Hydrogen energy storage system for solid-gas coupling hydrogen storage and operation method of hydrogen energy storage system

Abstract

The invention belongs to the technical field of hydrogen energy storage, and provides a solid-gas coupled hydrogen energy storage system and an operation method thereof. The solid-gas coupled hydrogen energy storage system comprises an electrolytic cell, a fuel cell, a solid-gas coupled hydrogen storage system and a heat exchange fluid circulating system, the electrolytic tank is used for electrolyzing water to produce hydrogen, in the hydrogen storage process, generated hydrogen enters the metal hydride hydrogen storage device to be stored, and unstored hydrogen enters the high-pressure gaseous hydrogen storage device to be stored; in the hydrogen release process, the high-pressure gaseous hydrogen storage device is used for releasing hydrogen, the released hydrogen preferentially enters the fuel cell and assists the heat exchange fluid circulation system in cooling and heat dissipation, and then the hydrogen enters the metal hydride hydrogen storage device to heat the metal hydride so as to release hydrogen in the metal hydride; hydrogen released by the high-pressure gaseous hydrogen storage device and hydrogen released by the metal hydride hydrogen storage device are mixed and then enter the fuel cell for power generation.

Description

Technical Field

[0001] The present invention belongs to the technical field of hydrogen energy storage, and in particular relates to a hydrogen energy storage system of solid-gas coupled hydrogen storage and an operation method thereof. Background Art

[0002] The statements in this section merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Hydrogen energy storage has the advantages of long storage time and large scale, and is of great significance for solving the problem of renewable energy consumption and alleviating peak-valley electricity differences. The existing hydrogen storage energy supply system mostly uses high-pressure gaseous hydrogen storage, which has high hydrogen storage pressure and low hydrogen storage density. There are problems such as low hydrogen storage efficiency, high cost and great safety risks. Solid-state hydrogen storage solutions, especially solid-state hydrogen storage based on metal hydrides, have the advantages of low hydrogen storage pressure, high volume hydrogen storage density and high hydrogen storage safety, and low parasitic power consumption, but metal hydrides have the disadvantage of low thermal conductivity, and their hydrogen storage / desorption rates are easily limited by reaction exothermic / absorption.

[0004] Therefore, a single hydrogen storage method has different defects in terms of volumetric hydrogen storage density, energy consumption, dynamic response characteristics and system volume. However, high-pressure gaseous hydrogen storage and metal hydride solid hydrogen storage have excellent matching properties, and the new solid-gas coupling hydrogen storage method combining the two can solve these problems to a certain extent.

[0005] Existing solid-state hydrogen storage devices mainly accelerate the heat transfer rate during the storage and desorption of hydrogen by embedding heat exchange tube bundles, finned heat exchange tubes, and specially designed heat exchange channels in the bed. However, although these embedded heat exchangers can effectively exchange heat with adjacent metal hydride areas, due to the low thermal conductivity of the metal hydride itself, the reaction rate of reactants far away from the heat exchange surface is limited, resulting in a prolonged hydrogen storage / desorption cycle, which limits the large-scale commercial application of metal hydride hydrogen storage technology. The hydrogen released by existing gaseous hydrogen storage devices is generally directly passed into hydrogen-using equipment, which means that the pressure energy of high-pressure hydrogen cannot be effectively utilized during the entire desorption process, resulting in a large energy loss. In addition, the power generation efficiency of the fuel cell system is about 50%, and there is obvious heat dissipation, which significantly reduces the energy utilization efficiency. Summary of the invention

[0006] In order to solve at least one technical problem existing in the above-mentioned background technology, the present invention provides a solid-gas coupled hydrogen energy storage system and an operation method thereof. The system is an electric-hydrogen-thermal hydrogen energy system based on solid-gas coupled hydrogen storage and fuel cells, which can reduce the system's requirements for the heat exchange capacity of the hydrogen storage device, and achieve a comprehensive improvement in the system's volumetric hydrogen storage density, hydrogen storage capacity, parasitic power consumption and hydrogen storage / desorption rate.

[0007] In order to achieve the above object, the present invention adopts the following technical solution:

[0008] A first aspect of the present invention provides a solid-gas coupled hydrogen energy storage system.

[0009] A solid-gas coupled hydrogen energy storage system, comprising an electrolyzer, a fuel cell, a solid-gas coupled hydrogen storage system and a heat exchange fluid circulation system; the solid-gas coupled hydrogen storage system comprises a metal hydride hydrogen storage device and a high-pressure gaseous hydrogen storage device; the heat exchange fluid circulation system is connected to the fuel cell and is used to absorb the heat generated during the power generation process of the fuel cell;

[0010] The electrolyzer is used to electrolyze water to produce hydrogen. During the hydrogen storage process, the generated hydrogen is preferentially stored in the metal hydride hydrogen storage device, and the unstored hydrogen is stored in the high-pressure gaseous hydrogen storage device;

[0011] During the hydrogen release process, the high-pressure gaseous hydrogen storage device is used to release hydrogen. The released hydrogen first enters the fuel cell and assists the heat exchange fluid circulation system to exchange heat for the fuel cell, and then enters the metal hydride hydrogen storage device to heat the metal hydride to release the hydrogen therein, so that the hydrogen released by the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device are mixed and then enter the fuel cell to generate electricity.

[0012] As an embodiment, the electrolyzer and the high-pressure gaseous hydrogen storage device, the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device, the high-pressure gaseous hydrogen storage device and the fuel cell, and the metal hydride hydrogen storage device and the fuel cell are connected through hydrogen pipelines.

[0013] As an implementation mode, the hydrogen pipeline is provided with a hydrogen compressor, a hydrogen valve and a hydrogen buffer tank.

[0014] As an embodiment, the heat exchange fluid circulation system includes a heat exchange fluid circulation pipeline, and a liquid bath, a circulation pump and a heat exchange fluid valve arranged on the heat exchange fluid circulation pipeline.

[0015] As an embodiment, the metal hydride hydrogen storage device is a rectangular parallelepiped and is placed horizontally, the hydrogen inlet and outlet of the metal hydride hydrogen storage device are respectively located on both sides of the metal hydride hydrogen storage device, and there is a hydrogen buffer zone between the hydrogen inlet and outlet and the metal hydride area.

[0016] As an embodiment, the metal hydride area is arranged between the hydrogen inlet buffer zone and the outlet buffer zone; hydrogen flows from the hydrogen inlet through the hydrogen inlet buffer zone into the metal hydride bed of the metal hydride hydrogen storage device, and exchanges heat with the metal hydride therein to cool or heat the metal hydride bed.

[0017] As an embodiment, the electrolytic cell is an alkaline electrolytic cell, a proton exchange membrane electrolytic cell and a polymer electrolyte membrane electrolytic cell, or a combination of several of them.

[0018] As an embodiment, the metal hydride material in the metal hydride hydrogen storage device includes one or a combination of LaNi5, Mg, Mg2Ni, FeTi.

[0019] As an embodiment, the fuel cell is a proton exchange membrane fuel cell, a phosphoric acid fuel cell, an alkaline fuel cell, or a combination of several thereof.

[0020] A second aspect of the present invention provides a method for operating a solid-gas coupled hydrogen energy storage system.

[0021] A method for operating a solid-gas coupled hydrogen energy storage system, comprising:

[0022] In the hydrogen storage process, the electrolyzer is driven by electricity to electrolyze water to produce hydrogen. After the hydrogen is cooled, it enters the metal hydride hydrogen storage device and flows into the metal hydride area from the side hydrogen buffer of the metal hydride hydrogen storage device. Part of the hydrogen is adsorbed in the metal hydride area. The metal hydride hydrogen storage releases heat, which is absorbed by the remaining unabsorbed hydrogen. The heat-absorbing hydrogen flows out of the metal hydride hydrogen storage device through the hydrogen outlet and finally enters the high-pressure gaseous hydrogen storage device for storage. When the metal hydride hydrogen storage device is saturated, the inlet of the metal hydride hydrogen storage device is closed, and the hydrogen is pressurized and enters the high-pressure gaseous hydrogen storage device for storage through a bypass.

[0023] During the hydrogen release process, the high-pressure gaseous hydrogen storage device releases hydrogen, and the pressure energy of the high-pressure hydrogen is used as the driving force for the flow of hydrogen. The released low-pressure hydrogen at room temperature enters the fuel cell first. After the hydrogen absorbs heat at the fuel cell, it flows in through the hydrogen inlet on the side of the metal hydride hydrogen storage device. The hot hydrogen after absorbing heat heats the metal hydride bed through convection heat transfer and heat conduction, so that the metal hydride therein releases hydrogen. The hydrogen released by the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device are mixed and then enter the fuel cell to generate electricity. When the metal hydride hydrogen storage device completes hydrogen release, the hydrogen in the high-pressure hydrogen storage device directly flows into the fuel cell to generate electricity.

[0024] The beneficial effects of the present invention are:

[0025] (1) The metal hydride hydrogen storage device of the hydrogen energy storage system proposed in the present invention adopts low-temperature / high-temperature hydrogen to pass through the metal hydride bed, which can cool / heat the metal hydride more evenly, effectively reducing the limitation of the low thermal conductivity of the bed on the hydrogen storage performance, and significantly improving the hydrogen storage / dehydrogenation performance of the hydrogen storage device. At the same time, it simplifies the heat exchange fluid circulation of the metal hydride and reduces the energy consumption of the heat exchange system.

[0026] (2) In the hydrogen energy storage system proposed by the present invention, during the hydrogen discharge process, hydrogen flows into the fuel cell cooling circuit to assist the heat exchange fluid in cooling the dissipated heat, and enters the hydrogen storage device to heat the metal hydride bed, thereby effectively utilizing the heat dissipated by the fuel cell, achieving a reduction in the energy consumption of the heat exchange system and an improvement in the energy utilization efficiency of the hydrogen energy system.

[0027] (3) The hydrogen energy storage system proposed in the present invention utilizes the pressure energy of the high-pressure hydrogen in the high-pressure gaseous hydrogen storage device during the hydrogen release process to drive the hydrogen to absorb heat at the fuel cell and enter the hydrogen storage device to heat the metal hydride bed, thereby effectively utilizing the hydrogen pressure energy of the high-pressure gaseous hydrogen storage and achieving a reduction in parasitic power consumption in the hydrogen storage / dehydrogenation cycle.

[0028] Advantages of additional aspects of the present invention will be given in part in the following description, and in part will become obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings in the specification, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0030] Figure 1 This is a schematic structural diagram of a solid-gas coupled hydrogen energy storage system according to an embodiment of the present invention;

[0031] FIG2( a ) is a front view of a metal hydride hydrogen storage device according to an embodiment of the present invention;

[0032] FIG2( b ) is a left side view of the metal hydride hydrogen storage device according to an embodiment of the present invention;

[0033] FIG2( c ) is a top view of a metal hydride hydrogen storage device according to an embodiment of the present invention;

[0034] FIG2( d ) is a schematic diagram of the three-dimensional structure of a metal hydride hydrogen storage device according to an embodiment of the present invention;

[0035] FIG3( a ) is a cross-sectional view taken along line AA of FIG2( a );

[0036] FIG3( b ) is a BB cross-sectional view of FIG2( a );

[0037] FIG3( c ) is a CC cross-sectional view of FIG2( c ).

[0038] in:

[0039] 1-power generation system, 2-first hydrogen valve, 3-high-pressure gaseous hydrogen storage device, 4-second hydrogen valve, 5-third hydrogen valve, 6-fourth hydrogen valve, 7-metal hydride hydrogen storage device, 8-fifth hydrogen valve, 9-filter, 10-circulation pump, 11-liquid bath, 12-heat exchange fluid valve, 13-sixth hydrogen valve, 14-fuel cell, 15-seventh hydrogen valve, 16-hydrogen compressor, 17-electrolyzer, 18-outer shell, 19-hydrogen inlet, 20-hydrogen outlet, 21-hydrogen inlet buffer zone, 22-metal hydride area, 23-hydrogen outlet buffer zone. DETAILED DESCRIPTION

[0040] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0041] It should be noted that the following detailed descriptions are all illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0042] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0043] According to the background technology, there is an urgent need to develop a hydrogen energy storage system coupled with a high-pressure gaseous hydrogen storage device and a metal hydride solid hydrogen storage device and an operating method thereof, so that the system can simultaneously have the advantages of fast hydrogen release rate of the high-pressure gaseous hydrogen storage device and low parasitic power consumption and high safety of the metal hydride hydrogen storage device, and can utilize the heat dissipated by the fuel cell system to reduce the energy consumption of the heat exchange fluid circulation, thereby achieving a comprehensive improvement in the system's volume hydrogen storage density, hydrogen storage capacity, parasitic power consumption and hydrogen storage / release rate, thereby promoting the scale and commercialization of metal hydrogen storage reactors and promoting the practical application of hydrogen energy storage systems in the field of power grid peak regulation. Figure 1 Schematic diagram of the structure of a solid-gas coupled hydrogen energy storage system according to an embodiment of the present invention.

[0044] according to Figure 1 The embodiment of the present invention provides a solid-gas coupled hydrogen energy storage system, comprising an electrolyzer 17, a high-pressure gaseous hydrogen storage device 3, a metal hydride hydrogen storage device 7, a fuel cell 14 and a heat exchange fluid circulation system; the heat exchange fluid circulation system is connected to the fuel cell 14, and is used to absorb the heat generated during the power generation process of the fuel cell 14;

[0045] The electrolyzer 17 is used to utilize the electric energy generated by the power generation system 1 to electrolyze water to produce hydrogen. During the hydrogen storage process, the generated hydrogen is preferentially stored in the metal hydride hydrogen storage device 7, and the unstored hydrogen is stored in the high-pressure gaseous hydrogen storage device 3;

[0046] During the hydrogen release process, the high-pressure gaseous hydrogen storage device 3 is used to release hydrogen. The released hydrogen first enters the fuel cell 14 and assists the heat exchange fluid circulation system to cool the consumed heat, and then enters the metal hydride hydrogen storage device 7 to heat the metal hydride to release the hydrogen therein, so that the hydrogen released by the high-pressure gaseous hydrogen storage device 3 and the metal hydride hydrogen storage device 7 are mixed and then enter the fuel cell to generate electricity.

[0047] Specifically, the high-pressure gaseous hydrogen storage device 3 can be implemented by at least one high-pressure gaseous hydrogen storage bottle.

[0048] In this embodiment, the electrolyzer 17 and the high-pressure gaseous hydrogen storage device 3, the high-pressure gaseous hydrogen storage device 3 and the metal hydride hydrogen storage device 7, the high-pressure gaseous hydrogen storage device 3 and the fuel cell 14, and the metal hydride hydrogen storage device 7 and the fuel cell 14 are connected through hydrogen pipelines.

[0049] In this embodiment, the hydrogen pipeline is provided with a hydrogen compressor 16, a hydrogen valve and a hydrogen buffer tank. The hydrogen valve includes a first hydrogen valve 2, a second hydrogen valve 4, a third hydrogen valve 5, a fourth hydrogen valve 6, a fifth hydrogen valve 8, a sixth hydrogen valve 13 and a seventh hydrogen valve 15.

[0050] In the specific implementation process, the heat exchange fluid circulation system includes a heat exchange fluid circulation pipeline, and a liquid bath 11, a circulation pump 10 and a heat exchange fluid valve 12 arranged on the heat exchange fluid circulation pipeline.

[0051] like Figure 2(a)-Figure 2(d) and Figure 3(a)-3(c) As shown, the outer shell 18 of the metal hydride hydrogen storage device 7 is a rectangular parallelepiped and is placed horizontally. The hydrogen inlet 19 and the hydrogen outlet 20 of the metal hydride hydrogen storage device 7 are respectively located on both sides of the metal hydride hydrogen storage device 7. There are hydrogen buffer zones between the hydrogen inlet 19 and the hydrogen outlet 20 and the metal hydride area 22, which are the hydrogen inlet buffer zone 21 and the hydrogen outlet buffer zone 23.

[0052] The metal hydride region 22 is arranged between the hydrogen inlet buffer zone 21 and the hydrogen outlet buffer zone 23; hydrogen flows from the hydrogen inlet 19 through the hydrogen inlet buffer zone 21 into the metal hydride bed of the metal hydride hydrogen storage device 7, and exchanges heat with the metal hydride therein to cool or heat the metal hydride bed.

[0053] In a specific implementation process, the electrolytic cell 17 is an alkaline electrolytic cell, a proton exchange membrane electrolytic cell and a polymer electrolyte membrane electrolytic cell, or a combination of several of them.

[0054] In the specific implementation process, the metal hydride material in the metal hydride hydrogen storage device 7 includes but is not limited to LaNi5, Mg, Mg2Ni, FeTi, or a combination of several of them.

[0055] In a specific implementation process, the fuel cell 14 is a proton exchange membrane fuel cell, a phosphoric acid fuel cell, an alkaline fuel cell, etc., or a combination of several of them.

[0056] like Figure 1 An operating method of a solid-gas coupled hydrogen energy storage system is shown, comprising:

[0057] In the hydrogen storage process, the electrolyzer is driven by electricity to electrolyze water to produce hydrogen. After the hydrogen is cooled, it enters the metal hydride hydrogen storage device and flows into the metal hydride area from the side hydrogen buffer of the metal hydride hydrogen storage device. Part of the hydrogen is adsorbed in the metal hydride area. The metal hydride hydrogen storage releases heat, which is absorbed by the remaining unabsorbed hydrogen. The heat-absorbing hydrogen flows out of the metal hydride hydrogen storage device through the hydrogen outlet and finally enters the high-pressure gaseous hydrogen storage device for storage. When the metal hydride hydrogen storage device is saturated, the inlet of the metal hydride hydrogen storage device is closed, and the hydrogen is pressurized and enters the high-pressure gaseous hydrogen storage device for storage through a bypass.

[0058] During the hydrogen release process, the high-pressure gaseous hydrogen storage device releases hydrogen, with the pressure energy of the high-pressure hydrogen being the driving force for the flow of hydrogen. The released low-pressure hydrogen at room temperature enters the fuel cell first. After the hydrogen absorbs heat at the fuel cell, it flows in through the hydrogen inlet on the side of the metal hydride hydrogen storage device. The hydrogen after absorbing heat heats the metal hydride bed through convection heat transfer and heat conduction, causing the metal hydride therein to release hydrogen. The hydrogen released by the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device are mixed and then enter the fuel cell to generate electricity. When the metal hydride hydrogen storage device completes hydrogen release, the hydrogen in the high-pressure hydrogen storage device directly flows into the fuel cell to generate electricity.

[0059] Specifically, the operating principle of the solid-gas coupled hydrogen energy storage system is:

[0060] (1) During the hydrogen storage process, the first hydrogen valve 2, the third hydrogen valve 5, the seventh hydrogen valve 15, and the sixth hydrogen valve 13 are closed, and the power generation system (e.g., Figure 1The electricity from the wind power generation and the residual power source in the photovoltaic power generation system) drives the electrolyzer 17 to electrolyze water to produce hydrogen, and the hydrogen is pressurized by the hydrogen compressor 16 and enters the metal hydride hydrogen storage device 7. The hydrogen flows into the metal hydride area 22 through the hydrogen buffer area 21 on the side of the metal hydride hydrogen storage device 7, and part of the hydrogen is adsorbed in this area. The heat released by the metal hydride hydrogen storage is transferred to the unadsorbed hydrogen through convection heat transfer and heat conduction, and is carried away from the metal hydride hydrogen storage device 7 by the hydrogen flow through the hydrogen outlet 20, and finally enters the high-pressure gaseous hydrogen storage device 3 for storage through the fifth hydrogen valve 8. When the metal hydride hydrogen storage device 7 is saturated, the inlet hydrogen valve 4 and the outlet fifth hydrogen valve 8 are closed, the first hydrogen valve 2 is opened, the pressure of the hydrogen compressor 16 is increased, and the high-pressure hydrogen enters the high-pressure gaseous hydrogen storage device 3 for storage through the bypass.

[0061] (2) During the hydrogen release process, the first hydrogen valve 2, the second hydrogen valve 4, the fourth hydrogen valve 6, and the fifth hydrogen valve 8 are closed, and the high-pressure gaseous hydrogen storage device 3 releases hydrogen. The pressure energy of the high-pressure hydrogen is used as the driving force for the flow of hydrogen. The released low-pressure hydrogen at room temperature enters the cooling circuit of the fuel cell 14 through the seventh hydrogen valve 15 to assist the heat exchange fluid circulation system in cooling the heat consumed by the fuel cell 14. After the hydrogen absorbs heat at the fuel cell, it flows in through the third hydrogen valve 5 through the side hydrogen inlet 19 of the metal hydride hydrogen storage device, heats the metal hydride bed in the form of convection heat exchange and heat conduction, and causes the metal hydride to release hydrogen. The hydrogen released by the two hydrogen storage devices is mixed and enters the fuel cell 14 through the sixth hydrogen valve 13 to generate electricity. After the metal hydride hydrogen storage device 7 completes the hydrogen release, the sixth hydrogen valve 13 is closed, the fourth hydrogen valve 6 is opened, and the hydrogen in the high-pressure hydrogen storage device 3 flows into the fuel cell 14 through the fourth hydrogen valve 6 to generate electricity.

[0062] The metal hydride hydrogen storage device of the hydrogen energy storage system proposed in the present invention adopts low-temperature / high-temperature hydrogen to pass through the metal hydride bed, which can cool / heat the metal hydride more evenly, effectively reducing the limitation of the low thermal conductivity of the bed on the hydrogen storage performance, and significantly improving the hydrogen storage / dehydrogenation performance of the hydrogen storage device. At the same time, it simplifies the heat exchange fluid circulation of the metal hydride and reduces the energy consumption of the heat exchange system.

[0063] In the hydrogen energy storage system proposed by the present invention, during the hydrogen discharge process, hydrogen flows into the fuel cell cooling circuit to assist the heat exchange fluid in cooling the dissipated heat, and enters the hydrogen storage device to heat the metal hydride bed, thereby effectively utilizing the heat dissipated by the fuel cell, achieving a reduction in the energy consumption of the heat exchange system and an improvement in the energy utilization efficiency of the hydrogen energy system.

[0064] The hydrogen energy storage system proposed in the present invention utilizes the pressure energy of high-pressure hydrogen in the high-pressure gaseous hydrogen storage device to drive the hydrogen to absorb heat at the fuel cell and enter the hydrogen storage device to heat the metal hydride bed during the hydrogen release process, thereby effectively utilizing the hydrogen pressure energy of the high-pressure gaseous hydrogen storage and achieving a reduction in parasitic power consumption in the hydrogen storage / dehydrogenation cycle.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A solid-gas coupled hydrogen energy storage system, characterized in that: It includes an electrolyzer, a high-pressure gaseous hydrogen storage device, a metal hydride hydrogen storage device, a fuel cell and a heat exchange fluid circulation system; the heat exchange fluid circulation system is connected to the fuel cell and is used to absorb the heat generated during the power generation process of the fuel cell; The electrolyzer is used to electrolyze water to produce hydrogen. During the hydrogen storage process, the generated hydrogen enters the metal hydride hydrogen storage device for storage, and the unstored hydrogen enters the high-pressure gaseous hydrogen storage device for storage; During the hydrogen release process, the high-pressure gaseous hydrogen storage device is used to release hydrogen. The released hydrogen first enters the fuel cell and assists the heat exchange fluid circulation system to cool the consumed heat, and then enters the metal hydride hydrogen storage device to heat the metal hydride to release the hydrogen therein, so that the hydrogen released by the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device are mixed and then enter the fuel cell to generate electricity.

2. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The electrolyzer and the high-pressure gaseous hydrogen storage device, the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device, the high-pressure gaseous hydrogen storage device and the fuel cell, and the metal hydride hydrogen storage device and the fuel cell are connected through hydrogen pipelines.

3. The solid-gas coupled hydrogen energy storage system according to claim 2, characterized in that: The hydrogen pipeline is provided with a hydrogen compressor, a hydrogen valve and a hydrogen buffer tank.

4. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The heat exchange fluid circulation system comprises a heat exchange fluid circulation pipeline, and a liquid bath, a circulation pump and a heat exchange fluid valve arranged on the heat exchange fluid circulation pipeline.

5. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The metal hydride hydrogen storage device is a rectangular parallelepiped and is placed horizontally. The hydrogen inlet and outlet of the metal hydride hydrogen storage device are respectively located on both sides of the metal hydride hydrogen storage device, and there is a hydrogen buffer zone between the hydrogen inlet and outlet and the metal hydride area.

6. The solid-gas coupled hydrogen energy storage system according to claim 5, characterized in that: The metal hydride area is arranged between the hydrogen inlet buffer zone and the outlet buffer zone; hydrogen flows from the hydrogen inlet through the hydrogen inlet buffer zone into the metal hydride bed of the metal hydride hydrogen storage device and performs heat exchange with the metal hydride therein to cool or heat the metal hydride bed.

7. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The electrolytic cell is an alkaline electrolytic cell, a proton exchange membrane electrolytic cell and a polymer electrolyte membrane electrolytic cell, or a combination of several of them.

8. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The metal hydride material in the metal hydride hydrogen storage device includes one or a combination of LaNi5, Mg, Mg2Ni, FeTi.

9. The solid-gas coupled hydrogen energy storage system according to claim 1, characterized in that: The fuel cell is a proton exchange membrane fuel cell, a phosphoric acid fuel cell, an alkaline fuel cell, or a combination of the two.

10. An operating method of a solid-gas coupled hydrogen energy storage system according to any one of claims 1 to 9, characterized in that: include: In the hydrogen storage process, the electrolyzer is driven by electricity to electrolyze water to produce hydrogen. After the hydrogen is cooled, it enters the metal hydride hydrogen storage device and flows into the metal hydride area from the side hydrogen buffer of the metal hydride hydrogen storage device. Part of the hydrogen is adsorbed in the metal hydride area. The metal hydride hydrogen storage releases heat, which is absorbed by the remaining unabsorbed hydrogen. The heat-absorbing hydrogen flows out of the metal hydride hydrogen storage device through the hydrogen outlet and finally enters the high-pressure gaseous hydrogen storage device for storage. When the metal hydride hydrogen storage device is saturated, the inlet of the metal hydride hydrogen storage device is closed, and the hydrogen is pressurized and enters the high-pressure gaseous hydrogen storage device for storage through a bypass. During the hydrogen release process, the high-pressure gaseous hydrogen storage device releases hydrogen, and the pressure energy of the high-pressure hydrogen is used as the driving force for the flow of hydrogen. The released low-pressure hydrogen at room temperature enters the fuel cell first. After the hydrogen absorbs heat at the fuel cell, it flows in through the hydrogen inlet on the side of the metal hydride hydrogen storage device. The hot hydrogen after absorbing heat heats the metal hydride bed through convection heat transfer and heat conduction, so that the metal hydride therein releases hydrogen. The hydrogen released by the high-pressure gaseous hydrogen storage device and the metal hydride hydrogen storage device are mixed and then enter the fuel cell to generate electricity. When the metal hydride hydrogen storage device completes hydrogen release, the hydrogen in the high-pressure hydrogen storage device directly flows into the fuel cell to generate electricity.

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