FIELD OF THE INVENTION

This invention generally relates to hydrogen production, and more particularly to a hydrogen production plant employing intermittent renewable energy (RE) sources combined with energy storage facilities for electrical stabilization and decarbonization of the hydrogen production process.

BACKGROUND OF THE INVENTION

Electrical energy is required for all stages in the hydrogen production and storage process that includes filtration, pumping, desalination, demineralization, electrolysis and compression of the hydrogen product. A general description of a typical hydrogen production plant 10 based on electrolysis process of water is shown in Fig. 1. Such a plant includes a hydrogen production system 3 powered by an electrical power system 1 coupled to an electrical power grid 5. The electrical power system 1 can include one or more renewable or conventional (non-renewable) electrical power units and may also be connected to a wider electricity grid. The hydrogen production system 3 includes a desalination and/or demineralization system 31 whereby water that is sucked in through an inlet port 31a is purified before being sent to an electrolyzer system 32. The level of water purity required depends on the type of electrolyzer system, but usually a reverse osmosis process is used for desalination, which might be followed by an electrodeionization unit for further demineralization. The purified water provided by the desalination/demineralization system 31 is fed to the electrolyzer system 32 that uses the electricity of the electrical power grid 5 to split water into hydrogen and oxygen. The oxygen in this process is generally a waste product that is usually released to the atmosphere via an oxygen outlet port 32b, while the hydrogen produced is transferred to the compressor system 33 for compression. The compressed hydrogen is then transferred to a hydrogen product storage system 34 where it can be stored, or alternatively it can be transported through a pipeline to a consumer. Renewable energy (RE) sources are effectively inexhaustible and are abundantly available throughout the world in various forms, such as natural wind, solar, tidal and wave energy. If the electrical power unit 11 of the electrical power system 1 exclusively employs renewable energy (RE) sources, for example wind turbines, photovoltaic modules, etc., then the plant 10 does not emit any greenhouse gases, and the hydrogen produced by the hydrogen production system 3 qualifies as Green Hydrogen.

Hydrogen production by electrolysis is a highly energy- and water-intensive process. The economic production of Green Hydrogen requires cheap, stable, renewable electricity and high electrolyzer utilization rates. A key challenge of a Renewable Energy- to-Hydrogen configuration rests in the coupling of the intermittent and variable renewable power source to the electrolyzer. The electrical power derived from RE sources is usually highly variable and intermittent. The negative impact of an electrical intermittent power supply on the performance of water electrolyzers is known. For example, A. WeiB et al. in the paper published in J. Electrochemical Soc., 166, F487, 2019 investigated the impact of an intermittent power supply on the performance and lifetime of a proton exchange membrane water electrolyzer, and found that prolonged ‘ Start7‘ Stop’ electrolyzer cycling led to a significant decrease in the performance of the electrolyzer.

If an energy storage unit is electrically connected to a Renewable Energy (RE) generator and a hydrogen production system, then it can absorb the intermittency in the power supply and maximize the utilization rate of the electrolyzer itself. This makes energy storage a key requisite for a cost-effective Green Hydrogen production process. To date, the typical hydrogen production concept has addressed this challenge by using electro-chemical energy storage solutions, such as electrical batteries, in order to stabilize and smoothen the fluctuating power supplied by an RE generator to the water electrolyzer.

For example, WO2010133684A1 describes a hydrogen production system whereby a battery accumulator unit, used for electrical storage, is connected in parallel to a renewable energy generator to stabilize the power supplied to a water electrolyzer. EP2772983A1 describes a similar setup using a battery together with a control system to control electrical flows and thus to reduce rapid variations.

W02020065482A1 describes a hydrogen fueling system, whereby a hydrogen electrolyzer is supplied by an external power source that could be a renewable power source, electrically connected to an electrical storage system that may include at least one of a chemical electric battery, a super capacitor, a pumped hydro system, a compressed gas system, a thermal storage system, a flywheel, or a non-hydrogen fuel cell. Suitable compressed gas systems mentioned include underground compressed air or compressed carbon dioxide systems.

GENERAL DESCRIPTION OF THE INVENTION

The concept of the present invention involves employment of a hydrogen production system in conjunction with a hydro pneumatic energy storage and recovery (HPESR) system that stores energy using pressurized liquid and compressed gas. Integration of an HPESR system with a hydrogen production system powered by RE can stabilize and smoothen the power output of the intermittent renewable energy source that can result in a reduced number of ‘Start7‘Stop’ electrolyzer cycles. This can be reflected in improved electrolyzer lifetime, and thus in a reduced number of electrolyzer replacements over the plant’s lifecycle, while also improving electrolyzer utilization rates.

None of the energy storage systems used in conjunction with a hydrogen production system described in the prior art specifically employs an HPESR system as a means of energy storage. Compared to other storage systems used in the prior art systems, the integration of an HPESR system as an energy storage device within a hydrogen production plant provides several key advantages. Apart from stabilizing and smoothening the power output of the intermittent renewable energy source and mitigating problems originating from intermittency in natural energy sources, the HPESR system can additionally provide pressurized, cool water, which may increase the efficiency of a fully decarbonized hydrogen production process. In operation, pressurized water from the HPESR system can be used as an input to the desalination and/or demineralization system, whereas cool water may be used to enhance the thermal efficiency of the hydrogen compression process that is required for the fuel storage and transport stages.

Furthermore, none of the energy storage systems used in conjunction with a hydrogen production system are designed specifically for offshore use. There are several advantages of locating green hydrogen production offshore. Indeed, there is already a drive towards offshore wind and solar energy production, primarily due to improved resource availability, limited land availability and socio-environmental factors, so it makes sense to co-locate the hydrogen production system offshore. Moreover, the ocean is an abundant source of water that can be desalinated and purified for use in the electrolyzer. Likewise, the maritime industry has the potential to become a major consumer of hydrogen, or of ammonia synthesized from the hydrogen, both of which could replace hydrocarbons as the fuel of choice for ships or other maritime vessels.

In offshore systems, space and weight limitations, as well as increased safety risks on floating or seabed-mounted platforms should be carefully considered. Unlike conventional systems such as batteries, which are bulky and introduce significant risks in a highly volatile, hydrogen-rich environment, the integration of an HPESR system with a hydrogen production system has several advantages. In this case no additional space is required on the offshore platform, since most components or the entire HPESR system can be installed subsea. When compared to batteries, the HPESR system introduces no fire hazard, given that none of the materials used are flammable. Moreover, compared to batteries that have to be replaced every 5 to 7 years, the described approach is designed for a longer lifetime, e.g. in the order of 30 years or more. As noted above, the pressurized sea water from the HPESR system may be used to supply the desalination and/or demineralization system of the hydrogen production system. Furthermore, when the HPESR system is installed offshore, the cold sea water from the HPESR system may be used as a superior heat sink for the hydrogen compression process, thus enabling higher thermal efficiencies. It may also offer the opportunity to reduce the size of heat exchangers required to cool down the hydrogen undergoing compression.

Thus, according to a general aspect of the present invention, there is provided a novel hydrogen production plant. The hydrogen production plant includes an electrical power grid and an electrical power system. The electrical power system includes one or more renewable energy (RE) electrical generation units to supply intermittent renewable electrical power to the electrical power grid. When required, an electrical power system may also include one or more conventional (non-renewable) electrical generation units, and can also be connected to a wider electricity grid.

The hydrogen production plant also includes a hydro-pneumatic energy storage and recovery (HPESR) system configured to mitigate the problems associated with the intermittent supply of natural energy by providing a regulated supply of electrical power to the electrical power grid when required, a hydrogen production system powered by the electrical power from the grid, and a supervisory control and data acquisition (SCAD A) system configured to regulate the supply of electrical power to the grid from the HPESR system in order to stabilize and smoothen the power output of the intermittent renewable energy source.

According to an embodiment of the present invention, the renewable energy (RE) generation unit(s) is(are) configured to harvest one or more renewable energy sources, to generate intermittent electrical power when renewable energy source(s) is(are) available, and to provide the intermittent electrical power Pi to the local electrical power grid.

According to an embodiment of the present invention, the HPESR system includes a pressure containment system having an accumulator chamber configured to hold compressed gas and pressurized water stored in the accumulator chamber under pressure of the compressed gas, and an electrical energy recovery device hydraulically coupled to the accumulator chamber. In operation, potential energy of pressurized water is converted into electricity by allowing the pressurized water to flow through the electrical energy recovery device.

According to an embodiment of the present invention, the electrical energy recovery device includes one or more hydraulic machines, such as hydraulic turbines or hydraulic motors, arranged on an outlet pipeline, which is driven by the pressurized water expelled from the accumulator chamber. An electrical power generator can be coupled to these hydraulic machines. The electrical power generator is configured to convert the rotational mechanical energy of the hydraulic machines into an electrical power output P2, and to provide this electrical power to the electrical power grid when required.

According to an embodiment of the present invention, the HPESR system also includes a hydraulic outlet actuated valve arranged in the outlet pipeline, and configured to regulate egress of the water from the pressure containment system, such that a desired flow rate of the water is maintained through the outlet pipeline.

According to an embodiment of the present invention, the hydrogen production system of the hydrogen production plant is electrically coupled to the electrical power grid for receiving the electrical power Pi (that is provided by the electrical power system) and the electrical power P2 (that is provided by the electrical energy recovery device). For normal operation, the hydrogen production system requires a predetermined electrical power value P3.

According to an embodiment of the present invention, the supervisory control and data acquisition (SCADA) system of the hydrogen production plant is operatively coupled, for example electrically by means of wires or wirelessly, to the hydraulic outlet actuated valve. The SCADA system is configured to control operation of the plant to allow for a controllable supply of the pressurized water to be expelled from the accumulator chamber into the hydraulic machine.

According to an embodiment of the present invention, the SCADA system, inter alia, includes an electric power meter arranged in the electrical power grid and an electronic controller operatively coupled, for example electrically or wirelessly, to the electric power meter. The electric power meter is configured to measure and produce an electrical power data signal representative of the electrical power of the electrical power grid. The electronic controller is responsive to the electrical power data signal and is capable of generating control signals for actuating the hydraulic outlet actuated valve. Specifically, the electronic controller generates control signals to open the hydraulic outlet actuated valve when the intermittent electrical power Pi provided to the electrical power grid by the RE electrical power unit(s) has a magnitude less than the predetermined electrical power value P3, so as to provide a water flow through the outlet pipeline of the HPESR system that is sufficient to generate the electrical power P2 having such an electrical power value that a sum of the intermittent electrical power Pi and the electrical power P2 are greater than or equal to the predetermined electrical power value required by the hydrogen production system P3 (i.e. , Pi + P2 > Ps).

According to an embodiment of the present invention, the HPESR system of the hydrogen production plant includes a water inlet pipeline passing from a water body and hydraulically coupled to the accumulator chamber of the pressure containment system, and a water pressurization system arranged on the water inlet pipeline. The water pressurization system includes a pump drawing electrical power from the electrical power grid when required, configured for pumping a regulated flow of water into the accumulator chamber in order to consume a desired amount of electrical power P4.

According to an embodiment of the present invention, the supervisory control and data acquisition (SCADA) system of the hydrogen production plant includes an electronic controller that is operatively coupled, for example electrically or wirelessly, to the water pressurization system, and is configured to generate control signals for actuating the water pressurization system so that it consumes an amount of electrical power P4. Specifically, the electronic controller generates control signals to actuate the water pressurization system when the intermittent electrical power Pi provided to the electrical power grid by the RE electrical power unit has a magnitude greater than the predetermined electrical power value P3, so as to pump water into the accumulator chamber. The value of P4 is such that a difference of the intermittent electrical power Pi and the electrical power P4 is greater than the predetermined electrical power value required by the hydrogen production system P3 (i.e., Pi - P4 > P3). In other words, the excess power produced by Pi that is not required for operation of the hydrogen production system is used to operate the water pressurization system and hence store this excess energy in the form of compressed air within the HPESR system.

According to an embodiment of the present invention, the SCADA system, inter alia, includes a pneumatic pressure sensor configured for producing a gas pressure sensor signal indicative of a pressure p2 of the compressed gas in the accumulator chamber. The electronic controller is operatively coupled, for example electrically or wirelessly, to the pneumatic pressure sensor, responsive to the gas pressure sensor signal, and is capable of generating control signals for actuating the hydraulic outlet actuated valve. Such signals are intended to open the hydraulic outlet actuated valve when the gas pressure p2 in the accumulator chamber is greater than a minimal allowable pressure p2,min of the compressed gas, and to close the hydraulic outlet actuated valve when the gas pressure p2 is less than a minimal allowable pressure p2,min of the compressed gas. The electronic controller is also capable of generating control signals to allow the pump of the water pressurization system to operate only when the gas pressure p2 in the accumulator chamber is less than the maximum allowable pressure p2,max of the compressed gas, and to turn and maintain the pump off when the gas pressure p2 in the accumulator chamber is greater than or equal to a maximum allowable pressure p2,max of the compressed gas.

According to an embodiment of the present invention, the SCADA system, inter alia, includes an upper water level sensor and a lower water level sensor arranged inside the pressure containment system of the HPESR system. The lower water level sensor is configured for producing a minimal water level signal when the level of the pressurized water in the accumulator chamber is below a minimal water level and the upper water level sensor is configured for producing a maximal water level signal when the level of the pressurized water in the accumulator chamber is above a maximal water level.

According to an embodiment of the present invention, the electronic controller of the SCADA system is operatively coupled, for example electrically or wirelessly, to the water pressurization system, to the upper water level sensor, and to the lower water level sensor. In operation, the electronic controller is responsive to the minimal water level signal and is capable of generating control signals to close the hydraulic outlet actuated valve when the water level in the accumulator chamber is below or equal to the minimal water level. Likewise, the electronic controller is responsive to the maximal water level signal and is capable of generating control signals to turn-off the pump of the water pressurization system when the water level in the accumulator chamber exceeds the maximal water level.

According to an embodiment of the present invention, the hydrogen production system of the hydrogen production plant includes a desalination/demineralization system configured to desalinate and/or demineralize water provided from a water body. The desalination/demineralization system includes a main inlet port through which the water passing from the water body is provided into the desalination/demineralization system. The desalination/demineralization system is electrically coupled to the electrical power grid to receive electrical power for its operation.

According to an embodiment of the present invention, the hydrogen production system also includes an electrolyzer system hydraulically coupled to the desalination/demineralization system for receiving desalinated/demineralized water, and electrically coupled to the electrical power grid for the receiving electrical power for its operation to convert the purified water into hydrogen and oxygen in an electrolysis process.

According to an embodiment of the present invention, the hydrogen production system also includes a hydrogen compressor system (HCS) coupled to the electrolyzer system, and configured for compression of the hydrogen provided by the electrolyzer system. The HCS is electrically coupled to the electrical power grid to receive electrical power for its operation.

According to an embodiment of the present invention, the hydrogen production system also includes a hydrogen storage system (HSS) coupled to the hydrogen compressor system, and configured to store the compressed hydrogen provided by the hydrogen compressor system. The HSS may be electrically coupled to the electrical power grid if it requires electrical power, for example to cool the hydrogen.

According to an embodiment of the present invention, the hydrogen production plant further includes a water supply pipeline coupling the HPESR system to the desalination/demineralization system. The desalination/demineralization system, inter alia, includes a supplementary inlet port configured for providing a portion of the water released from the HPESR system into the desalination/demineralization system via the water supply pipeline. The water supply pipeline is hydraulically connected to the supplementary inlet port at one end of the water supply pipeline and to the outlet pipeline at its other end of the water supply pipeline.

According to an embodiment of the present invention, the hydrogen production plant further includes a flow-regulating valve arranged in the water supply pipeline. The flow-regulating valve is configured to modulate a rate of the water flow passing from the outlet pipeline into the desalination/demineralization system through the supplementary inlet port.

According to an embodiment of the present invention, the hydrogen compressor system (HCS) of the hydrogen production system includes an HCS heat exchanger, a HCS cooling inlet port, and an HCS cooling outlet port configured to provide circulation of a cooling liquid through the HCS heat exchanger for the cooling of the hydrogen compressor system during hydrogen compression.

According to an embodiment of the present invention, the hydrogen storage system (HSS) includes a HSS storage heat exchanger, an HSS storage cooling inlet port, and an HSS storage cooling outlet port configured to provide for circulation of a cooling liquid through the HSS heat exchanger for cooling of the hydrogen storage system during hydrogen storage.

According to an embodiment of the present invention, the hydrogen production plant further includes a cooler hydraulic pipeline coupling the HPESR system to the hydrogen compressor system (HCS) and/or to the hydrogen storage system (HSS) of the hydrogen production system. According to this embodiment, the hydrogen compressor system further includes another HCS cooling inlet port, while the hydrogen storage system includes another HSS cooling inlet port. The cooler hydraulic pipeline is split at one end, and is coupled at this end to the HCS cooling inlet port and to the HSS cooling inlet port, while, at another end, the cooler hydraulic pipeline is coupled to the outlet pipeline coupled to the HPESR system. This provision enables for circulation of a portion of the water released from the HPESR system through the HCS heat exchanger for the cooling of the hydrogen compressor system during hydrogen compression, and through the HSS heat exchanger for cooling of the hydrogen storage system during hydrogen storage. According to an embodiment of the present invention, the hydrogen production plant further includes a flow -regulating valve arranged in the cooler hydraulic pipeline. This flow-regulating valve is configured to modulate the rate of a water flow passing through the cooler hydraulic pipeline from the outlet pipeline into the heat exchangers of the hydrogen compressor system and the hydrogen storage system through their corresponding HCS and HCS inlet ports.

According to an embodiment of the present invention, the hydrogen production plant includes the water supply pipeline coupling the HPESR system to the desalination/demineralization system of the hydrogen production system, and the cooler hydraulic pipeline coupling the HPESR system to the compressor system and/or to the hydrogen storage system of the hydrogen production system.

According to an embodiment of the present invention, the desalination/demineralization system of the hydrogen production system includes a wastewater outlet port. The hydrogen compressor system (HCS) of the hydrogen production system includes an HCS cooling liquid inlet port. The hydrogen storage system (HSS) includes an HSS cooling liquid inlet port. According to this embodiment, the hydrogen production plant further includes a second cooler hydraulic pipeline coupling the wastewater outlet port of the desalination/demineralization system at one end of the pipeline. Another end of the second cooler hydraulic pipeline is split, and is coupled to the HCS cooling inlet port of the hydrogen compressor system to provide for circulation of a cooling liquid through the HCS heat exchanger for cooling of the hydrogen compressor system during hydrogen compression. Another end of the second cooler hydraulic pipeline can also be coupled to the HSS cooling inlet port of the hydrogen storage system to provide circulating of a cooling liquid through the HSS heat exchanger for cooling of the hydrogen storage system during hydrogen storage. Thus, the wastewater exiting from the desalination/demineralization system can be supplied to the compressor system and/or to the hydrogen storage system for cooling thereof.

According to an embodiment of the present invention, the hydrogen production plant further includes a water pressure exchanger hydraulically coupled to the HPESR system and to the hydrogen production system. The water pressure exchanger includes a high pressure inlet port, a low pressure inlet port, a first outlet port, and a second outlet port. According to an embodiment of the present invention, the hydrogen production plant also includes an HPESR supply pipeline coupling said high pressure inlet port to the HPESR system, a pressure exchanger water inlet pipeline coupled to said low pressure inlet port and configured for extraction of water from a water body, a third cooler hydraulic pipeline coupling said first outlet port to the compressor system and/or to the hydrogen storage system, and another water supply pipeline coupling said second outlet port to the desalination/demineralization system through the supplementary inlet port.

According to an embodiment of the present invention, the hydrogen production plant includes a support platform, for example, a fixed or floating support platform. The support platform can, for example, be located in a body of water. The support platform includes a gas chamber having an additional volume for holding a compressed gas. When required, the compressed gas can be at the same pressures as the compressed gas within the pressure containment system of the HPESR system. The hydrogen production plant also includes a pneumatic hose including a pneumatic conduit configured to provide a pneumatic communication for linking the compressed gas in the gas chamber to the compressed gas in the accumulator chamber.

According to some embodiments of the present invention, the electrical power system is mounted on a support platform.

According to some embodiments of the present invention, the hydrogen production system is mounted on a support platform.

There have thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows hereinafter may be better understood. Additional details and advantages of the invention will be set forth in the detailed description, and in part will be appreciated from the description, or may be learned by practice of the invention.

LIST OF REFERENCE NUMERALS AND SYMBOLS

1 - Electrical Power System

10 - Typical Hydrogen Production Plant

11 - Electrical Power Unit

12 - Renewable (RE) Electrical Power Unit

2 - Hydro Pneumatic Energy Storage and Recovery System

20 - Hydrogen Production Plant 21 - Pressure containment system

210 - Accumulator Chamber of Pressure containment system 21

211 - Pressurized Water

212 - Compressed Gas

22 - Inlet Port of the HPESR System 2

221 - Water Pressurization System

222 - Inlet Water Filter

223 - HPESR Water Inlet Pipeline

224 - Inlet of Water Pipeline 223

225 - Water Outlet Pipeline

226 - Outlet Flow Meter

23 - Outlet Port of HPESR system

230 - Flow-Regulating Valve

231 - Outlet Water Filter

232 - Outlet Actuated Valve

233 - Further Flow-Regulating Valve

234 - Another Flow-Regulating Valve

24 - Electrical Energy Recovery Device

241 - Hydraulic Machine

24b - Outlet Port

25 - Outlet Port

251 - Pneumatic Control Valve

26 - Pneumatic Hose

3 - Hydrogen Production (HP) system

31 - Desalination/Demineralization System

31a - Main Inlet Port of Desalination/Demineralization System

31b - Outlet Port of Desalination/Demineralization System

310a - Supplementary Inlet Port of Desalination/Demineralization System

32 - Electrolyzer System

32b - Oxygen Outlet Port of Electrolyzer System

33 - Hydrogen Compressor System

33a - Cooling Inlet Port of Compressor

33b - Cooling Outlet Port of Compressor 33c - HCS Cooling Inlet Port

33d - another HCS Cooling Inlet Port

34 - Hydrogen Storage System (HSS)

34a - HSS Cooling Liquid Inlet Port

34b - HSS Cooling Outlet Port

34c - HSS Cooling Inlet Port

34d - Another HSS Cooling Inlet Port

4 - Supervisory Control and Data Acquisition (SCAD A) System

41 - Electronic Controller

42 - Electric Power Meter

43a - Upper Water Level Sensor

43b - Lower Water Level Sensor

44 - Pneumatic Pressure Sensor

5 - Electrical Power Grid

61 - Water Supply Pipeline

62 - Cooler Hydraulic Pipeline

63 - Second Cooler Hydraulic Pipeline

64 - HPESR supply pipeline

65 - Exchanger Water Inlet Pipeline

66 - Third Cooler Hydraulic Pipeline

67 - Water Supply Pipeline

7 - Pressure Exchanger

701 - Water Feed Pump

71 - High Pressure Inlet Port

72 - Low Pressure Inlet Port

73 - First Outlet Port

74 - Second Outlet Port

8 - Water Body

9 - Support Platform

91 - Gas Chamber

A3 - Water Flow from Water Outlet Pipeline 225 to Desalination/Demineralization System 31 through Supplementary inlet Port 310a A30 Water Flow passing through the Cooler Hydraulic Pipeline 62 from Water Outlet Pipeline 225 into heat exchangers of Hydrogen Compressor System 33 and Hydrogen Storage System 34 through Inlet Ports 33c and 34c, correspondingly

B3 - Water Flow passing through Second Cooler Hydraulic Pipeline 63

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and to see how it may be implemented in practice, embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which:

Fig. 1 illustrates a schematic cross-sectional view of a typical prior art hydrogen production system;

Fig. 2 illustrates a schematic cross-sectional view of a hydrogen production plant, according to one embodiment of the present invention;

Fig. 3 illustrates generally a schematic flowchart diagram of a method for hydrogen production by the hydrogen production plant of Fig. 2, according to an embodiment of the present invention; and

Figs. 4 through 11 illustrate a schematic cross-sectional view of a hydrogen production plant, according to several other embodiments of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The principles and operation of the hydrogen production plant according to the present invention may be better understood with reference to the drawings and the accompanying description. It should be understood that these drawings are presented solely for illustrative purposes and are not meant to be limiting. It should be noted that the figures illustrating various examples of the system of the present invention are not to scale, and are not in proportion, for purposes of clarity. It should be noted that the blocks, as well other elements in these figures, are intended as functional entities only, such that the functional relationships between the entities are shown, rather than any physical connections and/or physical relationships. The same reference numerals and alphabetic characters are utilized for identifying those components which are common in the hydropneumatic energy storage system and its components shown in the drawings throughout the present description of the invention. Examples of constructions are provided for selected elements. Those versed in the art should appreciate that many of the examples provided have suitable alternatives which may be utilized.

Referring to Fig. 2, a schematic cross-sectional view of a hydrogen production plant 20 is illustrated, according to one embodiment of the present invention. The hydrogen production plant 20 includes an electrical power grid 5 and an electrical power system 1 electrically coupled to the electrical power grid 5. The electrical power system 1 includes one or more renewable energy (RE) electrical power units 12. The RE electrical power units 12 are configured to harvest one or more renewable energy sources, generating intermittent electrical power Pi when the renewable energy sources are available. The RE electrical power units 12 can utilize solar and/or wind power, sea waves and water currents as well as tidal flows for generating electrical energy and comprise one or more wind and/or hydraulic machines, a plurality of photovoltaic modules, and other renewable energy technologies, or any combination or number thereof.

The hydrogen production plant 20 also includes a hydro-pneumatic energy storage and recovery (HPESR) system 2 configured to accumulate and store potential energy in compressed gas and pressurized water, and to supply the stored energy to the electrical power grid 5 at demand time periods, i.e., when the intermittent electrical power Pi is not sufficient to operate the hydrogen production plant 20. Thus, the HPESR system 2 allows smoothing out of the operation of the hydrogen production plant 20, and thereby to provide uninterrupted supply of electrical power to the grid 5 during the demand time periods.

According to an embodiment of the present invention, the HPESR system 2 includes a pressure containment system 21 having an accumulator chamber 210 configured to hold compressed gas 212 and pressurized water 211 stored in the accumulator chamber 210 under pressure of the compressed gas. The term "pressure containment system" is broadly used to describe any one or more containers, vessels, tanks, pipelines, wells, caverns, subterranean voids, or other enclosed volumes, that can be used for holding compressed fluid (gas and liquid) at a desired pressure.

It should be understood that generally, the pressure containment system 21 can have any desired shape and be constructed of a suitable material, such as metal, plastic or composite material, with wall thickness appropriate to withstand the strain caused by the gas-hydraulic pressure inside the accumulator chamber 210. The pressure containment system can also include a rock formation, such as a cavern, well, or subterranean void, or an enclosed volume that can contain the compressed fluid.

Although one pressure containment system 21 is shown in Fig. 2, generally, the hydrogen production plant 20 can utilize any desired number of pressure containment systems 21 (not shown) with the accumulator chamber/s 210 interconnected to each other through corresponding pipelines. In this provision, all the accumulator chambers 210 are interlinked, thereby forming a common volume.

According to an embodiment of the present invention, the pressure containment system 21 includes a pneumatic control valve 251 installed in an outlet port 25 pneumatically connected to the accumulator chamber 210, and configured to enable the HPESR system 2 to be filled with a gas. Examples of gases suitable for the present invention include, but are not limited to, air, nitrogen and carbon dioxide. It should be noted that carbon dioxide can experience a phase change from gas to liquid at the upper operating pressure of the accumulator chamber 210, which would correspond to the vapor pressure of the gas.

The accumulator chamber 210 of the pressure containment system 21 can be precharged prior to operation of the HPESR system 2 with a gas using one or more pneumatic compressors (not shown) that can be either a part of the sub-system or located on removable infrastructure (not shown). The accumulator chamber 210 can also be recharged to replace any gas that can be lost through operation of the HPESR system 2 by increasing the amount of gas 212 that it contains, until it reaches the desired pre-charge minimal storage pressure p2,min- The gas-hydraulic pressure within the accumulator chamber 210 should be sufficient to provide water to various hydraulic electricity generators, cooling systems, and to other points where the water can be utilized.

The pneumatic control valve 251 can, for example, be located in an area of the pressure containment system 21 where it is easily accessible. When required, the pressure containment system 21 can also include one or more safety valves (not shown) that can automatically open when pressure in the accumulator chamber 210 exceeds a certain level for safety reasons.

According to an embodiment of the present invention, the HPESR system 2 includes an HPESR water inlet pipeline 223 passing from a water body, such as a lake, sea, etc., to the accumulator chamber 210. The HPESR water inlet pipeline 223 is hydraulically coupled to an inlet port 22 of the pressure containment system 21. When desired, the inlet end 224 of the HPESR water inlet pipeline 223 may extend to deeper waters that are colder than water in shallow water or close to the surface.

According to an embodiment, the HPESR system 2 includes a water outlet pipeline 225 coupled to an outlet port 23 at the pressure containment system 21. The water outlet pipeline 225 is equipped with an outlet actuated valve 232 arranged in the water outlet pipeline 225. The outlet actuated valve 232 is configured to regulate the water flow from the pressure containment system 21 such that a desired flow rate of egress of the water is maintained over specified periods of time through the water outlet pipeline 225. The term “actuated valve” as used herein has a broad meaning, and relates to any electromechanical device adapted to controllably regulate the flow rate of fluid.

According to an embodiment of the present invention, the HPESR system 2 also includes an electrical energy recovery device 24 hydraulically coupled to the accumulator chamber 210 of the accumulator chamber 210 via the water outlet pipeline 225.

The electrical energy recovery device 24 includes a hydraulic machine 241, such as hydraulic turbines or hydraulic motors, that can be driven by the pressurized water expelled from the accumulator chamber 210, and an electrical power generator (not shown) electrically coupled to the electrical power grid 5.

In operation, the water transferred through the water outlet pipeline 225 is controllably supplied to the hydraulic machine 241 that is mechanically coupled to an electrical generator for generating electricity. The water flow rate of the water transferred through the water outlet pipeline 225 is controlled by the outlet actuated valve 232. The water supplied to the hydraulic machine 241 is ejected through an outlet port 24b.

The electrical power generator is configured to convert the rotational mechanical energy of the hydraulic machine 241 into electrical power P2. In demand time periods, when the intermittent electrical power Pi generated by the electrical power sub-system 1 has a magnitude less than a predetermined electrical power value P3 required for the normal operation of the hydrogen production plant 20, the pressurized water is released from the accumulator chamber 210 and is projected onto the hydraulic machine 241. The electrical power P2 generated by electrical power generator is provided to the electrical power grid 5. In order to provide an uninterrupted supply of electrical power to the grid 5 during demand time periods, the electrical power P2 together with the intermittent electrical power Pi should be greater than or equal to the predetermined electrical power P3 required for normal operation of the hydrogen production plant 20. According to an embodiment of the present invention, the electrical power system 1 additionally includes one or more non-renewable electrical power units (not shown). Moreover, the electrical power system 1 can also be connected to a wider (external) electricity grid. Thus, when the intermittent electrical power/*/ is not available and/or not sufficient, then a required electrical power for operation of the hydrogen production plant 20 can be generated by the additional non-renewable electrical power units. Moreover, when the storage HPESR system 2 is in a fully-discharged state, such that electrical P3 that is required for the normal operation of the hydrogen production plant 20 is not available, then power sources from connections to the wider electricity grid can be used.

It should be noted that after passing the hydraulic machine 241, the ejected water may still be used for cooling purposes as long as the exit pressure is high enough to allow the flow of the water across the pipeline up to the point where such cooling is required.

According to an embodiment of the present invention, the HPESR system 2 also includes a water pressurization system 221 including one or more pumps configured for pumping water into the accumulator chamber 210. In the accumulator chamber 210, the water is pressurized, thereby also compressing the gas. The pressurized water 211 is stored at high pressure in the accumulator chamber 210. The water pressurization system 221 is hydraulically coupled to an inlet port 22 of the pressure containment system 21 through the HPESR water inlet pipeline 223.

According to an embodiment of the present invention, the HPESR system 2 also includes an inlet water filter 222 arranged in the HPESR water inlet pipeline 223 upstream of the water pressurization system 221, since water filtration may be required to remove particulate matter that may clog up and contaminate the accumulator chamber 210. When desired, the HPESR system 2 also includes an outlet water filter 231 arranged in the water outlet pipeline 225 downstream of the pressure containment system 21 between the outlet port 23 and the electrical energy recovery device 24, since filtration may be required to remove particulates originating from the pressure containment system 21 itself.

According to an embodiment of the present invention, the hydrogen production plant 20 includes a hydrogen production system 3 electrically coupled to the electrical power grid 5 for receiving the electrical power Pi provided by the electrical power system 1 and the electrical power P2 provided by the electrical energy recovery device 24. The hydrogen production plant 20 can be scaled to meet a variety of input and output ranges ranging in size from small industrial plants installed in shipping containers, to large-scale centralized production facilities that can deliver the hydrogen by trucks, or be connected to pipelines.

According to an embodiment of the present invention, the hydrogen production system 3 includes a desalination/demineralization system 31 where water provided from a water body (not shown), such as a lake, sea, etc., is purified. It should be understood that desalination and demineralization of the water is required when seawater is used. In turn, demineralization can be employed alone if fresh water is used. The desalination/demineralization system 31 includes a main inlet port 31a through which water passing from the water body is provided into the system 31. The desalination/demineralization system 31 also includes a purified water outlet port, and a wastewater outlet port 31b through which brine or wastewater is expelled.

The hydrogen production system 3 also includes an electrolyzer system 32 which is hydraulically coupled to the desalination/demineralization system 31 for receiving the purified water, and to the electrical power grid 5 for receiving electrical power sufficient to break down the purified water into hydrogen and oxygen in an electrolysis process.

Through the electrolysis process, the electrolyzer system 32 creates hydrogen gas that can either be stored as a compressed gas, or liquefied. The oxygen that is left over is released into the atmosphere via an oxygen outlet port 32b or can be captured or stored to supply other industrial processes and/or medical gases, if and when desired.

According to an embodiment of the present invention, the hydrogen production system 3 includes a hydrogen compressor system (HCS) 33 coupled to the electrolyzer system 32 for hydrogen compression, e.g., by using an ionic compressor.

It should be noted that, when required, the hydrogen compressor system 33 can include an HCS heat exchanger (not shown), an HCS cooling liquid inlet port 33a, and an HCS cooling outlet port 33b to provide for circulation of a cooling liquid (e.g., water) through the heat exchanger for cooling of the hydrogen compressor system 33 during compression.

According to an embodiment of the present invention, the hydrogen product may then be stored in a hydrogen storage system (HSS) 34 coupled to the hydrogen compressor system 33. The hydrogen storage system 34 can include one or more pressure vessels (not shown) or one or more pipelines (not shown) giving the capability also to transfer the hydrogen to vessel(s) or to transport it to shore, when the hydrogen production system 3 is installed in an aquatic environment, e.g., at sea.

It should be noted that when required, the hydrogen storage system 34 can include a corresponding HSS heat exchanger (not shown), an HSS cooling liquid inlet port 34a, and an HSS cooling outlet port 34b to provide for circulation of a cooling liquid (e.g. water) through the heat exchanger for cooling of the hydrogen storage system 34.

The corresponding electrical power components of the electrical power required for their operation by the desalination/demineralization system 31, the electrolyzer system 32, the hydrogen compressor system 33, and the hydrogen storage system 34, are electrical power components P31, P32, P33 and P34, correspondingly. It should be noted that the value of P34 may be zero if the hydrogen storage system does not require electric power for its operation.

According to an embodiment of the present invention, the predetermined electrical power P3 required for normal operation of the hydrogen production system 3 is a sum of P31, P32, P33 and P34, to wit: P3 = P31 + P32 + P33 + P34.

According to an embodiment of the present invention, the hydrogen production plant 20 includes a supervisory control and data acquisition (SCAD A) system indicated by a reference numeral 4. The SCADA system 4 is a computer controlled system distributed throughout the hydrogen production plant 20. Generally, the SCADA system 4 may include, without limitations, flow meters, sensors, actuators, monitoring devices, as well as other similar or suitable devices. Each device may be a commercially available component.

In particular, sensors are required at strategic points of the plant 20 such as, for example, on the electrical power system 1, on the HPESR system 2, on the hydrogen production system 3, etc. During the operation of the plant 20, the electrical power output from the electrical power system 1 and from the electrical energy recovery device 24 can be metered to manage the electrical power provided to different systems.

Regarding the HPESR system 2, acquisition of pressure, and possibly also temperature and water levels, can be necessary to determine its state-of-charge. Thus, a combination of pressure, temperature, and liquid level sensors, and/or other sensors can be arranged at strategic points to measure any other parameters required to monitor the status of the fluids within the pressure containment system 21. The sensors can, in turn, provide the necessary information to allow controlled operation of the inlet water filter 222, the outlet water filter 231, the water pressurization system 221 for pumping water into the accumulator chamber 210, and the hydraulic outlet actuated valve 232, etc.

Regarding the hydrogen production system 3, sensors can be required to monitor the flow and temperature of the hydrogen within the compressor system 33 and in the hydrogen storage system 34. These parameters can be used for determining the heat that is generated during hydrogen production, and establishing the cooling loads required for these systems, so as to determine whether the HPESR system 2 can supply the required cooling.

The SCADA system 4 also includes an electronic controller 41 programmed with a software model stored in a computer-readable medium (not shown), and configured for controlling the operation of the hydrogen production plant 20. The electronic controller 41 of the SCADA system 4 can, for example, be installed at the hydrogen production system 3. Alternatively, when desired, the electronic controller of the control system can be installed at the HPESR system 2. Likewise, the electronic controller 41 of the SCADA system 4 can be arranged at some intermediate position in the plant 20.

According to an embodiment of the present invention, the SCADA system 4 includes an electric power meter 42 arranged in the electrical power grid 5 and configured to measure and produce an electrical power data signal representative of the electrical power being supplied by the electrical power system 1 to the electrical power grid 5. The electronic controller 41 is operatively coupled, for example electrically or wirelessly, inter alia, to the electric power meter 42 and to the hydraulic outlet actuated valve 232, and is configured to control operation of the hydraulic outlet actuated valve 232 for a controllable supply of pressurized water expelled from the accumulator chamber into the hydraulic machine 24.

The electronic controller 41 is responsive to the electrical power data signal generated by the electric power meter 42, and is capable of generating control signals for actuating the hydraulic outlet actuated valve 232 to open said hydraulic outlet actuated valve 232, when the intermittent electrical power Pi provided to the electrical power grid 5 from the electrical power system 1 has a magnitude less than a predetermined electrical power value P3. The predetermined electrical power value P3 is the value required for the normal operation of the hydrogen production system 3. When the hydraulic actuated valve 232 is actuated, it can provide a water flow through the water outlet pipeline 225 sufficient to generate the electrical power P2, having such an electrical power value that a sum of the electrical power P2 and the intermittent electrical power Pi is greater than or equal to said predetermined electrical power value P3. For measuring pressure of the gas within the pressure containment system 21, the SCADA system 4 includes a pneumatic pressure sensor 44 that can be operable for producing a gas pressure sensor signal p2 of the gas 212 throughout operation of the HPESR system 2. Likewise, the SCADA system 4 can include one or more hydraulic pressure sensors (not shown) that can be operable for producing hydraulic pressure sensor signals throughout operation of the system. Location of the pneumatic and hydraulic pressure sensors depends on the specific configuration of the system. For example, the pneumatic pressure sensor 44 can be arranged within the accumulator chamber 210. In turn, the hydraulic pressure sensors can be arranged within the HPESR water inlet pipeline 223 to measure a pressure of the ingress water flow within the HPESR inlet water pipeline 223, and to measure a pressure of the egress water flow within the water outlet pipeline 225. When required, the SCADA system 4 can alert the operator of any detrimental pressure drops. The gas and hydraulic pressure sensor signals can be relayed to the electronic controller 41 via a connecting wire, or wirelessly.

According to some embodiments, the SCADA system 4 includes an upper water level sensor 43a and a lower water level sensor 43b arranged inside the pressure containment system 21. The upper water level sensor 43a and the lower water level sensor 43b are configured for producing minimal and maximal water level signals, correspondingly, to ensure that the level of the water inside the pressure containment system 21 is within a predetermined level limit range.

To provide regulation of the water flow rate, the SCADA system 4 of the hydrogen production plant 20 can include one or more flow meters (not shown) arranged within the HPESR water inlet pipeline 223 and within the water outlet pipeline 225. The flow meters are configured for producing water flow sensor signals representative of the water ingress flow within the HPESR water inlet pipeline 223 and the water egress flow within the water outlet pipeline 225, for example by means of an outlet flow meter 226, correspondingly.

According to an embodiment of the present invention, the electronic controller 41 is operatively coupled, for example electrically or wirelessly, to the pneumatic pressure sensors, the hydraulic pressure sensor, water level sensors, and to the flow meters for controllable pumping of the water to the pressure containment system 21 and for controllable discharge of the water from the accumulator chamber 210. The electronic controller 41 is, inter alia, responsive to the gas pressure sensor signals, the hydraulic pressure sensor signals, the minimal and maximal water level signals, and the water flow sensor signals, respectively. The electronic controller 41 is capable of generating control signals to control operation of the pneumatic control valve 251 if this is electrically controlled. The location of flow meters along the HPESR water inlet pipeline 223 and on the water outlet pipeline 225 depends on the specific system configuration.

In particular, when a level of the pressurized water 211 drops lower than the lower level limit, the electronic controller 41 generates a lower level control signal in order to close the outlet actuated valve 232. This enables avoiding compressed gas from being lost and having the pressure containment system 21 de-pressurized. Likewise, when the water level exceeds an upper level limit, the electronic controller 41 generates an upper level control signal to open the actuated valve 232, so as to decrease the water level to a desired value.

The discharge flow of the water within the water outlet pipeline 225 can be measured by an outlet flow meter 226 arranged in the water outlet pipeline 225. The outlet flow meter 226 is operable for producing an outlet water flow sensor signal. The outlet flow meter 226 is operatively coupled, for example electrically or wirelessly, to the electronic controller 41, which is, inter alia, responsive to the outlet water flow sensor signal and capable of generating a valve control signal for controlling the operation of the outlet actuated valve 232. Depending on the electric power attributes of the hydrogen production plant 20, a desired egress flow rate from the system can be specified and maintained by the electronic controller 41 during operation of the system 2. The outlet actuated valve 232, inter alia, ensures a supply of pressurized water to produce an electrical power output and feed the generated electricity to the grid 5 over demand time periods when the intermittent electrical power Pi provided by the electrical power system 1 is not sufficient to operate the hydrogen production plant 20.

According to some embodiments of the present invention, the electronic controller 41 is also operatively coupled, for example electrically or wirelessly, to the water pressurization system 221 for controllable pumping of water into the accumulator chamber 210. In particular, when the water level drops lower than the lower level limit, in response to the minimal water level signal of the lower water level sensor 43b, the electronic controller 41 generates a control signal to close the hydraulic outlet activated valve 232 and/or turn-on the pump of the water pressurization system 221 to start pumping water into the accumulator chamber 210. On the other hand, when the water level in the accumulator chamber 210 exceeds an upper level limit, in response to the maximal level signal of the upper level sensor 43a, the electronic controller 41 generates a control signal to open the outlet actuated valve 232 and/or turn-off the pump of the water pressurization system 221 to stop pumping water into the accumulator chamber 210, so as to decrease the water level to a desired value.

Fig. 3 illustrates a schematic simplified flowchart diagram of a method for hydrogen generation by the hydrogen production plant 20, according to an embodiment of the present invention. Referring to Fig. 2 and Fig. 3 together, as indicated in block 301, the method includes measuring by means of the electric power meter 42, and providing to the electrical controller 41 information on the intermittent electrical power Pi generated by the electrical power system 1. The method also includes a value of the predetermined electrical power value P3 required for normal operation of the hydrogen production system 3 and provides this value to the electrical controller 41. Likewise, the method also includes measuring by means of the pneumatic pressure sensor 44 and providing to the electrical controller 41 the current gas pressure sensor signal indicative of pressure p , and setting the minimal pi, min and maximal allowable pressure pi, max of the compressed gas 212 in the accumulator chamber 210 of the pressure containment system 21. According to an embodiment of the present invention, the method includes setting magnitudes for the minimal allowable water level L _m in and the maximal allowable water level Lmax of the pressurized water 211 in the accumulator chamber 210 and providing these values to the electrical controller 41. Reaching the values L _m in and Lmax in the accumulator chamber 210 is measured by the lower and upper water level sensors 43b and 43a, correspondingly.

According to an embodiment of the present invention, the electrical controller 41 determines (block 302) whether the intermittent electrical power Pi from the electrical power system 1 is greater than, equal to or less than the predetermined electrical power value P3.

When the intermittent electrical power Pi from the electrical power system 1 is less than the predetermined electrical power value P3, (e.g., renewable energy source(s) are limited in power, or not available), the needed electrical power may be supplied by the HPESR system 2 to power the hydrogen production system 3 for as long as the HPESR system 2 retains a sufficient charge. Supply of electrical power by the HPESR system 2 is carried out in the discharging cycle, when the pressurized water 211 stored within the accumulator chamber 210 of the pressure containment system 21 is pushed out by the compressed gas 212. The HPESR system 2 reaches its fully-discharged state when the lowest allowable level of the water 211 is attained within the accumulator chamber 210. At this point, the water reaches its minimum level, while the gas pressure drops to a pressure value close to the minimal pressure p2.min-

Accordingly, when the intermittent electrical power Pi from the electrical power system 1 is less than the predetermined electrical power value P3, the electrical controller 41 generates the corresponding control signal to actuate the hydraulic outlet actuated valve 232 to turn it “on”.

According to the embodiment shown in Fig. 3, the turning of the hydraulic outlet actuated valve 232 “on” can also be conditioned by the current values of the gas pressure P2 and/or the level of the pressurized water in the accumulator chamber 210. Thus, generating the corresponding control signal by the electronic controller 41 to actuate the hydraulic outlet actuated valve 232 to turn it “on” can be carried out when the current gas pressure p2 in the accumulator chamber 210 is greater (block 303) than the minimal allowable pressure p2,min of the compressed gas 212, and/or when the minimal water level of the pressurized water 211 in the accumulator chamber 210 is not reached.

When the hydraulic actuated valve 232 is actuated, it can provide a water flow through the water outlet pipeline 225 that can be projected onto the electrical energy recovery device 24. The hydraulic power of the water can be sufficient to generate (block 304) the electrical power P2 being greater than or equal to the predetermined electrical power value P3. The electric power P2 provided by the electrical energy recovery device 24 can be supplied to the hydrogen production system 3 in the required amount.

It should be noted that the hydraulic actuated valve 232 and the electrical energy recovery device 24 remain in the “off’ position (block 305) if the current gas pressure p2 in the accumulator chamber 210 is less than the minimal allowable pressure p2,min of the gas 212, and/or a water level L in the accumulator chamber 210 is less than the minimal water level L _m in of the pressurized water 211 in the accumulator chamber 210.

According to an embodiment of the present invention, the electronic controller 41, responsive to the gas pressure sensor signal, generates control signals for actuating said hydraulic outlet actuated valve 232. The control signals can be indicative of instructions to open to hydraulic outlet actuated valve 232 when the gas pressure pi in the accumulator chamber 210 is greater than a minimal allowable pressure p2,min of the compressed gas 212 and the intermittent electrical power Pi is less than or equal to the predetermined electrical power value P3.

The control signals can also be indicative of instructions to maintain the hydraulic outlet actuated valve 232 closed when the intermittent electrical power Pi is greater than the predetermined electrical power value P3 for any value of the gas pressure pi in the accumulator chamber 210. The control signals can also be indicative of instructions to close the hydraulic outlet actuated valve 232 in order to prevent egress of the water from the pressure containment system 21 when the gas pressure p2 in the accumulator chamber 210 is less than or equal to a minimal allowable pressure p2,min of the compressed gas 212.

When at least one renewable energy source is available to any of the RE electrical power units 12, the electrical power system 1 can produce a varying amount of intermittent electrical power Pi. If this electrical power is equal to or greater than the power P3 required to operate the hydrogen production system 3, i.e. Pi > P3. the electrical power Pi produced by the electrical power system 1 may be used to electrify the hydrogen production system 3.

When the intermittent electrical power Pi from the electrical power system 1 is equal to or greater than the predetermined electrical power value P3 (block 302), the hydraulic actuated valve 232 and the electrical energy recovery device 24 of the HPESR system 2 can remain in the “off’ position, while the electrical controller 41 generates a control signal to close the hydraulic outlet activated valve 232 (if it was opened), and to turn the pump (block 306) of the water pressurization system 221 on to start pumping water into the accumulator chamber 210. It should be understood that pumping water into the accumulator chamber 210 is allowed only in cases where the current gas pressure p2 in the accumulator chamber 210 is less (block 307) than the maximal allowable pressure P2,max of the gas 212 in the accumulator chamber 210 (i.e. pi < pi.max). and/or if the maximal water level L, _ma x of the pressurized water 211 in the accumulator chamber 210 is not reached (i.e. L < L, _m ax). In turn, if the current gas pressure p2 in the accumulator chamber 210 is greater (block 307) than the maximal allowable pressure p2,max of the gas 212 in the accumulator chamber 210, (i.e. p2 > p2,max) and/or if the maximal water level of the pressurized water 211 in the accumulator chamber 210 is reached (i.e., L > L, _m ax). the pump of the water pressurization system 221 is turned off (block 308). When the power Pi supplied by the electrical power system 1 is in excess of the requirements of the hydrogen production system 3, i.e. P> > 3, the excess power can also be used for charging of the HPESR system 2. In particular, if required, the power supplied to the HPESR system 2 can be used for operating the water pressurization system 221 configured to suck water from the water body through inlet port 22 via the HPESR water inlet pipeline 223, and to compress the water into the accumulator chamber 210 of the pressure containment system 21.

Thus, according to an embodiment of the present invention, the electronic controller 41 is configured to generate control signals for actuating the water pressurization system 221 when the intermittent electrical power Pi provided to the electrical power grid 5 has a magnitude greater than the predetermined electrical power value P3 so as to consume an amount of electrical power P4 being such that a subtraction of the electrical power P4 from the intermittent electrical power Pi is greater than the predetermined electrical power value P3 (i.e., Pi - P4 > P3). In other words, the excess power produced by Pi that is not required for operation of the hydrogen production system is used to operate the water pressurization system and hence store this excess energy in the form of compressed air within the HPESR system.

According to an embodiment of the present invention, the electronic controller 41, responsive to the gas pressure sensor signal, can generates control signals for actuating the water pressurization system 221 to turn on or off the pump of the water pressurization system 221. Specifically, the pump is turned on when the gas pressure p2 in the accumulator chamber 210 is less than a maximum allowable pressure p2,max of the compressed gas 212 and the intermittent electrical power Pi is greater than the predetermined electrical power value P3. However, the pump can be maintained in the "off" state when intermittent electrical power Pi is less than or equal to the predetermined electrical power value P3 for any value of the gas pressure pi- Moreover, responsive to the gas pressure sensor signal, the electronic controller 41 generates control signals for actuating the water pressurization system 221 to turn the pump off, in order to prevent further entering water into the pressure containment system 21, when the gas pressure p2 in the accumulator chamber 210 is greater than a maximum allowable pressure p2,max of the compressed gas 212.

In operation, the level L of the water 211 within the accumulator chamber 210 rises. The rising water compresses the gas 212 until either the maximum allowable pressure, ? , max or the maximal allowable water level Lmax of the water in the accumulator chamber 210 (measured by the upper water level sensor 43a), is reached.

In this mode of operation, the outlet actuated valve 232 remains closed and the HPESR system 2 is said to be in ‘charging mode’. The HPESR system 2 will be in its fully-charged state when the maximum allowable pressure limit, p2,max, and/or the maximum allowable water level Lmax are/is reached in the accumulator chamber 210 of the pressure containment system 21.

Turning now to Figs. 4 through 11, various types of configuration of the hydrogen production plant are described hereinbelow, according to various other embodiments of the present invention. It should be noted that not all components of the hydrogen production plant are shown and/or indicated in these figures, but mainly those which are necessary for description of the operation of the hydrogen production system 3.

Fig. 4 shows a schematic cross-sectional view of a hydrogen production plant 400 according to some embodiments of the present invention. This embodiment of the hydrogen production plant 400 differs from the embodiment of the plant 20 shown in Fig. 2 by the fact that it further includes a water supply pipeline 61 coupling the HPESR system 2 to the desalination/demineralization system 31 of the hydrogen production system 3.

According to this embodiment, the desalination/demineralization system 31 of the hydrogen production system 3 includes a supplementary inlet port 310a through which a portion of the water released from the HPESR system 2 can be provided into the desalination/demineralization system 31 via the water supply pipeline 61. The water supply pipeline 61 is coupled to the supplementary inlet port 310a and to the water outlet pipeline 225 of the pressure containment system 21 at its other end. The hydraulic supply flow through the supplementary inlet port 310a into the desalination/demineralization units 31 is depicted as A3.

According to an embodiment of the present invention, the hydrogen production plant 400 further includes a flow-regulating valve 230 arranged in the water supply pipeline 61. The flow-regulating valve 230 is operatively coupled, for example electrically or wirelessly, to the electronic controller 41, and is configured to modulate a rate of the water flow A3 passing from the water outlet pipeline 225 into the desalination/demineralization system 31 through the supplementary inlet port 310a. Thus, in addition to electricity supply to the hydrogen production system 3, the HPESR system 2 can also supply pressurized water stored in the accumulator chamber 210 to the desalination/demineralization system 31.

It should be understood that the water passing from the HPESR system 2 can be used only as a sole water supply into the system 31. In this case, the plant configuration shown in Fig. 4 can cut down on the infrastructure necessary to independently pump water into the desalination/demineralization system 31, and thus reduce the associated electrical consumption, as well as operations, maintenance and replacement costs. However, when required, the amount of pressurized water may be augmented by also extracting water from a nearby or surrounding water body through the main inlet port 31a.

Fig. 5 shows a schematic cross-sectional view of a hydrogen production plant 500, according to a further embodiment of the present invention. This embodiment of the hydrogen production plant 500 differs from the embodiment shown in Fig. 2 by the fact that it further includes a cooler hydraulic pipeline 62 coupling the HPESR system 2 to the hydrogen compressor system 33 and/or to the hydrogen storage system 34 of the hydrogen production system 3. For example, in a marine environment, cool, deep seawater stored in the HPESR system 2 may be used for the cooling of hydrogen compression and storage processes. Thus, in addition to a supply of electricity to the hydrogen production system 3, this configuration also offers the possibility of supplying pressurized cool water from the HPESR system 2 for cooling the hydrogen compressor system 33 and/or to the hydrogen storage system 34.

According to this embodiment of the present invention, the hydrogen compressor system (HCS) 33 includes an HCS heat exchanger (not shown) and another HCS cooling inlet port 33c to provide circulation of a portion of the water released from the HPESR system 2 through the heat exchanger for cooling of the hydrogen compressor system 33 during compression. Likewise, the hydrogen storage system (HSS) 34 includes a HSS heat exchanger (not shown) and another HSS cooling inlet port 34c to provide circulation of a portion of the water released from the HPESR system 2 through the corresponding heat exchanger for cooling of the hydrogen storage system 34. It should be noted that the HCS heat exchanger and the HSS heat exchanger can be external and/or internal heat exchangers. The cooling water is expelled from the cooling outlet ports 33b and 34b of the hydrogen compressor system 33 and the hydrogen storage system 34, correspondingly. The cooler hydraulic pipeline 62 is split at one end and is coupled to the HCS cooling inlet port 33c and to the HSS’s cooling inlet port 34c. At another end, the cooler hydraulic pipeline 62 is coupled to the water outlet pipeline 225. The hydraulic supply flow through the cooler hydraulic pipeline 62 is depicted as A30.

According to an embodiment of the present invention, the hydrogen production plant 500 further includes a further flow-regulating valve 233 arranged in the cooler hydraulic pipeline 62. The flow-regulating valve 233 is configured to modulate the rate of the water flow A30 passing through the cooler hydraulic pipeline 62 from the water outlet pipeline 225 into the heat exchangers of the hydrogen compressor system 33 and the hydrogen storage system 34 through the inlet ports 33c and 34c, correspondingly.

It should be noted that the water that is supplied from the HPESR system 2 cooling the heat exchangers allows cutting down on the cooling load required for the heatgenerating compression and storage processes. It should also be noted that although the cooler hydraulic pipeline 62, as shown in Fig. 5, is coupled to the HCS cooling inlet port 33c and to the HSS cooling inlet port 34c, if additional cooling is required, then additional cooling water can still be fed, mutatis mutandis, through the HCS inlet port 33a and the HSS’s inlet port 34a of the hydrogen compressor system 33 and the hydrogen storage system 34, correspondingly.

Fig. 6 shows a schematic cross-sectional view of a hydrogen production plant 600 according to a further embodiment of the present invention. This embodiment of the hydrogen production plant 600 differs from the embodiment 20 shown in Fig. 2 by the fact that it further features the provisions of both embodiments shown in Figs. 4 and 5. Specifically, the hydrogen production plant 600 includes the water supply pipeline 61 coupling the HPESR system 2 to the desalination/demineralization system 31 of the hydrogen production system 3 of the embodiment shown in Fig. 4 and the cooler hydraulic pipeline 62 coupling the HPESR system 2 to the compressor system 33 and/or to the hydrogen storage system 34 of the hydrogen production system 3 of the embodiment shown in Fig. 4.

Thus, similar to the embodiment shown in Fig. 4, the desalination/demineralization system 31 of the hydrogen production system 3 includes the supplementary inlet port 310a through which a portion of the water released from the HPESR system 2 can be provided into the system 31 via the water supply pipeline 61. The water supply pipeline 61 is coupled to the supplementary inlet port 310a at one end of the water supply pipeline 61 and to the water outlet pipeline 225 at its other end. The hydraulic supply flow through the supplementary inlet port 310a into the desalination/demineralization units 31 is depicted as A3.

In turn, similar to the embodiment shown in Fig. 5, the hydrogen compressor system (HCS) 33 includes the HCS cooling inlet port 33c to provide circulation of a portion of the water released from the HPESR system 2 through the heat exchanger for cooling of the hydrogen compressor system 33 during compression. Likewise, the hydrogen storage system (HSS) 34 includes the HSS cooling inlet port 34c to provide circulation of a portion of the water released from the HPESR system 2 through the corresponding heat exchanger for cooling of the hydrogen storage system 34.

The cooler hydraulic pipeline 62 is split at one end and is coupled to the HCS cooling inlet port 33c and to the HSS cooling inlet port 34c. At another end, the cooler hydraulic pipeline 62 is coupled to the water outlet pipeline 225. The hydraulic supply flow through the cooler hydraulic pipeline 62 is depicted as A30.

Similar to the embodiment shown in Fig. 4, the hydrogen production plant 600 further includes the flow-regulating valve 230 arranged in the water supply pipeline 61. The flow-regulating valve 230 is operatively coupled, for example electrically or wirelessly, to the electronic controller 41, and is configured to modulate a rate of the water flow A3 passing from the water outlet pipeline 225 into the desalination/demineralization system 31 through the supplementary inlet port 310a.

In turn, similar to the embodiment shown in Fig. 5, the hydrogen production plant 600 further includes the flow-regulating valve 233 arranged on the cooler hydraulic pipeline 62. The flow-regulating valve 233 is configured to modulate the rate of the water flow A30 passing through the cooler hydraulic pipeline 62 from the water outlet pipeline 225 into the heat exchangers of the hydrogen compressor system 33 and the hydrogen storage system 34 through the inlet port 33c and 34c, correspondingly.

Thus, the hydrogen production plant 600 can enjoy all the benefits of the embodiments shown in Figs. 4 and 5. In particular, in addition to electricity supply to the hydrogen production system 3, the HPESR system 2 can also supply pressurized water stored in the accumulator chamber 210 to the desalination/demineralization system 31, to the hydrogen compressor system 33 and/or the hydrogen storage system 34. When the water passing from the HPESR system 2 is used only as a sole water source for the desalination/demineralization system 31, the hydrogen production plant 600 can cut down on the infrastructure necessary to independently pump water into the desalination/demineralization system 31. Moreover, since the water provided from the HPESR system 2 can also be used for cooling the heat exchangers, it allows cutting down on the cooling load required for the heat-generating compression and storage processes.

Fig. 7 shows a schematic cross-sectional view of a hydrogen production plant 700, according to a further embodiment of the present invention. This embodiment of the hydrogen production plant 700 differs from the embodiment of the plant 400 as shown in Fig. 4 by the fact that the wastewater released from the wastewater outlet port 31b is used for cooling the hydrogen compressor system 33 and/or to the hydrogen storage system 34.

According to this embodiment of the present invention, the hydrogen compressor system (HCS) 33 of the hydrogen production system 3 includes an HCS heat exchanger (not shown), another HCS cooling inlet port 33d and the HCS cooling outlet port 33b. The hydrogen compressor system (HCS) 33 is configured to provide circulation of a cooling liquid through the HCS heat exchanger for cooling of the hydrogen compressor system 33 during hydrogen compression.

In turn, the hydrogen storage system (HSS) 34 includes an HSS storage heat exchanger, another HSS cooling inlet port 34d and the HSS cooling outlet port 34b. The hydrogen storage system (HSS) 34 is configured to provide circulation of a cooling liquid through the HSS heat exchanger for cooling of the hydrogen storage system 34 during hydrogen storage.

The hydrogen production plant 700 further includes a second cooler hydraulic pipeline 63 coupling the wastewater outlet port 31b of the desalination/demineralization system 31 at one end of the second cooler hydraulic pipeline 63. Another end of the second cooler hydraulic pipeline 63 is split and is coupled to the HCS cooling inlet port 33d of the hydrogen compressor system 33 and/or to the HSS cooling inlet port 34d of the hydrogen storage system 34. The hydraulic supply wastewater flow through the second cooler hydraulic pipeline 63 is depicted as B3.

This provision allows for the wastewater exiting from the desalination/demineralization system 31 to be supplied to the compressor system 33 and/or to the hydrogen storage system 34 for cooling purposes. It should be noted that internal and/or external heat exchangers can be used for cooling of the compressor system 33 and/or of the hydrogen storage system 34. According to this embodiment of the present invention, the hydrogen production plant 700 further includes another flow-regulating valve 234 arranged on the second cooler hydraulic pipeline 63. The flow-regulating valve 234 is configured to modulate the rate of the water flow B3 passing through the second cooler hydraulic pipeline 63.

Fig. 8 shows a schematic cross-sectional view of a hydrogen production plant 800, according to a further embodiment of the present invention. This embodiment of the hydrogen production plant 800 differs from the embodiment of the plant 400 shown in Fig. 4 by the fact that plant 800 further includes a pressure exchanger 7 hydraulically coupled to the HPESR system 2 and to the hydrogen production system 3. The water pressure exchanger 7 includes a high pressure inlet port 71, a low pressure inlet port 72, a first outlet port 73, and a second outlet port 74.

According to this embodiment of the present invention, the hydrogen compressor system (HCS) 33 of the hydrogen production system 3 includes an HCS heat exchanger (not shown), another HCS cooling inlet port 33d, and the HCS cooling outlet port 33b, and configured to provide circulating of a cooling liquid through the HCS heat exchanger for the cooling of the hydrogen compressor system 33 during hydrogen compression. In turn, the hydrogen storage system (HSS) 34 includes an HSS storage heat exchanger, another HSS cooling inlet port 34d, and the HSS cooling outlet port 34b, and configured to provide circulation of a cooling liquid through the HSS heat exchanger for cooling of the hydrogen storage system 34 during hydrogen storage.

According to this embodiment, the hydrogen production plant 800 includes an HPESR supply pipeline 64 coupling the high pressure inlet port 71 to the HPESR system 2. The hydrogen production plant 800 also includes a pressure exchanger water inlet pipeline 65 coupled to the low pressure inlet port 72, and is configured for extraction of water from a water body (not shown) by a water feed pump 701. The hydrogen production plant 800 also includes a third cooler hydraulic pipeline 66 coupling the first outlet port 73 to the HCS cooling inlet port 33d of compressor system 33 and/or to the HSS cooling inlet port 34d of the hydrogen storage system 34 of the hydrogen production system 3. The hydrogen production plant 800 also includes a water supply pipeline 67 coupling the second outlet port 74 to the desalination/demineralization system 31 of the hydrogen production system 3 through the supplementary inlet port 310a.

In operation, a water flow B3 exiting from the first outlet port 73 is supplied to the HCS cooling inlet port 33d of compressor system 33 and/or to the HSS cooling inlet port 34d of the hydrogen storage system 34 for cooling purposes, thus cutting down on the cooling load for compressing and storing the hydrogen product. Additionally, the water pressure exchanger 7 transfers the pressure of a water flow A3 of the water passing through HPESR supply pipeline 64 from the HPESR system 2 into the high pressure inlet port 71 of the water pressure exchanger 7 to the water that is sucked in through the low pressure inlet port 72 by water feed pump 701. This water is then supplied to the desalination/demineralization system 31 through the water supply pipeline 67.

Thus, in addition to electricity supply to the hydrogen production system 3, the HPESR system 2 also supplies pressurized water stored in the accumulator chamber 210 to the desalination/demineralization system 31, to the hydrogen compressor system 33, and/or the hydrogen storage system 34. When the water passing from the HPESR system 2 is used only as a sole water source for the system 31, the hydrogen production plant 800 can cut down on the infrastructure necessary to independently pump water into the desalination/demineralization system 31. Moreover, since the water provided from the HPESR system 2 can also be used for cooling the heat exchangers, it allows cutting down on the cooling load required for the heat-generating compression and storage processes, and to reduce the associated electrical consumption, as well as operations, maintenance and replacement costs.

Fig. 9 shows a schematic cross-sectional view of a hydrogen production plant 900, according to a further embodiment of the present invention. This embodiment of the hydrogen production plant 900 differs from the embodiment of the plant 20 shown in Fig. 2 by the fact that it further includes a support platform 9 located in a body of water 8, for example, in an offshore environment.

The support platform 9 can, for example, include one or more fixed offshore platforms and/or floating offshore platforms arranged above a water surface or suspended within the water 8 below the water surface. The structure of the support platform 9 may provide support for ancillary systems and services pertaining to, but not limited to, offshore wind farm operation/maintenance systems, fish farming, aquaculture, oil and gas infrastructures, etc. The structure of the support platform 9 may also provide support for a floating artificial island that can utilize the hydrogen product produced by the hydrogen production system 3, and/or electricity generated by the HPESR system 2 for a grid, and water for cooling buildings and technical systems, as well as for other services. According to an embodiment of the present invention, the support platform 9 includes a gas chamber 91 having a volume for holding a compressed gas at the same pressure as that held within the pressure containment system 21 of the HPESR system 2.

When the support platform 9 is configured as a floating support platform, the volume of the gas chamber 91 can have a sufficient value to provide necessary buoyant force to the support platform 9. In this case, the gas chamber 91 can serve a dual role: (i) to provide the necessary upthrust to support the facilities mounted on the support platform 9 and (ii) to serve as a platform for holding an extended gas chamber 91.

The gas chamber 91 is interconnected to the accumulator chamber 210 of the pressure containment system 21 of the HPESR system 2 through a pneumatic hose 26. The pneumatic hose 26 includes a pneumatic conduit that provides a pneumatic communication enabled for linking the compressed gas volumes of the gas chamber 91 and the accumulator chamber 210. The pneumatic hose 26 enables effectively increasing a volume of the compressed gas 212 within the accumulator chamber 210, thereby increasing the energy storage capacity of the HPESR system 2 without compromising any hydrodynamic properties of the support platform 9 supporting the RE electrical power unit(s) 12 or other supported devices. The increase of the compressed gas volume also enables improving the pressure transient response characteristics of the HPESR system 2 under the influence of an intermittent intake of water supplied by the water pressurization system 221 into the accumulator chamber 210.

It should be noted that although the layout of the embodiment shown in Fig. 2 is used for description of the hydrogen production plant 900, the application of the support platform 9 can also be applied, mutatis mutandis, to all other embodiments shown in Fig. 4 through Fig. 8.

Fig. 10 shows a schematic cross-sectional view of a hydrogen production plant 1000, according to a further embodiment of the present invention. In this embodiment, the electrical power system 1 is deployed on the support platform 9 located in the body of water 8.

It should be noted that although the layout of the embodiment shown in Fig. 2 is used for description of the hydrogen production plant 1000, the arrangement of the electrical power system 1 on the support platform 9 can also be applied, mutatis mutandis, to all other embodiments of the hydrogen production plant shown in Fig. 4 through Fig. 8. Fig. 11 shows a schematic cross-sectional view of a hydrogen production plant 1100, according to a further embodiment of the present invention. Contrary to the embodiment shown in Fig. 9, in the case shown in Fig. 10, the hydrogen production system 3 rather than the electrical power system 1 is located in a body of water 8, for example in an offshore environment. As shown in Fig. 11, the hydrogen production system 3 is deployed on the support platform 9.

It should be noted that although the layout of the embodiment shown in Fig. 2 is used for description of the hydrogen production plant 1100, the arrangement of the hydrogen production system 3 on the support platform 9 can also be applied, mutatis mutandis, to all other embodiments of the hydrogen production plant shown in Fig. 4 through Fig. 8.

As such, those skilled in the art to which the present invention pertains, can appreciate that while the present invention has been described in terms of preferred embodiments, the concept upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, systems and processes for carrying out the several purposes of the present invention.

The various illustrative logical blocks, modules, and algorithm steps described in connection with the embodiments disclosed herein can be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. The described functionality can be implemented in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the disclosure.

Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting.

Reference numerals and symbols appearing in the appended claims are by way of illustration only and shall have no limiting effect on the scope of the claims.

Finally, it should be noted that the words “having”, “comprising” and “including” as used throughout the description and appended claims is to be interpreted to mean “including but not limited to”. It is important, therefore, that the scope of the invention is not construed as being limited by the illustrative embodiments set forth herein. Other variations are possible within the scope of the present invention as defined in the appended claims. Other combinations and sub-combinations of features, functions, elements and/or properties may be claimed through amendment of the present claims or presentation of new claims in this or a related application. Such amended or new claims, whether they are directed to different combinations or directed to the same combinations, whether different, broader, narrower or equal in scope to the original claims, are also regarded as included within the subject matter of the present description.