TECHNICAL FIELD

[0001] The present disclosure relates to an integrated energy conversion and storage system.

BACKGROUND

[0002] Over the past decades, energy storage technologies have continued to develop, adapt, and innovate in response to the evolution of the energy mix and meet the increasing electricity demand. Among all different energy storage technologies, hydrogen energy storage has drawn interest due to the much higher storage capacity compared to batteries, mechanical energy storage. Electricity can be converted into hydrogen by electrolysis, alternatively using three types of electrolysis units: alkaline electrolysis (AE) type, polymer electrolyte membrane (PEM) electrolysis type, and solid oxide electrolysis (SOE) type. The hydrogen can be then stored and eventually re-electrified.

[0003] However, the round-trip efficiency of hydrogen energy storage today is lower than other storage technologies. One reason is that electrolysis units consume much electricity to maintain at a relatively high operating temperature since their catalytic reaction rate as well as specific resistance is heavily dependent on temperature and the higher the temperature, the higher the efficiency. For example, SOE requires high-temperature steam (500°C ~ 600°C) as feedstock, and AE and PEM require high-temperature water (60°C ~ 90°C) as feedstock, causing additional electricity consumption to heat the water.

SUMMARY

[0004] In view of the above, the present disclosure aims to provide an integrated energy conversion and storage system that overcomes the defects of the prior art.

[0005] To this end, a first aspect of the present disclosure provides an integrated energy conversion and storage system comprising: an energy conversion module configured for performing conversion from electric energy to hydrogen energy or bidirectional conversion between electric energy and hydrogen energy and at least comprising an electrolysis unit configured for performing electrolysis and generating hydrogen and a power conversion unit configured for supplying DC power to the electrolysis unit; an energy storage module comprising at least one of a hydrogen storage unit and a thermal storage unit; an energy recovery module configured for recovering thermal energy from the energy conversion module and supplying recovered thermal energy to the electrolysis unit; and at least one controller configured for controlling the integrated energy conversion and storage system.

[0006] The energy recovery module of the integrated energy conversion and storage system according to the first aspect of the present disclosure can recover thermal energy from the energy conversion module and supply recovered thermal energy to the electrolysis unit, which allows recovered thermal energy to be reused to heat the feedstock for the electrolysis unit. This can reduce electric energy needed by the electrolysis unit for maintaining a relatively high operating temperature and improve the efficiency of the system.

[0007] According to a preferred embodiment of the present disclosure, the energy conversion module comprises a plurality of electrolysis units, and the energy recovery module is configured for supplying recovered thermal energy to at least one of the plurality of electrolysis units.

[0008] According to a preferred embodiment of the present disclosure, the energy conversion module is capable of operating in a charging mode in which the electrolysis unit is supplied with DC power to perform electrolysis. The at least one controller is configured for performing coordinated control of at least one of supply of DC power to the electrolysis unit by the power conversion unit, supply of recovered thermal energy to the electrolysis unit by the energy recovery module and operation of the electrolysis unit in the charging mode.

[0009] According to a preferred embodiment of the present disclosure, the energy recovery module comprises at least one of a heat pump, a heat exchanger and a fluid pump.

[0010] According to a preferred embodiment of the present disclosure, the energy storage module comprises a thermal storage unit configured for storing thermal energy recovered by the energy recovery module.

[0011] According to a preferred embodiment of the present disclosure, the energy conversion module comprises a hydrogen-fueled gas turbine and is capable of operating in a discharging mode in which the hydrogen-fueled gas turbine is supplied with hydrogen to generate electricity. The energy recovery module is configured for recovering thermal energy from steam generated by the hydrogen-fueled gas turbine in the discharge mode. [0012] According to a preferred embodiment of the present disclosure, the at least one controller is configured for performing coordinated control of at least one of supply of hydrogen from the hydrogen storage unit to the hydrogen-fueled gas turbine, operation of the hydrogen-fueled gas turbine, recovery of thermal energy by the energy recovery module and storage of recovered thermal energy in the thermal storage unit in the discharging mode.

[0013] According to a preferred embodiment of the present disclosure, the thermal storage unit is in form of a thermal-insulation storage tank for storing at least part of the steam and the energy recovery module supplies steam from the thermal-insulation storage tank to the electrolysis unit as feedstock when the electrolysis is performed.

[0014] According to a preferred embodiment of the present disclosure, the thermal storage unit is configured for storing thermal energy recovered from at least part of the steam in storage medium and the energy recovery module supplies thermal energy from the storage medium to the feedstock for the electrolysis unit when the electrolysis is performed.

[0015] According to a preferred embodiment of the present disclosure, the energy conversion module further comprises a steam turbine, and a first part and a second part of the steam generated by the hydrogen-fueled gas turbine are respectively supplied to the thermal storage unit and the steam turbine in the discharging mode. The at least one controller is configured for determining the ratio of the first part of the steam to the second part of the steam.

[0016] According to a preferred embodiment of the present disclosure, the electrolysis unit is a SOE-type electrolysis unit.

[0017] According to a preferred embodiment of the present disclosure, the integrated energy conversion and storage system further comprises a heating unit for heating feedstock for the electrolysis unit and a sensing unit for sensing temperature of the electrolysis unit. The at least one controller is configured for performing coordinated control of at least one of supply of feedstock to the electrolysis unit, supply of thermal energy from the thermal storage unit to the electrolysis unit by the energy recovery module, and operation of the heating unit based on temperature data sensed by the sensing unit to maintain the electrolysis unit at operating temperature when the electrolysis is performed.

[0018] According to a preferred embodiment of the present disclosure, the energy recovery module is configured for recovering thermal energy from the power conversion unit.

[0019] According to a preferred embodiment of the present disclosure, the energy recovery module comprises a fluid channel within which a heat transfer fluid flows, wherein the fluid channel extends through the power conversion unit to allow the heat transfer fluid to receive thermal energy from the power conversion unit.

[0020] According to a preferred embodiment of the present disclosure, the heat transfer fluid is feedstock for the electrolysis unit, and wherein the fluid channel is fluidly communicated with the electrolysis unit to allow the feedstock to receive thermal energy from the power conversion unit and be supplied into the electrolysis unit.

[0021] According to a preferred embodiment of the present disclosure, the power conversion unit comprises a transformer and/or a rectifier.

[0022] According to a preferred embodiment of the present disclosure, the power conversion unit is configured to have a predetermined power loss by selecting a material of an iron core and/or a cross-sectional area of a winding in the power conversion unit.

[0023] According to a preferred embodiment of the present disclosure, the power conversion unit comprises a rectifier, and the at least one controller is configured for controlling the rectifier to adjust harmonic current on AC side of the rectifier and/or switching frequency of the rectifier for adjusting power loss of the power conversion unit.

[0024] According to a preferred embodiment of the present disclosure, the integrated energy conversion and storage system further comprises a heating unit for heating feedstock for the electrolysis unit and a sensing unit for sensing temperature of the electrolysis unit. The at least one controller is configured for performing coordinated control of at least one of supply of feedstock to the electrolysis unit, supply of thermal energy from the power conversion unit to the electrolysis unit by the energy recovery module, operation of the rectifier, and operation of the heating unit based on temperature data sensed by the sensing unit to maintain the electrolysis unit at operating temperature when the electrolysis is performed.

[0025] According to a preferred embodiment of the present disclosure, the electrolysis unit is a PEM-type electrolysis unit or an AE-type electrolysis unit.

[0026] A second aspect of the present disclosure provides a method for operating the integrated energy conversion and storage system according to the first aspect comprising: providing the integrated energy conversion and storage system; and controlling the integrated energy conversion and storage system by the at least one controller. [0027] The integrated energy conversion and storage system and method for operating the same according to the present disclosure can offer the benefits of higher practicality, higher energy conversion efficiency and lower capital cost.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Other features and advantages of the present disclosure will be better understood through the following preferred embodiments described in detail with reference to the accompanying drawings, in which the same reference numerals indicate the same or similar components.

[0029] FIG. 1 is a schematic diagram of an integrated energy conversion and storage system according to a first embodiment of the present disclosure;

[0030] FIG. 2 is a schematic diagram of the integrated energy conversion and storage system of FIG. 1 in a charging mode;

[0031] FIG. 3 is a schematic diagram of the integrated energy conversion and storage system of FIG. 1 in a discharging mode;

[0032] FIG. 4 is a schematic block diagram of temperature control on the electrolysis unit of the integrated energy conversion and storage system of FIG. 1;

[0033] FIG. 5 A is a schematic diagram of an integrated energy conversion and storage system according to a first example of a second embodiment of the present disclosure;

[0034] FIG. 5B is a schematic diagram of an integrated energy conversion and storage system according to a second example of the second embodiment of the present disclosure;

[0035] FIG. 5C is a schematic diagram of an integrated energy conversion and storage system according to a third example of the second embodiment of the present disclosure;

[0036] FIG. 5D is a schematic diagram of an integrated energy conversion and storage system according to a fourth example of the second embodiment of the present disclosure; and

[0037] FIG. 6 is a schematic block diagram of temperature control on the electrolysis unit of the integrated energy conversion and storage system of FIGS. 5A-5D. DETAILED DESCRIPTION

[0038] The implementation and usage of the embodiments are discussed in detail below. However, it should be understood that the specific embodiments discussed are merely intended to illustrate specific ways of implementing and using the present disclosure, and are not intended to limit the protection scope of the present disclosure.

[0039] FIGS. 1-4 show an integrated energy conversion and storage system 10 according to a first embodiment of the present disclosure.

[0040] Referring to FIGS. 1-3, the integrated energy conversion and storage system 10 includes an energy conversion module 100, an energy storage module 200, an energy recovery module 300 and at least one controller 400.

[0041] Referring to FIG. 1, the energy conversion module 100 may be configured for performing bidirectional conversion between electric energy and hydrogen energy. The energy conversion module 100 may be electrically coupled to at least one renewable-energy power station 20 which can generate electricity out of a renewable source or a power grid 30. For example, the renewable-energy power station 20 may be a wind power station, a solar power station or any other suitable power station generating electricity out of a renewable source. The renewable-energy power station 20 may be electrically coupled to the power grid 30 to supply electricity from the renewable-energy power station 20 to the power grid 30 to meet the electric energy demands of the consumers in the power grid 30. It should be understood that the power grid 30 may also have access to other power station (not shown), such as a fossil-fuel power station.

[0042] The energy conversion module 100 may include at least one electrolysis unit 102 configured for performing electrolysis and generating hydrogen and at least one power conversion unit 104 configured for supplying DC power to the least one electrolysis unit 102, so as to realize the conversion from electric energy to chemical energy including hydrogen energy.

[0043] The power conversion unit 104 may be electrically coupled to the renewable-energy power station 20 and the power grid 30 as well as the electrolysis unit 102. The power conversion unit 104 may include a rectifier 106 for converting AC power (for example, from the renewable-energy power station 20 and/or the power grid 30) to DC power and supplying DC power to the electrolysis unit 102. The power conversion unit 104 may further include a transformer 108 electrically coupled to the rectifier 106.

[0044] The electrolysis unit 102 may include one or more electrolysis cell, with each electrolysis cell including one anode and one cathode. The electrolysis unit 102 may be an SOE-type electrolysis unit 102 which requires high-temperature steam (for example, 500°C ~ 600°C) as feedstock to maintain at a relatively high operating temperature during electrolysis. The electrolysis unit 102 may use DC power from the rectifier 106 to perform electrolysis and generate hydrogen and oxygen.

[0045] Thus, the energy conversion module 100 is capable of operating in a charging mode in which the electrolysis unit 102 is supplied with DC power to perform electrolysis.

[0046] The energy storage module 200 may include a hydrogen storage unit 202 and an oxygen storage unit 204 for storing hydrogen and oxygen generated during the electrolysis.

[0047] The energy conversion module 100 may also include at least one hydrogen- fueled gas turbine 110 and at least one first electric generator 112 coupled with the hydrogen- fueled gas turbine(s) 110 for realizing the conversion from chemical energy to electric energy. The hydrogen- fueled gas turbine 110 may be fluidly communicated with the hydrogen storage unit 202 and the oxygen storage unit 204. Thus, the energy conversion module 100 is capable of operating in a discharging mode in which the hydrogen and oxygen stored in the energy storage module 200 is fed into and combusted in the hydrogen- fueled gas turbine 110 with high-temperature steam (for example, 300°C ~ 400°C) generated and the first electric generator 112 is driven to generate electricity.

[0048] The energy conversion module 100 may further include at least one steam turbine 114 and at least one second electric generator 116 coupled with the steam turbine(s) 114. The steam turbine 114 may be fluidly communicated with the hydrogen-fiieled gas turbine 110, such that the steam turbine 114 may use the high-temperature steam generated by the hydrogen- fueled gas turbine 110 to generate electricity.

[0049] The energy recovery module 300 may recover thermal energy from the energy conversion module 100 and supply recovered thermal energy to the electrolysis unit 102. If the energy conversion module 100 includes a plurality of electrolysis units 102, the energy recovery module 300 may supply recovered thermal energy to at least one of the plurality of electrolysis units 102. The energy recovery module 300 allows waste heat generated during the operation of the energy conversion module 100 to be recovered/ collected and supplied to the electrolysis unit 102. The recovered waste heat can be reused to, for example, heat the feedstock for the electrolysis unit 102. This can reduce electric energy needed by the electrolysis unit 102 for maintaining a relatively high operating temperature.

[0050] Referring to FIGS. 2 and 3, the at least one controller 400 may be configured for controlling the integrated energy conversion and storage system 10. The at least one controller 400 may be in form of a distributed control system (DSA) or a supervisory control and data acquisition system (SCADA system), and may perform model-based control (e.g., using model(s) for units or/and modules in the system, for example, model for the electrolysis unit) and/or coordinated/optimal control based on, for example, electric energy demand/availability related information.

[0051] As shown in FIG. 2, the at least one controller 400 may control the energy conversion module 100 to operate in the charging mode, for example, when the electric energy available from the renewable-energy power station 20 exceeds the electric energy demands from the power grid 30 on the renewable-energy power station 20, e.g., during off-peak hours. In the charging mode, the excess electric energy and recovered thermal energy can be directed to the electrolysis unit 102 and converted into chemical energy in hydrogen and oxygen, which can be further stored in the hydrogen storage unit 202 and the oxygen storage unit 204.

[0052] As shown in FIG. 3, the at least one controller 400 may control the energy conversion module 100 to operate in the discharging mode, for example, when the electric energy available from the renewable-energy power station 20 cannot satisfy the electric energy demands from the power grid 30 on the renewable-energy power station 20, e.g., during peak hours. In the discharging mode, the hydrogen and oxygen stored in the hydrogen storage unit 202 and the oxygen storage unit 204 can be fed into the hydrogen- fueled gas turbine 110 and the chemical energy in the hydrogen and oxygen can be then converted into electric energy by means of the hydrogen- fueled gas turbine 110 and the first electric generator 112 as well as the steam turbine 114 and the second electric generator 116, so as to guarantee a stable electric energy supply in the power grid 30. At the same time, surplus thermal energy/waste heat generated by the energy conversion module 100 can be recovered by the energy recovery module 300.

[0053] By switching the operation modes of the energy conversion module 100, the power fluctuation caused by the renewable-energy power station 20 can be suppressed, allowing a stable electric energy supply. [0054] Referring to FIGS. 2 and 3, the energy storage module 200 may further include at least one thermal storage unit 206. The thermal storage unit 206 may store thermal energy recovered by the energy recovery module 300 in the discharging mode, and may release stored thermal energy, which may be further supplied to the electrolysis unit 102, in the charging mode. The energy recovery module 300 may include at least one of a heat pump, a heat exchanger and a fluid pump for thermal energy transfer between the energy conversion module 100 and the thermal storage unit 206. Optionally, the thermal storage unit 206 may be integrated with the energy recovery module 300.

[0055] In the illustrated embodiment, the energy recovery module 300 may recover thermal energy from the high-temperature steam ST generated by the hydrogen- fueled gas turbine 110 in the discharge mode. A first part Pl and a second part P2 of the steam generated by the hydrogen- fueled gas turbine 110 may be respectively supplied to the thermal storage unit 206 and the steam turbine 114. The at least one controller 400 may determine the ratio of the first part Pl of the steam to the second part P2 of the steam in the discharging mode based on the electric energy demands from the power grid 30. In the illustrated embodiment, a part of the steam generated by the hydrogen- fueled gas turbine 110 is supplied to the thermal storage unit 206 and the rest of the steam is supplied to the steam turbine 114.

[0056] Optionally, the thermal storage unit 206 may be a thermal-insulation storage tank for storing the first part Pl of the steam ST. The energy recovery module 300 may include a fluid pump. The energy recovery module 300 may recover steam from the hydrogen-fueled gas turbine 110 and deliver the steam to the thermal-insulation storage tank 206 in the discharging mode and supply steam from the thermal-insulation storage tank 206 to the electrolysis unit 102 as feedstock in the charging mode.

[0057] The at least one controller 400 may perform coordinated control of at least one of supply of DC power to the electrolysis unit 102 by the power conversion unit 104, supply of recovered steam from the thermal-insulation storage tank 206 to the electrolysis unit 102 by the energy recovery module 300 and operation of the electrolysis unit 102 in the charging mode. The at least one controller 400 may perform coordinated control of at least one of supply of hydrogen from the hydrogen storage unit 202 to the hydrogen- fueled gas turbine 110, supply of oxygen from the oxygen storage unit 204 to the hydrogen-fueled gas turbine 110, operation of the hydrogen-fueled gas turbine 110 and the first electric generator 112, operation of the steam turbine 114 and the second electric generator 116, recovery of steam by the energy recovery module 300 and storage of recovered steam in the thermal-insulation storage tank 206 in the discharging mode.

[0058] Optionally, the thermal storage unit 206 may be configured for storing thermal energy recovered from the first part Pl of the steam ST in storage medium. The storage medium may be at least one of a sensible heat storage medium (such as, molten salt or metals), a latent heat storage medium/phase-change material (including but not limited to salts, polymers, gels, paraffin waxes and metal alloys) and thermo-chemical heat storage medium/thermo-chemical materials (including but not limited to salt hydrates and zeolites). The energy recovery module 300 may include at least one of a heat pump and a heat exchanger. The energy recovery module 300 may recover thermal energy from the first part Pl of the steam ST, which is further stored in the storage medium, in the discharging mode, and the energy recovery module 300 may supply thermal energy from the storage medium to the feedstock for the electrolysis unit 102 in the charging mode. In other words, in the charging mode, the recovered thermal energy can be reused to heat the feedstock such as water or relatively low-temperature steam before the feedstock is fed into the electrolysis unit 102 to provide high-temperature steam for the electrolysis unit 102.

[0059] The at least one controller 400 may perform coordinated control of at least one of supply of DC power to the electrolysis unit 102 by the power conversion unit 104, supply of recovered thermal energy from the storage medium to the feedstock for electrolysis unit 102 by the energy recovery module 300 and operation of the electrolysis unit 102 in the charging mode. The at least one controller 400 may perform coordinated control of at least one of supply of hydrogen from the hydrogen storage unit 202 to the hydrogen- fueled gas turbine 110, supply of oxygen from the oxygen storage unit 204 to the hydrogen- fueled gas turbine 110, operation of the hydrogen-fiieled gas turbine 110 and the first electric generator 112, operation of the steam turbine 114 and the second electric generator 116, recovery of thermal energy by the energy recovery module 300 and storage of recovered thermal energy in the storage medium in the discharging mode. In the case that the thermal storage unit 206 can store recovered thermal energy in storage medium, the thermal storage unit 206 and the energy recovery module 300 are also suitable for PEM-type or AE-type electrolysis unit.

[0060] Referring to FIGS. 1 and 4, the integrated energy conversion and storage system 10 may include at least one heating unit 502 for heating the feedstock for the electrolysis unit(s) 102 before the feedstock is fed into the electrolysis unit(s) 102. This is advantageous when the thermal energy recovered from the energy conversion module 100 is not enough to maintain the electrolysis unit(s) 102 at a relatively high operating temperature. The heating unit 502 may be in form of an electrical heater or a heat pump. The integrated energy conversion and storage system 10 may also include at least one sensing unit 504 for sensing the temperature of the electrolysis unit(s) 102. Herein, sensing the temperature of the electrolysis unit 102 may include but not limit to sensing the temperature of feedstock at the inlet of the electrolysis unit 102 or the temperature inside the electrolysis unit 102. The sensing unit 504 may include a temperature sensor. Optionally, one electrolysis unit 102 may be equipped with one or more heating unit 502 and/or sensing unit 504, or more than one electrolysis unit 102 may share one or more heating unit 502 and/or sensing unit 504. Optionally, the sensing unit 504 may be integrated with the electrolysis unit 102.

[0061] The at least one controller 400 may perform coordinated control of at least one of supply of feedstock to the electrolysis unit 102, supply of thermal energy from the thermal storage unit 206 to the electrolysis unit 102 by the energy recovery module 300 and operation of the heating unit 502 based on temperature data sensed by the sensing unit 504, so as to maintain the electrolysis unit 102 at operating temperature when the electrolysis is performed.

[0062] In the illustrated embodiment, the electrolysis unit(s) 102 in the integrated energy conversion and storage system 10 would require less additional power consumption for high-temperature feedstock due to the thermal storage unit 206 and the energy recovery module 300, so that the integrated energy conversion and storage system 10 has a higher efficiency than a conventional system. In addition, by full coordination of conversion among electric energy, thermal energy and hydrogen energy as well as hydrogen storage and thermal storage, the operation of the integrated energy conversion and storage system 10 is optimized and controlled to reach an optimal state in multiple operation modes.

[0063] FIGS. 5A-6 show an integrated energy conversion and storage system 10 according to a second embodiment of the present disclosure.

[0064] Referring to FIGS. 5A-6, the integrated energy conversion and storage system 10 includes an energy conversion module 100, an energy storage module 200, an energy recovery module 300 and at least one controller 400.

[0065] The energy conversion module 100 may receive electric energy from a power source, for example, a power grid 30 having access to wind power station, solar power station, fossil-fuel power station and so on. The energy conversion module 100 may be configured for at least performing conversion from electric energy to hydrogen energy and may include at least one electrolysis unit 102 configured for performing electrolysis and generating hydrogen and at least one power conversion unit 104 configured for supplying DC power to the electrolysis unit 102.

[0066] The power conversion unit 104 may be electrically coupled to the power grid 30. The power conversion unit 104 may include a rectifier 106 for converting AC power from the power grid 30 to DC power and supplying DC power to the electrolysis unit 102. The power conversion unit 104 may further include a transformer 108 electrically coupled to the rectifier 106.

[0067] The electrolysis unit 102 may include one or more electrolysis cell, with each electrolysis cell including one anode and one cathode. The electrolysis unit 102 may be a PEM-type electrolysis unit 102 or an AE-type electrolysis unit 102 which requires high-temperature water (for example, 60°C ~ 90°C) as feedstock to maintain at a relatively high operating temperature during electrolysis. The electrolysis unit 102 may use DC power from the rectifier 106 to perform electrolysis, i.e., to split water into hydrogen and oxygen. Thus, the energy conversion module 100 is capable of operating in a charging mode in which the electrolysis unit 102 is supplied with DC power to perform electrolysis.

[0068] The energy storage module 200 may include a hydrogen storage unit 202 and an oxygen storage unit 204 for storing hydrogen and oxygen generated during the electrolysis.

[0069] The energy recovery module 300 may recover thermal energy from the power conversion unit 104 and supply recovered thermal energy to the electrolysis unit 102. If the energy conversion module 100 includes a plurality of electrolysis units 102, the energy recovery module 300 may supply recovered thermal energy to at least one of the plurality of electrolysis units 102.

[0070] The energy recovery module 300 allows waste heat generated during the operation of the power conversion unit 104 to be recovered/ collected and supplied to the electrolysis unit 102. The recovered waste heat can be reused to heat the feedstock for the electrolysis unit 102 before the feedstock is fed into the electrolysis unit 102, reducing electric energy needed by the electrolysis unit 102 for maintaining a relatively high operating temperature. This is especially suitable for a PEM-type electrolysis unit since the PEM-type electrolysis unit has a higher efficiency than an AE-type electrolysis unit and its self-heating may be not sufficient to sustain the temperature inside the unit at the desired level. In addition, this is especially suitable for mid-scale electrolysis unit (for example, mid-scale PEM-type electrolysis unit), since for large-scale electrolysis unit, the heat generated by electrolysis may be sufficient to sustain the temperature of the unit or even be surplus and need to be dissipated.

[0071] The at least one controller 400 may be configured for controlling the integrated energy conversion and storage system 10. The at least one controller 400 may be in form of a distributed control system (DSA) or a supervisory control and data acquisition system (SCADA system), and may perform model-based control (e.g., using model(s) for units or/and modules in the system, for example, model for the electrolysis unit) and/or coordinated/optimal control based on, for example, electric energy availability related information. The at least one controller 400 may perform coordinated control of at least one of supply of DC power to the electrolysis unit 102 by the power conversion unit 104, supply of recovered thermal energy to the electrolysis unit 102 by the energy recovery module 300 and operation of the electrolysis unit 102 in the charging mode.

[0072] The energy recovery module 300 may include at least one of a heat pump, a heat exchanger and a fluid pump for thermal energy transfer between the power conversion unit 104 and the electrolysis unit 102.

[0073] The energy recovery module 300 may include at least one fluid channel 302 within which a heat transfer fluid flows, and the at least one fluid channel 302 extends through the power conversion unit 104 to allow the heat transfer fluid to receive thermal energy from the power conversion unit 104.

[0074] In the illustrated embodiment, the heat transfer fluid may be the feedstock for the electrolysis unit 102. The at least one fluid channel 302 may extend through the power conversion unit 104 and is fluidly communicated with the electrolysis unit 102 to allow the feedstock to receive thermal energy/waste heat from the power conversion unit 104 and be supplied into the electrolysis unit 102. The energy recovery module 300 may include at least one fluid pump to allow the feedstock to flow within the at least one fluid channel 302.

[0075] As shown in FIG. 5A, in a first example of the second embodiment, the fluid channel 302 may extend through the transformer 108. The feedstock for the electrolysis unit 102 may flow through the transformer 108, recover the waste heat due to the power loss of the transformer 108 and then flow into the electrolysis unit 102, such that the waste heat of the transformer 108 can be reused for the electrolysis unit 102.

[0076] As shown in FIG. 5B, in a second example of the second embodiment, the fluid channel 302 may extend through the rectifier 106. The feedstock for the electrolysis unit 102 may flow through the rectifier 106, recover the waste heat due to the power loss of the rectifier 106 and then flow into the electrolysis unit 102, such that the waste heat of the rectifier 106 can be reused for the electrolysis unit 102.

[0077] As shown in FIG. 5C, in a third example of the second embodiment, the fluid channel 302 may include a first section 304 and a second section 306. The first section 304 and the second section 306 respectively extend through the transformer 108 and the rectifier 106, and are fluidly connected in series to each other. The feedstock for the electrolysis unit 102 may successively flow through the transformer 108 and the rectifier 106, recover the waste heat due to the power loss of the transformer 108 and the rectifier 106 and then flow into the electrolysis unit 102, such that the waste heat of the transformer 108 and the rectifier 106 can be reused for the electrolysis unit 102.

[0078] As shown in FIG. 5D, in a fourth example of the second embodiment, the fluid channel 302 may include a first section 304 and a second section 306. The first section 304 and the second section 306 respectively extend through the transformer 108 and the rectifier 106, and are fluidly connected in parallel to each other. Two parts of the feedstock for the electrolysis unit 102 may respectively flow through the transformer 108 and the rectifier 106 via the first section 304 and the second section 306 at the same time, recover the waste heat due to the power loss of the transformer 108 and the rectifier 106 and then flow into the electrolysis unit 102, such that the waste heat of the transformer 108 and the rectifier 106 can be reused for the electrolysis unit 102.

[0079] Alternatively, the heat transfer fluid may be any other suitable fluid, and the fluid channel may extend through the power conversion unit 104 and is thermally coupled with the electrolysis unit 102 to allow the heat transfer fluid to receive thermal energy from the power conversion unit 104 and supply thermal energy to feedstock for the electrolysis unit 102. Here, the fluid channel being thermally coupled with the electrolysis unit 102 means that the heat transfer fluid in the fluid channel may perform heat exchange with the feedstock for the electrolysis unit 102. [0080] By recovering the waste heat from the power conversion unit 104 (the transformer 108 and/or the rectifier 106), the power conversion unit 104 can be cooled by the feedstock for the electrolysis unit 102, allowing to omit the cooling system for the power conversion unit 104 and save the cost. Besides, the waste heat of the power conversion unit 104 can be reused to heat the feedstock for the electrolysis unit 102, increasing the total efficiency of the whole system.

[0081] It should be understood that the energy recovery module 300 may also be used together with a thermal storage unit to store recovered thermal energy/waste heat from the power conversion unit 104 and reuse it for the electrolysis unit 102 later.

[0082] Optionally, the transformer 108 and/or the rectifier 106 may be configured to have a predetermined power loss by selecting a material of an iron core and/or a cross-sectional area of a winding in the transformer 108 and/or the rectifier 106. Here, a predetermined power loss means a power loss with a predetermined value or a power loss falling into a predetermined value range. For example, the transformer 108 and/or the rectifier 106 may be configured to have a power loss greater than 5%. A power conversion unit 104 with increased power loss due to the hardware design may be intentionally used to increase waste heat available for the electrolysis unit 102. For example, an increased copper loss of the power conversion unit 104 can be realized by decreasing cross-sectional area of the winding and an increased iron loss can be realized by selecting a cheaper material for the iron core. Besides, the cost of the power conversion unit 104 may be reduced when hardware design thereof is changed to increase power loss.

[0083] Optionally, the at least one controller 400 may include a rectifier controller and control the rectifier 106 to adjust harmonic current on AC side of the rectifier 106 and/or switching frequency of the rectifier 106 for adjusting power loss of the power conversion unit 104 based on the desired temperature of the electrolysis unit 102 and the real-time temperature of the electrolysis unit 102 (for example, desired or real time temperature of feedstock at the inlet of the electrolysis unit 102 or desired or real time temperature inside the electrolysis unit 102). For one example, at least one of AC harmonic frequency, amplitude of AC harmonic, number of AC harmonics on AC side of the rectifier 106 may be increased to increase the power loss of the rectifier 106 and/or the transformer 108 and provide more waste heat to the electrolysis unit 102. For another example, switching frequency of the rectifier 106 may be increased to increase the power loss of the rectifier 106 and provide more waste heat to the electrolysis unit 102. The rectifier controller may be integrated inside the rectifier 106. [0084] The integrated energy conversion and storage system 10 may also include at least one sensing unit 504 for sensing the temperature of the electrolysis unit(s) 102. Herein, sensing the temperature of the electrolysis unit 102 may include but not limit to sensing the temperature of feedstock at the inlet of the electrolysis unit 102 or the temperature inside the electrolysis unit 102. The sensing unit 504 may be in form of a temperature sensor. Optionally, the sensing unit 504 may be integrated with the electrolysis unit 102.

[0085] Referring to Fig. 6, the at least one controller 400 may perform coordinated control of at least one of supply of feedstock to the electrolysis unit 102, supply of thermal energy/waste heat from the power conversion unit 104 to the electrolysis unit 102 by the energy recovery module 300, and operation of the rectifier 106 based on temperature data sensed by the sensing unit 504 to maintain the electrolysis unit 102 at operating temperature when the electrolysis is performed/when the energy conversion module 100 is in the charging mode. In the examples shown in FIGS.5A-5D, the supply of feedstock to the electrolysis unit 102 and the supply of thermal energy from the power conversion unit 104 to the electrolysis unit 102 may both be realized by the energy recovery module 300.

[0086] Optionally, the integrated energy conversion and storage system 10 may further include at least one heating unit 502 for heating the feedstock for the electrolysis unit(s) 102 before the feedstock is fed into the electrolysis unit(s) 102. This is advantageous when the thermal energy recovered from the power conversion unit 104 is not enough to maintain the electrolysis unit(s) 102 at a relatively high operating temperature. The heating unit 502 may be in form of an electrical heater or a heat pump. The heating unit may have an adjustable heating power or have a certain heating power. The at least one controller 400 may perform coordinated control of at least one of supply of feedstock to the electrolysis unit 102, supply of thermal energy/waste heat from the power conversion unit 104 to the electrolysis unit 102 by the energy recovery module 300, operation of the rectifier 106, and operation of the heating unit 502 based on temperature data sensed by the sensing unit 504 to maintain the electrolysis unit 102 at operating temperature when the electrolysis is performed.

[0087] It should be understood that, compared with the solution in which waste heat from the power conversion unit 104 is not reused, the heating unit 502 in the second embodiment may be configured to have a lower heating power and even may be cancelled, reducing the cost of integrated energy conversion and storage system 10. [0088] The technical content and technical features of the present disclosure have been disclosed above. However, it is conceivable that, under the creative ideas of the present disclosure, those skilled in the art can make various changes and improvements to the concepts disclosed above, but these changes and improvements all belong to the protection scope of the present disclosure. The description of the above embodiments is exemplary rather than limiting, and the protection scope of the present disclosure is defined by the appended claims.

[0089] The specification and illustrations of the embodiments described herein are intended to provide a general understanding of the structure of the various embodiments. The specification and illustrations are not intended to serve as an exhaustive and comprehensive description of all of the elements and features of apparatus and systems that use the structures or methods described herein. Certain features, that are for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in a sub combination. Further, reference to values stated in ranges includes each and every value within that range. Many other embodiments may be apparent to skilled artisans only after reading this specification. Other embodiments may be used and derived from the disclosure, such that a structural substitution, logical substitution, or another change may be made without departing from the scope of the disclosure. Accordingly, the disclosure is to be regarded as illustrative rather than restrictive.

[0090] The description in combination with the figures is provided to assist in understanding the teachings disclosed herein, is provided to assist in describing the teachings, and should not be interpreted as a limitation on the scope or applicability of the teachings. However, other teachings can certainly be used in this application.

[0091] As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having" or any other variation thereof, are intended to cover a non-exclusive inclusion. For example, a method, article, or apparatus that comprises a list of features is not necessarily limited only to those features but may include other features not expressly listed or inherent to such method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive-or and not to an exclusive-or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). [0092] Also, the use of "a" or "an" is employed to describe elements and components described herein. This is done merely for convenience and to give a general sense of the scope of the disclosure. This description should be read to include one or at least one and the singular also includes the plural, or vice versa, unless it is clear that it is meant otherwise. For example, when a single item is described herein, more than one item may be used in place of a single item.

Similarly, where more than one item is described herein, a single item may be substituted for that more than one item.

[0093] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. The materials, methods, and examples are illustrative only and not intended to be limiting. To the extent that certain details regarding specific materials and processing acts are not described, such details may include conventional approaches, which may be found in reference books and other sources within the manufacturing arts.

[0094] While aspects of the present disclosure have been particularly shown and described with reference to the embodiments above, it will be understood by those skilled in the art that various additional embodiments may be contemplated by the modification of the disclosed machines, systems and methods without departing from the spirit and scope of what is disclosed. Such embodiments should be understood to fall within the scope of the present disclosure as determined based upon the claims and any equivalents thereof.