Compressed air energy storage device based on aquifer and operation method of compressed air energy storage device

Abstract

The invention discloses a compressed air energy storage device based on an aquifer and an operation method of the compressed air energy storage device, and relates to the technical field of compressed air. Specifically, the earth surface facility is used for compressing outside air to an underground water storage layer during the low-energy demand period and releasing compressed air to generate electricity during the high-energy demand period; and the underground water storage layer is used for injecting, storing and releasing compressed air. According to the invention, the ubiquitous underground aquifer is used as the underground reservoir, so that the dependence on special geological conditions is reduced, and the application range of the energy storage system is expanded; by utilizing the natural geologic structure characteristics, the construction cost of the energy storage system is reduced, the medium-and-long-term energy storage requirement can be met, the instability caused by renewable energy sources is balanced, the energy storage efficiency is greatly improved, and the method has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air, and more particularly to a compressed air energy storage device based on an aquifer and an operating method thereof. Background Art

[0002] There are many types of energy storage technologies available, but pumped storage and compressed air storage are two technologies that can currently provide large-scale (power>100MW) and long-term energy storage. Pumped storage is a mature and widely used technology for utility-scale commercial energy storage, but its development is limited by finding suitable locations, resulting in a large number of areas being unable to use pumped storage for energy storage.

[0003] Therefore, how to utilize the ubiquitous existence of aquifers and design a compressed air energy storage device based on aquifers is a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0004] In view of this, the present invention provides an aquifer-based compressed air energy storage device and an operating method thereof, which solves the problems existing in the background technology.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An aquifer-based compressed air energy storage device, comprising: a surface facility and an underground aquifer;

[0007] Surface facilities that compress outside air into underground aquifers during periods of low energy demand and release the compressed air to generate electricity during periods of high energy demand;

[0008] Underground aquifers for the injection, storage and release of compressed air.

[0009] Optionally, the surface facilities include a blower, a compressor, a cooling system, a thermal energy storage system, a heating system and a turbine generator connected in sequence;

[0010] Blowers are used to operate when there is excess energy during periods of low electricity prices or when the grid load is low, and to draw in outside air;

[0011] A compressor, used to compress the inhaled air to a preset pressure;

[0012] A cooling system for absorbing heat energy from the compressed air and transferring the absorbed heat energy to a thermal energy storage system;

[0013] A heating system, used for heating the compressed air by utilizing the thermal energy stored in the thermal energy storage system during the compressed air release process;

[0014] A turbine generator is used to generate electricity when compressed air is released.

[0015] Optionally, the underground aquifer includes an aquifer and an injection / production well, the injection / production well being drilled into the aquifer;

[0016] Aquifers, used as storage spaces for compressed air;

[0017] Injection / production wells, used for injection and release of compressed air.

[0018] Optionally, it also includes a first pipeline system, which connects the blower, the compressor, the cooling system and the injection / production well in sequence to complete the injection and storage process of compressed air.

[0019] Optionally, a second pipeline system is also included, which is connected in sequence to the injection / production well, the heating system and the turbine generator to complete the compressed air release production process.

[0020] Optionally, it also includes a first gas cut-off valve and a second gas cut-off valve, the first gas cut-off valve is installed between the cooling system and the injection / production well, and the second gas cut-off valve is installed between the injection / production well and the heating system.

[0021] Optionally, the selection conditions of the aquifer are: permeability of 1000-5000mD, depth of 400-1200m, thickness of 6-40m, and inclination greater than 1:50.

[0022] Optionally, the compressor gradually increases the air pressure by using a multi-stage compression method, and cools the air through a cooling system after each stage of compression.

[0023] Optionally, the air injection pressure of the injection / production well does not exceed 150% of the initial pore pressure and the air extraction pressure is above 75% of the initial pressure.

[0024] A method for operating a compressed air energy storage device based on an aquifer, comprising the following steps:

[0025] During periods of low electricity prices or low grid load, excess energy is used to drive the blower to inhale air, which is then compressed by the compressor. The compressed air is cooled by the cooling system and the released heat energy is transferred to the thermal energy storage system. The cooled compressed air is injected into the aquifer through the injection / production well. The compressed air pushes the water in the aquifer to an area far away from the wellbore, forming air cushion bubbles, and the pressure in the aquifer gradually tends to balance.

[0026] When the grid load is high or the demand increases, compressed air is drawn from the aquifer through the injection / production wells and enters the heating system. The heating system uses the thermal energy in the thermal energy storage system to heat the compressed air. The heated air expands in the turbine generator and drives the blades to rotate, driving the turbine generator to generate electricity.

[0027] When the air in the aquifer is released, the air will be compressed by the blower, compressor and cooling system to store energy during the next low electricity consumption period, and then the heating system and turbine generator will release the air to generate electricity.

[0028] It can be seen from the above technical solutions that, compared with the prior art, the present invention discloses a compressed air energy storage device based on an aquifer and an operating method thereof, which has the following beneficial effects: using the ubiquitous underground aquifer as an underground reservoir reduces the dependence on special geological conditions and expands the scope of application of the energy storage system; utilizing the natural geological structure characteristics to reduce the construction cost of the energy storage system. In addition, the aquifer has a natural buffering effect as an energy storage medium, and the uniform diffusion of compressed air in the aquifer can reduce the risk of leakage; the energy storage characteristics of the aquifer are only related to its own geological characteristics and have nothing to do with seasons, temperature and other conditions. Therefore, it can meet the medium- and long-term energy storage needs, balance the instability caused by renewable energy, greatly improve the energy storage efficiency, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention 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 invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0030] Figure 1 A schematic diagram of the structure of the aquifer-based compressed air energy storage device provided by the present invention;

[0031] Figure numerals: 1 - blower, 2 - compressor, 3 - cooling system, 4 - thermal energy storage system, 5 - heating system, 6 - turbine generator, 7 - injection / production well, 8 - aquifer, 9 - first pipeline system, 10 - second pipeline system, 11 - first shut-off valve, 12 - second shut-off valve. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] The embodiment of the present invention discloses a compressed air energy storage device based on an aquifer, such as Figure 1 As shown, it includes: surface facilities and underground aquifers;

[0034] Surface facilities that compress outside air into underground aquifers during periods of low energy demand and release the compressed air to generate electricity during periods of high energy demand;

[0035] Underground aquifers for the injection, storage and release of compressed air.

[0036] Further, the surface facility includes a blower 1, a compressor 2, a cooling system 3, a thermal energy storage system 4, a heating system 5 and a turbine generator 6 connected in sequence; wherein the cooling system 3, the thermal energy storage system 4 and the heating system 5 can constitute a heat transfer system;

[0037] The blower 1 is used to be driven by excess energy during a period of low electricity prices or a period of low grid load to operate and inhale outside air;

[0038] The compressor 2 is used to compress the sucked air to a preset pressure; specifically, the compressor 2 gradually increases the air pressure by a multi-stage compression method, and the air is cooled by the cooling system 3 after each stage of compression, which can reduce the temperature rise during the compression process and protect the subsequent equipment and the aquifer 8 environment;

[0039] The cooling system 3 is used to absorb the heat energy of the compressed air, reduce the air temperature, and transfer the absorbed heat energy to the thermal energy storage system 4, which can prevent the high-temperature air from damaging the waterproof layer structure; specifically, the cooling system 3 is configured to be connected to the thermal energy storage system 4 as a heat exchanger, and is used to transfer the heat generated by the compressed air to the thermal energy storage system 4 for storage during the air injection process;

[0040] The heating system 5 is used to heat the compressed air using the heat energy stored in the thermal energy storage system 4 during the compressed air release process, so that the compressed air expands rapidly; specifically, the heating system 5 is configured as a heat exchanger connected to the thermal energy storage system 4, and is used to heat the air using the heat stored in the thermal energy storage system 4 during the air release process, thereby improving the power generation efficiency;

[0041] The turbine generator 6 is used to generate electricity when the compressed air is released.

[0042] Further, the underground aquifer includes an aquifer 8 and an injection / production well 7, and the injection / production well 7 is drilled into the aquifer 8;

[0043] Aquifer 8 is used as a storage space for compressed air; among them, an aquifer 8 with appropriate permeability, depth, thickness and inclination should be selected, specifically, the permeability is 1000-5000mD, the depth is 400-1200m, the thickness is 6-40m, and the inclination is greater than 1:50.

[0044] Injection / production well 7 is used for the injection and release of compressed air. The design of injection / production well 7 needs to ensure that, during the injection and release of air, the bottom hole pressure does not exceed the bearing range of the rock formation to avoid geological fractures. In addition, to ensure safety, the air injection pressure of injection / production well 7 does not exceed 150% of the initial pore pressure, and the air extraction pressure is above 75% of the initial pressure.

[0045] In a specific embodiment, the compressed air energy storage device also includes a first pipeline system 9, which is connected to the blower 1, the compressor 2, the cooling system 3 and the injection / production well 7 in sequence. With the participation of the heat transfer system, the first pipeline system 9 is used to absorb external air into the compressed energy storage and release heat to complete the injection and storage process of compressed air.

[0046] In another specific embodiment, the compressed air energy storage device also includes a second pipeline system 10, which is sequentially connected to the injection / production well 7, the heating system 5 and the turbine generator 6, and is used to release the compressed air, drive the turbine generator 6 to work, absorb heat, and complete the compressed air release production process.

[0047] In another specific embodiment, the compressed air energy storage device also includes a first air shut-off valve 11 and a second air shut-off valve 12, the first air shut-off valve 11 is installed between the cooling system 3 and the injection / production well 7, and the second air shut-off valve 12 is installed between the injection / production well 7 and the heating system 5.

[0048] In specific implementation, when the first air cut-off valve 11 is opened and the second air cut-off valve 12 is closed, air is compressed into the underground aquifer through the injection / production well 7; when the first air cut-off valve 11 is closed and the second air cut-off valve 12 is opened, gas is released from the underground aquifer; when the first air cut-off valve 11 and the second air cut-off valve 12 are closed, the underground aquifer maintains gas mass balance.

[0049] and Figure 1 Corresponding to the device described above, this embodiment also discloses an operation method of a compressed air energy storage device based on an aquifer, comprising the following steps:

[0050] During the period of low electricity price or low load of the power grid, the excess energy is used to drive the blower 1 to operate and inhale air, and the inhaled air is compressed by the compressor 2, and the compressed air is cooled by the cooling system 3 and the released heat energy is transferred to the thermal energy storage system 4; the cooled compressed air is injected into the aquifer 8 through the injection / production well 7, and the compressed air pushes the water in the aquifer 8 to the area away from the wellbore to form air cushion bubbles, and the pressure in the aquifer 8 gradually tends to balance; the air in the aquifer 8 is in a high pressure state and can be used to release energy and generate electricity at any time;

[0051] When the grid load is high or the demand increases, compressed air is extracted from the aquifer 8 through the injection / production well 7 and enters the heating system 5. The heating system 5 uses the heat energy in the thermal energy storage system 4 to heat the compressed air. The heated air expands in the turbine generator 6 and drives the blades to rotate, driving the turbine generator 6 to generate electricity.

[0052] When the air in the aquifer 8 is released, the blower 1, compressor 2 and cooling system 3 will compress the air to store energy during the next low electricity consumption period, and then the heating system 5 and turbine generator 6 will release the air to generate electricity.

[0053] Furthermore, after the compressed air expands, it can enter the heating system 5 again for multiple heating to further improve the air utilization efficiency.

[0054] Furthermore, stable flow rate control is required during the expansion process to ensure that the turbine generator 6 operates at an optimal speed to achieve maximum efficiency in power output.

[0055] In this specification, each embodiment is described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the embodiments can be referred to each other. For the method disclosed in the embodiment, since it corresponds to the device disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the method part.

[0056] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A compressed air energy storage device based on an aquifer, characterized in that: include: surface facilities and underground aquifers; Surface facilities that compress outside air into underground aquifers during periods of low energy demand and release the compressed air to generate electricity during periods of high energy demand; Underground aquifers for the injection, storage and release of compressed air.

2. A compressed air energy storage device based on an aquifer according to claim 1, characterized in that: The surface facilities include blowers, compressors, cooling systems, thermal energy storage systems, heating systems and turbine generators connected in sequence; Blowers are used to operate when there is excess energy during periods of low electricity prices or when the grid load is low, and to draw in outside air; A compressor, used to compress the inhaled air to a preset pressure; A cooling system for absorbing heat energy from the compressed air and transferring the absorbed heat energy to a thermal energy storage system; A heating system, used for heating the compressed air by utilizing the thermal energy stored in the thermal energy storage system during the compressed air release process; A turbine generator is used to generate electricity when compressed air is released.

3. A compressed air energy storage device based on an aquifer according to claim 2, characterized in that: The underground aquifer consists of an aquifer and an injection / production well, the injection / production well being drilled into the aquifer; Aquifers, used as storage spaces for compressed air; Injection / production wells, used for injection and release of compressed air.

4. A compressed air energy storage device based on an aquifer according to claim 3, characterized in that: It also includes a first pipeline system, which connects the blower, the compressor, the cooling system and the injection / production well in sequence to complete the injection and storage process of compressed air.

5. The compressed air energy storage device based on an aquifer according to claim 3, characterized in that: It also includes a second pipeline system, which is connected in sequence to the injection / production well, the heating system and the turbine generator to complete the compressed air release production process.

6. The compressed air energy storage device based on an aquifer according to claim 3, characterized in that: It also includes a first gas cut-off valve and a second gas cut-off valve. The first gas cut-off valve is installed between the cooling system and the injection / production well, and the second gas cut-off valve is installed between the injection / production well and the heating system.

7. The compressed air energy storage device based on an aquifer according to claim 3, characterized in that: The selection conditions of aquifers are: permeability 1000-5000mD, depth 400-1200m, thickness 6-40m, and inclination greater than 1:

50.

8. The compressed air energy storage device based on an aquifer according to claim 2, characterized in that: The compressor uses a multi-stage compression method to gradually increase the air pressure, and the air is cooled through a cooling system after each stage of compression.

9. The compressed air energy storage device based on an aquifer according to claim 3, characterized in that: The air injection pressure of the injection / production wells shall not exceed 150% of the initial pore pressure and the air extraction pressure shall be above 75% of the initial pressure.

10. A method for operating a compressed air energy storage device based on an aquifer, characterized in that: The following steps are involved: During periods of low electricity prices or low grid load, excess energy is used to drive the blower to inhale air, which is then compressed by the compressor. The compressed air is cooled by the cooling system and the released heat energy is transferred to the thermal energy storage system. The cooled compressed air is injected into the aquifer through the injection / production well. The compressed air pushes the water in the aquifer to an area far away from the wellbore, forming air cushion bubbles, and the pressure in the aquifer gradually tends to balance. When the grid load is high or the demand increases, compressed air is drawn from the aquifer through the injection / production wells and enters the heating system. The heating system uses the thermal energy in the thermal energy storage system to heat the compressed air. The heated air expands in the turbine generator and drives the blades to rotate, driving the turbine generator to generate electricity. When the air in the aquifer is released, the air will be compressed by the blower, compressor and cooling system to store energy during the next low electricity consumption period, and then the heating system and turbine generator will release the air to generate electricity.

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