A compressed carbon dioxide energy storage system coupled with battery energy storage and method

Abstract

The application discloses a compressed carbon dioxide energy storage system coupled with a battery energy storage system and a method thereof, which comprises a compressed carbon dioxide energy storage module, a battery energy storage module, and a power grid and a power generation device connected to the compressed carbon dioxide energy storage module and the battery energy storage module in parallel. The compressed carbon dioxide energy storage module comprises a low-pressure carbon dioxide storage tank and a high-pressure carbon dioxide storage tank. The outlet of the low-pressure carbon dioxide storage tank is connected to the inlet of the high-pressure carbon dioxide storage tank through a first throttling valve and a compressor. The outlet of the high-pressure carbon dioxide storage tank is connected to the inlet of the low-pressure carbon dioxide storage tank through a second throttling valve and an expander. The battery energy storage module is connected to the power grid and the power generation device in parallel to store and release energy. The application couples the battery energy storage system to the compressed carbon dioxide energy storage system, uses the non-power-limited characteristics of the battery energy storage system to reduce the phenomenon of abandoned wind and abandoned light, and uses the short reaction time of the battery energy storage to smooth the transition, thereby effectively avoiding the disadvantage of slow reaction of the large-scale compressed energy storage system.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and in particular to a compressed carbon dioxide energy storage system and method coupled with battery energy storage. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] The large-scale utilization of renewable energy is considered an effective way to address increasingly severe environmental and energy problems. However, due to the intermittent and fluctuating nature of renewable energy, its large-scale grid connection poses a significant challenge to the stable operation of the power grid. Therefore, energy storage technology combined with renewable energy is considered an effective method to solve these challenges. Compressed carbon dioxide (CCC) energy storage systems, with their advantages of low cost, environmental friendliness, high efficiency, large-capacity installation, and lack of restriction by special geographical conditions, are receiving increasing attention. Besides CCC energy storage systems, the most widely used energy storage system is currently electrochemical energy storage system, which has the advantage of rapid charge and discharge speeds. However, due to its cost limitations, it cannot be installed and used on a large scale.

[0004] The compressed carbon dioxide energy storage system consists of a low-pressure storage tank, a high-pressure storage tank, a compressor, and an expander. During the energy storage phase, the compressor compresses the low-pressure carbon dioxide stored in the low-pressure tank to a high-pressure state, and then stores it in the high-pressure storage tank. During the energy release phase, the carbon dioxide stored in the high-pressure storage tank is released and enters the expander to do work. The expander drives a generator to produce electricity, and the expanded low-pressure carbon dioxide is stored in the low-pressure storage tank. However, the pressure ratio at both ends of the compressor and the expansion ratio at both ends of the expander always vary within a certain range, so the system can only store and release energy within a certain power range. Furthermore, this energy storage system also has the following problems: the time required for the system to reach the required energy storage / release power is on the order of several minutes, making it unable to quickly adjust and smooth the unstable output of renewable energy sources. Summary of the Invention

[0005] To address the aforementioned issues, this invention proposes a compressed carbon dioxide energy storage system and method coupled with battery energy storage. By combining a battery energy storage system and a compressed carbon dioxide energy storage system, the advantages of the compressed carbon dioxide energy storage system (which can be installed in large capacity) and the battery energy storage system (which can be charged and discharged quickly) are fully utilized.

[0006] In some implementations, the following technical solutions are adopted:

[0007] A compressed carbon dioxide energy storage system coupled with battery energy storage, comprising:

[0008] The compressed carbon dioxide energy storage module includes a low-pressure carbon dioxide storage tank and a high-pressure carbon dioxide storage tank. The outlet of the low-pressure carbon dioxide storage tank is connected to the inlet of the high-pressure carbon dioxide storage tank after passing through a first throttle valve and a compressor. The outlet of the high-pressure carbon dioxide storage tank is connected to the inlet of the low-pressure carbon dioxide storage tank after passing through a second throttle valve and an expander.

[0009] The battery energy storage module is connected in parallel with the compressed carbon dioxide energy storage module, and together they are connected to the power grid and power generation equipment to perform energy storage and release.

[0010] In other embodiments, the following technical solutions are adopted:

[0011] A method for operating a compressed carbon dioxide energy storage system coupled with battery energy storage includes:

[0012] When renewable energy generation exceeds the required electricity, the battery energy storage module can convert the excess electrical energy into chemical energy and store it in the battery during operation; the compressed carbon dioxide energy storage module can compress the carbon dioxide stored in the low-pressure gas tank to a high-pressure state through a compressor during operation and store it in the high-pressure gas tank.

[0013] When renewable energy generation is less than the required electricity, the battery energy storage module can convert the chemical energy in the battery into electrical energy and transmit it to the grid during operation; the compressed carbon dioxide energy storage module can expand the high-pressure carbon dioxide stored in the high-pressure gas tank through the expander to do work, and the resulting low-pressure carbon dioxide is stored in the low-pressure gas tank during operation.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] (1) This invention couples a battery energy storage system to a compressed carbon dioxide energy storage system. By using the power-unlimited characteristics of the battery energy storage system, the curtailment of wind and solar power can be reduced. Secondly, the low cost advantage of the compressed energy storage system can be leveraged to reduce the cost of the hybrid energy storage system. Furthermore, the short response time of the battery energy storage system facilitates a smooth transition, effectively avoiding the drawback of slow response in large-scale compressed energy storage systems.

[0016] (2) Within the power limit of the compressed energy storage system, the present invention, based on the fact that the power of the compressor and expander is a function of the pressure ratio, can adjust the opening of the throttle valve according to the power of the compressor or expander, with the help of feedback control of the PID module, so that the pressure ratio on both sides of the compressor or expander meets the power requirements.

[0017] In addition to the power limitations of compressed energy storage systems, battery energy storage is used to rapidly consume and release power, thereby achieving the power regulation function of the energy storage system.

[0018] Other features and advantages of the invention 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 the invention. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the compressed carbon dioxide energy storage system coupled with battery energy storage in an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of a multi-stage compressor or expander in an embodiment of the present invention;

[0021] Among them, 1. low-pressure gas storage tank, 2. first throttle valve, 3. first PID controller, 4. compressor, 5. battery energy storage module, 6. high-pressure gas storage tank, 7. second throttle valve, 8. second PID controller, and 9. expander. Detailed Implementation

[0022] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0023] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0024] Example 1

[0025] In one or more embodiments, a compressed carbon dioxide energy storage system coupled with battery energy storage is disclosed, combining... Figure 1 Specifically, it includes:

[0026] The compressed carbon dioxide energy storage module includes a low-pressure carbon dioxide storage tank (hereinafter referred to as low-pressure storage tank 1) and a high-pressure carbon dioxide storage tank (hereinafter referred to as high-pressure storage tank 6). The outlet of the low-pressure storage tank 1 is connected to the inlet of the high-pressure storage tank 6 after passing through the first throttle valve 2 and the compressor 4. The outlet of the high-pressure storage tank 6 is connected to the inlet of the low-pressure storage tank 1 after passing through the second throttle valve 7 and the expander 9.

[0027] The first PID controller 3 is connected to the first throttle valve 2 and is used to control the opening of the first throttle valve 2 so that the pressure ratio on both sides of the compressor 4 meets the power requirements; the second PID controller 8 is connected to the second throttle valve 7 so that the pressure ratio on both sides of the expander 9 meets the power requirements.

[0028] Battery energy storage module 5 is connected in parallel with compressed carbon dioxide energy storage module, and together they are connected to the power grid and power generation equipment to perform energy storage and release.

[0029] It should be noted that the compressor in this embodiment includes an electric motor used in conjunction with it, and the expander includes a generator used in conjunction with it.

[0030] As an optional implementation method, combined with Figure 2 The compressor 4 or expander 9 has at least one stage. When the compressor 4 or expander 9 has multiple stages, each stage of the compressor 4 or expander 9 is connected through a carbon dioxide pipeline. That is, the outlet of the previous stage compressor 4 or expander 9 is the inlet of the next stage, and the outlet of the last stage is connected to the high-pressure gas storage tank 6 or the low-pressure gas storage tank 1.

[0031] The purpose of setting up a multi-stage compressor 4 or expander 9 in this embodiment is that when the pressure in the high-pressure gas tank 6 is too high, the pressure ratio is too high and it cannot be compressed in one go, so multi-stage compression is required. The expansion process is the same.

[0032] During periods of low electricity demand or when renewable energy generation exceeds the required electricity, the excess power will drive the energy storage system. The battery energy storage module 5 can convert excess electrical energy into chemical energy and store it in the battery during operation; the compressed carbon dioxide energy storage module can compress the carbon dioxide stored in the low-pressure gas storage tank 1 to a high-pressure state through the compressor 4 during operation and store it in the high-pressure gas storage tank 6.

[0033] In this embodiment, for renewable energy power generation to be connected to the grid, the power generation equipment is connected to the energy storage system, and then connected to the grid (the purpose is to stabilize the frequency of the grid-connected power, because the frequency fluctuation of electricity directly generated by renewable energy is very large, while the normal frequency deviation of the grid is ±0.5Hz, so the addition of the energy storage system can stably discharge to the grid within the frequency error allowable range). This grid-connected power is the energy storage power.

[0034] The power-consuming device in the compressed carbon dioxide energy storage module is the compressor. Its power consumption is mainly related to the compressor's pressure ratio. The minimum pressure ratio is the ratio of the high-pressure storage tank pressure to the low-pressure storage tank pressure (obtained when the valve is fully open in the initial stage, at which point the compressor inlet pressure is the low-pressure storage tank pressure and the outlet pressure is the high-pressure storage tank pressure). This limits the compressor's minimum power. Theoretically, the maximum pressure ratio can be very large because slightly opening the throttle valve can keep the compressor outlet pressure the same as the high-pressure storage tank pressure, but the inlet pressure can drop very low due to the throttle valve's pressure reduction, thus allowing for a very high pressure ratio. However, the compressor's power consumption will not increase indefinitely because a small throttle valve opening not only means a larger pressure ratio but also a smaller energy storage flow rate. Therefore, the compressor's actual power consumption also has a power upper limit. The aforementioned minimum and upper power limits constitute the constraints of the compressed carbon dioxide energy storage module. The expansion process follows the same principle.

[0035] Specifically, during the energy storage process, the second throttle valve 7 is in the closed state, and neither the second PID controller 8 nor the expander 9 works.

[0036] When the energy storage power is lower than the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module starts to work, reacts quickly and stores energy at a lower power. At the same time, the compressor starts, and the low-pressure carbon dioxide in the low-pressure carbon dioxide storage tank is compressed into high-pressure carbon dioxide and stored in the high-pressure carbon dioxide storage tank. The compressed carbon dioxide energy storage module gradually enters the working state.

[0037] When the energy storage power is within the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module stops working, and the compressed carbon dioxide energy storage module operates independently. As the compression process proceeds, the opening of the first throttle valve is adjusted in real time through the first PID feedback regulation according to the power consumption required by the compressor to achieve variable power operation of the compressed carbon dioxide energy storage module.

[0038] When the energy storage capacity exceeds the power limit of the compressed carbon dioxide energy storage module, the compressed carbon dioxide energy storage module and the battery energy storage module work simultaneously to increase the storage capacity and continue to complete the energy storage work until the energy storage process ends.

[0039] It should be noted that when the energy storage capacity is lower than the power limit of the compressed carbon dioxide energy storage module, the energy below the power limit cannot be stored because the compressor pressure ratio has a minimum value, as mentioned above. Conversely, when the energy storage capacity is higher than the power limit of the compressed carbon dioxide energy storage module, this energy also cannot be stored. These two factors combined are a significant reason for the large-scale curtailment of wind and solar power. The expansion process follows the same principle.

[0040] During peak electricity demand periods or when renewable energy generation is less than the required amount, the shortfall in power generation will be provided by the energy storage system. The battery energy storage module 5 can convert the chemical energy in the battery into electrical energy and transmit it to the grid during operation; the compressed carbon dioxide energy storage module can expand the high-pressure carbon dioxide stored in the high-pressure gas storage tank 6 through the expander 9 to produce low-pressure carbon dioxide, which is then stored in the low-pressure gas storage tank 1.

[0041] Specifically, during the energy release process, the first throttle valve 2 is in the closed state, and neither the first PID controller 3 nor the compressor 4 works.

[0042] When the energy release power is lower than the power limit of the compressed carbon dioxide energy storage module, the battery energy storage starts to work, reacts quickly and releases energy at a lower power. At the same time, the expander 9 starts to start, and the high-pressure carbon dioxide in the high-pressure carbon dioxide storage tank 6 expands into low-pressure carbon dioxide and flows into the low-pressure carbon dioxide storage tank 1 for storage. The compressed carbon dioxide system gradually enters the working state.

[0043] When the energy release power is within the power limit of the compressed carbon dioxide energy storage module, the battery energy storage stops working and the compressed carbon dioxide energy storage system operates independently. As the energy release process proceeds, the opening of the second throttle valve is adjusted in real time through the second PID feedback regulation according to the power required by the expander to achieve variable power operation of the compressed carbon dioxide system.

[0044] When the released energy power exceeds the power limit of the compressed carbon dioxide energy storage module, the compressed carbon dioxide system and the battery energy storage work simultaneously to increase the released power and continue to complete the energy release work until the energy release process ends.

[0045] Example 2

[0046] In one or more embodiments, a method for operating a compressed carbon dioxide energy storage system coupled with battery energy storage is disclosed, comprising:

[0047] When renewable energy generation exceeds the required electricity, the battery energy storage module can convert the excess electrical energy into chemical energy and store it in the battery during operation; the compressed carbon dioxide energy storage module can compress the carbon dioxide stored in the low-pressure gas tank to a high-pressure state through a compressor during operation and store it in the high-pressure gas tank.

[0048] When renewable energy generation is less than the required electricity, the battery energy storage module can convert the chemical energy in the battery into electrical energy and transmit it to the grid during operation; the compressed carbon dioxide energy storage module can expand the high-pressure carbon dioxide stored in the high-pressure gas tank through the expander to do work, and the resulting low-pressure carbon dioxide is stored in the low-pressure gas tank during operation.

[0049] Based on the power consumption required by the compressor or expander, the opening of the first or second throttle valve is adjusted in real time through PID feedback regulation to achieve variable power operation of the compressed carbon dioxide energy storage module.

[0050] The specific implementation of the above process has been described in detail in Example 1, and will not be repeated here.

[0051] While the specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A compressed carbon dioxide energy storage system coupled with battery energy storage, characterized in that, include: The compressed carbon dioxide energy storage module includes a low-pressure carbon dioxide storage tank and a high-pressure carbon dioxide storage tank. The outlet of the low-pressure carbon dioxide storage tank is connected to the inlet of the high-pressure carbon dioxide storage tank after passing through a first throttle valve and a compressor. The outlet of the high-pressure carbon dioxide storage tank is connected to the inlet of the low-pressure carbon dioxide storage tank after passing through a second throttle valve and an expander. The first throttle valve is connected to the first PID controller, which controls the opening of the first throttle valve so that the pressure ratio on both sides of the compressor meets the power requirements. The second throttle valve is connected to the second PID controller, which controls the opening of the second throttle valve so that the pressure ratio on both sides of the expander meets the power requirements. The battery energy storage module is connected in parallel with the compressed carbon dioxide energy storage module, and together they are connected to the power grid and power generation equipment to perform energy storage and release. When renewable energy generation exceeds the required electricity, the battery energy storage module can convert the excess electrical energy into chemical energy and store it in the battery during operation; The compressed carbon dioxide energy storage module can compress carbon dioxide stored in the low-pressure storage tank to a high-pressure state through a compressor during operation and store it in the high-pressure storage tank. When the energy storage power is lower than the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module starts to store energy, while the compressed carbon dioxide energy storage module gradually enters the working state, compressing the carbon dioxide stored in the low-pressure gas tank to a high-pressure state and storing it in the high-pressure gas tank. When the energy storage power is within the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module stops working and the compressed carbon dioxide energy storage module operates independently; the opening of the first throttle valve is adjusted in real time according to the power consumption required by the compressor to achieve variable power operation of the compressed carbon dioxide energy storage module. When the energy storage power exceeds the power limit of the compressed carbon dioxide energy storage module, the compressed carbon dioxide energy storage module and the battery energy storage module work simultaneously to increase the storage capacity until the energy storage process ends. When renewable energy generation is less than the required electricity, the battery energy storage module can convert the chemical energy in the battery into electrical energy and transmit it to the grid during operation; the compressed carbon dioxide energy storage module can expand the high-pressure carbon dioxide stored in the high-pressure gas tank through the expander to do work, and the resulting low-pressure carbon dioxide is stored in the low-pressure gas tank during operation.

2. The compressed carbon dioxide energy storage system coupled with battery energy storage as described in claim 1, characterized in that, When the energy release power is lower than the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module begins to release energy, and at the same time the compressed carbon dioxide energy storage module gradually enters the working state, expanding the high-pressure carbon dioxide in the high-pressure carbon dioxide storage tank into low-pressure carbon dioxide and storing it in the low-pressure carbon dioxide storage tank. When the released energy power is within the power limit of the compressed carbon dioxide energy storage module, the battery energy storage module stops working and the compressed carbon dioxide energy storage module operates independently; the opening of the second throttle valve is adjusted in real time according to the power required by the expander to achieve variable power operation of the compressed carbon dioxide energy storage module. When the released energy power exceeds the power limit of the compressed carbon dioxide energy storage module, the compressed carbon dioxide energy storage module and the battery energy storage module work simultaneously to increase the released power until the energy release process ends.

3. The compressed carbon dioxide energy storage system coupled with battery energy storage as described in claim 1, characterized in that, The compressor or expander has at least one stage; when the compressor or expander has multiple stages, each stage of the compressor or expander is connected by a pipeline, and the outlet of the previous stage compressor or expander is connected to the inlet of the next stage compressor or expander.

4. A method of operating a compressed carbon dioxide energy storage system coupled with battery energy storage as described in any one of claims 1-3, characterized in that, include: When renewable energy generation exceeds the required electricity, the battery energy storage module can convert the excess electrical energy into chemical energy and store it in the battery during operation; The compressed carbon dioxide energy storage module can compress carbon dioxide stored in the low-pressure storage tank to a high-pressure state through a compressor during operation and store it in the high-pressure storage tank. When renewable energy generation is less than the required electricity, the battery energy storage module can convert the chemical energy in the battery into electrical energy and transmit it to the grid during operation; the compressed carbon dioxide energy storage module can expand the high-pressure carbon dioxide stored in the high-pressure gas tank through the expander to do work, and the resulting low-pressure carbon dioxide is stored in the low-pressure gas tank during operation.

5. The working method as described in claim 4, characterized in that, Also includes: Based on the power consumption required by the compressor or expander, the opening of the first or second throttle valve is adjusted in real time through PID feedback regulation to achieve variable power operation of the compressed carbon dioxide energy storage module.

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