Energy storage system

Abstract

The utility model provides an energy storage system which comprises an energy storage module which comprises an energy storage flow path, in the energy storage flow path, a first working medium output by a first cavity is sequentially compressed, cooled and subjected to latent heat exchange with a second working medium in a phase change heat exchanger to be converted into a liquid state from a gas state, the first working medium is conveyed to a first working medium liquid storage tank, and electric energy is converted into pressure energy; and the energy release module comprises an energy release flow path, in the energy release flow path, a first working medium output by the first working medium liquid storage tank is subjected to latent heat exchange with a second working medium in the phase change heat exchanger in sequence and is converted into a gas state from a liquid state, and the first working medium is input into the first cavity after being heated and expanded, so that pressure energy is converted into electric energy. The first working medium and the second working medium exchange phase change latent heat in the reciprocal gas-liquid conversion process to achieve reciprocal phase state conversion, so that an external cold source does not need to be arranged in the liquefaction process of the first working medium, an external heat source does not need to be arranged in the gasification process, and therefore the energy storage system gets rid of limitation of external cold source or heat source conditions.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, specifically to an energy storage system. Background Technology

[0002] Compressed working fluid energy storage is an advanced new physical energy storage technology. The working fluids that can be selected include air, carbon dioxide, water vapor, etc. Among them, carbon dioxide working fluid has received much attention from the industry due to its excellent physical properties and its ability to be combined with CCUS, which has the dual effect of energy storage and carbon dioxide sequestration. Technology research and development and small-scale pilot demonstrations have been widely carried out.

[0003] However, the existing liquefied carbon dioxide (LCC) energy storage technology requires external environmental cold source conditions to liquefy the carbon dioxide working fluid for high-density storage to reduce the cost of high-pressure storage facilities. During the energy release process, external heat source conditions are also required to vaporize the carbon dioxide working fluid. It is difficult for typical plant sites to simultaneously meet the above-mentioned cold and heat source conditions. Insufficient cold or heat source conditions will reduce the energy storage efficiency of the system to <60%, which will cause a major obstacle to the site selection and construction of liquefied carbon dioxide energy storage power plants. Furthermore, the temperature of the environmental cold source is often high, and the corresponding carbon dioxide liquefaction pressure is high (>8MPa), which will drastically increase the cost of high-pressure storage facilities and reduce safety. Utility Model Content

[0004] In view of this, this application provides an energy storage system that achieves reversible phase transition by exchanging latent heat of phase change between a first working fluid and a second working fluid during reversible gas-liquid transition processes. In this way, the liquefaction process does not require an external cold source and the gasification process does not require an external heat source, thereby freeing the energy storage system from the limitations of external cold or heat source conditions.

[0005] To achieve the above objectives, this application provides the following technical solution:

[0006] An energy storage system, comprising:

[0007] A gas storage tank includes a first chamber and a second chamber, wherein the first chamber is used to store a first gaseous working fluid, and the second chamber is used to store a second gaseous working fluid.

[0008] A first working fluid liquid storage tank is used to store the first working fluid in liquid form.

[0009] The second working fluid liquid storage tank is used to store the liquid second working fluid;

[0010] An energy storage module includes an energy storage flow path and a cooling flow path. The energy storage flow path includes, in series, the outlet of the first chamber, a first working fluid compressor, a heat path of a first heat exchanger, a heat path of a phase change heat exchanger, and the inlet of the first working fluid liquid storage tank. This allows the first working fluid output from the first chamber to be compressed by the first working fluid compressor, cooled by heat exchange in the heat path of the first heat exchanger, and to undergo latent heat exchange with the second working fluid in the phase change heat exchanger, changing from a gaseous state to a liquid state, before being transported to the first working fluid liquid storage tank, thereby converting electrical energy into pressure energy.

[0011] The cooling flow path includes the outlet of the second working fluid liquid storage tank, an expansion valve, the phase change heat exchanger, the first cold path of the first heat exchanger, the second working fluid expander, the second cold path of the first heat exchanger, and the inlet of the second chamber, connected in series. This allows the second working fluid output from the second working fluid liquid storage tank to sequentially exchange latent heat with the first working fluid in the phase change heat exchanger, changing from a liquid to a gaseous state; then undergoing heat exchange and temperature increase through the first cold path of the first heat exchanger; expanding through the second working fluid expander; and undergoing heat exchange and temperature increase through the second cold path of the first heat exchanger before being input into the second chamber. This achieves the cooling of the energy storage flow path by the cooling flow path.

[0012] The energy release module includes an energy release flow path and a heating flow path. The energy release flow path includes the outlet of the first working fluid liquid storage tank, the cold path of the phase change heat exchanger, the cold path of the second heat exchanger, the first working fluid expander, and the inlet of the first chamber, which are connected in series. This allows the first working fluid output from the first working fluid liquid storage tank to exchange latent heat with the second working fluid in the phase change heat exchanger, change from liquid to gas, undergo heat exchange and temperature increase through the cold path of the second heat exchanger, expand through the first working fluid expander, and be input into the first chamber, thereby realizing the conversion of pressure energy into electrical energy.

[0013] The heating flow path includes, in series, the outlet of the second chamber, the first hot path of the second heat exchanger, the second working fluid compressor, the second hot path of the second heat exchanger, the phase change heat exchanger, and the inlet of the second working fluid liquid storage tank. This allows the second working fluid output from the second chamber to undergo heat exchange and cooling via the first hot path of the second heat exchanger, compression via the second working fluid compressor, heat exchange and cooling via the second hot path of the second heat exchanger, and latent heat exchange with the first working fluid in the phase change heat exchanger, changing from a gaseous phase to a liquid phase, before being input into the second working fluid liquid storage tank. This achieves the heating of the energy release flow path by the heating flow path.

[0014] Optionally, the above energy storage system also includes a heat storage device, which is used to recover heat from the energy storage flow path and release heat to the energy release flow path.

[0015] Optionally, in the above energy storage system, the heat storage device includes a third heat exchanger, a fourth heat exchanger, a cold tank, and a hot tank, and the heat storage device stores a heat storage medium; the hot circuit of the third heat exchanger is connected in series between the first working fluid compressor and the hot circuit of the first heat exchanger; the cold circuit of the fourth heat exchanger is connected in series between the first working fluid expander and the cold circuit of the second heat exchanger; the cold tank is connected in series between the cold circuit inlet of the third heat exchanger and the hot circuit outlet of the fourth heat exchanger; the hot tank is connected in series between the cold circuit outlet of the third heat exchanger and the hot circuit inlet of the fourth heat exchanger.

[0016] During energy storage, the heat storage medium is output from the cold tank and heated through the cold path of the third heat exchanger before entering the hot tank; during energy release, the heat storage medium is output from the hot tank and cooled through the hot path of the fourth heat exchanger before entering the cold tank.

[0017] Optionally, in the above energy storage system, the first working fluid expander is used to drive the motor to generate electricity, the motor is used to drive the first working fluid compressor to work, and the first working fluid expander, the motor and the first working fluid compressor are coaxially connected.

[0018] Optionally, in the above energy storage system, the gas storage tank is configured as a flexible airbag structure, the flexible airbag structure including a first chamber that can be flexibly deformed and a second chamber that can be flexibly deformed.

[0019] Optionally, in the above energy storage system, the first working medium is carbon dioxide and the second working medium is ammonia.

[0020] Optionally, in the above energy storage system, the heat storage medium is heat transfer oil, molten salt, or high-pressure water.

[0021] This application provides an energy storage system in which, during energy storage, a first working fluid is output from a first chamber to an energy storage flow path, and a second working fluid is output from a second working fluid liquid storage tank to a cooling flow path. The first working fluid in the energy storage flow path is sequentially compressed, cooled, and liquefied before being input into the first working fluid liquid storage tank. The second working fluid in the cooling flow path is sequentially vaporized, heated, expanded, and heated again before being input into the second chamber. The first and second working fluids exchange latent heat in a phase change heat exchanger, achieving liquefaction of the first working fluid and vaporization of the second working fluid. The first and second working fluids also exchange heat in a first heat exchanger, achieving cooling of the first working fluid and heating of the second working fluid. Thus, the first and second working fluids exchange latent heat of phase change in the phase change heat exchanger to achieve phase transition, thereby avoiding the need for an external cold source during the liquefaction of the first working fluid. Furthermore, the vaporized second working fluid is also used to cool the first working fluid during energy storage, fully utilizing the internal cooling capacity of the energy storage system and achieving full energy utilization.

[0022] During energy release, the first working fluid is output from the first working fluid liquid storage tank to the energy release flow path, and the second working fluid is output from the second chamber to the heating flow path. The first working fluid in the energy release flow path is sequentially vaporized, heated, and expanded to generate electricity before being input into the first chamber. The second working fluid in the heating flow path is sequentially cooled, compressed, cooled again, and liquefied before being input into the second working fluid liquid storage tank. The first and second working fluids exchange latent heat in a phase change heat exchanger, achieving vaporization of the first working fluid and liquefaction of the second working fluid. The first and second working fluids also exchange heat in a second heat exchanger, achieving heating of the first working fluid and cooling of the second working fluid. Thus, the first and second working fluids exchange latent heat of phase change in the phase change heat exchanger to achieve phase transition, thereby avoiding the need for an external heat source during the vaporization of the first working fluid. Furthermore, during energy release, the second working fluid is also used to heat the first working fluid, fully utilizing the heat within the energy storage system to achieve full energy utilization.

[0023] In summary, the first and second working fluids exchange latent heat of phase change during the reversible gas-liquid transition process to achieve the reversible phase transition. This means that the liquefaction process of the first working fluid does not require an external cold source, and the gasification process does not require an external heat source, thus freeing the energy storage system from the limitations of external cold or heat source conditions. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0025] Figure 1 This is a schematic diagram of an energy storage system provided in an embodiment of this application.

[0026] exist Figure 1 middle:

[0027] 1. Gas storage compartment; 101. First chamber; 102. Second chamber;

[0028] 2. First working fluid liquid storage tank; 3. Second working fluid liquid storage tank; 4. Energy storage flow path; 5. Cooling flow path; 6. First working fluid compressor; 7. First heat exchanger; 8. Phase change heat exchanger; 9. Expansion valve; 10. Second working fluid expander; 11. Energy release flow path; 12. Heating flow path; 13. Second heat exchanger; 14. First working fluid expander; 15. Second working fluid compressor; 16. Heat storage device; 17. Third heat exchanger; 18. Fourth heat exchanger; 161. Cold tank; 162. Hot tank; 19. Motor. Detailed Implementation

[0029] This application provides an energy storage system that achieves reversible phase transitions by exchanging latent heat of phase change between a first working fluid and a second working fluid during reversible gas-liquid transitions. In this way, the liquefaction process does not require an external cold source and the gasification process does not require an external heat source, thereby freeing the energy storage system from the limitations of external cold and heat source conditions.

[0030] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0031] like Figure 1 As shown in the embodiment of this application, an energy storage system is provided. During energy storage, a first working fluid is output from a first chamber 101 to an energy storage flow path 4, and a second working fluid is output from a second working fluid liquid storage tank 3 to a cooling flow path 5, so that the second working fluid cools the first working fluid. Specifically, in the energy storage flow path 4, the first working fluid is compressed by the first working fluid compressor 6, cooled by exchanging heat with the second working fluid through the hot path of the first heat exchanger 7, and changed from a gaseous state to a liquid state by exchanging latent heat with the second working fluid through the hot path of the phase change heat exchanger 8 before being input into the first working fluid liquid storage tank 2, converting electrical energy into pressure energy and storing it. At the same time, the second working fluid is output from the second working fluid liquid storage tank 3 to the cooling flow path 5 and is expanded and depressurized by the expansion valve 9, changed from a liquid state to a gaseous state by exchanging latent heat with the first working fluid in the phase change heat exchanger 8, heated by exchanging heat with the second working fluid through the first cold path of the first heat exchanger 7, expanded by the second working fluid expander 10, heated by exchanging heat with the first working fluid again through the second cold path of the first heat exchanger 7 before being input into the second chamber 102. It can be seen that the first working fluid and the second working fluid exchange latent heat in the phase change heat exchanger 8. The first working fluid changes from a gaseous state to a liquid state, and the second working fluid changes from a liquid state to a gaseous state. In the first heat exchanger 7, the second working fluid absorbs the heat of the first working fluid to cool the first working fluid.

[0032] During energy release, the first working fluid is output from the first working fluid liquid storage tank 2 to the energy release flow path 11, and the second working fluid is output from the second chamber 102 to the heating flow path 12, so that the second working fluid heats the first working fluid. Specifically, the first working fluid sequentially undergoes latent heat exchange with the second working fluid through the cold path of the phase change heat exchanger 8, changing from a liquid to a gaseous state; it then undergoes heat exchange with the second working fluid through the cold path of the second heat exchanger 13, increasing its temperature; it expands and generates electricity through the first working fluid expander 14, and is input into the first chamber 101, converting pressure energy into electrical energy. At the same time, the second working fluid is output from the second chamber 102 and sequentially undergoes heat exchange with the first working fluid through the first hot path of the second heat exchanger 13, decreasing its temperature; it then undergoes compression through the second working fluid compressor 15, decreasing its temperature through the second hot path of the second heat exchanger 13, and finally undergoes latent heat exchange with the first working fluid in the phase change heat exchanger 8, changing from a gaseous state to a liquid state, and is input into the second working fluid liquid storage tank 3. It can be seen that the first working fluid and the second working fluid exchange latent heat in the phase change heat exchanger 8. The first working fluid changes from a liquid phase to a gaseous phase, and the second working fluid changes from a gaseous phase to a liquid phase. In the second heat exchanger 13, the second working fluid releases heat to the first working fluid to heat the first working fluid.

[0033] In summary, the first and second working fluids exchange latent heat of phase change during their reversible gas-liquid transitions to achieve these phase transitions. This avoids the need for an external cold source during the liquefaction of the first working fluid and an external heat source during its vaporization, thus freeing the energy storage system from the limitations of external cold and heat sources. In addition, the second working fluid is used to cool the first working fluid during energy storage and to heat the first working fluid during energy release, making full use of the internal cold and heat of the energy storage system and achieving full utilization of energy.

[0034] In addition, the energy storage system also includes a heat storage device 16, which is used to recover heat from the energy storage flow path 4 and release heat to the energy release flow path 11. It can be understood that when storing energy, the heat storage device 16 absorbs heat from the first working medium and stores the heat; when releasing energy, it releases the previously stored heat back to the first working medium. In this way, the heat of the energy storage system is fully utilized, and the energy storage efficiency is improved.

[0035] The heat storage device 16 includes a third heat exchanger 17, a fourth heat exchanger 18, a cold tank 161, and a hot tank 162. The heat storage device 16 stores a heat storage medium. The hot path of the third heat exchanger 17 is connected in series between the hot paths of the first working fluid compressor 6 and the first heat exchanger 7. The cold path of the fourth heat exchanger 18 is connected in series between the cold paths of the first working fluid expander 14 and the second heat exchanger 13. The cold tank 161 is connected in series between the cold path inlet of the third heat exchanger 17 and the hot path outlet of the fourth heat exchanger 18. The hot tank 162 is connected in series between the cold path outlet of the third heat exchanger 17 and the hot path inlet of the fourth heat exchanger 18. During energy storage, the heat storage medium is output from the cold tank 161 and heated by heat exchange through the cold path of the third heat exchanger 17 before entering the hot tank 162. During energy release, the heat storage medium is output from the hot tank 162 and cooled by heat exchange through the hot path of the fourth heat exchanger 18 before entering the cold tank 161. It can be seen that the heat storage device 16 has a simple composition and a simple and reliable heat storage principle.

[0036] In some optional embodiments, the first working fluid expander 14 is used to drive the motor 19 to generate electricity, and the motor 19 is used to drive the first working fluid compressor 6. The first working fluid expander 14, the motor 19, and the first working fluid compressor 6 are coaxially connected. In this way, a direct drive method between the expander and the compressor is achieved, reducing intermediate links, reducing energy loss in intermediate transmission, improving efficiency, and also saving installation space, making the entire device more compact.

[0037] In some optional embodiments, the gas storage 1 is configured as a flexible airbag structure, which includes a first chamber 101 capable of flexible deformation and a second chamber 102 capable of flexible deformation. As described above, during energy storage, the first working medium is output from the first chamber 101, and the second working medium is input into the second chamber 102. During the energy release phase, the first working medium is input into the first chamber 101, and the second working medium is output from the second chamber 102. Thus, the two working media enter and exit in turn, thereby ensuring that the space of the gas storage 1 is always effectively utilized without the need for additional investment or floor space for a new gas storage 1.

[0038] In some other alternative embodiments, the gas storage tank 1 can be configured as a rigid structure, with the interior of the rigid structure divided into two sets of flexible deformable chambers by a flexible and deformable airbag structure.

[0039] In some optional embodiments, the first working medium is carbon dioxide and the second working medium is ammonia. The latent heat exchange between carbon dioxide and ammonia is a highly efficient energy utilization method, which can realize the effective conversion and utilization of energy during the phase change process of matter.

[0040] In some optional embodiments, the heat storage medium is heat transfer oil, molten salt, or high-pressure water. Heat transfer oil, as a heat storage medium, requires no fuel replenishment during system circulation, achieving zero emissions and ensuring safety and environmental friendliness. Molten salt, as a heat storage medium, has a wider operating temperature range and is characterized by large-scale, long-term operation, safety, stability, and no site selection limitations. High-pressure water, as a heat storage medium, is characterized by being pollution-free and having high operating efficiency. In actual engineering projects, the specific medium used as the heat storage medium is selected based on the requirements.

[0041] In some other alternative embodiments, the heat storage medium is not limited to the three types mentioned above, but can also be liquid metal, non-metal, etc.

[0042] More specifically, in the energy storage stage, the first chamber 101 outputs a gaseous first working fluid at normal temperature and pressure. This first working fluid is compressed by the first working fluid compressor 6 and its pressure and temperature are increased to about 2 MPa / 320°C. The heat is recovered by the third heat exchanger 17, and the heat is transferred to the gaseous second working fluid by the first heat exchanger 7. The second working fluid is then liquefied by the phase change heat exchanger 8 to form a liquid at about -20°C, and finally stored in the second working fluid liquid storage tank 3. At the same time, the second working fluid liquid storage tank 3 outputs a liquid second working fluid at a low temperature of about 0.2 MPa. The second working fluid is depressurized by the expansion valve 9 to about 0.17 MPa, vaporized by the phase change heat exchanger 8, and its cooling capacity is transferred to the first working fluid by the first heat exchanger 7. The second working fluid expander 10 performs work and cools the fluid to normal pressure, and its cooling capacity is transferred to the first working fluid by the first heat exchanger 7 again. Finally, the second working fluid is stored in the second chamber 102.

[0043] During the energy release phase, the first working fluid, which is in liquid state and outputs a pressure of about 2 MPa from the first working fluid storage tank 2, is vaporized by the phase change heat exchanger 8, releases its cooling capacity by the second heat exchanger 13, is heated to about 300°C by the fourth heat exchanger 18, performs work by the first working fluid expander 14 and is depressurized to atmospheric pressure, and is finally stored in the first chamber 101. At the same time, the second working fluid, which is in gaseous state and outputs at atmospheric pressure from the second chamber 102, is cooled by the second heat exchanger 13, is pressurized to about 0.21 MPa by the second working fluid compressor 15, is cooled by the second heat exchanger 13, and is then liquefied by the phase change heat exchanger 8 to form a liquid at about -18°C, and is finally stored in the second working fluid storage tank 3.

[0044] Based on this, for a 100 MW-level energy storage system: after 6 hours of energy storage, the carbon dioxide flow rate is approximately 320 kg / s, the ammonia flow rate is approximately 69 kg / s, and the energy storage power is approximately 90 MW; after 4 hours of energy release, the carbon dioxide flow rate is approximately 480 kg / s, the ammonia flow rate is approximately 103 kg / s, and the power generation power is approximately 100 MW; the system's round-trip energy storage efficiency is approximately 74%. It can be seen that the energy storage system of this application has high efficiency and is slightly higher than the technical level of existing compressed working fluid energy storage systems. Furthermore, the highest pressure of the first working fluid in the system is approximately 2 MPa, and the highest pressure of the second working fluid is approximately 0.2 MPa. These pressures are all far lower than the pressures of existing compressed working fluid energy storage systems, indicating high reliability and safety.

[0045] As can be seen from the above technical solution, this application has the following beneficial effects:

[0046] Through the reversible gas-liquid transformation of the first and second working fluids, the system operates in synergy, freeing it from external heat or cold source conditions. Ammonia and carbon dioxide are paired, both being natural working fluids. The advantages of ammonia, such as its high latent heat of phase change, low phase change temperature, and low phase change pressure, can be utilized. This results in low ammonia consumption, low operating pressure, and low investment, while also keeping the operating pressure of carbon dioxide at a low level, which helps reduce equipment costs and improve reliability. The working fluids on both sides of the heat exchange process in the phase change heat exchanger 8 are both undergoing phase change heat exchange, resulting in a large heat transfer coefficient, which helps reduce irreversible losses and improve the system's thermal efficiency.

[0047] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0048] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0049] It should also be noted that in the apparatus, equipment, and energy storage system of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0050] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0051] It should be understood that the qualifiers “first,” “second,” “third,” “fourth,” “fifth,” and “sixth” used in the description of the embodiments of this application are only used to more clearly illustrate the technical solutions and are not intended to limit the scope of protection of this application.

[0052] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. An energy storage system, characterized in that, include: The gas storage tank (1) includes a first chamber (101) and a second chamber (102), wherein the first chamber (101) is used to store a first gaseous working fluid, and the second chamber (102) is used to store a second gaseous working fluid; First working fluid liquid storage tank (2), used to store the first working fluid in liquid form; The second working fluid liquid storage tank (3) is used to store the liquid second working fluid; The energy storage module includes an energy storage flow path (4) and a cooling flow path (5). The energy storage flow path (4) includes the outlet of the first chamber (101), the hot path of the first working fluid compressor (6), the hot path of the first heat exchanger (7), the hot path of the phase change heat exchanger (8), and the inlet of the first working fluid liquid storage tank (2) connected in series. This allows the first working fluid output from the first chamber (101) to be compressed by the first working fluid compressor (6), cooled by heat exchange through the hot path of the first heat exchanger (7), and changed from a gaseous state to a liquid state by latent heat exchange with the second working fluid in the phase change heat exchanger (8), and then transported to the first working fluid liquid storage tank (2), thereby realizing the conversion of electrical energy into pressure energy. The cooling flow path (5) includes the outlet of the second working fluid liquid storage tank (3), the expansion valve (9), the phase change heat exchanger (8), the first cold path of the first heat exchanger (7), the second working fluid expander (10), the second cold path of the first heat exchanger (7), and the inlet of the second chamber (102) connected in series. This allows the second working fluid output from the second working fluid liquid storage tank (3) to exchange latent heat with the first working fluid in the phase change heat exchanger (8) to change from liquid to gas, undergo heat exchange and temperature rise through the first cold path of the first heat exchanger (7), expand through the second working fluid expander (10), and undergo heat exchange and temperature rise through the second cold path of the first heat exchanger (7) before being input into the second chamber (102), thereby achieving the cooling of the energy storage flow path (4) by the cooling flow path (5). The energy release module includes an energy release flow path (11) and a heating flow path (12). The energy release flow path (11) includes the outlet of the first working liquid storage tank (2), the cold path of the phase change heat exchanger (8), the cold path of the second heat exchanger (13), the first working fluid expander (14), and the inlet of the first chamber (101) connected in series. This allows the first working fluid output from the first working liquid storage tank (2) to exchange latent heat with the second working fluid in the phase change heat exchanger (8) to change from liquid to gas, to exchange heat and increase temperature through the cold path of the second heat exchanger (13), to expand through the first working fluid expander (14), and to be input into the first chamber (101) to realize the conversion of pressure energy into electrical energy. The heating flow path (12) includes the outlet of the second chamber (102), the first hot path of the second heat exchanger (13), the second working fluid compressor (15), the second hot path of the second heat exchanger (13), the phase change heat exchanger (8), and the inlet of the second working fluid liquid storage tank (3) connected in series. This allows the second working fluid output from the second chamber (102) to undergo heat exchange and cooling through the first hot path of the second heat exchanger (13), compression through the second working fluid compressor (15), heat exchange and cooling through the second hot path of the second heat exchanger (13), and latent heat exchange with the first working fluid in the phase change heat exchanger (8), changing from a gaseous phase to a liquid state, and then inputting into the second working fluid liquid storage tank (3), thereby achieving the heating of the energy release flow path (11) by the heating flow path (12).

2. The energy storage system according to claim 1, characterized in that, It also includes a heat storage device (16) for recovering heat from the energy storage flow path (4) and releasing heat to the energy release flow path (11).

3. The energy storage system according to claim 2, characterized in that, The heat storage device (16) includes a third heat exchanger (17), a fourth heat exchanger (18), a cold tank (161) and a hot tank (162), and the heat storage device (16) stores a heat storage medium. The thermal path of the third heat exchanger (17) is connected in series between the thermal paths of the first working fluid compressor (6) and the first heat exchanger (7); The cold circuit of the fourth heat exchanger (18) is connected in series between the cold circuit of the first working fluid expander (14) and the second heat exchanger (13); The cold tank (161) is connected in series between the cold inlet of the third heat exchanger (17) and the hot outlet of the fourth heat exchanger (18); The hot tank (162) is connected in series between the cold outlet of the third heat exchanger (17) and the hot inlet of the fourth heat exchanger (18); During energy storage, the heat storage medium is output from the cold tank (161) and heated by heat exchange through the cold path of the third heat exchanger (17), and then enters the hot tank (162); during energy release, the heat storage medium is output from the hot tank (162) and cooled by heat exchange through the hot path of the fourth heat exchanger (18), and then enters the cold tank (161).

4. The energy storage system according to claim 1, characterized in that, The first working fluid expander (14) is used to drive the motor (19) to generate electricity, and the motor (19) is used to drive the first working fluid compressor (6) to work. The first working fluid expander (14), the motor (19) and the first working fluid compressor (6) are coaxially connected.

5. The energy storage system according to claim 1, characterized in that, The gas storage tank (1) is configured as a flexible airbag structure, the flexible airbag structure includes a first chamber (101) that can be flexibly deformed and a second chamber (102) that can be flexibly deformed.

6. The energy storage system according to any one of claims 1-5, characterized in that, The first working medium is carbon dioxide, and the second working medium is ammonia.

7. The energy storage system according to claim 3, characterized in that, The heat storage medium is heat transfer oil, molten salt, or high-pressure water.

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