An energy storage device for hydrogen production by electrolytic water in conjunction with low temperature and its energy storage method

Abstract

An energy storage device for hydrogen production by electrolytic water in conjunction with low temperature and its energy storage method for solving the problem of discontinuous photovoltaic resources and the conflicting requirement of continuous hydrogen production, wherein the device comprises a pre-cooled hydrogen liquefaction system with liquid nitrogen, a liquid hydrogen-liquid nitrogen heat exchange system, a cold energy storage system and a cold energy utilization system of an air separation device, wherein the systems in the present invention are highly coupled, wherein the maximum utilization of renewable photovoltaic energy can be realized through the form of hydrogen storage and the energy consumption costs for the production and use of green hydrogen can be effectively reduced while realizing efficient energy storage and peak shaving.This will result in energy savings and offers good promotion prospects.

Description

Technical area

[0001] The invention relates to the field of solar renewable energy generation and green electricity water electrolysis for hydrogen production, energy storage by hydrogen liquefaction, hydrogen energy, and in particular to an energy storage device for hydrogen production by electrolytic water in conjunction with low temperature and its energy storage method. Background technology

[0002] Renewable energy, represented by solar power, is highly influenced by natural environmental factors (season, weather), and its energy input and output in the electricity generation process cannot be precisely controlled like fossil fuels. It is characterized by large fluctuations, discontinuities, randomness, and uncontrollability, making it difficult to connect and utilize directly in the grid. This has led to a widespread abandonment of photovoltaic power generation. Therefore, the question of how to effectively suppress photovoltaic power fluctuations and increase its consumption capacity has become one of the most significant technical bottlenecks hindering the large-scale development of photovoltaics.As energy buffers, energy storage systems can effectively suppress fluctuations in photovoltaic power and reduce the need to forgo electricity generation from photovoltaics and generated but unused electricity, and will play an increasingly important role in promoting the rational use of renewable energies.

[0003] Due to the excellent energy density, energy efficiency, and cleanliness of hydrogen energy, as well as the fact that electricity, nuclear power, solar, wind, and hydropower can be converted into hydrogen for storage, transport, or direct use, hydrogen is considered the best carbon-neutral energy carrier and will play a key role in decarbonization. Hydrogen can be produced on a large scale through the reforming of natural gas or fossil fuels, the purification of hydrogen from industrial byproducts, the electrolysis of renewable electricity, and other methods. "Eco-hydrogen," produced through the electrolysis of renewable energy sources such as solar power, is the ultimate goal for future energy sources, as it produces no or very low carbon emissions.The use of hydrogen as an energy carrier for the central processing of renewable resources has become established worldwide, promoting the joint development of renewable resources and hydrogen energy with a broad market for its use. Most hydrogen energy is currently used in traditional industries such as oil refining, ammonia synthesis, and methanol production, while the supply of raw hydrogen produced by electrolysis using renewable energy sources like solar power has a significant impact on downstream processes. Therefore, the use of renewable energy sources like solar power, which exhibit market volatility and large fluctuations, to generate a continuous supply of "eco-hydrogen" is a hot topic and a challenging area of ​​research.

[0004] To ensure a continuous supply of "eco-hydrogen," a sufficient quantity of hydrogen can be produced via water electrolysis using the renewable energy generated during this phase, provided the renewable energy system has sufficient capacity (i.e., sufficient solar radiation). This hydrogen can then be supplied as raw gas to downstream factories and businesses, even if a certain hydrogen surplus remains. To fully utilize this surplus hydrogen, it can be stored as an energy source for future energy supply during periods of energy scarcity. Current hydrogen storage technologies include high-pressure gaseous hydrogen storage, low-temperature liquid hydrogen storage, organic liquid hydrogen storage, and solid-state hydrogen storage.Liquid hydrogen storage is the more suitable form of hydrogen storage for the need for large-volume, long-distance storage due to its storage density and high storage and transport efficiency. A hydrogen liquefaction system is used to liquefy the excess hydrogen from this photoelectric hydrogen production via eco-electrolysis and then feed it into a liquid hydrogen storage tank. If the renewable energy power generation system does not produce enough electricity due to environmental changes—for example, if the solar power plant cannot supply the electricity required for hydrogen production via eco-electrolysis at night—the liquid hydrogen in the storage tank is simply vaporized and fed into the downstream process pipeline network to ensure a continuous supply of raw hydrogen to the downstream plant.However, since hydrogen has an extremely low boiling point (20 K), energy consumption for liquid cooling is high. The question of how to reduce energy consumption in industrial hydrogen storage is key to hydrogen storage and to the rational use and development of renewable resources such as solar energy through "eco-hydrogen". Contents of the invention

[0005] The technical problem to be solved by the present invention is to provide an energy storage device for hydrogen production by electrolytic water in conjunction with low temperatures, and its energy storage method, in order to solve the problem of discontinuous photovoltaic resources and the conflicting requirement for continuous hydrogen production. Maximum utilization of renewable photovoltaic energy is achieved through the storage of liquid hydrogen, and efficient energy storage and peak load management are achieved, while reducing the energy costs of producing and using the renewable hydrogen to achieve the aforementioned objectives. The following technologies are used in the present invention: an energy storage device for hydrogen production by electrolytic water in conjunction with low temperatures,wherein the device comprises a pre-cooled liquid nitrogen hydrogen liquefaction system, a liquid hydrogen-liquid nitrogen heat exchange system, a cold energy storage system, and a cold energy utilization system of an air separation device, wherein the pre-cooled liquid nitrogen hydrogen liquefaction system comprises a liquid nitrogen inlet system, a nitrogen outlet system, a liquid hydrogen outlet system, and a hydrogen liquefaction system, each system being connected by piping and controlled by valves, wherein the liquid hydrogen-liquid nitrogen heat exchange system comprises a liquid hydrogen storage tank, a liquid hydrogen pump, a liquid hydrogen-liquid nitrogen heat exchanger, and a liquid nitrogen storage tank, each system being connected by piping and controlled by valves for evaporating liquid hydrogen and liquefying nitrogen.wherein the liquid hydrogen inlet of the liquid hydrogen storage tank is connected to the liquid hydrogen outlet system of the pre-cooled hydrogen liquefaction system with liquid nitrogen, the liquid hydrogen inlet of the liquid hydrogen pump is connected to the liquid hydrogen outlet of the liquid hydrogen storage tank, the liquid hydrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the liquid hydrogen outlet of the liquid hydrogen pump, the liquid nitrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the nitrogen outlet of the nitrogen outlet system of the air separation unit of the cold energy utilization system, the liquid nitrogen outlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the liquid nitrogen inlet of the liquid nitrogen storage tank,The liquid nitrogen outlet of the liquid nitrogen storage tank is connected to the inlet of the liquid nitrogen inlet system of the pre-cooled hydrogen liquefaction system with liquid nitrogen.

[0006] Preferably, the cold energy storage system comprises a heat exchanger for hydrogen refrigerant carrier, a refrigerant carrier pump, a heat exchanger for refrigerant carrier cold energy storage, a refrigerant storage tank, and a cold energy storage tank, wherein each system is connected by piping and controlled by valves for reheating hydrogen and storing cold energy, wherein the hydrogen inlet of the heat exchanger for hydrogen refrigerant carrier is connected to the hydrogen outlet of the heat exchanger for liquid hydrogen / liquid nitrogen, the refrigerant carrier outlet of the heat exchanger for hydrogen refrigerant carrier is connected to the refrigerant carrier inlet of the refrigerant carrier pump, and the refrigerant carrier outlet of the refrigerant carrier pump is connected to the refrigerant carrier inlet of the heat exchanger for refrigerant carrier cold energy storage.The refrigerant carrier outlet of the heat exchanger for refrigerant carrier cold energy storage is connected to the refrigerant carrier inlet of the heat exchanger for hydrogen refrigerant carrier, the water outlet of the heat exchanger for refrigerant carrier cold energy storage is connected to the inlet of the cold energy storage tank, and the refrigerant storage tank is connected to the refrigerant carrier inlet of the refrigerant carrier pump by pipes and valves.

[0007] Preferably, the cold energy utilization system of an air separation device comprises a circulating water system, a water cooling tower, a nitrogen outlet system of the air separation system, and a cold water inlet system of the air separation system, wherein each system is interconnected by piping and controlled by valves, the outlet of the circulating water system being connected to the water inlet of the heat exchanger for the refrigerant-carrier cold energy storage tank, the outlet of the cold energy storage tank being connected to the upper inlet of the water cooling tower, the outlet of the nitrogen outlet system being connected to the lower inlet of the water cooling tower, and the lower outlet of the water cooling tower being connected to the inlet of the cold water inlet system of the air separation system.

[0008] Preferably, the heat exchanger for liquid hydrogen-liquid nitrogen, the heat exchanger for hydrogen-refrigerant carrier and the heat exchanger for refrigerant carrier-cold energy storage are tube heat exchangers or plate heat exchangers.

[0009] Preferably, the water cooling tower is a packed-bed tower.

[0010] An energy storage method for application to the energy storage device comprises the following steps; Step 1: if there is an excess of photoelectric eco-water electrolysis to hydrogen, the excess hydrogen can be liquefied by a hydrogen liquefaction system, using liquid nitrogen as a pre-cooling source for the hydrogen liquefaction, the liquefied liquid hydrogen being directed to a liquid hydrogen storage tank for storage, the evaporated nitrogen from the nitrogen outlet system being heated to room temperature is directed through piping to the lower part of the water cooling tower and sprayed through the low-temperature water in the upper part of the water cooling tower from the cold energy storage tank, further cooling the low-temperature water, which is beneficial to the subsequent air separation process and reduces the energy consumption of the air separation system.

[0011] Step 2: If the renewable energy power generation system, such as photovoltaics, is insufficient to produce hydrogen from eco-electrolyte water due to environmental changes, such as weakening sunlight, the liquid hydrogen stored in the liquid hydrogen storage tank is pressurized by the liquid hydrogen pump and then enters the liquid hydrogen-liquid nitrogen heat exchanger to evaporate and reheat. It then enters the hydrogen-refrigerant carrier heat exchanger to reheat and obtain room-temperature hydrogen, which is used to supplement the insufficient hydrogen production from eco-electrolyte water. The room-temperature nitrogen acts as a heat source for the evaporation and reheating of the liquid hydrogen from the nitrogen output system into the liquid hydrogen-liquid nitrogen heat exchanger.which is liquefied and condensed to liquid nitrogen and then enters the liquid nitrogen storage tank, and can also be used as a partial supplement to pre-cool the liquid nitrogen during the liquefaction of the hydrogen, wherein the refrigerant carrier enters the hydrogen refrigerant carrier heat exchanger to provide a heat source for reheating the hydrogen, which is cooled and pressurized by the refrigerant carrier pump and then enters the refrigerant carrier cold energy storage heat exchanger to cool the room-temperature water coming from the circulating water system, wherein the room-temperature water, after being cooled to a low temperature, leaves the refrigerant carrier cold energy storage heat exchanger and enters the cold energy storage tank.where the low-temperature water from the cold energy storage tank can be sprayed through pipes and valves in the upper part of the water cooling tower to further lower the water temperature.

[0012] Preferably, the coolant carrier is an inorganic or organic compound, a mixture thereof, or an aqueous solution thereof. Preferably, the coolant carrier is an aqueous solution of an organic compound, such as an aqueous solution of ethylene glycol, an aqueous solution of propylene glycol, methanol, or an aqueous solution of ethanol.

[0013] Preferably, the water cooling tower is filled with a filler material.

[0014] The present invention has the following advantageous effects: In this invention, photovoltaic eco-electrolyte water is used for hydrogen production in conjunction with cryogenic technology for energy storage. When photovoltaic renewable energy is sufficient, the excess hydrogen produced by the eco-water electrolysis is liquefied with liquid nitrogen by the pre-cooled hydrogen liquefaction system and stored; when hydrogen production by the eco-water electrolysis is insufficient due to a decrease in photovoltaic renewable energy generation and environmental changes, the stored liquid hydrogen is evaporated and reheated by the liquid hydrogen-liquid nitrogen heat exchange system and cold energy storage system and then supplied to the downstream process piping network.Simultaneously, the liquid nitrogen obtained from the low-temperature heat exchange can serve as a partial pre-cooling source for the hydrogen liquefaction system; the cold energy stored in the cold energy storage system can be used by the cold energy utilization system of an air separation device. The invention solves the problem of the contradiction between the discontinuous production of eco-hydrogen from photovoltaic resources and the continuous demand for eco-hydrogen for production. The hydrogen storage method allows for the maximum utilization of renewable photovoltaic energy, and by implementing efficient energy storage and peak shaving, the energy consumption costs for the production and use of eco-hydrogen can be effectively reduced, resulting in energy savings and promising transport prospects. List of characters Fig. Figure 1 is a schematic representation of the present invention. Specific embodiments

[0015] To clarify the technical problems, solutions, and benefits that the present invention aims to solve, it will be described in more detail below in conjunction with the figures and specific embodiments. It should be noted that a person skilled in the art could make a number of improvements and modifications to the present invention without departing from its principles, and these improvements and modifications would fall within the scope of the claims of the present invention.

[0016] The invention is described in detail below in conjunction with the figures, as shown in the Fig.Figure 1 shows an energy storage device for hydrogen production by electrolytic water in conjunction with low temperature, the device comprising a pre-cooled liquid nitrogen hydrogen liquefaction system, a liquid hydrogen-liquid nitrogen heat exchange system, a cold energy storage system, and a cold energy utilization system of an air separation device, wherein the pre-cooled liquid nitrogen hydrogen liquefaction system comprises a liquid nitrogen inlet system 11, a nitrogen outlet system 12, a liquid hydrogen outlet system 13, and a hydrogen liquefaction system 14, each system being connected by piping and controlled by valves, and wherein the liquid hydrogen-liquid nitrogen heat exchange system comprises a liquid hydrogen storage tank 21, a liquid hydrogen pump 22, a liquid hydrogen-liquid nitrogen heat exchanger 23, and a liquid nitrogen storage tank 24.wherein each system is connected by piping and controlled by valves for the evaporation of liquid hydrogen and the liquefaction of nitrogen, wherein the liquid hydrogen inlet of the liquid hydrogen storage tank 21 is connected to the liquid hydrogen outlet system 13 of the pre-cooled hydrogen liquefaction system with liquid nitrogen, the liquid hydrogen inlet of the liquid hydrogen pump 22 is connected to the liquid hydrogen outlet of the liquid hydrogen storage tank 21, the liquid hydrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger 23 is connected to the liquid hydrogen outlet of the liquid hydrogen pump 22, the liquid nitrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger 23 is connected to the nitrogen outlet of the nitrogen outlet system 43 of the air separation unit of the cold energy utilization system,the liquid nitrogen outlet of the liquid hydrogen-liquid nitrogen heat exchanger 23 is connected to the liquid nitrogen inlet of the liquid nitrogen storage tank 24, the liquid nitrogen outlet of the liquid nitrogen storage tank 24 is connected to the inlet of the liquid nitrogen inlet system 11 of the pre-cooled hydrogen liquefaction system with liquid nitrogen, the cold energy storage system comprising a hydrogen-refrigerant carrier heat exchanger 31, a refrigerant carrier pump 32, a refrigerant carrier-cold energy storage heat exchanger 33, a refrigerant storage tank 34 and a cold energy storage tank 35, each system being connected by piping and controlled by valves for reheating hydrogen and storing cold energy,wherein the hydrogen inlet of the heat exchanger for hydrogen refrigerant carrier 31 is connected to the hydrogen outlet of the heat exchanger for liquid hydrogen / liquid nitrogen 23, the refrigerant carrier outlet of the heat exchanger for hydrogen refrigerant carrier 31 is connected to the refrigerant carrier inlet of the refrigerant carrier pump 32, the refrigerant carrier outlet of the refrigerant carrier pump 32 is connected to the refrigerant carrier inlet of the heat exchanger for refrigerant carrier / cold energy storage 33, the refrigerant carrier outlet of the heat exchanger for refrigerant carrier / cold energy storage 33 is connected to the refrigerant carrier inlet of the heat exchanger for hydrogen refrigerant carrier 31,wherein the water outlet of the heat exchanger for refrigerant carrier cold energy storage 33 is connected to the inlet of the cold energy storage tank 35 and the refrigerant storage tank 34 is connected to the refrigerant carrier inlet of the refrigerant carrier pump 32 by piping and valves, wherein the cold energy utilization system of an air separation device comprises a circulating water system 41, a water cooling tower 42, a nitrogen outlet system of the air separation system 43 and a chilled water inlet system of the air separation system 44, each system being interconnected by piping and controlled by valves, wherein the outlet of the circulating water system 41 is connected to the water inlet of the heat exchanger for refrigerant carrier cold energy storage 33, and the outlet of the cold energy storage tank 35 is connected to the upper inlet of the water cooling tower 42,the outlet of the nitrogen outlet system 12 is connected to the lower inlet of the water cooling tower 42 and the lower outlet of the water cooling tower 42 is connected to the inlet of the cold water inlet system of the air separation unit 44, wherein the liquid hydrogen-liquid nitrogen heat exchanger 23, the hydrogen-refrigerant carrier heat exchanger 31 and the refrigerant carrier-cold energy storage heat exchanger 33 are tube heat exchangers or plate heat exchangers, wherein the water cooling tower 42 is a packed tower.

[0017] An energy storage method for application to the energy storage device comprises the following steps; Step 1: if there is an excess of photoelectric eco-water electrolysis to hydrogen, the excess hydrogen can be liquefied by a hydrogen liquefaction system, wherein the liquid nitrogen is used as a pre-cooling source for the hydrogen liquefaction, wherein the liquefied liquid hydrogen is directed to a liquid hydrogen storage tank 21 for storage, the evaporated and room-temperature heated nitrogen from the nitrogen outlet system 12 is directed by piping to the lower part of the water cooling tower 42 and is sprayed through the low-temperature water in the upper part of the water cooling tower 42 from the cold energy storage tank 35, further cooling the low-temperature water, which is beneficial to the subsequent process of the air separation plant and reduces the energy consumption of the air separation plant.

[0018] Step 2: If the renewable energy power generation system, such as photovoltaics, is insufficient to produce hydrogen from eco-electrolyte water due to environmental changes, such as weakening sunlight, the liquid hydrogen stored in the liquid hydrogen storage tank 21 is pressurized by the liquid hydrogen pump 22 and then enters the liquid hydrogen / liquid nitrogen heat exchanger 23 to evaporate and reheat. It then enters the hydrogen / refrigerant carrier heat exchanger 31 to reheat and obtain room-temperature hydrogen, which is used to supplement the insufficient hydrogen production from eco-electrolyte water. The room-temperature nitrogen acts as a heat source for the evaporation and reheating of the liquid hydrogen from the nitrogen outlet system 43 into the liquid hydrogen / liquid nitrogen heat exchanger 23.which is liquefied and condensed to liquid nitrogen and then enters the liquid nitrogen storage tank 24 and can be used as a partial supplement for pre-cooling the liquid nitrogen during the liquefaction of the hydrogen, wherein the refrigerant carrier enters the hydrogen refrigerant carrier heat exchanger 31 to provide a heat source for reheating the hydrogen, which is cooled and pressurized by the refrigerant carrier pump 32 and then enters the refrigerant carrier cold energy storage heat exchanger 33 to cool the room temperature water coming from the circulating water system 41, wherein the room temperature water, after being cooled to a low temperature, leaves the refrigerant carrier cold energy storage heat exchanger 33 and enters the cold energy storage tank 35,the low-temperature water from the cold energy storage tank 35 can be sprayed through pipes and valves in the upper part of the water cooling tower 42 to further lower the water temperature.

[0019] The coolant carrier is an inorganic or organic compound, a mixture thereof, or an aqueous solution thereof. Preferably, the coolant carrier is an aqueous solution of an organic compound, such as an aqueous solution of ethylene glycol, an aqueous solution of propylene glycol, methanol, or an aqueous solution of ethanol, wherein the water cooling tower 42 is filled with a filler.

[0020] If there is an excess of hydrogen produced by the photoelectric eco-water electrolysis process, the excess hydrogen can be liquefied by a hydrogen liquefaction system 14. For the hydrogen liquefaction system 14, the liquid nitrogen pre-cooled hydrogen liquefaction system of the Claude hydrogen cycle or the Brayton helium cycle hydrogen liquefaction system is generally widely used on the market. The liquid nitrogen, as a pre-cooling source, is fed from the liquid nitrogen storage tank 24 into the hydrogen liquefaction system 14 via the inlet of the liquid nitrogen inlet system 11 after hydrogen liquefaction. The vaporized nitrogen from the nitrogen outlet system 12 is conveyed through piping to the lower part of the water cooling tower 42 and is sprayed through the low-temperature water in the upper part of the water cooling tower 42 from the cold energy storage tank 35.where the low-temperature water is further cooled. Reducing the low water temperature in the water cooling tower of the air separation system's pre-cooling system to a reasonable level, according to established knowledge of air separation systems, facilitates savings in the overall energy consumption of the air separation system and reduces the unit consumption of the air separation system's product.

[0021] If the renewable energy power generation system is insufficient to produce hydrogen from eco-electrolyte water due to environmental changes, such as weakening sunlight, the liquid hydrogen stored in the liquid hydrogen storage tank 21 is pressurized to, for example, 1.6 MPa by the liquid hydrogen pump 22 and then enters the liquid hydrogen-liquid nitrogen heat exchanger 23. Meanwhile, nitrogen at a temperature of approximately 25 °C from the nitrogen outlet system of the air separation unit 43 enters the liquid hydrogen-liquid nitrogen heat exchanger 23, which serves as a heat source for the evaporation and reheating of the liquid nitrogen. The liquid nitrogen is then liquefied and condensed into liquid nitrogen and then enters the liquid nitrogen storage tank 24, as well as being partially replenished at a refill rate of up to approximately...60% can be used for pre-cooling the liquid nitrogen during hydrogen liquefaction. The temperature of the evaporated and heated hydrogen from the liquid hydrogen-liquid nitrogen heat exchanger 23 is still very low, generally around -100°C. The hydrogen must be reheated in the hydrogen-refrigerant carrier heat exchanger 31 to obtain room-temperature hydrogen, which is used to supplement the shortfall in hydrogen production from eco-electrolyte water. The refrigerant carrier, e.g.,An aqueous solution of ethylene glycol enters the hydrogen refrigerant heat exchanger 31 to provide a heat source for reheating the hydrogen, which is cooled to approximately 0°C and then pressurized to approximately 0.1–0.3 MPa by the refrigerant pump 32. The hydrogen then enters the refrigerant cold energy storage heat exchanger 33 to cool the water at room temperature (30°C) from the circulating water system 41. The room temperature water is cooled to approximately 20°C to form low-temperature water. The low-temperature water exits the refrigerant cold energy storage heat exchanger 33 and is stored in the cold energy storage tank 35.The low-temperature water from the cold energy storage tank 35 can be continuously directed through pipes and valves into the upper part of the water cooling tower 42 for spraying, thereby further reducing the temperature of the low-temperature water to cold water.

Claims

[1] Energy storage device for hydrogen production by electrolytic water in conjunction with low temperature, characterized bythat the device comprises a pre-cooled liquid nitrogen hydrogen liquefaction system, a liquid hydrogen-liquid nitrogen heat exchange system, a cold energy storage system, and a cold energy utilization system of an air separation device, wherein the pre-cooled liquid nitrogen hydrogen liquefaction system comprises a liquid nitrogen inlet system, a nitrogen outlet system, a liquid hydrogen outlet system, and a hydrogen liquefaction system, each system being connected by piping and controlled by valves, and wherein the liquid hydrogen-liquid nitrogen heat exchange system comprises a liquid hydrogen storage tank, a liquid hydrogen pump, a liquid hydrogen-liquid nitrogen heat exchanger, and a liquid nitrogen storage tank, each system being connected by piping and controlled by valves for evaporating liquid hydrogen and liquefying nitrogen.wherein the liquid hydrogen inlet of the liquid hydrogen storage tank is connected to the liquid hydrogen outlet system of the pre-cooled hydrogen liquefaction system with liquid nitrogen, the liquid hydrogen inlet of the liquid hydrogen pump is connected to the liquid hydrogen outlet of the liquid hydrogen storage tank, the liquid hydrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the liquid hydrogen outlet of the liquid hydrogen pump, the liquid nitrogen inlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the nitrogen outlet of the nitrogen outlet system of the air separation unit of the cold energy utilization system, the liquid nitrogen outlet of the liquid hydrogen-liquid nitrogen heat exchanger is connected to the liquid nitrogen inlet of the liquid nitrogen storage tank,The liquid nitrogen outlet of the liquid nitrogen storage tank is connected to the inlet of the liquid nitrogen inlet system of the pre-cooled hydrogen liquefaction system with liquid nitrogen. [2] Energy storage device for hydrogen production by electrolytic water in conjunction with low temperature according to claim 1, characterized by, that the cold energy storage system comprises a hydrogen refrigerant heat exchanger, a refrigerant carrier pump, a refrigerant carrier cold energy storage heat exchanger, a refrigerant storage tank, and a cold energy storage tank, each system being connected by piping and controlled by valves for reheating hydrogen and storing cold energy, the hydrogen inlet of the hydrogen refrigerant heat exchanger being connected to the hydrogen outlet of the liquid hydrogen / liquid nitrogen heat exchanger, the refrigerant carrier outlet of the hydrogen refrigerant heat exchanger being connected to the refrigerant carrier inlet of the refrigerant carrier pump, and the refrigerant carrier outlet of the refrigerant carrier pump being connected to the refrigerant carrier inlet of the refrigerant carrier cold energy storage heat exchanger.The refrigerant carrier outlet of the heat exchanger for refrigerant carrier cold energy storage is connected to the refrigerant carrier inlet of the heat exchanger for hydrogen refrigerant carrier, the water outlet of the heat exchanger for refrigerant carrier cold energy storage is connected to the inlet of the cold energy storage tank, and the refrigerant storage tank is connected to the refrigerant carrier inlet of the refrigerant carrier pump by pipes and valves. [3] Energy storage device for hydrogen production by electrolytic water in conjunction with low temperature according to claim 2, characterized by, that the cold energy utilization system of an air separation device comprises a circulating water system, a water cooling tower, a nitrogen outlet system of the air separation system and a cold water inlet system of the air separation system, each system being interconnected by piping and controlled by valves, wherein the outlet of the circulating water system is connected to the water inlet of the heat exchanger for refrigerant carrier cold energy storage, the outlet of the cold energy storage tank is connected to the upper inlet of the water cooling tower, the outlet of the nitrogen outlet system is connected to the lower inlet of the water cooling tower and the lower outlet of the water cooling tower is connected to the inlet of the cold water inlet system of the air separation system. [4] Energy storage device for hydrogen production by electrolytic water in conjunction with low temperature according to claim 3, characterized bythat the heat exchanger for liquid hydrogen-liquid nitrogen, the heat exchanger for hydrogen-refrigerant carrier and the heat exchanger for refrigerant carrier-cold energy storage are tube heat exchangers or plate heat exchangers. [5] Energy storage device for hydrogen production by electrolytic water in conjunction with low temperature according to claim 3, characterized by that the water cooling tower is a packed-bed tower. [6] Energy storage method for application to the energy storage device according to any one of claims 1 to 5, characterized by, that step 1: if the photoelectric eco-water electrolysis to hydrogen is in excess, the excess hydrogen can be liquefied by a hydrogen liquefaction system, using liquid nitrogen as a pre-cooling source for the hydrogen liquefaction, the liquefied liquid hydrogen being directed to a liquid hydrogen storage tank for storage, the evaporated and room-temperature heated nitrogen from the nitrogen outlet system being directed through piping to the lower part of the water cooling tower and being sprayed through the low-temperature water in the upper part of the water cooling tower from the cold energy storage tank, further cooling the low-temperature water, which is beneficial to the subsequent air separation plant process and reduces the energy consumption of the air separation plant; and Step 2 includes: if the renewable energy power generation system is insufficient to produce hydrogen from eco-electrolyte water due to environmental changes, such as weakening sunlight, the liquid hydrogen stored in the liquid hydrogen storage tank is pressurized by the liquid hydrogen pump and then enters the liquid hydrogen-liquid nitrogen heat exchanger to evaporate and reheat, and then enters the hydrogen-refrigerant carrier heat exchanger to reheat and obtain room-temperature hydrogen, which is used to supplement the insufficient hydrogen production from eco-electrolyte water. The room-temperature nitrogen acts as a heat source for the evaporation and reheating of the liquid hydrogen from the nitrogen output system into the liquid hydrogen-liquid nitrogen heat exchanger.which is liquefied and condensed to liquid nitrogen and then enters the liquid nitrogen storage tank, and can also be used as a partial supplement to pre-cool the liquid nitrogen during the liquefaction of the hydrogen, wherein the refrigerant carrier enters the hydrogen refrigerant carrier heat exchanger to provide a heat source for reheating the hydrogen, which is cooled and pressurized by the refrigerant carrier pump and then enters the refrigerant carrier cold energy storage heat exchanger to cool the room-temperature water coming from the circulating water system, wherein the room-temperature water, after being cooled to a low temperature, leaves the refrigerant carrier cold energy storage heat exchanger and enters the cold energy storage tank.where the low-temperature water from the cold energy storage tank can be sprayed through pipes and valves in the upper part of the water cooling tower to further lower the water temperature. [7] Energy storage method according to claim 6, characterized by that the coolant carrier is an inorganic, organic compound or a mixture thereof, or an aqueous solution thereof. [8] Energy storage method according to claim 6, characterized by that the water cooling tower is filled with a filler material.

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