Hydrogen storage power generation system based on hydrogen carnot cell

Abstract

This invention discloses a hydrogen energy storage and power generation system based on a hydrogen Carnot battery. The system includes: a hydrogen production unit for producing hydrogen and oxygen through water electrolysis; a storage unit including a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank; a fuel cell power generation unit for generating electricity based on fuel hydrogen, producing a first electrical energy and high-temperature waste heat; a concentration cell power generation unit for generating electricity based on high-temperature waste heat and concentration-supplemented hydrogen, producing a second electrical energy; a cooling hydrogen circulation system for introducing cooling hydrogen that does not participate in the power generation reaction, flowing through the fuel cell power generation unit to remove high-temperature waste heat; and an expansion-compression coupling unit including a hydrogen expander, an oxygen expander, and a first compressor. This invention solves the technical problem of huge energy waste throughout the entire hydrogen energy storage and power generation system chain due to the complete waste of pressure potential energy during decompression in the high-pressure storage stage and the direct waste of waste heat in the fuel cell power generation stage.

Description

Technical Field

[0001] This invention relates to the field of hydrogen power generation technology, and more specifically, to a hydrogen energy storage and power generation system based on a hydrogen Carnot battery. Background Technology

[0002] With the large-scale grid integration of renewable energy, hydrogen energy storage has become an important vehicle for flexible grid regulation. However, current hydrogen power generation routes have significant drawbacks. The high-pressure hydrogen storage stage consumes a large proportion of energy during compression, and the pressure potential energy is completely wasted during decompression and release, resulting in an overall energy utilization rate of only 25%–30%, with over 70% of the electrical energy conversion suffering severe losses. Simultaneously, fuel cell operation generates a large amount of high-temperature waste heat, and traditional systems lack efficient recovery mechanisms, leading to the direct emission of high-quality heat energy and secondary waste. Furthermore, the hydrogen production process consumes a large amount of water, limiting its application in areas rich in wind and solar power but lacking in water resources; long-distance hydrogen storage and transportation are costly and have low safety, further restricting the economic viability and large-scale consumption of green hydrogen.

[0003] In particular, new energy power generation, represented by wind and solar power, is intermittent and volatile—peak power generation does not match peak electricity consumption, and hydrogen production and power generation are decoupled in time. This characteristic places comprehensive demands on energy storage systems, including power and capacity decoupling, long-term storage, and rapid response. However, current technologies have failed to achieve system-level thermodynamic coupling of mechanical recovery of pressure potential energy, waste heat-driven concentration cell power generation, and water vapor condensation cycle, making it difficult to achieve synergistic optimization of energy and matter, and even more difficult to effectively cope with the complex operating conditions brought about by the volatility of new energy sources.

[0004] There is currently no effective solution to the above problems, and this invention is proposed to solve these problems. Summary of the Invention

[0005] This invention provides a hydrogen energy storage and power generation system based on a hydrogen Carnot battery, which at least solves the technical problem that the pressure potential energy in the high-pressure storage stage is completely wasted during the decompression process and the waste heat in the fuel cell power generation stage is directly discarded, resulting in huge energy waste in the entire chain of hydrogen energy storage and power generation systems.

[0006] According to one aspect of the present invention, a hydrogen energy storage and power generation system based on a hydrogen Carnot battery is provided, comprising: a hydrogen production unit for producing hydrogen and oxygen by electrolysis of water; a storage unit including a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank, wherein the high-pressure hydrogen tank is used to store hydrogen, the high-pressure oxygen tank is used to store oxygen, and the low-pressure hydrogen tank is used to receive and expand hydrogen introduced from the high-pressure hydrogen tank; a fuel cell power generation unit for generating electricity based on fuel hydrogen, producing a first electrical energy and high-temperature waste heat, wherein the fuel hydrogen is obtained by compressing cooled hydrogen; a concentration cell power generation unit including a plurality of concentration cells, each with its own anode chamber and cathode chamber, the cathode chamber containing a mixture of hydrogen and an inert gas, the partial pressure of hydrogen being reduced by dilution with the inert gas, the concentration cell power generation unit being used to generate electricity based on the high-temperature waste heat and concentration-supplemented hydrogen, producing a second electrical energy; and a cooling hydrogen circulation for introducing cooling hydrogen that does not participate in the power generation reaction, flowing through the fuel cell power generation unit to remove the high-temperature waste heat, the flow rate of the cooling hydrogen being 5 to 12 times the flow rate of hydrogen consumed by the reaction in the fuel cell power generation unit; and an expansion... The expansion-compression coupling unit includes a hydrogen expander, an oxygen expander, and a first compressor. The hydrogen expander and oxygen expander are coaxially coupled. The hydrogen expander recovers the first pressure potential energy by utilizing the pressure drop generated during the release of hydrogen from the high-pressure hydrogen tank to the low-pressure hydrogen tank. The oxygen expander recovers the second pressure potential energy by utilizing the pressure drop generated during the release of oxygen from the high-pressure oxygen tank to the atmosphere. The first and second pressure potential energies together drive the first compressor to compress the hydrogen in the cooling hydrogen circulation into concentration-supplemented hydrogen. The high-temperature waste heat generated by the fuel cell power generation unit serves as the constant-temperature heat source for the concentration cell power generation unit, forming a small Carnot cycle. The hydrogen production unit, storage unit, and fuel cell power generation unit form a large Carnot cycle. The large Carnot cycle and the small Carnot cycle are coupled in terms of matter and energy. That is, the large Carnot cycle and the small Carnot cycle achieve material flow coupling through the equal flow constraints of the fuel hydrogen bypass and the cooling hydrogen bypass. The water vapor generated by the fuel cell power generation unit is condensed and then returned to the hydrogen production unit to form a material closed loop of reversible water resource circulation, constituting a closed loop of conversion from electrical energy to chemical energy and from chemical energy to electrical energy.

[0007] Optionally, the system further includes an electrical connection unit for inverting the first and second electrical energy into alternating current and inputting it into the target power grid.

[0008] Optionally, the hydrogen production unit further includes a second compressor for compressing the hydrogen obtained from electrolysis and transferring it to a high-pressure hydrogen tank for storage.

[0009] Optionally, the system further includes: a hydrogen bypass for starting up when the hydrogen energy storage and power generation system based on a hydrogen Carnot battery is started up, generating a cooling hydrogen circulation, and shutting down after startup is complete.

[0010] Optionally, the system further includes: a fuel hydrogen bypass for feeding fuel hydrogen into the fuel cell power generation unit; and a cooling hydrogen bypass for supplementing the cooling hydrogen circulation with hydrogen; the flow rate of the fuel hydrogen bypass is equal to the flow rate of the cooling hydrogen bypass.

[0011] Optionally, the fuel cell power generation unit further includes: a fuel cell for electrochemical reaction based on fuel hydrogen to generate water vapor; a first waste heat recovery module for condensing the water vapor into condensate; a second waste heat recovery module for exchanging heat between the condensate and hydrogen in the cooling hydrogen circulation to raise the temperature of the hydrogen in the cooling hydrogen circulation for input into the concentration cell power generation unit for power generation; and an excess hydrogen circulation pipeline for returning hydrogen discharged from the anode outlet of the fuel cell to the anode inlet of the fuel cell.

[0012] Optionally, the fuel cell power generation unit also includes a water collection tank for collecting condensate and replenishing it to a water tank used in the water electrolysis process, forming a reversible water resource cycle.

[0013] Optionally, the concentration cell operates at a temperature of 170°C to 700°C, the high-pressure hydrogen chamber of the concentration cell has a pressure of 4MPa to 6MPa, the hydrogen partial pressure of the low-pressure hydrogen chamber of the concentration cell is 0.1MPa to 0.5MPa, the total pressure of the low-pressure hydrogen chamber is equal to the pressure of the high-pressure hydrogen chamber and is maintained by nitrogen, the concentration supplement hydrogen is evenly and synchronously distributed to multiple concentration cells to form a parallel gas path network, and the output terminals of multiple concentration cells are connected end to end in sequence to form a series circuit network.

[0014] Optionally, the low-pressure hydrogen chamber serves as the cathode chamber of the concentration cell, and the high-pressure hydrogen chamber serves as the anode chamber of the concentration cell. The partial pressure of hydrogen in the cathode chamber is lower than the hydrogen pressure in the anode chamber. The mixed gas in the cathode chamber includes hydrogen and nitrogen, and the partial pressure of nitrogen is the difference between the total pressure of the cathode chamber and the partial pressure of hydrogen.

[0015] Optionally, the concentration cell further includes: a desorption module for separating hydrogen and nitrogen in the mixed gas discharged from the low-pressure hydrogen chamber outlet of the concentration cell using hydrogen storage alloy powder to obtain pure hydrogen; and a cooling module for cooling the pure hydrogen when the temperature of the pure hydrogen is higher than a preset temperature threshold.

[0016] Optionally, the low-pressure hydrogen tank is also equipped with an external delivery interface. When the external system of the hydrogen energy storage and power generation system based on the hydrogen Carnot battery has a demand for hydrogen and the hydrogen content in the low-pressure hydrogen tank reaches a preset content threshold, the external delivery interface is opened to replenish hydrogen to the external system.

[0017] Optionally, the pressure range of the high-pressure hydrogen tank is 20 MPa to 90 MPa, the pressure range of the high-pressure oxygen tank is 1.5 MPa to 6 MPa, and the pressure range of the low-pressure hydrogen tank is 5 MPa to 20 MPa.

[0018] In this embodiment of the invention, a hydrogen energy storage and power generation system based on a hydrogen Carnot battery is employed. A hydrogen production unit is used to produce hydrogen and oxygen through water electrolysis. A storage unit includes a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank. The high-pressure hydrogen tank stores hydrogen, the high-pressure oxygen tank stores oxygen, and the low-pressure hydrogen tank receives and expands the hydrogen from the high-pressure hydrogen tank. A fuel cell power generation unit generates electricity based on fuel hydrogen, producing first-stage electrical energy and high-temperature waste heat. The fuel hydrogen is obtained by compressing cooled hydrogen. A concentration cell power generation unit includes multiple concentration cells, each with its own anode chamber and cathode chamber. The cathode chamber contains a mixture of hydrogen and inert gas. The inert gas dilutes the hydrogen to reduce its partial pressure. The concentration cell power generation unit generates electricity based on the high-temperature waste heat and concentration-supplemented hydrogen, producing a second source of electrical energy. A cooling hydrogen circulation system introduces cooling hydrogen that does not participate in the power generation reaction. This cooling hydrogen flows through the fuel cell power generation unit, carrying away the high-temperature waste heat. The flow rate of the cooling hydrogen is 5 to 12 times the flow rate of hydrogen consumed in the fuel cell power generation unit reaction. An expansion-compression coupling unit includes a hydrogen expander, an oxygen expander, and a first compressor. The hydrogen expander and oxygen expander are coaxially coupled. The machine recovers the first pressure potential energy by utilizing the pressure drop generated during the release of hydrogen from the high-pressure hydrogen tank to the low-pressure hydrogen tank, and the oxygen expander recovers the second pressure potential energy by utilizing the pressure drop generated during the release of oxygen from the high-pressure oxygen tank to the atmosphere. The first and second pressure potential energies together drive the first compressor to compress the hydrogen in the cooling hydrogen circulation into concentration-filled hydrogen. The high-temperature waste heat generated by the fuel cell power generation unit serves as a constant-temperature heat source for the concentration cell power generation unit, forming a small Carnot cycle. The hydrogen production unit, storage unit, and fuel cell power generation unit form a large Carnot cycle. The large Carnot cycle and the small Carnot cycle are related in terms of physical properties. By coupling matter and energy, a closed loop of conversion from electrical energy to chemical energy and from chemical energy to electrical energy is formed, achieving the goal of recovering pressure potential energy and converting the high-temperature waste heat of fuel cells into electrical energy in a cascade manner. This realizes the technical effect of coupling the large Carnot cycle and the small Carnot cycle and improving the energy utilization rate of the entire chain. In turn, it solves the technical problem that the pressure potential energy in the high-pressure storage stage is completely wasted during the decompression process and the waste heat in the fuel cell power generation stage is directly discarded, resulting in huge energy waste in the entire chain of hydrogen energy storage and power generation systems. The efficiency of converting electrical energy into hydrogen energy and then hydrogen energy back into electrical energy in the entire chain can be improved to 55%~65%. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0020] Figure 1 This is a schematic diagram of a hydrogen energy storage and power generation system based on a hydrogen Carnot battery according to an optional embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a large Carnot cycle principle provided by an optional embodiment of the present invention;

[0022] Figure 3 This is a schematic diagram of a small Carnot cycle principle provided by an optional embodiment of the present invention;

[0023] Figure 4 This is a schematic diagram of an electro-hydrogen-electric coupling energy storage and power generation system based on the coupling of a large Carnot cycle and a small Carnot cycle, according to an optional embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of an electrical connection provided according to an optional embodiment of the present invention;

[0025] Figure 6 This is a schematic diagram of a fuel cell waste heat recovery method according to an optional embodiment of the present invention;

[0026] Figure 7 This is a schematic diagram of the structure of a concentration cell power generation unit provided by an optional embodiment of the present invention;

[0027] Figure 8 This is a schematic diagram of the internal structure of a single concentration cell according to an optional embodiment of the present invention;

[0028] Figure 9 This is a schematic diagram of a 60kW-class hydrogen energy storage and power generation system based on a hydrogen Carnot battery, according to an optional embodiment of the present invention. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0031] According to embodiments of the present invention, a hydrogen energy storage and power generation system based on a hydrogen Carnot battery is provided. Figure 1 This is a schematic diagram of a hydrogen energy storage and power generation system based on a hydrogen Carnot battery, according to an optional embodiment of the present invention. Figure 1 As shown, the system includes the following structure:

[0032] The hydrogen production unit is used to produce hydrogen and oxygen by electrolyzing water.

[0033] Optionally, the core function of the hydrogen production unit is to utilize electricity generated from renewable energy sources to decompose water molecules into hydrogen and oxygen through water electrolysis, thus converting electrical energy into a chemical energy carrier and completing the initial storage of "electricity-hydrogen" energy. This unit is not only the source of hydrogen production but also the starting point of the large Carnot cycle. Specifically, the electrolysis process consumes electricity from the grid or renewable energy sources to produce high-pressure hydrogen and oxygen. Oxygen is typically stored directly in a high-pressure oxygen tank during the electrolysis process, requiring no additional compression energy consumption; while hydrogen needs to be pressurized to a high-pressure state by a second compressor and stored in a high-pressure hydrogen tank to utilize its enormous pressure potential energy. This process not only achieves hydrogen production and high-pressure storage but also lays the material and energy foundation for subsequent fuel cell power generation and pressure potential energy recovery.

[0034] The storage unit includes a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank, wherein the high-pressure hydrogen tank is used to store hydrogen, the high-pressure oxygen tank is used to store oxygen, and the low-pressure hydrogen tank is used to receive and expand the hydrogen introduced from the high-pressure hydrogen tank.

[0035] Optionally, the storage unit consists of a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank, designed to achieve efficient hydrogen storage, pressure potential energy recovery, and system coupling through multi-pressure level synergy. The high-pressure hydrogen tank temporarily stores hydrogen produced by the electrolysis hydrogen production unit, with a pressure range of 20 MPa to 90 MPa. This wide-range design balances energy storage density and equipment safety under different operating conditions, ensuring a continuous and stable supply of high-pressure hydrogen. The high-pressure oxygen tank stores oxygen, a byproduct of electrolysis, with a pressure range of 1.5 MPa to 6 MPa. Its pressure is matched to the hydrogen storage pressure, facilitating subsequent recovery of pressure potential energy via an oxygen expander to support system operation. The low-pressure hydrogen tank not only serves as a buffer container but, more importantly, receives hydrogen from the high-pressure hydrogen tank via the expansion-compression coupling unit. The expansion of hydrogen from high pressure to low pressure drives the hydrogen expander to recover the first pressure potential energy. This potential energy is then converted into mechanical energy, driving the first compressor to compress the hydrogen in the cooling hydrogen circulation into supplementary hydrogen required for the concentration cell, thus achieving cascade utilization of pressure potential energy. The low-pressure hydrogen tank is set to a pressure range of 5 MPa to 20 MPa, which ensures an appropriate pressure drop during the expansion process to maximize energy recovery efficiency, while avoiding the problem of excessively large equipment size due to excessively low pressure. At the same time, it provides a flexible external interface for the system, which can adjust the output according to external needs and optimize the overall energy balance.

[0036] The fuel cell power generation unit is used to generate electricity based on fuel hydrogen, producing first electrical energy and high-temperature waste heat, wherein the fuel hydrogen is obtained by compressing cooled hydrogen.

[0037] Optionally, hydrogen in the high-pressure hydrogen tank (20-90 MPa) is expanded to a low-pressure hydrogen tank (5-20 MPa) by a hydrogen expander. The released pressure potential energy (first pressure potential energy) and the second pressure potential energy released by the expansion of oxygen in the high-pressure oxygen tank jointly drive a coaxially coupled first compressor. This compressor uses the recovered pressure energy to compress the hydrogen in the cooling hydrogen circulation, thereby obtaining cooled hydrogen with sufficient pressure. This compressed cooled hydrogen is then input as "fuel hydrogen" into the fuel cell power generation unit. In this process, the pressure difference between the high-pressure and low-pressure hydrogen tanks is converted into mechanical work to drive the compression process, ensuring that the cooled hydrogen entering the fuel cell has suitable reaction conditions. This achieves zero-cost recovery of the pressure potential energy of the high-pressure hydrogen storage tank and avoids the energy consumption of traditional compression.

[0038] Specifically, the above process can correspond to a generalized large Carnot cycle. Figure 2 This is a schematic diagram of a large Carnot cycle principle provided by an optional embodiment of the present invention, such as... Figure 2As shown, the absorption and release of electrical work (non-volume work) replaces the isothermal heat absorption and release of the traditional Carnot cycle, forming a complete energy and matter double closed loop: Process ab (isothermal reversible expansion 2H2O→2H2+O2): The electrolytic cell electrolyzes room temperature H2O, liquid water is converted into gaseous hydrogen and oxygen, volume expansion occurs, and renewable energy electrical work Φ1 is absorbed under a constant electric field, the system stores energy; Process bc (adiabatic reversible expansion): High-pressure, low-temperature H2 and O2 undergo adiabatic expansion through an energy recovery matching system, pressure... The volumetric work consumed by the system is reduced and converted into recoverable mechanical energy; process cd (isothermal reversible compression 2H2 + O2 → 2H2O): low-pressure, low-temperature H2 enters the high-temperature proton membrane fuel cell to generate electricity, gaseous hydrogen and oxygen react to generate liquid water, volume compression, and non-volume work Φ2 is done on the power grid under a constant electric field, releasing electrical energy. At the same time, the water vapor generated by the reaction releases latent heat into the environment through condensation; process da (adiabatic reversible compression): H2O is adiabatically compressed by a water pump through the water replenishment system and sent back to the electrolyzer, completing the material cycle.

[0039] The concentration cell power generation unit includes multiple concentration cells, each with its own anode chamber and cathode chamber. The cathode chamber contains a mixture of hydrogen and inert gas. The partial pressure of hydrogen is reduced by diluting the hydrogen with inert gas. The concentration cell power generation unit is used to generate electricity based on the high-temperature waste heat and the concentration-supplemented hydrogen to produce a second electrical energy.

[0040] Optionally, the concentration cell power generation unit uses the high-temperature waste heat generated by the fuel cell as a heat source and compressed concentration-addition hydrogen as the working fluid to convert thermal energy into electrical energy. The cooling hydrogen circulation absorbs waste heat from the fuel cell and is then heated, serving as a high-temperature heat source input to the high-pressure hydrogen chamber of the concentration cell. Simultaneously, the hydrogen compressor utilizes the pressure potential energy recovered from hydrogen expansion to compress the cooled hydrogen into high-pressure concentration-addition hydrogen, which is then sent to the high-pressure chamber, forming a concentration potential with the low hydrogen partial pressure environment of the low-pressure chamber. Through a high-temperature proton exchange membrane, the hydrogen spontaneously diffuses, performing work to generate electricity, thus producing a second form of electrical energy.

[0041] This process corresponds to the small Carnot cycle. Figure 3 This is a schematic diagram of a small Carnot cycle principle provided by an optional embodiment of the present invention, such as... Figure 3As shown, pressure energy and thermal energy are converted in stages, forming a heat engine cycle together with the concentration cell power generation unit: Process 1-2 (Isothermal Reversible Expansion): The hydrogen in the cooling circulation absorbs the waste heat of the fuel cell and outputs electrical power through reversible expansion of the concentration cell at an isothermal temperature of 500-650℃; Process 2-3 (Adiabatic Reversible Expansion): The hydrogen in the nitrogen-hydrogen mixture in the cathode chamber is released after selective absorption by the hydrogen storage alloy powder, and the pressure drops from the total cathode pressure to the alloy powder outlet pressure (0.15-0.4MPa), and the temperature drops significantly to near the ambient temperature; Process 3-4 (Isothermal Reversible Heat Release): When the hydrogen temperature at the outlet of the hydrogen storage alloy powder is higher than the ambient temperature, the low-temperature hydrogen cooling system is activated for isothermal cooling, releasing heat to the environment (25℃ isothermal cold source); Process 4-1 (Adiabatic Reversible Compression): The compressor driven by the expander adiabatically compresses the low-temperature, low-pressure hydrogen to a high pressure (4-6MPa).

[0042] Furthermore, in concentration cells, the electrical output depends on the chemical potential difference of hydrogen between the anode (high-pressure oxygen chamber) and the cathode (low-pressure hydrogen chamber), i.e., the hydrogen partial pressure difference. To achieve this, the cathode chamber is not directly supplied with low-pressure pure hydrogen, but rather a mixture of hydrogen and an inert gas (such as nitrogen). According to Dalton's law of partial pressures, the total pressure of the mixture is equal to the sum of the partial pressures of each component gas. By precisely controlling the injection amount of inert gas, the mole fraction of hydrogen in the mixture can be significantly reduced while maintaining the balance between the total pressure in the cathode chamber and the anode chamber (to avoid uneven stress on the membrane module), thereby effectively reducing the partial pressure of hydrogen. This dilution effect results in a hydrogen partial pressure on the cathode side being much lower than the high pressure on the anode side, forming a stable hydrogen concentration gradient that drives hydrogen ions to migrate from the anode to the cathode through the proton exchange membrane, generating an electric current. Simultaneously, the inert gas, acting as a carrier, does not participate in the electrochemical reaction, thus providing isolation and protection.

[0043] The cooling hydrogen circulation is used to introduce cooling hydrogen that does not participate in the power generation reaction. It flows through the fuel cell power generation unit to remove the high-temperature waste heat. The flow rate of the cooling hydrogen is 5 to 12 times the flow rate of hydrogen consumed by the reaction in the fuel cell power generation unit.

[0044] Optionally, hydrogen gas, which does not participate in the electrochemical reaction, is introduced into the circulating flow as a cooling medium, flowing through the interior of the fuel cell unit to remove the high-temperature waste heat generated by the electrochemical reaction. The flow rate of the cooling hydrogen is strictly controlled between 5 and 12 times the hydrogen flow rate consumed by the fuel cell reaction. This specific flow rate ratio design is based on the principle of heat balance: on the one hand, sufficient excess hydrogen ensures that a large amount of reaction heat can be fully absorbed and carried away, providing a sufficient and stable high-temperature heat source for subsequent concentration cell power generation; on the other hand, this flow rate range takes into account the economics of system pressure drop and pumping power consumption. During operation, the temperature of the cooled hydrogen gas increases significantly after absorbing heat, and then it transfers heat to the concentration cell or is used for preheating, cools itself down, and is then compressed and returned to the circulating flow. This design not only realizes the cascade transfer of waste heat from the fuel cell to the concentration cell, forming the heat source part of the small Carnot cycle, but also achieves precise matching of material flow and energy flow through flow control, significantly improving the overall energy utilization rate.

[0045] The expansion-compression coupling unit includes a hydrogen expander, an oxygen expander, and a first compressor. The hydrogen expander and the oxygen expander are coaxially coupled. The hydrogen expander recovers the first pressure potential energy by utilizing the pressure drop generated during the release of hydrogen from the high-pressure hydrogen tank to the low-pressure hydrogen tank. The oxygen expander recovers the second pressure potential energy by utilizing the pressure drop generated during the release of oxygen from the high-pressure oxygen tank to the atmosphere. The first and second pressure potential energies together drive the first compressor to compress the hydrogen in the cooling hydrogen circulation into concentration-supplemented hydrogen.

[0046] Optionally, the unit consists of a coaxially coupled hydrogen expander, an oxygen expander, and a first compressor. A high-pressure hydrogen tank (20-90 MPa) releases hydrogen to a low-pressure hydrogen tank (5-20 MPa), and the hydrogen expander utilizes this significant pressure drop to recover the first pressure potential energy. Simultaneously, a high-pressure oxygen tank (1.5-6 MPa) releases oxygen to the atmosphere, and the oxygen expander utilizes this pressure difference to recover the second pressure potential energy. The mechanical energy generated by both directly drives the coaxial first compressor, compressing the hydrogen flowing through the preheated and cooled hydrogen circulation of the fuel cell to form concentration supplement hydrogen for concentration cell power generation. This design converts the high-pressure gas expansion energy wasted in traditional energy storage into the high-pressure working fluid compression work required to drive the concentration cell, avoiding additional power consumption and ensuring the pressure conditions required for the high-pressure hydrogen chamber of the concentration cell. Through the dual-path potential energy coupling drive of hydrogen and oxygen, the system achieves closed-loop energy matching from high-pressure storage to energy recovery and secondary power generation, significantly reducing auxiliary machine energy consumption and supporting the efficient coordinated operation of the large and small Carnot cycles.

[0047] The large Carnot cycle and the small Carnot cycle are coupled: the high-temperature waste heat generated by the fuel cell power generation unit serves as the constant-temperature heat source for the concentration cell power generation unit, forming the small Carnot cycle. The hydrogen production unit, storage unit, and fuel cell power generation unit form the large Carnot cycle. The large Carnot cycle and the small Carnot cycle are coupled in terms of matter and energy, forming a closed loop of conversion from electrical energy to chemical energy and from chemical energy to electrical energy.

[0048] Optionally, the large Carnot cycle is driven by electrical work. The hydrogen production unit uses renewable energy to electrolyze water to generate hydrogen chemical energy, and the high-pressure hydrogen tank and high-pressure oxygen tank in the storage unit use pressure potential energy to store energy. The fuel cell power generation unit converts the chemical energy of hydrogen into the first electrical energy, while generating high-temperature waste heat and producing water vapor, completing the conversion of chemical energy into electrical energy. The small Carnot cycle is driven by the high-temperature waste heat of the fuel cell. This waste heat serves as a constant-temperature heat source to supply the concentration cell power generation unit. The concentration-added hydrogen undergoes reversible expansion in the concentration cell to generate the second electrical energy, realizing the recovery of heat energy into electrical energy. The two cycles are closely coupled in terms of matter and energy: the water vapor generated by the fuel cell in the large Carnot cycle releases latent heat through condensation, providing a heat source for the small Carnot cycle; the recovered pressure potential energy drives the compressor through the expansion-compression coupling unit to provide the concentration-added hydrogen required by the concentration cell; the cooling hydrogen circulation carries away waste heat in the fuel cell and preheats it before entering the concentration cell, realizing the cascade utilization of heat. This coupling mechanism not only recovers the pressure potential energy of the high-pressure storage tank and the waste heat of the fuel cell, but also realizes the recycling of water, constructing a highly efficient closed loop of "electrical work-chemical energy-electrical work", which significantly improves the energy utilization rate of the entire chain.

[0049] Specifically, the large Carnot cycle and the small Carnot cycle can be precisely coupled through the following steps: Energy coupling: The latent heat of condensation released in the large Carnot process cd serves as the heat source for the small Carnot process 1-2 (isothermal reversible expansion), and the exothermic process of the large Carnot provides an isothermal heat source for the small Carnot; Material coupling: The liquid water generated in the large Carnot process cd is pressurized back to the electrolyzer through process da, completing the water cycle; Pressure energy coupling: The pressure energy recovered in the large Carnot process bc is used to drive the compressor in the small Carnot process 4-1; Flow coupling: The flow rates of the fuel hydrogen bypass and the cooling hydrogen bypass are equal, achieving precise material matching between the two cycles. The large Carnot process cd includes two sub-processes: sub-process c-d1 is the reaction of hydrogen and oxygen in the fuel cell to generate high-temperature water vapor and release electrical work Φ2; sub-process c-d2 is the isothermal reversible exothermic phase transformation of the high-temperature water vapor into liquid water through a condenser. The isothermal reversible heat release of subprocess c-d2 is the heat source required for small Carnot cycle processes 1-2. The two are perfectly coupled in terms of changes in the state of matter (gas → liquid) and energy transfer (latent heat release → absorption).

[0050] Therefore, by combining the large Carnot cycle and the small Carnot cycle, the above-mentioned hydrogen power generation system can be further refined. Figure 4This is a schematic diagram of an electro-hydrogen-electric coupling energy storage and power generation system based on the coupling of a large Carnot cycle and a small Carnot cycle, according to an optional embodiment of the present invention. Figure 4 As shown, the system includes: an electrolysis hydrogen production unit for producing hydrogen and oxygen by electrolyzing water using renewable energy; a hydrogen storage unit and an oxygen storage unit for storing the hydrogen and oxygen produced by electrolysis; the hydrogen storage unit includes a high-pressure hydrogen tank and a low-pressure hydrogen tank, with the high-pressure tank having a pressure range of 30-50 MPa and the low-pressure hydrogen tank having a pressure range of 10-20 MPa, the low-pressure hydrogen tank also serving as an interface for hydrogen consumption and external transmission; the oxygen storage unit includes a high-pressure oxygen tank with a pressure range of 2-4 MPa; and a fuel cell power generation unit for converting the chemical energy of hydrogen into electrical energy and producing… The system includes: a high-temperature waste heat recovery unit; a concentration cell power generation unit for recovering high-temperature waste heat from the fuel cell and generating electricity through a hydrogen concentration cell; an expansion-compression coupling unit, including a hydrogen expansion-compression coupling device and an oxygen expansion-compression coupling device, for recovering the pressure potential energy of the high-pressure hydrogen / oxygen storage tank and driving the system cycle; a cooling and water recovery unit for recovering water vapor from the fuel cell exhaust gas and realizing water resource recycling; and an electrical connection unit for inverting the electrical energy output from the fuel cell and concentration cell and connecting it to the power grid, and for powering the system auxiliary equipment.

[0051] Through the above structure, the purpose of recovering pressure potential energy and converting the high-temperature waste heat of fuel cells into electrical energy in a cascade manner is achieved. This realizes the technical effect of coupling the large Carnot cycle and the small Carnot cycle and improving the energy utilization rate of the whole chain. In turn, it solves the technical problem that the pressure potential energy in the high-pressure storage stage is completely wasted during the decompression process and the waste heat in the fuel cell power generation stage is directly discarded, resulting in huge energy waste in the entire chain of hydrogen energy storage and power generation systems. The efficiency of converting electrical energy into hydrogen energy and then hydrogen energy back into electrical energy can be improved to 55%~65%.

[0052] As an optional embodiment, the system further includes an electrical connection unit for inverting the first electrical energy and the second electrical energy into alternating current and inputting them into the target power grid.

[0053] Optionally, the electrical connection unit includes a first inverter and a second inverter, corresponding to the first electrical energy generated by the fuel cell power generation unit and the second electrical energy generated by the concentration cell power generation unit, respectively. Figure 5 This is an electrical connection diagram provided by an optional embodiment of the present invention, such as... Figure 5As shown, the first inverter is connected to the fuel cell output, converting DC power to AC power for grid connection; the second inverter is connected to the concentration cell output, converting DC power to AC power for grid connection; the hydrogen circulation pump inverter, air compressor inverter, and electrolyzer makeup water pump inverter are connected to their respective auxiliary equipment, powered by the system's own power generation or the grid. Since both the fuel cell and concentration cell output DC power, while the target grid accepts AC power, the inverters convert the DC power to AC power that conforms to the grid's frequency and voltage standards. This design achieves grid connection of dual power sources: the first is the main power source directly generated by the fuel cell, and the second is a secondary power source based on waste heat recovery. Through inverter grid connection, the system integrates the two parts of electrical energy generated during the "electricity-hydrogen-electricity" conversion process into the target grid, not only achieving standardized output of electrical energy but also improving the continuity and stability of power supply through dual-source complementarity.

[0054] As an optional embodiment, the hydrogen production unit further includes a second compressor for compressing the hydrogen obtained from electrolysis and transferring it to a high-pressure hydrogen tank for storage.

[0055] Optionally, a second compressor is positioned after the electrolyzer and before the high-pressure hydrogen tank. Its function is to compress the low-pressure hydrogen produced by water electrolysis to the pressure required for high-pressure hydrogen storage. This process not only achieves high-density hydrogen storage, providing sufficient pressure potential energy reserves for the subsequent adiabatic expansion work in the large Carnot cycle, but also ensures that the working fluid parameters entering the high-pressure hydrogen tank match the overall thermodynamic model of the system. By precisely controlling the compression endpoint pressure, the second compressor ensures a sufficient pressure difference between the high-pressure and low-pressure hydrogen tanks, thereby driving the hydrogen expander to efficiently recover the initial pressure potential energy.

[0056] As an optional embodiment, the system further includes: an activation hydrogen bypass, which is used to activate during startup of the hydrogen energy storage and power generation system based on a hydrogen Carnot battery, generate a cooling hydrogen circulation, and shut down after startup is completed.

[0057] Optionally, during initial system startup or when the cooling hydrogen circulation is insufficient, the hydrogen bypass is activated. High-pressure hydrogen from the high-pressure hydrogen tank is depressurized through throttling expansion and then injected into the cooling hydrogen circulation. This rapidly establishes the working pressure of the cooling hydrogen circulation and the high-pressure hydrogen chamber of the concentration cell, maintaining the high-pressure hydrogen chamber pressure at 4-6 MPa. After startup, the bypass is closed. During operation, the high-pressure hydrogen chamber pressure is controlled collaboratively by the expansion-compression coupling system, ensuring that the fuel cell stack receives sufficient cooling hydrogen flow to maintain thermal balance during heating and the initial stage of operation. This design avoids the drawbacks of traditional startup methods that rely on external gas sources or complex pretreatment processes. This bypass provides a fundamental source for the flow balance control of subsequent cooling hydrogen and fuel hydrogen bypasses, ensuring precise coupling of the large and small Carnot cycles in terms of mass flow.

[0058] As an optional embodiment, the system further includes: a fuel hydrogen bypass for inputting fuel hydrogen into the fuel cell power generation unit; and a cooling hydrogen bypass for supplementing the cooling hydrogen circulation with hydrogen; the flow rate of the fuel hydrogen bypass is equal to the flow rate of the cooling hydrogen bypass.

[0059] Optionally, the fuel hydrogen bypass replenishes the hydrogen consumed by the electrochemical reaction at the fuel cell anode to maintain continuous power generation; the cooling hydrogen bypass replenishes the hydrogen lost due to leakage or balance losses in the cooling hydrogen loop to ensure continuous thermal management cycle. Both have equal flow rates. This design is based on the principle of overall system mass conservation: under steady-state operation, the amount of hydrogen consumed by the fuel cell equals the amount of hydrogen needed to replenish the cooling loop. Through this coordinated control with equal flow rates, the system not only avoids frequent intervention from external hydrogen sources, reducing control complexity, but also achieves perfect offsetting of reaction consumption and cycle losses in terms of mass. This means that the supplementary hydrogen drawn from the high-pressure hydrogen tank meets power generation requirements while maintaining the mass balance of the heat carrier loop, thus ensuring a stable supply to the high-pressure side of the concentration cell.

[0060] As an optional embodiment, the fuel cell power generation unit further includes: a fuel cell for performing an electrochemical reaction based on fuel hydrogen to generate water vapor; a first waste heat recovery module for condensing the water vapor into condensate; a second waste heat recovery module for exchanging heat between the condensate and hydrogen in the cooling hydrogen circulation to raise the temperature of the hydrogen in the cooling hydrogen circulation for use in the concentration cell power generation unit to generate electricity; and an excess hydrogen circulation pipeline for returning hydrogen discharged from the anode outlet of the fuel cell to the anode inlet of the fuel cell.

[0061] Optionally, the fuel cell uses hydrogen as fuel for an electrochemical reaction, generating high-temperature water vapor and heat of reaction while producing primary electrical energy. A first waste heat recovery module (condenser) condenses the water vapor in the high-temperature exhaust gas into high-temperature condensate, recovering a significant amount of latent heat of phase change. A second waste heat recovery module (heat exchanger) uses this high-temperature condensate to exchange heat with the low-temperature hydrogen in the cooling hydrogen circulation, transferring heat to the cooling hydrogen and raising its temperature. This heat is then used as a heat source to power the concentration cell, driving a small Carnot cycle for secondary power generation. This design achieves cascaded utilization from "chemical energy-electric energy" to "thermal energy-electric energy," significantly improving the overall system efficiency. Simultaneously, the excess hydrogen circulation pipeline returns unreacted hydrogen from the anode outlet to the inlet, improving fuel utilization and maintaining stable hydrogen concentration and pressure on the anode side, ensuring efficient fuel cell operation.

[0062] For example, Figure 6 This is a schematic diagram of a fuel cell waste heat recovery method according to an optional embodiment of the present invention, such as... Figure 6As shown, the fuel cell power generation unit uses a high-temperature fuel cell, with its anode inlet connected to a refueling hydrogen bypass and its cathode inlet connected to an air or oxygen pipeline. It also includes: a cooling hydrogen circulation pipeline for introducing non-reactive cooling hydrogen, which flows through the fuel cell stack to remove reaction heat and maintain the stack temperature; the cooling hydrogen flow rate is dynamically adjusted according to the fuel cell's heat release requirements, with the volume ratio of cooling hydrogen to reaction-consumed hydrogen controlled between 5:1 and 12:1; a secondary waste heat recovery device (condenser), connected to the fuel cell anode outlet, for condensing water vapor in the high-temperature exhaust gas into high-temperature condensate to recover the latent heat of phase change; the primary... The waste heat recovery device (heat exchanger) is connected to the outlet of the secondary waste heat recovery device to exchange heat between the high-temperature condensate and the low-temperature hydrogen in the cooling hydrogen circulation, thereby cooling the condensate and preheating the cooling hydrogen. The water collection tank is connected to the outlet of the primary waste heat recovery device to collect the condensate. The excess hydrogen circulation path sends the excess hydrogen from the anode outlet back to the anode inlet via a self-circulating pump to achieve fuel recovery. The start-up hydrogen bypass connects the high-pressure hydrogen source to the inlet of the high-pressure hydrogen chamber of the concentration cell, which is used to quickly establish the working pressure of the concentration cell during system startup, maintaining the pressure of the high-pressure hydrogen chamber at 4-6 MPa. This bypass can be closed after startup.

[0063] As an optional embodiment, the fuel cell power generation unit further includes a water collection tank for collecting condensate and replenishing the condensate to a water tank used in the water electrolysis process, forming a reversible water resource cycle.

[0064] Optionally, in the first waste heat recovery module, the high-temperature water vapor generated by the electrochemical reaction of the fuel cell is condensed into liquid water. After being cooled by heat exchange in the second waste heat recovery module, it flows into a water collection tank for temporary storage and collection. The water collection tank, acting as an intermediate buffer node, directly transports the recovered high-purity condensate to the electrolyzer tank of the hydrogen production unit, where it is reused as feedstock in the hydrogen production process. This design forms a material cycle path of "electrolysis for hydrogen production—fuel cell power generation to produce water—condensation and recovery—electrolysis reuse," eliminating the dependence on external fresh water resources in traditional hydrogen energy systems. Especially in water-scarce renewable energy-rich areas, it significantly reduces the water consumption pressure on system operation and solves the water resource bottleneck problem in green hydrogen energy storage.

[0065] As an optional embodiment, the concentration cell operates at a temperature of 170°C to 700°C, the pressure of the high-pressure hydrogen chamber of the concentration cell is 4 MPa to 6 MPa, the hydrogen partial pressure of the low-pressure hydrogen chamber of the concentration cell is 0.1 MPa to 0.5 MPa, the total pressure of the low-pressure hydrogen chamber is equal to the pressure of the high-pressure hydrogen chamber and is maintained by nitrogen, and the concentration supplement hydrogen is evenly and synchronously distributed to multiple concentration cells to form a parallel gas path network, and the output terminals of multiple concentration cells are connected end to end in sequence to form a series circuit network.

[0066] Optionally, the high-pressure hydrogen chamber of the concentration cell has a pressure of 4-6 MPa, controlled collaboratively by an expansion-compression coupling system, and rapidly established by a starting hydrogen bypass during startup. The hydrogen partial pressure in the low-pressure hydrogen chamber is 0.1-0.5 MPa, precisely controlled by adjusting the nitrogen supply through a nitrogen pressure stabilizing device. The total pressure in the low-pressure hydrogen chamber is equal to the pressure in the high-pressure hydrogen chamber (4-6 MPa), maintained by nitrogen. This pressure range ensures sufficient hydrogen partial pressure differential in the concentration cell while also considering the engineering feasibility of current high-temperature inorganic membrane materials.

[0067] The parallel gas-flow network replenishes hydrogen by uniformly and synchronously distributing the concentration difference, ensuring that each individual cell receives consistent gas flow and pressure conditions. This eliminates performance differences caused by uneven flow distribution, guarantees that each cell operates under optimal conditions, and improves the stability and consistency of power generation efficiency. The series circuit network connects the output terminals of multiple individual cells sequentially, using the principle of voltage superposition to accumulate the lower output voltage of each cell to a high voltage level that meets grid connection or load requirements. This "parallel gas-flow, series circuit" design ensures both uniform utilization of the hydrogen working fluid and efficient collection and voltage boosting of electrical energy, facilitating subsequent inverter matching and grid connection.

[0068] For example, Figure 7 This is a schematic diagram of the structure of a concentration cell power generation unit according to an optional embodiment of the present invention, such as... Figure 7 As shown, the concentration cell power generation unit comprises multiple concentration cell units, integrated using a parallel gas path and a series circuit configuration. The parallel gas path ensures uniform airflow in each unit, preventing uneven flow distribution. The series circuit configuration increases the overall output voltage, facilitating grid connection or load matching. The inlet pressure of the high-pressure hydrogen chamber is maintained within a set range, such as 2-10 MPa, preferably 4-6 MPa, through coordinated control of the hydrogen bypass and energy recovery matching system. This pressure range ensures sufficient hydrogen partial pressure difference in the concentration cell while also considering the engineering feasibility of current high-temperature inorganic membrane materials. The hydrogen concentration in the low-pressure hydrogen chamber is dynamically adjusted according to the flow rate and temperature requirements for fuel cell cooling hydrogen. The nitrogen supply is adjusted via a nitrogen pressure stabilization device to keep the hydrogen partial pressure difference across the concentration cell within the optimized range, while simultaneously meeting the cooling requirements of the fuel cell.

[0069] As an optional embodiment, the low-pressure hydrogen chamber serves as the cathode chamber of the concentration cell, and the high-pressure hydrogen chamber serves as the anode chamber of the concentration cell. The partial pressure of hydrogen in the cathode chamber is lower than the hydrogen pressure in the anode chamber. The mixed gas in the cathode chamber includes hydrogen and nitrogen, and the partial pressure of nitrogen is the difference between the total pressure of the cathode chamber and the partial pressure of hydrogen.

[0070] Optionally, the low-pressure hydrogen chamber serves as the cathode chamber, and the high-pressure hydrogen chamber serves as the anode chamber. The difference in hydrogen partial pressure between the two chambers drives ion migration to generate electricity. The hydrogen partial pressure in the cathode chamber is significantly lower than that in the anode chamber to maintain sufficient electrochemical driving force. Nitrogen gas is introduced into the cathode chamber as an inert dilution gas, forming a mixed gas system of hydrogen and nitrogen. According to Dalton's law of partial pressures, the total pressure in the cathode chamber is composed of the partial pressures of hydrogen and nitrogen, and their sum equals the total pressure of the cathode chamber.

[0071] As an optional embodiment, the concentration cell further includes: a desorption module for separating hydrogen and nitrogen in the mixed gas discharged from the low-pressure hydrogen chamber outlet of the concentration cell using hydrogen storage alloy powder to obtain pure hydrogen; and a cooling module for cooling the pure hydrogen when the temperature of the pure hydrogen is higher than a preset temperature threshold.

[0072] Optionally, the desorption module utilizes the selective hydrogen absorption and desorption characteristics of the hydrogen storage alloy powder to separate the hydrogen from the hydrogen mixture discharged from the low-pressure hydrogen chamber. This process not only removes nitrogen, an inert gas, preventing its accumulation during the cycle and thus reducing the hydrogen partial pressure and consequently the concentration cell's power generation efficiency, but also allows the hydrogen pressure to naturally drop to a low pressure through the hydrogen desorption platform pressure characteristics of the hydrogen storage alloy, creating conditions for subsequent adiabatic expansion cooling. The cooling module intervenes when the temperature of the desorbed pure hydrogen exceeds a preset threshold, cooling the hydrogen to near ambient temperature using a cryogenic hydrogen cooling system. This step is crucial because it ensures that the working fluid entering the next cycle or expansion process is at a low temperature, thereby enabling more efficient use of the temperature difference for work during the subsequent adiabatic expansion process and maintaining optimized hot-end and cold-end temperature differences in the small Carnot cycle.

[0073] For example, Figure 8 This is a schematic diagram of the internal structure of a single concentration cell according to an optional embodiment of the present invention, such as... Figure 8As shown, a single concentration cell includes: a high-pressure hydrogen chamber, serving as the anode chamber, containing high-temperature pure hydrogen heated by a heat exchanger at a pressure of 4-6 MPa and a temperature maintained at 170-700°C; a low-pressure hydrogen chamber, serving as the cathode chamber, containing a mixture of hydrogen and nitrogen gas, with a hydrogen partial pressure of 0.1-0.5 MPa, and a total pressure balanced with the high-pressure hydrogen chamber (4-6 MPa); a high-temperature proton exchange membrane, employing an inorganic proton exchange membrane capable of stable operation in the 170-600°C range, positioned between the high-pressure and low-pressure hydrogen chambers; and a nitrogen pressure stabilizing device connected to the low-pressure hydrogen chamber. The cathode chamber is used to maintain a constant total pressure, and the hydrogen concentration in the low-pressure hydrogen chamber is precisely controlled by adjusting the nitrogen flow rate. The hydrogen storage alloy powder is installed in the outlet pipeline of the low-pressure hydrogen chamber to selectively absorb hydrogen, release pure hydrogen, and isolate nitrogen. The hydrogen release platform pressure of the hydrogen storage alloy powder is selected at 0.1-0.5MPa (≤ partial pressure of hydrogen in the cathode chamber) to further reduce the hydrogen temperature after adiabatic expansion. The inlet of the high-pressure hydrogen chamber is connected to the outlet of the heat exchanger, the inlet of the low-pressure hydrogen chamber is connected to the outlet of the fuel cell waste heat recovery system, and the outlet of the hydrogen storage alloy powder is connected to the inlet of the low-temperature hydrogen cooling system.

[0074] As an optional embodiment, the low-pressure hydrogen tank is also equipped with an external delivery interface. When the external system of the hydrogen energy storage and power generation system based on the hydrogen Carnot battery has a demand for hydrogen and the hydrogen content in the low-pressure hydrogen tank reaches a preset content threshold, the external delivery interface is opened to replenish hydrogen to the external system.

[0075] Optionally, the low-pressure hydrogen tank serves as a buffer node within the system, with its pressure falling between that of the high-pressure hydrogen tank and atmospheric pressure. Here, hydrogen retains a high chemical potential and utilization value. By setting up an external output interface, the system can directly output hydrogen when the low-pressure hydrogen tank reaches a preset threshold and there is external demand, provided it meets its own power generation cycle requirements (such as replenishing cooling hydrogen, fuel hydrogen, and concentration cell working fluid). This design breaks the limitation of traditional energy storage systems that can only operate in a closed-loop "electricity-hydrogen-electricity" cycle, enabling dynamic switching between "electricity-hydrogen" and "electricity-hydrogen-electricity" modes. During periods of low grid load and abundant renewable energy, the system can increase hydrogen production and store it in the low-pressure tank. When there is external demand for hydrogen or electricity prices are high, it can choose to directly output hydrogen instead of generating electricity, thereby avoiding energy conversion losses during hydrogen fuel cell power generation (such as fuel cell efficiency loss and concentration cell heat loss), maximizing the economic value of green hydrogen.

[0076] As an optional embodiment, the pressure range of the high-pressure hydrogen tank is 20 MPa to 90 MPa, the pressure range of the high-pressure oxygen tank is 1.5 MPa to 6 MPa, and the pressure range of the low-pressure hydrogen tank is 5 MPa to 20 MPa.

[0077] Optionally, the high-pressure hydrogen tank is set at 20-90 MPa to maximize the hydrogen storage capacity per unit volume and the expansion work potential. The high-pressure hydrogen is depressurized to a low-pressure tank via a hydrogen expander, recovering a larger gradient of pressure potential energy to drive the compressor, thereby reducing the proportion of energy consumed in electrolysis compression. The high-pressure oxygen tank, with a range of 1.5-6 MPa, matches the outlet pressure of the electrolyzer (approximately 3 MPa), ensuring that oxygen can be stored without additional compression. Furthermore, it recovers considerable secondary pressure potential energy during expansion and venting, assisting in the pressurization of the fuel cell and achieving the energy storage advantage of "zero additional compression energy consumption." The low-pressure hydrogen tank, at 5-20 MPa, serves as a buffer and external delivery interface. Its lower limit of 5 MPa ensures sufficient pressure for entry into the concentration cell or external delivery, while the upper limit of 20 MPa balances storage cost and safety. Simultaneously, as the outlet of the hydrogen expander, it ensures a reasonable pressure difference before and after the expander, maximizing the conversion of the mechanical energy generated during the adiabatic expansion process into electrical energy or compression work, rather than simply dissipating heat.

[0078] As an optional embodiment, a 60kW PEM electrolyzer and a 60kW SOFC stack are used as examples to demonstrate the specific implementation of an electro-hydrogen-electric coupling energy storage and power generation system. Figure 9 This is a schematic diagram of a 60kW-class hydrogen energy storage and power generation system based on a hydrogen Carnot battery, according to an optional embodiment of the present invention. Figure 9 As shown in Table 1, the main equipment parameters are as follows:

[0079] Table 1 Equipment Parameters of the Electro-hydrogen-electro-coupled Energy Storage Power Generation System

[0080]

[0081] The PEM electrolyzer receives 60kW of renewable green electricity, has an electrolysis efficiency of 80%, and an outlet pressure of 3MPa, producing hydrogen through chemical energy.

[0082]

[0083] Hydrogen production (based on hydrogen calorific value of 33.33 kWh / kg):

[0084]

[0085] The volumetric flow rate is 1.44 kg / h ÷ 0.09 kg / m³ = 16 Nm³ / h. Hydrogen is pressurized by a compressor and stored in a 50 MPa high-pressure hydrogen tank; oxygen is directly stored in a 3 MPa high-pressure oxygen tank, requiring no additional compression energy.

[0086] Fuel cell operating temperature 800℃ (1073K), cold source temperature 25℃ (298K), Carnot efficiency:

[0087]

[0088] This optional embodiment uses a 60kW high-efficiency SOFC stack with a power generation efficiency of 60%. The fuel cell anode adopts a "partial reaction + hydrogen replenishment" working mode: only a portion of the hydrogen introduced into the stack participates in the electrochemical reaction, and the remaining hydrogen is returned to the anode inlet through the circulation loop, and the portion consumed by the reaction is replenished by the fuel hydrogen bypass.

[0089] Hydrogen gas, pressurized by an oxygen expander, enters the fuel cell, providing 48kW of hydrogen chemical energy. The fuel cell then generates electricity.

[0090]

[0091] Waste heat from fuel cells:

[0092]

[0093] Cooling hydrogen enters the fuel cell stack through an independent flow channel, absorbs the heat of reaction, and is heated to 600°C, serving as a constant-temperature heat source for the concentration cell. The cooling hydrogen needs to remove 19.2 kW of waste heat; the specific heat capacity of hydrogen is 14.5 kJ / kg·K. The cooling hydrogen inlet temperature is 30°C (engineering cooling temperature, after cooling by a low-temperature hydrogen cooling system), and the Carnot cycle cold source temperature is 25°C (ambient temperature). Both are reasonable values ​​under actual operating conditions. The cooling hydrogen mass flow rate is:

[0094]

[0095] Volumetric flow rate: 8.4 kg / h ÷ 0.09 kg / m³ = 93 Nm³ / h; Hydrogen consumption flow rate: 1.44 kg / h (16 Nm³ / h); Volume ratio of cooling hydrogen to hydrogen consumed in the reaction: 93:16 ≈ 5.8:1. A cooling hydrogen bypass supply is used to replenish cooling hydrogen in the cooling hydrogen circulation pipeline to compensate for the portion consumed in the fuel cell reaction during the cycle; the flow rate is equal to 16 Nm³ / h (i.e., the amount consumed in the reaction).

[0096] This optional embodiment employs a two-stage waste heat recovery design:

[0097] Secondary waste heat recovery (condensation): Water vapor in the fuel cell exhaust gas is condensed into condensate, recovering the latent heat of phase change. The fuel cell reaction generates approximately 13 kg / h of water, with a recovery rate of over 90%. Total latent heat recovery power:

[0098]

[0099] Primary waste heat recovery (cooling): Heat exchange is performed between the condensate and the low-temperature hydrogen in the cooling hydrogen circulation, which cools the condensate and preheats the cooling hydrogen, thus realizing a reversible cycle of water resources.

[0100] Concentration cell operating temperature: 600℃ (873K), cold source temperature: 25℃ (298K), Carnot efficiency:

[0101]

[0102] This optional embodiment uses a high-performance inorganic proton exchange membrane, with a thermoelectric conversion efficiency of 85% of the Carnot efficiency.

[0103]

[0104] The concentration cell utilizes 19.2 kW of waste heat from the fuel cell for secondary power generation.

[0105] The hydrogen expander (50MPa→20MPa) recovers approximately 3.4kW of power, and the oxygen expander (3MPa→venting) recovers approximately 0.5kW of power, for a total recovery of 3.9kW. The recovered energy is used for hydrogen concentration cell power generation.

[0106]

[0107] The concentration cell pack is integrated by connecting multiple single cells in parallel gas paths and in series circuits. The pressure in the high-pressure hydrogen chamber is 4-6 MPa, the partial pressure of hydrogen in the low-pressure hydrogen chamber is 0.1-0.5 MPa, and the total pressure in the low-pressure hydrogen chamber is maintained by nitrogen to be equal to that in the high-pressure hydrogen chamber.

[0108] The outlet pressure of the hydrogen storage alloy powder is 0.3 MPa. Adiabatic reversible expansion calculation:

[0109]

[0110]

[0111] Hydrogen gas undergoes adiabatic expansion from 600°C to 136.7°C, a temperature drop of 463.3°C. Subsequently, a cryogenic hydrogen cooling system is used for isothermal reversible heat release, cooling the hydrogen gas from 136.7°C to 25°C, with the heat released into the environment.

[0112] The overall chain efficiency was calculated using a 24-hour period as a complete cycle. The system power data is shown in Table 2.

[0113] Table 2 System Power Data Illustration

[0114]

[0115] Overall supply chain efficiency:

[0116]

[0117] By further improving the efficiency of key equipment, Table 3 is a schematic table of system optimization efficiency provided by an optional embodiment of the present invention. As shown in Table 3, the overall system efficiency can reach about 65%.

[0118] Table 3. System Optimization Efficiency Diagram

[0119]

[0120] Optimized net output:

[0121]

[0122] Optimized efficiency:

[0123]

[0124] Taking into account different working conditions and engineering implementation conditions, the overall efficiency of this system can reach 55-65%.

[0125] This optional embodiment uses a 60kW PEM electrolyzer and a 60kW SOFC stack as its core, achieving time decoupling between electrolysis and power generation through the buffering effect of a hydrogen storage tank. Its main features are as follows: Hydrogen production via electrolysis: The 60kW PEM electrolyzer uses green electricity as input, achieving an efficiency of 80%, producing 48kW of hydrogen chemical energy at an outlet pressure of 3MPa; Oxygen storage: The oxygen is directly stored in a 3MPa oxygen tank using the outlet pressure of the electrolyzer, eliminating the need for additional compression energy consumption; Pressure energy recovery: 3.4kW is recovered by the hydrogen expander (50MPa→20MPa), and 0.5kW is recovered by the oxygen expander (3MPa→venting); Fuel cell power generation: 60kW The SOFC stack has a power generation efficiency of 60%, employing a "partial reaction + hydrogen supplementation" mode, outputting 28.8kW and generating 19.2kW of waste heat. Cooling hydrogen circulation: cooling hydrogen flow rate is 93 Nm³ / h, with a volume ratio of 5.8:1 to the hydrogen consumed in the reaction (16 Nm³ / h). Two-stage waste heat recovery: secondary condensation recovers 7.5kW of latent heat and 12kg / h of water; primary preheating heats the cooling hydrogen from 30℃ to 50℃, and cools the condensate from 100℃ to 50℃. Concentration cell secondary power generation: utilizing the 19.2kW waste heat from the fuel cell, plus the recovered 3.9kW pressure potential energy from the hydrogen-oxygen storage tank, for a total input... The system has an energy output of 23.1 kW, of which 12.94 kW is generated through thermoelectric conversion in a concentration cell (efficiency 56.0%). It features adiabatic reversible expansion: hydrogen expands adiabatically from 600°C to 136.7°C, and the pressure decreases from 5 MPa to 0.3 MPa; isothermal reversible heat release: hydrogen is cooled from 136.7°C to 25°C via a low-temperature hydrogen cooling system, completing the third step of the Carnot cycle; water resource recycling: condensate recovery rate is over 90%, replenishing the electrolyzer for reuse; net system output: 40.84 kW, with an overall efficiency of 61%; optimization potential: by improving the efficiency of the fuel cell and concentration cell, it can reach 66.22%. This optional embodiment demonstrates that the overall efficiency of the electro-hydrogen-electric energy storage system can be increased from the existing 25-30% to over 60%, while simultaneously achieving zero carbon emissions and water resource recycling, showing promising application prospects.

[0126] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0127] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0128] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection of units or modules may be electrical or other forms.

[0129] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0130] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0131] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a non-volatile storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0132] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydrogen energy storage and power generation system based on a hydrogen Carnot battery, characterized in that, include: The hydrogen production unit is used to produce hydrogen and oxygen by electrolyzing water. The storage unit includes a high-pressure hydrogen tank, a high-pressure oxygen tank, and a low-pressure hydrogen tank, wherein the high-pressure hydrogen tank is used to store hydrogen, the high-pressure oxygen tank is used to store oxygen, and the low-pressure hydrogen tank is used to receive and expand the hydrogen introduced from the high-pressure hydrogen tank. A fuel cell power generation unit is used to generate electricity based on fuel hydrogen, producing first electrical energy and high-temperature waste heat, wherein the fuel hydrogen is obtained by compressing cooled hydrogen. The concentration cell power generation unit includes multiple concentration cells, each with its own anode chamber and cathode chamber. The cathode chamber contains a mixture of hydrogen and inert gas. The partial pressure of hydrogen is reduced by diluting the hydrogen with inert gas. The concentration cell power generation unit is used to generate electricity based on the high-temperature waste heat and concentration-supplemented hydrogen to produce a second electrical energy. A cooling hydrogen circulation is used to introduce cooling hydrogen that does not participate in the power generation reaction, which flows through the fuel cell power generation unit to remove the high-temperature waste heat. The flow rate of the cooling hydrogen is 5 to 12 times the flow rate of hydrogen consumed by the reaction in the fuel cell power generation unit. An expansion-compression coupling unit includes a hydrogen expander, an oxygen expander, and a first compressor. The hydrogen expander and the oxygen expander are coaxially coupled. The hydrogen expander recovers a first pressure potential energy by utilizing the pressure drop generated during the release of hydrogen from the high-pressure hydrogen tank to the low-pressure hydrogen tank. The oxygen expander recovers a second pressure potential energy by utilizing the pressure drop generated during the release of oxygen from the high-pressure oxygen tank to the atmosphere. The first pressure potential energy and the second pressure potential energy jointly drive the first compressor to compress the hydrogen in the cooling hydrogen circulation into the concentration-compensated hydrogen. The high-temperature waste heat generated by the fuel cell power generation unit serves as the constant-temperature heat source for the concentration cell power generation unit, forming a small Carnot cycle. The hydrogen production unit, the storage unit, and the fuel cell power generation unit form a large Carnot cycle. The large Carnot cycle and the small Carnot cycle are coupled in terms of matter and energy, forming a closed loop of conversion from electrical energy to chemical energy and from chemical energy to electrical energy.

2. The system according to claim 1, characterized in that, Also includes: An electrical connection unit is used to invert the first electrical energy and the second electrical energy into alternating current and input them into the target power grid.

3. The system according to claim 1, characterized in that, The hydrogen production unit also includes: The second compressor is used to compress the hydrogen obtained by electrolysis and transfer it to the high-pressure hydrogen tank for storage.

4. The system according to claim 1, characterized in that, Also includes: A hydrogen bypass is activated to generate the cooling hydrogen circulation during startup of the hydrogen energy storage and power generation system based on the hydrogen Carnot battery, and is deactivated after startup is complete.

5. The system according to claim 1, characterized in that, Also includes: A fuel hydrogen bypass is provided to input the fuel hydrogen into the fuel cell power generation unit; A hydrogen replenishment bypass is provided to replenish hydrogen to the hydrogen circulation. The flow rate of the supplemental fuel hydrogen bypass is equal to the flow rate of the supplemental cooling hydrogen bypass.

6. The system according to claim 1, characterized in that, The fuel cell power generation unit also includes: A fuel cell for generating water vapor through an electrochemical reaction based on said fuel hydrogen. The first waste heat recovery module is used to condense the water vapor into condensate. The second waste heat recovery module is used to exchange heat between the condensate and the hydrogen in the cooling hydrogen circulation, so as to raise the temperature of the hydrogen in the cooling hydrogen circulation for input into the concentration cell power generation unit to generate electricity. An excess hydrogen recirculation line is used to return hydrogen discharged from the anode outlet of the fuel cell to the anode inlet of the fuel cell.

7. The system according to claim 6, characterized in that, The fuel cell power generation unit also includes: A water collection tank is used to collect the condensate and replenish it to the water tank used in the water electrolysis process, forming a reversible water resource cycle.

8. The system according to claim 1, characterized in that, The concentration cell operates at a temperature of 170°C to 700°C. The pressure of the high-pressure hydrogen chamber of the concentration cell is 4 MPa to 6 MPa, and the hydrogen partial pressure of the low-pressure hydrogen chamber is 0.1 MPa to 0.5 MPa. The total pressure of the low-pressure hydrogen chamber is equal to the pressure of the high-pressure hydrogen chamber and is maintained by nitrogen. The concentration supplement hydrogen is evenly and synchronously distributed to the multiple concentration cells to form a parallel gas path network. The output terminals of the multiple concentration cells are connected end to end in sequence to form a series circuit network.

9. The system according to claim 8, characterized in that, The low-pressure hydrogen chamber serves as the cathode chamber of the concentration cell, and the high-pressure hydrogen chamber serves as the anode chamber of the concentration cell. The partial pressure of hydrogen in the cathode chamber is lower than the hydrogen pressure in the anode chamber. The mixed gas in the cathode chamber includes hydrogen and nitrogen, and the partial pressure of nitrogen is the difference between the total pressure of the cathode chamber and the partial pressure of hydrogen.

10. The system according to claim 8, characterized in that, The concentration cell also includes: The desorption module is used to separate hydrogen and nitrogen in the mixed gas discharged from the low-pressure hydrogen chamber outlet of the concentration cell using hydrogen storage alloy powder to obtain pure hydrogen. A cooling module is used to cool the pure hydrogen gas when the temperature of the pure hydrogen gas is greater than a preset temperature threshold.

11. The system according to claim 1, characterized in that, The low-pressure hydrogen tank is also equipped with an external delivery interface. When there is a hydrogen demand in the external system of the hydrogen energy storage and power generation system based on the hydrogen Carnot battery and the hydrogen content in the low-pressure hydrogen tank reaches a preset content threshold, the external delivery interface is opened to replenish hydrogen to the external system.

12. The system according to claim 1, characterized in that, The pressure range of the high-pressure hydrogen tank is 20 MPa to 90 MPa, the pressure range of the high-pressure oxygen tank is 1.5 MPa to 6 MPa, and the pressure range of the low-pressure hydrogen tank is 5 MPa to 20 MPa.

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