Solar power generation system coupled with compressed carbon dioxide energy storage

Abstract

The present invention belongs to the field of solar energy. To address the problems of complex structure, poor stability, and low energy utilization in solar power generation systems, the present invention provides a solar power generation system coupled with compressed carbon dioxide energy storage, including a solar supercritical carbon dioxide power generation system and a compressed carbon dioxide energy storage system; the solar supercritical carbon dioxide power generation system includes a heliostat field, a solar collector, a turbine expander, a generator, a precooler, a second valve, a compressor, a heat exchanger, a heat replenisher, a heat accumulator, a fourth valve, and a fifth valve; the compressed carbon dioxide energy storage system includes a first valve, a low-pressure gas storage tank, a high-pressure gas storage tank, and a third valve; and diversion is performed at the compressor outlet to convert excess solar energy into thermal energy for storage. The present invention allows excess solar energy during the day to be exported as electricity at night through the same supercritical carbon dioxide power generation system, thereby achieving a stable 24-hour output from the solar power generation system.

Description

Technical Field

[0001] The present invention belongs to the field of solar energy, and in particular relates to a solar power generation system coupled with compressed carbon dioxide energy storage. Background Art

[0002] Solar thermal power generation is a general term for power generation technologies that convert solar energy into thermal energy through specific technical means, then utilize a thermodynamic cycle to perform work, thereby generating electricity through a generator. It is a high-quality way to utilize solar energy. Currently, various thermodynamic cycles are used in solar power generation, among which the supercritical carbon dioxide (S-CO2) Brayton cycle offers several advantages. As the sole circulating fluid in this cycle, supercritical carbon dioxide has a low critical point (7.38 MPa, 304 K), making it easier to reach a supercritical state than other working fluids such as water, facilitating engineering applications. Supercritical carbon dioxide combines the properties of both liquids and gases, with high density, high heat transfer efficiency, strong work capacity, low viscosity, high fluidity, and low system cycle losses. Furthermore, within the entire power system, the cycle operates in a supercritical state, maintaining a dense working fluid, making the turbine expander and heat exchanger smaller than those required for traditional power cycles.

[0003] However, because solar radiation intensity fluctuates over time and due to factors such as weather, traditional solar thermal power generation systems often fail to reach their set output parameters during periods of poor weather or at night, impacting their normal operation. Therefore, reducing or even eliminating the impact of solar radiation intensity fluctuations on solar systems is a pressing issue in the field of solar thermal power generation. To address this need for technical improvements, researchers have proposed various solutions:

[0004] Solution 1: Patent application number CN201310743891.5 addresses the heat storage problem of solar thermal power generation systems and proposes a new solution based on molten salt heat storage: molten salt with a lower melting point is used as the heat absorbing working fluid of the solar system, and a binary salt is introduced as the working fluid of the heat storage system to provide heat to the system when solar radiation is insufficient.

[0005] Solution 2: The patent application with application number CN202120988320.8 proposes a molten salt heat storage peak-shaving system based on the different output power requirements of the turbine. When the required turbine output power is small, the molten salt is heated by high-temperature working fluid and stored in a hot tank. When the required output power is large, the molten salt heat storage is used to heat the working fluid to perform work, thereby achieving heat storage peak-shaving.

[0006] Solution 3: Patent application number CN201911169727.1 addresses the phenomenon of excess solar energy during the day. In order to fully utilize energy, it proposes a solution: coupling a compressed air energy storage system with a solar supercritical carbon dioxide Brayton cycle power generation system to fully utilize excess solar energy.

[0007] Solution 4: Patent application number CN201710243325.6 proposes a scheme for compressed supercritical carbon dioxide energy and heat storage in response to the changes in high and low loads of the power grid: electric energy is used to compress supercritical carbon dioxide during the low load period of the power grid, and the stored carbon dioxide is released during the peak load period to drive the turbine expander to do work, thereby achieving "peak shaving and valley filling".

[0008] These existing solutions have obvious problems in terms of system complexity, stability and power generation efficiency.

[0009] Option 1, which adds molten salt heat storage to a solar thermal power generation system, uses a single form of energy storage. To ensure normal operation when solar radiation is weak, additional pressurization equipment is required to increase the working fluid pressure. This results in increased energy consumption, reduced power generation efficiency, and poor economic performance.

[0010] The molten salt heat storage peak-shaving system proposed in Option 2 includes two molten salt heat storage systems, A and B. The system has too many components, which increases the complexity of the system, may increase the risk of system failure, and increase the system maintenance cost.

[0011] Option 3 proposes adding a compressed air energy storage system to store excess solar energy during the day. This method requires filling the system with two working fluids, carbon dioxide and air, which increases the system's operating and maintenance costs and increases the risk of working fluid leakage.

[0012] While the energy storage solution proposed in Option 4 achieves both heat and pressure storage, the high-temperature, high-pressure working fluid must first undergo heat release before being stored in the high-pressure gas tank. This results in a complex system structure and the need for more heat exchange equipment, which reduces system economics. Furthermore, since this solution uses thermal oil as the heat transfer medium, its temperature cannot be too high, resulting in reduced heat quality and cycle efficiency.

[0013] Therefore, it is necessary to study a solar power generation system with simple structure, good stability and high energy utilization rate. Summary of the Invention

[0014] To address the above issues, the present invention provides a solar power generation system coupled with compressed carbon dioxide energy storage. This system, based on a solar supercritical carbon dioxide Brayton cycle power generation system, adds an energy storage device to store excess daytime solar energy. The basic principle of this system is to divert the flow at the compressor outlet and store the high-pressure carbon dioxide in a high-pressure gas tank. Simultaneously, molten salt thermal storage is added to the solar energy system to convert excess solar energy into thermal energy for storage. This invention allows excess daytime solar energy to be exported at night through the same supercritical carbon dioxide power generation system, thereby achieving a stable 24-hour output from the solar power generation system.

[0015] The technical solutions of the present invention are as follows:

[0016] A solar power generation system coupled with compressed carbon dioxide energy storage, comprising a solar supercritical carbon dioxide power generation system and a coupled compressed carbon dioxide energy storage system;

[0017] The solar supercritical carbon dioxide power generation system includes a heliostat field, a solar collector, a turbine expander, a generator, a precooler, a second valve, a compressor, a heat exchanger, a supplementary heat device, a heat accumulator, a fourth valve, and a fifth valve;

[0018] The heliostat field is connected to a solar thermal collector, the solar thermal collector outlet is connected to a turbine expander inlet, and the turbine expander is connected to a generator; the turbine expander outlet is connected to a high-temperature side inlet of a heat exchanger, the high-temperature side outlet of the heat exchanger is connected to a precooler inlet, the precooler outlet is connected to a second valve and then to a compressor inlet, the compressor outlet is connected to a low-temperature side inlet of the heat exchanger, the low-temperature side outlet of the heat exchanger is divided into two paths, one path is connected to a fifth valve and then to a solar thermal collector inlet, and the other path is connected to a fourth valve and then to a heat accumulator inlet, the heat accumulator outlet is connected to a supplementary heat inlet, and the supplementary heat outlet is connected to the turbine expander inlet;

[0019] The compressed carbon dioxide energy storage system includes a first valve, a low-pressure gas storage tank, a high-pressure gas storage tank, and a third valve; the low-pressure gas storage tank is connected to the outlet of the precooler, and the first valve is provided on the connecting pipeline; the high-pressure gas storage tank is connected to the third valve and then connected to the pipeline between the outlet of the compressor and the inlet of the low-temperature side of the heat exchanger;

[0020] The working medium of the solar supercritical carbon dioxide power generation system and the compressed carbon dioxide energy storage system is both supercritical carbon dioxide.

[0021] When there is sufficient sunlight during the day, the first valve, the second valve, and the fifth valve are opened, and the third valve and the fourth valve are closed. The heat absorbed by the solar collector is used to heat the carbon dioxide fluid in the pipeline. After absorbing heat, the fluid performs work in the turbine expander, driving the turbine expander to rotate and generate electricity through the generator. The high-temperature, low-pressure supercritical carbon dioxide at the outlet of the turbine expander recovers the waste heat into the system through the heat exchanger, and then flows through the precooler. The supercritical carbon dioxide fluid is cooled to near the critical state point. The fluid flowing out of the precooler enters the compressor to be pressurized. After the fluid pressure increases, it is heated by the heat exchanger and then enters the solar collector to start a new cycle.

[0022] When there is excess solar energy during the day, the fourth valve is closed, and the first, second, third and fifth valves are opened. Part of the heat absorbed by the solar collector is stored in the heat storage in the form of thermal energy, and the other part is used to heat the carbon dioxide fluid in the pipeline. The fluid after absorbing heat enters the turbine expander to expand and do work, and then releases heat through the heat exchanger and precooler. The low-temperature and low-pressure carbon dioxide fluid in the low-pressure gas storage tank enters the circulation through the first valve, merges with the fluid in the circulation, and enters the compressor for pressurization. The low-temperature and high-pressure carbon dioxide fluid flowing out of the compressor is diverted, and part is stored in the high-pressure gas storage tank, and the other part continues to circulate. The amount of fluid stored in the high-pressure gas storage tank is the same as the amount of fluid released from the low-pressure gas storage tank, until the storage capacity of the high-pressure gas storage tank reaches the maximum, and the fluid that continues to enter the circulation passes through the heat exchanger and solar thermal collector in turn to absorb heat, and the above cycle is repeated;

[0023] When the lighting conditions are poor or there is no light at night, the first valve, the third valve and the fourth valve are opened, and the second valve and the fifth valve are closed. The low-temperature and high-pressure carbon dioxide fluid flows out from the high-pressure gas storage tank, enters the heat accumulator to absorb heat after heat exchange in the heat exchanger, and the supplementary heat device plays an auxiliary heating role; the high-temperature and high-pressure carbon dioxide fluid after absorbing heat does work in the turbine expander, enters the heat exchanger to exchange heat with the carbon dioxide released from the high-pressure gas storage tank, and then enters the precooler for further cooling, and then is stored in the low-pressure gas storage tank.

[0024] Furthermore, the compressed carbon dioxide energy storage system also includes a second compressor, a sixth valve and a seventh valve. The low-pressure gas storage tank is connected to the inlet of the second compressor, and the sixth valve is provided on the connecting pipeline. The outlet of the second compressor is connected to the high-pressure gas storage tank, and the seventh valve is provided on the connecting pipeline.

[0025] When there is sufficient sunlight during the day, the second and fifth valves are opened, and the fourth, third, fourth, sixth, and seventh valves are closed. The fluid is cooled by the precooler and then enters the compressor for pressurization. The generated low-temperature and high-pressure carbon dioxide flows through the heat exchanger and solar collector for heating and then enters the turbine expander to perform work. The fluid flowing out of the turbine expander is cooled by the heat exchanger and precooler and then enters the compressor for pressurization, starting a new cycle.

[0026] When there is excess solar energy during the day, the second, fifth, sixth and seventh valves are opened, and the first, third and fourth valves are closed. At this time, the low-temperature, low-pressure carbon dioxide in the low-pressure gas tank is released and enters the compressor for pressurization. The low-temperature, high-pressure carbon dioxide flowing out of the compressor enters the high-pressure gas tank for storage. The amount of fluid stored in the high-pressure gas tank is the same as the amount of fluid released from the low-pressure gas tank. At the same time, part of the heat absorbed by the solar collector is stored in the heat storage device in the form of thermal energy. The working state of the rest of the cycle is the same as when there is sufficient sunlight.

[0027] When the lighting conditions are poor or there is no light at night, the first valve, the third valve and the fourth valve are opened, and the second valve, the fifth valve, the sixth valve and the seventh valve are closed. The low-temperature and high-pressure carbon dioxide fluid flows out from the high-pressure gas storage tank, enters the heat accumulator to absorb heat after heat exchange in the heat exchanger, and the supplementary heat device plays an auxiliary heating role. After absorbing heat, the high-temperature and high-pressure carbon dioxide fluid performs work in the turbine expander, enters the heat exchanger to exchange heat with the carbon dioxide released from the high-pressure gas storage tank, and then enters the precooler for further cooling, and then is stored in the low-pressure gas storage tank.

[0028] Furthermore, the heat accumulator is a molten salt heat accumulator.

[0029] Furthermore, the compressors in the system are all connected to motors, which provide them with kinetic energy.

[0030] Beneficial effects:

[0031] Compared with Solution 1, the present invention can store heat and high-pressure gas at the same time without adding additional pressurizing equipment.

[0032] Compared with Solution 2, the present invention uses fewer parts, has a simpler structure, and saves costs.

[0033] Compared with Solution 3, the present invention uses only carbon dioxide as a working fluid, which reduces the complexity of the system structure and the possibility of working fluid leakage.

[0034] Compared with Scheme 4, the present invention stores heat and high-pressure carbon dioxide simultaneously, directly storing the fluid at the compressor outlet, eliminating the heat release process of the high-pressure fluid, that is, eliminating the heat exchange equipment.

[0035] In addition to the advantage of a smaller system component count, the present invention also minimizes the parameters of each system component, such as a reduced heat exchange area for the heat exchanger and a reduced flow rate for the turboexpander. Specifically, when designing the power generation system, most equipment, including the heat exchanger, precooler, turboexpander, piping, and valves, only needs to be designed for 100% of the system's design power generation during the day. However, the compressor's design flow rate needs to be increased to meet both daytime energy storage and power generation requirements. Alternatively, the system can be configured with two compressors: one for normal system power generation and the other specifically for energy storage, with its design flow rate being the flow rate required at 100% of the design power generation. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic structural diagram of a solar power generation system coupled with compressed carbon dioxide energy storage in Example 1;

[0037] Figure 2 This is a schematic structural diagram of a solar power generation system coupled with compressed carbon dioxide energy storage according to Example 2. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to specific embodiments.

[0039] Example 1

[0040] The main structure and connection relationship of the solar power generation system coupled with compressed carbon dioxide energy storage are as follows: Figure 1 As shown, it includes a heliostat field 1, a solar collector 2, a turbo expander 3, a generator 4, a precooler 5, a first valve 6, a low-pressure gas storage tank 7, a second valve 8, a motor 9, a compressor 10, a high-pressure gas storage tank 11, a third valve 12, a heat exchanger 13, a supplementary heat device 14, a molten salt heat accumulator 15, a fourth valve 16 and a fifth valve 17.

[0041] Among them, the heliostat field 1 is connected to the solar collector 2, the outlet of the solar collector 2 is connected to the inlet of the turbine expander 3, and the turbine expander 3 is connected to the generator 4; the outlet of the turbine expander 3 is connected to the high-temperature side inlet of the heat exchanger 13, the high-temperature side outlet of the heat exchanger 13 is connected to the inlet of the precooler 5, the outlet of the precooler 5 is connected to the inlet of the compressor 10, and a second valve 8 is provided between the precooler 5 and the compressor 10. At the same time, the compressor 10 is connected to the motor 9, and the outlet of the compressor 10 is connected to the low-temperature side inlet of the heat exchanger 13. The low-temperature side outlet of the heat exchanger 13 is divided into two routes, one of which is connected to the inlet of the solar collector 2, and a fifth valve 17 is provided on the connected pipeline, and the other route is connected to the inlet of the molten salt heat accumulator 15, and a fourth valve 16 is provided on the connected pipeline. The outlet of the molten salt heat accumulator 15 is connected to the inlet of the supplementary heat reservoir 14, and the outlet of the supplementary heat reservoir 14 is connected to the inlet of the turbine expander 3. The heliostat field 1, solar collector 2, turboexpander 3, generator 4, precooler 5, second valve 8, motor 9, compressor 10, heat exchanger 13, supplementary heat device 14, molten salt heat accumulator 15, fourth valve 16 and fifth valve 17 constitute a solar supercritical carbon dioxide power generation system.

[0042] The solar supercritical carbon dioxide power generation system is coupled with a compressed carbon dioxide energy storage system. This system includes a first valve 6, a low-pressure gas storage tank 7, a high-pressure gas storage tank 11, and a third valve 12. The low-pressure gas storage tank 7 is connected to the outlet of the precooler 5, with the first valve 6 installed on the connecting pipeline. The high-pressure gas storage tank 11 is located between the outlet of the compressor 10 and the low-temperature inlet of the heat exchanger 13, and the third valve 12 is installed on the connecting pipeline.

[0043] The working medium of the solar supercritical carbon dioxide power generation system and the compressed carbon dioxide energy storage system is supercritical carbon dioxide.

[0044] The solar supercritical carbon dioxide Brayton cycle operation process of the present invention is as follows:

[0045] During the day, when sunlight is abundant, the heliostat field 1 concentrates sunlight, converting it into heat that is absorbed by the solar collector 2. The heat absorbed by the solar collector 2 is used to heat the carbon dioxide fluid in the pipeline, raising its temperature. After absorbing heat, the fluid performs work in the turbine expander 3, driving the turbine expander 3 to rotate and generate electricity through the generator 4. The high-temperature, low-pressure supercritical carbon dioxide at the outlet of the turbine expander 3 passes through the heat exchanger 13, recovering waste heat back into the system. The fluid then flows through the precooler 5, cooling the supercritical carbon dioxide fluid to near its critical point. The fluid exiting the precooler 5 enters the compressor 10, where it is pressurized. The motor 9 then powers the compressor 10. After the fluid pressure increases, it is heated by the heat exchanger 13 before entering the solar collector 2, beginning a new cycle.

[0046] During the day, when there's excess solar energy, the excess energy can be stored while ensuring the system's stable external power generation. At this point, based on the aforementioned cycle, a portion of the heat absorbed by the solar collector 2 is absorbed by the molten salt in the molten salt accumulator 15 and stored as thermal energy. At this point, the fourth valve 16 is closed and the fifth valve 17 is opened. The fluid that has absorbed heat in the solar collector 2 enters the turbine expander 3 to expand and perform work, then releases heat through the heat exchanger 13 and precooler 5. At this point, the first valve 6 opens, allowing the low-temperature, low-pressure carbon dioxide fluid in the low-pressure gas storage tank 7 to enter the circulation through the first valve 6, merge with the circulating fluid, and enter the compressor 10 for pressurization. Simultaneously, the second valve 8 and the third valve 12 open, diverting the low-temperature, high-pressure carbon dioxide fluid flowing out of the compressor 10. A portion is stored in the high-pressure gas storage tank 11, while the remaining portion continues to circulate. The amount of fluid stored in the high-pressure gas storage tank 11 is equal to the amount of fluid released from the low-pressure gas storage tank 7, until the high-pressure gas storage tank 11 reaches its maximum storage capacity. The fluid that continues to enter the cycle passes through the heat exchanger 13 and the solar collector 2 in turn to absorb heat, and the above cycle is repeated.

[0047] When sunlight is low or there is no sunlight at night, the solar system cannot provide sufficient heat for the supercritical CO2 Brayton system. In this case, the fifth valve 17 is closed and the fourth valve 16 is opened. Low-temperature, high-pressure CO2 fluid flows from the high-pressure gas storage tank 11, passes through the open third valve 12, and enters the circulation. After heat exchange in the heat exchanger 13, it passes through the fourth valve 16 and enters the molten salt heat accumulator 15 to absorb heat. During this process, if the heat in the molten salt heat accumulator 15 gradually decreases and the fluid temperature cannot reach the inlet conditions of the turbine expander 3, the supplementary heat generator 14 is opened to heat the fluid. The high-temperature, high-pressure CO2 fluid then flows into the turbine 3 to perform work, and the generator 4 generates electricity. After performing work, the high-temperature, low-pressure CO2 fluid enters the heat exchanger 13 and precooler 5, releases heat, and is then stored in the low-pressure gas storage tank 7 through the first valve 6. At this point, the second valve 8 is closed, and the fluid no longer enters the compressor 10 for pressurization.

[0048] During the above cycle, since the high-pressure gas storage tank 11 stores low-temperature, high-pressure carbon dioxide from the outlet of the compressor 10, the fluid no longer passes through the heat exchanger 13 for heat exchange. Therefore, the fluid flow in the heat exchanger 13 can be kept stable, the heat exchange area can be saved, and the size of the heat exchanger 13 equipment can be reduced. When the lighting conditions are poor or there is no light at night, the fluid is heated by the molten salt heat accumulator 15 and the supplementary heat device 14 and enters the turbine expander 3 to perform work. It will then enter the heat exchanger 13 to exchange heat with the low-temperature fluid released from the high-pressure gas storage tank 11. This can make more full use of the thermal energy stored during the day when there is excess solar energy, while also ensuring that the heat exchanger 13 can work efficiently for a long time, maximizing the utilization rate of the equipment.

[0049] Example 2

[0050] Another structure of the present invention, such as Figure 2 As shown, based on the solar power generation system coupled with compressed carbon dioxide energy storage in Example 1, a compressor 18, a motor 19, a sixth valve 20, and a seventh valve 21 are added. A connecting pipeline is added to the low-pressure gas storage tank 7 and connected to the inlet of the compressor 18. The sixth valve 20 is installed on the connecting pipeline. At the same time, the compressor 10 is connected to the motor 19, and the outlet of the compressor 10 is connected to the high-pressure gas storage tank 11. The seventh valve 21 is installed on the connecting pipeline.

[0051] During the day when there is sufficient sunlight, the second valve 8 and the fifth valve 17 are opened, and the fourth valve 6, the third valve 12, the fourth valve 16, the sixth valve 20, and the seventh valve 21 are closed. The fluid is cooled by the precooler 5 and then enters the compressor 10 for pressurization. The generated low-temperature, high-pressure carbon dioxide flows through the heat exchanger 13 and the solar collector 2 for heating, then enters the turbine expander 3 to perform work. The fluid flowing out of the turbine expander 3 is cooled by the heat exchanger 13 and the precooler 5, then enters the compressor 10 for pressurization, starting a new cycle.

[0052] During the day, when solar energy is in excess, the second valve 8, the fifth valve 17, the sixth valve 20, and the seventh valve 21 are opened, while the first valve 6, the third valve 12, and the fourth valve 16 are closed. This releases the low-temperature, low-pressure carbon dioxide from the low-pressure gas storage tank 7 and pressurizes it in the compressor 18. The low-temperature, high-pressure carbon dioxide flowing out of the compressor 18 enters the high-pressure gas storage tank 11 for storage. The amount of fluid stored in the high-pressure gas storage tank 11 is the same as the amount of fluid released from the low-pressure gas storage tank 7. Simultaneously, a portion of the heat absorbed by the solar collector 2 is absorbed by the molten salt in the molten salt thermal accumulator 15 and stored as thermal energy. The remaining portion of the cycle operates as it would under sufficient sunlight.

[0053] When lighting conditions are poor or there is no light at night, the first valve 6, third valve 12, and fourth valve 16 are open, while the second valve 8, fifth valve 17, sixth valve 20, and seventh valve 21 are closed. Low-temperature, high-pressure carbon dioxide fluid flows out of the high-pressure gas storage tank 11, exchanges heat in the heat exchanger 13, and then enters the molten salt heat accumulator 15 to absorb heat. The supplementary heat generator 14 provides auxiliary heating. After absorbing heat, the high-temperature, high-pressure carbon dioxide fluid performs work in the turbine expander 3. It then enters the heat exchanger 13 to exchange heat with carbon dioxide released from the high-pressure gas storage tank 11. It then enters the precooler 5 for further cooling before being stored in the low-pressure gas storage tank 7.

[0054] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for a solar power generation system coupled with compressed carbon dioxide energy storage, characterized in that: The solar power generation system coupled with compressed carbon dioxide energy storage includes a solar supercritical carbon dioxide power generation system and a compressed carbon dioxide energy storage system; The solar supercritical carbon dioxide power generation system includes a heliostat field, a solar collector, a turbine expander, a generator, a precooler, a second valve, a compressor, a heat exchanger, a supplementary heat device, a heat accumulator, a fourth valve, and a fifth valve; The heliostat field is connected to a solar thermal collector, the solar thermal collector outlet is connected to a turbine expander inlet, and the turbine expander is connected to a generator; the turbine expander outlet is connected to a high-temperature side inlet of a heat exchanger, the high-temperature side outlet of the heat exchanger is connected to a precooler inlet, the precooler outlet is connected to a second valve and then to a compressor inlet, the compressor outlet is connected to a low-temperature side inlet of the heat exchanger, the low-temperature side outlet of the heat exchanger is divided into two paths, one path is connected to a fifth valve and then to a solar thermal collector inlet, and the other path is connected to a fourth valve and then to a heat accumulator inlet, the heat accumulator outlet is connected to a supplementary heat inlet, and the supplementary heat outlet is connected to the turbine expander inlet; The compressed carbon dioxide energy storage system includes a first valve, a low-pressure gas storage tank, a high-pressure gas storage tank, and a third valve; the low-pressure gas storage tank is connected to the outlet of the precooler, and the first valve is provided on the connecting pipeline; the high-pressure gas storage tank is connected to the third valve and then connected to the pipeline between the outlet of the compressor and the inlet of the low-temperature side of the heat exchanger; The working medium of the solar supercritical carbon dioxide power generation system and the compressed carbon dioxide energy storage system is supercritical carbon dioxide; The method comprises the following steps: when there is sufficient sunlight during the day, the first valve, the second valve, and the fifth valve are opened, and the third valve and the fourth valve are closed; the heat absorbed by the solar thermal collector is used to heat the carbon dioxide fluid in the pipeline; after absorbing the heat, the fluid performs work in the turbine expander, driving the turbine expander to rotate, and generating electricity externally through the generator; the high-temperature, low-pressure supercritical carbon dioxide at the outlet of the turbine expander passes through a heat exchanger to recover waste heat into the system; then, the supercritical carbon dioxide fluid passes through a precooler, and is cooled to near a critical state point; the fluid flowing out of the precooler enters a compressor to be pressurized; after the fluid pressure increases, it is heated by the heat exchanger, and then enters the solar thermal collector to start a new cycle; When there is excess solar energy during the day, the fourth valve is closed, and the first, second, third and fifth valves are opened. Part of the heat absorbed by the solar collector is stored in the heat storage in the form of thermal energy, and the other part is used to heat the carbon dioxide fluid in the pipeline. The fluid after absorbing heat enters the turbine expander to expand and do work, and then releases heat through the heat exchanger and precooler. The low-temperature and low-pressure carbon dioxide fluid in the low-pressure gas storage tank enters the circulation through the first valve, merges with the fluid in the circulation, and enters the compressor for pressurization. The low-temperature and high-pressure carbon dioxide fluid flowing out of the compressor is diverted, and part is stored in the high-pressure gas storage tank, and the other part continues to circulate. The amount of fluid stored in the high-pressure gas storage tank is the same as the amount of fluid released from the low-pressure gas storage tank, until the storage capacity of the high-pressure gas storage tank reaches the maximum, and the fluid that continues to enter the circulation passes through the heat exchanger and solar thermal collector in turn to absorb heat, and the above cycle is repeated; When the lighting conditions are poor or there is no light at night, the first valve, the third valve and the fourth valve are opened, and the second valve and the fifth valve are closed. The low-temperature and high-pressure carbon dioxide fluid flows out from the high-pressure gas storage tank, enters the heat accumulator to absorb heat after heat exchange in the heat exchanger, and the supplementary heat device plays an auxiliary heating role; the high-temperature and high-pressure carbon dioxide fluid after absorbing heat does work in the turbine expander, enters the heat exchanger to exchange heat with the carbon dioxide released from the high-pressure gas storage tank, and then enters the precooler for further cooling, and then is stored in the low-pressure gas storage tank.

2. The method according to claim 1, characterized in that The compressed carbon dioxide energy storage system also includes a second compressor, a sixth valve and a seventh valve. The low-pressure gas storage tank is connected to the inlet of the second compressor, and the sixth valve is provided on the connecting pipeline. The outlet of the second compressor is connected to the high-pressure gas storage tank, and the seventh valve is provided on the connecting pipeline.

3. The method according to claim 1, characterized in that The heat accumulator is a molten salt heat accumulator.

4. The method according to claim 2, characterized in that The compressors in the system are all connected to motors, which provide them with kinetic energy.

5. The method according to claim 2, characterized in that When there is sufficient sunlight during the day, the second and fifth valves are opened, and the fourth, third, fourth, sixth, and seventh valves are closed. The fluid is cooled by the precooler and then enters the compressor for pressurization. The generated low-temperature and high-pressure carbon dioxide flows through the heat exchanger and solar collector for heating and then enters the turbine expander to perform work. The fluid flowing out of the turbine expander is cooled by the heat exchanger and precooler and then enters the compressor for pressurization, starting a new cycle. When there is excess solar energy during the day, the second valve, the fifth valve, the sixth valve, and the seventh valve are opened, and the first valve, the third valve, and the fourth valve are closed. At this time, the low-temperature, low-pressure carbon dioxide in the low-pressure gas storage tank is released and enters the second compressor for pressurization. The low-temperature, high-pressure carbon dioxide flowing out of the second compressor enters the high-pressure gas storage tank for storage. The amount of fluid stored in the high-pressure gas storage tank is the same as the amount of fluid released from the low-pressure gas storage tank. At the same time, part of the heat absorbed by the solar thermal collector is stored in the heat storage tank in the form of thermal energy. When the lighting conditions are poor or there is no light at night, the first valve, the third valve and the fourth valve are opened, and the second valve, the fifth valve, the sixth valve and the seventh valve are closed. The low-temperature and high-pressure carbon dioxide fluid flows out from the high-pressure gas storage tank, enters the heat accumulator to absorb heat after heat exchange in the heat exchanger, and the supplementary heat device plays an auxiliary heating role. After absorbing heat, the high-temperature and high-pressure carbon dioxide fluid performs work in the turbine expander, enters the heat exchanger to exchange heat with the carbon dioxide released from the high-pressure gas storage tank, and then enters the precooler for further cooling, and then is stored in the low-pressure gas storage tank.

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