A Seasonal Compressed Air Energy Storage System and Method

Abstract

The present invention discloses a seasonal compressed air energy storage system, comprising a compressor unit, a power mechanism, a turbine unit, a heat exchange mechanism, and an underground water-bearing or saline layer. The compressor unit and the power mechanism are detachably connected, and the power mechanism and the turbine unit are detachably connected. The underground water-bearing or saline layer is covered with a dense cover layer, and the underground water-bearing or saline layer is connected to a group of working wells extending to the ground. An air inlet pipe is provided between the compressor unit and the group of working wells, and an air inlet valve is provided on the air inlet pipe. An air outlet pipe is provided between the turbine unit and the group of working wells, and an air outlet valve is provided on the air outlet pipe. Both the air inlet pipe and the air outlet pipe are passed through the heat exchange mechanism. Also disclosed is a seasonal compressed air energy storage method, comprising the steps of: injecting buffer gas; energy storage; and energy release. This seasonal compressed air energy storage system and method have a large energy storage scale, a long storage period, low development cost, a small footprint, low environmental impact, high energy efficiency, and can be deployed across seasons.

Description

Technical Field

[0001] The present invention relates to the field of energy storage technology, and in particular to a seasonal compressed air energy storage system and method. Background Art

[0002] Over the past century, industrialization has led to massive greenhouse gas emissions, contributing to global warming and sea level rise. Studies have shown that the Earth's average surface temperature is currently approximately 1.2°C higher than before the Industrial Revolution. To achieve the goal of limiting global average temperature rise to no more than 2°C above pre-industrial levels by the end of the 21st century, and striving to keep it within 1.5°C, the vigorous development of renewable energy, represented by wind and solar power, is inevitable. However, due to the inherent limitations of renewable energy, such as volatility and intermittency, the capacity for renewable energy generation and consumption, as well as the proportion of renewable energy in applied applications, is relatively low. Large-scale energy storage technology is a key means of increasing the utilization of renewable energy. Currently, only pumped hydropower storage and compressed air energy storage are suitable for large-scale, long-term power storage exceeding 100MW.

[0003] To achieve large-scale utilization of renewable energy and seasonal changes in electricity demand, it is necessary to store electricity across seasons. However, pumped storage technology requires abundant water resources and suitable geographical conditions, which are often difficult to meet in areas rich in renewable energy. Traditional compressed air energy storage typically uses underground gas storage facilities such as salt caverns, abandoned mines, and rock caverns for energy storage. To meet seasonal electricity storage requirements, the gas storage facilities need to store more than hundreds of millions of cubic meters of air. The huge gas storage capacity results in high construction costs. In addition, the compression heat during the compression process of traditional air energy storage systems is not recycled, and the expansion process relies on the combustion of fossil fuels such as natural gas, resulting in low system energy efficiency.

[0004] Therefore, how to provide a compressed air energy storage method that is suitable for seasonal large-scale energy storage, has low development costs and high system energy efficiency is a difficult problem that needs to be solved urgently. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide a seasonal compressed air energy storage system and method with large energy storage scale, long storage cycle, low development cost, small footprint, small impact on the environment, high energy efficiency and the ability to achieve cross-seasonal energy allocation.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A seasonal compressed air energy storage system includes a ground power station part and an underground storage part, wherein the ground power station part includes a compressor unit, a power mechanism, a turbine unit and a heat exchange mechanism, and the underground storage part includes an underground water-bearing or saline water layer, a dense cover layer, an overlying rock layer, an underlying rock layer, a working well group, and a monitoring well; the compressor unit and the power mechanism are detachably connected via a first linkage mechanism, and the turbine unit and the power mechanism are detachably connected via a second linkage mechanism, the dense cover layer is covered on the underground water-bearing or saline water layer, the underlying rock layer is located below the underground water-bearing or saline water layer, the underground water-bearing or saline water layer is connected to a working well group extending to the ground, an air intake pipe is connected between the compressor unit and the working well group, an air intake valve is provided on the air intake pipe, an air outlet pipe is connected between the turbine unit and the working well group, an air outlet valve is provided on the air outlet pipe, and both the air intake pipe and the air outlet pipe are passed through the heat exchange mechanism.

[0008] As a further improvement of the above technical solution:

[0009] The working well group includes multiple working wells, each of which is arranged at intervals of 20m to 150m. The two ends of the working wells extend to the ground and the bottom of the underground water-bearing or saline layer respectively. The well wall portion of each working well located in the underground water-bearing or saline layer section is arranged with perforations.

[0010] The underground aquifer or saline layer is also connected to a plurality of monitoring wells, which are arranged around the periphery of the working well group. The two ends of the monitoring wells extend to the ground and the bottom of the underground aquifer or saline layer respectively. The well wall portion of each monitoring well located in the underground aquifer or saline layer section is perforated.

[0011] The monitoring wells are kept at a distance of 30m-80m from the working well group.

[0012] The underground aquifer or saline water layer is buried at a depth of 20m to 150m underground, the thickness of the underground aquifer or saline water layer is 50m to 150m, the permeability is higher than 0.1 Darcy, and the porosity is greater than 0.1.

[0013] The capillary breakthrough pressure of the dense cap layer is more than 1.5 times the hydrostatic pressure of the formation at the same depth, the thickness is more than 10m, and its permeability is lower than the permeability of the underground water-bearing or saline water layer.

[0014] The compressor unit includes a low-pressure compressor, a medium-pressure compressor and a high-pressure compressor. The air intake pipeline includes a first pipeline, a second pipeline and a third pipeline. The air inlet of the low-pressure compressor is connected to the air source, and the air outlet is connected to the air inlet of the medium-pressure compressor through the first pipeline. The air outlet of the medium-pressure compressor is connected to the air inlet of the high-pressure compressor through the second pipeline. The air outlet of the high-pressure compressor is connected to the working well group through the third pipeline. The air intake valve is provided on the third pipeline. The first pipeline, the second pipeline and the third pipeline are all provided in the heat exchange mechanism.

[0015] The turbine unit includes a high-pressure turbine and a low-pressure turbine, and the outlet pipe includes a fourth pipe and a fifth pipe. The air inlet of the high-pressure turbine is connected to the working well group through the fourth pipe, and the air outlet is connected to the air inlet of the low-pressure turbine through the fifth pipe. The air outlet of the low-pressure turbine is connected to the atmosphere. The fourth pipe and the fifth pipe are both arranged in the heat exchange mechanism.

[0016] The heat exchange mechanism includes a heat storage tank, a cold storage tank, a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a fifth heat exchanger, and a sixth heat exchanger. The first heat exchanger, the second heat exchanger, and the third heat exchanger are connected in parallel between the inlet of the heat storage tank and the outlet of the cold storage tank. The fourth heat exchanger and the fifth heat exchanger are connected in parallel between the outlet of the heat storage tank and the inlet of the cold storage tank. The sixth heat exchanger is connected to the air outlet end of the low-pressure turbine and is connected to the inlet of the heat storage tank. The first pipe is arranged in the first heat exchanger, the second pipe is arranged in the second heat exchanger, the third pipe is arranged in the third heat exchanger, the fourth pipe is arranged in the fourth heat exchanger, and the fifth pipe is arranged in the fifth heat exchanger.

[0017] A seasonal compressed air energy storage method, using the above seasonal compressed air energy storage system, mainly includes the following steps:

[0018] S1. Buffer gas injection: Open the air inlet valve, close the air outlet valve, start the power mechanism to drive the compressor unit to operate, inject a predetermined amount of buffer gas into the underground water-bearing or saline water layer through the working well group to form an initial air bag, and then close the air inlet valve;

[0019] S2. Energy storage: During the off-peak season, the second linkage mechanism is disconnected, the first linkage mechanism is connected, the air inlet valve is opened, and the air outlet valve is closed. The power mechanism is started to drive the compressor unit to operate, and a predetermined amount of energy storage gas is injected into the underground water-bearing or saline aquifer through the working well group. The air inlet valve is then closed to achieve electrical energy storage.

[0020] S3. Energy release: During the peak electricity consumption season, the second linkage mechanism is connected, the first linkage mechanism is disconnected, the air inlet valve is closed, and the air outlet valve is opened. The air in the underground water-bearing or saline water layer is discharged through the working well group, driving the turbine unit to operate. The turbine unit drives the power mechanism to operate to supply power to users, thereby realizing energy release.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] This seasonal compressed air energy storage system, on the one hand, uses underground aquifers or saline water layers as seasonal energy storage underground gas storage, which has a large energy storage scale and a long storage period. Compared with artificial storage tanks, salt caverns, abandoned mines and tunnels, and hard rock caverns, the development cost is low, making it easier to economically store hundreds of millions of cubic meters of air. In addition, using underground aquifers or saline water layers as seasonal energy storage underground gas storage takes up a small area and has a small impact on the environment. Underground aquifers or saline water layers are widely distributed and are easier to obtain geologically (such formation conditions can also be found near areas rich in renewable energy). On the other hand, this seasonal compressed air energy storage system uses a heat exchange mechanism to recover the heat energy generated by the compression process of the compressor unit and the waste heat of the exhaust gas emitted by the turbine unit. During the energy release phase, the expansion process of the turbine unit does not require fossil fuel re-firing, which greatly improves the energy efficiency of the system. Thirdly, this seasonal compressed air energy storage system and method can achieve large-scale storage and cross-seasonal allocation of electricity, smooth out long-term power fluctuations, meet large-scale and long-term electricity demand, and achieve true "peak shaving and valley filling".

[0023] This seasonal compressed air energy storage method, on the one hand, uses underground aquifers or saline water layers as seasonal energy storage underground gas storage, which has a large energy storage scale and a long storage period. Compared with artificial storage tanks, salt caverns, abandoned mines and tunnels, and hard rock caverns, the development cost is low, making it easier to economically store hundreds of millions of cubic meters of air. Furthermore, using underground aquifers or saline water layers as seasonal energy storage underground gas storage takes up a small area and has a small impact on the environment. Underground aquifers or saline water layers are widely distributed and are easier to obtain geologically (such formations can also be found near areas rich in renewable energy). On the other hand, this seasonal compressed air energy storage system uses a heat exchange mechanism to recover the heat energy generated by the compression process of the compressor unit and the waste heat of the exhaust gas emitted by the turbine unit. During the energy release phase, the expansion process of the turbine unit does not require fossil fuel supplementary combustion, which greatly improves the energy efficiency of the system. Thirdly, this seasonal compressed air energy storage system and method can achieve large-scale storage and cross-seasonal allocation of electricity, smoothing out long-term power fluctuations and meeting large-scale and long-term electricity demand, achieving true "peak shaving and valley filling". BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a structural schematic diagram of the seasonal compressed air energy storage system of the present invention.

[0025] Figure 2 It is a plan layout diagram of the working well group and monitoring wells of the seasonal compressed air energy storage system of the present invention.

[0026] The numbers in the figure represent:

[0027] 1. Low-pressure compressor; 2. First heat exchanger; 3. Medium-pressure compressor; 4. Second heat exchanger; 5. High-pressure compressor; 6. Third heat exchanger; 7. Heat storage tank; 8. First linkage mechanism; 9. Power mechanism; 10. Second linkage mechanism; 11. Cold storage tank; 12. Fourth heat exchanger; 13. High-pressure turbine; 14. Fifth heat exchanger; 15. Low-pressure turbine; 16. Inlet pipe; 161. First pipe; 162. Second pipe; 163. Third pipe; 17. Inlet valve; 18. Outlet valve; 19. Monitoring well; 20. Working well; 21. Outlet pipe; 211. Fourth pipe; 212. Fifth pipe; 23. Sixth heat exchanger; 24. Overburden; 25. Dense cap rock; 26. Underground aquifer or saline layer; 27. Gas-water contact surface; 28. Underburden. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0030] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature identified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0031] In the present invention, unless otherwise expressly specified or limited, terms such as "assemble," "connect," "connect," and "fix" should be understood in a broad sense. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection or electrical connection; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0032] Example 1:

[0033] Figure 1 and Figure 2 An embodiment of the seasonal compressed air energy storage system of the present invention is shown, which includes a ground power station part and an underground storage part, wherein the ground power station part includes a compressor unit, a power mechanism 9, a turbine unit and a heat exchange mechanism, and the underground storage part includes an underground water-bearing or saline layer 26, a dense cap layer 25, an overburden stratum 24, an underlying stratum 28, a working well group, and a monitoring well 19; the compressor unit and the power mechanism 9 are detachably connected through a first linkage mechanism 8, and the turbine unit and the power mechanism 9 are connected through a second linkage mechanism 1 0 is detachably connected, a dense cap layer 25 is provided on an underground water-bearing or saline layer 26, an underlying rock layer 28 is located below the underground water-bearing or saline layer 26, the underground water-bearing or saline layer 26 is connected to a working well group extending to the ground, an air intake pipe 16 is connected between the compressor unit and the working well group, an air intake valve 17 is provided on the air intake pipe 16, an air outlet pipe 21 is connected between the turbine unit and the working well group, an air outlet valve 18 is provided on the air outlet pipe 21, and both the air intake pipe 16 and the air outlet pipe 21 are provided in the heat exchange mechanism.

[0034] This seasonal compressed air energy storage system, on the one hand, uses the underground aquifer or saline layer 26 of the underground aquifer as a seasonal energy storage underground gas storage reservoir, which has a large energy storage scale and a long storage period. Compared with artificial storage tanks, salt caverns, abandoned mines and tunnels, and hard rock caverns, the development cost is low, and it is easier to achieve hundreds of millions of cubic meters of air storage in terms of economic cost; and the use of the underground aquifer or saline layer 26 of the underground aquifer as a seasonal energy storage underground gas storage reservoir has a small footprint and a small impact on the environment. The underground aquifer or saline layer 26 of the underground aquifer is widely distributed underground and is easier to obtain in terms of geological conditions (the formation conditions can also be found near renewable energy-rich areas). On the other hand, this seasonal compressed air energy storage system uses a heat exchange mechanism to recover the heat energy generated by the compression process of the compressor unit and the waste heat of the exhaust gas emitted by the turbine unit. During the energy release stage, the expansion process of the turbine unit does not require fossil fuel re-firing, which greatly improves the energy efficiency of the system. Thirdly, this seasonal compressed air energy storage system can achieve large-scale storage and cross-seasonal allocation of electricity, smooth out long-term fluctuations in electricity consumption, meet large-scale and long-term electricity demand, and achieve true "peak shaving and valley filling".

[0035] Furthermore, in this embodiment, the working well cluster includes multiple working wells 20 to expand the system's energy storage capacity. Each working well 20 is spaced at intervals of 20 to 150 meters to balance energy storage efficiency and power plant construction costs. The ends of each working well 20 extend to the surface and the bottom of the underground aquifer or saline layer 26, respectively. The portion of the wellbore of each working well 20 located in the underground aquifer or saline layer 26 is perforated. Furthermore, in this embodiment, the underground aquifer or saline layer 26 is connected to multiple monitoring wells 19, which are arranged around the periphery of the working well cluster. The ends of each monitoring well 19 extend to the surface and the bottom of the underground aquifer or saline layer 26, respectively. The portion of the wellbore of each monitoring well 19 located in the underground aquifer or saline layer 26 is perforated.

[0036] Furthermore, in this embodiment, the monitoring well 19 is spaced apart from the working well group, and the spacing is preferably 30m to 80m. The monitoring well 19 can monitor the temperature, pressure, and displacement changes of the geological body, as well as the migration and leakage of gas in the underground water-bearing or saline layer 26.

[0037] Furthermore, in this embodiment, the underground aquifer or saline layer 26 is buried at a depth of 20m to 150m, has a thickness of 50m to 150m, a permeability greater than 0.1 Darcy, and a porosity greater than 0.1. Furthermore, the site of the underground aquifer or saline layer 26 is preferably located near a renewable energy-rich area. The layer has a thickness of 50m to 150m and a porosity of 0.15 to 0.3 to ensure sufficient gas storage space, and a permeability of 0.1 to 1.33 Darcy to ensure gas injectability and diffusivity.

[0038] Furthermore, in this embodiment, the capillary breakthrough pressure of the dense cap layer 25 is greater than 1.5 times the hydrostatic pressure of the formation at the same depth, the thickness is greater than 10 meters, and its permeability is lower than the permeability of the underground aquifer or saline layer 26. The dense cap layer 25 is free of geological defects such as faults, thereby confining air to the underground aquifer or saline layer 26 as much as possible to prevent air leakage.

[0039] Furthermore, in this embodiment, the compressor unit includes a low-pressure compressor 1, an intermediate-pressure compressor 3, and a high-pressure compressor 5. The air intake pipe 16 includes a first pipe 161, a second pipe 162, and a third pipe 163. The air intake of the low-pressure compressor 1 is connected to the air source, and the air outlet is connected to the air intake of the intermediate-pressure compressor 3 via the first pipe 161. The air outlet of the intermediate-pressure compressor 3 is connected to the air intake of the high-pressure compressor 5 via the second pipe 162. The air outlet of the high-pressure compressor 5 is connected to the working well group via the third pipe 163. The air intake valve 17 is provided on the third pipe 163. The first pipe 161, the second pipe 162, and the third pipe 163 are all provided in the heat exchange mechanism. The power of the high-pressure compressor 5 is greater than that of the intermediate-pressure compressor 3, and the power of the intermediate-pressure compressor 3 is greater than that of the low-pressure compressor 1.

[0040] Furthermore, in this embodiment, the turbine assembly includes a high-pressure turbine 13 and a low-pressure turbine 15. The outlet conduit 21 includes a fourth conduit 211 and a fifth conduit 212. The air inlet of the high-pressure turbine 13 is connected to the working well group via the fourth conduit 211, and the air outlet is connected to the low-pressure turbine 15 via the fifth conduit 212. The air outlet of the low-pressure turbine 15 is open to the atmosphere. Both the fourth conduit 211 and the fifth conduit 212 are disposed within the heat exchange mechanism. The power of the high-pressure turbine 13 is greater than that of the low-pressure turbine 15.

[0041] Furthermore, in this embodiment, the heat exchange mechanism includes a heat storage tank 7, a cold storage tank 11, a first heat exchanger 2, a second heat exchanger 4, a third heat exchanger 6, a fourth heat exchanger 12, a fifth heat exchanger 14 and a sixth heat exchanger 23. The first heat exchanger 2, the second heat exchanger 4 and the third heat exchanger 6 are connected in parallel between the inlet of the heat storage tank 7 and the outlet of the cold storage tank 11. The fourth heat exchanger 12 and the fifth heat exchanger 14 are connected in parallel between the outlet of the heat storage tank 7 and the inlet of the cold storage tank 11. The sixth heat exchanger 23 is connected to the outlet end of the low-pressure turbine 15 and to the inlet end of the heat storage tank 7. The first pipe 161 is arranged in the first heat exchanger 2, the second pipe 162 is arranged in the second heat exchanger 4, the third pipe 163 is arranged in the third heat exchanger 6, the fourth pipe 211 is arranged in the fourth heat exchanger 12, and the fifth pipe 212 is arranged in the fifth heat exchanger 14.

[0042] Furthermore, in this embodiment, the first heat exchanger 2, the second heat exchanger 4, and the third heat exchanger 6 use the heat exchange medium in the cold storage tank 11 to recover the heat generated by the air during the compression process at each stage. The sixth heat exchanger 23 is used to recover the waste heat of the power generation air. The heat recovered by the above-mentioned heat exchangers through the heat exchange medium is transported to the heat storage tank 7 for storage; the fourth heat exchanger 12 and the fifth heat exchanger 14 replenish heat for the air released from the underground aquifer or saline layer 26 during the energy release and power generation stage by transporting heat energy from the heat storage tank 7, and transport the cooled heat exchange medium after replenishment to the cold storage tank 11 for storage.

[0043] Furthermore, the power mechanism 9 is coaxially arranged with the compressor unit and the turbine unit via a first linkage mechanism 8 and a second linkage mechanism 10, respectively. Specifically, the low-pressure compressor 1, the intermediate-pressure compressor 3, the high-pressure compressor 5, and the first linkage mechanism 8 are coaxially connected to the power mechanism 9, while the high-pressure turbine 13, the low-pressure turbine 15, and the second linkage mechanism 10 are coaxially connected to the power mechanism 9. Furthermore, the low-pressure compressor 1, the intermediate-pressure compressor 3, and the high-pressure compressor 5 are coaxially connected, and the high-pressure turbine 13 and the low-pressure turbine 15 are coaxially connected. The overall structure is compact, the functions of the various components are clearly divided, and the space occupied is small, which can save construction costs.

[0044] Furthermore, the first linkage mechanism 8 and the second linkage mechanism 10 are both electrically controlled clutches (ie, controlled disconnection and connection).

[0045] During the off-peak period of electricity consumption, air is injected to store energy. That is, the surplus electricity from renewable energy sources such as peak-valley electricity, abandoned wind power, abandoned photovoltaic power, and hydropower is used to drive the power mechanism 9 (motor) to drive the compressor unit to rotate. The air is pressurized step by step through the low-pressure compressor 1, the medium-pressure compressor 3 and the high-pressure compressor 5, and heat is exchanged through the first heat exchanger 2, the second heat exchanger 4, and the third heat exchanger 6 in turn (making the compression process at each stage close to isothermal compression). After the pressure is adjusted by the intake valve 17 (throttle valve), the air is injected into the underground water-bearing or saline water layer 26 through the working well group, thereby realizing large-scale and long-term storage of electricity.

[0046] During peak electricity consumption periods, air extraction is carried out to release energy. The high-pressure air stored in the underground water-bearing or saline layer 26 is discharged through the working well group, and after pressure regulation by the outlet valve 18 (throttle valve), it passes through the fourth heat exchanger 12, absorbs heat and heats up, and then enters the high-pressure turbine 13 to expand and perform work. After the work is completed, the air absorbs heat and heats up again in the fifth heat exchanger 14, and then enters the low-pressure turbine 15 to expand and perform work. The turbine unit drives the power mechanism 9 (generator) to generate electricity. After the work is completed, the air recovers the waste heat through the sixth heat exchanger 23 and can be discharged into the atmosphere, realizing energy release. The electricity generated by the power mechanism 9 (generator) is continuously transmitted to the electricity demand area through the transmission line, realizing energy transfer.

[0047] Furthermore, before the air is injected into the energy storage, a sufficient amount of buffer gas needs to be injected into the underground water or salt water 26 to form an initial air bag to provide pressure support for the subsequent extraction and energy release process and prevent groundwater from flowing into the working wellbore. The buffer gas can be air or carbon dioxide, and the buffer gas injection method adopts intermittent injection. The total amount of injected buffer gas is between 10 and 100 times the total amount of energy storage working fluid air injected.

[0048] Example 2:

[0049] A seasonal compressed air energy storage method, using the seasonal compressed air energy storage system, mainly comprises the following steps:

[0050] S1. Buffer gas injection: Open the air inlet valve 17, close the air outlet valve 18, start the power mechanism 9 to drive the compressor unit to operate, inject a predetermined amount of buffer gas into the underground water-bearing or saline layer 26 through the working well group to form an initial air bag, and then close the air inlet valve 17;

[0051] S2. Energy storage: During the off-peak season, the second linkage mechanism 10 is disconnected, the first linkage mechanism 8 is connected, the air inlet valve 17 is opened, and the air outlet valve 18 is closed. Electric energy drives the power mechanism 9 (motor) to operate, thereby driving the compressor unit. A predetermined amount of energy storage gas is injected into the underground aquifer or saline layer 26 through the working well group. The air inlet valve 17 is then closed to achieve electrical energy storage.

[0052] S3. Energy release: During peak electricity consumption season, the second linkage mechanism 10 is connected, the first linkage mechanism 8 is disconnected, the air inlet valve 17 is closed, and the air outlet valve 18 is opened. The air in the underground aquifer or saline layer 26 is discharged through the working well group, causing the turbine unit to operate. The turbine unit drives the power mechanism 9 (generator) to operate to supply power to users, thereby achieving energy release.

[0053] Furthermore, the buffer gas may be air, carbon dioxide, etc., and the buffer gas injection method adopts intermittent injection, and the total amount of injected buffer gas is between 10 and 100 times the total amount of energy storage working fluid air injected.

[0054] Furthermore, the energy storage-release cycle mode is a seasonal cycle operation mode, with a cycle of 12 months. The energy storage time is 2 to 6 months, and the energy release time is 2 to 4 months. There is a static storage period of 2 to 3 months in between. In this way, large-scale storage of electricity and cross-seasonal allocation of energy can be achieved, meeting large-scale and long-term electricity demand, and achieving the smoothing of seasonal fluctuations in the power grid and true "peak shaving and valley filling".

[0055] Although the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, utilize the technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes. Therefore, any simple modification, equivalent change, and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection of the technical solution of the present invention.

Claims

1. A seasonal compressed air energy storage system, characterized by: The invention comprises a ground power station part and an underground storage part, wherein the ground power station part comprises a compressor unit, a power mechanism (9), a turbine unit and a heat exchange mechanism, and the underground storage part comprises an underground water-bearing or saline layer (26), a dense cover layer (25), an overburden layer (24), an underlying rock layer (28), a working well group, and a monitoring well (19); the compressor unit and the power mechanism (9) are detachably connected via a first linkage mechanism (8), the turbine unit and the power mechanism (9) are detachably connected via a second linkage mechanism (10), and the dense cover layer (25) is arranged underground. On the aquifer or saline layer (26), the underlying rock layer (28) is located below the underground aquifer or saline layer (26), the underground aquifer or saline layer (26) is connected to a working well group extending to the ground, an air intake pipe (16) is connected between the compressor unit and the working well group, an air intake valve (17) is provided on the air intake pipe (16), an air outlet pipe (21) is connected between the turbine unit and the working well group, an air outlet valve (18) is provided on the air outlet pipe (21), and the air intake pipe (16) and the air outlet pipe (21) are both arranged in the heat exchange mechanism; The working well group includes a plurality of working wells (20), each of which is arranged at intervals of 20m to 150m. The two ends of the working wells (20) extend to the ground and the bottom of the underground water-bearing or saltwater layer (26), respectively. The wall portion of each working well (20) located in the underground water-bearing or saltwater layer (26) is provided with perforations. The underground water-bearing or saltwater layer (26) is also connected to a plurality of monitoring wells (19), which are arranged around the periphery of the working well group. The two ends of the monitoring wells (19) extend to the ground and the bottom of the underground water-bearing or saltwater layer (26), respectively. At the bottom of the water layer (26), the well wall portion of each monitoring well (19) located in the underground water-bearing or saline water layer (26) is arranged with perforations; the underground water-bearing or saline water layer (26) is buried at a depth of 20m~150m underground, the thickness of the underground water-bearing or saline water layer (26) is 50m~150m, the permeability is higher than 0.1 Darcy, and the porosity is greater than 0.1; the capillary breakthrough pressure of the dense cap layer (25) is more than 1.5 times the hydrostatic pressure of the formation at the same depth, the thickness is more than 10m, and its permeability is lower than the permeability of the underground water-bearing or saline water layer (26).

2. The seasonal compressed air energy storage system according to claim 1, characterized in that: The monitoring well (19) maintains a distance of 30m-80m from the working well group.

3. The seasonal compressed air energy storage system according to claim 1 or 2, characterized in that: The compressor unit comprises a low-pressure compressor (1), a medium-pressure compressor (3) and a high-pressure compressor (5); the air intake pipe (16) comprises a first pipe (161), a second pipe (162) and a third pipe (163); the air intake of the low-pressure compressor (1) is communicated with an air source, and the air outlet is connected to the air intake of the medium-pressure compressor (3) through the first pipe (161); the air outlet of the medium-pressure compressor (3) is connected to the air intake of the high-pressure compressor (5) through the second pipe (162); the air outlet of the high-pressure compressor (5) is connected to the working well group through the third pipe (163); the air intake valve (17) is provided on the third pipe (163); the first pipe (161), the second pipe (162) and the third pipe (163) are all provided in the heat exchange mechanism.

4. The seasonal compressed air energy storage system according to claim 3, characterized in that: The turbine unit comprises a high-pressure turbine (13) and a low-pressure turbine (15); the outlet pipe (21) comprises a fourth pipe (211) and a fifth pipe (212); the air inlet of the high-pressure turbine (13) is connected to the working well group via the fourth pipe (211); the air outlet is connected to the air inlet of the low-pressure turbine (15) via the fifth pipe (212); the air outlet of the low-pressure turbine (15) is communicated with the atmosphere; the fourth pipe (211) and the fifth pipe (212) are both arranged in the heat exchange mechanism.

5. The seasonal compressed air energy storage system according to claim 4, characterized in that: The heat exchange mechanism comprises a heat storage tank (7), a cold storage tank (11), a first heat exchanger (2), a second heat exchanger (4), a third heat exchanger (6), a fourth heat exchanger (12), a fifth heat exchanger (14), and a sixth heat exchanger (23); the first heat exchanger (2), the second heat exchanger (4), and the third heat exchanger (6) are connected in parallel between the inlet of the heat storage tank (7) and the outlet of the cold storage tank (11); the fourth heat exchanger (12) and the fifth heat exchanger (14) are connected in parallel between the outlet of the heat storage tank (7) and the outlet of the cold storage tank (11); The sixth heat exchanger (23) is connected to the air outlet end of the low-pressure turbine (15) and is connected to the inlet of the heat storage tank (7). The first pipe (161) is passed through the first heat exchanger (2), the second pipe (162) is passed through the second heat exchanger (4), the third pipe (163) is passed through the third heat exchanger (6), the fourth pipe (211) is passed through the fourth heat exchanger (12), and the fifth pipe (212) is passed through the fifth heat exchanger (14).

6. A seasonal compressed air energy storage method, characterized in that: The seasonal compressed air energy storage system according to any one of claims 1 to 5 is used, and mainly comprises the following steps: S1. Buffer gas injection: open the air inlet valve (17), close the air outlet valve (18), start the power mechanism (9) to drive the compressor unit to operate, inject a predetermined amount of buffer gas into the underground water-bearing or saline layer (26) through the working well group to form an initial air bag, and then close the air inlet valve (17); S2. Energy storage: During the off-peak season, the second linkage mechanism (10) is disconnected, the first linkage mechanism (8) is connected, the air inlet valve (17) is opened, and the air outlet valve (18) is closed. The power mechanism (9) is started to drive the compressor unit to operate, and a predetermined amount of energy storage gas is injected into the underground water-bearing or saline aquifer (26) through the working well group. The air inlet valve (17) is then closed to achieve electrical energy storage. S3. Energy release: During the peak electricity consumption season, the second linkage mechanism (10) is connected, the first linkage mechanism (8) is disconnected, the air inlet valve (17) is closed, and the air outlet valve (18) is opened. The air in the underground aquifer or saline layer (26) is discharged through the working well group, driving the turbine unit to operate. The turbine unit drives the power mechanism (9) to operate to supply power to users, thereby achieving energy release.

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