Carbon sequestration pumped hydro storage system and method of operation thereof

Abstract

The application provides a carbon sequestration pumped storage system and an operation method thereof, wherein the pumped storage system comprises a CO2 compression energy storage unit and a liquid storage working unit; the CO2 compression energy storage unit comprises a CO2 compression assembly and at least two gas storage tanks; the liquid storage working unit comprises a potential energy working assembly and a CO2 power generation working assembly which work by inputting gas CO2; the potential energy working assembly comprises an upstream reservoir, an upstream liquid storage well, a water turbine generator, a downstream pressure regulating well and a downstream reservoir which are sequentially arranged according to the circulation flow direction of a working fluid liquid; the CO2 power generation working assembly comprises a supercritical CO2 circulating generator; the upstream liquid storage well comprises a gas chamber which is communicated with the gas storage tank; the input end of the supercritical CO2 circulating generator is communicated with CO2 in a supercritical state, and the output end of the supercritical CO2 circulating generator is connected with the CO2 compression assembly.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a carbon-fixing pumped hydro storage system and its operation method. Background Technology

[0002] With increasing focus on sustainable and green development, new energy power generation is playing a vital role in the power industry, while the proportion of thermal power will gradually decrease. Reducing carbon emissions has become a key issue in power construction. However, new energy power generation suffers from drawbacks such as unstable power generation and asynchronous power consumption, while thermal power plays a crucial role in the power grid, serving functions such as peak shaving, frequency regulation, emergency backup, and load backup. With the vigorous development of the energy storage industry, electricity can be stored in stages, addressing the issue of asynchronous power generation and consumption after grid connection. Currently, the main energy storage methods for large-scale grid peak shaving and frequency regulation are pumped hydro storage, electrochemical energy storage, and hydrogen energy storage. However, all three have limitations. Pumped hydro storage requires specific terrain conditions, making it difficult to meet the needs of power generation at different scales; electrochemical energy storage is not suitable for grid-based peak shaving and frequency regulation; and hydrogen energy storage carries certain safety risks and is difficult to operate continuously. Furthermore, while these three energy storage methods are clean, they have not had a beneficial impact on energy conservation and emission reduction. Carbon sequestration refers to measures that increase the carbon content of carbon sinks other than the atmosphere. Applying this to power construction can effectively reduce environmental carbon emissions during power generation, achieving the goal of energy conservation and emission reduction. Therefore, the development of new pumped storage systems with carbon sequestration capabilities has broad prospects. While saving energy and reducing emissions, effective solutions can be adopted to improve the overall energy utilization efficiency and stability of the system, and distributed energy supply solutions can be combined to achieve more flexible power grid peak shaving and frequency regulation.

[0003] CN112796981A discloses a non-combustion CO2 energy storage system and method with high-efficiency thermal storage performance, including a compression system, a gas storage system, a thermal storage system, a pressure stabilization system, and a turbine system. In CO2 combustion, the heat generated during the CO2 combustion process is stored through the thermal storage system. When using CO2 to generate electricity, the air is heated through a heat transfer medium, improving power generation efficiency. Although this related technology effectively utilizes the heat generated during the CO2 combustion process for power generation, reducing energy loss and improving power generation efficiency, it suffers from a single form of heat utilization. Simply using CO2 to generate heat is insufficient to meet the heating needs of the thermal storage system, resulting in low feasibility. CN103114564A discloses a virtual pumped-storage power station and energy storage power generation method based on CO2 energy storage. It uses pumped-storage technology to achieve CO2 energy storage and power generation control, integrating multiple energy storage forms. However, it does not fully utilize the energy in CO2, and there is energy dissipation during the conversion of CO2 with water energy. Furthermore, this application lacks stable control of water pressure, making it difficult to maintain optimal power generation efficiency. Furthermore, this method lacks integration of multiple energy storage forms and distributed energy supply modes, making it difficult to adapt to the flexible peak-shaving and frequency regulation needs of the power grid. Related technology CN114709849A discloses a hydrogen energy storage and pumped storage coupled power station system and its operating method, including a power station, power grid, dispatch system, hydrogen storage system, and pumped storage system. This scheme achieves coordination between power generation, pumped storage, and hydrogen energy storage through reasonable power allocation. However, converting electrical energy into hydrogen energy storage through a pumped storage power station does not fundamentally change the power station's operating mode. It is significantly limited by terrain and topography, and the regulation of the power generation process is not flexible enough to support the need for high-efficiency power generation. It also does not have a beneficial impact on energy conservation and emission reduction. Moreover, compared to compressed carbon dioxide energy storage, hydrogen energy storage has disadvantages such as poor safety and limited applications. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in related technologies. It proposes a carbon-fixing pumped-storage system and its operation method. The system primarily utilizes a liquid storage unit for power generation, improving efficiency and stability. A CO2 compression storage unit provides supplementary synchronous power generation, increasing the power output per unit time. This electricity is supplied to the system itself. When the CO2 compression storage unit and the liquid storage unit generate power together, CO2 circulates continuously without leakage, further increasing the power output per unit time. Furthermore, during the joint power generation of the CO2 compression storage unit and the liquid storage unit, temperature control and combined exhaust mechanisms enhance the head and pressure regulation efficiency of the turbine generator, achieving rapid control of the power generation process.

[0005] To achieve the above objectives, this application proposes a carbon-fixing pumped hydro storage system, comprising:

[0006] A CO2 compression energy storage unit includes a CO2 compression assembly and at least two gas storage tanks; the input and output ends of the at least two gas storage tanks are respectively connected to the CO2 compression assembly via CO2 compression pipelines; the CO2 compression assembly is used to compress gaseous CO2 and generate high-pressure CO2; the high-pressure CO2 enters a downstream liquid storage and work unit through a CO2 energy release pipeline; and

[0007] The liquid storage and power generation unit includes a potential energy power generation component that introduces CO2 gas to perform work and a CO2 power generation component; wherein the potential energy power generation component includes an upstream reservoir, an upstream liquid storage well, a hydro-generator, a downstream surge tank, and a downstream reservoir arranged sequentially according to the direction of liquid circulation; the CO2 power generation component includes a supercritical CO2 circulating generator; the upstream liquid storage well includes a gas chamber that is connected to the gas storage tank; the input end of the supercritical CO2 circulating generator is supplied with supercritical CO2, and its output end is connected to the CO2 compression component.

[0008] In some embodiments, the CO2 compression energy storage unit further includes a CO2 liquid storage component, which is connected to the output end of the gas storage tank via a CO2 energy release pipeline; the CO2 liquid storage component includes a gas-liquid separator and a liquid chamber; wherein the input end of the gas-liquid separator is connected to the gas storage tank, its liquid output end is connected to the liquid chamber, and its gas output end is connected to the potential energy work component.

[0009] In some embodiments, a heat exchange unit is further included, which is connected to the CO2 compression assembly and the liquid storage work unit for heat exchange, and is used to store the compression heat generated by the CO2 compression assembly and provide heat to the liquid storage work unit.

[0010] In some embodiments, the heat exchange unit includes a heat storage device storing a heat exchange medium and a multi-stage interstage heat exchanger connected to the heat storage device; the CO2 compression assembly includes a multi-stage compressor, wherein the multi-stage interstage heat exchangers are arranged correspondingly to the multi-stage compressor, and the heat exchange medium in the heat storage device is introduced into the interstage heat exchangers to exchange heat with the high-pressure CO2 output by the multi-stage compressor and then flows back into the heat storage device.

[0011] In some embodiments, the heat exchange unit further includes a first heat exchanger and a third heat exchanger; the input and output ends of the hot side of the first heat exchanger and the third heat exchanger are respectively connected to the output and input ends of the heat storage device; the input end of the cold side of the first heat exchanger is connected to the gas storage tank, and its output end of the cold side is connected to the gas chamber; the input end of the cold side of the third heat exchanger is connected to the gas chamber, and its output end of the cold side is connected to the gas storage tank.

[0012] In some embodiments, at least two of the gas storage tanks are each provided with a corresponding self-heating device for cooling or heating the high-pressure CO2 stored in the gas storage tank using a medium at ambient temperature.

[0013] In some embodiments, the heat exchange unit further includes a second heat exchanger; the input and output ends of the hot side of the second heat exchanger are respectively connected to the output and input ends of the heat storage device; the input and output ends of the cold side of the second heat exchanger are both connected to the liquid chamber to maintain the temperature of the liquid CO2 in the liquid chamber.

[0014] In some embodiments, the output end of the gas chamber is connected to the input end of the gas storage tank via a return gas pipeline, and the return gas pipeline is connected to the liquid chamber; a pressure regulating device is provided in the liquid chamber, the return gas pipeline, and the connecting pipeline between the return gas pipeline and the liquid chamber.

[0015] In some embodiments, the CO2 compression assembly further includes an injection device; wherein the injection device is connected in parallel to the CO2 compression pipeline via a bypass pipe; wherein the CO2 finally output from the interstage heat exchanger is input to the gas storage tank via the CO2 compression pipeline and the injection device respectively.

[0016] In some embodiments, the pumped storage system further includes an energy control unit and a new energy power unit, wherein the new energy power unit, the liquid storage work unit, and the CO2 compression energy storage unit are all electrically connected to the energy control unit to realize energy regulation.

[0017] In some embodiments, an operation method for a carbon-fixing pumped-storage system is proposed, which generates electricity using the pumped-storage system described in any of the above embodiments, including the following process:

[0018] Energy storage stage: The high-pressure CO2 generated by the operation of the CO2 compression assembly is introduced into the multi-stage interstage heat exchanger and exchanges heat with the heat exchange medium in the heat storage device. The high-pressure CO2 is introduced into at least two gas storage tanks through the CO2 compression pipeline and the injection device, and at least one gas storage tank is filled with CO2. At the same time, the working fluid in the downstream reservoir is introduced into the upstream reservoir, and the working fluid in the downstream surge tank is kept at the specified level.

[0019] Power generation stage: including first power generation condition and second power generation condition; high-pressure CO2 is output from the gas storage tank and gas-liquid separation is performed, outputting liquid CO2 and gaseous CO2; gaseous CO2 enters the gas chamber after heat exchange with the heat exchange medium in the heat storage device, and the working liquid in the upstream liquid storage well enters the hydro-generator to generate electricity. The pressure of CO2 in the gas chamber and the liquid level of the working liquid in the liquid chamber are used to adjust the hydro-generator to keep it in the optimal operating condition.

[0020] In the second power generation condition, supercritical CO2 enters the supercritical CO2 cycle generator to generate electricity.

[0021] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0022] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is a schematic diagram of the structure of a carbon-fixing pumped storage system proposed in one embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the structure of a carbon-fixing pumped storage system proposed in one embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the structure of a carbon-fixing pumped storage system proposed in one embodiment of this application;

[0026] Figure 4 This is a schematic diagram of the structure of a carbon-fixing pumped storage system proposed in one embodiment of this application;

[0027] Figure 5 This is a flowchart of an operation method for a carbon-fixing pumped storage system according to an embodiment of this application.

[0028] In the diagram, 1 is the injection device; 2 is the second gas storage tank; 3 is the first gas storage tank; 4 (6, 7, 13) is the pressure regulating device; 5 (8, 31) is the flow control valve; 9 is the second heat exchanger; 10 is the supercritical CO2 circulating generator; 11 is the downstream pressure regulating well; 12 is the downstream reservoir; 14 is the hydro-generator; 15 is the transformer; 16 is the CO2 compressor; 17 is the third heat exchanger; 18-20 are heat exchangers; 21-23 (38) are pressure control valves; 24 is the heat storage device; 25 is the gas-liquid separator; 26 is the first heat exchanger; 27 (28) is the self-heating device; 29 is the upstream liquid storage well; 30 is the upstream reservoir; 32 is the temperature control device; 33 is the liquid chamber; 34 is the CO2 separation device; and 35 is the high-pressure water pump. Detailed Implementation

[0029] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, the embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0030] See Figure 1 To achieve the above objectives, this application proposes a carbon-fixing pumped hydro storage system, comprising a CO2 compression energy storage unit and a liquid storage power unit. The CO2 compression energy storage unit includes a CO2 compression assembly and at least two gas storage tanks. The input and output ends of the at least two gas storage tanks are respectively connected to the CO2 compression assembly via CO2 compression pipelines. The CO2 compression assembly is used to compress gaseous CO2 and generate high-pressure CO2. The high-pressure CO2 enters the downstream liquid storage power unit through a CO2 energy release pipeline.

[0031] The CO2 compression unit includes a CO2 compression assembly and at least two or more gas storage tanks. In this embodiment, the CO2 compression assembly compresses air to generate high-pressure CO2, which is then stored in the gas storage tanks via a CO2 compression pipeline 2. The CO2 compression assembly can be understood as a multi-stage CO2 compressor 16 connected in series, which compresses gaseous CO2 stage by stage to generate high-pressure CO2. The gas outlet of the final stage CO2 compressor 16 is connected to at least two gas storage tanks. It should be noted that the total capacity of all gas storage tanks is greater than the total amount of high-pressure CO2 generated by the CO2 compression assembly; therefore, in this embodiment, at least one of the two gas storage tanks is filled with CO2. In embodiments including multiple gas storage tanks, the CO2 pressure in one tank is lower than that in the other tanks. Those skilled in the art will understand that a gas storage tank filled with CO2 is designated as a high-pressure tank, and a gas storage tank not filled with CO2 is designated as a low-pressure tank, based on the pressure in the tank.

[0032] Examples such as Figure 1 The CO2 compression unit shown includes a three-stage CO2 compressor 16 connected in series and two gas storage tanks. Each gas storage tank is equipped with a gas inlet and a gas outlet. In this embodiment, the two gas storage tanks are a first gas storage tank 3 and a second gas storage tank 2, wherein the first gas storage tank 3 is a high-pressure gas storage tank and the second gas storage tank 2 is a low-pressure gas storage tank. The gas inlets of both the first gas storage tank 3 and the second gas storage tank 2 are connected to the gas outlet of the CO2 compressor 16 for storing high-pressure CO2.

[0033] In this embodiment, the liquid storage and power generation unit includes a potential energy power generation component and a CO2 power generation component. Gas CO2 is introduced into both the potential energy power generation component and the CO2 power generation component to generate electricity. The potential energy power generation component circulates a working liquid that performs work. The potential energy power generation component includes, in the direction of working liquid circulation, an upstream reservoir 30, an upstream liquid storage well 29, a hydro-generator 14, a downstream surge tank 11, and a downstream reservoir 12, arranged sequentially. The upstream liquid storage well 29 includes a gas chamber that is connected to a gas storage tank to achieve mutual circulation of gas CO2.

[0034] For example, the working fluid circulates and flows in the upstream reservoir 30, the upstream storage well 29, the turbine generator 14, the downstream surge tank 11, and the downstream reservoir 12. Flow control valves 31(8) are installed between the upstream reservoir 30 and the upstream storage well 29, between the upstream storage wells 29, and between the turbine generator 14, the downstream surge tank 11, and the downstream reservoir 12. A high-pressure water pump 35 is installed between the downstream reservoir 12 and the upstream reservoir 30. In this embodiment, the flow control valves 31(8) control the generator head of the turbine generator 14, maintaining the generator head at the optimal power generation efficiency of the turbine and improving the power generation efficiency. In this embodiment, an air chamber is provided in the upstream storage well 29, which is used to fill with CO2 gas. It is understood that the CO2 gas in the air chamber can be isolated from or not isolated from the working fluid liquid with a certain liquid level in the upstream storage well 29. In this embodiment, the air chamber includes an input end and an output end, both of which are connected to a gas storage tank, enabling the CO2 in the air chamber and the gas storage tank to flow between each other. In this embodiment, a closed upstream storage well 29 is used instead of a surge tank in related technologies. In related technologies, pumped storage technology uses surge tanks to control the head of the turbine generator 14. The head of the turbine generator 14 has an upper limit and is greatly affected by terrain. In this embodiment, the closed upstream storage well 29 allows for free adjustment of the head, adapting to the efficient power generation of different turbine generator sets 14.

[0035] Examples such as Figure 1 As shown, the input end of the gas chamber is connected to the first gas storage tank 3 via a CO2 energy release pipeline. A pressure regulating device 6 is installed on the CO2 energy release pipeline between the gas chamber and the first gas storage tank 3. Gas CO2 is introduced into the gas chamber, and the gas CO2 exerts pressure on the working liquid in the upstream storage well 29. The working liquid in the upstream storage well 29 enters the hydro-generator 14 through the flow control valve 8 to generate electricity. The power generation tail fluid output from the hydro-generator 14 enters the downstream pressure regulating well 11. The working head of the hydro-generator 14 is regulated by the liquid level of the working liquid in the upstream storage well 29, the capacity of the gas CO2 in the gas chamber, and the liquid level of the working liquid in the downstream pressure regulating well 11, so that the hydro-generator 14 is kept in the optimal operating condition.

[0036] In this embodiment, the CO2 power generation and power generation component includes a supercritical CO2 circulating generator 10. Supercritical CO2 is introduced into the input of the supercritical CO2 circulating generator 10, and its output is connected to a CO2 compression component. The CO2 power generation and power generation component includes the supercritical CO2 circulating generator 10, in which supercritical CO2 is introduced to generate electricity. The generated CO2 is then integrated by a CO2 separation device 34 and recycled back to the CO2 compression component for further compression and recycling. The supercritical CO2 control principle is used to prevent CO2 liquefaction, improving the flexibility of CO2 utilization. The known supercritical temperature of CO2 is 31.2℃; above this temperature, arbitrary pressurization will not cause liquefaction.

[0037] Therefore, in this embodiment, the CO2 compression energy storage unit generates high-pressure CO2, which is then stored in a gas storage tank. Simultaneously, surplus electrical energy is used by the liquid storage unit to pump water from the downstream reservoir 12 to the upstream reservoir 30 for storage. Since the upstream reservoir 30 is connected to the upstream liquid storage well 29, a certain level of working fluid can be stored in the upstream liquid storage well 29. After energy storage, the high-pressure gas storage tank is connected to the upstream liquid storage well 29 to form a high-head water body. A pressure controller can be installed at the liquid output end of the upstream liquid storage well 29 to maintain a constant pressure of the output working fluid, ensuring that the turbine generator 14 remains in optimal operating condition. When power generation or energy supply is required, high-pressure CO2 is input into the gas chamber, driving the working fluid in the upstream liquid storage well 29 through the turbine generator 14 to generate electricity. A temperature control device 32 is installed here to prevent the high-pressure CO2 from liquefying. The tailwater from the turbine generator 14 is discharged into the downstream surge tank 11 for storage, reducing the CO2 pressure and preventing the waste of energy from the high-pressure CO2. In addition, during the power generation or energy supply stage, high-pressure CO2 can be directly used to generate electricity through the supercritical CO2 cycle generator 10. The electrical energy generated by the supercritical CO2 cycle generator 10 is limited by the gas capacity and is relatively small. Therefore, it can be directly supplied to the electrical components in the pumped storage system that can fix carbon, without being connected to the power grid.

[0038] This application primarily utilizes a liquid storage power generation unit to improve power generation efficiency and stability. A CO2 compression energy storage unit, acting as a supplementary synchronous power generation unit, increases the power generation per unit time. This portion of the electricity is supplied to the system itself. When the CO2 compression energy storage unit and the liquid storage power generation unit work together, CO2 circulates continuously without leakage, further increasing the power generation per unit time. Therefore, this application utilizes the high-concentration CO2 gas generated from fossil fuel power generation, employing an existing supercritical CO2 circulating generator 10 to generate electricity. The gasification and liquefaction states of CO2 are adjusted according to demand. Excess supercritical CO2 can be used to produce refrigerants, fire extinguishing agents, etc., achieving carbon sequestration and making the process cleaner and more environmentally friendly.

[0039] In some embodiments, the CO2 compression energy storage unit further includes a CO2 liquid storage component, which is connected to the output end of the gas storage tank via a CO2 energy release pipeline, and includes a gas-liquid separator 25 and a liquid chamber 33; wherein the input end of the gas-liquid separator 25 is connected to the gas storage tank, its liquid output end is connected to the liquid chamber 33, and its gas output end is connected to the potential energy power generation component. The CO2 liquid storage component includes a gas-liquid separator 25 and a liquid chamber 33, wherein the input end of the gas-liquid separator 25 is connected to the output end of the gas storage tank via a CO2 energy release pipeline, that is, the gas-liquid separator 25 separates the input mixed CO2 into liquid and gas, wherein the liquid CO2 enters the liquid chamber 33 for storage, and the gaseous CO2 enters the potential energy power generation component after being pressurized and heated by the pressure regulating device 6 via the CO2 energy release pipeline; the liquid CO2 stored in the liquid chamber 33 can be adjusted in temperature and pressure to become supercritical before entering the CO2 power generation component to generate electricity.

[0040] In some embodiments, the pumped hydro storage system further includes a heat exchange unit connected to both the CO2 compression assembly and the liquid storage working unit. The heat exchange unit stores the heat generated by the CO2 compression assembly and provides heat to the liquid storage working unit. For example, both the CO2 compression assembly and the liquid storage working unit experience heat loss during operation. This application utilizes the heat exchange unit to recover the heat generated by the CO2 compression assembly during operation and releases the recovered heat during the operation of the liquid storage working unit, aiming to achieve better power generation performance.

[0041] In some embodiments, the heat exchange unit includes a heat storage device 24 storing a heat exchange medium and a multi-stage interstage heat exchanger connected to the heat storage device 24; the CO2 compression assembly includes a multi-stage compressor, wherein the multi-stage interstage heat exchanger is correspondingly arranged with the multi-stage compressor, and the heat exchange medium in the heat storage device 24 is introduced into the interstage heat exchanger to exchange heat with the high-pressure CO2 output by the multi-stage compressor and then flows back into the heat storage device 24.

[0042] The heat exchange unit includes a heat storage device 24 storing the heat exchange medium and a multi-stage interstage heat exchanger. The number of multi-stage interstage heat exchangers matches the number of multi-stage compressors in the embodiment, meaning the multi-stage interstage heat exchangers are correspondingly set to the multi-stage compressors. Each multi-stage interstage heat exchanger includes a hot side and a cold side. The cold side of the multi-stage interstage heat exchanger is fed with a low-temperature heat exchange medium from the heat storage device 24 for heat exchange with the high-pressure CO2 output from the compressor fed to the hot side of the multi-stage interstage heat exchanger. The heat exchange medium in the heat storage device 24 is fed into the interstage heat exchanger, exchanges heat with CO2, and then flows back into the heat storage device 24. The high-pressure CO2 after heat exchange enters the gas storage tank. In this embodiment, the heat storage device 24 can integrate electricity and solar energy, meaning that it can heat the heat exchange medium when electricity and solar energy are input. This non-combustion method reduces environmental pollution and is more environmentally friendly.

[0043] For example, such as Figure 2 The multi-stage interstage heat exchanger shown includes three heat exchangers 18 (19, 20) that exchange heat with the CO2 output from the three-stage CO2 compressor 16 connected in series. Specifically, a cold heat exchange medium input from the heat storage device 24 is introduced into the cold side of each heat exchanger 18 (19, 20), while high-pressure CO2 output from the three-stage CO2 compressor 16 is introduced into the hot side of each heat exchanger for heat exchange. The heat exchange medium after heat exchange flows back to the heat storage device 24, while the high-pressure CO2 output from the final stage compressor 16 enters the gas storage tank after heat exchange. Therefore, in this embodiment, the heat storage device 24 and the multi-stage interstage heat exchanger are used to recover a large amount of heat generated during the CO2 compression process of the CO2 compression assembly.

[0044] In some embodiments, the heat exchange unit further includes a first heat exchanger 26; the hot side input and output of the first heat exchanger 26 are respectively connected to the output and input of the heat storage device 24; the cold side input of the first heat exchanger 26 is connected to a gas storage tank, and its cold side output is connected to a gas chamber such as... Figure 2 As shown. In some embodiments, the heat exchange unit further includes a third heat exchanger 17, the hot side of which is connected to the output and output of the heat storage device 24, respectively; the cold side of the third heat exchanger 17 is connected to the gas chamber, and its cold side is connected to the gas storage tank.

[0045] Examples such as Figure 3As shown, the heat exchange unit also includes a first heat exchanger 26 and a third heat exchanger 17, both of which have the same heat exchange structure, i.e., both include a hot side and a cold side. The input and output ends of the hot side of the first heat exchanger 26 are connected to the output and input ends of the heat storage device 24, respectively. The input end of the cold side of the first heat exchanger 26 is connected to the gas storage tank, and its output end is connected to the gas chamber. Furthermore, a pressure regulating device is installed between the input end of the cold side of the first heat exchanger 26 and the gas storage tank, and another pressure regulating device 13 is installed on the connecting pipeline between the output end of the cold side of the first heat exchanger 26 and the gas chamber. In this embodiment, the input end of the cold side of the third heat exchanger 17 is connected to the gas chamber, and according to the flow direction of the CO2 gas, the pressure regulating device 4 is located upstream of the input end of the cold side of the third heat exchanger 17; the output end of the cold side of the third heat exchanger 17 is connected to the gas storage tank. In this embodiment, the CO2 gas separated and output by the gas-liquid separator 25 is pressurized and heated by the pressure regulating device 6 through the CO2 energy release pipeline, and then enters the cold side of the first heat exchanger 26 to exchange heat with the heat exchange medium of the heat storage device 24 entering the hot side of the first heat exchanger 26. The heated CO2 gas enters the gas chamber; the cooled heat exchange medium enters the heat storage device 24. During the process of adjusting the work of the hydro-generator 14, the CO2 released when the upstream liquid storage well 29 depressurizes can be pressurized through the pipeline and another pressure regulating device 4 installed on the pipeline, and then enters the cold side of the third heat exchanger 17, where it exchanges heat with the heat exchange medium of the heat storage device 24 entering the hot side of the third heat exchanger 17. The CO2 after heat exchange enters the second gas storage tank 2; the cooled heat exchange medium enters the heat storage device 24. This application utilizes a thermal storage device 24 to heat CO2, achieving temperature control and constantly monitoring the supercritical state of CO2. Leveraging the supercritical characteristics of CO2, the application controls the vaporization and liquefaction of CO2 by adjusting temperature and pressure, adapting to different applications. The heat exchange medium in the thermal storage device 24 raises the temperature of the high-pressure CO2 power generation, thereby increasing the power generation efficiency of the gaseous CO2. The supercritical CO2 stored in the liquid chamber 3333 can enter the CO2 power generation assembly to generate electricity. The CO2 output from the supercritical CO2 cycle generator 10 is then compressed and circulated again in the CO2 compressor 16.

[0046] In some embodiments, at least two gas storage tanks are each provided with a corresponding self-heating device 27 (28) for cooling or heating the high-pressure CO2 stored in the gas storage tank using a medium at ambient temperature.

[0047] Each of the gas storage tanks is equipped with its own corresponding self-heating device 27 (28). The self-heating device is a component containing a medium with ambient temperature. It absorbs the heat of CO2 in the gas storage tank using the medium with ambient temperature, and then releases the absorbed heat into the CO2 in the gas storage tank at an appropriate time, thereby achieving the effect of regulating the temperature of CO2 in the gas storage tank. It is used to cool or heat CO2 in different states stored in the gas storage tank using a medium with ambient temperature.

[0048] In some embodiments, the heat exchange unit further includes a second heat exchanger 9; the input and output ends of the hot side of the second heat exchanger 9 are respectively connected to the output and input ends of the heat storage device; the input and output ends of the cold side of the second heat exchanger 9 are both connected to the liquid chamber 33. In this embodiment, liquid CO2 is introduced into the input end of the cold side of the second heat exchanger 9; heat exchange occurs with the heat exchange medium introduced into the hot side of the second heat exchanger 9 by the heat storage device 24, and the heated liquid CO2 flows back into the liquid chamber 33 to maintain the temperature of the liquid CO2 in the liquid chamber 33 above 31.2 degrees Celsius but not exceeding the conventional temperature of supercritical CO2; the cooled heat exchange medium is introduced into the heat storage device 24, thereby increasing the power generation of the supercritical CO2 cycle generator.

[0049] As can be seen, in order to prevent the liquefaction of gaseous CO2 in this embodiment, all pipelines transporting CO2 need to be specially designed and adopt a double-layer structure. The outer layer flows with a high-temperature heat-conducting medium, and the inner layer flows with CO2 gas, maintaining the CO2 gas temperature above the supercritical temperature of 31.2 degrees Celsius.

[0050] In some embodiments, the output end of the gas chamber is connected to the input end of the gas storage tank through a return gas pipeline, and the return gas pipeline is connected to the liquid chamber 33; a pressure regulating device is provided on the liquid chamber 33, the return gas pipeline, and the connecting pipeline between the return gas pipeline and the liquid chamber 33.

[0051] The output end of the gas chamber is connected to the input end of the gas storage tank via a return gas pipeline; the return gas pipeline is connected to the input end of the liquid chamber 33. It can be seen that during the process of regulating the work done by the hydro-generator 14, the upstream liquid storage well 29 releases CO2 gas when the pressure is reduced. Part of the CO2 gas released from the gas chamber is regulated by a pressure regulating device 7 and then enters the liquid chamber 33, while the other part of the CO2 is regulated by a pressure regulating device 4 on the return gas pipeline and then enters the second gas storage tank 2.

[0052] Examples such as Figure 1As shown, the input end of the gas chamber is connected to the first gas storage tank 3, and its output end is connected to the second gas storage tank 2. Pressure regulating devices 6 (4) are installed on the connecting pipes between the gas chamber and the first and second gas storage tanks 3 and 2. In this embodiment, CO2 from the first gas storage tank 3 can be used to fill the gas chamber, and a portion of the recovered CO2 output from the gas chamber is passed through the return gas pipeline and, after being regulated by the pressure regulating device 4, enters the cold side of the third heat exchanger 17 and exchanges heat with the heat exchange medium. The CO2 after heat exchange enters the second gas storage tank 2. Another portion of the recovered CO2 output from the gas chamber is regulated by the pressure regulating device 7 on the pipeline and then passed into the liquid chamber 33 to achieve CO2 recovery and utilization. The liquid chamber 33 is equipped with a pressure control device to maintain the pressure of the liquid CO2 within it at a supercritical pressure of 7.38 MPa or higher. The second heat exchanger 9 maintains the temperature of the liquid CO2 at a supercritical state of 31.2 degrees Celsius or higher.

[0053] Compared to related technologies that use temperature control or exhaust measures alone to regulate the pressure in a water-gas co-containment chamber, which is slow and inefficient, and uses fossil fuels to generate steam for heating, causing environmental pollution, this embodiment uses a combination of temperature control and exhaust to improve pressure regulation efficiency. In addition, the CO2 recovered from the gas chamber is not directly discharged, but is stored again in a low-pressure gas storage tank to improve energy utilization.

[0054] In some embodiments, the CO2 compression assembly further includes an injection device 1; wherein the injection device 1 is connected in parallel to the CO2 compression pipeline 2 via a bypass pipe; wherein after heat exchange in the first heat exchanger 26, CO2 is input to the gas storage tank via the CO2 compression pipeline 2 and the injection device 1 respectively.

[0055] Examples such as Figure 4 As shown, the CO2 compression assembly also includes an injection device 1, wherein a bypass pipe is connected in parallel to the CO2 compression pipeline 2. Both the input and output ends of the bypass pipe are connected to the CO2 compression pipeline 2. Based on the flow path of CO2 in the CO2 compression pipeline 2, the input end of the bypass pipe is located downstream of the CO2 compression assembly, meaning that after heat exchange in the first heat exchanger 26, CO2 passes through both the CO2 compression pipeline 2 and the bypass pipe. The output end of the bypass pipe is located upstream of the gas storage tank. In this application, the injection device 1 is used to regulate the output flow rate of CO2, maintaining the output flow rate and pressure of CO2 at the optimal compression efficiency state of the CO2 compressor, thereby improving the compression efficiency of CO2. It is known that pressure control valves 38 (21-23) are installed on the CO2 compression pipeline 2, the bypass pipe, and the connecting pipe to the gas storage tank. The pressure control valves 38 (21-23) regulate the CO2 compression pressure, and the injection device 1 regulates the CO2 compression flow rate, maintaining the flow rate and pressure at the optimal compression efficiency state of the CO2 compressor 16, thereby improving the compression efficiency of high-pressure CO2.

[0056] In some embodiments, the system further includes an energy control unit and a new energy power unit, wherein the output power of the new energy power unit, the liquid storage power unit, and the CO2 compression energy storage unit is connected to the grid through the energy control unit.

[0057] For example, the energy storage system also includes a control unit and a new energy power unit, which are connected to the control unit. The new energy power unit includes wind power and other new energy power generation forms. In this embodiment, the power generated by wind power generation, as well as the power generated by the hydro generator 14 and the turbine, enters the control unit after passing through the transformer 15. The control unit regulates and connects the generated power to the grid. The control unit can regulate the amount of power generated by this system that is connected to the grid, and supply power to various energy-consuming components in the energy storage system such as pumps, cooling components, CO2 compressor 16, and electric heaters. Therefore, this embodiment has advantages such as no additional combustion, clean and environmentally friendly, high efficiency, distributed power supply, multi-energy storage, and high energy utilization. It can distribute and allocate solar energy, wind power generation, CO2 compression energy storage unit power generation, and liquid storage power generation, and the power generation of the liquid storage unit. The combined power generation can increase the power generation per unit time. The excess power is connected to the grid, and some power is used by the system itself. It also takes into account the energy required for heating and dynamically allocates the power, improves the flexibility of energy supply, and further improves the energy conversion rate.

[0058] In some embodiments, according to the second aspect of this application, a method for energy storage of a carbon-fixable pumped-storage system is provided, which generates electricity using the pumped-storage system in any of the above embodiments, including the following processes: Figure 5 As shown:

[0059] Energy storage stage: The high-pressure CO2 generated by the operation of the CO2 compression assembly is introduced into the multi-stage interstage heat exchanger and exchanges heat with the heat exchange medium in the heat storage device 24. The high-pressure CO2 is then introduced into at least two gas storage tanks through the CO2 compression pipeline and the injection device 1, and at least one gas storage tank is filled with CO2. At the same time, the working liquid in the downstream reservoir 12 is introduced into the upstream reservoir 30, and the working liquid in the downstream surge tank 11 is kept at the specified level.

[0060] Power generation stage: including first power generation condition and second power generation condition; high-pressure CO2 is output from the gas storage tank and gas-liquid separation is performed, outputting liquid CO2 and gaseous CO2; gaseous CO2 enters the gas chamber after heat exchange with the heat exchange medium in the heat storage device, and the working liquid in the upstream liquid storage well 29 enters the hydro turbine generator 14 to generate electricity. The CO2 pressure in the gas chamber and the liquid level of the working liquid in the liquid chamber 33 are used to adjust the hydro turbine generator 14 to maintain the optimal operating condition; in the second power generation condition, supercritical CO2 enters the supercritical CO2 cycle generator 10 to generate electricity.

[0061] Specifically, the energy control unit uses off-peak electricity and new energy power to drive the CO2 compression assembly to compress CO2 gas. Heat exchange between the high-pressure CO2 and the low-temperature heat exchange medium is achieved through the interstage heat exchanger in the CO2 compression assembly, and the heat exchange medium flows into the heat storage device 24. The high-pressure CO2 after heat exchange is input into at least two gas storage tanks through the CO2 compression pipeline and the injection device 1, with at least one gas storage tank filled with CO2. Simultaneously, the working fluid in the downstream reservoir 12 is input into the upstream reservoir 30. Through the adjustment of the flow control valve 31 between the upstream reservoir 30 and the upstream storage well 29, the working fluid in the upstream reservoir 30 is circulated into the upstream storage well 29, while maintaining the working fluid in the downstream pressure regulating well 11 at a specified level.

[0062] The power generation stage includes a first power generation condition and a second power generation condition. High-pressure CO2 is output from the first gas storage tank 3 and undergoes gas-liquid separation. The output liquid CO2 is stored in the liquid chamber 33 and becomes supercritical CO2. The output gaseous CO2 enters the CO2 energy release pipeline and is pressurized and heated by the pressure regulating device 6 before being introduced into the cold side of the first heat exchanger 26. It exchanges heat with the heat exchange medium from the heat storage device 24, which is then introduced into the hot side of the first heat exchanger 26. The heated gaseous CO2 enters the gas chamber. The cooled heat exchange medium is then introduced into the heat storage device 24. During the adjustment of the power output of the hydro-generator 14, CO2 released when the upstream liquid storage well 29 depressurizes can enter the liquid chamber 33 after being pressurized by a pipeline and another pressure regulating device 7 installed on the pipeline. Alternatively, CO2 released when the upstream liquid storage well 29 depressurizes can enter the cold side of the third heat exchanger 17 through the return gas pipeline, exchange heat with the heat exchange medium on the hot side of the first heat exchanger 26, and then enter the second gas storage tank 2.

[0063] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0064] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0065] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0066] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A pumped-storage system capable of carbon fixation, characterized in that, include CO2 compression energy storage unit, which includes a CO2 compression assembly and at least two gas storage tanks; At least two of the gas storage tanks have their input and output ends connected to the CO2 compression assembly via CO2 compression pipelines; the CO2 compression assembly compresses gaseous CO2 and generates high-pressure CO2; the high-pressure CO2 enters the downstream liquid storage unit via a CO2 energy release pipeline; the CO2 compression energy storage unit further includes a CO2 liquid storage assembly, which is connected to the output end of the gas storage tank via a CO2 energy release pipeline; the CO2 liquid storage assembly includes a gas-liquid separator and a liquid chamber; wherein the input end of the gas-liquid separator is connected to the gas storage tank, its liquid output end is connected to the liquid chamber, and its gas output end is connected to the potential energy work assembly; and The liquid storage and power generation unit includes a potential energy power generation component that performs work by introducing CO2 gas and a CO2 power generation component. The potential energy power generation component comprises an upstream reservoir, an upstream liquid storage well, a hydro-generator, a downstream pressure regulating well, and a downstream reservoir arranged sequentially according to the working fluid circulation direction. The CO2 power generation component includes a supercritical CO2 circulating generator. A temperature control device is installed in the upstream liquid storage well, which includes a gas chamber connected to the gas storage tank. The output end of the gas chamber is connected to the input end of the gas storage tank via a return gas pipeline, which is connected to the liquid chamber. Pressure regulating devices are installed in the liquid chamber, on the return gas pipeline, and on the connecting pipeline between the return gas pipeline and the liquid chamber. The input end of the supercritical CO2 circulating generator is supplied with supercritical CO2, and its output end is connected to the CO2 compression component. A heat exchange unit is connected to both the CO2 compression assembly and the liquid storage work unit for heat exchange. It stores the compression heat generated by the CO2 compression assembly and provides heat to the liquid storage work unit. The heat exchange unit includes a heat storage device containing a heat exchange medium and a multi-stage interstage heat exchanger connected to the heat storage device. The CO2 compression assembly includes a multi-stage compressor, with the multi-stage interstage heat exchangers corresponding to the multi-stage compressor. The heat exchange medium in the heat storage device flows into the interstage heat exchangers to exchange heat with the high-pressure CO2 output from the multi-stage compressor and then flows back into the heat storage device. The heat exchange unit also includes a second heat exchanger. The hot side input and output of the second heat exchanger are connected to the output and input of the heat storage device, respectively. The cold side input and output of the second heat exchanger are connected to the liquid chamber to maintain the temperature of the liquid CO2 in the liquid chamber.

2. The pumped storage system according to claim 1, characterized in that, The heat exchange unit further includes a first heat exchanger and a third heat exchanger; the input and output ends of the hot side of the first heat exchanger and the third heat exchanger are respectively connected to the output and input ends of the heat storage device; the input end of the cold side of the first heat exchanger is connected to the gas storage tank, and its output end of the cold side is connected to the gas chamber; the input end of the cold side of the third heat exchanger is connected to the gas chamber, and its output end of the cold side is connected to the gas storage tank.

3. The pumped storage system according to claim 1, characterized in that, At least two of the gas storage tanks are equipped with their respective self-heating devices, which use a medium at ambient temperature to cool or heat the high-pressure CO2 stored in the gas storage tanks.

4. The pumped storage system according to claim 1, characterized in that, The output end of the gas chamber is connected to the input end of the gas storage tank via a return gas pipeline, which is connected to the liquid chamber. Pressure regulating devices are provided in the liquid chamber, the return gas pipeline, and the connecting pipeline between the return gas pipeline and the liquid chamber.

5. The pumped storage system according to claim 1, characterized in that, The CO2 compression assembly also includes an injection device; The injection device is connected in parallel to the CO2 compression pipeline via a bypass pipe; the CO2 finally output from the interstage heat exchanger is input to the gas storage tank through the CO2 compression pipeline and the injection device.

6. The pumped storage system according to claim 1, characterized in that, It also includes an energy control unit and a new energy power unit, wherein the new energy power unit, the liquid storage power unit and the CO2 compression energy storage unit are all electrically connected to the energy control unit to realize power regulation.

7. A method for operating a carbon-fixing pumped-storage system, characterized in that, Power generation using the pumped storage system described in any one of claims 1-6 Includes the following processes: Energy storage stage: The high-pressure CO2 generated by the operation of the CO2 compression assembly is introduced into the multi-stage interstage heat exchanger and exchanges heat with the heat exchange medium in the heat storage device. The high-pressure CO2 is introduced into at least two gas storage tanks through the CO2 compression pipeline and the injection device, and at least one gas storage tank is filled with CO2. At the same time, the working fluid in the downstream reservoir is introduced into the upstream reservoir, and the working fluid in the downstream surge tank is kept at the specified level. Power generation stage: including first power generation condition and second power generation condition; high-pressure CO2 is output from the gas storage tank and gas-liquid separation is performed, outputting liquid CO2 and gaseous CO2; gaseous CO2 enters the gas chamber after heat exchange with the heat exchange medium in the heat storage device, and the working liquid in the upstream liquid storage well enters the hydro-generator to generate electricity. The pressure of CO2 in the gas chamber and the liquid level of the working liquid in the liquid chamber are used to adjust the hydro-generator to keep it in the optimal operating condition. In the second power generation condition, supercritical CO2 enters the supercritical CO2 cycle generator to generate electricity.

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