amount of material from the anode channel. A groove can be a recess or trench in the anode channel comprising a depth that does not extend through the entire thickness of the anode channel. A groove can comprise removal of a substantial amount of material from the anode channel. A groove can comprise removal of a substantially minor amount of material from the anode channel.

[00253] The one or more features can comprise various depths. The one or more features can comprise a depth less than about 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 millimeter (mm). The one or more features can comprise a depth greater than about 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, 0.1, 0.09, 0.08, 0.07, 0.06, 0.05, 0.04, 0.03, 0.02, or 0.01 mm. The depth of the one or more features may be construed with respect to a thickness of the GDL. In some cases, the depth is at least about 1/32, 1/16, 1/8, 1/4, 1/2, 3/4, 7/8, 15/16, or 31/32 of the thickness of the GDL. In some cases, the depth is at most about 1/32, 1/16, 1/8, 1/4, 1/2, 3/4, 7/8, 15/16, or 31/32 of the thickness of the GDL.

[00254] The one or more features can comprise various surface areas. The one or more features can extend across a portion of the surface of the anode channel. In some cases, a ratio of a projected surface area of the one or more features to a projected surface area of the anode channel is at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, the ratio of a projected surface area of the one or more features to a projected surface area of the anode channel is at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

[00255] The one or more features can comprise any number of features. In some cases, the one or more features can comprise two or more features. The one or more features can comprise at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 features. The one or more features can comprise at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100 features.

[00256] The one or more features can comprise various orientations. In some cases, at least a first segment of a first feature in two or more features is substantially parallel to a second segment of a second feature of the two or more features. In some cases, at least a first segment of a first feature in two or more features is substantially perpendicular to a second segment of a second feature of the two or more features. In some cases, at least a first segment of a first feature in two or more features is at an angle to a second segment of a second feature of the two or more features, wherein the angle is about between 0 and 90 degrees, between 0 and 30 degrees, between 15 and 75 degrees, or between 30 and 60 degrees. In some cases, two or more features can be connected or disconnected. In some cases, two or more features can intersect. A feature can be substantially parallel with the longest side of the anode channel. A feature can be substantially parallel with the shortest side of the anode channel. The one or more features can comprise various shapes. For example, the one or more features can comprise a substantially straight shape, a curved shape, a serpentine shape, or another shape.

[00257] FIG. 11 schematically illustrates various examples of cut configurations that may be utilized for an anode channel of a fuel cell. The cut configurations may comprise a plurality of cuts across a surface of the anode channel of the fuel cell. The plurality of cuts may comprise one or more cuts into the surface of the anode channel to reduce the buildup of nitrogen in the anode and facilitate the outflow of nitrogen from the fuel cell so that the nitrogen does not accumulate in the gas diffusion layer of the anode. It is noted herein that the expression “anode channel” may be construed as an “anode gas diffusion layer channel,” an “anode current collecting layer channel,” or a combination of both.

[00258] The cuts may comprise a depth extending into the anode channel ranging from about 0.01 millimeters to about 10 mm. In some embodiments, the depth is at least about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, or any value therebetween. In some embodiments, the depth is at most about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, or any value therebetween. In some embodiments, the depth is between 0.01 mm and about 10 mm, between about 0.05 mm and about 9 mm, between about 0.1 mm and about 8 mm, between 0.2 mm and about 7 mm, between about 0.3 mm and about 6 mm, between about 0.4 mm and about 5 mm, between 0.5 mm and about 4 mm, between about 0.6 mm and about 3 mm, between about 0.7 mm and about 2 mm, between 0.8 mm and about 1 mm, or between about 0.9 mm and about 10 mm. In some embodiments, the one or more cuts may comprise depths extending into the anode channel equal to the thickness of the anode channel.

[00259] In some embodiments, the one or more cuts may extend into the anode channel at a depth ranging from about 1/8 to about 1/2 of the thickness of the anode channel. In some embodiments, the depth is at least about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is at most about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is between 1/8 and about 1/2, between about 1/7 and about 1/3, between about 1/6 and about 1/4, or between 1/5 and about 1/2 of the thickness of the anode channel. For example, in an anode channel comprising a thickness of 2 mm, the cuts may comprise a depth ranging from about .25 mm to about 1 mm.

[00260] In some embodiments, the one or more cuts may extend into the anode channel at a depth ranging from about 1/2 to about 4/5 of the thickness of the anode channel. In some embodiments, the depth is at least about 1/2, about 2/3, about 3/4, about 4/5, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is at most about 1/2, about 2/3, about 3/4, about 4/5, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is between 1/2 and about 4/5, between about 2/3 and about 3/4, or between about 3/4 and about 4/5 of the thickness of the anode channel. For example, in an anode channel comprising a thickness of 2 mm, the cuts may comprise a depth ranging from about 1 mm to about 1.6 mm.

[00261] In some cases, some of the one or more cuts may extend into the anode channel at a different depth than others of the one or more cuts (e.g., a first set of cuts may comprise a depth of about 0.25 mm and a second set of cuts may comprise a depth of about 0.5 mm). In some cases, each of the one or more cuts may extend into the anode channel at the same depth.

[00262] In some cases, the fuel cell comprises an anode gas diffusion layer with one or more anode channels. In some embodiments, the one or more anode channels comprise one or more features. In some embodiments, the one or more features comprise (i) one or more cuts or grooves or (ii) one or more cutouts or openings configured to enhance diffusion and transport of the source material through the anode gas diffusion layer. In some embodiments, the one or more features are configured to direct a flow of nitrogen from the anode gas diffusion layer to out of the fuel cell so that nitrogen does not accumulate in the anode gas diffusion layer.

[00263] In some embodiments, a feature of the one or more features has a depth that is at least about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, or any value therebetween. In some embodiments, the depth is at most about 0.01 mm, about 0.05 mm, about 0.1 mm, about 0.2 mm, about 0.3 mm, about 0.4 mm, about 0.5 mm, about 0.6 mm, about 0.7 mm, about 0.8 mm, about 0.9 mm, about 1 mm, about 2 mm, about 3 mm, about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, or any value therebetween. In some embodiments, the depth is between 0.01 mm and about 10 mm, between about 0.05 mm and about 9 mm, between about 0.1 mm and about 8 mm, between 0.2 mm and about 7 mm, between about 0.3 mm and about 6 mm, between about 0.4 mm and about 5 mm, between 0.5 mm and about 4 mm, between about 0.6 mm and about 3 mm, between about 0.7 mm and about 2 mm, between 0.8 mm and about 1 mm, or between about 0.9 mm and about 10 mm.

[00264] In some cases, the cut configurations may comprise one or more cuts extending across at least a portion of the surface of the anode channel. In some cases, the one or more cuts may be parallel to each other. In other cases, the one or more cuts may not or need not be parallel to each other. In some cases, the cuts may comprise one or more horizontal cuts extending along a width of the anode channel and/or one or more vertical cuts extending along a length of the anode channel. The one or more horizontal cuts and the one or more vertical cuts may or may not intersect with each other. In some cases, the surface of the anode channel may comprise one or more sets of cut configurations. The one or more sets of cut configurations may be located on different portions or regions of the surface of the anode channel. In some cases, the one or more sets of cut configurations may be distributed across different quadrants of the surface of the anode channel. In some cases, the one or more cuts may be disposed at an angle relative to each other. In some cases, the one or more cuts may be disposed at a plurality of different angles relative to each other.

[00265] FIG. 12 schematically illustrates various examples of cutout configurations that may be utilized for an anode channel of a fuel cell. The cutout configurations may comprise a plurality of cutouts (e.g., openings) across a surface of the anode channel of the fuel cell. The plurality of cutouts may comprise one or more cutouts in the surface of the anode channel to reduce the buildup of nitrogen in the anode and facilitate the outflow of nitrogen from the fuel cell so that the nitrogen does not accumulate in the gas diffusion layer of the anode. In some cases, a cutout area ratio (a ratio of (i) the removed area of the cutout to (ii) the original area of the surface of the anode channel; e.g., if 20% of the original area of the surface is removed, the cutout area ratio may be 0.2) may range from about 0.01 to about 0.5. In some cases, the cutout area ratio may range from about 0.3 to about 0.7. In some cases, the cutout area ratio may range from about 0.5 to about 0.9. In some embodiments, the cutout area ratio is at least about 0.01, about 0.05, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or any value therebetween. In some embodiments, the cutout area ratio is at most about 0.01, about 0.05, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or any value therebetween. In some embodiments, the cutout area ratio is between 0.01 and about 0.9, between about 0.05 and about 0.8, between about 0.1 and about 0.7, between 0.2 and about 0.6, between about 0.3 and about 0.5, or between about 0.4 and about 0.9. [00266] In some cases, the cutout configurations may comprise one or more cutouts extending across at least a portion of the surface of the anode channel. In some cases, the one or more cutouts may be parallel to each other. In other cases, the one or more cutouts may not or need not be parallel to each other. In some cases, the cutouts may comprise one or more horizontal cutouts extending along a width of the anode channel and/or one or more vertical cutouts extending along a length of the anode channel. The one or more horizontal cutouts and the one or more vertical cutouts may or may not intersect with each other. In some cases, the surface of the anode channel may comprise one or more sets of cutout configurations. The one or more sets of cutout configurations may be located on different portions or regions of the surface of the anode channel. In some cases, the one or more sets of cutout configurations may be distributed across different quadrants of the surface of the anode channel. In some cases, the one or more cutouts may be disposed at an angle relative to each other. In some cases, the one or more cutouts may be disposed at a plurality of different angles relative to each other.

[00267] In some embodiments, one or more grooves may extend into the anode channel at a depth ranging from about 1/8 to about 1/2 of the thickness of the anode channel. In some embodiments, the depth is at least about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is at most about 1/8, about 1/7, about 1/6, about 1/5, about 1/4, about 1/3, about 1/2, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is between 1/8 and about 1/2, between about 1/7 and about 1/3, between about 1/6 and about 1/4, or between 1/5 and about 1/2 of the thickness of the anode channel. For example, in an anode channel comprising a depth of 2 mm, the grooves may comprise a depth ranging from about .25 mm to about 1 mm. In some embodiments the one or more grooves may extend into the anode channel at a depth ranging from about 1/2 to about 4/5 of the thickness of the anode channel. In some embodiments, the depth is at least about 1/2, about 2/3, about 3/4, about 4/5, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is at most about 1/2, about 2/3, about 3/4, about 4/5, of the thickness of the anode channel, or any value therebetween. In some embodiments, the depth is between 1/2 and about 4/5, between about 2/3 and about 3/4, or between about 3/4 and about 4/5 of the thickness of the anode channel.

[00268] In some cases, the one or more grooves may extend into the anode channel at a depth that is different from the thickness of the anode channel. For example, in an anode channel comprising a depth of 2 mm, the grooves may comprise a depth ranging from about 1 mm to about 1.6 mm. In some cases, the one or more grooves may extend into the anode channel at a depth that is equal to the thickness of the anode channel. In some cases, a groove area ratio (the ratio of the area of the groove to the original area of the surface of the anode channel; e.g., if 20% of the original area comprises grooves, the groove area ratio may be 0.2) may range from about 0.01 to about 0.5. In some cases, the groove area ratio may range from about 0.3 to about 0.7. In some cases, the groove area ratio may range from about 0.5 to about 0.9. In some embodiments, the groove area ratio is at least about 0.01, about 0.05, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or any value therebetween. In some embodiments, the groove area ratio is at most about 0.01, about 0.05, about 0.1, about 0.2, about 0.3, about 0.4, about 0.5, about 0.6, about 0.7, about 0.8, about 0.9, or any value therebetween. In some embodiments, the groove area ratio is between 0.01 and about 0.9, between about 0.05 and about 0.8, between about 0.1 and about 0.7, between 0.2 and about 0.6, between about 0.3 and about 0.5, or between about 0.4 and about 0.9.

[00269] In some cases, the anode channel may comprise one or more cuts extending across at least a portion of the surface of the anode channel, one or more cutouts extending across at least a portion of the surface of the anode channel, one or more grooves extending across at least a portion of the surface of the anode channel, or any combination of cuts, cutouts and grooves.

[00270] In some cases, cuts may be preferred when a minimal cutout area ratio is preferred. In some cases, cutouts or grooves, or a combination thereof, may be preferred to achieve a higher rate of nitrogen purging (e.g., in comparison to cuts alone, which may achieve a relatively lower rate of nitrogen purging).

[00271] In some cases, combinations of one or more cuts, one or more cutouts, or one or more grooves may be employed when minimal cutout area ratios or minimal groove area ratios are preferred. In some cases, the minimal cutout area ratio or groove area ratio may be less than about 0.1. In some cases, the minimal cutout or groove area ratio may be less than about 0.2. In some cases, the minimal cutout or groove area ratio may be less than about 0.5.

[00272] In some cases, the anode channel may include both cuts and cutouts that extend into the anode channel at the same depth. In some cases, the anode channel may include both cuts and cutouts that extend into the anode channel at different depths.

[00273] In some cases, the cuts, cutouts, and grooves may be manufactured using one or more methods comprising at least one of stamping, laser cutting, engraving, chemical etching, and embossing. In some cases, the material removed by the cutouts may be recycled and used to form one or more channels in the one or more fuel cells.

[00274] In some cases, the fuel cell comprises a plurality of channels in fluid communication with the anode. The plurality of channels can be stacked in layers that are adjacent to one another. FIG. 6 schematically illustrates various examples of multi-layer anode channel designs that can be implemented to enhance fuel cell performance when the fuel cell is used to process a gaseous mixture of hydrogen and nitrogen to generate electrical energy. The multi-layer anode channel may comprise a plurality of layers. The plurality of layers may comprise at least a first layer and a second layer. At least one of the first layer and the second layer may comprise one or more cuts and/or one or more cutouts. In some cases, a first layer of the plurality of layers may not have any cuts or cutouts. In such cases, a second layer of the plurality of layers may comprise one or more cuts and/or one or more cutouts. In some cases, each of the first layer and the second layer may comprise one or more cuts and/or one or more cutouts. The cuts or cutouts of the first layer may or may not be aligned with the cuts or cutouts of the second layer. In some cases, the first layer may comprise a first set of cuts or cutouts and the second layer may comprise a second set of cuts or cutouts. The first and second sets of cuts or cutouts may or may not overlap each other. In some cases, the first and second sets of cuts or cutouts may comprise different patterns of cuts or cutouts. In some cases, the first and second sets of cuts or cutouts may comprise a combination of horizontal and vertical cuts or cutouts. In some cases, the first set of cuts or cutouts may comprise a plurality of horizontal cuts or cutouts, and the second set of cuts or cutouts may comprise a plurality of vertical cuts or cutouts. In some cases, the first set of cuts or cutouts may comprise a plurality of vertical cuts or cutouts, and the second set of cuts or cutouts may comprise a plurality of horizontal cuts or cutouts. At least one channel of the plurality of channels may not comprise (i.e., may lack) the one or more features comprising cuts, cutouts, and/or grooves.

[00275] As described above, in some cases, the one or more cuts and/or the one or more cutouts may extend across at least a portion of the surface of the anode channel. In some cases, the one or more cuts and/or the one or more cutouts may be parallel to each other. In other cases, the one or more cuts and/or the one or more cutouts may not or need not be parallel to each other. In some cases, the one or more cuts and/or the one or more cutouts may comprise one or more horizontal cuts or cutouts extending along a width of the anode channel and/or one or more vertical cuts or cutouts extending along a length of the anode channel. The one or more horizontal cuts or cutouts and the one or more vertical cuts or cutouts may or may not intersect with each other. In some cases, the surface of the anode channel may comprise one or more sets of cut configurations or cutout configurations. The one or more sets of cut configurations or cutout configurations may be located on different portions or regions of the surface of the anode channel. In some cases, the one or more sets of cut configurations or cutout configurations may be distributed across different quadrants of the surface of the anode channel. In some cases, the one or more cuts or cutouts may be disposed at an angle relative to each other. In some cases, the one or more cuts or cutouts may be disposed at a plurality of different angles relative to each other. In some cases, the one or more surface features may comprise one or more cuts or grooves on a surface of the one or more anode channels. The one or more cuts or grooves may extend across a portion of the surface of the one or more anode channels. In some cases, the one or more cuts or grooves may comprise two or more cuts or grooves that are parallel to each other. In other cases, the one or more cuts or grooves may comprise two or more cuts or grooves that are perpendicular to each other. In some cases, the one or more cuts or grooves may comprise two or more cuts or grooves that are disposed at an angle relative to each other. The angle may range from 0 degrees to about 90 degrees. In some cases, the angle may range from 0 degrees to about 45 degrees. In some cases, the angle may range from 0 degrees to about 30 degrees. In some cases, the angle may range from 0 degrees to about 15 degrees. In some cases, the one or more cuts or grooves may comprise two or more cuts or grooves that intersect with each other. In other cases, the one or more cuts or grooves may comprise two or more cuts or grooves that do not intersect.

[00276] In some cases, the one or more surface features may comprise one or more cutouts or openings on a surface of the one or more channels. The one or more cutouts or openings may extend across a portion of the surface of the one or more channels. In some cases, the one or more cutouts or openings may comprise two or more cutouts or openings that are parallel to each other. In other cases, the one or more cutouts or openings may comprise two or more cutouts or openings that are perpendicular to each other. In some cases, the one or more cutouts or openings may comprise two or more cutouts or openings that are disposed at an angle relative to each other. The angle may range from 0 degrees to about 90 degrees. In some cases, the angle may range from 0 degrees to about 45 degrees. In some cases, the angle may range from 0 degrees to about 30 degrees. In some cases, the angle may range from 0 degrees to about 15 degrees. In some cases, the one or more cutouts or openings may comprise two or more cuts or grooves that intersect with each other. In other cases, the one or more cutouts or openings may comprise two or more cutouts or openings that do not intersect.

[00277] In some embodiments, the gas diffusion layer of the anode may comprise one or more layers. In some cases, the one or more layers may comprise two or more layers. At least one layer of the two or more layers may comprise the one or more surface features. The one or more surface features may comprise (i) one or more cuts or grooves and/or (ii) one or more cutouts or openings. In some cases, the two or more layers may comprise a first layer comprising a first set of surface features and a second layer comprising a second set of surface features. In some cases, the first set of features and the second set of features may comprise a same or similar set of features. In other cases, the first set of features and the second set of features may comprise different sets of features. In some cases, the first set of features and the second set of features may overlap or partially overlap. In other cases, the first set of features and the second set of features may not or need not overlap.

[00278] In some cases, the anode gas diffusion layer may comprise a felt, a foam, a cloth, or a paper material. The felt, the foam, cloth, or the paper material may comprise, for example, graphite or another carbon-based material (e.g., carbon fibers). In some cases, the felt, the foam, the cloth, or the paper material may comprise a carbon felt, which may have similar features, properties, or characteristics with a cotton material. In some cases, the felt, the foam, the cloth, or the paper material may comprise a carbon paper, which may have similar features, properties, or characteristics to with a sheet of paper. In some cases, the felt, the foam, the cloth, or the paper material may comprise polytetrafluoroethylene (PTFE)-based material. In some cases, the felt, the foam, the cloth, or the paper material may comprise both carbon-based material and PTFE-based material. In some cases, the felt, the foam, the cloth, or the paper material may comprise hydrophobic properties with a water contact angle greater than about 90 degrees. In some cases, the felt, the foam, the cloth, or the paper material may comprise hydrophilic properties with a water contact angle less than about 90 degrees. In some cases, at least one part of the felt, the foam, the cloth, or the paper material may comprise hydrophobic properties and at least one other part of the felt, the foam, the cloth, or the paper material may comprise hydrophilic properties. The felt, foam, cloth, or paper materials may be porous, and may comprise different properties such as porosity, pore sizes, density, brittleness, and flexibility. In some cases, the felt, the foam, the cloth, or the paper material may conduct electrical currents. In some cases, the felt, the foam, the cloth, or the paper material may comprise at least one of surface texture, porosity, or pore size that is different between a first side and a second side. In some cases, the first side is front or top side and the second side is bottom or back side. In some cases, the first side faces the electrolyte and the second side faces the outside of the fuel cell. In some instances, a denser material may provide better performance for the anode gas diffusion layer. In some instances, a material that is too dense may increase gas diffusion or transport resistance. In some instances, a thinner material may provide better performance for the anode gas diffusion layer by decreasing gas diffusion or transport resistance. In some instances, a thinner material is preferred to increase the power density of the fuel cell. In some instances, a material that is too thin may increase gas diffusion or transport resistances. It is noted herein that the anode diffusion layer may comprise materials that are not felt, foam, paper, cloth, carbonbased materials, or PTFE-based material.

[00279] In cases where a single layer design is utilized, the material for the gas diffusion layer may need to be porous in order to diffuse hydrogen through the gas diffusion layer. In cases where a multi-layer design is utilized, the membrane side of the gas diffusion layer may comprise a porous sheet material and the current collecting side (where the channels are placed) may comprise any current conducting sheet material, such as a metal, copper, nickel, zinc, platinum, aluminum, steel, titanium, gold, or carbon-based material. In some cases, current conducting sheet may comprise any current conducting sheet material with one or more coatings of different current conducting materials.

[00280] In some cases, the felt, the foam, the cloth, or the paper material may comprise a carbon paper. The carbon paper may be manufactured by burning a carbon-based polymer sheet. The carbon felt, foam, cloth, or paper material may not or need not comprise a crystalline structure.

Fuel Cell Exit Flow

[00281] In some cases, exit flows may exit one or more fuel cells. The exit flow from the fuel cells may comprise H2, N2, O2, and/or one or more reaction byproducts (e.g., water). An exit flow from the anode channel can comprise H2, N2, ammonia (e.g., trace ammonia from ammonia reforming), water, or any combination thereof. An exit flow from the cathode channel can comprise O2, N2, water, or any combination thereof. In some cases, the fuel cell exit flow may comprise unconverted hydrogen from the fuel cells (hydrogen that is not consumed by the fuel cell and that is not converted into protons and electrons at the electrolyte membrane). In some cases, the fuel cell exit flow may comprise unconverted hydrogen from the exit flow of the anode channel of the fuel cells (an anode offgas). In some cases, the unconverted hydrogen may be directed back to the one or more reactors for combustion heating to heat the reactors for further ammonia decomposition. In some cases, the fuel cell exit flow may comprise unconverted hydrogen from the fuel cells, unconverted ammonia from the reactors, or unadsorbed ammonia from the adsorption towers. In some cases, the unconverted hydrogen from the fuel cells and the unconverted or unadsorbed ammonia from the reactors or the adsorption towers may be directed back to the one or more reactors for combustion heating to heat the reactors for further ammonia decomposition. In some cases, the unconverted O2 from the exit flow of the cathode channel may be directed to the one or more reactors for combustion heating to heat the reactors for ammonia decomposition.

[00282] In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen at most about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging from at least about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.5 to 0.8. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.4 to 0.7. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.3 to 0.6. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.2 to 0.5. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.1 to 0.4. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.05 to 0.3. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of hydrogen ranging about from 0.3 to 0.4.

[00283] In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging from at most about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.991, 0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, or 0.999. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging from at least about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, 0.991,

0.992, 0.993, 0.994, 0.995, 0.996, 0.997, 0.998, or 0.999. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging about from 0.1 to 0.4. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging about from 0.3 to 0.6. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging about from 0.5 to 0.8. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging about from 0.6 to 0.9. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of nitrogen ranging about from 0.4 to 0.6. In some cases, a stream exiting one or more fuel cells may comprise at least two of hydrogen, nitrogen, water, or oxygen.

[00284] In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of ammonia ranging from at most about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9. In some cases, a stream exiting one or more fuel cells may comprise a volume fraction, a molar fraction, or a partial pressure fraction of ammonia ranging from at least about 0.0001, 0.0002, 0.0003, 0.0004, 0.0005, 0.0006, 0.0007, 0.0008, 0.0009, 0.001, 0.002, 0.003, 0.004, 0.005, 0.006, 0.007, 0.008, 0.009, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, or 0.9.

[00285] In some cases, a plurality of streams comprising unconverted hydrogen may exit from the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules. In some cases, the plurality of streams exiting from the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules may be directed to the one or more combustion heaters of the ammonia reformer. In some cases, the plurality of streams exiting from the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules have at least one stream that is different in flow rate, hydrogen mole fraction, nitrogen mole fraction, or water mole fraction from the other exit streams. In some cases, a plurality of streams exit from the one or more fuel cells, one or more fuel cell stacks, one or more fuel cell modules comprise flow rates within a selected tolerance based on a target flow rate (e.g., target flow rate to a single fuel cell, fuel cell stack, or fuel cell module). In some cases, the selected tolerance is at least about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500%. In some cases, the selected tolerance is at most about 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, or 500%.

[00286] In some cases, one or more streams exiting the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules may pass through one or more water collectors or condensers. In some cases, the one or more water collectors or condensers remove at least portion of water in the one or more streams exiting the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules. In some cases, the one or more water collectors or condensers remove at least portion of water in the one or more streams exiting the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules before providing the one or more streams exiting the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules to the one or more combustion heaters of the ammonia reformer. In some cases, the one or more streams exiting the one or more fuel cells, one or more fuel cell stacks, or one or more fuel cell modules comprise H2, N2, water, or O2.

Anode Gas Diffusion Layer Properties

[00287] FIGS. 15A-15B are schematic diagrams illustrating gas diffusion layers (GDLs) for an anode of a fuel cell. The fuel cell may be substantially similar to other fuel cells described herein (e.g., the fuel cells described with respect to FIGS. 1-14 and 16A-17C).

[00288] FIG. 15A illustrates a conventional anode GDL 1500, which may enable transport of nitrogen 1505 therein, and thereby dilute hydrogen 1504 provided to the anode catalyst 1502. This dilution of hydrogen is disadvantageous since the dilution may decrease the fuel cell hydrogen consumption rate and/or the fuel cell output voltage.

[00289] In contrast, FIG. 15B shows an advantageous anode GDL 1501, in accordance with one or more embodiments of the present disclosure. The anode GDL 1501 may comprise a porous material comprising one or more properties. The one or more properties may comprise a density, a pore size distribution, or particle size distribution. The porous material is configured to facilitate transport of hydrogen 1504 and impede transport of nitrogen 1505 (or water). The porous material may be a carbon-based or paper-based material.

[00290] In some embodiments, the pore size distribution may be configured so that a size of pores of the porous material decreases or increases (1) from a first side of the anode GDL 1501 adjacent to outside the fuel cell (2) to a second side of the anode GDL 1501 adjacent to the anode catalyst and the electrolyte (see, e.g., the direction indicated by arrow 1503).

[00291] FIGS. 15C is a schematic diagram illustrating the anode GDL 1501 shown in FIG. 15B comprising cuts 1506a-d and/or cutouts 1507a-d to prevent the accumulation of nitrogen, in accordance with one or more embodiments of the present disclosure. The cuts 1506a-d and/or cutouts 1507a-d may be substantially similar or substantially identical to the cuts and cutouts described with respect to FIGS. 3-7 and 11-13. Additionally, the anode GDL 1501 may comprise grooves as described with respect to FIGS. 3-7 and 11-13.

Reduction of Current Density Variability between Fuel Cell Stacks

[00292] FIGS. 16A-16B are schematic diagrams illustrating reduction of current density variability between fuel cell stacks 160 la- 1601c, in accordance with one or more embodiments of the present disclosure. Each of the fuel cell stacks 160 la- 1601c may be substantially similar to the fuel cell stack or module 601 described with respect to FIG. 6. Additionally, each of the fuel cell stacks 1601a-1601c may include a fuel cell that is substantially similar to other fuel cells described herein (e.g., the fuel cells described with respect to FIGS. 1-15C and 17A-17C).

[00293] As shown in FIG. 16A, the fuel cell stacks 160 la- 1601c may be electrically connected in a series arrangement, so that a current 1604 passes the fuel cell stacks 160 la- 1601c in series. The fuel cell stacks 160 la- 1601c may receive an anode feed 1602 (e.g., reformate stream 120 comprising an H2/N2 mixture) and consume the hydrogen therein. The fuel cell stacks 1601a-1601c may discharge an anode effluent 1603 (e.g., anode offgas 128) comprising hydrogen that is not consumed by the fuel cell stacks 1601a-c.

[00294] In some embodiments, the fuel cell stack 1601a that is closer to an inlet of the anode feed 1602 may consume the hydrogen therein, which may result in a higher current density than the fuel cell stacks 1601b and 1601c that are father from the inlet of the anode feed 1602. This variability in current density is disadvantageous, since the fuel cell stacks 1601b and 1601c that are father from the inlet of the anode feed 1602 may not output electrical power at full potential.

[00295] To overcome this problem, a physical property of each of the fuel cell stacks 160 la- 1601c may be different from others of the fuel cell stacks 1601a-c, so that a current density of the each of the fuel cell stacks 160 la- 1601c is the same as the others of the fuel cell stacks 1601a-1601c. This equalization (i.e., even distribution) of current density between the fuel cell stacks 160 la- 1601c may enable each of the fuel cell stacks 160 la- 1601c to output electrical power at full potential. In some embodiments, a physical property of at least one of the fuel cell stacks 1601a-c positioned upstream in the series arrangement is different from others of the fuel cell stacks 1601a-c positioned downstream in the series arrangement.

[00296] In some embodiments, the physical property comprises a fuel cell stack volume (e.g., the fuel cell stack 1601a closer to the inlet of the anode feed 1602 may be smaller in volume than the fuel cell stacks 1601b and 1601c).

[00297] In some embodiments, the physical property comprises an anode surface area of fuel cells in each fuel cell stack 1601a-1601c (e.g., the anode surface area of the fuel cells in stack 1601a (closer to the inlet of the anode feed 1602) may be smaller than the anode surface area of the fuel cells in stacks 1601b and 1601c). As shown in FIG. 16B, dielectric partitions 1605a-1605g may be positioned between fuel cell stacks 1601a-1601g. The dielectric partitions 1605a- 1605g may comprise, for example, a plastic material or a ceramic material. The dielectric partitions 1605a- 1605g may be configured to further equalize the current density between the fuel cell stacks 1601a-g (additionally or alternatively to the varied physical properties described previously).

[00298] In some embodiments, to equalize the current density between the fuel cell stacks 1601a-g, a thickness of the dielectric partitions 1605a-1605g may be varied, so that the dielectric partition 1605a that is positioned between the fuel cells stacks 1601a and 1601b is thicker than the dielectric partition 1605f positioned between the fuel cell stacks 160 If and 1601g.

[00299] In some embodiments, the fuel cell stacks 160 la- 1601g may be configured to output a (combined) power of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilowatts. The fuel cell stacks 1601a-1601g may be configured to output a (combined) power of at most about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilowatts. The fuel cell stacks 1601a-1601g may be configured to output a (combined) power of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 megawatts. The fuel cell stacks 1601a-1601g may be configured to output a (combined) power of at most about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 megawatts. The current density of each of the fuel cell stacks 1601a-1601g may comprise at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 amps per cm ² to at most about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 amps per cm ² . It is noted that the fuel cell stacks 1601a-1601g may comprise any number of fuel cell stacks, and each fuel cell stack 1601a-1601g may comprise any number of fuel cells.

Cylindrical Fuel Cells

[00300] FIGS. 17A-17C are schematic diagrams illustrating cylindrical fuel cells 1702, in accordance with one or more embodiments of the present disclosure. The cylindrical fuel cells 1702 may comprise a fuel cell that is substantially similar to other fuel cells described herein (e.g., the fuel cells described with respect to FIGS. 1-16B).

[00301] As shown in FIG. 17A, a cylindrical fuel cell array 1701 may comprise the cylindrical fuel cells 1702. The fuel cell array 1701 may include a skid or plate 1707 configured to attach, affix, or secure cylindrical fuel cells 1702. [00302] The cylindrical fuel cells 1702 may be in fluid communication with an anode inlet, which may distribute an anode feed 1703 (e.g., reformate stream 120 comprising an H2/N2 mixture) to the cylindrical fuel cells 1702 (via fluid lines and/or a manifold). The cylindrical fuel cells 1702 may receive and consume the hydrogen in the anode feed 1703. The anode inlet may be positioned adjacent to a first side (e.g., top side) of the fuel cell array 1701.

[00303] The cylindrical fuel cells 1702 may be in fluid communication with an anode outlet, which may discharge an anode effluent 1704 (e.g., anode offgas 128; comprising hydrogen that is not consumed by the cylindrical fuel cells 1702, as well as nitrogen and water) (via fluid lines and/or a manifold). The anode outlet may be positioned adjacent to a second side (e.g., bottom side) of the fuel cell array 1701 (that is opposite from the first side of the fuel cell array 1701).

[00304] The cylindrical fuel cells 1702 may be in fluid communication with a cathode inlet, which may distribute a cathode feed 1705 (e.g., air stream 118 comprising at least oxygen) to the cylindrical fuel cells 1702 (via fluid lines and/or a manifold). The cylindrical fuel cells 1702 may receive and consume the oxygen in the cathode feed 1705. The cathode inlet may be positioned adjacent to a third side (e.g., first lateral side) of the fuel cell array 1701.

[00305] The cylindrical fuel cells 1702 may be in fluid communication with a cathode outlet, which may discharge a cathode effluent 1706 (e.g., cathode offgas 504; comprising oxygen that is not consumed by the cylindrical fuel cells 1702, as well as water) (via fluid lines and/or a manifold). The cathode outlet may be positioned adjacent to a fourth side (e.g., a second lateral side) of the fuel cell array 1701 (that is opposite from the third side of the fuel cell array 1701).

[00306] As shown in FIG. 17B, each cylindrical fuel cell 1702 may comprise an electrochemical circuit comprising a cylindrical cathode and a cylindrical anode. The cylindrical cathode may comprise a cylindrical cathode current collector 1708, a cylindrical cathode GDL

1709, and a cylindrical cathode electrode (i.e., catalyst) 1710. The cylindrical anode may comprise a cylindrical anode electrode (i.e., catalyst) 1712, a cylindrical anode GDL 1713, and a cylindrical anode current collector 1714. A polymer electrolyte membrane (PEM) 1711 may be positioned between the cylindrical anode electrode 1712 and the cylindrical cathode electrode

1710.

[00307] In some embodiments, the cylindrical anode, the cylindrical cathode, and the PEM 1711 are positioned annularly with respect to a longitudinal axis at a center of each cylindrical fuel cell 1702. In some embodiments, the cylindrical anode, the cylindrical cathode, and the PEM 1711 are concentrically aligned with respect to the longitudinal axis. The cylindrical anode may be adjacent to inside the fuel cell 1702, and the cylindrical cathode may be adjacent to outside the fuel cell 1702.

[00308] In some embodiments, the cylindrical anode is positioned at a first radius with respect to the longitudinal axis, the cylindrical PEM 1711 is positioned at a second radius with respect to the longitudinal axis, and the cylindrical cathode is positioned at a third radius with respect to the longitudinal axis. The second radius may be greater than the first radius so that the cylindrical PEM 1711 is positioned farther from the longitudinal axis than the cylindrical anode. The third radius may be greater than the second radius and the first radius, so that the cylindrical cathode is positioned farther from the longitudinal axis than the cylindrical PEM 1711 and the cylindrical anode.

[00309] In some embodiments, each of the cathode current collector 1708, the cathode gas diffusion layer (GDL) 1709, and the cathode electrode 1710 comprises a thickness of at least about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, or 10 cm.

[00310] In some embodiments, each of the cathode current collector 1708, the cathode gas diffusion layer (GDL) 1709, and the cathode electrode 1710 comprises a thickness of at most about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, or 10 cm.

[00311] Each of the anode current collector 1714, the anode gas diffusion layer (GDL) 1713, and the anode electrode 1712 may comprise a thickness of at least about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, or 10 cm. [00312] Each of the anode current collector 1714, the anode gas diffusion layer (GDL) 1713, and the anode electrode 1712 may comprise a thickness of at most about 0.1 mm, 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1 mm, 2 mm, 3 mm, 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, or 10 cm.

[00313] A diameter of the cylindrical fuel cell 1702 may comprise at least about 1 millimeter, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm.

[00314] A diameter of the cylindrical fuel cell 1702 may comprise at most about 1 millimeter, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm. [00315] A length of the cylindrical fuel cell 1702 may comprise at least about 1 centimeter, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 50 cm, 1 m, 5 m, 10 m, 25 m, or 50 m.

[00316] A length of the cylindrical fuel cell 1702 may comprise at most about 1 cm, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 50 cm, 1 m, 5 m, 10 m, 25 m, or 50 m. [00317] In some embodiments, the cathode feed 1705 is adjacent or at the outside of the fuel cell 1702 and in fluid communication with the cylindrical cathode. The anode feed 1703 may be in fluid communication with the inside of the fuel cell 1702 and the cylindrical anode. A mole fraction of the hydrogen in the anode feed 1703 may comprise at least about 10, 20, 30, 40, 50, 60, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%, and at most about 10, 20, 30, 40, 50, 60, 70,

80, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99%. The cylindrical fuel cell may consume or utilize at least about 30, 40, 50, 60, 80, 85, 90, 95, or 99% of the hydrogen, and at most about 30, 40, 50,

60, 80, 85, 90, 95, or 99% of the hydrogen in the anode feed 1703. The anode feed 1703 may comprise a flow rate of about from 1.6*10' ⁵ kg/s to 2 kg/s (e.g., a flow rate of hydrogen in the anode feed 1703).

[00318] As shown in FIG. 17C, a plurality of cylindrical fuel cell arrays 1701a-1701f may be stacked together, and the power outputs of each of the fuel cell arrays 1701a-1701f may be combined (for example, to scale up a power system to power a large ship). The cylindrical fuel cell arrays 1701a-1701f may be attached to each other via a plurality of skids or plates 1707. [00319] The plurality of cylindrical fuel cell arrays 1701a-1701f may comprise at least about 2, 4, 6, 8, 10, 50, 100, 500, 1000, 5000, 5000, or 10,000 fuel cells 1702. In some embodiments, the plurality of cylindrical fuel cell arrays 1701a-1701f may comprise at most about 2, 4, 6, 8, 10, 50, 100, 500, 1000, 5000, 5000, or 10,000 fuel cells 1702. However, the present disclosure is not limited thereto, and the plurality of cylindrical fuel cell arrays 1701a- 170 If may comprise any number of fuel cells 1702. The combined power output of the fuel cells 1702 may comprise at least about 1 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 80 kW, 90 kW, 100 kW, 500 kW, 1 MW, 5 MW, 10 MW, 20 MW, 30 MW, 40 MW, 50 MW, 60 MW, 70 MW, 80 MW, 90 MW, or 100 MW. In some embodiments, the combined power output of the fuel cells 1702 may comprise at most about 1 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 80 kW, 90 kW, 100 kW, 500 kW, 1 MW, 5 MW, 10 MW, 20 MW, 30 MW, 40 MW, 50 MW, 60 MW, 70 MW, 80 MW, 90 MW, or 100 MW. However the present disclosure is not limited thereto, and the combined power output of the fuel cells 1702 may comprise any power output. [00320] The cylindrical geometry of the cylindrical fuel cells 1702 may enable a configuration that is similar to a Tubular Exchanger Manufacturers Association (TEMA) shell- and-tube heat exchanger, which may advantageously facilitate cooling of the fuel cells 1702 via heat transfer. The configuration may be similar to a bundle tube heat exchanger, plate heat exchanger, tube-in-tube heat exchanger, or a combination thereof. An intermediate cooling fluid, such as water or a glycol, may be used to cool the cylindrical fuel cells 1702.

HC Reforming Systems

[00321] FIGS. 18A-21B are block diagrams illustrating an HC reforming system 1800, in accordance with one or more embodiments of the present disclosure. The HC reforming system 1800 comprises an HC storage tank 1802, a heat exchanger 1806, one or more combustion- heated reformers 1808, a combustion heater 1809, one or more electrically-heated reformers 1810, an electric heater 1811, an air supply unit 1816, a filter 1822, and a fuel cell 1824.

[00322] The storage tank 1802 may be configured to store HC under pressure and/or at a low temperature. The storage tank 1802 may comprise a metallic material or a polymeric material. The tank 1902 may comprise one or more insulating layers (e.g., perlite or glass wool). In some cases, an additional heater may be positioned near, adjacent, at, or inside the storage tank 1802 to heat and/or pressurize the HC stored therein. In some embodiments, the HC may be stored with water (for example, 66% methanol and 33% water). In some embodiments, a separate tank storing water may be used to provide water for a reforming reaction and/or a water gas shift (WGS) reaction.

[00323] The heat exchanger 1806 may be configured to exchange heat between various input fluid streams and output fluid streams. For example, the heat exchanger 1806 may be configured to exchange heat between an incoming HC stream 1804 provided by the storage tank 1802 (e.g., relatively cold liquid methane) and a reformate stream 1820 (e.g., relatively warm H2 gas, or a mixture of H2 and CO2) provided by the reformers 1808 and 1810. The heat exchanger 1806 may be a plate heat exchanger, a shell-and-tube heat exchanger, or a tube-in-tube heat exchanger, although the present disclosure is not limited thereto.

[00324] The reformers 1808 and 1810 may be configured to generate and output the reformate stream 1820 comprising at least hydrogen (H2). The H2 may be generated by contacting the incoming HC stream 1804 with reforming catalyst 1830 positioned inside each of the reformers 1808 and 1810. The reformers 1808 and 1810 may be heated to a sufficient temperature range to facilitate HC reforming (for example, of from about 100 °C to about 800 °C). [00325] In some embodiments, the HC comprises an alkane, and the reforming reaction performed in the reformers 1808-1810 comprises:

CnH(2+2n) + nH2O ^nCO +(l+2n)H ₂ where n is an integer of at least one. For example, the HC may comprise methane (CH4), and the reforming reaction and WGS reaction performed in the reformers 1808-1810 comprises:

CH ₄ + H ₂ O -> CO + 3H ₂

The HC may comprise ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, an isomer thereof, or any combination thereof.

[00326] In some embodiments, the HC comprises an alcohol. For example, the HC may comprise methanol, and the reforming reaction performed in the reformers 1808-1810 comprises:

The HC may comprise ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, an isomer thereof, or any combination thereof.

[00327] In some embodiments, the HC comprises a liquid organic hydrogen carrier (LOHC). For example, the LOHC may comprise methylcyclohexane, and the reforming reaction performed in the reformers 1808-1810 comprises:

The HC may comprise cyclohexane (e.g., which may be reformed to benzene), methylcyclohexane (e.g., which may be reformed to toluene), decalin (e.g., which may be reformed to naphthalene), perhydro-N-ethylcarbazole (e.g., which may be reformed to N- ethyl carb azole), perhydrodibenzyltoluene (e.g., which may be reformed to dibenzyltoluene).

[00328] In some embodiments, the reformers 1808 and 1810 may comprise a plurality of reformers, which may fluidically communicate in various series and/or parallel arrangements. For example, an electrically-heated reformer 1810 may fluidically communicate in series or in parallel with a combustion-heated reformer 1808 (or vice versa) as a pair of reformers 1808- 1810. Such a pair of reformers 1808-1810 may fluidically communicate in parallel with other reformer 1808-1810 or pairs of reformers 1808-1810 (so that pairs of reformers 1808-1810 combine their outputs into a single reformate stream 1820), or may fluidically communicate in series with other reformers 1808-1810 or pairs of reformers 1808-1810.

[00329] In some embodiments, the number of combustion-heated reformers 1808 may be the same as the number of electrically-heated reformers 1810, and the reformers 1808-1810 may fluidically communicate in various series and/or parallel arrangements. For example, two electrically-heated reformers 1810 may fluidically communicate in series with two combustion- heated reformers 1808 (or vice versa).

[00330] In some embodiments, the number of combustion-heated reformers 1808 may be different from the number of electrically-heated reformers 1810 and the reformers 1808-1810 may fluidically communicate in various series and/or parallel arrangements. For example, two electrically-heated reformers 1810 may fluidically communicate in series with four combustion- heated reformers 1808 (or vice versa).

[00331] The combustion heater 1809 may be in thermal communication with the combustion-heated reformer 1808 to heat the reforming catalyst 1830 in the reformer 1808. The combustion heater 1809 may react at least part of the reformate stream 1820 (e.g., the H2) with an air stream 1818 (e.g., at least oxygen (O2)). The heat from the exothermic combustion reaction in the combustion heater 1809 may be transferred to the reforming catalyst 1830 in the reformer 1808. For example, the hot combustion product gas 1814 may contact walls of the reformer 1808, and the hot combustion product gas 1814 may be subsequently output from the combustion heater 1809 as combustion exhaust 1814. The combustion heater 1809 may comprise a separate component from the reformer 1808 (and may be slidably insertable or removable in the reformer 1808). In some cases, the combustion heater 1809 is a unitary structure with the combustion-heated reformer 1808 (and both the reformer 1808 and the heater 1809 may be manufactured via 3D printing and/or casting).

[00332] The air supply unit 1816 (e.g., one or more pumps and/or compressors) may be configured to supply the air stream 1818 (which may be sourced from the atmosphere, and may comprise at least about 20% oxygen by molar fraction). The air stream 1818 may comprise pure oxygen by molar fraction, or substantially pure oxygen by molar fraction (e.g., at least about 99% pure oxygen).

[00333] The electric heater 1811 may be in thermal communication with the electrically- heated reformer 1810 to heat the reforming catalyst 1830 in the reformer 1810. The electric heater 1811 may heat the reforming catalyst 1830 in the electrically-heated reformer 1810 by resistive heating or Joule heating. In some cases, the electrical heater 1811 may comprise at least a heating element (e.g., nichrome or ceramic) that transfers heat to the catalyst 1830 in the electrically-heated reformer 1810. In some cases, the electrical heater 1811 may comprise metal electrodes (e.g., copper or steel electrodes) that pass a current through the catalyst 1830 to heat the catalyst 1830 in the reformer 1810.

[00334] The filter 1822 may be configured to filter or remove trace hydrogen carrier in the reformate stream 1820. The filter 1822 may be configured to reduce the concentration of HC in the reformate stream 1820, for example, from greater than about 10,000 parts per million (ppm) to less than about 100 ppm. The filter 1822 may comprise a fluidized bed comprising a plurality of particles or pellets. The filter 1822 may be cartridge-based (for simple replaceability, for example, after the filter 1822 is saturated with HC). In some embodiments, the filter 1822 is configured to reduce the concentration of CO2 in the reformate stream 1820.

[00335] The filter 1822 may comprise an adsorbent (e.g., bentonite, zeolite, clay, biochar, activated carbon, silica gel, metal organic frameworks (MOFs), and other nanostructured materials). The adsorbent may comprise pellets, and may be stored in one or more columns or towers. In some instances, the filter 1822 may comprise an absorbent, a solvent-based material, and/or a chemical solvent.

[00336] In some embodiments, the filter 1822 comprises a multi-stage HC filtration system (e.g., water-based) comprising a plurality of filtration stages. The replacement of waterbased absorbents may be performed for continuous operation.

[00337] In some embodiments, the filter 1822 comprises a selective HC oxidation reactor including oxidation catalysts configured to react trace or residual HC in the reformate stream 1820 with oxygen (O2) to generate carbon dioxide (CO2) and water (H2O). The air stream 1818 (or a separate oxygen source) may be provided to the HC oxidation reactor to provide the oxygen for the oxidation reaction. The HC oxidation reactor may selectively combust the trace or residual amounts of hydrocarbon (e.g., the HC) while avoiding the combustion of H2.

[00338] The fuel cell 1824 may comprise an anode, a cathode, and an electrolyte between the anode and the cathode. The fuel cell 1824 may comprise a polymer electrolyte membrane fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a molten carbonate fuel cell (MCFC), a phosphoric acid fuel cell (PAFC), or an alkaline fuel cell (AFC), although the present disclosure is not limited thereto. The fuel cell 1824 may process the H2 in the reformate stream 1820 at an anode, and process the O2 in the air stream at a cathode, to generate electricity (to power an external electrical load). The fuel cell 1824 may be configured to receive hydrogen (e.g., at least part of the reformate stream 1820) via one or more anode inlets, and oxygen (e.g., at least part of the air stream 1818 or a separate air stream) via one or more cathode inlets.

[00339] In some embodiments, the fuel cell 1824 may output unconsumed hydrogen (e.g., as an anode off-gas) via one or more anode outlets, and/or may output unconsumed oxygen (e.g., as a cathode off-gas) via one or more cathode outlets. The anode off-gas and/or the cathode offgas may be provided to the combustion heater 1809 as reactants for the combustion reaction performed therein. In some embodiments, the anode off-gas and/or the cathode off-gas is recirculated to the fuel cell 1824.

[00340] As shown in FIGS. 18A-18B, the storage tank 1802 may be in fluid communication with the combustion-heated reformer 1808 and/or the electrically-heated reformer 1810 (e.g., using one or more lines or conduits). The storage tank 1802 may provide the incoming HC stream 1804 (for example, by actuating a valve). In some instances, the heat exchanger 1806 may facilitate heat transfer from the (relatively warmer) reformate stream 1820 to the (relatively cooler) incoming HC stream 1804 to preheat and/or vaporize the incoming HC stream 1804 (changing the phase of the HC stream 1804 from liquid to gas). The incoming HC stream 1804 may then enter the reformers 1808 and 1810 to be reformed into hydrogen (and, in some cases, CO2).

[00341] In some embodiments, the incoming HC stream 1804 may first be partially reformed by the electrically-heated reformer 1810 into a partially cracked reformate stream 1820 (e.g., comprising at least about 10% H2 by molar fraction) (for example, during a start-up or initiation process). Subsequently, the partially cracked reformate stream 1820 may be further reformed in the combustion-heated reformer 1808 to generate a substantially cracked reformate stream (e.g., comprising less than about 10,000 ppm of residual or trace HC by volume and/or greater than about 99% H2, or greater than about 99% H2/CO2 mixture, by molar fraction). Passing the HC stream 1804 through the electrically-heated reformer 1810 first, and then subsequently passing the HC stream 1804 through the combustion-heated reformer 1808, may advantageously result in more complete HC conversion (e.g., greater than about 99%).

[00342] In some embodiments, the incoming HC stream 1804 may first be partially reformed by the combustion-heated reformer 1808 into a partially cracked reformate stream 1820 (e.g., comprising at least about 10% H2, or at least about 10% H2/CO2 mixture, by molar fraction). Subsequently, the partially cracked reformate stream 1820 may be further reformed in the electrically-heated reformer 1810 to generate a substantially cracked reformate stream (e.g., comprising less than about 10,000 ppm of residual or trace HC by volume and/or greater than about 99% H2, or greater than about 99% H2/CO2 mixture, by molar fraction). Passing the HC stream 1804 through the combustion-heated reformer 1808 first, and then subsequently passing the HC stream 1804 through the electrically-heated reformer 1810, may advantageously result in more complete HC conversion (e.g., greater than about 99%).

[00343] In some cases, the incoming HC stream 1804 may first be preheated by the combustion exhaust 1814 and/or the combustion heater 1809. In some cases, the preheated incoming HC stream 1804 may then enter the reformers 1808 and 1810 to be reformed into hydrogen. [00344] In some embodiments, the incoming HC stream 1804 may first be reformed by the electrically-heated reformer 1810 to generate a partially or substantially cracked reformate stream 1820 (for example, during a start-up or initiation process). Subsequently, at least part of the partially or substantially cracked reformate stream 1820 generated by the electrically-heated reformer 1810 may be combusted as a combustion fuel to heat at least one combustion heater 1809 of the one or more combustion-heated reformers 1808.

[00345] In some cases, power input to the electric heater 1811 of the electrically-heated reformer 1810 may be reduced or entirely turned off based on a temperature of the combustion- heated reformer 1808 and/or the combustion heater 1809 being equal to or greater than a target temperature (e.g., in a target temperature range). In some cases, power input to the electric heater 1811 of the electrically-heated reformer 1810 may be reduced or entirely turned off based on a flow rate of the incoming HC stream 1804 being equal to or greater than a target flow rate range.

[00346] As shown in FIG. 19, the filter 1822 may be configured to remove trace HC in the reformate stream 1820 and output a filtered reformate stream 1823. The filtered reformate stream 1823 may then be provided to the combustion heater 1809 to combust for heating the reformer 1808 (i.e., by auto-thermal reforming).

[00347] As shown in FIG. 20, the filtered reformate stream 1823 may be provided to the fuel cell 1824 to generate electrical power 1826. An external load (e.g., an electrical motor to power a transport vehicle, or a stationary electrical grid) may utilize the electrical power 1826. The fuel cell 1824 may provide the anode off-gas 1828 (e.g., containing unconsumed or unconverted hydrogen) to the combustion heater 1809 to combust for self-heating.

[00348] In some embodiments, the HC reforming system 1800 includes a battery (so that the system 1800 is a hybrid fuel cell-battery system). The battery may be configured to power an external load in addition to the fuel cell 1824. The fuel cell 1824 may be configured to charge the battery (for example, based a charge of the battery being less than a threshold charge).

[00349] As shown in FIG. 21 A, a pressure swing adsorber (PSA) 1827 may be configured to adsorb HC and/or CO2 in the filtered reformate stream 1823 (or the reformate stream 1820) to further purify the filtered reformate stream 1823. The PSA may be configured to increase the molar fraction of H2 in the filtered reformate stream 1823 (or the reformate stream 1820), and decrease the molar fractions of HC and/or CO2 in the filtered reformate stream 1823 (or the reformate stream 1820). A PSA exhaust stream 1828b comprising H2 (and which may additionally comprise HC and/or CO2) may then be provided to the combustion heater 1809 to combust for self-heating the reformer 1808 (i.e., by auto-thermal reforming). Additionally, a purified reformate stream 1829 may be provided to the fuel cell 1824 to generate the electrical power output 1826.

[00350] As shown in FIG. 21B, a flow distributor 1815 may be configured to distribute at least portion 1828c of the reformate stream 1820 (or the filtered reformate stream 1823) to the combustion heater 1809 as a combustion fuel. The flow distributor 1830 may comprise, for example, one or more flow control units (e.g., one or more valves, one or more pumps, one or more flow regulators, etc.). A remaining reformate stream 1817 may be provided to various chemical or industrial processes, including, but not limited to, steel or iron processing, combustion engines, combustion turbines, hydrogen storage, hydrogen for chemical processes, hydrogen fueling stations, etc. In some cases, the remaining reformate stream 1817 can be supplied as a pilot, auxiliary, or main fuel to the combustion engines or combustion turbines.

[00351] In some embodiments, the reformate stream 1820, the filtered reformate stream 1823, the purified reformate stream 1829, and/or the remaining reformate stream 1817 may be provided to an internal combustion engine (ICE). Heat emitted by the ICE may be used to heat the reformer 1808 and/or the reformer 1810 (e.g., using a heat exchanger).

[00352] In some embodiments, the reformate stream 1820, the filtered reformate stream 1823, the purified reformate stream 1829, and/or the remaining reformate stream 1817 may be used directly for chemical or industrial processes (e.g., to reduce iron), storage (e.g., hydrogen storage), and/or hydrogen fueling stations.

[00353] In any of embodiments and/or configurations described with respect to FIGS. 18A-21B, the fuel cell 1824 may be absent, and at least part of the reformate 1820 may be combusted to maintain an auto-thermal reforming process. The remaining reformate 1820 (that is not combusted) may be provided for chemical or industrial processes, storage (e.g., hydrogen storage), and/or hydrogen fueling stations. In some cases, the remaining reformate stream 1820 is provided to an ICE. In some cases, heat emitted by the ICE may provide at least part or all of the heat required for HC reforming in the reformer 1808 and/or the reformer 1810. Any of the embodiments, configurations and/or components described with respect to FIGS. 18A-4B, may be partially or entirely powered by exhaust heat from a combustion engine.

Controller and Sensors

[00354] FIGS. 22A-22I are block diagrams illustrating utilization of a controller 2200 (e.g., computer or computing device), sensors P1-P10, Tl-Tl l, FM1-FM11, HCC1-HCC10, HC1-HC5 and flow control units FCU1-FCU11 to control the HC reforming system 1800 shown in FIGS. 19A-21B, in accordance with one or more embodiments of the present disclosure. [00355] As shown in FIG. 22A, the controller 2200 may comprise one or more processors 2202 and a memory 2204. The one or more processors 2202 may comprise one or more processing or logic elements (e.g., one or more micro-processor devices, one or more central processing units (CPUs), one or more graphics processing units (GPUs), one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)), and may be configured to execute, perform or implement algorithms, modules, processes and/or instructions (e.g., program instructions stored in memory). The one or more processors 2202 may be embodied in an embedded system (for example, as part of a terrestrial vehicle, an aerial vehicle, a marine vehicle, a stationary device, etc.). The memory 2204 may be configured to store program instructions executable, performable or implementable by the associated one or more processors 2202. For example, the memory medium 2204 may comprise a non-transitory memory medium, and may comprise, but is not limited to, a read-only memory (ROM), a random-access memory (RAM), a magnetic or optical memory device (e.g., disk), a magnetic tape, a solid-state drive and the like.

[00356] The controller 2200 may be in electronic communication with at least one of the sensors P1-P10, Tl-Tl l, FM1-FM11, HCC1-HCC10, HC1-HC5, and flow control units FCU1- FCU11 to monitor, measure, and/or control one or more characteristics or parameters of the HC reforming system 1800. For example, the controller 2200 may be connected by wire, or wirelessly, with the sensors P1-P10, Tl-Tl l, FM1-FM11, HCC1-HCC10, and HC1-HC5, and flow control units FCU1-FCU11.

[00357] A module 2214 stored in the memory 2204 may be configured to initiate or stop the monitoring or measurement of the HC reforming system 1800. A module 2216 may be configured to control components of the HC reforming system 1800 based on the monitored data (for example, by modulating heating power to the heaters 1809 and 1811, by modulating power output of the fuel cell 124, etc.). The modules 2214 and/or 2216 may be implemented using a graphical user interface, such that a user of the controller 2200 may view the monitored data (e.g., via one or more tables or charts) and/or manually control the HC reforming system 1800. In some embodiments, the modules 2214 and/or 2216 may automatically control the HC reforming system 1800 based on the measured on monitored data. It is noted that the modules 2214 and 2216 may be the same module (e.g., instead of being different modules).

[00358] The flow rate sensors FM1-FM11 may be configured to monitor or measure a flow rate (e.g., unit volume or unit mass per unit time) of a fluid (liquid or gas) in any component of the HC reforming system 1800, and transmit data associated with the flow rate measurement to be stored in the memory 204. [00359] The temperature sensors Tl-Tl l may be configured to detect a temperature (e.g., in Celsius or Kelvin) of any component of the HC reforming system 1800 (for example, the walls of the reformers 1808-1810 or the walls of the heaters 1809-1811), or may be configured to detect the temperature of a fluid (liquid or gas) in any component of the HC reforming system 1800, and transmit data associated with the temperature measurement to be stored in the memory 204.

[00360] The pressure sensors Pl -P10 may be configured to detect a pressure (e.g., gauge pressure (barg) or absolute pressure (bara)) of a fluid stream (liquid or gas) in any component of the HC reforming system 1800, and transmit data associated with the pressure measurement to be stored in the memory 204.

[00361] The concentration sensors HCC1-HCC10 and HC1-HC5 may be configured to detect a concentration (e.g., in parts per million) of a fluid (liquid or gas) in any component of the HC reforming system 1800, and transmit data associated with the concentration measurement to be stored in the memory 204.

[00362] Referring now to FIG. 22B, the pressure sensors Pl -P10 may be positioned in various components and/or fluid lines of the HC reforming system 1800. The pressure sensor Pl may be configured to measure the pressure of HC stored in the tank 1802. The pressure sensor P2 may be configured to measure the pressure of the incoming HC stream 1804 before the stream 1804 enters the heat exchanger 1806. The pressure sensor P3 may be configured to measure the pressure of the incoming HC stream 1804 after the stream 1804 exits the heat exchanger 1806. The pressure sensor P4 may be configured to measure the pressure of the air stream 1818 after the stream 1818 exits the air supply unit 1816. The pressure sensor(s) P5 may be configured to measure the pressure of fluid at one or more inlets, one or more outlets, and/or inside of the reformers 1808-1810 and/or the combustion heater 1809. For example, the pressure sensor(s) P5 may be configured to measure the pressure of the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808-1810, and/or the substantially cracked reformate stream 1820 at the outlets of the reformers 1808-1810. In another example, the pressure sensor(s) P5 may be configured to measure the pressure of the reformate stream 1820 and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The pressure sensor P6 may be configured to measure the pressure of the reformate stream 1820 after the reformate stream exits the reformer 1808-1810 and before the reformate stream 1820 enters the heat exchanger 1806. The pressure sensor(s) P7 may be configured to measure the pressure at one or more inlets, one or more outlets, and/or inside the filter 1822. The pressure sensor P8 may be configured to measure the pressure of the filtered reformate stream 1823 before the stream 1823 enters the fuel cell 1824. The pressure sensor(s) P9 may be configured to measure the pressure at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The pressure sensor PIO may be configured to measure the pressure of the anode off-gas 1828 after the off-gas 1828 exits the fuel cell 1824 and/or before the off-gas 1828 enters the combustion heater 1809.

[00363] Referring now to FIG. 22C, the temperature sensors Tl-Tl 1 may be positioned in various components and/or fluid lines of the HC reforming system 1800. The temperature sensor T1 may be configured to measure the temperature of HC stored in the tank 1802. The temperature sensor T2 may be configured to measure the temperature of the incoming HC stream 1804 before the stream 1804 enters the heat exchanger 1806. The temperature sensor T3 may be configured to measure the temperature of the incoming HC stream 1804 after the stream 1804 exits the heat exchanger 1806. The temperature sensor T4 may be configured to measure the temperature of the air stream 1818 after the stream 1818 exits the air supply unit 1816. The temperature sensor T5 may be configured to measure the temperature of fluid at one or more inlets, one or more outlets, and/or inside of the reformers 1808-1810 and/or the combustion heater 1809. For example, the temperature sensor T5 may be configured to measure the temperature of the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808-1810, and/or the substantially cracked reformate stream 1820 at the outlets of the reformers 1808-1810. In another example, the temperature sensor T5 may be configured to measure the temperature of the reformate stream 1820 and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The temperature sensor T6 may be configured to measure the temperature of the reformate stream 1820 after the reformate stream exits the reformer 1808- 1810 and before the reformate stream 1820 enters the heat exchanger 1806. The temperature sensor T7 may be configured to measure the temperature at one or more inlets, one or more outlets, and/or inside the filter 1822. The temperature sensor T8 may be configured to measure the temperature of the filtered reformate stream 1823 before the stream 1823 enters the fuel cell 1824. The temperature sensor T9 may be configured to measure the temperature at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The temperature sensor T10 may be configured to measure the temperature of the anode off-gas 1828 after the off-gas 1828 exits the fuel cell 1824 and before the off-gas 1828 enters the combustion heater 1809. The temperature sensor Ti l may be configured to measure the temperature at one or more inlets, one or more outlets, and/or inside the heat exchanger 1806).

[00364] It is noted that the temperature sensors Tl-Tl l may be configured to measure temperatures of the walls of the components and/or fluid lines of the HC reforming system 1800 (as opposed to directly measuring the temperature of the fluids passing therethrough, for example, by physically contacting the sensors with the fluid streams).

[00365] Referring now to FIG. 22D, the flow rate sensors FM1-FM11 (e.g., comprising flow meters or flow controllers) may be positioned in various components and/or fluid lines of the HC reforming system 1800. FM1-FM11 may comprise one or more valves, one or more regulators, or one or more flow rate sensors configured to monitor and/or control the flow rates of fluid streams of the HC reforming system 1800. The flow meter FM1 may be configured to measure the flow rate of the incoming HC stream 1804 before the stream 1804 enters the heat exchanger 1806. The flow meter FM2 may be configured to measure the flow rate of the incoming HC stream 1804 after the stream 1804 exits the heat exchanger 1806. The flow meter FM3 may be configured to measure the flow rate of the air stream 1818 at or inside the air supply unit 1816. The flow meter FM4 may be configured to measure the flow rate of the air stream 1818 after the stream 1818 exits the air supply unit 1816. The flow meter FM5 may be configured to measure the flow rate of fluid at one or more inlets, one or more outlets, and/or inside of the reformers 1808-1810 and/or the combustion heater 1809. For example, the flow meter FM5 may be configured to measure the flow rate of the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808-18180, and/or the substantially cracked reformate stream 120 at the outlets of the reformers 1808-1810. In another example, the flow meter FM5 may be configured to measure the flow rate of the reformate stream 1820 or anode off-gas 1828 and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The flow meter FM6 may be configured to measure the flow rate of the reformate stream 1820 after the reformate stream exits the reformer 1808-1810 and before the reformate stream 1820 enters the heat exchanger 1806. The flow meter FM7 may be configured to measure the flow rate at one or more inlets, one or more outlets, and/or inside the filter 1822. The flow meter FM8 may be configured to measure the flow rate of the filtered reformate stream 1823 before the stream 1823 enters the fuel cell 1824. The flow meter FM9 may be configured to measure the flow rate at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The flow meter FM10 may be configured to measure the flow rate of the anode off-gas 1828 after the off- gas 1828 exits the fuel cell 1824 and before the off-gas 1828 enters the combustion heater 1809. The flow meter FM11 may be configured to measure the one or more flow rates the one or more inlets, one or more outlets, or one or more locations in the heat exchanger 1806.

[00366] It is noted that, in some embodiments, the flow rate meters FM1-FM11 may comprise pumps, valves, blowers, compressors, or other fluid supply device, and the respective flow rate measurements may be performed by correlating a parameter of the fluid supply device with the flow rate. For example, the flow meter FM3 may be the air supply unit 1816 itself. If the air supply unit 1816 comprises a valve, the flow rate may be measured by correlating a size of an opening of the valve and/or one or more pressure measurements in the air supply unit 1816. If the air supply unit comprises a pump or a compressor, the flow rate may be measured by at least partly correlating a revolutions-per-minute (RPM) of the pump or the compressor.

[00367] Referring now to FIG. 22E, the HC sensors HCC1-HCC10 may be positioned in various components and/or fluid lines of the HC reforming system 1800. The HC sensor HCC1 may be configured to measure the concentration of HC in the storage tank 1802. The HC sensor HCC2 may be configured to measure the concentration of HC in the incoming HC stream 1804 before the stream 1804 enters the heat exchanger 1806. The HC sensor HCC3 may be configured to measure the concentration of HC in the incoming HC stream 1804 after the stream 1804 exits the heat exchanger 1806. The HC sensor HCC4 may be configured to measure the concentration of HC at one or more inlets, one or more outlets, and/or inside of the reformers 1808-1810 and/or the combustion heater 1809. For example, the HC sensor HCC4 may be configured to measure the concentration of HC in the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808- 1810, and/or the substantially cracked reformate stream 1820 at the outlets of the reformers 1808-1810. In another example, the HC sensor HCC4 may be configured to measure the concentration of HC in the reformate stream 1820 and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The HC sensor HCC5 may be configured to measure the concentration of HC in the reformate stream 1820 after the reformate stream exits the reformer 1808-1810 and before the reformate stream 1820 enters the heat exchanger 1806. The HC sensor HCC6 may be configured to measure the concentration of HC at one or more inlets, one or more outlets, and/or inside the filter 1822. The HC sensor HCC7 may be configured to measure the concentration of HC in the filtered reformate stream 1823 before the stream 1823 enters the fuel cell 1824. The HC sensor HCC8 may be configured to measure the concentration of HC at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The HC sensor HCC9 may be configured to measure the concentration of HC in the anode off-gas 1828 after the off-gas 1828 exits the fuel cell 1824 and before the off-gas 1828 enters the combustion heater 1809. The HC sensor HCC10 may be configured to measure the concentration of HC at one or more inlets, one or more outlets, and/or inside the heat exchanger 1806.

[00368] Referring now to FIG. 5F, the hydrogen concentration sensors HC1-HC5 positioned in various components and/or fluid lines of the HC reforming system 1800. The hydrogen concentration sensor HC1 may be configured to measure the concentration of hydrogen at one or more inlets, one or more outlets, and/or inside of the reformers 1808-1810 and/or the combustion heater 1809. For example, the hydrogen concentration sensor HC1 may be configured to measure the concentration of hydrogen in the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808-1810, and/or the substantially cracked reformate stream 1820 at the outlets of the reformers 1808-1810. In another example, the hydrogen concentration sensor HC1 may be configured to measure the concentration of hydrogen in the reformate stream 1820, the fuel cell off-gas 1828, and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The hydrogen concentration sensor HC2 may be configured to measure the concentration of hydrogen in the reformate stream 1820 after the reformate stream exits the reformer 1808-1810 and before the reformate stream 1820 enters the heat exchanger 1806. The hydrogen concentration sensor HC3 may be configured to measure the concentration of hydrogen in the filtered reformate stream 1823 before the stream 1823 enters the fuel cell 1824. The hydrogen concentration sensor HC4 may be configured to measure the concentration of hydrogen at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The hydrogen concentration sensor HC5 may be configured to measure the concentration of hydrogen in the anode off-gas 1828 after the off-gas 1828 exits the fuel cell 1824 and before the off-gas 1828 enters the combustion heater 1809.

[00369] Referring now to FIG. 22G, the flow control units FCU1-FCU11 may be positioned in various components and/or fluid lines of the HC reforming system 1800. FCU1- FCU11 may configured to monitor and/or control (i.e., increase, decrease, modulate, or maintain) one or more flow rates and/or one or more pressures of the HC reforming system 1800. FCU1-FCU11 may comprise one or more pressure drop elements configured to reduce pressure, one or more pumps, one or more check valves, one or more one-way valves, one or more three- way valves, one or more restrictive orifices, one or more valves, one or more flow regulators, one or more pressure regulators, one or more back pressure regulators, one or more pressure reducing regulators, one or more back flow regulators, one or more flow meters, one or more flow controllers, or any combination thereof. In some cases, the flow control units FCU1- FCU11 may be controlled manually, automatically, or electronically.

[00370] The flow control unit FCU1 may be configured to measure and/or control the flow rate and/or pressure of the incoming HC stream 1804 before the stream 1804 enters the heat exchanger 1806. The flow control unit FCU2 may be configured to measure and/or control the flow rate and/or pressure of the incoming HC stream 1804 after the stream 1804 exits the heat exchanger 1806. The flow control unit FCU3 may be configured to measure and/or control the flow rate and/or pressure of the air stream 1818 at or inside the air supply unit 1816. The flow control unit FCU4 may be configured to measure and/or control the flow rate and/or pressure of the air stream 1818 after the stream 1818 exits the air supply unit 1816. The flow control unit FCU5 may be configured to measure and/or control the flow rate and/or pressure of fluid at one or more inlets, one or more outlets, and/or inside the reformers 1808-1810 and/or the combustion heater 1809. For example, the flow control unit FCU5 may be configured to measure and/or control the flow rate and/or pressure of the incoming HC stream 1804 at the inlets of the reformers 1808-1810, the partially cracked reformate stream 1820 inside the reformers 1808- 1810, and/or the substantially cracked reformate stream 1820 at the outlets of the reformers 1808-1810. In another example, the flow control unit FCU5 may be configured to measure and/or control the flow rate and/or pressure of the reformate stream 1820 or anode off-gas 1828 and/or the air stream 1818 at the inlets of the combustion heater 1809, the combustion product gas 1814 inside the combustion heater 1809, and/or the combustion exhaust 1814 at the outlets of the combustion heater 1809. The flow control unit FCU6 may be configured to measure and/or control the flow rate and/or pressure of the reformate stream 1820 after the reformate stream exits the reformer 1808-1810 and before the reformate stream 1820 enters the heat exchanger 1806. The flow control unit FCU7 may be configured to measure and/or control the flow rate and/or pressure at one or more inlets, one or more outlets, and/or inside the filter 1822. The flow control unit FCU8 may be configured to measure and/or control the flow rate and/or pressure of the filtered reformate stream 1823 before the stream 1823 enters the fuel cell. The flow control unit FCU9 may be configured to measure and/or control the flow rate and/or pressure at one or more inlets, one or more outlets, and/or inside the fuel cell 1824. The flow control unit FCU10 may be configured to measure and/or control the flow rate and/or pressure of the anode off-gas 1828 after the off-gas 1828 exits the fuel cell 1824 and before the off-gas 1828 enters the combustion heater 1809. The flow control unit FM11 may be configured to measure and/or control the flow rate and/or pressure at one or more inlets, one or more outlets, and/or inside the heat exchanger 1806.

[00371] It is noted that, in some embodiments, the flow control units FCU1-FCU11 may comprise pumps, valves, blowers, compressors, or other fluid supply devices, and the respective flow rate measurements may be performed by correlating a parameter of the fluid supply device with the flow rate. For example, the flow control unit FCU3 may be the air supply unit 1816 itself. If the air supply unit 1816 comprises a valve, the flow rate may be measured by correlating a size of an opening of the valve and/or one or more pressure measurements in the air supply unit 1816. If the air supply unit 1816 comprises a pump or a compressor, the flow rate may be measured by at least partly correlating a revolutions-per-minute (RPM) of the pump or the compressor. In some cases, the flow control unit FCU1-FCU11 and the flow meter FM1- FM11 are interchangeable and/or may have one or more identical or similar functionalities.

[00372] In some instances, the flow control units FCU1-FCU11 and/or flow rate meters FM1-FM11 may maintain a flow rate to a target flow rate within a selected tolerance. In some instances, the selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some instances, the selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some instances, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and about 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance may be less than 20%.

[00373] In some cases, the flow control units FCU1-FCU11 and/or flow rate meters FM1- FM11 may increase a flow rate to a target flow rate at a predefined ramp-up rate (within a selected tolerance). In some cases, the selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some cases, the selected tolerance may be less than 20%.

[00374] In some cases, the flow control units FCU1-FCU11 and/or flow rate meters FM1- FM11 may decrease a flow rate to a target flow rate at a predefined ramp-down rates (within a selected tolerance). In some cases, the selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some cases, the selected tolerance may be less than 20%. [00375] Referring now to FIG. 22H, one or more pressure regulators may be positioned in various components and/or fluid lines of the HC reforming system 1800. For example, a back pressure regulator BPR1 (or a pressure reducing regulator PRR1) may be configured to maintain a pressure of the reformate stream 1820 after the reformate stream exits the reformer 1808-1810, after (or before) the reformate stream 1820 enters the heat exchanger 1806, or before the reformate stream 1820 enters the filter 1822. A back pressure regulator BPR2 (or a pressure reducing regulator PRR2) may be configured to maintain a pressure of the filtered reformate stream 1823 after the reformate stream 1823 exits the filter 1822. A back pressure regulator BPR3 (or a check valve CV1) may be configured to maintain a pressure of the anode off-gas 1828.

Fault Detection

[00376] Referring now to FIG. 221, a fault detection module 2214 may be stored in the memory 2204 of the controller 2200 and may be configured to detect one or more faults in the HC reforming system 1800 (e.g., by utilizing the sensors P1-P10, Tl-Tl l, FM1-FM11,HCC1- HCC10, and HC1-HC5,). The faults may include major faults or minor faults.

[00377] An example of a fault may comprise a fracture of and/or leak from a reactor vessel (e.g., a fracture in the reformers 1808-1810 or the heater 1809). The fracture and/or leak may be detected after a pressure sensor Pl -P10 measures a sudden drop in pressure of the reformate stream 1820 in the combustion heater 1809, or a sudden drop in pressure of the incoming HC stream 1804 (or the partially cracked reformate stream 1820) in the combustion- heated reformer 1808 or the electrically-heated reformer 1810. For example, the sudden drop in pressure may comprise a greater than 50% pressure drop (e.g., from 10 bara to less than or equal to 5 bara) within a predefined time. The predefined time may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90 minutes. In some cases, the predefined time may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90 minutes.

[00378] Another example of a fault may comprise a leakage of HC above predetermined leakage levels. The leakage of HC may be detected after an HC concentration sensor HCC1- HCC10 detects a concentration of HC greater than a threshold concentration (e.g., about 25 ppm) adjacent or near any component or fluid line of the HC reforming system 1800. In some instances, to detect the leakage, the HC concentration sensor HCC1-HCC10 may be positioned outside the wall(s) or container(s) of the component or fluid line of the HC reforming system 1800. [00379] An example of a fault may comprise a temperature offset (e.g., by a tolerance about 10% or more) from a target temperature range. For example, a target temperature range of the reformers 1808-1810 may comprise about 100 to about 600 °C, and a temperature sensor Tl- T11 may measure a temperature of less than about 90 °C or greater than about 660 °C, indicating a temperature offset fault. In some cases, the reformers 1808 and/or the reformer 1810 may be maintained at a target temperature range of at least about 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, or 800 °C, and at most about 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, or 900 °C. In some cases, the target temperature ranges between about 100 and 300, 150 and 350, 300 and 900, 350 and 800, 400 and 750, 450 and 700, 500 and 650, or 550 and 600 °C. In some cases, a target temperature range of the reformer 1808 and a target temperature range of the reformer 1810 may at least partially overlap.

[00380] In some cases, a temperature offset is defined by a selected tolerance of a target temperature (or a tolerance of a lower limit of a target temperature range, or an upper limit of a target temperature range). The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target temperature. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target temperature. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50% of the target temperature.

[00381] In another example, a fuel cell target temperature comprises about an ambient temperature to about 100 °C, about 100 °C to about 150 °C, or about 120 °C to about 200 °C. For example, based on the target fuel cell temperature being about 120 °C to about 200 °C, the temperature offset fault may be detected after a temperature sensor Tl-Tl l measures a fuel cell temperature of less than about 108 °C or greater than about 220 °C.

[00382] An example of a fault may comprise a pressure offset (e.g., by a tolerance about 10% or more) from a target pressure range. For example, a target pressure range in the reformers 1808-1810 may comprise about 1 to about 5 bar-absolute (bara), about 3 to about 8 bara, about 5 to about 10 bara, or about 10 to about 20 bara. For example, if the target pressure range in the reformer is about 10 to about 20 bara a pressure sensor Pl -P10 may measure a pressure of less than about 9 bara or greater than about 22 bara, indicating a pressure offset fault.

[00383] In some cases, a pressure offset is defined by a selected tolerance of a target pressure (or a tolerance of a lower limit of a target pressure range, or an upper limit of a target pressure range). The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target pressure. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target pressure. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50% of the target pressure. The target pressure (or target pressure range) may be a pressure (or a pressure range) at an outlet or inside of the HC storage tank 1802, an inlet, an outlet, or inside of the combustion-heated reformer 1808, an inlet, an outlet, or inside of the combustion heater 1809, an inlet, an outlet, or inside of the electrically heated reformer 1810, an inlet, an outlet, or inside of the heat exchanger 1806, an inlet, an outlet, or inside of the filter 1822, or an inlet, an outlet, or inside of the fuel cell 1824.

[00384] An example of a fault may comprise a concentration offset (e.g., by a tolerance about 10% or more) from a target concentration range (or a tolerance of a lower limit of a target concentration range, or an upper limit of a target concentration range). A target HC concentration range in the filtered reformate stream 1823 may comprise about 0.001 to about 0.01 ppm, about 0.01 to about 0.1 ppm, about 0.1 to about 1 ppm, about 0.1 ppm to about 100 ppm. For example, if the target HC concentration range is about 0.1 ppm to about 100 ppm, an HC concentration sensor HCC1-HCC10 may measure a concentration of greater than about 110 ppm, indicating a concentration offset fault.

[00385] In some cases, a concentration offset is defined by a selected tolerance of a target concentration. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target concentration. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target concentration. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50% of the target concentration.

[00386] After a fault is detected using the fault detection module 2214, in some instances, the controller 2200 may execute or perform a corrective action. For example, after a fault is detected, the controller may execute or perform a complete shutdown of the HC reforming system 1800 by stopping a flow rate of the incoming HC stream 1804, power provided the heaters 1809-1811, and/or the fuel cell 1824. In another example, after a fault is detected, the controller may execute or perform a partial shutdown of the HC reforming system 1800 by reducing power provided to the heater 1809-1811 and/or the fuel cell 1824.

[00387] In some cases, after a fault is detected by the fault detection module 2214, the combustion-heated reformer 1808 may operate in a hot-standby mode to maintain the temperature in the combustion-heated reformer 1808 within a target temperature range (the hot- standby mode is described in further detail with respect to FIG. 23L). In some cases, the hot standby mode (e.g., without the fuel cell outputting power) may be maintained until the shutdown process is executed. In some cases, the hot standby mode (e.g., without the fuel cell outputting power) may be maintained until fuel cell power output resumes.

Anode Off-gas and Cathode Off-gas as Reactants in Combustion Heater

[00388] FIG. 23A is a block diagram illustrating the utilization of an anode off-gas 2303 and a cathode off-gas 2304 directed from the fuel cell 1824 (for example, via one or more outlet ports in the fuel cell 1824) as reactants for combustion in the combustion heater 1809. The anode off-gas 2303 may be substantially similar or substantially identical to the off-gas 128 described with respect to FIGS. 18A-21B.

[00389] The fuel cell may receive an anode input 2301 (at least hydrogen, for example, in the reformate stream 1820) and a cathode input 2302 (at least oxygen, for example, in the air stream 1818), for example, via one or more inlet ports in the fuel cell.

[00390] Unconsumed hydrogen (e.g., that is not consumed by the fuel cell 1824) may be supplied as the anode off-gas 2303, and unconsumed oxygen (e.g., that is not consumed by the fuel cell 1824) may be supplied as a cathode off-gas 2304 (as reactants for the combustion reaction in the combustion heater 1809). In some cases, water may be removed from the anode off-gas 503 and/or the cathode off-gas 2304 before the anode off-gas 2303 and/or the cathode off-gas 2304 are provided to the combustion heater 2309 (e.g., using a condenser or a filter).

Combustion Exhaust to Regenerate Adsorbents

[00391] FIG. 23B is a block diagram illustrating the utilization of heat from the combustion exhaust 1814 (emitted by combustion heater 1809) to regenerate the filter 1822 (e.g., via temperature swing adsorption). The desorbed HC or CO2 2305 may be vented to the atmosphere, combusted in the combustion heater 1809, or mixed with water and discharged externally.

[00392] In some cases, the combustion exhaust stream 1814 is used to regenerate the filter 1822 by directly contacting the combustion exhaust stream 1814 with the filter 1822 (i.e., a direct purge of the filter material). In some cases, the combustion exhaust stream 1814 is used to regenerate the filter 1822 by transferring heat to the filter 1822 via a heat exchanger (and/or an intermediate fluid, such as a glycol and/or water).

Reduction of NOx in Combustion Exhaust

[00393] FIG. 23C is a block diagram illustrating the reduction of nitrogen oxides (NO _X , e.g., NO, NO2, N2O, etc.) in the combustion exhaust 1814 emitted by the combustion heater 1809. A selective catalytic reduction (SCR) catalyst 2306, such as platinum or palladium, may be used to convert NO _X into H2O and N2. A reductant such as anhydrous ammonia (NH3), aqueous ammonia (NH4OH), or urea (CO(NH2)2) solution may be added to the exhaust 1814 to react with NO _X . The purified exhaust 2307 may then be vented to the atmosphere. This removal of harmful NO _X emissions advantageously reduces harm to the environment and living organisms.

Anode Off-gas and Cathode Off-gas to Regenerate Adsorbents

[00394] FIG. 23D is a block diagram illustrating the utilization of the anode off-gas 2303 and/or the cathode off-gas 2304 to regenerate the filter 1822 (e.g., via temperature swing adsorption). The desorbed HC or CO2 2308 may be vented to the atmosphere, or mixed with water and discharged externally. In some cases, combustion of the hydrogen in the anode offgas 2303 may provide heat to regenerate the filter 1822. In some cases, lower temperature catalytic combustion of the hydrogen in the anode off-gas 2303 may provide heat to regenerate the filter 1822.

Oxidation of HC in Reformate Stream

[00395] FIG. 23E is a block diagram illustrating the oxidation of trace or residual HC in the reformate stream 1820 output by the combustion-heated reformer 1808 and/or the electrically-heated reformer 1810. A selective HC oxidation catalyst 2309 (e.g., comprising a transition metal) may be used to convert the trace or residual HC (e.g., a hydrocarbon) into CO2 and H2O. Air (including at least oxygen, e.g., the air stream 1818) may be provided to the catalyst 2309 to react with the trace or residual HC. The purified reformate stream 2310 may be provided to the fuel cell 1824 (to generate electricity) or to the combustion heater 1809 (to be combusted for self-heating the reformer 1808). The catalyst 2309, when combined with the filter 1822, may advantageously reduce the size (e.g., volume and weight) of the filter 1822, and may reduce the need to periodically replace cartridges in (or periodically regenerate) the filter 1822. In some cases, introducing air (including at least oxygen) may combust and remove at least part of the residual HC (by converting into CO2 and H2O) without the catalyst 2309.

Induction Heater

[00396] FIG. 23F is a block diagram illustrating the heating of the electrically-heated reformer 1810 using an induction heater 2311. The induction heater 2311 may comprise a magnetically-sensitive material in contact with the reforming catalyst in the electrically-heated reformer 1810, in addition to a magnetic device (e.g., an electrical coil or other magnet) that generates a magnetic field to heat the magnetically-sensitive material (e.g., via an electromagnetic interaction).

Heat Pump

[00397] FIG. 23G is a block diagram illustrating the utilization of a heat pump 2314 to transfer heat 2313 from a relatively cold component 2312 to a relatively hot component 2315. The heat pump 2314 may be driven by electricity (for example, vapor compression cycle), or driven by heat (for example, adsorption refrigeration), or a combination of both.

[00398] The components 2312 and 2314 may be any component of the HC reforming system 1800 described in the present disclosure. For example, the heat pump 2314 may transfer heat from the filter 1822 to the reformate stream 1820. Other examples include, but are not limited to, liquefying methane gas, condensing water from a cathode off-gas or combustion exhaust, removing heat from one or more heat exchangers, or removing heat from one or more fuel cells. In some cases, the refrigerants of the heat pump 2314 may comprise ammonia, methanol, water, or mixture of one or more of ammonia, methanol, or water.

Fluid Pump

[00399] FIG. 23H is a block diagram illustrating the utilization of a fluid pump 2316 to pressurize the incoming HC stream 1804 provided by the storage tank 1802. The storage tank 1802 and/or the pump 2316 may use the heat provided by one or more electrical heaters, the combustion-heated reformer 1808, the combustion heater 1809, and/or the electrically-heated reformer 1810 to pressurize or vaporize the incoming HC stream 1804. In some embodiments, the pump 2316 may be electrically powered and/or controlled.

Control of Pressure, Flow Rate, and Gas Velocity at Fuel Cell

[00400] FIG. 231 is a block diagram illustrating the utilization of flow control units 2317 to control the pressure, flow rate, and/or gas velocity of fluid streams in the HC reforming system 1800. The flow control units 2317 may be substantially similar or substantially identical to the flow control units FCU1-10 described with respect to FIG. 22G. The flow control units 2317 may comprise one or more pressure drop elements, one or more pumps, one or more check valves, one or more one-way valves, one or more three-way valves, one or more restrictive orifices, one or more valves, one or more flow regulators, one or more pressure regulators, one or more back pressure regulators, one or more pressure reducing regulators, one or more back flow regulators, one or more flow meters, one or more flow controllers, or any combination thereof. The flow control units 2317 may be controlled manually, automatically, or electronically.

[00401] For example, the fuel cell 1824 may draw the reformate stream 1820 at a pressure that is maintained within a selected tolerance (e.g., a tolerance of about 1%, about 5%, or about 10%) at the inlet of the fuel cell 1824. The target pressure may be at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, or 40 bar absolute (bara) at the inlet of the fuel cell 1824. The target pressure may be at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, or 40 bara at the inlet of the fuel cell 1824. In some cases, the target pressure may be between about 1 and 40, 2 and 35, 3 and 30, 4 and 25, 5 and 20, or 10 and 15 bara at the inlet of the fuel cell 1824. In some cases, the target pressure range is about 2 to about 5 bara at the inlet of the fuel cell 1824.

[00402] In some cases, the selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of a target pressure at the inlet of the fuel cell 1824. In some cases, the selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of a target pressure at the inlet of the fuel cell 1824. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50% of the target pressure at the inlet of the fuel cell 1824.

[00403] To maintain this pressure of the reformate stream 1820 at the inlet of the fuel cell 1824 (within the selected tolerance), the flow control units 2317 may be controlled to modulate the pressure of the HC stream 1804 (before the stream 1804 enters the reformers 1808-1810), or the flow control units 2317 may be controlled to modulate the pressure of the reformate stream 1820 (before the stream 1820 enters the fuel cell 1824). As the fuel cell 1824 consumes more of the reformate stream 1820 and increases output power, the pressure of the reformate stream 1820 may be measured at the fuel cell inlet (using a pressure sensor Pl -P10), and the flow control units 2317 may be modulated (e.g., based on the pressure measured by the pressure sensor Pl- Pl 0) to increase the flow rate of the HC stream 1804 or the reformate stream 1820 (to maintain the pressure of the reformate stream 1820 at the selected tolerance at the fuel cell inlet).

[00404] In some embodiments, one or more pressure regulators (e.g., the back pressure regulators BPR1 or BPR2, or the pressure reducing regulator PRR1 or PRR2, as described with respect to FIG. 22H) may be configured to maintain the pressure of the reformate stream 1820 at the inlet of the fuel cell 1824 within the selected tolerance.

[00405] In some embodiments, the fuel cell 1824 may draw the reformate stream 1820 at a flow rate that is maintained within a selected tolerance (e.g., a tolerance of about 1%, about 5%, or about 10%) at the inlet of the fuel cell 1824. In some cases, the selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of a target flow rate at the inlet of the fuel cell 124. In some cases, the selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of a target flow rate at the inlet of the fuel cell 1824. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50% of the target flow rate at the inlet of the fuel cell 1824.

[00406] To maintain this flow rate of the reformate stream 1820 at the inlet of the fuel cell 1824 (within the selected tolerance), a flow rate of the reformate stream 1820 may be measured at the fuel cell inlet (using a flow rate sensor FM1-FM11), and the flow control units 2317 may be controlled (based on the flow rate measured by the flow rate sensor FM1-FM11) to modulate the flow rate of the HC stream 1804 (before the stream 1804 enters the reformers 1808-1810), or the flow control units 2317 may be controlled (based on the flow rate measured by the flow rate sensor FM1-FM11) to modulate the flow rate of the reformate stream 120 (before the stream 1820 enters the fuel cell 1824).

[00407] In some embodiments, the flow control units 2317 may be configured to modulate a gas velocity of the reformate stream 1820 at the inlet of the fuel cell 1824. In some cases, the hydrogen and/or carbon dioxide in the reformate stream 1820 may purge liquid water in the fuel cell 1824 by directing the liquid water out of the fuel cell 1824. The gas velocity of the reformate stream 1820 may be modulated based on a concentration or volume of the liquid water in the fuel cell 1824 (which may be measured using, e.g., one or more humidity sensors in the fuel cell 1824 in communication with the controller 2200 described with respect to FIG. 22A). For example, in response to the measured concentration or volume of water in the fuel cell 1824 being greater than a threshold concentration or volume, the gas velocity of the reformate stream 1820 may be increased to facilitate the purging of water in the fuel cell 1824 (and vice versa).

[00408] In some embodiments, at least a portion of the reformate stream 1820 is recirculated in the fuel cell 1824, and the recirculated portion may be adjusted based on a concentration or volume of the liquid water in the fuel cell 1824, an H2 consumption rate of the fuel cell 1824, a CO2 concentration in the fuel cell 1824, humidity in the fuel cell 1824, the flow rate of the reformate stream 1820 at the inlet of the fuel cell 1824, or a power output of the fuel cell 1824.

Non-Linear Start-up Sequence

[00409] FIG. 23J is a block diagram illustrating a non-linear start-up sequence for the HC reforming system 1800. A first set of reformers 2320 may comprise a plurality of electrically- heated reformers (e.g., each one being substantially similar or substantially identical to the electrically-heated reformer 1810 described with respect to FIGS. 18A-21B). A second set of reformers 2321 and a third set of reformers 2322 may comprise a plurality of combustion-heated reformers (e.g., each one being substantially similar or substantially identical to the combustion- heated reformer 1808 described with respect to FIGS. 18A-21B). It is contemplated that the number of reformers in the second set 2321 may be greater than the number of reformers in the first set 2320, and likewise, it is contemplated that the number of reformers in the third set 2322 may be greater than the number of reformers in the second set 2321. In this way, a progressively larger number of reformers may be heated at each step of the non-linear startup sequence. For example, the first set of reformers 2320 may comprise two reformers, the second set of reformers 2321 may comprise four reformers, the third set of reformers 2322 may comprise eight reformers, and so on.

[00410] The non-linear start-up sequence may be performed by decomposing HC (e.g., the HC stream 1804) using the first set of reformers 2320 to generate a first reformate stream (e.g., the reformate stream 1820). Subsequently, the reformate stream produced by the first set of reformers 2320 may be combusted to heat the second set of reformers 2321 to generate a second reformate stream. Subsequently, the second reformate stream produced by the second set of reformers 2321 may be combusted to heat the third set of reformers 2322 to generate a third reformate stream.

[00411] It is noted that the presently described non-linear start-up sequence may involve any number of sets of reformers (e.g., at least two sets of reformers), and each set of reformers may comprise any number of reformers (e.g., at least one reformer). It is also noted that the nonlinear startup sequence may be initiated using the controller 2200 (for example, by initiating the heating of the electrically-heated reformers of the first set of reformers 2320).

Purging

[00412] FIG. 23K is a block diagram illustrating purging of the HC reforming system 1800. A purging gas 2323 may purge the HC reforming system 1800 of residual gases (for example, before starting the HC reforming system 1800 or after shutting down the HC reforming system 1800). The purging gas 2323 may direct residual HC in the HC reforming system 1800 (for example, residual HC in the reformers 1808-1810) into water or a scrubber.

[00413] The purging gas 2323 may comprise an inert or noble gas (for example, nitrogen, carbon dioxide, or argon). In some cases, the purging gas 2323 comprises hydrogen and may be flared or vented into the atmosphere. The purging gas 2323 may be stored in a dedicated tank, or may be generated by reforming HC. The purging of the HC reforming system may be initiated using the controller 2200 (for example, by modulating a valve to direct the purging gas 2323 into the reformers 1808-1810).

Hot Standby Mode

[00414] FIG. 23L is a block diagram illustrating the initiation of a hot standby mode for the HC reforming system 1800. The hot standby mode may advantageously reduce the time required to return to an operation mode, for example, by avoiding a shut down (or reduction in temperature) of the combustion reformer 1808 and/or the combustion heater 1809. Additionally, the hot standby mode may advantageously enable the system 1800 to adjust and respond to power demand at the fuel cell and/or hydrogen demand at a hydrogen processing module. Additionally, the hot standby mode may advantageously enable the maintenance of the fuel cell and/or the hydrogen processing module (e.g., due to a fault at the fuel cell and/or the hydrogen processing module) without shutting down (or reducing the temperature of) the combustion reformer 1808 and/or the combustion heater 1809. In some cases, the hot standby mode enables the system 1800 to operate for stationary or mobile hydrogen and/or power generation applications.

[00415] In an operation mode of the HC reforming system 1800, a flow control unit 2324 may direct the reformate stream 1820 (e.g., as an H2 processing flow 1819) to an H2 processing module 2335. The H2 processing module 2335 may be configured to generate electrical power and/or to supply H2 to various chemical or industrial processes, including, but not limited to, steel or iron processing, combustion engines, combustion turbines, hydrogen storage, hydrogen for chemical processes, hydrogen fueling stations, and the like. The H2 processing module 2335 may comprise one or more fuel cells 1824, one or more PSAs 1827, one or more flow distributors 1815, or one or more membrane hydrogen separation devices 1827 (described with respect to FIGS. 18A-21B and FIG. 23S). A leftover reformate stream 2336 (e.g., unconsumed H2 from fuel cell 1824, or H2 that is not supplied to chemical or industrial processes) may then be supplied to the combustion heater 1809 as a reactant for the combustion reaction. The leftover reformate stream 2336 may comprise the filtered reformate stream 1823, the anode offgas 1828, the anode off-gas 2303, the PSA exhaust stream 1828b, the hydrogen separation device retentate stream 2332, or the portion 1828c of the reformate stream 1820 distributed by the flow distributor 1815.

[00416] In some instances, the flow control unit 2324 may configured to monitor and/or modulate one or more flow rates and/or one or more pressures. In some instances, the flow control unit 2324 may comprise one or more pressure drop elements configured to reduce pressure, one or more pumps, one or more valves, one or more check valves, one or more oneway valves, one or more three-way valves, one or more restrictive orifices, one or more flow regulators, one or more pressure regulators, one or more back pressure regulators, one or more pressure reducing regulators, one or more back flow regulators, one or more flow meters, one or more flow controllers, or any combination thereof. In some instances, the flow control unit 2324 may be controlled manually, automatically, or electronically.

[00417] After initiating the hot standby operation, the power output by the one or more fuel cells 1824, or the supply of H2 to the various chemical or industrial processes, may be reduced or shut off entirely (by modulating the flow control unit 2324 to direct at least part of the reformate stream 1820 to the combustion heater 1809 for combustion in the combustion heater 1809), thereby maintaining the combustion-heated reformer 1808 in a target temperature range. Excess hydrogen may be vented or flared after passing the combustion heater 1809 (due to fuelrich conditions in the combustion-heater 1809).

[00418] The hot standby mode may be terminated by modulating the flow control unit 2324 to redirect the reformate stream 1820 to the H2 processing module 2335 (e.g., by increasing a flow rate or pressure of the H2 processing inlet flow 1819, for example, at an inlet of the fuel cell 1824), thereby starting or increasing the power output by and/or the H2 supplied to the H2 processing module 2335.

[00419] The hot standby mode may advantageously maintain the target temperature range in the combustion-heated reformer 1808 even while the H2 processing module 2335 reduces or shuts off the electrical power output or the supply of H2 to the chemical or industrial processes (in other words, turning off the combustion-heated reformer 1808 may be avoided). Therefore, during a fault situation (e.g., a fault associated with the fuel cell 1824), completely shutting down the HC reforming system 1800 may be prevented, and the time required to start-up the HC reforming system 1800 (and increase power output by the H2 processing module 2335, and/or increase the H2 supplied to the H2 processing module 2335) may be reduced.

[00420] In some instances, the flow rate of the incoming HC stream 1804 may (or may not be) configured to be the same during the operation mode and hot standby mode. In some instances, the flow rate of the incoming HC stream 1804 during the hot standby mode may be configured to be within a selected tolerance of the flow rate of the incoming HC stream 1804 during the operation mode. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance is about 5 to about 20%.

[00421] In some instances, the hot standby mode may be maintained without substantially reducing or increasing the flow rate of the incoming HC stream 1804 (or the flow rate of the reformate stream 1820). In some instances, during the hot standby mode, the flow rate of the incoming HC stream 1804 (or the flow rate of the reformate stream 1820) may be maintained within a selected tolerance of a target flow rate. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance may be about 5 to about 20%.

[00422] In some cases, during the hot standby mode, combustion characteristics in the combustion heater 1809 may be fuel-rich, and flare may be observed in the combustion exhaust 1814. In some cases, the hot standby mode is maintained by modulating a flow rate of the air stream 1818 (e.g., using the air supply unit 1816), so that the amount of H2 combusted in the combustion heater 1809 is modulated or controlled (which may prevent the excessive H2 combustion and overheating of the combustion heater 1809 and/or combustion-heated reformer 1808).

[00423] FIG. 23M is a plot illustrating a system pressure (e.g., pressure in the incoming HC stream 1804, reformate stream 1820, reformer 1808-1810, heat exchanger 1806, or HC filter 1822) over time during the startup mode, during the operation mode, and during the hot-standby mode for the HC reforming system 1800. The system pressure (e.g., pressure in the incoming HC stream 1804, reformate stream 1820, reformer 1808-1810, heat exchanger 1806, or filter 1822) during the hot standby mode may be higher than the system pressure during the operation mode. The system pressure may be measured, for example, using at least one of the pressure sensors Pl -P10.

[00424] In some embodiments, the flow control unit 2324 may configured to initiate the hot standby mode by increasing the system pressure. The flow control unit 2324 may initiate the flow of the reformate stream 1820 to the combustion heater 1809 when the pressure of the reformate stream 1820 (before reaching the flow control unit 2324) is equal to or greater than a threshold pressure.

[00425] In one example, if the H2 processing inlet flow 1819 is at least partially blocked or closed (while maintaining the flow rate of the incoming HC stream 1804 within a selected tolerance), the system pressure may increase. The flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of about 5 to about 20%.

[00426] If the pressure of the reformate stream 1820 before the flow control unit 2324 is equal to or greater than the threshold pressure (within a selected tolerance), the flow control unit 2324 may direct a portion or all of the reformate stream 1820 to the combustion heater 1809 (thereby transitioning to the hot standby mode). The selected tolerance of the threshold pressure may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance of the threshold pressure may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance of the threshold pressure may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance is about 5 to about 20%.

[00427] In some embodiments, the hot standby mode may be terminated, and the operation mode may be initiated by reducing the system pressure (e.g., pressure in the incoming HC stream 1804, reformate stream 1820, reformer 1808-1810, heat exchanger 1806, or filter 1822).

[00428] In one example, the system pressure may be reduced by increasing or initiating the H2 processing inlet flow 1819 to the H2 processing module 2335 (while maintaining the flow rate of the incoming HC stream 1804 within a selected tolerance). The flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the flow rate of the incoming HC stream 1804 may be maintained within a selected tolerance of about 5 to about 20%.

[00429] If the pressure of the reformate stream 1820 before the flow control unit 2324 is equal to or less than the threshold pressure (within a selected tolerance), the flow control unit 2324 may redirect a portion or all of the reformate stream 1820 supplied to the combustion heater 1809 back to the H2 processing module 2335. The selected tolerance of the threshold pressure may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance of the threshold pressure may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance of the threshold pressure may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance of the threshold pressure is about 5 to about 20%.

[00430] In some cases, the leftover reformate stream 2336 may be supplied to the combustion heater 1809 (to transition to the operation mode).

[00431] In some embodiments, the flow rate of the incoming HC stream 1804 may increase while transitioning from the hot standby mode to the operation mode. In some embodiments, the flow rate of the incoming HC stream 1804 may increase after transitioning from the hot standby mode to the operation mode (to increase the electrical power output by the H2 processing module 2335, and/or to supply more H2 to the industrial or chemical processes of the H2 processing module 2335).

[00432] In some embodiments, the HC reforming system 1800 comprises two or more HC reformers 1808-1810, and the hot standby mode may be initiated using at least one HC reformer 1808-1810, and the remaining HC reformers 1808-1810 may be maintained in the operation mode.

[00433] In some embodiments, combustion of the reformate stream 1820 maintains a temperature in the combustion-heated reformer 1808 within a target temperature range (for example, during the hot standby mode).

[00434] In some embodiments, the reformate stream 1820 is directed to the combustion heater 1809 in thermal communication with the combustion-heated reformer 1808, so that the combustion heater 1809 receives substantially all of the reformate stream 1820.

[00435] In some embodiments, an amount (e.g., flow rate) of the HC stream 1804 directed to the combustion-heated reformer 1808 is controlled so that a first portion of the reformate stream 1820 (combusted in the combustion heater 1809) includes substantially all of the reformate stream 1820 (for example, during the hot standby mode).

[00436] In some embodiments, an amount (e.g., flow rate) of a second portion of the reformate stream 1820 (e.g., the H2 processing flow 1819 that is processed in the hydrogen processing module 2335) is increased (e.g., when transitioning from the hot standby mode to the operation mode).

[00437] In some embodiments, the amount (e.g., flow rate) of the HC stream 1804 directed to the combustion-heated reformer 1808 may be increased to a first target HC flow rate range (for example, during the hot standby mode). [00438] In some embodiments, a second portion of the reformate stream 1820 is vented or flared (for example, during the hot standby mode). In some cases, at least about 30, 40, 50, 60, 70, 80, or 90% of the reformate stream 120 may be vented or flared out of the combustion heater 1809 during the hot standby mode. In some cases, at most about 30, 40, 50, 60, 70, 80, or 90% of the reformate stream 1820 may be vented or flared out of the combustion heater 1809 during the hot standby mode. In some cases, of from about 30 to about 60%, of from about 40 to about 70%, of from about 50 to about 80%, or of from about 60 to about 90% of the reformate stream 1820 is vented or flared out of the combustion heater 1809 during the hot standby mode.

Startup Mode

[00439] As shown in FIG. 23M, the system pressure (e.g., pressure in the incoming HC stream 1804, reformate stream 1820, reformer 1808-1810, heat exchanger 1806, or filter 1822) during the startup mode and hot standby mode may be higher than the system pressure during the operation mode. In some cases, the system pressure during the startup mode may be the same as (or different from) the system pressure during the hot standby mode. In some cases, the system pressure during the startup mode and hot standby mode may be higher than the system pressure during the operation mode. In some cases, the system pressure during the startup mode may be the same as the system pressure during the hot standby mode within a selected tolerance. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance is about 5% to about 20%.

[00440] In some cases, the startup mode may comprise a system configuration similar or at least partially identical to the hot standby mode described with respect to FIG. 23L, for example, a portion or all of the reformate stream 1820 may be supplied to the combustion heater 109 using one or more flow control units (e.g., flow control unit 2324). In some cases, the startup mode may be transitioned to the operation mode by reducing the system pressure (e.g., pressure in the incoming HC stream 1804, reformate stream 1820, reformer 1808-1810, heat exchanger 1806, or filter 1822). In some cases, the system pressure may be reduced by increasing or initiating the H2 processing inlet flow 1819 to the H2 processing module 2335 using one or more flow control units (e.g., flow control unit 2324). In some cases, the system pressure may be reduced by increasing or initiating the H2 processing inlet flow 1819 to the H2 processing module 2335 using one or more flow control units while maintaining the flow rate of the incoming HC stream 1804 within a selected tolerance. In some cases, the leftover reformate stream 2336 may be supplied to the combustion heater 1809 to transition to the operation mode using one or more flow control units. In some cases, the flow control unit 2324 may be used to transition the startup mode to the operation mode by directing the H2 processing inlet flow 1819 to the H2 processing module 2335. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and about 90%. In some instances, the selected tolerance is about 5% to about 20%.

[00441] In some instances, the flow rate of the incoming HC stream 1804 may be (or may not be) configured to be the same during the startup mode and the operation mode. In some instances, the flow rate of the incoming HC stream 1804 during the startup mode may be configured to be within a selected tolerance of the flow rate of the incoming HC stream 1804 during the operation mode. The selected tolerance may be at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. The selected tolerance may be at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, or 90%. In some cases, the selected tolerance may be between about 1 and 90, 5 and 80, 10 and 70, 20 and 60, 30 and 50, or 40 and 90%. In some instances, the selected tolerance is about 5% to about 20%.

[00442] In some embodiments, the flow rate of the incoming HC stream 1804 may increase while transitioning from the startup mode to the operation mode. In some embodiments, the flow rate of the incoming HC stream 1804 may increase after transitioning from the startup mode to the operation mode to produce higher electrical power from and/or to supply more H2 to the industrial or chemical processes in the H2 processing module 2335.

[00443] In some embodiments, a pressure of the reformate stream 1820 is reduced when the reformate stream 1820 is directed through the hydrogen processing module 2335 (e.g., during the operation mode) compared to when the reformate stream is not directed through the hydrogen processing module 2335 (e.g., during the startup mode or the hot standby mode).

[00444] In some embodiments, when a threshold amount of the reformate stream 1820 is directed to the hydrogen processing module 2335, substantially all of the reformate stream 1820 passes through the hydrogen processing module 2335 (e.g., during the operation mode).

[00445] In some embodiments, an amount (e.g., flow rate) of the HC stream 1804 directed to the combustion-heated reformer 1808 is increased over a time period (beginning when the combustion-heated reformer 1808 is heated to a target temperature range).

[00446] In some embodiments, the amount of the HC stream 1804 directed to the combustion-heated reformer 1808 is increased to a first target HC flow rate range. In some embodiments, the reformate stream 1820 is directed to a hydrogen processing module 2335 when the first target HC flow rate range is reached. In some embodiments, the flow rate of the HC stream 1804 is subsequently increased to a second target HC flow rate.

[00447] In some embodiments, a first portion of the reformate stream 1820 is combusted with oxygen, and the oxygen is provided in a substantially constant proportion relative to the hydrogen in the first portion of the reformate steam 1820. In some cases, the substantially constant proportion may comprise a constant mass ratio within a selected tolerance (e.g., mass of hydrogen to mass of oxygen), a constant volume ratio within a selected tolerance (e.g., volume of hydrogen to volume of oxygen), or a constant molar ratio within a selected tolerance (e.g., moles of hydrogen to moles of oxygen). In some cases, the selected tolerance may comprise at most about 1, 5, 10, 20, 30, 40, or 50% of a target proportion. In some cases, the selected tolerance may comprise of from about 1 to 10%, of from about 5 to 10%, or of from about 5 to 15% of a target proportion.

Control of Temperature in Combustion-Heated Reformer

[00448] FIG. 23N is a block diagram illustrating the control of temperature inside the combustion-heated reformer 1808 and/or the combustion heater 1809. The combustion-heated reformer 1808 and/or the combustion heater 1809 may be maintained at a target temperature range, for example, of from about 300 °C to about 700 °C. In some instances, the combustion- heated reformer 1808 and/or the combustion heater 1809 may be maintained at a target temperature range of from about 400 °C to about 600 °C. In some instances, the combustion- heated reformer 108 and/or the combustion heater 109 may be maintained at a target temperature range of at least about 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, or 800 °C, and at most about 400, 450, 500, 550, 600, 650, 700, 750, 800, or 900 °C. In some cases, the target temperature ranges between about 300 and 900, 350 and 800, 400 and 750, 450 and 700, 500 and 650, or 550 and 600 °C. It is noted that the electrically-heated reformer 1810 and/or the electrical heater 1811 may be maintained at the same target temperature range (or a different target temperature range) as the combustion-heated reformer 1808 and/or the combustion heater 1809.

[00449] In response to the temperature of the combustion-heated reformer 1809 being outside or deviating from the target temperature range (in other words, being less than the lower limit of the temperature range, or being greater than the upper limit of the temperature range), the flow rate and/or pressure of the HC stream 1804, the air stream 1818 (e.g., comprising oxygen), the reformate stream 1820, and/or the anode off-gas 1828 may be modulated (e.g., using flow control units 2317 and/or the flow control units FCU1-FCU10) to maintain the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809 within the temperature range.

[00450] For example, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the HC stream 1804 may be increased (thereby providing more reactant for the endothermic HC reforming reaction which absorbs heat). In some embodiments, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the air stream 1818 may be decreased (thereby providing less oxygen for the combustion reaction). In some embodiments, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the reformate stream 1820 may be decreased (thereby providing less hydrogen for the combustion reaction). In some embodiments, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the anode off-gas 1828 may be decreased (thereby providing less hydrogen for the combustion reaction).

[00451] For example, to increase the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the HC stream 1804 may be decreased (thereby providing less reactant for the endothermic HC reforming reaction, which absorbs heat). In some embodiments, to increase the temperature the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the air stream 1818 may be increased (thereby providing more oxygen and more combustion of H2 for the combustion reaction).

[00452] In some embodiments, to increase the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the reformate stream 1820 may be increased (thereby generating more hydrogen from the HC reforming process and providing more hydrogen for the combustion reaction). In some embodiments, to increase the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the anode off-gas 1828 may be increased (thereby providing more hydrogen for the combustion reaction).

[00453] In some cases, to increase the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the hydrogen consumption rate from the fuel cell 1824 may be reduced (thereby providing more hydrogen to the anode off-gas 1828 and to the combustion heater 1809 for the combustion reaction). In some cases, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the hydrogen consumption rate from the fuel cell 1824 may be increased (thereby providing less hydrogen to the anode off-gas 1828 and to the combustion heater 1809 for the combustion reaction).

[00454] In some instances, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the air stream 1818 may be increased (thereby providing a fuel-lean or air-rich condition, where N2 absorbs at least part of the combustion heat and lowers the flame or combustion temperature at the combustion heater 1809).

[00455] In some instances, to decrease the temperature of the combustion-heated reformer 1808 and/or the combustion heater 1809, the flow rate and/or pressure of the air stream 1818 may be increased (thereby providing a fuel-lean or air-rich condition, where N2 absorbs at least part of the combustion heat and lowers the flame or combustion temperature at the combustion heater 1809). In some cases, the fuel -lean or air-rich condition is maintained during at least about 10, 20, 30, 40, 50, 60, 70, 80, or 90% of the operational time of the operation mode. In some cases, the fuel-lean or air-rich condition is maintained during at most about 10, 20, 30, 40, 50, 60, 70, 80, or 90% of the operational time of the operation mode. In some cases, the fuellean or air-rich condition is maintained of from about 30 to about 50%, of from about 40 to about 60%, of from about 50 to about 70%, of from about 60 to about 80%, or of from about 70 to about 90% of the operational time of the operation mode.

Dynamic Control

[00456] The systems and methods described herein can be dynamically controlled to achieve certain objectives. For example, an amount of HC that is reformed can be adjusted in response to a variable need for hydrogen. In a maritime deployment, for example, at a constant speed, a ship moving into a head-wind can require more hydrogen (e.g., to generate more power from fuel cell(s)) compared to a ship moving with the wind.

[00457] In some embodiments, a dynamic control method may comprise directing the HC stream to a reformer at an HC flow rate to produce a reformate stream comprising hydrogen. The method can further comprise combusting a first portion of the reformate stream with oxygen to heat the reformer. A second portion of the reformate stream can be processed in a hydrogen processing module (e.g., in a fuel cell). One or more adjustments can be made based at least in part on a stimulus (e.g., the stimulus can be a user input or an automated input based on a measurement). For example, the adjustment(s) can include changing the HC flow rate (i.e., increasing or decreasing an amount of HC reformed). The adjustment(s) can also include changing a percentage of the reformate stream that is the first portion of the reformate stream (i.e., increasing or decreasing the percentage combusted to heat the reformer). The adjustment s) can also include changing a percentage of the reformate stream that is the second portion of the reformate stream (i.e., increasing or decreasing the percentage that is sent to the hydrogen processing module). The adjustment s) can also include changing a percentage of the reformate stream that is vented or flared (e.g., increasing or decreasing the percentage that is vented or flared at a combustion exhaust of the combustion heater).

[00458] In some cases, at least two of the adjustments are performed. In some cases, at least three of the adjustments are performed. In some cases, all of the adjustments are performed. In some cases, the dynamic control method further comprises changing an oxygen flow rate (i.e., increasing or decreasing the oxygen flow rate) used for combustion to heat the reformer.

[00459] In some cases, the stimulus comprises a change in an amount of the hydrogen used by the hydrogen processing module (i.e., an increase or a decrease in an amount of hydrogen used by the hydrogen processing module). In some cases, the stimulus comprises a temperature of the reformer being outside of a target temperature range. In some cases, the stimulus comprises a change in an amount or concentration of HC in the reformate stream (i.e., an increase or a decrease in an amount of concentration of HC in the reformate stream).

[00460] In some cases, to decrease the amount or concentration of HC in the reformate stream 1820, the temperature of the combustion heater 1809 and/or the reformers 1808 and/or 1810 may be increased (to increase HC conversion efficiency). In some cases, to increase the amount or concentration of HC in the reformate stream 1820, the temperature of the combustion heater 1809 and/or the reformers (1809 and/or 1810) may be decreased (to lower the HC conversion efficiency).

[00461] In some cases, the HC conversion efficiency is maintained to be at least about 80, 85, 90, 95, 99, or 99.5%. In some cases, the HC conversion efficiency is maintained to be at most about 80, 85, 90, 95, 99, or 99.5%. In some cases, the HC conversion efficiency is maintained to be of from about 80 to about 90%, of from about 85 to about 90%, of from about 90 to about 95%, of from about 95 to about 99%, or of from about 95 to about 99.9%.

[00462] In some cases, the amount or concentration of HC in the reformate stream 1820 is maintained to be at least about 100, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000, 30000, 40000, or 50000 ppm. In some cases, the amount or concentration of HC in the reformate stream 1820 is maintained to be at most about 100, 500, 1000, 2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 20000, 30000, 40000, or 50000 ppm. In some cases, a target amount or concentration of HC in the reformate stream 1820 is of from about 500 to about 2500 ppm, of from about 1000 to about 3000 ppm, of from about 2000 to about 4000 ppm, of from about 3000 to about 5000 ppm, of from about 4000 to about 6000 ppm, of from about 5000 to about 7000 ppm, of from about 6000 to about 8000 ppm, of from about 7000 to about 9000 ppm, of from about 8000 to about 10000 ppm, of from about 5000 to about 15000 ppm, or of from about 5000 to about 20000 ppm. In some cases, the filter 1822 is used to filter the residual or trace HC in the reformate stream 120 and produce a filtered reformate stream 1823.

[00463] In some cases, the amount of HC reformed, the amount of reformate directed to the hydrogen processing unit, the amount of reformate directed to the combustion heater to heat the reformer, and/or the amount of reformate that is vented or flared can be changed so that: a temperature of the reformer is within a target temperature range; and/or at most about 10% of the reformate stream is vented or flared.

[00464] In some cases, the adjustment(s) are performed or achieved for at least 95% of an operational time period (e.g., of the HC reforming system 1800). An operational time period may begin when initiating the heating of a start-up reformer (such as electrically-heated reformer 1810), when initiating the flow of the HC stream 1804 from the storage tank 1802, or when initiating the flow of the reformate stream 1820 to a hydrogen processing module, and may end after the reformer 1808-1810, the heaters 1809-1811, and/or fuel cell 1824 are shut down. In some cases, the operational time period is at least about 8 consecutive hours. In some cases, the operational time period is at least about 4, 8, 12, 16, 20, 24, 28, or 32 consecutive hours. In some cases, the operational time period is at most about 4, 8, 12, 16, 20, 24, 28, or 32 consecutive hours.

[00465] Any suitable amount of the reformate stream can be vented or flared. In some cases, the amount of HC reformed to produce the reformate stream is in excess of an amount of HC reformed that is used by the hydrogen processing module(s) and used to heat the reformer(s). This excess amount can represent a waste of HC fuel when reformate is vented or flared. However, operating without excess HC reformation results in a lack of a buffer for the reformate required for processing in the hydrogen processing module(s) and heating the reformer(s). In some cases, about 20%, 15%, 10%, 5%, 3%, or 1% of the reformate stream is vented or flared. In some cases, less than about 20%, 15%, 10%, 5%, 3%, or 1% of the reformate stream is vented or flared.

[00466] In some cases, the vented reformate may be stored in a tank (e.g., to store buffer hydrogen) for later use. In some cases, the vented reformate stored in the tank may be combusted to heat one or more reformers or may be provided to a hydrogen processing module. [00467] The systems and methods described herein can be efficiently and reliably operated. Efficient and reliable operation can include meeting an efficiency target for a suitably long period of time or suitably large fraction of a time period. For example, the adjustment s) may be performed or achieved for at least about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% of an operational time period. In some cases, the adjustment(s) may be performed or achieved for at most about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100% of an operational time period. In some cases, the operational time period is at least about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100, 500, 1000, or 2000 hours. In some cases, the operational time period is at most about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 50, 100, 500, 1000, or 2000 hours.

[00468] In some cases, the stimulus is based at least in part on an increase in an amount of the hydrogen used by the hydrogen processing module. In some cases, the increase in an amount of hydrogen is a projected increase in an amount of hydrogen used (in other words, a predicted increase in demand of hydrogen used by the hydrogen processing module at a subsequent time) or a target increase in an amount of hydrogen used. In some cases, based on the increase in an amount of hydrogen used by the hydrogen processing module, one or more of (i) the HC flow rate is increased, (ii) the percentage of the reformate stream that is the first portion of the reformate stream is decreased, (iii) the percentage of the reformate stream that is the second portion of the reformate stream is increased, or (iv) the percentage of the reformate stream that is vented or flared is decreased.

[00469] In some cases, the stimulus is based at least in part on a decrease in an amount of the hydrogen used by the hydrogen processing module. In some cases, the decrease in an amount of hydrogen used is a projected decrease in an amount of hydrogen (in other words, a predicted decrease in demand of hydrogen used by the hydrogen processing module at a subsequent time) or a target decrease in an amount of hydrogen. In some cases, based on the decrease in an amount of hydrogen used by the hydrogen processing module, one or more of: (i) the HC flow rate is decreased, (ii) the percentage of the reformate stream that is the first portion of the reformate stream is increased, (iii) the percentage of the reformate stream that is the second portion of the reformate stream is decreased, or (iv) the percentage of the reformate stream that is vented or flared is increased.

[00470] In some cases, the stimulus comprises (a) a discontinued processing of hydrogen using the hydrogen processing module or (b) a fault or malfunction of the hydrogen processing module. [00471] In some cases, a plurality of hydrogen processing modules each comprise the hydrogen processing module, and the stimulus comprises at least one of (a) a discontinued processing of the hydrogen using one of the plurality of hydrogen processing modules and/or (b) a fault or malfunction in one of the plurality of hydrogen processing modules.

[00472] In some cases, the percentage of the reformate stream that is the second portion of the reformate stream (processed by the hydrogen processing module) is changed to about zero percent in response to the stimulus.

[00473] In some cases, substantially none of the reformate stream is directed to the hydrogen processing module in response to the stimulus.

[00474] In some cases, substantially all of the reformate stream is directed to at least one of the combustion-heated reformer and/or a combustion heater in thermal communication with the combustion-heated reformer in response to the stimulus.

[00475] In some cases, a portion of the reformate stream is vented or flared in response to the stimulus.

[00476] In some cases, the stimulus is detected using a sensor. In some cases, the stimulus is communicated to a controller. In some cases, the adjustment(s) are performed with the aid of a programmable computer or controller. In some cases, the adjustment(s) are performed using a flow control unit.

[00477] In some cases, the stimulus is a pressure. In some cases, the pressure is increased in response to decreasing a flow rate to the hydrogen processing module. In some cases, the pressure is a pressure of the reformate stream.

Proportional Integral Derivative (PID) Control

[00478] In some embodiments, the temperature inside the combustion-heated reformer 108 and/or the combustion heater 1809 may be controlled using PID control, which entails a control loop mechanism employing feedback. A PID controller may automatically apply an accurate and responsive correction to a control function. The PID controller (e.g., controller 2200) in conjunction with one or more sensors (e.g., temperature sensors T1-T10) may be employed to perform the PID control.

[00479] In some embodiments, the temperature inside the combustion-heated reformer 1808 and/or the combustion heater 1809 may be controlled using Proportional (P), Proportional Integral (PI), or Proportional Derivative (PD) control, which entails a control loop mechanism employing feedback. A P, PI, or PD controller may automatically apply an accurate and responsive correction to a control function. The P, PI, or PD controller (e.g., controller 2200) in conjunction with one or more sensors (e.g., temperature sensors T1-T10 and/or time sensors) may be employed to perform the control.

[00480] The PID controller may continuously calculate an error value (e(t)) as the difference between a desired setpoint (SP) and a measured process variable (PV), and may apply a correction based on proportional, integral, and derivative terms (denoted P, I, and D respectively). The P, PI, or PD controller may apply a correction based on one or two of proportional, integral, and derivative terms (denoted P, I, and D respectively), accordingly.

[00481] In one example, proportional control may be performed by (a) calculating a temperature difference between a temperature measured in the combustion-heated reformer 1808 or the combustion heater 1809 and a set-point temperature within a target temperature range, and (b) (i) changing the HC flow rate (e.g., the flow rate of the HC stream 1804) by an amount that is based at least in part on the temperature difference, (ii) changing the oxygen flow rate (e.g., the flow rate of the air stream 1818) by an amount that is based at least in part on the temperature difference, (iii) changing a percentage of the reformate stream 1820 that is processed by the H2 processing module 2335 by an amount that is based at least in part on the temperature difference, (iv) changing a percentage of the reformate stream 1820 that is combusted in the combustion heater by an amount that is based at least in part on the temperature difference, or (v) changing a percentage of the reformate stream 1820 that is vented or flared out of the combustion heater by an amount that is based at least in part on the temperature difference.

[00482] For example, the HC flow rate, the oxygen flow rate, the percentage of the reformate stream that is processed by the H2 processing module, the percentage of the reformate stream that is combusted in the combustion heater, and/or the percentage of the reformate stream that is vented or flared out of the combustion heater may be changed by a proportional factor that is proportional to the temperature difference. The value of the proportional factor may be greater when the temperature difference is greater. For example, for a set point temperature of 450 °C, the proportional factor may be greater for a measured temperature of 350 °C (a temperature difference of 100 °C) compared to a measured temperature of 400 °C (a temperature difference of 50 °C).

[00483] In some embodiments, the proportional factor is different for each of changing the HC flow rate, the oxygen flow rate, the percentage of the reformate stream that is processed by the H2 processing module, the percentage of the reformate stream that is combusted in the combustion heater, and/or the percentage of the reformate stream that is vented or flared out of the combustion heater. [00484] In some embodiments, calculating the temperature difference may be repeated at a subsequent time point to obtain a subsequent temperature difference, and changing the HC flow rate, the oxygen flow rate, the percentage of the reformate stream that is processed by the H2 processing module, the percentage of the reformate stream that is combusted in the combustion heater, and/or the percentage of the reformate stream that is vented or flared out of the combustion heater may be repeated to further change the HC flow rate, the oxygen flow rate, the percentage of the reformate stream that is processed by the H2 processing module, the percentage of the reformate stream that is combusted in the combustion heater, and/or the percentage of the reformate stream that is vented or flared out of the combustion heater (by an amount that is proportional to the subsequent temperature difference). The aforementioned steps may be repeated until the measured temperature is within the target temperature range.

[00485] In some embodiments, integral control may be performed. For example, the temperature measured in the reformer 1808 or combustion heater 1809 may be a first temperature that is measured at a first time point, and the integral control may be performed by (a) measuring a second temperature of the reformer 1808 or the combustion heater 1809 at second time point subsequent to the first time point, (b) calculating a time period between the first time point and the second time point, (c) calculating a temperature difference between first temperature and the second temperature, and (d) changing one or more of the HC flow rate, the oxygen flow rate, the percentage of the reformate stream that is processed by the H2 processing module, the percentage of the reformate stream that is combusted in the combustion heater, and/or the percentage of the reformate stream that is vented or flared out of the combustion heater (by an amount that is based at least in part on the time period and the temperature difference). In some embodiments, the aforementioned steps are repeated until the measured temperature is within the target temperature range.

Flaring or Venting Hydrogen in Combustion Heater Exhaust

[00486] FIG. 230 is a block diagram illustrating the flaring or venting 2325 of hydrogen in the combustion exhaust 1814 of the combustion heater 1809 to depressurize the reformers 1808-1810.

[00487] In some embodiments, the hydrogen may be flared in the combustion exhaust 1814 of the combustion heater 1809 by modulating a stochiometric ratio of (1) the hydrogen in the reformate stream 1820 supplied to the combustion heater 1809 to (2) the oxygen in the air stream 1818 supplied to the combustion heater 1809. Modulating the stochiometric ratio may comprise modulating the flow rate and/or pressure of the air stream 1818 supplied to the combustion heater 1809 to maintain a fuel rich condition of the combustion reaction (in other words, the hydrogen may be in stoichiometric excess). In some cases, modulating the stoichiometric ratio may comprise modulating the flow rate and/or pressure of the reformate stream 1820 supplied to the combustion heater 1809 to maintain the fuel rich condition of the combustion reaction.

[00488] In some embodiments, a temperature of the combustion heater 1809 may be maintained to be less than a threshold temperature by modulating the flow rate and/or pressure of the air stream 1818 supplied to the combustion heater 1809 (e.g., to enable a lower temperature catalytic combustion of the hydrogen).

[00489] In some embodiments, the flow of the air stream 1818 to the combustion heater 1809 may be reduced or shut off completely, which may decrease the temperature of the combustion heater 1809 to be less than a combustion temperature, and therefore the hydrogen may be vented (instead of combusted).

Air-Rich or Fuel-Lean Combustion

[00490] In some cases, the combustion reaction in the combustion heater 1809 may comprise an air-rich or fuel-lean condition (i.e., so that oxygen is in stoichiometric excess). In some cases, the fuel-lean combustion may increase thermal or energy efficiency of the reforming system 1800, since a substantial majority, or all, of the combustion fuel (e.g., the reformate stream 1820) is consumed. The fuel -lean combustion may enable a small amount (or none) of the H2 at the combustion exhaust 1814 to be flared or vented, which may reduce waste H2 since flared or vented H2 may not be used for power generation, or for chemical or industrial processes. In some cases, the fuel-lean combustion may prevent flammability of the combustion exhaust 1814, and therefore may enable a safe operation of the HC reforming system 1800.

[00491] In some cases, the air-rich or fuel -lean combustion in the combustion heater 1809 is maintained during at least about 10, 20, 30, 40, 50, 60, 70, 80, or 90% of the operational time of the operation mode. In some cases, the air-rich or fuel-lean combustion in the combustion heater 1809 is maintained during at most about 10, 20, 30, 40, 50, 60, 70, 80, or 90% of the operational time of the operation mode. In some cases, the air-rich or fuel-lean combustion in the combustion heater 1809 is maintained during of from about 10% to about 30%, of from about 20% to about 40%, of from about 30% to about 50%, of from about 40% to about 60%, of from about 50% to about 70%, of from about 60% to about 80%, or of from about 70% to about 90% of the operational time of the operation mode. Hydrogen Carrier as Combustion Fuel

[00492] In some cases, instead of combusting the reformate stream 1820, the combustion heater 1809 may combust hydrogen carrier to heat the combustion-heated reformer 1808. In some cases, at least part of the HC stream 1804 may be directed from the storage tank 1802 to the combustion heater 1809 to combust the HC stream 1804 to heat the reformer 1808. In some cases, an additional HC stream (separate from the HC stream 1804) may be directed from an additional storage tank (separate from the storage tank 1802) to the combustion heater 1809 to combust the additional HC stream to heat the reformer 1808.

[00493] In some cases, a pure HC stream (i.e., comprising only HC) may be directed to the combustion heater 1809 for combusting. In some cases, an HC stream mixed with a pilot fuel (i.e., a promoter fuel to facilitate combustion) is directed to the combustion heater 1809 for combusting. The pilot fuel may comprise a lower flash point compared to the HC and may comprise a higher flame speed when combusted compared to the HC. The pilot fuel may comprise hydrogen (for example, the hydrogen in the reformate stream 1820). In some cases, the pilot fuel is a hydrocarbon (that may be, for example, generated using renewable energy).

[00494] It is contemplated that for any embodiment of the present disclosure where the reformate stream 1820 is directed for combustion in the combustion heater 1809, the reformate stream 1820 may instead comprise HC for combustion in the combustion heater 1809. Therefore, is also contemplated that the amount of HC for combustion may be controlled (e.g., the flow rate of the HC may be increased or decreased) based on a stimulus (for example, the temperature of the reformer 1808 and/or the combustion heater 1809).

Pressure Drop Elements

[00495] FIGS. 23P-23R are block diagrams illustrating pressure drop elements 2326a-c configured to maintain an even distribution of fluid pressure to a plurality of components of the HC reforming system 1800. The pressure drop elements 2326a-c may comprise, for example, restricted orifices or apertures positioned in fluid lines and/or manifolds of the HC reforming system 1800. In some instances, the pressure drop element 2326a may be smaller in size (e.g., the radius of an orifice or aperture) than the pressure drop element 2326b, and in turn, the pressure drop element 2326b may be smaller in size than the pressure drop element 2326c. By homogenizing or equalizing the pressure of fluid provided to each of the components, the potential output of each respective component may be maximized.

[00496] In some instances, a pressure drop of the pressure drop element 2326a may be different from a pressure drop of the pressure drop elements 2326b and/or 2326c. In some instances, a pressure drop of the pressure drop element 2326a may be same as a pressure drop of the pressure drop elements 2326b and/or 2326c within a selected tolerance. The selected tolerance may be less than 20%.

[00497] For example, as shown in FIG. 23P, pressure drop elements 2326a-c may be configured to distribute the HC stream 1804 evenly to multiple reformers 1808-1810 (or sets of reformers 1808-1810). As shown in FIG. 23Q, pressure drop elements 2326a-c may be configured to distribute the reformate stream 1820 evenly to multiple combustion heaters 1809. As shown in FIG. 23R, pressure drop elements 2326a-c may be configured to distribute the reformate stream 1820 evenly to multiple fuel cells 1824.

[00498] In some cases, the one or more pressure drop elements illustrated in the FIGS. 23P-23R may distribute a flow rate of fluid to each of the reformers 1808-1810, combustion heaters 1809, or fuel cells 1824 within a selected tolerance of a target flow rate. In some cases, the selected tolerance is at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%, and at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100% of the target flow rate. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50%. For example, if the target flow rate to a reformer of a set of three reformers is about 100 slpm (standard liters per minute) within a selected tolerance of about 10%, each of the three reformers receives flow rate of about 90 to about 110 slpm.

[00499] In some cases, pressure drops across the one or more pressure drop elements may be changed or adjusted manually or electronically (e.g., with voltage and/or current signals). In some cases, one or more pressure drop elements, one or more valves, one or more pumps, one or more regulators, or any combination of thereof, may adjust or maintain a flow rates to the one or more fuel cells 124 within a selected tolerance of a target flow rate. In some cases, the selected tolerance is at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%, and at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50%. In some cases, the selected tolerance is less than about 20%.

[00500] In some cases, the one or more pressure drop elements illustrated in FIGS. 23P- 23R may be at least partly replaced by (or may comprise additional) one or more flow control units comprising one or more pumps, one or more check valves, one or more one-way valves, one or more three-way valves, one or more restrictive orifices, one or more valves, one or more flow regulators, one or more pressure regulators, one or more back pressure regulators, one or more pressure reducing regulators, one or more back flow regulators, one or more flow meters, one or more flow controllers, or any combination thereof. In some cases, the one or more flow control units may be controlled manually, automatically, or electronically. The one or more flow control units may maintain the desired flow rate distribution to the one or more reformers, one or more combustion heaters, or one or more fuel cells. The flow rate distribution may be even (or uneven) depending on predetermined flow processing capabilities of the one or more reformers, one or more combustion heaters, or one or more fuel cells.

[00501] In some cases, the one or more flow control units may distribute the flow to the reformers 1808-1810, combustion heaters 1809, or fuel cells 1824 within a selected tolerance of a target flow rate. In some cases, the selected tolerance is at least about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%, and at most about 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100%. In some cases, the selected tolerance may be between about 1 and 100, 5 and 90, 10 and 80, 20 and 70, 30 and 60, or 40 and 50%. For example, if the target flow rate to one reformer of a set of three reformers is about 100 slpm (standard liters per minute) with a selected tolerance of about 10%, each of the three reformers receives a flow rate of about 90 to about 110 slpm. In some cases, the selected tolerance is less than about 20%.

Hydrogen Separation Membrane

[00502] FIG. 23S is a block diagram illustrating a hydrogen separation device 2327 configured to separate hydrogen from the reformate stream 1820. The hydrogen separation device 2327 may comprise a retentate chamber 2328, a membrane 2329, and a permeate chamber 2330. The hydrogen separation device 2327 may increase the hydrogen purity of the reformate stream 1820, which may increase the hydrogen consumption rate or output voltage of the fuel cell 1824 when the high hydrogen purity reformate stream 1820 is provided to the fuel cell 1824. [00503] As the reformate stream 1820 passes the retentate chamber 2328, hydrogen may diffuse across the membrane 2329 into the permeate chamber 2330. The membrane 2329 may comprise platinum (Pt), palladium (Pd), vanadium (V), niobium (Nb), tantalum (Ta), an alloy thereof, or any combination thereof, although the present disclosure is not limited thereto. The permeate stream 2331 (comprising the separated hydrogen, e.g., 99% or more hydrogen) may then exit the hydrogen separation device 2327 (via an outlet in the permeate chamber 2330) and be provided to the fuel cell 1824 for electricity generation. In some cases, the retentate stream 2332 comprising at least portion of the hydrogen from the reformate stream 1820 may be supplied to the combustion heater 1809 as a combustion fuel.

Reforming HC to Provide Hydrogen for Internal Combustion Engine [00504] FIG. 23T is a block diagram illustrating an internal combustion engine (ICE) 2333 configured to combust the reformate stream 1820 (i.e., combust the hydrogen therein) to generate mechanical power (or electrical power). The ICE 2333 may comprise a reciprocating piston engine or a gas turbine.

[00505] In some embodiments, the ICE 2333 may be configured to combust the reformate stream 1820 (e.g., such that hydrogen is the sole or primary fuel). In some cases, the reformate stream 1820 may be co-combusted or co-fired with an additional fuel (e.g., auxiliary or secondary fuel), such that the hydrogen in the reformate stream 1820 is advantageously provided as a pilot fuel (promoter fuel) that facilitates combustion of the additional fuel in the ICE 2333.

[00506] The additional fuel may comprise HC (which, due to its low flame speed and high ignition chamber, is difficult to bum without a promoter fuel). The additional fuel comprising the HC may be provided from the storage tank 1802 (described with respect to FIGS. 18A-21B) to be co-combusted with the reformate stream 1820 in the ICE 2333. In some instances, the additional HC may be provided from a dedicated secondary storage tank that is separate from the storage tank 1802.

[00507] In some embodiments, the additional fuel comprises a hydrocarbon fuel, for example, gasoline, diesel, biodiesel, methane, biomethane, methanol, biomethanol, fatty-acid methyl ester (FAME), hydro-treated renewable diesel (HVO), Fischer-Tropsch (FT) diesel, marine oil, heavy fuel oil (HFO), marine diesel oil (MDO), and/or dimethyl ether (DME).

[00508] In some embodiments, the additional fuel comprises a synthetic renewable fuel (e.g., scalable zero emissions fuel (SZEF)) produced using at least one of carbon capture, renewable electricity, or renewable hydrogen.

[00509] In some embodiments, a heat exchanger 2334 may be utilized to transfer heat from an exhaust of the ICE 2333 to the combustion heated reformer 18a08 and/or the electrically-heated reformer 1810. This heat transfer may increase the overall energy efficiency of the HC reforming system 1800.

Methods of Initiating HC Reforming

[00510] FIGS. 24-28C are a flow charts illustrating various methods of initiating HC reforming (e.g., startup processes for the HC reforming system 1800). It is noted that the method steps described with respect to FIGS. 24-28C may be performed using a controller (for example, by executing program instructions using the controller 2200) in response to a stimulus. The stimulus may comprise a manual input (e.g., user input), and/or an automated input. The automated input may comprise a sensor measurement (e.g., measured by sensors P1-P10, Tl- Ti l, FM1-FM11, and HCC1-HCC10) being greater than or less than a threshold (e.g., threshold temperature, threshold pressure, threshold flow rate, and so on).

[00511] For example, the controller may actuate a flow control unit (e.g., open or close a valve), and direct a fluid (e.g., HC stream 1804, reformate stream 1820, air stream 1818, anode off-gas 1828) by increasing or decreasing a flow rate of the fluid (in response or based on the manual input or the automated input). In another example, the controller may increase or decrease heating power to the electrical heater (e.g., electrical heater 1811) (in response or based on the manual input or the automated input). In another example, the controller may increase or decrease the load at the fuel cell (e.g., fuel cell 1824) (in response or based on the manual input or the automated input).

First Example Method of Initiating HC Reforming

[00512] FIG. 24 is a flow chart illustrating a method of initiating HC reforming.

[00513] At step 2401, an electrically-heated reformer (e.g., electrically-heated reformer 1810) may be heated (e.g., using electrical heater 1811) to a target temperature (within a target temperature range, for example, about 400 - about 600 °C). The electrically-heated reformer may be heated by initiating power supply to the electrical heater.

[00514] At step 2402, HC (e.g., incoming HC stream 1804) may be directed to the electrically-heated reformer, and HC may be reformed using reforming catalysts in the electrically-heated reformer to generate hydrogen (e.g., reformate stream 1820).

[00515] At step 2403, at least a portion of the reformate stream (generated by the electrically-heated reformer) may be reacted with air (e.g., air stream 1818) in a combustion reaction (e.g., in the combustion heater 1809) to heat the combustion-heated reformer (e.g., combustion-heated reformer 1809).

[00516] At step 2404, the electrically-heated reformer may be optionally turned off or reduced (e.g., after the combustion-heated reformer reaches a target temperature range). The electrically-heated reformer may be turned off or reduced by reducing the power supply to the electrical heater.

[00517] At step 2405, the flow rate of the incoming HC flow may be increased to a predefined flow rate (e.g., to generate a target flow rate of H2 in the reformate stream).

[00518] In some cases, step 2401 and step 2402 may be performed in sequence or in parallel. In some cases, at least two steps in steps 2401-2405 may be performed in sequence or in parallel. Once step 2405 is performed, and self-sustained auto-thermal reforming is maintained (i.e., at a steady-state condition, or predetermined operational condition), the HC flow rate may be further increased above a predefined rate depending on operating requirements (e.g., fuel cell output power, electrically-heated reformer temperature(s), combustion-heated reformer temperature(s), reactor pressure(s), HC flowrate, etc.) while maintaining auto-thermal reforming. Step 2404 may be executed or unexecuted depending on combustion-heated reformer temperature and HC conversion efficiency.

[00519] In some embodiments, instead of the combustion-heated reformer, the electrically-heated reformer may provide the majority or all of the hydrogen in the reformate stream (e.g., greater than about 50% of the hydrogen by volume).

Second Example Method of Initiating HC Reforming

[00520] FIG. 25 is a flow chart illustrating a method of initiating HC reforming.

[00521] At step 2501, an electrically-heated reformer (e.g., electrically-heated reformer 1810) may be heated (e.g., using electrical heater 1811) to a target temperature (within a target temperature range, for example, about 400 - about 600 °C). The electrically-heated reformer may be heated by initiating power supply to the electrical heater.

[00522] At step 2502, HC (e.g., incoming HC stream 1804) may be directed to the electrically-heated reformer, and HC may be reformed using reforming catalysts in the electrically-heated reformer to generate hydrogen (e.g., reformate stream 1820).

[00523] At step 2503, at least a portion of the reformate stream (generated by the electrically-heated reformer) and air (e.g., air stream 1818) may be directed to the combustion heater.

[00524] At step 2504, the reformate stream may be reacted with the air in a combustion reaction (in the combustion heater 1809) to heat the combustion-heated reformer (e.g., combustion-heated reformer 1809). An ignition device (e.g., spark plug) may be activated to ignite the reformate and air in the combustion heater. The flow rate of the air to the combustion heater may be adjusted to increase the temperature of the combustion-heated reformer. In some instances, the flow rate of the air is modulated to maintain a target temperature ramp rate of the combustion-heated reformer.

[00525] At step 2505, HC (e.g., incoming HC stream 1804) may be reformed (after the combustion-heated reformer reaches a target temperature range) using HC reforming catalysts in the combustion-heated reformer to generate hydrogen (e.g., reformate stream 1820). In some instances, the combustion-heated reformer may fluidically communicate in series (e.g., as shown in FIG. 30) or in parallel with the electrically-heated reformer. [00526] At step 2506, heating the electrically-heated reformer may be optionally turned off or reduced (e.g., after the combustion-heated reformer reaches a target temperature range). The electrically-heated reformer may be turned off or reduced by reducing the power supply to the electrical heater.

[00527] At step 2507, the flow rate of the incoming HC stream may be incrementally increased to a predefined flow rate (e.g., to generate a target flow rate of H2 in the reformate stream). Simultaneously, the flow rate of the air stream (to the combustion heater) may be increased. By simultaneously increasing both the flow rate of the incoming HC stream and the flow rate of the air stream, the combustion-heated reformer may be maintained in a target temperature range.

[00528] At step 2508, the reformate generated by the combustion-heated reformer (and optionally the reformate generated by the electrically-heated reformer) may be directed (e.g., using one or more flow control units, pumps, valves, and/or regulators) to the fuel cell (e.g., fuel cell 1824).

[00529] At step 2509, the fuel cell may generate an electrical power output (to supply to an electrical load, e.g., an electrical grid, an electrical battery, or a motor for a vehicle).

[00530] At step 2510, the anode off-gas from the fuel cell (e.g., anode off-gas 1828) may be optionally directed to the combustion heater to be combusted. For example, a three-way valve may direct the reformate from (1) being provided directly to the combustion heater to (2) being provided to the fuel cell (and, subsequently, the anode off-gas may be provided to the combustion-heater). In some instances, the step 2510 is performed before the step 2509, or may executed simultaneously.

[00531] At step 2511, the flow rate of the incoming HC stream and the flow rate of the air stream may be adjusted to maintain the target temperature in the combustion-heated reformer.

[00532] At step 2512, the HC reforming method (or system) may achieve a predetermined operational condition (steady-state condition)

[00533] It is noted that step 2506 may be executed or unexecuted based on the combustion-heated reformer temperature. For example, step 2506 may be unexecuted based on the combustion-heated reformer temperature being less than a predetermined threshold temperature. Step 2509 may be executed any time after step 2508.

Third Example Method of Initiating HC Reforming

[00534] FIG. 26 is a flow chart illustrating a method of initiating HC reforming. [00535] At step 2601, an electrically-heated reformer (e.g., electrically-heated reformer 1810) may be heated (e.g., using electrical heater 1811) to a target temperature (within a target temperature range, for example, about 400 - about 600 °C). The electrically-heated reformer may be heated by initiating power supply to the electrical heater.

[00536] At step 2602, HC (e.g., incoming HC stream 1804) may be directed to the electrically-heated reformer, and HC may be reformed using reforming catalysts in the electrically-heated reformer to generate hydrogen (e.g., reformate stream 1820).

[00537] At step 2603, at least a portion of the reformate stream (generated by the electrically-heated reformer) may be directed to a fuel cell 1824.

[00538] At step 2604, the anode off-gas from the fuel cell (e.g., anode off-gas 1828) may be optionally directed to a combustion heater to be combusted with air (e.g., air stream 1818). An ignition device (e.g., spark plug) may be activated to ignite the anode off-gas and air in the combustion heater. The flow rate of the air to the combustion heater may be adjusted to increase the temperature of the combustion-heated reformer.

[00539] At step 2605, the fuel cell may generate an electrical power output (to supply to an electrical load, e.g., a motor for a vehicle). In some instances, the step 2605 may be performed before the step 2604 or may performed simultaneously.

[00540] At step 2606, HC (e.g., incoming HC stream 1804) may be reformed (after the combustion-heated reformer reaches a target temperature range) using reforming catalysts in the combustion-heated reformer to generate hydrogen (e.g., reformate stream 1820). In some cases, the combustion-heated reformer may fluidically communicate in series (e.g., as shown in FIG. 30) or in parallel with the electrically-heated reformer.

[00541] At step 2607, heating the electrically-heated reformer may be optionally turned off or reduced (e.g., after the combustion-heated reformer reaches a target temperature range). The electrically-heated reformer may be turned off or reduced by reducing the power supply to the electrical heater.

[00542] At step 2608, the flow rate of the incoming HC stream may be incrementally increased to a predefined flow rate (e.g., to generate a target flow rate of H2 in the reformate stream). Simultaneously, the flow rate of the air stream (to the combustion heater) may be increased. By simultaneously increasing both the flow rate of the incoming HC stream and the flow rate of the air stream, the combustion-heated reformer may be maintained in a target temperature range. [00543] At step 2609, optionally, the flow rate of the incoming HC stream and the flow rate of the air stream may be further adjusted to maintain the target temperature in the combustion-heated reformer.

[00544] At step 2610, the HC reforming method (or system) may achieve a predetermined operational condition (steady-state condition)

[00545] It is noted that step 2607 may be executed or unexecuted based on the combustion-heated reformer temperature. For example, step 2607 may be unexecuted based on the combustion-heated reformer temperature being less than a predetermined threshold temperature. Step 2605 may be executed any time after step 2603.

Fourth Example Method of Initiating HC Reforming

[00546] FIG. 27 is a flow chart illustrating a method of initiating HC reforming.

[00547] At step 2701, an electrically-heated reformer (e.g., electrically-heated reformer 1810) may be heated (e.g., using electrical heater 1811) to a target temperature (within a target temperature range, for example, about 400 - about 600 °C). The electrically-heated reformer may be heated by initiating power supply to the electrical heater.

[00548] At step 2702, HC (e.g., incoming HC stream 1804) may be directed to the electrically-heated reformer, and HC may be reformed using reforming catalysts in the electrically-heated reformer to generate hydrogen (e.g., reformate stream 1820).

[00549] At step 2703, at least a portion of the reformate stream (generated by the electrically-heated reformer) and air (e.g., air stream 1818) may be directed to the combustion heater.

[00550] At step 2704, the reformate stream may be reacted with the air in a combustion reaction (in the combustion heater 1809) to heat the combustion-heated reformer (e.g., combustion-heated reformer 1809). An ignition device (e.g., spark plug) may be activated to ignite the reformate and air in the combustion heater. The flow rate of the air to the combustion heater may be adjusted to increase the temperature of the combustion-heated reformer.

[00551] At step 2705, HC (e.g., incoming HC stream 1804) may be reformed (after the combustion-heated reformer reaches a target temperature range) using reforming catalysts in the combustion-heated reformer to generate hydrogen (e.g., reformate stream 1820). In some cases, the combustion-heated reformer may fluidically communicate in series (e.g., as shown in FIG. 30) or in parallel with the electrically-heated reformer.

[00552] At step 2706, the flow rate of the incoming HC stream may be incrementally increased to a predefined flow rate (e.g., to generate a target flow rate of H2 mixture in the reformate stream). Simultaneously, the flow rate of the air stream (to the combustion heater) may be increased. By simultaneously increasing both the flow rate of the incoming HC stream and the flow rate of the air stream, the combustion-heated reformer may be maintained in a target temperature range.

[00553] At step 2707, the HC reforming method (or system) may achieve a predetermined operational condition (steady-state condition)

Methods of Initiating HC Reforming System

[00554] FIGS. 28A-28C are flow charts illustrating various methods of initiating an HC reforming system (e.g., HC reforming system 1800) to power a device. The device may be a load powered by a fuel cell of the HC reforming system (for example, an electrical motor for a mobile vehicle, a stationary data center, a cell phone tower, or a charging station) or an internal combustion engine powered by reformate generated by the HC reforming system.

Method of Initiating HC Reforming System using Battery

[00555] FIG. 28A is a flow chart illustrating a method of initiating an HC reforming system using a battery (to power a device).

[00556] At step 2801, the device may be started. For example, an electrical vehicle or device may be switched on.

[00557] At step 2802, the HC reforming system may be started using a battery. For example, an electrical heater may receive electrical power from the battery to heat an electrically-heated reformer, and HC may be reformed using the reforming catalysts in the electrically-heated reformer.

[00558] At step 2803, the HC reforming system may be further operated. For example, any of the steps described with respect to FIGS. 24-27 may be executed or performed.

[00559] At step 2804, the device may be stopped. For example, an electrical vehicle or device may be switched off.

[00560] At step 2805, the HC reforming system may charge the battery (for example, by providing fuel cell power to the battery). In some embodiments, an electrical grid (e.g., external electrical grid) may charge the battery.

Method of Initiating HC Reforming System using Stored Hydrogen

[00561] FIG. 28B is a flow chart illustrating a method of initiating an HC reforming system using stored hydrogen (to power a device). [00562] At step 2801, the device may be started. For example, an electrical vehicle or device may be switched on.

[00563] At step 2802, the HC reforming system may be started using stored hydrogen (e.g., stored in a hydrogen storage tank). For example, a combustion heater may combust the hydrogen and air to heat a combustion-heated reformer, and HC may be reformed using the reforming catalysts in the combustion-heated reformer.

[00564] At step 2803, the HC reforming system may be further operated. For example, any of the steps described with respect to FIGS. 24-27 may be executed or performed.

[00565] At step 2804, the device may be stopped. For example, an electrical vehicle may be switched off.

[00566] At step 2805, the HC reforming system may generate hydrogen, and store the hydrogen (e.g., in the hydrogen storage tank). It is noted that reformate (e.g., hydrogen) may be stored in the hydrogen storage tank.

Method of Initiating HC Reforming System using Electrical Grid

[00567] FIG. 28C is a flow chart illustrating a method of initiating an HC reforming system using an electrical grid (to power a device).

[00568] At step 2801, the device may be started. For example, a cell phone tower or charging device may be switched on.

[00569] At step 2802, the HC reforming system may be started using electrical power from an electrical grid. For example, an electrical heater may receive electrical power from the electrical grid to heat an electrically-heated reformer, and HC may be reformed using the reforming catalysts in the electrically-heated reformer.

[00570] At step 2803, the HC reforming system may be further operated. For example, any of the steps described with respect to FIGS. 24-27 may be executed or performed.

[00571] At step 2804, the device may be stopped. For example, a cell phone tower or charging device may be switched off.

Method of Operating HC Reforming System

[00572] FIG. 29A is a flow chart illustrating a method of operating HC reforming (e.g., HC reforming system 1800), in accordance with one or more embodiments of the present disclosure.

[00573] At step 2901, for a set of given system operational parameters, self-sustaining auto-thermal operational conditions may be predetermined (e.g., minimum and maximum HC flow rates, corresponding fuel cell (FC) power and hydrogen consumption rates, minimum and maximum battery states of charge (SOC), minimum and maximum air flow rates, etc.).

[00574] At step 2902, operational parameters may be maintained and/or adjusted to maintain and/or adjust fuel cell power output (and self-sustained autothermal reforming).

[00575] At step 2903, the method may comprise monitoring the power output of the fuel cell, and automatically or manually adjusting (increasing or decreasing) the power output (based on the electrical load coupled to the fuel cell). The method may adjust various operational parameters including the flow rate of the air stream to the combustion heater, the flow rate of the incoming HC stream, the hydrogen consumption rate of the fuel cell, and/or the electrical power to the electrical heater. In some cases, a controller may control HC flow rate, control air flow rate, control HC flow pressures, control air flow pressures, control valves, control FC power output, control battery power output, control E-reformer power input, control FC hydrogen consumption rate, or any combination thereof. In some cases, one or more sensors may measure temperatures, pressures, fuel cell power output, battery power outputs, battery SOC, fuel cell hydrogen consumption rate, HC conversion efficiency, or any combination thereof.

[00576] At step 2904, based on the fuel cell power being less than the electrical load power, the method may comprise increasing the power output of the fuel cell. The hydrogen consumption rate of the fuel cell may be compared to a predetermined threshold consumption rate (the threshold consumption rate may be a specific value or a range).

[00577] At step 2905, based on the hydrogen consumption rate being less than the predetermined threshold, the method may comprise increasing the power output of the fuel cell by increasing the hydrogen consumption rate (while still keeping the hydrogen consumption rate less than the predetermined threshold). The method may then proceed to step 2901.

[00578] At step 2906, based on the hydrogen consumption rate of the fuel cell being equal to or above the predetermined threshold, the method may comprise comparing the HC flow rate into the system to a predetermined HC flow rate. In some cases, the predetermined HC flow rate may be a maximum HC flow rate for the system.

[00579] At step 2907, the method may comprise increasing the HC flow rate (based on the flow rate of the incoming HC stream being less than the predetermined HC flow rate). The method may then proceed to step 2901.

[00580] At step 2908, the method may comprise maintaining the HC flow rate (based on the flow rate of the incoming HC stream being greater than the predetermined HC flow rate).

[00581] At step 2909, the method may comprise maintaining the power output of the fuel cell (based on the flow rate of the incoming HC stream being equal to or greater than the -I l l- predetermined HC flow rate). In some cases, the power output of the fuel cell may be a maximum power output of the fuel cell. The method may then proceed to step 2901.

[00582] At step 2910, based on the fuel cell power being greater than the electrical load power, the method may comprise decreasing the power output of the fuel cell. Otherwise, the fuel cell power may not be decreased, and the method may proceed to step 2901.

[00583] At step 2911, the method may comprise comparing the flow rate of the incoming HC stream to a predetermined HC flow rate. In some cases, the predetermined HC flow rate may be a minimum HC flow rate. In some cases, regardless of the flow rate of the incoming HC stream being equal to or greater than the minimum HC flow rate, method may proceed to step 2901.

[00584] At step 2912, the method may comprise reducing the flow rate of the incoming HC stream (based on the flow rate of the incoming HC stream being greater than the predetermined HC flow rate). The method may then proceed to step 2901.

[00585] At step 2913, the method may comprise maintaining the flow rate of the incoming HC stream (based on the flow rate of the incoming HC stream being equal to or less than the predetermined HC flow rate).

[00586] At step 2914, the method may comprise maintaining the power output of the fuel cell (based on the flow rate of the incoming HC stream being equal to or less than the predetermined HC flow rate). The method may then proceed to step 2901.

[00587] In some cases, at step 2911, the method may or may not comprise comparing the flow rate of the incoming HC stream to a predetermined HC flow rate. Regardless of the flow rate of the incoming HC stream being less than, equal to, or greater than the predetermined HC flow rate, the method may further comprise maintaining the flow rate of the incoming HC stream and proceeding to step 2901. In some cases, the predetermined HC flow rate may be a minimum HC flow rate. In this way, the fuel cell power is reduced and the incoming HC flow rate is maintained or at least within a desired range.

[00588] In some cases, the method may comprise a shutdown process. In some cases, the shutdown process may comprise reducing any one of or a combination of HC flow rate, air flow rate, and fuel cell power to zero.

[00589] In some cases, the method may comprise performing or executing a hot standby mode. In some cases, performing or executing the hot standby mode may comprise reducing the HC flow rate, air flow rate, and/or the fuel cell power to zero.

Method of Operating HC Reforming System Using a Battery [00590] FIG. 29B is a flow chart illustrating a method of operating HC reforming (e.g., HC reforming system 1800) using a battery, in accordance with one or more embodiments of the present disclosure.

[00591] At step 2915, for a set of given system operational parameters, self-sustaining auto-thermal operational conditions may be predetermined (e.g., minimum and maximum HC flow rates, corresponding FC power and hydrogen consumption rates, minimum and maximum battery states of charge (SOC), minimum and maximum air flow rates, etc.).

[00592] At step 2916, operational parameters may be maintained and/or adjusted to maintain and/or adjust fuel cell power output (and self-sustained autothermal reforming).

[00593] At step 2917, the method may comprise monitoring the power output of the fuel cell, and automatically or manually adjusting (increasing or decreasing) the power output (based on the electrical load coupled to the fuel cell). The method may adjust various operational parameters including the flow rate of the air stream to the combustion heater, the flow rate of the incoming HC stream, the hydrogen consumption rate of the fuel cell, and/or the electrical power to the electrical heater. In some cases, one or more controllers may control HC flow rate, control air flow rate, control HC flow pressures, control air flow pressures, control valves, control FC power output, control battery power output, control E-reformer power input, control FC hydrogen consumption rate, or any combination thereof. In some cases, one or more sensors may measure temperatures, pressures, fuel cell power output, battery power outputs, battery SOC, fuel cell hydrogen consumption rate, and HC conversion efficiency.

[00594] At step 2918, based on the fuel cell power being less than the electrical load power, the method may comprise comparing the FC hydrogen consumption rate to a predetermined threshold FC hydrogen consumption rate. In some cases, the predetermined threshold FC hydrogen consumption rate may be a maximum consumption rate.

[00595] At step 2919, based on the hydrogen consumption rate being less than the predetermined threshold, the method may comprise increasing the power output of the fuel cell by increasing the hydrogen consumption rate (while still keeping the hydrogen consumption rate less than the predetermined threshold). The method may then proceed to step 2915.

[00596] At step 2920, based on the hydrogen consumption rate of the fuel cell being equal to or above the predetermined threshold, the battery may be used to provide electrical power to the electrical load.

[00597] At step 2921, the battery state of charge (SOC) may be compared to a predetermined minimum threshold. [00598] At step 2922, based on the battery SOC being less than the predetermined minimum threshold, the flow rate of the incoming HC stream may be compared to a predetermined HC flow rate. In some cases, the predetermined HC flow rate may be a maximum HC flow rate for the system.

[00599] At step 2923, the method may comprise increasing the flow rate of the incoming HC stream (based on the flow rate of the incoming HC stream being less than the predetermined HC flow rate). The method may then proceed to step 2915.

[00600] At step 2924, the method may comprise maintaining the flow rate of the incoming HC stream (based on the flow rate of the incoming HC stream being equal to or greater than the predetermined HC flow rate).

[00601] At step 2925, the method may comprise limiting an electrical load associated with the power demand. The method may then proceed to step 2915.

[00602] At step 2926, the method may comprise decreasing the power output of the fuel cell, and comparing a battery SOC to a predetermined threshold.

[00603] At step 2927, based on the battery SOC being equal to or greater than the predetermined threshold, the method may comprise comparing the flow rate of the incoming HC stream to a predetermined HC flow rate. In some cases, the predetermined HC flow rate may be a minimum HC flow rate. Based on the flow rate of the incoming HC stream being less than the predetermined HC flow rate, method may then proceed to step 2928.

[00604] In some cases, at step 2927, regardless of the flow rate of the incoming HC stream being equal to or greater than the minimum HC flow rate, method may comprise reducing the fuel cell power output and proceed to step 2915. In this way, the fuel cell power is reduced and the incoming HC flow rate is maintained or at least within a desired range.

[00605] At step 2928, the method may comprise reducing the flow rate of the incoming HC stream (based on the flow rate of the incoming HC stream being greater than the predetermined HC flow rate). The method may then proceed to step 2915.

[00606] At step 2929, based on the battery SOC being less than the predetermined threshold, the method may comprise charging the battery using electrical power generated by the fuel cell.

[00607] At step 2930, the method may comprise determining if the battery is fully charged. Based on the battery being fully charged, the method may proceed to step 2927 or step 2915. Based on the battery being less than fully charged, the method may proceed to step 2915. [00608] In some cases, the method may comprise a shutdown process. In some cases, the shutdown process may comprise reducing any one of or a combination of HC flow rate, air flow rate, and fuel cell power to zero.

[00609] In some cases, the method may comprise performing or executing a hot standby mode. In some cases, performing or executing the hot standby mode may comprise reducing the HC flow rate, the air flow rate, and/or the fuel cell power to zero.

[00610] In some cases, by combining any of the methods illustrated in FIG 29A-29B, the method may comprise the fuel cell providing power to the battery, and the battery may provide power for the electrical load. In some cases, the fuel cell may provide power to charge the battery, and the battery may provide power for the electrical load. In some cases, if the battery SOC is close to, equal to, or above the predetermined threshold maximum SOC, the system may execute the hot standby mode, or shut down the HC reforming system. In some cases, if the battery SOC falls below the threshold maximum SOC, the system may unexecute the hot standby mode and generate power from the fuel cell.

Oxidation Resistant Catalyst for Purging

[00611] FIG. 30 is a schematic diagram illustrating utilization of an oxidation-resistant catalyst 3001 to generate reformate to purge the HC reforming system 1800 shown in FIGS. 18A-21B, in accordance with one or more embodiments of the present disclosure.

[00612] In some cases, the electrically-heated reformer 1810 may comprise oxidationresistant catalyst 3001 therein. The electrical heater 1811 may heat the electrically-heated reformer 1810 and the catalyst 3001 to a target temperature range (e.g., about 400 - about 600 °C). The oxidation-resistant catalyst 3001 may be configured to resist oxidation at the target temperature range.

[00613] HC may then be reformed at the target temperature range using the oxidationresistant catalyst 3001 to generate a reformate stream 3002 comprising hydrogen (H2).

[00614] The reformate stream 3002 may then be provided to the reformer 1808 filled with oxidation-sensitive catalyst 3003. In contrast to the oxidation-resistant catalyst 3001, the oxidation-sensitive catalyst 3003 may be sensitive to oxidation at the target temperature range (e.g., about 400 - about 600 °C) and/or in an environment comprising oxygen. The reformate stream 3004 (purging gas) may purge any residual gases or liquids in the reformer 1808 (e.g., residual HC).

[00615] It is noted that, the oxidation-resistant catalyst 3001 may be configured to generate reformate to purge residual gases in any type of reactor, and that the present disclosure is not limited to purging residual gases in the reformer 1808 and/or 1810. For example, the oxidation resistant catalyst 3001 may be used to generate reformate to purge a steam methane reforming (SMR) reactor, a methanol reforming reactor, or any other type of reactor.

Computer Systems

[00616] In an aspect, the present disclosure provides computer systems that are programmed or otherwise configured to implement methods of the disclosure. FIG. 31 shows a computer system 3101 that is programmed or otherwise configured to implement methods of thje present disclosure (e.g., processing hydrogen and/or mixtures of hydrogen and nitrogen). In some embodiments, the computer system is configured to operate any of the fuel cells described herein (e.g., any fuel cell described with respect to FIGS. 1-30) to allow purging of nitrogen from the fuel cell while the fuel cell is generating electricity. In some embodiments, the computer system is configured to operate the fuel cell to allow continuous purging of nitrogen. The computer system 3101 may be configured to, for example, (i) control a flow of a source material comprising hydrogen and nitrogen to one or more fuel cells and (ii) control an operation of the one or more fuel cells to process the source material to generate electricity (e.g., an electrical current). The computer system 3101 can be an electronic device of a user or a computer system that is remotely located with respect to the electronic device. The electronic device can be a mobile electronic device.

[00617] The computer system 3101 may include a central processing unit (CPU, also "processor" and "computer processor" herein) 3105, which can be a single core or multi core processor, or a plurality of processors for parallel processing. The computer system 3101 also includes memory or memory location 3110 (e.g., random-access memory, read-only memory, flash memory), electronic storage unit 3115 (e.g., hard disk), communication interface 3120 (e.g., network adapter) for communicating with one or more other systems, and peripheral devices 3125, such as cache, other memory, data storage and/or electronic display adapters. The memory 3110, storage unit 3115, interface 3120 and peripheral devices 3125 are in communication with the CPU 3105 through a communication bus (solid lines), such as a motherboard. The storage unit 3115 can be a data storage unit (or data repository) for storing data. The computer system 3101 can be operatively coupled to a computer network ("network") 3130 with the aid of the communication interface 3120. The network 3130 can be the Internet, an internet and/or extranet, or an intranet and/or extranet that is in communication with the Internet. The network 3130 in some cases is a telecommunication and/or data network. The network 3130 can include one or more computer servers, which can enable distributed computing, such as cloud computing. The network 3130, in some cases with the aid of the computer system 3101, can implement a peer-to-peer network, which may enable devices coupled to the computer system 3101 to behave as a client or a server.

[00618] The CPU 3105 can execute a sequence of machine-readable instructions, which can be embodied in a program or software. The instructions may be stored in a memory location, such as the memory 3110. The instructions can be directed to the CPU 3105, which can subsequently program or otherwise configure the CPU 3105 to implement methods of the present disclosure. Examples of operations performed by the CPU 3105 can include fetch, decode, execute, and writeback.

[00619] The CPU 3105 can be part of a circuit, such as an integrated circuit. One or more other components of the system 3101 can be included in the circuit. In some cases, the circuit is an application specific integrated circuit (ASIC).

[00620] The storage unit 3115 can store files, such as drivers, libraries and saved programs. The storage unit 3115 can store user data, e.g., user preferences and user programs. The computer system 3101 in some cases can include one or more additional data storage units that are located external to the computer system 3101 (e.g., on a remote server that is in communication with the computer system 3101 through an intranet or the Internet).

[00621] The computer system 3101 can communicate with one or more remote computer systems through the network 3130. For instance, the computer system 3101 can communicate with a remote computer system of a user (e.g., an individual operating a reactor from which the source material comprising hydrogen and nitrogen is produced, an entity monitoring the operation of the reactor or one or more fuel cells operatively coupled to the reactor, or an end user operating a device or a vehicle that can be powered using electrical energy derived or produced from the source material using the one or more fuel cells). Examples of remote computer systems include personal computers (e.g., portable PC), slate or tablet PC's (e.g., Apple® iPad, Samsung® Galaxy Tab), telephones, Smart phones (e.g., Apple® iPhone, Android-enabled device, Blackberry®), or personal digital assistants. The user can access the computer system 3101 via the network 3130.

[00622] Methods as described herein can be implemented by way of machine (e.g., computer processor) executable code stored on an electronic storage location of the computer system 3101, such as, for example, on the memory 3110 or electronic storage unit 3115. The machine executable or machine readable code can be provided in the form of software. During use, the code can be executed by the processor 3105. In some cases, the code can be retrieved from the storage unit 3115 and stored on the memory 3110 for ready access by the processor 3105. In some situations, the electronic storage unit 3115 can be precluded, and machineexecutable instructions are stored on memory 3110.

[00623] The code can be pre-compiled and configured for use with a machine having a processor adapted to execute the code, or can be compiled during runtime. The code can be supplied in a programming language that can be selected to enable the code to execute in a precompiled or as-compiled fashion.

[00624] Aspects of the systems and methods provided herein, such as the computer system 3101, can be embodied in programming. Various aspects of the technology may be thought of as "products" or "articles of manufacture" typically in the form of machine (or processor) executable code and/or associated data that is carried on or embodied in a type of machine readable medium. Machine-executable code can be stored on an electronic storage unit, such as memory (e.g., read-only memory, random-access memory, flash memory) or a hard disk. "Storage" type media can include any or all of the tangible memory of the computers, processors or the like, or associated modules thereof, such as various semiconductor memories, tape drives, disk drives and the like, which may provide non-transitory storage at any time for the software programming. All or portions of the software may at times be communicated through the Internet or various other telecommunication networks. Such communications, for example, may enable loading of the software from one computer or processor into another, for example, from a management server or host computer into the computer platform of an application server. Thus, another type of media that may bear the software elements includes optical, electrical and electromagnetic waves, such as used across physical interfaces between local devices, through wired and optical landline networks and over various air-links. The physical elements that carry such waves, such as wired or wireless links, optical links or the like, also may be considered as media bearing the software. As used herein, unless restricted to non-transitory, tangible "storage" media, terms such as computer or machine "readable medium" refer to any medium that participates in providing instructions to a processor for execution.

[00625] Hence, a machine readable medium, such as computer-executable code, may take many forms, including but not limited to, a tangible storage medium, a carrier wave medium or physical transmission medium. Non-volatile storage media including, for example, optical or magnetic disks, or any storage devices in any computer(s) or the like, may be used to implement the databases, etc. shown in the drawings. Volatile storage media include dynamic memory, such as main memory of such a computer platform. Tangible transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. Carrier-wave transmission media may take the form of electric or electromagnetic signals, or acoustic or light waves such as those generated during radio frequency (RF) and infrared (IR) data communications. Common forms of computer-readable media therefore include for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD or DVD-ROM, any other optical medium, punch cards paper tape, any other physical storage medium with patterns of holes, a RAM, a ROM, a PROM and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer may read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.

[00626] The computer system 3101 can include or be in communication with an electronic display 3135 that comprises a user interface (UI) 3140 for providing, for example, a portal for a user to monitor or track an operation or a performance of the one or more fuel cells. In some cases, the performance of the one or more fuel cells may comprise, for example, a voltage of the electrical current generated using the one or more fuel cells. The portal may be provided through an application programming interface (API). A user or entity can also interact with various elements in the portal via the UI. Examples of UI's include, without limitation, a graphical user interface (GUI) and web-based user interface.

[00627] Methods and systems of the present disclosure can be implemented by way of one or more algorithms. An algorithm can be implemented by way of software upon execution by the central processing unit 3105. For example, the algorithm may be configured to control an operation of the one or more fuel cells based on one or more sensor readings (e.g., temperature measurements, flow rates, etc.), based on a power demand, or based on a performance of the one or more fuel cells. The algorithm can be configured to operate the fuel cell to allow purging of nitrogen from the fuel cell while the fuel cell is generating electricity, or to operate the fuel cell to allow continuous purging of nitrogen.

Vehicles

[00628] In some cases, the one or more fuel cells may be adapted for use on an aerial vehicle. The aerial vehicle may comprise, for example, a manned aerial vehicle, an unmanned aerial vehicle, or a drone. In some cases, the fuel cells may be integrated into a body of the aerial vehicle. In other cases, the fuel cells may be placed on top of or underneath a body of the aerial vehicle. In some cases, the fuel cells may be electrically coupled to a motor or an engine of the aerial vehicle. [00629] In some cases, the one or more fuel cells may be adapted for use on a terrestrial vehicle, such as a car, a farming vehicle, or an automobile. The one or more fuel cells may be placed in or near a front portion of the terrestrial vehicle (e.g., in an engine bay of the vehicle). The one or more fuel cells may be placed in or near an underside region of the terrestrial vehicle. The one or more fuel cells may be placed near a rear end of the terrestrial vehicle. In some cases, the one or more fuel cells may be placed near an axle of the terrestrial vehicle (e.g., a front wheel axle and/or a rear wheel axle of the vehicle). In some cases, the fuel cells may be electrically coupled to a motor or an engine of the terrestrial vehicle.

[00630] In some cases, the one or more fuel cells may be adapted for use on a terrestrial vehicle, such as a truck or a semi-trailer truck. In some cases, the one or more fuel cells may be coupled to or integrated into a rear portion of a tractor unit of the truck. The tractor unit (also known as a prime mover, truck, semi-truck, semi-tractor, rig, big rig, or simply, a tractor) may comprise a heavy-duty towing engine that provides motive power for hauling a towed or trailered-load. In some cases, the one or more fuel cells may be positioned in or near a front portion of the tractor unit (e.g., in the engine bay of the tractor unit). In other cases, the one or more fuel cells may be placed in or near an underside region of the tractor unit. In some cases, the plurality of fuel cells may be distributed along the underside of the tractor unit. In some cases, one or more of the fuel cells may be placed near an axle (e.g., a front axle) of the tractor unit.

[00631] In some cases, the one or more fuel cells may be adapted for use in a marine vehicle. The marine vehicle may comprise, for example, a manned marine vehicle, an unmanned marine vehicle, a boat, or a ship. In some cases, the fuel cells may be integrated into a body of the marine vehicle. In other cases, the fuel cells may be placed on top of or underneath a body of the marine vehicle. In some cases, the fuel cells may be electrically coupled to a motor or an engine of the marine vehicle. In some cases, the fuel cells may provide a back-up power of the marine vehicle. In some cases, the one or more fuel cells may be adapted for use in a submarine vehicle. In some cases, the fuel cells may be electrically coupled to a motor or an engine of the submarine vehicle.

[00632] In some cases, a vehicle may comprise a plurality of fuel cells. In some cases, the plurality of fuel cell modules may be positioned adjacent to each other. In other cases, the plurality of fuel cell modules may be located remote from each other (i.e., in or on different sides, regions, or sections of a vehicle). In some cases, the plurality of fuel cell modules may be oriented in a same direction. In other cases, at least two of the plurality of fuel cell modules may be oriented in different directions. In any of the embodiments described herein, the plurality of fuel cell modules may be positioned and/or oriented appropriately to maximize volumetric efficiency and minimize a physical footprint of the plurality of fuel cell modules. In any of the embodiments described herein, the plurality of fuel cell modules may be positioned and/or oriented to conform with a size and/or a shape of the vehicle in or on which the fuel cell modules are placed or provided. In any of the embodiments described herein, the plurality of fuel cell modules may be positioned and/or oriented to conform with a size and/or a shape of the vehicle to which the fuel cell modules are coupled or mounted.

[00633] In any of the embodiments described herein, the fuel cell modules may be placed in or on different sides, regions, or sections of a vehicle. The fuel cell modules may be positioned and/or oriented appropriately to maximize volumetric efficiency and minimize a physical footprint of the fuel cell modules. The fuel cell modules may be positioned and/or oriented to conform with a size and/or a shape of the vehicle in or on which the fuel cell modules are placed or provided. The fuel cell modules may be positioned and/or oriented to conform with a size and/or a shape of the vehicle to which the fuel cell modules are coupled or mounted.

Other Embodiments

[00634] Embodiment 1. An anode gas diffusion layer (GDL) for a fuel cell, wherein the fuel cell comprises an electrochemical circuit comprising an anode, a cathode, and an electrolyte between the anode and the cathode, and wherein the anode GDL comprises a porous material comprising one or more properties, wherein the one or more properties comprise a density, a pore size distribution, or particle size distribution, and wherein the one or more properties facilitate transport of hydrogen to the anode, and impede transport of nitrogen or water to the anode.

[00635] Embodiment 2. The anode GDL of Embodiment 1, wherein the porous material is a carbon-based material.

[00636] Embodiment 3. The anode GDL of Embodiment 1, wherein the pore size distribution is configured so that a size of pores of the porous material decreases or increases (1) from a first side of the anode GDL adjacent to outside the fuel cell (2) to a second side of the anode GDL adjacent to the electrolyte.

[00637] Embodiment 4. The anode GDL of Embodiment 1, wherein an ammonia reformer is configured to react ammonia to generate a stream comprising nitrogen and hydrogen, wherein the fuel cell is configured to receive the nitrogen and the hydrogen from the ammonia reformer. [00638] Embodiment 5. A plurality of fuel cell stacks, wherein the plurality of fuel cell stacks are electrically connected in a series arrangement, and wherein a physical property of at least one of the plurality of fuel cell stacks positioned upstream in the series arrangement is different from others of the plurality of fuel cell stacks positioned downstream in the series arrangement, wherein the physical property comprises at least one of: (1) a fuel cell stack volume of each of the plurality of fuel cell stacks, or (2) an anode surface area of fuel cells in each of the plurality of fuel cell stacks.

[00639] Embodiment 6. The plurality of fuel cell stacks of Embodiment 5, further comprising one or more dielectric partitions positioned between at least two of the fuel cell stacks, wherein the dielectric partition is configured to control a local current density between the two fuel cell stacks.

[00640] Embodiment 7. The plurality of fuel cell stacks of Embodiment 5, wherein the plurality of fuel cell stacks is configured to output a power of at least about 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, or 900 kilowatts.

[00641] Embodiment 8. The plurality of fuel cell stacks of Embodiment 5, wherein the plurality of fuel cell stacks is configured to output a power of at most about 900, 800, 700, 600, 500, 400, 300, 200, 100, 90, 80, 70, 60, 50, 40, 30, 20, 10, or 5 kilowatts.

[00642] Embodiment 9. The plurality of fuel cell stacks of Embodiment 5, wherein the current density comprises at least about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 amps per cm2.w

[00643] Embodiment 10. The plurality of fuel cell stacks of Embodiment 5, wherein the current density comprises at most about 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0. lamps per cm2.ww

[00644] Embodiment 11. A cylindrical fuel cell, comprising: an electrochemical circuit comprising a cylindrical anode, a cylindrical cathode, and a cylindrical electrolyte between the cylindrical anode and the cylindrical cathode; wherein the cylindrical anode, the cylindrical cathode, and the cylindrical electrolyte are positioned annularly with respect to a longitudinal axis at a center of the cylindrical fuel cell, wherein the cylindrical anode, the cylindrical cathode, and the cylindrical electrolyte are concentrically aligned with respect to the longitudinal axis; wherein the cylindrical anode is adjacent to an inside surface of the fuel cell; and wherein the cylindrical cathode is adjacent to an outside surface of the fuel cell.

[00645] Embodiment 12. The cylindrical fuel cell of Embodiment 11, wherein the cylindrical anode comprises an anode current collector, an anode gas diffusion layer (GDL) and an anode catalyst.

[00646] Embodiment 13. The cylindrical fuel cell of Embodiment 12, wherein at least one of the anode current collector, the anode gas diffusion layer (GDL), and the anode catalyst comprise a thickness of at least about 0.01 mm to at most about 10 centimeters.

[00647] Embodiment 14. The cylindrical fuel cell of Embodiment 11, wherein the cylindrical anode is positioned at a first radius with respect to the longitudinal axis, wherein the cylindrical electrolyte is positioned at a second radius with respect to the longitudinal axis, wherein the cylindrical cathode is positioned at a third radius with respect to the longitudinal axis, wherein the second radius is greater than the first radius so that the cylindrical electrolyte is positioned farther from the longitudinal axis than the cylindrical anode, and wherein the third radius is greater than the second radius and the first radius, so that the cylindrical cathode is positioned farther from the longitudinal axis than the cylindrical electrolyte and the cylindrical anode.

[00648] Embodiment 15. The cylindrical fuel cell of Embodiment 11, further comprising a cathode feed duct adjacent or at the outside surface of the fuel cell and in fluid communication with the cylindrical cathode, wherein the cathode feed duct is configured to provide at least oxygen to the cylindrical cathode.

[00649] Embodiment 16. The cylindrical fuel cell of Embodiment 11, further comprising an anode feed manifold in fluid communication with the inside surface of the fuel cell and the cylindrical anode, wherein the anode feed manifold is configured to provide a stream comprising at least hydrogen to the cylindrical anode.

[00650] Embodiment 17. The cylindrical fuel cell of Embodiment 16, wherein a mole fraction of the hydrogen in the stream comprises at least about 10, 20, 30, 40, 50, 60, 80, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99%.

[00651] Embodiment 18. The cylindrical fuel cell of Embodiment 16, wherein a mole fraction of the hydrogen in the stream comprises at most about 99, 98, 97, 96, 95, 94, 93, 92, 91, 90, 80, 70, 60, 50, 40, 30, 20 or 10%.

[00652] Embodiment 19. The cylindrical fuel cell of Embodiment 16, wherein the cylindrical fuel cell consumes or utilizes a mole fraction of the hydrogen in the stream of at least about 30, 40, 50, 60, 80, 85, 90, 95, or 99%.

[00653] Embodiment 20. The cylindrical fuel cell of Embodiment 16, wherein the cylindrical fuel cell consumes or utilizes a mole fraction of the hydrogen in the stream of at most about 99, 90, 85, 80, 60, 50, 40, or 30%.

[00654] Embodiment 21. The cylindrical fuel of Embodiment 11, wherein an outer diameter of the cylindrical fuel cell cathode is at least about 1 millimeter, 10 mm, 20 mm, 30 mm, 40 mm, 50 mm, 60 mm, 70 mm, 80 mm, 90 mm, 100 mm, 200 mm, 300 mm, 400 mm, 500 mm, 600 mm, 700 mm, 800 mm, 900 mm, or 1000 mm. [00655] Embodiment 22. The cylindrical fuel cell of Embodiment 11, wherein an outer diameter of the cylindrical fuel cell cathode is at most about 1000 mm, 900 mm, 800 mm, 700 mm, 600 mm, 500 mm, 400 mm, 300 mm, 200 mm, 100 mm, 90 mm, 80 mm, 70 mm, 60 mm, 50 mm, 40 mm, 30 mm, 20 mm, 10 mm, or 1 millimeter.

[00656] Embodiment 23. The cylindrical fuel cell of Embodiment 11, wherein a length of the cylindrical fuel cell is at least about 1 centimeter, 2 cm, 3 cm, 4 cm, 5 cm, 6 cm, 7 cm, 8 cm, 9 cm, 10 cm, 50 cm, 1 m, 5 m, 10 m, 25 m, or 50 meters.

[00657] Embodiment 24. The cylindrical fuel cell of Embodiment 11, wherein a length of the cylindrical fuel cell is at most about 50 meters, 25 m, 10 m, 5 m, 1 m, 50 centimeters, 10 cm, 9 cm, 8 cm, 7 cm, 6 cm, 5 cm, 4 cm, 3 cm, 2 cm, or 1 cm.

[00658] Embodiment 25. A plurality of fuel cells, wherein each of the plurality of fuel cells comprise the cylindrical fuel cell of Embodiment 9.

[00659] Embodiment 26. The plurality of fuel cells of Embodiment 25, wherein the plurality of fuel cells comprises at least about 2, 4, 6, 8, 10, 50, 100, 500, 1000, 5000, or 10,000 fuel cells.

[00660] Embodiment 27. The plurality of fuel cells of Embodiment 25, wherein the plurality of fuel cells comprises at most about 10,000, 5000, 1000, 500, 100, 50, 10, 8, 6, 4, or 2 fuel cells.

[00661] Embodiment 28. The plurality of fuel cells of Embodiment 25, wherein a power output of the plurality of fuel cells is at least about 1 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 80 kW, 90 kW, 100 kW, 500 kW, 1 MW, 5 MW, 10 MW, 20 MW, 30 MW, 40 MW, 50 MW, 60 MW, 70 MW, 80 MW, 90 MW, or 100 MW.

[00662] Embodiment 29. The plurality of fuel cells of Embodiment 25, wherein a power output of the plurality of fuel cells is at most about 100 MW, 90 MW, 80 MW, 70 MW, 60 MW, 50 MW, 40 MW, 30 MW, 20 MW, 10 MW, 5 MW, 1 MW, 500 kW, 100 kW, 90 kW, 80 kW, 60 kW, 50 kW, 40 kW, 30 kW, 20 kW, 10 kW, or 1 kW.

[00663] Embodiment 30. The plurality of fuel cells of Embodiment 25, further comprising one or more skids or plates configured to secure, attach, or affix the plurality of fuel cells thereon.

[00664] Embodiment 31. A method for reforming hydrogen carriers (HCs), comprising: a. heating a first reformer to a first target temperature range; b. directing HC to the first reformer to produce a reformate stream comprising hydrogen; c. combusting the reformate stream to heat a second reformer to a second target temperature range; and d. directing additional HC to the second reformer to produce additional reformate for the reformate stream, wherein a first portion of the reformate stream is combusted to heat the second reformer while HC is being reformed in the second reformer.

[00665] Embodiment 32. The method of Embodiment 31, wherein the first portion of the reformate stream is produced from at least one of the HC or the additional HC.

[00666] Embodiment 33. The method of Embodiment 31, further comprising processing a second portion of the reformate stream in a hydrogen processing module.

[00667] Embodiment 34. The method of Embodiment 33, wherein the hydrogen processing module is a fuel cell.

[00668] Embodiment 35. The method of Embodiment 31, wherein the reformate stream is directed through a hydrogen processing module prior to combusting the first portion of the reformate stream to heat the second reformer.

[00669] Embodiment 36. The method of Embodiment 31, wherein the reformate stream from the first reformer is further reformed in the second reformer.

[00670] Embodiment 37. The method of Embodiment 31, wherein the additional reformate from the second reformer is directed to the first reformer.

[00671] Embodiment 38. The method of Embodiment 37, wherein the additional reformate from the second reformer is further reformed in the first reformer.

[00672] Embodiment 39. The method of Embodiment 31, wherein the additional HC is directed to the first reformer before being directed to the second reformer.

[00673] Embodiment 40. The method of Embodiment 31, wherein a pressure of the reformate stream is reduced when the reformate stream is directed through the hydrogen processing module compared to when the reformate stream is not directed through the hydrogen processing module.

[00674] Embodiment 41. The method of Embodiment 40, wherein a threshold amount of the reformate stream being directed to the hydrogen processing module results in substantially all of the reformate stream passing through the hydrogen processing module.

[00675] Embodiment 42. The method of Embodiment 31, wherein an amount of HC directed to the second reformer is increased over a time period, the time period beginning when the second reformer is heated to the second target temperature range.

[00676] Embodiment 43. The method of Embodiment 31, wherein the amount of HC directed to the second reformer is increased to a first target HC flowrate range.

[00677] Embodiment 44. The method of Embodiment 43, wherein the reformate stream is directed to a hydrogen processing module when the first target HC flowrate range is reached.

[00678] Embodiment 45. The method of Embodiment 44, wherein the HC flowrate is subsequently increased to a second target HC flowrate when the first target HC flowrate is reached.

[00679] Embodiment 46. The method of Embodiment 31, wherein the first portion of the reformate stream is combusted with oxygen, and the oxygen is provided in a substantially constant proportion relative to the hydrogen in the first portion of reformate.

[00680] Embodiment 47. The method of Embodiment 31, further comprising ceasing to perform (a)-(c) after the second reformer reaches the second target temperature range.

[00681] Embodiment 48. The method of Embodiment 31, wherein the first portion of the reformate stream is controlled so that the second reformer maintains a temperature in the second target temperature range.

[00682] Embodiment 49. The method of Embodiment 31, wherein combustion of the reformate stream maintains a temperature in the second reformer within the second target temperature range.

[00683] Embodiment 50. The method of Embodiment 31, wherein the reformate stream is directed to a combustion heater in thermal communication with the second reformer so that the combustion heater receives substantially all of the reformate stream.

[00684] Embodiment 51. The method of Embodiment 50, wherein a second portion of the reformate stream is vented or flared.

[00685] Embodiment 52. The method of Embodiment 50, further comprising increasing an amount of a second portion of the reformate stream that is processed in a hydrogen processing module.

[00686] Embodiment 53. The method of Embodiment 50, further comprising increasing the amount of HC directed to the second reformer to a first target HC flowrate range.

[00687] Embodiment 54. The method of Embodiment 31, wherein the first reactor is electrically heated.

[00688] Embodiment 55. The method of Embodiment 31, wherein the first reactor is heated using combustion of a fuel.

[00689] Embodiment 56. The method of Embodiment 31, wherein the reformate stream is combusted with a stoichiometric excess of oxygen.

[00690] Embodiment 57. The method of Embodiment 56, wherein the oxygen is sourced from air.

[00691] Embodiment 58. The method of Embodiment 31, wherein the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof. [00692] Embodiment 59. The method of Embodiment 31, wherein the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[00693] Embodiment 60. The method of Embodiment 31, wherein the HC comprises at least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof.

[00694] Embodiment 61. A method for reforming HC, comprising: a. directing HC to a reformer at an HC flow rate to produce a reformate stream comprising hydrogen; b. combusting a first portion of the reformate stream with oxygen to heat the reformer; c. processing a second portion of the reformate stream in a hydrogen processing module; and d. based at least in part on a stimulus, performing one or more of: i. changing the HC flow rate; ii. changing a percentage of the reformate stream that is the first portion of the reformate stream; iii. changing a percentage of the reformate stream that is the second portion of the reformate stream; or iv. changing a percentage of the reformate stream that is vented or flared.

[00695] Embodiment 62. The method of Embodiment 61, wherein at least two of (i)-(iv) are performed.

[00696] Embodiment 63. The method of Embodiment 61, wherein all of (i)-(iv) are performed.

[00697] Embodiment 64. The method of Embodiment 61, further comprising changing an oxygen flow rate used for combustion to heat the reformer.

[00698] Embodiment 65. The method of Embodiment 61, wherein the stimulus comprises a change in an amount of the hydrogen used by the hydrogen processing module.

[00699] Embodiment 66. The method of Embodiment 61, wherein the stimulus comprises a temperature of the reformer being outside of a target temperature range.

[00700] Embodiment 67. The method of Embodiment 61, wherein the stimulus comprises a change in an amount or concentration of hydrogen carrier in the reformate stream.

[00701] Embodiment 68. The method of Embodiment 61, wherein one or more of (i)-(iv) are performed so that: x. a temperature of the reformer is within a target temperature range; and y. at most about 10% of the reformate is vented or flared.

[00702] Embodiment 69. The method of Embodiment 68, wherein one or more of (i)-(iv) are achieved for at least 95% of an operational time period.

[00703] Embodiment 70. The method of Embodiment 69, wherein the operational time period is at least about 8 consecutive hours.

[00704] Embodiment 71. The method of Embodiment 61, wherein the stimulus is based at least in part on an increase in an amount of the hydrogen used by the hydrogen processing module.

[00705] Embodiment 72. The method of Embodiment 71, wherein the increased amount of hydrogen is a projected increased amount of hydrogen.

[00706] Embodiment 73. The method of Embodiment 71, wherein, based on the stimulus, one or more of: q. the HC flow rate is increased; r. the percentage of the reformate stream that is the first portion of the reformate stream is decreased; s. the percentage of the reformate stream that is the second portion of the reformate stream is increased; or t. the percentage of the reformate stream that is vented or flared is decreased.

[00707] Embodiment 74. The method of claim 61, wherein the stimulus is based at least in part on a decrease in an amount of the hydrogen used by the hydrogen processing module.

[00708] Embodiment 75. The method of claim 74, wherein the decreased amount of hydrogen is a projected decreased amount of hydrogen.

[00709] Embodiment 76. The method of claim 74, based on the stimulus one or more of: q. the HC flow rate is decreased; r. the percentage of the reformate stream that is the first portion of the reformate stream is increased; s. the percentage of the reformate stream that is the second portion of the reformate stream is decreased; or t. the percentage of the reformate stream that is vented or flared is increased.

[00710] Embodiment 77. The method of Embodiment 61, wherein the stimulus comprises (a) a discontinued processing of hydrogen using the hydrogen processing module or (b) a fault or malfunction of the hydrogen processing module.

[00711] Embodiment 78. The method of Embodiment 61, wherein the hydrogen processing module comprises a plurality of hydrogen processing modules, and the stimulus comprises at least one of (a) a discontinued processing of the hydrogen using one of the plurality of hydrogen processing modules or (b) a fault or malfunction in one of the plurality of hydrogen processing modules.

[00712] Embodiment 79. The method of Embodiment 61, wherein the percentage of the reformate stream that is the second portion of the reformate stream is changed to about zero percent in response to the stimulus.

[00713] Embodiment 80. The method of Embodiment 61, wherein substantially none of the reformate stream is directed to the hydrogen processing module in response to the stimulus.

[00714] Embodiment 81. The method of Embodiment 61, wherein substantially all of the reformate stream is directed to at least one of the second reformer or a combustion heater in thermal communication with the second reformer in response to the stimulus. [00715] Embodiment 82. The method of Embodiments 80-81, wherein a portion of the reformate stream is vented or flared in response to the stimulus.

[00716] Embodiment 83. The method of Embodiment 61, wherein the stimulus is detected using a sensor.

[00717] Embodiment 84. The method of Embodiment 61, wherein the stimulus is communicated to a controller.

[00718] Embodiment 85. The method of Embodiment 61, wherein (d) is performed with the aid of a programmable computer or controller.

[00719] Embodiment 86. The method of Embodiment 61, wherein (d) is performed using a flow control module.

[00720] Embodiment 87. The method of Embodiment 61, wherein the stimulus is a pressure.

[00721] Embodiment 88. The method of Embodiment 87, wherein the pressure is increased in response to decreasing a flowrate to the hydrogen processing module.

[00722] Embodiment 89. The method of Embodiment 87, wherein the pressure is a pressure of the reformate stream.

[00723] Embodiment 90. The method of Embodiment 61, wherein the hydrogen processing module is a fuel cell.

[00724] Embodiment 91. The method of Embodiment 61, wherein the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof.

[00725] Embodiment 92. The method of Embodiment 61, wherein the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[00726] Embodiment 93. The method of Embodiment 61, wherein the HC comprises at least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof.

[00727] Embodiment 94. A method for reforming HC, comprising: a. directing HC to a reformer at an HC flow rate to produce a reformate stream comprising hydrogen; b. combusting a first portion of the reformate stream with oxygen at an oxygen flow rate in a combustion heater to heat the reformer; c. processing a second portion of the reformate stream in a hydrogen processing module; d. measuring a temperature in the reformer or the combustion heater; e. based at least in part on the measured temperature being outside of a target temperature range of the reformer or the combustion heater, performing one or more of: i. changing the HC flow rate; ii. changing the oxygen flow rate; iii. changing a percentage of the reformate stream that is the second portion of the reformate stream; iv. changing a percentage of the reformate stream that is the first portion of the reformate stream; or v. changing a percentage of the reformate stream that is vented or flared out of the combustion heater.

[00728] Embodiment 95. The method of Embodiment 94, wherein the hydrogen processing module is a fuel cell.

[00729] Embodiment 96. The method of Embodiment 94, wherein the reformer comprises an HC reforming catalyst.

[00730] Embodiment 97. The method of Embodiment 94, wherein at least two of (i)-(v) are performed.

[00731] Embodiment 98. The method of Embodiment 94, wherein at least three of (i)-(v) are performed.

[00732] Embodiment 99. The method of Embodiment 94, wherein all of (i)-(v) are performed.

[00733] Embodiment 100. The method of Embodiment 94, wherein the temperature is measured using a temperature sensor.

[00734] Embodiment 101. The method of Embodiment 94, wherein the measured temperature is communicated to a controller.

[00735] Embodiment 102. The method of Embodiment 94, wherein one or more of (i)-(v) are performed with the aid of a controller.

[00736] Embodiment 103. The method of Embodiment 94, wherein at least one of (iii)-(v) are performed using a flow control module.

[00737] Embodiment 104. The method of Embodiment 94, wherein at least one of (iii)-(v) are performed by changing the second portion of reformate processed in the hydrogen processing module.

[00738] Embodiment 105. The method of Embodiment 94, comprising: w based at least in part on the measured temperature being greater than the target temperature range, performing one or more of: q. increasing the HC flow rate; r. decreasing the oxygen flow rate; s. increasing the percentage of the reformate stream that is the second portion of the reformate stream that is processed by the hydrogen processing module; t. decreasing the percentage of the reformate stream that is the first portion of the reformate stream; or u. increasing the percentage of the reformate stream that is vented or flared out of the combustion heater.

[00739] Embodiment 106. The method of Embodiment 105, wherein increasing the percentage of the reformate stream that is the second portion of the reformate stream decreases the first portion of the reformate stream that is combusted.

[00740] Embodiment 107. The method of Embodiment 105, wherein the hydrogen processing module is a fuel cell, and the first portion of the reformate stream is an anode off-gas that is directed from the fuel cell to the combustion heater.

[00741] Embodiment 108. The method of Embodiment 105, wherein decreasing the percentage of the reformate stream that is the first portion comprises decreasing the HC flow rate to the reformer to produce less hydrogen in the reformate stream.

[00742] Embodiment 109. The method of Embodiment 105, wherein the hydrogen processing module is a fuel cell, and increasing the percentage of the second portion of the reformate stream that is processed by the hydrogen processing module increases an amount of power output by the fuel cell.

[00743] Embodiment 110. The method of Embodiment 94, comprising: based at least in part on the measured temperature being less than the target temperature range, performing one or more of q. decreasing the HC flow rate; r. increasing the oxygen flow rate; s. decreasing the percentage of the reformate stream that is the second portion of the reformate stream that is processed by the hydrogen processing module; t. increasing the percentage of the reformate stream that is the first portion of the reformate stream; or u. decreasing the percentage of the reformate stream that is vented or flared out of the combustion heater.

[00744] Embodiment 111. The method of Embodiment 110, wherein decreasing the percentage of the second portion of the reformate stream that is the second portion increases the first portion of the reformate stream that is combusted.

[00745] Embodiment 112. The method of Embodiment 111, wherein the hydrogen processing module is a fuel cell, and the first portion of the reformate stream is an anode off-gas that is directed from the fuel cell to the combustion heater.

[00746] Embodiment 113. The method of Embodiment 110, wherein increasing the percentage of the reformate stream that is the first portion comprises increasing the HC flow rate to the reformer to produce more hydrogen in the reformate stream.

[00747] Embodiment 114. The method of Embodiment 110, wherein the hydrogen processing module is a fuel cell, and decreasing the percentage of the second portion of the reformate stream that is processed by the hydrogen processing module decreases an amount of power output by the fuel cell.

[00748] Embodiment 115. The method of Embodiment 114, further comprising: x. calculating a temperature difference between the temperature measured in the reformer or the combustion heater and a set-point temperature within the target temperature range; and y. changing one or more of (i)-(v) by an amount that is based at least in part on the temperature difference.

[00749] Embodiment 116. The method of Embodiment 115, wherein one or more of (i)- (v) are changed by a proportional factor.

[00750] Embodiment 117. The method of Embodiment 116, wherein the proportional factor is different for each of (i)-(v).

[00751] Embodiment 118. The method of Embodiment 115, further comprising repeating (x) at a subsequent time point to obtain a subsequent temperature difference and repeating (y) to further change one or more of (i)-(v) by an amount that is proportional to the subsequent temperature difference.

[00752] Embodiment 119. The method of Embodiment 118, wherein (x) and (y) are repeated until the measured temperature is within the target temperature range.

[00753] Embodiment 120. The method of Embodiment 94, wherein the temperature measured in the reformer or the combustion heater is a first temperature that is measured at a first time point, the method further comprising: q. at second time point subsequent to the first time point, measuring a second temperature of the reformer or the combustion heater; r. calculating a time period between the first time point and the second time point; s. calculating a temperature difference between the first temperature and the second temperature; and t. changing one or more of (i)-(v) by an amount that is based at least in part on the time period and the temperature difference.

[00754] Embodiment 121. The method of Embodiment 120, further comprising repeating (q)-(t) until the measured temperature is within the target temperature range.

[00755] Embodiment 122. The method of Embodiment 94, wherein the HC comprises at least one of ethane, methane, propane, butane, pentane, hexane, heptane, octane, nonane, decane, a higher alkane, or isomers thereof.

[00756] Embodiment 123. The method of Embodiment 94, wherein the HC comprises at least one of ethanol, methanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, a higher alcohol, or isomers thereof.

[00757] Embodiment 124. The method of Embodiment 94, wherein the HC comprises a least one of cyclohexane, methylcyclohexane, decalin, perhydro-N-ethylcarbazole, perhydrodibenzyltoluene, or isomers thereof.

[00758] While preferred embodiments of the present invention have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. It is not intended that the invention be limited by the specific examples provided within the specification. While the invention has been described with reference to the aforementioned specification, the descriptions and illustrations of the embodiments herein are not meant to be construed in a limiting sense. Numerous variations, changes, and substitutions will now occur to those skilled in the art without departing from the invention. Furthermore, it shall be understood that all aspects of the invention are not limited to the specific depictions, configurations or relative proportions set forth herein which depend upon a variety of conditions and variables. It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is therefore contemplated that the invention shall also cover any such alternatives, modifications, variations or equivalents. It is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.