Energy storage system and energy storage method

Abstract

The invention provides an energy storage system and an energy storage method, the energy storage system comprises an energy storage module, the energy storage module comprises an energy storage flow path, in the energy storage flow path, a first working medium output by a first cavity is compressed, cooled and subjected to latent heat exchange with a second working medium in a phase change heat exchanger in sequence to be converted into a liquid state from a gas state, and the liquid state is conveyed to a first working medium liquid storage tank; 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] The present application relates to the field of energy storage technology, and in particular to an energy storage system and an energy storage method. Background Art

[0002] Compressed fluid energy storage is an advanced new physical energy storage technology route. The available working fluids include air, carbon dioxide, water vapor, etc. Among them, carbon dioxide has excellent physical properties and can be combined with CCUS. It has the dual effects of energy storage and carbon dioxide sequestration. Therefore, liquefied carbon dioxide energy storage has received much attention from the industry, and technical research and development and small-scale test demonstrations have been widely carried out.

[0003] However, the process of existing liquefied carbon dioxide energy storage technology requires the use of external environmental cold source conditions to liquefy the carbon dioxide working fluid for high-density storage to reduce the cost of high-pressure storage tanks. In the energy release process, external heat source conditions are required to realize the gasification of the carbon dioxide working fluid. It is difficult for a normal plant site to simultaneously meet the above-mentioned cold source and heat source conditions. Insufficient cold source or heat source conditions will reduce the system's energy storage efficiency to <60%, which will cause major obstacles to the site selection and construction of liquefied carbon dioxide energy storage power stations. In addition, the temperature of the environmental cold source is often high, and the corresponding carbon dioxide liquefaction pressure is high (>8MPa), which sharply increases the cost of high-pressure storage tanks and reduces safety. Summary of the invention

[0004] In view of this, the present application provides an energy storage system, which realizes the reciprocal phase transition by exchanging phase change latent heat between the first working fluid and the second working fluid in the reciprocal gas-liquid transition process, so that the liquefaction process does not need to set up an external cold source, and the gasification process does not need to set up an external heat source, thereby freeing the energy storage system from the limitations of external cold source or heat source conditions. In addition, the present application also provides an energy storage method, which is applicable to the above-mentioned energy storage system.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] An energy storage system, comprising:

[0007] A gas storage reservoir, comprising a first chamber and a second chamber, wherein the first chamber is used to store a first gaseous working medium, and the second chamber is used to store a second gaseous working medium;

[0008] A first working fluid liquid storage tank, used for storing the first working fluid in liquid form;

[0009] A second working fluid liquid storage tank, used for storing the second working fluid in liquid form;

[0010] An energy storage module, comprising an energy storage flow path and a cooling flow path, wherein the energy storage flow path comprises an 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 an inlet of the first working fluid liquid storage tank which are sequentially connected in series, so that the first working fluid output from the first chamber is sequentially compressed by the first working fluid compressor, heat exchanged and cooled by the heat path of the first heat exchanger, and latent heat exchanged with the second working fluid in the phase change heat exchanger to be converted from gas to liquid, and then transported to the first working fluid liquid storage tank, so as to realize the conversion of electrical energy into pressure energy;

[0011] The cooling flow path includes an outlet of the second working fluid liquid storage tank, an expansion valve, the phase change heat exchanger, a first cold path of the first heat exchanger, a second working fluid expander, a second cold path of the first heat exchanger, and an inlet of the second chamber, which are sequentially connected in series, so that the second working fluid output from the second working fluid liquid storage tank sequentially undergoes latent heat exchange with the first working fluid in the phase change heat exchanger to change from liquid to gas, undergoes heat exchange and temperature increase through the first cold path of the first heat exchanger, undergoes expansion through the second working fluid expander, and undergoes heat exchange and temperature increase through the second cold path of the first heat exchanger, and then is input into the second chamber, so that the cooling flow path cools the energy storage flow path;

[0012] An energy release module comprises an energy release flow path and a heating flow path, wherein the energy release flow path comprises 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 sequentially connected in series, so that the first working fluid outputted from the first working fluid liquid storage tank sequentially undergoes latent heat exchange with the second working fluid in the phase change heat exchanger to be transformed from liquid to gas, undergoes heat exchange and temperature increase through the cold path of the second heat exchanger, is expanded through the first working fluid expander, and is input into the first chamber to realize the conversion of pressure energy into electrical energy;

[0013] The heating flow path includes the outlet of the second chamber, the first heat path of the second heat exchanger, the second working fluid compressor, the second heat path of the second heat exchanger, the phase change heat exchanger and the inlet of the second working fluid liquid storage tank which are connected in series in sequence, so that the second working fluid output from the second chamber is sequentially subjected to heat exchange and cooling through the first heat path of the second heat exchanger, compressed through the second working fluid compressor, subjected to heat exchange and cooling through the second heat path of the second heat exchanger, and subjected to latent heat exchange with the first working fluid in the phase change heat exchanger to change from gas to liquid, and is input into the second working fluid liquid storage tank, so as to realize the heating flow path heating the energy release flow path.

[0014] Optionally, the above energy storage system further includes a heat storage device, which is used to recover the heat of the energy storage flow path and release the 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 a heat storage medium is stored in the heat storage device; the hot circuit of the third heat exchanger is connected in series between the hot circuit of the first working fluid compressor and the first heat exchanger; the cold circuit of the fourth heat exchanger is connected in series between the cold circuit of the first working fluid expander and 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] Among them, when storing energy, the heat storage medium is output from the cold tank and is heated by heat exchange through the cold path of the third heat exchanger, and then enters the hot tank; when releasing energy, the heat storage medium is output from the hot tank and is cooled by heat exchange through the hot path of the fourth heat exchanger, and then enters the cold tank.

[0017] Optionally, in the above energy storage system, the first working fluid expander is used to drive a 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 reservoir is configured as a flexible airbag structure, and the flexible airbag structure includes the first chamber that can be flexibly deformed and the second chamber that can be flexibly deformed.

[0019] Optionally, in the above energy storage system, the first working fluid is carbon dioxide, and the second working fluid 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] An energy storage method, which is applied to the energy storage system as described in any one of the above items, and the energy storage method includes: during valley power, turning on the energy storage module; during peak power, turning on the energy release module.

[0022] The present application provides an energy storage system. During energy storage, the first working fluid is output from the first chamber to the energy storage flow path, and the second working fluid is output from the second working fluid liquid storage tank to the cooling flow path. The first working fluid of the energy storage flow path is successively compressed, cooled and liquefied before being input into the first working fluid liquid storage tank, and the second working fluid of the cooling flow path is successively gasified, heated, expanded and heated again before being input into the second chamber. The first working fluid and the second working fluid exchange latent heat in the phase change heat exchanger to realize the liquefaction of the first working fluid and the gasification of the second working fluid; the first working fluid and the second working fluid exchange heat in the first heat exchanger to realize the cooling of the first working fluid and the heating of the second working fluid. It can be seen that the first working fluid and the second working fluid exchange phase change latent heat in the phase change heat exchanger to realize phase transition, thus avoiding the setting of an external cold source when the first working fluid is liquefied. In addition, the gasified second working fluid during energy storage is also used to cool the first working fluid, making full use of the cold capacity inside the energy storage system and realizing full utilization of energy.

[0023] When releasing energy, 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 successively gasified, heated, expanded, and generated electricity before being input into the first chamber, and the second working fluid in the heating flow path is successively cooled, compressed, cooled again, and liquefied before being input into the second working fluid liquid storage tank. The first working fluid and the second working fluid exchange latent heat in the phase change heat exchanger to achieve gasification of the first working fluid and liquefaction of the second working fluid; the first working fluid and the second working fluid exchange heat in the second heat exchanger to achieve heating of the first working fluid and cooling of the second working fluid. It can be seen that the first working fluid and the second working fluid exchange phase change latent heat in the phase change heat exchanger to achieve phase transition, thus avoiding the setting of an external heat source when the first working fluid is gasified. In addition, when releasing energy, the second working fluid is also used to heat the first working fluid, making full use of the heat inside the energy storage system and achieving full energy utilization.

[0024] In summary, the first working fluid and the second working fluid exchange phase change latent heat in the reciprocal gas-liquid transformation process to achieve a reciprocal phase transition, so 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, thereby freeing the energy storage system from the limitations of external cold source or heat source conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0026] Figure 1 A schematic diagram of an energy storage system provided in an embodiment of the present application.

[0027] exist Figure 1 middle:

[0028] 1. gas storage; 101. first chamber; 102. second chamber;

[0029] 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 DESCRIPTION

[0030] The present application provides an energy storage system, which realizes the reciprocal phase transition by exchanging phase change latent heat between a first working fluid and a second working fluid in the reciprocal gas-liquid transition process, so that the liquefaction process does not require the provision of an external cold source, and the gasification process does not require the provision of an external heat source, thereby freeing the energy storage system from the limitations of external cold source and heat source conditions. In addition, the present application also provides an energy storage method, which is applicable to the above-mentioned energy storage system.

[0031] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0032] like Figure 1As shown, an embodiment of the present application provides an energy storage system. When storing energy, the first working fluid is output from the first chamber 101 to the energy storage path 4, and the second working fluid is output from the second working fluid liquid storage tank 3 to the cooling 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 in sequence, exchanges heat with the second working fluid for cooling through the heat path of the first heat exchanger 7, exchanges latent heat with the second working fluid through the heat path of the phase change heat exchanger 8 to change from gas to liquid and is 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 reduced in pressure through the expansion valve 9 in sequence, exchanges latent heat with the first working fluid in the phase change heat exchanger 8 to change from liquid to gas, exchanges heat with the second working fluid for heating through the first cold path of the first heat exchanger 7, expands through the second working fluid expander 10, exchanges heat with the first working fluid again for heating through the second cold path of the first heat exchanger 7 and is 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 gas to liquid, and the second working fluid changes from liquid to gas, and in the first heat exchanger 7 the second working fluid absorbs the heat of the first working fluid to cool the first working fluid.

[0033] When releasing energy, 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 exchanges latent heat with the second working fluid through the cold circuit of the phase change heat exchanger 8 to change from liquid to gas, exchanges heat with the second working fluid through the cold circuit of the second heat exchanger 13 to increase temperature, expands and generates electricity through the first working fluid expander 14 and is input into the first chamber 101 to convert pressure energy into electrical energy. At the same time, the second working fluid is output from the second chamber 102 and sequentially exchanges heat with the first working fluid in the first heat circuit of the second heat exchanger 13 to reduce temperature, is compressed through the second working fluid compressor 15, exchanges heat with the first working fluid in the second heat circuit of the second heat exchanger 13 to reduce temperature, exchanges latent heat with the first working fluid in the phase change heat exchanger 8 to change from gas to liquid 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 liquid to gas, the second working fluid changes from gas to liquid, and in the second heat exchanger 13 the second working fluid releases heat to the first working fluid to heat the first working fluid.

[0034] In summary, it can be seen that the first working fluid and the second working fluid exchange phase change latent heat in the reciprocal gas-liquid transformation process to achieve a reciprocal phase transition, thereby avoiding the setting of an external cold source when the first working fluid is liquefied, and the setting of an external heat source when the first working fluid is vaporized, so that the energy storage system is freed from the limitations of external cold source and heat source conditions. In addition, the second working fluid is also used to cool the first working fluid during energy storage, and the second working fluid is also used to heat the first working fluid during energy release, making full use of the cold and heat inside the energy storage system to achieve full utilization of energy.

[0035] In addition, the energy storage system further includes a heat storage device 16, which is used to recover the heat of the energy storage flow path 4 and release the heat to the energy release flow path 11. It can be understood that when storing energy, the heat storage device 16 absorbs the heat of the first working fluid and stores the heat; when releasing energy, the previously stored heat is released to the first working fluid, thereby achieving full utilization of the heat of the energy storage system and improving the energy storage efficiency.

[0036] 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 a heat storage medium is stored in the heat storage device 16; the heat circuit of the third heat exchanger 17 is connected in series between the heat circuit 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 circuit inlet of the third heat exchanger 17 and the hot circuit outlet of the fourth heat exchanger 18; the hot tank 162 is connected in series between the cold circuit outlet of the third heat exchanger 17 and the hot circuit inlet of the fourth heat exchanger 18; wherein, when storing energy, the heat storage medium is output from the cold tank 161 and is heated by heat exchange through the cold circuit of the third heat exchanger 17, and then enters the hot tank 162; when releasing energy, the heat storage medium is output from the hot tank 162 and is cooled by heat exchange through the hot circuit of the fourth heat exchanger 18, and then enters the cold tank 161. It can be seen that the composition of the heat storage device 16 is simple, and the heat storage principle is simple and reliable.

[0037] 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 to work, and 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 mode of the expander and the compressor is realized, which reduces the intermediate links, reduces the loss of intermediate transmission energy, improves efficiency, and also saves installation space, making the entire device more compact.

[0038] In some optional embodiments, the gas storage reservoir 1 is configured as a flexible airbag structure, and the flexible airbag structure includes a first chamber 101 that can be flexibly deformed and a second chamber 102 that can be flexibly deformed. From the above, it can be seen that during energy storage, the first working fluid is output from the first chamber 101, and the second working fluid is input into the second chamber 102. During the energy release stage, the first working fluid is input into the first chamber 101, and the second working fluid is output from the second chamber 102. It can be seen that the two working fluids enter and exit one by one, so that the space of the gas storage reservoir 1 is always effectively utilized, and there is no need to increase the investment and floor space of a new gas storage reservoir 1.

[0039] In some other optional embodiments, the gas storage reservoir 1 can be configured as a rigid structure, and the rigid structure is internally divided into two groups of flexibly deformable chambers by a flexibly deformable airbag structure.

[0040] In some optional embodiments, the first working fluid is carbon dioxide and the second working fluid is ammonia. The latent heat exchange between carbon dioxide and ammonia is an efficient way of utilizing energy, which can realize the effective conversion and utilization of energy in the process of phase change of substances.

[0041] In some optional embodiments, the heat storage medium is thermal oil, molten salt or high-pressure water. When thermal oil is used as the heat storage medium, there is no fuel replenishment during the system circulation process, which achieves zero emissions, safety and environmental protection; molten salt is used as the heat storage medium, and its operating temperature range is wider, and molten salt heat storage has the characteristics of large-scale, long-term, safe and stable, and not restricted by site selection; high-pressure water is used as the heat storage medium, which has the characteristics of no pollution and high operating efficiency. In actual engineering, the specific medium used as the heat storage medium is selected according to demand.

[0042] In some other optional embodiments, the heat storage medium is not limited to the above three types, and may also be liquid metal, non-metal, etc.

[0043] In addition, the present application proposes an energy storage method, which is applicable to the above-mentioned energy storage system. The energy storage method includes: turning on the energy storage module during valley electricity season; turning on the energy release module during peak electricity season. In this way, the difference between peak and valley electricity prices is fully utilized to achieve maximum energy storage benefits.

[0044] More specifically, in the energy storage stage, the first chamber 101 outputs a gaseous first working fluid at room temperature and pressure, which is compressed by the first working fluid compressor 6 and then pressurized and heated to about 2MPa / 320°C, and heat is recovered by the third heat exchanger 17. The heat is transferred to the gaseous second working fluid through the first heat exchanger 7, and then liquefied by the phase change heat exchanger 8 to form a liquid at about -20°C, and finally input into the second working fluid liquid storage tank 3 for storage; at the same time, the second working fluid liquid storage tank 3 outputs a liquid second working fluid with a low-temperature pressure of about 0.2MPa, and the second working fluid is successively reduced in pressure by the expansion valve 9 to about 0.17MPa, vaporized by the phase change heat exchanger 8, and the cold is transferred to the first working fluid through the first heat exchanger 7. The second working fluid expander 10 does work and reduces the temperature to normal pressure, and then transfers the cold to the first working fluid through the first heat exchanger 7, and finally input into the second chamber 102 for storage.

[0045] In the energy release stage, the liquid first working fluid with a pressure of about 2 MPa output by the first working fluid liquid storage tank 2 is successively vaporized through the phase change heat exchanger 8, releases cold energy through the second heat exchanger 13, is heated to about 300°C through the fourth heat exchanger 18, works through the first working fluid expander 14 and is reduced in pressure to normal pressure, and is finally input into the first chamber 101 for storage; at the same time, the normal-pressure gaseous second working fluid output by the second chamber 102 is successively cooled through the second heat exchanger 13, is pressurized to about 0.21 MPa through the second working fluid compressor 15, is cooled through the second heat exchanger 13, and is liquefied through the phase change heat exchanger 8 to form a liquid at about -18°C, and is finally input into the second working fluid liquid storage tank 3 for storage.

[0046] According to the above method, for a 100-megawatt energy storage system: energy storage for 6 hours, carbon dioxide flow rate is about 320kg / s, ammonia flow rate is about 69kg / s, and energy storage power is about 90MW; energy release for 4 hours, carbon dioxide flow rate is about 480kg / s, ammonia flow rate is about 103kg / s, and power generation power is about 100MW; the system energy storage round-trip efficiency is about 74%; it can be seen that the energy storage system of the present application is highly efficient and slightly higher than the technical level of existing compressed working fluid energy storage systems, and the maximum pressure of the first working fluid of the system is about 2MPa, and the maximum pressure of the second working fluid is about 0.2MPa. The above pressures are much lower than the pressures of existing compressed working fluid energy storage systems, and have high reliability and safety.

[0047] It can be seen from the above technical solution that the present application has the following beneficial effects:

[0048] Through the reciprocal gas-liquid conversion of the first working fluid and the second working fluid, the coordinated operation can free the system operation from external heat source or cold source conditions; ammonia and carbon dioxide are selected to be paired, both of which are natural working fluids, and the advantages of ammonia's large low-temperature gas-liquid phase change latent heat, low phase change temperature, and low phase change pressure can be utilized, with small ammonia consumption, low working pressure, and low investment, and the working pressure of carbon dioxide is also at a low level, which is beneficial to reducing equipment costs and improving reliability; the working fluids on both sides of the heat exchange process of the phase change heat exchanger 8 are phase change heat, and the heat transfer coefficient is large, which is beneficial to reducing irreversible losses and improving the thermal efficiency of the system.

[0049] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, not for limitation, and the above details do not limit the present application to being implemented by adopting the above specific details.

[0050] The block diagrams of the devices, apparatuses, equipment, and systems involved in this application are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, apparatuses, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0051] It should also be noted that in the device, equipment and energy storage system of the present application, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as an equivalent solution of the present application.

[0052] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0053] It should be understood that the qualifiers "first", "second", "third", "fourth", "fifth" and "sixth" used in the description of the embodiments of the present application are only used to more clearly explain the technical solutions and cannot be used to limit the scope of protection of the present application.

[0054] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. An energy storage system, characterized in that: include: A gas storage reservoir (1) comprises a first chamber (101) and a second chamber (102), wherein the first chamber (101) is used to store a first working medium in a gaseous state, and the second chamber (102) is used to store a second working medium in a gaseous state; A first working fluid liquid storage tank (2), used for storing the first working fluid in liquid form; A second working fluid liquid storage tank (3), used for storing the second working fluid in liquid form; An energy storage module comprises an energy storage flow path (4) and a cooling flow path (5), wherein the energy storage flow path (4) comprises an outlet of the first chamber (101), a first working fluid compressor (6), a heat path of a first heat exchanger (7), a heat path of a phase change heat exchanger (8) and an inlet of the first working fluid liquid storage tank (2) which are sequentially connected in series, so that the first working fluid output from the first chamber (101) is sequentially compressed by the first working fluid compressor (6), heat exchanged and cooled by the heat path of the first heat exchanger (7), and latent heat exchanged with the second working fluid in the phase change heat exchanger (8) to be converted from gaseous state to liquid state, 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) comprises an outlet of the second working fluid liquid storage tank (3), an expansion valve (9), the phase change heat exchanger (8), a first cold path of the first heat exchanger (7), a second working fluid expander (10), a second cold path of the first heat exchanger (7) and an inlet of the second chamber (102) which are sequentially connected in series, so that the second working fluid output from the second working fluid liquid storage tank (3) sequentially undergoes latent heat exchange with the first working fluid in the phase change heat exchanger (8) to change from liquid to gas, undergoes heat exchange and temperature increase through the first cold path of the first heat exchanger (7), undergoes expansion through the second working fluid expander (10), undergoes heat exchange and temperature increase through the second cold path of the first heat exchanger (7), and is then input into the second chamber (102), thereby achieving cooling of the energy storage flow path (4) by the cooling flow path (5); An energy release module comprises an energy release flow path (11) and a heating flow path (12), wherein the energy release flow path (11) comprises the outlet of the first working fluid 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) which are sequentially connected in series, so that the first working fluid output from the first working fluid liquid storage tank (2) sequentially undergoes latent heat exchange with the second working fluid in the phase change heat exchanger (8) to be transformed from liquid to gas, undergoes heat exchange and temperature increase in the cold path of the second heat exchanger (13), is expanded in the first working fluid expander (14), and is input into the first chamber (101) to realize the conversion of pressure energy into electrical energy; The heating flow path (12) comprises an outlet of the second chamber (102), a first heat path of the second heat exchanger (13), a second working fluid compressor (15), a second heat path of the second heat exchanger (13), the phase change heat exchanger (8) and an inlet of the second working fluid liquid storage tank (3) which are sequentially connected in series, so that the second working fluid output from the second chamber (102) is sequentially subjected to heat exchange and cooling through the first heat path of the second heat exchanger (13), compressed through the second working fluid compressor (15), subjected to heat exchange and cooling through the second heat path of the second heat exchanger (13), and subjected to latent heat exchange with the first working fluid in the phase change heat exchanger (8) to change from gaseous state to liquid state, and then fed into the second working fluid liquid storage tank (3), so as to achieve 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), wherein the heat storage device (16) is used to recover the heat of the energy storage flow path (4) and release the 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) comprises a third heat exchanger (17), a fourth heat exchanger (18), a cold tank (161) and a hot tank (162), and a heat storage medium is stored in the heat storage device (16); The heat path of the third heat exchanger (17) is connected in series between the heat 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 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); When storing energy, the heat storage medium is output from the cold tank (161) and is heated up by heat exchange through the cold path of the third heat exchanger (17), and then enters the hot tank (162); when releasing energy, the heat storage medium is output from the hot tank (162) and is cooled down 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 a motor (19) to generate electricity, and the motor (19) is used to drive the first working fluid compressor (6) to operate. 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 reservoir (1) is configured as a flexible airbag structure, wherein the flexible airbag structure comprises the first chamber (101) capable of flexibly deforming and the second chamber (102) capable of flexibly deforming.

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

8. An energy storage method, characterized in that: The energy storage system according to any one of claims 1 to 7 is applied, wherein the energy storage method comprises: turning on the energy storage module during valley power consumption; and turning on the energy release module during peak power consumption.

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