Reversible solid oxide cell energy storage system and method
By combining a reversible solid oxide battery system with a molten salt thermal storage device, and using NH3 as the energy storage medium, efficient storage and conversion of electrical and thermal energy are achieved, solving the problem of difficult storage of electrical and thermal energy and improving the energy utilization efficiency and safety of the system.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHANGHAI INSTITUTE OF APPLIED PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2023-08-16
- Publication Date
- 2026-07-03
AI Technical Summary
Existing technologies make it difficult to store electrical energy efficiently, especially when the volatility of new energy power generation increases. Electrical and thermal energy storage is difficult, and existing solutions suffer from problems such as large energy loss, numerous side reactions, and complex gas utilization.
A reversible solid oxide battery system is adopted, using NH3 as the energy storage medium. The conversion of electrical energy into chemical energy is achieved through the reverse reaction of H-SOFC and H-SOEC. Combined with a molten salt thermal storage device for thermal energy storage and management, a closed gas circulation system is formed to achieve efficient storage and conversion of electrical and thermal energy.
It achieves efficient storage and conversion of electrical and thermal energy, reduces grid load fluctuations, improves system energy utilization efficiency, reduces system noise and power consumption, and enhances safety and thermal neutrality of the system.
Smart Images
Figure CN117254083B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to electrochemical energy storage technology, and more specifically to a reversible solid oxide battery energy storage system and method. Background Technology
[0002] The utilization of electricity is time-sensitive, while its production is not, creating a contradiction that generates the need for electricity storage. Furthermore, the increasing installed capacity of new energy power generation and its inevitable fluctuations in power generation exacerbate this demand.
[0003] CN114221445A discloses a wave power generation energy storage system and an energy storage method for operating the system. It utilizes ocean waves and wind energy to generate electricity, which is then used for water electrolysis to produce hydrogen and pressure swing adsorption (PSA) to produce nitrogen. The resulting hydrogen and nitrogen are then synthesized into ammonia, which is stored. The stored ammonia is then converted into electricity through a fuel cell power generation system. Clearly, this scheme first uses an electrolytic cell to electrolyze water to produce hydrogen, and then uses the resulting hydrogen and nitrogen to produce ammonia through a traditional ammonia synthesis process. Here, the nitrogen comes from air, and the hydrogen comes from water electrolysis. The process is lengthy, with significant energy loss in the intermediate steps and low electrolysis efficiency.
[0004] CN115821303A discloses a renewable hydrogen-ammonia energy storage system coupled with a SOFC. Its energy storage section includes a proton exchange membrane electrolyzer for a water electrolysis hydrogen production subsystem, a cryogenic air separation nitrogen production subsystem, and an ammonia synthesis process. The energy release section includes a solid oxide ammonia fuel cell process. The energy storage section's start-up phase involves using surplus power from the generator to perform water electrolysis for hydrogen production. The energy release process uses ammonia produced in the energy storage section as fuel to drive the fuel cell and release electrical energy. Here, the nitrogen is derived from air, and the hydrogen is derived from water electrolysis. This scheme requires a continuous supply of air to participate in the reaction. The air compressor has power consumption and noise issues, and the participation of air produces water vapor and oxygen as byproducts. The gases need to be dried and purified before reuse. Summary of the Invention
[0005] To address the problems of difficulty in storing electrical energy in the prior art, the present invention provides a reversible solid oxide battery energy storage system and method.
[0006] The reversible solid oxide battery energy storage system according to the present invention includes an RSOC system, a molten salt thermal storage device, and a self-circulating gas closed-loop system. The RSOC system consists of SOFC and SOEC. The SOFC is an H-SOFC with NH3 as the energy storage medium to define the power generation mode, and the SOEC is an H-SOEC with NH3 as the energy storage medium to define the electrolysis mode. The heat absorption and heat generation in different modes of power generation and electrolysis are coupled with the molten salt thermal storage device to store and redistribute thermal energy during operation, thereby achieving thermal neutrality of the system. The self-circulating gas closed-loop system supplies NH3 to the H-SOFC and H2 and N2 to the H-SOEC through the recycling of hydrogen-ammonia conversion.
[0007] Preferably, in the RSOC system, the decomposition and synthesis of NH3 involve changes in chemical energy, linking chemical energy with electrical energy, thereby forming a cycle of electrical energy storage and release, and regulating the peak and valley of electrical energy.
[0008] Preferably, in an H-SOFC, a mixture of NH3 and H2 is introduced into the anode and H2 is introduced into the cathode, resulting in an electrochemical reaction that outputs electrical energy.
[0009] Preferably, in H-SOEC, H2 is introduced into the anode and N2 is introduced into the cathode, and an electrochemical reaction is carried out to synthesize NH3 by applying voltage.
[0010] Preferably, H-SOFC releases heat during operation, and the released heat energy is stored in a molten salt heat storage device, while H-SOEC absorbs heat during operation, and the heat energy stored in the molten salt heat storage device is used for its own purposes.
[0011] Preferably, the self-circulating gas closed-loop system includes a first container for storing NH3, a second container for storing H2, and a third container for storing N2. The first container is connected between the H-SOFC and the H-SOEC via a first closed-loop pipeline to supply NH3 to the H-SOFC, the second container is connected between the H-SOFC and the H-SOEC via a second closed-loop pipeline to supply H2 to the H-SOEC, and the third container is connected between the H-SOFC and the H-SOEC via a third closed-loop pipeline to supply N2 to the H-SOEC.
[0012] Preferably, H-SOEC utilizes N2 and H2 produced in H-SOFC and stored in the second and third containers to synthesize NH3.
[0013] Preferably, H-SOFC decomposes NH3 synthesized from H-SOEC into N2 and H2 as fuel.
[0014] Preferably, H-SOEC achieves thermal neutrality by utilizing the thermal energy stored in the molten salt regenerator by H-SOFC.
[0015] According to the reversible solid oxide battery energy storage method of the present invention, during peak electricity demand, the power generation mode is activated by H-SOFC to supplement the power utilization gap and reduce the load pressure on the power grid; during off-peak electricity demand, the excess power is utilized by H-SOEC in electrolysis mode to produce NH3.
[0016] The reversible solid oxide battery energy storage system and method of the present invention addresses the difficulties in storing and transporting electrical and thermal energy. It proposes a reversible solid oxide fuel cell system using NH3 as the energy storage medium and ammonia fuel to link and convert the changes in chemical energy during the decomposition and synthesis of NH3 with electrical energy, achieving effective electrical energy storage and mitigating grid load fluctuations. Simultaneously, a molten salt thermal storage device is used to store the thermal energy released by the system and to provide heat for the system during heat absorption, achieving thermal energy storage and enabling the system to achieve thermal neutrality, thereby improving the system's energy utilization efficiency. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the overall structure of a reversible solid oxide battery energy storage system according to a preferred embodiment of the present invention.
[0018] Figure 2 yes Figure 1 A schematic diagram of the working principle of a proton-type solid oxide fuel cell.
[0019] Figure 3 yes Figure 1 The working principle diagram of a solid oxide fuel electrolyzer.
[0020] Figure 4 yes Figure 1 The working principle diagram of a self-circulating gas closed-loop system. Detailed Implementation
[0021] The preferred embodiments of the present invention are given below with reference to the accompanying drawings and described in detail.
[0022] like Figure 1As shown, a reversible solid oxide battery energy storage system according to a preferred embodiment of the present invention includes a reversible solid oxide cell (RSOC) system, a molten salt thermal storage device, and a self-circulating gas closed-loop system. The RSOC system comprises a solid oxide fuel cell (SOFC) and a solid oxide fuel electrolyzer. The system comprises a self-circulating gas closed-loop system (SOEC) and a molten salt thermal storage device (SOFC) to achieve heat recycling. SOFC is a proton-type solid oxide fuel cell (H-SOFC) based on ammonia fuel to define the power generation mode of RSOC. SOEC is a proton-type solid oxide fuel cell (H-SOEC) based on ammonia fuel to define the electrolysis mode of RSOC. The self-circulating gas closed-loop system includes a first container (e.g., NH3 bottle) for storing ammonia (NH3), a second container (e.g., H2 bottle) for storing nitrogen (H2), and a third container (e.g., N2 bottle) for storing hydrogen (N2). The first container is connected between H-SOFC and H-SOEC through a first closed-loop pipeline to supply NH3 to H-SOFC. The second container is connected between H-SOFC and H-SOEC through a second closed-loop pipeline to supply H2 to H-SOEC. The third container is connected between H-SOFC and H-SOEC through a third closed-loop pipeline to supply N2 to H-SOEC.
[0023] In the RSOC system, NH3 serves as the energy storage medium. The decomposition and synthesis of NH3 involve changes in chemical energy, linking chemical energy with electrical energy to form a cycle of energy storage and release, thus regulating peak and valley energy levels. In other words, the RSOC system of the reversible solid oxide battery energy storage system according to this invention has high energy density and advanced capabilities for direct and efficient decomposition and synthesis of NH3. Both the decomposition and synthesis reactions of NH3 are simple and without side reactions. Utilizing the changes in chemical energy during the decomposition and synthesis of NH3, a conversion between electrical energy and chemical energy is formed, realizing a cycle of energy storage and release, and regulating peak and valley energy levels. It is particularly noteworthy that, unlike the phase change in existing technologies, this invention proposes utilizing the chemical energy of NH3, achieving highly efficient energy storage and release through the decomposition and synthesis process of NH3 with no side reactions and high energy density. Based on this, this invention proposes for the first time the combination of H-SOFC and H-SOEC, enabling efficient energy conversion, storage, and utilization at relatively low temperatures, contributing to improved sustainability and flexibility of energy systems and promoting the development of clean energy technologies.
[0024] In the RSOC system, H-SOFCs release heat during operation, and the released thermal energy is stored in the molten salt thermal storage device. H-SOECs absorb heat during operation, and the thermal energy stored in the molten salt thermal storage device is utilized. The heat absorption and generation during different modes of power generation and electrolysis are coupled with the molten salt thermal storage device, storing and redistributing thermal energy during operation to achieve thermal neutrality of the system. In other words, the RSOC system of the reversible solid oxide battery energy storage system according to the present invention, by coupling the thermal storage function of the molten salt thermal storage device, utilizes the heat release during SOFC mode to the heat absorption during SOEC mode, enabling efficient utilization of the system's thermal energy, thereby achieving thermal neutrality of the energy storage system and improving the system's energy storage efficiency.
[0025] The reversible solid oxide battery energy storage method according to the present invention includes: during peak electricity demand, activating the power generation mode through H-SOFC to supplement the power utilization gap and reduce the load pressure on the power grid; during off-peak electricity demand, utilizing the excess power in electrolysis mode through H-SOEC to produce NH3.
[0026] H-SOFC is composed of stacked solar cells. Each solar cell consists of an anode channel, an anode functional layer, an electrolyte, a cathode functional layer, and a cathode channel. Figure 2 As shown, NH3 is decomposed into N2 and H2 using an electrochemical reaction. The specific operation involves introducing a mixture of NH3 and H2 into the anode channel and H2 into the cathode channel, where the electrochemical reaction of equation (1) occurs in the fuel cell stack, outputting electrical energy and releasing heat.
[0027] SOFC cathode: 6H + →3H2-6e -
[0028] SOFC anode: 2NH3 → N2 + 6H + +6e - (1)
[0029] H-SOEC is composed of stacked solar cells. Each solar cell consists of an anode channel, an anode functional layer, an electrolyte, a cathode functional layer, and a cathode channel. Figure 3 As shown, this is the reverse reaction of H-SOFC, which uses an electrochemical reaction to synthesize NH3 from the N2 and H2 produced in H-SOFC, without the side reaction NO. X The specific operation involves introducing H2 into the anode channel and N2 into the cathode channel, applying voltage, and causing the electrochemical reaction of formula (2) to occur in the fuel cell stack, synthesizing NH3 and absorbing heat.
[0030] Cathode of SOEC: N2 + 6H + +6e - →2NH3
[0031] SOEC anode: 3H2-6e - →6H + (2)
[0032] like Figure 4 As shown, the NH3 produced by H-SOEC is stored in an NH3 bottle and can be used by H-SOFC through a first closed-loop pipeline. The exhaust gases of H-SOFC are H2 and N2, which are stored in H2 and N2 bottles respectively and can be reused by the next round of H-SOEC through second and third closed-loop pipelines, thus completing the gas cycle. In particular, the gas utilization method in the reversible solid oxide battery energy storage system according to the present invention is feeding and product recycling. The gas system is a closed system. Therefore, after the initial operation, there is no need to supply gas to the system again, there is no material exchange with the ambient atmosphere, there is no risk of gas leakage, and the safety performance is high. Compared with the existing technology where N2 is derived from the air, the present invention provides the recycling of hydrogen-ammonia conversion, and the N2 is automatically generated by the system without the participation of air.
[0033] Compared to existing technologies that involve air in the reaction and produce byproducts, the gas circulation system of the reversible solid oxide battery energy storage system according to the present invention, which serves as the energy storage medium, is a closed system that does not require repeated purification and does not cause additional power consumption.
[0034] Back Figure 1 During peak power consumption periods, the system needs to output electrical energy to compensate for the power consumption of electrical appliances. This is achieved by starting the power generation mode through H-SOFC, combined with... Figure 2 NH3 is directly used as fuel and introduced into the anode channel of the battery, while H2 is used as an auxiliary gas and introduced into the cathode channel. Through an electrochemical reaction, NH3 decomposes into H2 and N2. N2 flows out from the anode channel and is collected in a gas storage cylinder (see [link to documentation]). Figure 4 In the cathode channel, H2 flows out and is collected in the gas storage cylinder (see [link]). Figure 4 (in) Back to Figure 1 During periods of low electricity demand, the system is switched to electrolysis mode, and excess electricity is fed into the H-SOEC. N2 and H2, produced and stored in the gas storage cylinder of the H-SOFC, are then fed into the cathode and anode of the H-SOEC, respectively. Figure 3 Through an electrochemical reaction, N2 and H2 are directly synthesized into NH3, which is then discharged through the cathode channel without any side reactions. The discharged NH3 is collected in a gas storage bottle (see [link]). Figure 4 This is used by H-SOFC in the next cycle.
[0035] Back Figure 1During peak electricity demand periods, H-SOFCs release electrical and thermal energy during operation. The electrical energy is used to supplement power generation, while the thermal energy is stored in the molten salt thermal storage device. During off-peak electricity demand periods, H-SOECs absorb electrical and thermal energy. The surplus electricity in the grid can be used to maintain the electrolysis of the stack, and the thermal energy stored in the molten salt thermal storage device of the H-SOFC can be used to heat the H-SOEC stack. Specifically, the operation of H-SOFCs is an exothermic process, while the operation of H-SOECs is an endothermic process. Utilizing the thermal storage capacity of the molten salt thermal storage device, the high-quality waste heat released during the operation of H-SOFCs is stored for use in the operation of H-SOECs, achieving thermal neutrality, or it can be used as a high-quality heat source to supply other heat-consuming devices, improving the system's thermal utilization and energy storage efficiency.
[0036] Thus, the reversible solid oxide battery energy storage method of the present invention can realize flexible energy conversion from electrical energy to chemical energy and back to electrical energy, and has broad development space and application prospects. The reversible solid oxide battery energy storage system of the present invention utilizes the changes in chemical energy and the easy storage characteristics of specific chemical substances to achieve the cycle of electrical energy-chemical energy-electrical energy through an RSOC device, thereby achieving efficient storage of electrical energy; simultaneously, it also achieves the storage and redistribution of system thermal energy through a molten salt thermal storage device, thereby achieving thermal neutrality of the system. This solves the problem of the difficulty in storing electrical and thermal energy, and enables the environmentally friendly storage and transportation of waste electricity during off-peak hours and the high-quality waste heat from power generation devices, providing power and heat during peak hours. This achieves efficient energy conversion from electricity to electricity and from heat to heat, and has the advantages of being all-solid-state, highly efficient, fuel-flexible, and low-noise, which can greatly promote the clean development of the energy system and help achieve the "dual carbon" goal.
[0037] Furthermore, since H-SOFC and H-SOEC are reverse reactions, according to the law of conservation of mass, the amount of gas generated and consumed will not change. Therefore, during the circulation process, there is no need to exchange matter with the external environment. The circulation path of NH3 decomposition and synthesis can be made into a closed path, eliminating the risk of gas leakage and improving the safety of the system.
[0038] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. That is, all simple and equivalent changes and modifications made based on the claims and description of this invention fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.
Claims
1. A reversible solid oxide battery energy storage system, characterized in that, This reversible solid oxide battery energy storage system includes an RSOC system, a molten salt thermal storage device, and a self-circulating gas closed-loop system. The RSOC system consists of SOFC and SOEC. The SOFC is an H-SOFC using NH3 as the energy storage medium to define the power generation mode, and the SOEC is an H-SOEC using NH3 as the energy storage medium to define the electrolysis mode. The heat absorption and generation during the different power generation and electrolysis modes are coupled with the molten salt thermal storage device, storing and redistributing thermal energy during operation. The H-SOFC releases heat during operation, and the released thermal energy is stored in the molten salt thermal storage device. The H-SOEC... During operation, the system absorbs heat, and the thermal energy stored in the molten salt thermal storage device is used for its operation. The H-SOEC utilizes the thermal energy stored in the molten salt thermal storage device of the H-SOFC to achieve thermal neutrality of the system. The self-circulating gas closed-loop system supplies NH3 to the H-SOFC and supplies H2 and N2 to the H-SOEC through the recycling of hydrogen-ammonia conversion. The H-SOEC is the reverse reaction of the H-SOFC, using the N2 and H2 produced in the H-SOFC to synthesize NH3. The H-SOFC decomposes the NH3 synthesized from the H-SOEC into N2 and H2 as fuel. After the initial operation, there is no need to supply gas to the system.
2. The reversible solid oxide battery energy storage system according to claim 1, characterized in that, In an H-SOFC, a mixture of NH3 and H2 is introduced into the anode and H2 is introduced into the cathode, resulting in an electrochemical reaction that outputs electrical energy.
3. The reversible solid oxide battery energy storage system according to claim 1, characterized in that, In H-SOEC, H2 is introduced into the anode and N2 into the cathode, and an electrochemical reaction occurs when a voltage is applied to synthesize NH3.
4. The reversible solid oxide battery energy storage system according to claim 1, characterized in that, The self-circulating gas closed-loop system includes a first container for storing NH3, a second container for storing H2, and a third container for storing N2. The first container is connected between the H-SOFC and the H-SOEC via a first closed-loop pipeline to supply NH3 to the H-SOFC. The second container is connected between the H-SOFC and the H-SOEC via a second closed-loop pipeline to supply H2 to the H-SOEC. The third container is connected between the H-SOFC and the H-SOEC via a third closed-loop pipeline to supply N2 to the H-SOEC.
5. The energy storage method of the reversible solid oxide battery energy storage system according to any one of claims 1-4, characterized in that, During peak electricity demand periods, H-SOFC is used to activate the power generation mode to supplement the power utilization gap and reduce the load pressure on the power grid; during off-peak electricity demand periods, H-SOEC is used in electrolysis mode to utilize excess electricity to produce NH3.