Underground compressed air energy storage device and method using coal mine geothermal

Abstract

This invention belongs to the field of underground energy storage and geothermal utilization technology, and particularly relates to an underground compressed air energy storage device and method utilizing coal mine geothermal energy, comprising: an underground storage tank, a geothermal utilization system, and a surface compression power generation system. This method achieves efficient energy storage through phased control of the geothermal utilization system: during the compression phase, the system is shut down, and high-pressure air is injected into the storage tank, storing the heat of compression in the surrounding rock; during the storage phase, the system is turned on, extracting geothermal energy through a heat absorption module, and heating the air through a heat transfer module to increase its potential energy; during the discharge phase, the system is shut down, releasing the air to generate electricity and absorbing heat from the surrounding rock. This invention couples geothermal replenishment with the energy storage process, significantly increasing the initial temperature and potential energy of the air during power generation, solving the problem of thermal energy management imbalance in traditional methods, and achieving efficient utilization of geothermal resources and increased discharge capacity.

Description

Technical Field

[0001] This invention belongs to the field of underground energy storage and geothermal utilization technology, and particularly relates to an underground compressed air energy storage device and method utilizing coal mine geothermal energy. Background Technology

[0002] Compressed air energy storage (CAES), as a large-scale, long-term energy storage technology, is of great significance for balancing grid peak and off-peak periods and absorbing intermittent clean energy sources such as wind and solar power. Among numerous potential underground storage options, the underground spaces of abandoned coal mines, such as roadways and chambers, are considered highly promising gas storage sites due to their readily available spatial structure, stable geological conditions, and relatively low development costs. However, directly applying traditional compressed air energy storage technology to abandoned coal mines has revealed a series of significant technical defects, severely restricting its energy storage efficiency and economic viability.

[0003] Research on existing technologies reveals that the core of their technical shortcomings lies in the imbalance of thermal energy management. Specifically, in the compression storage stage, an electrically driven compressor compresses air to a high-pressure state and injects it into the underground storage tank, releasing a large amount of compression heat. In traditional methods, this heat can only be passively conducted to the surrounding rock through the tank walls. Although some storage occurs, there is a lack of effective active control. Then, in the high-pressure air storage stage, due to heat exchange between the tank and the surrounding rock, the temperature of the high-pressure air gradually decreases, leading to a decay in its molecular potential energy (manifested as temperature and pressure), resulting in insufficient "initial potential energy" for subsequent power generation. When the grid needs power and the potential energy discharge stage begins, the high-pressure air needs to expand to drive the turbine for power generation, and this expansion process is a strong endothermic process. At this time, the system can only absorb heat from the nearby surrounding rock that has already been heated in the compression stage. If the surrounding rock temperature is insufficient or heat replenishment is not timely, the air temperature will further decrease, weakening the expansion's ability to generate work, ultimately resulting in low power generation efficiency and unsatisfactory discharge.

[0004] On the other hand, deep abandoned coal mines actually contain abundant geothermal resources, and the temperature of their tunnels or chambers can usually be maintained at 35°C or even higher under natural conditions.

[0005] By utilizing the abundant geothermal resources hidden in deep abandoned coal mines, the aforementioned heat loss can be compensated for and system efficiency improved. However, existing technologies lack an effective mechanism to organically integrate this stable geothermal resource with the dynamic process of compressed air energy storage, resulting in energy idleness and waste.

[0006] Therefore, there is an urgent need for an underground compressed air energy storage device and method that utilizes geothermal energy from coal mines to solve this problem. Summary of the Invention

[0007] The purpose of this invention is to provide an underground compressed air energy storage device and method utilizing geothermal energy in coal mines to solve the above-mentioned problems.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] An underground compressed air energy storage device utilizing geothermal energy from coal mines, comprising:

[0010] An underground storage facility, wherein a sealing mechanism forms an air storage space on its inner side for storing compressed air.

[0011] The outer side of the gas storage space consists of the storage wall, the adjacent surrounding rock, and the outer surrounding rock, with the storage wall and the adjacent surrounding rock arranged for heat exchange.

[0012] The gas storage space has a geothermal utilization system for heat exchange, which includes a heat utilization module, a heat transfer module, and a heat absorption module.

[0013] The heat absorption module is installed inside the surrounding rock, and the heat utilization module is installed inside the reservoir wall. The heat utilization module and the heat absorption module exchange heat through a heat transfer module.

[0014] The heat absorption module is configured to exchange heat with the surrounding rock.

[0015] The heat utilization module is configured to exchange heat with the gas storage space.

[0016] The underground storage facility is connected to an air compressor and an air generator located on the ground via a coal mine shaft. The air compressor is connected to a clean energy power supply system, and the air generator is connected to the power grid.

[0017] Optionally, the air compression mechanism includes an electric motor and a compressor. The electric motor is connected to the clean energy power supply system, the electric motor is connected to the compressor, and the air outlet of the compressor is connected to the coal mine shaft.

[0018] Optionally, the air-generating mechanism includes an expander and a generator, the air inlet of the expander is connected to the coal mine shaft, the expander is connected to the generator, and the generator is connected to the power grid.

[0019] Optionally, the heat absorption module is a pipe network array embedded in the surrounding rock, the pipe network array is configured to exchange heat with the surrounding rock, and the pipe network array is used to absorb geothermal energy in the surrounding rock.

[0020] Optionally, the storage wall includes a sealing layer and a concrete lining, the concrete lining being in contact with the adjacent surrounding rock and heat exchanged, and the sealing layer serving as the inner wall of the gas storage space.

[0021] The heat utilization module is disposed between the sealing layer and the concrete lining.

[0022] Optionally, the heat utilization module includes a heat exchange layer and a material layer arranged sequentially along the sealing layer toward the concrete lining.

[0023] The compressed air, the sealing layer, the heat exchange layer, the material layer, and the concrete lining are configured for heat exchange.

[0024] Optionally, the heat transfer module includes a three-way control valve, a circulating pump, and a heat transfer medium pipeline.

[0025] One end of the heat-conducting medium pipeline is connected to the pipe network array, and the other end of the heat-conducting medium pipeline is connected to the heat exchange layer through the three-way control valve and the circulating pump. Antifreeze flows in the heat exchange layer, the heat-conducting medium pipeline, and the pipe network array.

[0026] Optionally, the natural temperature of the coal mine shaft is not less than 35°C.

[0027] Optionally, a controller, a temperature sensor, and a pressure sensor are provided between the heat exchange layer and the material layer.

[0028] The controller is connected to the temperature sensor and the pressure sensor.

[0029] The controller is connected to the motor.

[0030] The controller is connected to the three-way control valve.

[0031] A method for using an underground compressed air energy storage device utilizing geothermal energy in a coal mine, comprising a compression energy storage stage, a high-pressure air storage stage, and a potential energy discharge stage.

[0032] During the compression and energy storage phase, the geothermal utilization system and the air power generation mechanism are shut down. The air compression mechanism pumps gas into the gas storage space. At this time, the heat released by the conversion of air kinetic energy into potential energy is directly transferred to the adjacent surrounding rock through the storage wall.

[0033] During the high-pressure air storage stage, the air compression mechanism and the air power generation mechanism are shut down, and the geothermal utilization system transfers the geothermal energy from the surrounding rock into the gas storage space to increase the molecular potential energy of the high-pressure air.

[0034] During the potential energy discharge stage, the geothermal utilization system and the air compression mechanism are shut down. The air power generation mechanism generates electricity by releasing high-pressure air and supplies it to the power grid. At this time, the heat absorbed by the air potential energy is converted into kinetic energy and moves from the adjacent surrounding rock through the storage wall into the gas storage space.

[0035] Compared with the prior art, the present invention has the following advantages and technical effects:

[0036] This invention achieves a significant improvement in energy storage efficiency by coordinating the phased intelligent control of the geothermal utilization system and the compressed air energy storage process. This method innovatively utilizes natural geothermal resources in abandoned coal mine roadways or chambers. During the high-pressure air storage stage, it actively activates the heat absorption and heat transfer modules, continuously transporting geothermal energy from the surrounding rock to the storage tank to heat the compressed air, significantly increasing its molecular potential energy. Simultaneously, the compression heat stored in the adjacent surrounding rock during the compression energy storage stage can be effectively utilized during the potential energy discharge stage, providing a stable heat source for air expansion. This precise thermal management ensures that the initial temperature and potential energy of the air during power generation are much higher than in traditional systems, directly translating into an effective increase in discharge. The entire device operates reliably through automatic regulation by a controller based on data from temperature and pressure sensors. This system not only efficiently utilizes the geothermal resources of abandoned mines, achieving cascaded energy utilization, but also ensures long-term stability in the high-temperature environment of deep wells through modular design and antifreeze media. It provides an economical, safe, and efficient solution to the problem of low efficiency caused by thermal imbalance in traditional compressed air energy storage in abandoned coal mines. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 This is a schematic diagram of the structure of the present invention.

[0039] Figure 2 This is a schematic diagram of the geothermal utilization system of the present invention.

[0040] The components include: 1. Clean energy power supply system; 2. Electric motor; 3. Compressor; 4. Expander; 5. Generator; 6. Power grid; 7. Coal mine shaft; 8. Storage tank wall; 9. Compressed air; 10. Sealing mechanism; 11. Heat utilization module; 12. Heat transfer module; 13. Heat absorption module; 14. Sealing layer; 15. Heat exchange layer; 16. Concrete lining; 17. Adjacent surrounding rock; 18. Surrounding rock; 19. Material layer; 20. Controller; 21. Temperature sensor; 22. Pressure sensor; 23. Three-way control valve; 24. Circulating pump; 25. Heat transfer medium pipeline. Detailed Implementation

[0041] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] Reference Figures 1 to 2 This invention discloses an underground compressed air energy storage device utilizing geothermal energy in coal mines, comprising:

[0044] An underground storage facility, which forms a storage space for storing compressed air 9 on its inner side through a sealing mechanism 10.

[0045] The outer side of the gas storage space consists of the storage wall 8, the adjacent surrounding rock 17, and the outer surrounding rock 18. The storage wall 8 and the adjacent surrounding rock 17 are equipped for heat exchange.

[0046] The gas storage space has a geothermal utilization system for heat exchange, which includes a heat utilization module 11, a heat transfer module 12, and a heat absorption module 13.

[0047] The heat absorption module 13 is installed inside the surrounding rock 18, and the heat utilization module 11 is installed inside the storage wall 8. The heat utilization module 11 and the heat absorption module 13 are connected by heat exchange through the heat transfer module 12.

[0048] The heat absorption module 13 is configured to exchange heat with the surrounding rock 18.

[0049] The heat utilization module 11 is configured to exchange heat with the gas storage space.

[0050] The underground storage facility is connected to an air compressor and an air generator located on the ground via a coal mine shaft 7. The air compressor is connected to a clean energy power supply system 1, and the air generator is connected to the power grid 6.

[0051] The coal mine shaft 7 is connected to the air compressor and air generator located on the ground through a three-way solenoid valve. The three-way solenoid valve can control three states: the air compressor is connected to the coal mine shaft 7, the air generator is connected to the coal mine shaft 7, and both the air compressor and the air generator are disconnected from the coal mine shaft 7.

[0052] This device is implemented in the roadways or chambers of abandoned coal mines and is divided into the following phased control processes:

[0053] Compression and storage stage: The geothermal utilization system is shut down, and the high-pressure air generated by the electrically driven compressor 3 is injected into the underground storage tank. During this stage, the kinetic energy of the air is converted into potential energy, releasing heat, which is directly transferred to the adjacent surrounding rock 17 through the storage tank wall 8.

[0054] High-pressure air storage stage: The geothermal utilization system is turned on, and the heat absorption module 13 installed in the surrounding rock 18 of the storage tank is activated to transfer the geothermal energy of the surrounding rock to the inside of the storage tank, heating the stored high-pressure air to increase its molecular potential energy.

[0055] Potential energy discharge stage: The geothermal utilization system is shut down, and high-pressure air is released to drive the turbine to generate electricity. During this stage, the potential energy of the air is converted into kinetic energy, absorbing heat, which is then extracted from the adjacent surrounding rock 17 through the reservoir wall 8.

[0056] This method uses high-pressure air at a higher temperature than conventional compressed air energy storage in abandoned coal mines, resulting in higher initial potential energy and the ability to release more electricity.

[0057] Furthermore, the geothermal utilization system includes a heat absorption module 13, a heat transfer module 12, and a heat utilization module 11.

[0058] The heat absorption module 13 is arranged in the surrounding rock 18 to absorb geothermal energy.

[0059] The heat utilization module 11 is arranged between the concrete lining 16 and the sealing layer 14 of the tunnel storage tank to increase the temperature of the compressed air during the high-pressure air storage stage.

[0060] The heat transfer module 12 is connected to the heat absorption module 13 and the heat utilization module 11.

[0061] The operation of this device strictly follows a phased intelligent control strategy to achieve efficient energy conversion. First, in the compression and storage phase, the clean energy power supply system 1 supplies power, driving the air compressor mechanism. At this time, the three-way solenoid valve on the ground controls the air compressor mechanism to connect with the coal mine shaft 7. The generated high-pressure compressed air 9 is injected through the coal mine shaft 7 into the gas storage space of the underground storage tank formed by the sealing mechanism 10. During this phase, the geothermal utilization system is set to the off state, and the heat released during the compression process is directly transferred through the storage tank wall 8 to the adjacent surrounding rock 17 where it exchanges heat for storage. Subsequently, the system enters the high-pressure air storage phase, and the geothermal utilization system is activated: the heat absorption module 13, arranged within the surrounding rock 18, begins to absorb geothermal heat, and the heat transfer module 12 is activated, transferring heat to the heat utilization module 11, located within the storage tank wall 8. This module exchanges heat with the compressed air 9 in the gas storage space, thereby actively and continuously heating it and significantly increasing its molecular potential energy. When power generation is needed, the system enters the potential energy discharge stage, shuts down the geothermal utilization system again, and the three-way solenoid valve on the ground switches to connect the air-powered generator to the coal mine shaft 7. Compressed air 9 is released, driving the air-powered generator to do work, and the generated electricity is transmitted to the power grid 6. The heat required for this expansion and heat absorption process is obtained from the adjacent surrounding rock 17 through the heat utilization module 11 and the storage wall 8. This device actively manages the compressed air 9 in the gas storage space through the geothermal utilization system at key stages, and uses the coal mine shaft 7 as a channel, combined with the sealing mechanism 10 to ensure airtightness. Ultimately, the initial temperature and potential energy of the air during power generation are much higher than those of conventional systems, effectively solving the problem of low efficiency caused by the imbalance of thermal energy management in traditional abandoned coal mine compressed air energy storage. It achieves efficient synergy between geothermal resources and compressed air energy storage technology, ultimately resulting in a significant increase in discharge.

[0062] As an optional implementation, the air compression mechanism includes an electric motor 2 and a compressor 3. The electric motor 2 is connected to the clean energy power supply system 1, the electric motor 2 is connected to the compressor 3, and the air outlet of the compressor 3 is connected to the coal mine shaft 7.

[0063] During the compression and energy storage stage, the clean energy power supply system 1 drives the motor 2 to operate, which in turn drives the compressor 3 to work. The compressed air generated is injected into the underground storage tank through the coal mine shaft 7 via its outlet, realizing the efficient and zero-carbon emission conversion of electrical energy into high-pressure air potential energy.

[0064] As an optional implementation, the air-powered generator includes an expander 4 and a generator 5. The air inlet of the expander 4 is connected to the coal mine shaft 7, the expander 4 is connected to the generator 5, and the generator 5 is connected to the power grid 6.

[0065] During the potential energy discharge stage, the high-pressure compressed air 9 stored in the underground storage is released through the coal mine shaft 7, driving the expander 4 to operate. The expander 4 converts the potential energy of the air into mechanical energy, which in turn drives the generator 5 to generate electricity. The generated electricity is finally transmitted to the power grid 6, completing the final efficient conversion of compressed air potential energy into electrical energy.

[0066] As an optional implementation, the heat absorption module 13 is a pipe network array embedded in the surrounding rock 18. The pipe network array is configured to exchange heat with the surrounding rock 18 and is used to absorb geothermal energy within the surrounding rock 18.

[0067] The heat absorption module 13 is a pipe network array embedded in the surrounding rock 18. Its performance requirements are: the heat replenished by the surrounding rock 18 in a single cycle when the geothermal utilization system is shut down > the heat absorption capacity of the pipe network array > the heat loss of the heat transfer module 12.

[0068] During the high-pressure air storage stage, the heat absorption module 13, i.e. the pipeline array, embedded in the surrounding rock 18, continuously and stably absorbs the geothermal energy in it through heat exchange with the surrounding rock 18, providing a high-temperature and reliable heat source for the entire geothermal utilization system, and effectively improving the subsequent heating efficiency of the compressed air 9.

[0069] As an optional implementation, the storage wall 8 includes a sealing layer 14 and a concrete lining 16, the concrete lining 16 being in contact with and heat-exchanging with the adjacent surrounding rock 17, and the sealing layer 14 serving as the inner wall of the gas storage space.

[0070] The heat utilization module 11 is disposed between the sealing layer 14 and the concrete lining 16.

[0071] During the high-pressure air storage stage, the heat utilization module 11, located between the sealing layer 14 and the concrete lining 16, efficiently transfers geothermal heat to the gas storage space, directly heating the compressed air 9. During the potential energy discharge stage, the heat exchange arrangement between the concrete lining 16 and the adjacent surrounding rock 17 ensures that the expansion heat absorption process can stably obtain the required heat from the surrounding rock, while the sealing layer 14 reliably maintains the airtightness of the gas storage space.

[0072] As an optional implementation, the heat utilization module 11 includes a heat exchange layer 15 and a material layer 19 arranged sequentially along the sealing layer 14 toward the concrete lining 16.

[0073] The heat exchange system consists of compressed air 9, sealing layer 14, heat exchange layer 15, material layer 19, and concrete lining 16.

[0074] The heat utilization module 11 includes a material layer 19 that can release geothermal heat, a temperature sensor 21, a pressure sensor 22, and a controller 20.

[0075] Material layer 19 can be flexibly disassembled and replaced, and has a service life of ≥1 day.

[0076] During the high-pressure air storage phase, the geothermal utilization system is activated, and heat is transferred to the heat utilization module 11 via the heat transfer module 12. The material layer 19 stores and releases heat, while the heat exchange layer 15 promotes efficient heat transfer, allowing heat to pass sequentially through the material layer 19, the heat exchange layer 15, and the sealing layer 14, ultimately heating the compressed air 9 within the storage space. During the potential energy discharge phase, the material layer 19 provides a stable auxiliary heat source, and the heat exchange layer 15 ensures that the compressed air 9 can efficiently absorb heat from the adjacent surrounding rock 17 through the concrete lining 16 when it expands. This structure significantly optimizes the thermal management efficiency within the storage facility.

[0077] As an optional implementation, the heat transfer module 12 includes a three-way control valve 23, a circulating pump 24, and a heat transfer medium pipeline 25.

[0078] One end of the heat transfer medium pipeline 25 is connected to the pipe network array, and the other end of the heat transfer medium pipeline 25 is connected to the heat exchange layer 15 through the three-way control valve 23 and the circulation pump 24. Antifreeze flows in the heat exchange layer 15, the heat transfer medium pipeline 25 and the pipe network array.

[0079] The heat transfer module 12 includes a circulating pump 24, a three-way control valve 23, and a heat transfer medium pipeline 25.

[0080] The circulating pump 24 drives the antifreeze in the heat transfer medium pipeline 25 to circulate between the heat absorption module 13 and the heat transfer module 12.

[0081] The three-way control valve 23 opens the heat exchange circuit during the high-pressure air storage stage and closes the circuit during the other stages.

[0082] The antifreeze aqueous solution flowing in the heat transfer medium pipe 25 has a freezing point ≤ -20℃ and a boiling point ≥ 110℃.

[0083] During the high-pressure air storage phase, the circulation pump 24 starts and the three-way control valve 23 opens the circuit, driving the antifreeze to circulate in a closed loop consisting of the pipeline array of the heat absorption module 13, the heat transfer medium pipeline 25, and the heat exchange layer 15, efficiently transferring geothermal energy to the storage tank. During the compression energy storage and potential energy discharge phase, the three-way control valve 23 switches to the short-circuit circuit and the circulation pump 24 stops. This system characteristic ensures that heat is precisely delivered only during the required phases, while the antifreeze ensures the safe and stable operation of the pipeline in the complex temperature environment downhole.

[0084] As an optional implementation, the natural temperature of the coal mine shaft 7 is not less than 35°C.

[0085] The natural high temperature of the coal mine shaft 7 (≥35℃) provides a stable geothermal source for the heat absorption module 13, effectively improving the initial potential energy and power generation efficiency of the compressed air 9.

[0086] Under natural conditions, the temperature of abandoned coal mine roadways or chambers, which serve as coal mine shafts (7), needs to be no less than 35℃. Adjacent surrounding rock (17) refers to the rock mass that absorbs heat during a single potential energy discharge phase when the underground reservoir absorbs thermal energy. Surrounding surrounding rock (18) refers to the rock mass that is not affected by underground compressed air energy storage under natural conditions.

[0087] As an optional implementation, a controller 20, a temperature sensor 21, and a pressure sensor 22 are provided between the heat exchange layer 15 and the material layer 19.

[0088] The controller 20 is connected to the temperature sensor 21 and the pressure sensor 22.

[0089] The controller 20 is connected to the motor 2.

[0090] The controller 20 is connected to the three-way control valve 23.

[0091] Temperature sensor 21 and pressure sensor 22 monitor the pressure and temperature of compressed air transmitted to the sealing layer 14.

[0092] The controller 20 receives sensor data and feeds it back to the ground surface to control the timed opening and closing of the geothermal utilization system.

[0093] The controller 20 receives thermodynamic data from the temperature sensor 21 and pressure sensor 22 in real time, and intelligently controls the on / off state of the three-way control valve 23 and the start / stop of the motor 2 accordingly. This allows for precise management of the operation phase of the geothermal utilization system, achieving fully automated monitoring and optimized control of the compressed air 9 state, and significantly improving the system response speed and overall energy storage efficiency.

[0094] A method for using an underground compressed air energy storage device utilizing geothermal energy in a coal mine, comprising a compression energy storage stage, a high-pressure air storage stage, and a potential energy discharge stage.

[0095] During the compression and energy storage stage, the geothermal utilization system and the air power generation mechanism are shut down, and the air compression mechanism pumps gas into the gas storage space. At this time, the heat released by the conversion of air kinetic energy into potential energy is directly transferred to the adjacent surrounding rock 17 through the storage wall 8.

[0096] During the high-pressure air storage stage, the air compression mechanism and air power generation mechanism are shut down, and the geothermal utilization system transfers the geothermal energy from the surrounding rock 18 into the gas storage space to increase the molecular potential energy of the high-pressure air.

[0097] When in the potential energy discharge stage, the geothermal utilization system and air compression mechanism are shut down, and the air power generation mechanism generates electricity by releasing high-pressure air and supplies it to the power grid 6. At this time, the potential energy of the air is converted into kinetic energy and the absorbed heat moves from the adjacent surrounding rock 17 through the storage wall 8 into the gas storage space.

[0098] This method achieves efficient synergy between geothermal resources and compressed air energy storage by precisely controlling the start and stop of each system in stages. During the compression energy storage stage, the geothermal utilization system and the air power generation mechanism are shut down. The electric motor 2, driven by the clean energy power supply system 1, drives the compressor 3, generating high-pressure air which is injected into the storage space sealed by the sealing mechanism 10 through the coal mine shaft 7. During this process, the air kinetic energy is converted into potential energy, releasing compression heat, which is directly transferred through the storage wall 8 and stored in the adjacent surrounding rock 17. After entering the high-pressure air storage stage, the air compression mechanism and the air power generation mechanism are shut down, and the geothermal utilization system is activated: the heat absorption module 13, embedded in the surrounding rock 18, absorbs geothermal heat through its network array; the circulation pump 24 of the heat transfer module 12 drives the flow of the heat transfer medium pipeline 25; and the three-way control valve 23 opens the circuit, transferring heat to the heat utilization module 11 located between the sealing layer 14 and the concrete lining 16. Through its heat exchange layer 15 and material layer 19, the compressed air 9 in the storage space is continuously heated, significantly increasing its molecular potential energy. During the potential energy discharge stage, the geothermal utilization system and air compression mechanism are shut down, high-pressure air is released, driving expander 4 and generator 5 to operate and supply power to the grid 6. The heat required for this expansion and heat absorption process is obtained from the adjacent surrounding rock 17, which stores the heat of compression, through the storage wall 8. Throughout the process, controller 20 intelligently controls actuators such as the three-way control valve 23 and motor 2 based on monitoring data from temperature sensor 21 and pressure sensor 22, ensuring seamless switching between stages. The core effect of this method is that, through active geothermal replenishment and staged thermal energy management, the initial temperature and potential energy of the compressed air 9 during the discharge stage are much higher than those of conventional systems, thereby significantly improving power generation efficiency and discharge capacity.

[0099] The present invention discloses an underground compressed air energy storage device and method utilizing geothermal energy in coal mines, implemented in roadways or chambers of abandoned coal mines, and the implementation steps are as follows:

[0100] Step 1: Select an abandoned coal mine roadway or chamber as the storage space, ensuring the natural temperature is ≥35℃. Confirm the zoning of the adjacent surrounding rock 17 (rock mass that absorbs heat during a single potential energy discharge stage) and the outer surrounding rock 18 (rock mass that is unaffected under natural conditions).

[0101] Step 2: Install the geothermal utilization system: The heat absorption module 13 is arranged in the surrounding rock 18 using an embedded pipe network array. The heat utilization module 11 is arranged between the concrete lining 16 and the sealing layer 14 of the tunnel storage tank. The heat transfer module 12 connects the above modules. The performance of the heat absorption module 13 must meet the following requirements: heat replenishment from the surrounding rock 18 in a single cycle > heat absorption capacity of the pipe network array > heat loss from the heat transfer module 12.

[0102] Step 3, Compression and Energy Storage Stage: The geothermal utilization system is shut down, and the high-pressure air generated by the electrically driven compressor 3 is injected into the underground storage tank. The heat released by the conversion of the air's kinetic energy into potential energy is directly transferred to the adjacent surrounding rock 17 through the storage tank wall 8. During this stage, the three-way control valve 23 of the heat transfer module 12 disconnects the circuit, and the circulation pump 24 stops working.

[0103] Step 4, High-Pressure Air Storage Stage: The geothermal utilization system is activated, and the pipe network array of the heat absorption module 13 is activated to absorb geothermal energy from the surrounding rock 18. The circulation pump 24 of the heat transfer module 12 drives the heat transfer medium pipe 25 (antifreeze aqueous solution, freezing point ≤ -20℃, boiling point ≥ 110℃) to circulate between modules. The three-way control valve 23 opens the heat exchange circuit, and heat is transferred to the heat utilization module 11 to heat the stored high-pressure air to increase its molecular potential energy.

[0104] Step 5, Potential Energy Discharge Stage: The geothermal utilization system is shut down, and high-pressure air is released to drive the turbine for power generation. The potential energy of the air is converted into kinetic energy, and the absorbed heat is extracted from the adjacent surrounding rock 17 through the storage wall 8. During this stage, the material layer 19 of the heat utilization module 11 (removable and replaceable, with a service life of ≥1 day) assists in heat transfer, and the temperature sensor 21 and pressure sensor 22 monitor the data in real time.

[0105] Step 6: The controller 20 receives monitoring data from the temperature sensor 21 and the pressure sensor 22 in real time, feeds it back to the ground surface, and automatically controls the timed opening and closing of the geothermal utilization system to ensure that the high-pressure air temperature is higher than that of conventional methods, the initial potential energy is increased, and the discharge amount is increased.

[0106] Step 7: After completing a single cycle, check the system status: Replace the material layer 19 of the heat utilization module 11 according to its wear condition. Replenish or replace the antifreeze in the heat transfer medium pipeline 25. Verify the performance of the pipeline array. Repeat steps 3 to 6 for continuous operation. This method maximizes the utilization of geothermal resources and improves energy storage efficiency through phased intelligent control.

[0107] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0108] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. An underground compressed air energy storage device utilizing geothermal energy in coal mines, characterized in that, include: An underground storage facility, wherein a sealing mechanism (10) forms an air storage space on its inner side for storing compressed air (9); The outer side of the gas storage space consists of the storage wall (8), the adjacent surrounding rock (17), and the outer surrounding rock (18) in sequence. The storage wall (8) and the adjacent surrounding rock (17) are heat exchanged. The gas storage space has a geothermal utilization system for heat exchange, which includes a heat utilization module (11), a heat transfer module (12), and a heat absorption module (13). The heat absorption module (13) is installed inside the surrounding rock (18), the heat utilization module (11) is installed inside the reservoir wall (8), and the heat utilization module (11) and the heat absorption module (13) are heat exchanged through the heat transfer module (12). The heat absorption module (13) is configured to exchange heat with the surrounding rock (18); The heat utilization module (11) is configured to exchange heat with the gas storage space; The underground storage is connected to an air compressor and an air generator located on the ground through a coal mine shaft (7). The air compressor is connected to a clean energy power supply system (1), and the air generator is connected to the power grid (6). The heat absorption module (13) is a pipe network array embedded in the surrounding rock (18). The pipe network array is heat exchanged with the surrounding rock (18). The pipe network array is used to absorb geothermal energy in the surrounding rock (18). The storage wall (8) includes a sealing layer (14) and a concrete lining (16). The concrete lining (16) is in contact with the adjacent surrounding rock (17) and is heat exchanged. The sealing layer (14) serves as the inner wall of the gas storage space. The heat utilization module (11) is disposed between the sealing layer (14) and the concrete lining (16); The heat utilization module (11) includes a heat exchange layer (15) and a material layer (19) arranged sequentially along the sealing layer (14) toward the concrete lining (16). The compressed air (9), the sealing layer (14), the heat exchange layer (15), the material layer (19) and the concrete lining (16) are heat exchanged. The heat transfer module (12) includes a three-way control valve (23), a circulation pump (24), and a heat transfer medium pipeline (25). One end of the heat transfer medium pipeline (25) is connected to the pipeline array, and the other end of the heat transfer medium pipeline (25) is connected to the heat exchange layer (15) through the three-way control valve (23) and the circulating pump (24). Antifreeze flows in the heat exchange layer (15), the heat transfer medium pipeline (25) and the pipeline array. It also includes a compression energy storage stage, a high-pressure air storage stage, and a potential energy discharge stage; When in the compression energy storage stage, the geothermal utilization system and the air power generation mechanism are shut down, and the air compression mechanism pumps gas into the gas storage space. At this time, the heat released by the conversion of air kinetic energy into potential energy is directly transferred to the adjacent surrounding rock (17) through the storage wall (8). When in the high-pressure air storage stage, the air compression mechanism and the air power generation mechanism are closed, and the geothermal utilization system transmits the geothermal energy in the surrounding rock (18) into the gas storage space to increase the molecular potential energy of the high-pressure air; When in the potential energy discharge stage, the geothermal utilization system and the air compression mechanism are shut down. The air power generation mechanism generates electricity by releasing high-pressure air and supplies it to the power grid (6). At this time, the heat absorbed by the air potential energy is converted into kinetic energy and moves from the adjacent surrounding rock (17) through the storage wall (8) into the gas storage space.

2. The underground compressed air energy storage device utilizing geothermal energy in coal mines according to claim 1, characterized in that: The air compression mechanism includes an electric motor (2) and a compressor (3). The electric motor (2) is connected to the clean energy power supply system (1), and the electric motor (2) is connected to the compressor (3). The air outlet of the compressor (3) is connected to the coal mine shaft (7).

3. The underground compressed air energy storage device utilizing geothermal energy in coal mines according to claim 1, characterized in that: The air-generating mechanism includes an expander (4) and a generator (5). The air inlet of the expander (4) is connected to the coal mine shaft (7). The expander (4) is connected to the generator (5). The generator (5) is connected to the power grid (6).

4. The underground compressed air energy storage device utilizing geothermal energy in coal mines according to claim 1, characterized in that: The natural temperature of the coal mine shaft (7) is not less than 35℃.

5. The underground compressed air energy storage device utilizing geothermal energy in coal mines according to claim 1, characterized in that: A controller (20), a temperature sensor (21), and a pressure sensor (22) are provided between the heat exchange layer (15) and the material layer (19). The controller (20) is connected to the temperature sensor (21) and the pressure sensor (22).

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