Energy storage and carbon sequestration system based on flexible enhanced geothermal system

Abstract

The utility model discloses an energy storage and carbon sequestration system based on a flexible enhanced geothermal system, and belongs to the technical field of energy storage. According to the utility model, the problems that the existing wind and light electricity abandoning rate is high, and the energy storage scale, energy storage time and energy storage efficiency of the conventional energy storage technology are limited to a certain extent are solved. A CO2 outlet of the heating device and an inlet of the flow adjusting device are correspondingly connected to an underground injection well and an underground production well of the enhanced geothermal field, and electric energy is provided for the heating device and the pump through wind and light abandoned electricity. On one hand, wind and light abandoned electricity is converted into CO2 internal energy to be stored, on the other hand, CO2 is injected into the ground, and the CO2 mineralization storage rate is increased through pressure fluctuation and temperature fluctuation. Compared with a traditional heat energy storage mode, the system has the advantages of being large in storage scale, flexible in energy storage time and high in response speed.

Description

Technical Field

[0001] The utility model relates to an energy storage and carbon sequestration system based on a flexible enhanced geothermal system, belonging to the technical field of energy storage. Background Art

[0002] As China's renewable energy installed capacity increases, the intermittent and uncertain wind and solar power equipment brings huge peak, frequency and phase regulation burdens to the power grid and peak-shaving power plants. Large-scale renewable energy output has strong random fluctuations, traditional power plants are relatively small, have insufficient regulation capabilities, and have high wind and solar power abandonment rates. Reasonable optimization of the ratio of wind power and photovoltaic installed capacity and the capacity of flexible regulation resources such as energy storage are important foundations for ensuring efficient transmission and consumption of new energy.

[0003] At present, most of the electrochemical energy storage applications in my country's wind power projects are represented by lithium iron phosphate, but its energy storage cost is high and it is difficult to apply on a large scale. In addition, the cycle life of lithium batteries also limits the working market of energy storage systems. Other conventional energy storage technologies include electronic energy storage, mechanical energy storage, thermal energy storage, etc., which have certain limitations in energy storage scale, energy storage time, energy storage efficiency, cost and response speed. Therefore, there is an urgent need for an energy storage technology that can meet the scale, long time, rapid response and appropriate cost. Utility Model Content

[0004] The utility model is to solve the above-mentioned technical problems and further provide an energy storage and carbon sequestration system based on a flexible enhanced geothermal system.

[0005] The technical solution adopted by the utility model to solve the above technical problems is:

[0006] A energy storage and carbon sequestration system based on a flexible enhanced geothermal system, comprising an enhanced geothermal field, a CO2 storage tank, a pump and a heating device connected in sequence to the outlet side of the CO2 storage tank through pipelines, and a cooling device, an expansion device and a flow regulating device connected in sequence to the inlet side of the CO2 storage tank through pipelines, the CO2 outlet of the heating device and the inlet of the flow regulating device being connected to the underground injection well and the underground production well of the enhanced geothermal field respectively, and the heating equipment and the pump are provided with electric energy by the abandoned wind and solar power.

[0007] Furthermore, the heating method of the heating device is electric heating.

[0008] Furthermore, the heating method of the heating device is heat exchange by a heat pump.

[0009] Furthermore, the temperature of CO2 after being heated by the heating device ranges from 200 to 400°C.

[0010] Furthermore, the pressure of CO2 after being pressurized by the pump ranges from 20MPa to 40MPa.

[0011] Compared with the prior art, the utility model has the following effects:

[0012] The utility model introduces wind and solar power abandonment into the enhanced geothermal system. On the one hand, it converts wind and solar power abandonment into CO2 internal energy storage, that is, converts electrical energy into pressure potential energy. On the other hand, it injects CO2 into the ground to accelerate the CO2 mineralization and storage rate through pressure fluctuations and temperature fluctuations. Compared with traditional thermal energy storage methods, the advantages of the utility model are large storage scale, flexible energy storage time, and fast response speed. In addition, by utilizing the characteristics of high temperature, high pressure, low permeability, and low thermal conductivity of the enhanced geothermal system, CO2 loss is smaller, and the energy storage temperature can be increased to 400°C, achieving higher energy storage efficiency. The utility model achieves energy storage and carbon sequestration by flexibly operating the enhanced geothermal system to change the temperature, pressure, and flow rate of the CO2 working fluid inside the enhanced geothermal field.

[0013] In enhanced geothermal fields, CO2 can be stored at temperatures up to 400°C, which improves power generation efficiency and energy storage efficiency. By real-time regulation of the temperature, pressure, and flow of the working fluid inside the enhanced geothermal field, dynamic energy storage is achieved, and the energy storage duration is extremely flexible.

[0014] The dynamic changes in temperature and pressure in the flexible enhanced geothermal system increase the rate of CO2 underground mineralization storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a structural schematic diagram of a flexible enhanced geothermal system.

[0016] In the figure:

[0017] 1. Enhanced geothermal field; 2. CO2 storage tank; 3. Pump; 4. Heating equipment; 5. Cooling equipment; 6. Expansion equipment; 7. Flow regulation equipment. DETAILED DESCRIPTION

[0018] Specific implementation method 1: Combination Figure 1 This embodiment is explained, and the technical scheme in the embodiment of the utility model is clearly and completely described. Obviously, the described embodiment is only a part of the embodiment of the utility model, rather than all the embodiments. Based on the embodiment in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0019] It should be noted that the descriptions of the present invention regarding directions such as "front", "back", "left", "right", "inside", "outside", "left side", "right side", "upper", "lower", "top", "bottom", etc. are all defined based on the relationship between the orientations or positions shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the structure described must be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention. In the description of the present invention, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0020] In the description of the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] A energy storage and carbon sequestration system based on a flexible enhanced geothermal system comprises an enhanced geothermal field 1, a CO2 storage tank 2, a pump 3 and a heating device 4 connected in sequence to the outlet side of the CO2 storage tank 2 through pipelines, and a cooling device 5, an expansion device 6 and a flow regulating device 7 connected in sequence to the inlet side of the CO2 storage tank 2 through pipelines. The CO2 outlet of the heating device 4 and the inlet of the flow regulating device 7 are correspondingly connected to the underground injection well and the underground production well of the enhanced geothermal field 1, and the heating device 4 and the pump 3 are provided with electric energy by wind and solar power abandonment.

[0022] The above-mentioned flexible control method of the energy storage and carbon sequestration system based on the flexible enhanced geothermal system comprises the following steps:

[0023] Step 1, preparation stage:

[0024] Store CO2 in the CO2 storage tank 2, check and ensure that the flexible enhanced geothermal system is operating normally; store the captured CO2 in the CO2 storage tank 2, and ensure that there is enough CO2 supply in the CO2 storage tank 2 for subsequent system operations. Check the status of the pump 3, heating equipment 4, underground injection well, underground production well, flow regulating equipment 7, expansion equipment 6 and cooling equipment 5 to ensure the normal operation of each device. Adjust the system temperature, pressure, and flow to the reference state, and balance the system as a whole. The reference state is a state where the fluid temperature is equal to the geothermal reservoir temperature and the fluid pressure is equal to the initial geothermal reservoir pressure. The overall balance of the system means that the fluid state at all locations in the system does not change with time.

[0025] Step 2, energy storage process:

[0026] The abandoned wind and solar power is collected to provide electric energy for the heating device 4 and the pump 3. The heating device 4 is started to heat the high-pressure CO2 from the pump 3 to a high-temperature and high-pressure state. By distributing the abandoned wind and solar power to the heating device 4 and the pump 3 respectively, electric energy is provided to the heating device 4 and the pump 3, and the pressure ratio of the pump 3 can be effectively improved.

[0027] The CO2 is transported to the underground injection well by the pump 3 and injected into the enhanced geothermal field 1 for storage. At the same time, the CO2 flow rate is reduced by the flow regulating device. At this time, the internal temperature and pressure of the enhanced geothermal field 1 rise;

[0028] Step 3, maintenance phase:

[0029] The CO2 flow rate inside the enhanced geothermal field 1 is timely adjusted by the flow regulating device 7, and the internal temperature and pressure of the enhanced geothermal field 1 are monitored in real time by the monitoring device to ensure that the system is in a stable energy storage state; when the underground injection well flow rate is increased and the underground production well flow rate is reduced, the reservoir pressure rises, and conversely, when the underground injection well flow rate is reduced and the underground production well flow rate is increased, the reservoir pressure decreases. The flow regulating device 7 is adjusted to ensure that the CO2 flow rate inside the enhanced geothermal field 1 is maintained at an appropriate level to prevent excessive pressure from causing system instability. When the reservoir pressure is greater than the maximum allowable pressure, it indicates that the flow rate in the system is too large, and it is necessary to reduce the underground injection well flow rate and increase the underground production well flow rate. When the reservoir pressure is less than the minimum allowable pressure, the opposite flow adjustment is required.

[0030] Step 4: Energy release:

[0031] When the power demand is greater than the supply, the flow regulating device 7 is started to increase the CO2 flow to release the high-temperature and high-pressure CO2 in the enhanced geothermal field 1 to the expansion device 6 for power generation, and the heat energy is converted into electrical energy. The CO2 after power generation is cooled into liquid by the cooling device 5 and then stored again in the CO2 storage tank 2, forming a closed loop cycle, preparing for the next energy storage and power generation operation. The flow regulating device 7 is started to release CO2, and the heat energy is converted into electrical energy through the expansion power generation device, and the CO2 is cooled and recovered through the cooling device 5 and the CO2 storage tank 2.

[0032] The CO2 storage tank 2 is used to store high-pressure CO2 liquid; the pump 3 is used to transport CO2 from the CO2 storage tank 2 to the underground enhanced geothermal field 1; the heating device 4 is used to heat CO2 to a high-temperature state and enter the enhanced geothermal field 1 for storage through the underground injection well; the underground production well is used to transport CO2 from the enhanced geothermal field 1 to the ground expansion device 6; the flow regulating device 7 is located at the outlet of the underground production well and is used to regulate the CO2 flow and pressure in the system and the reserves in the enhanced geothermal field 1. The expansion device 6 is used to generate electricity by directly expanding the high-temperature and high-pressure CO2, and the cooling device 5 is used to cool the expanded CO2 into liquid.

[0033] This utility model introduces wind and solar power abandonment into the enhanced geothermal system. On the one hand, it converts wind and solar power abandonment into CO2 internal energy storage, that is, converts electrical energy into pressure potential energy. On the other hand, it injects CO2 into the ground to accelerate the CO2 mineralization and storage rate through pressure fluctuations and temperature fluctuations. Compared with traditional thermal energy storage methods, the advantages of this utility model are large storage scale, flexible energy storage time, and fast response speed. In addition, by utilizing the characteristics of high temperature, high pressure, low permeability, and low thermal conductivity of the enhanced geothermal system, CO2 loss is smaller, and the energy storage temperature can be increased to 400°C, achieving higher energy storage efficiency.

[0034] The wind and solar power abandonment refers to the excess electric energy generated by wind and solar power equipment.

[0035] When the supply and demand of electricity is balanced, the temperature, pressure and flow rate inside the enhanced geothermal field 1 are all at the reference value. When there is too much abandoned wind and solar power, the abandoned wind and solar power is supplied to the pump 3 and the heating device 4, and the flow rate in the system is reduced through the flow regulating device 7, the workmanship of the pump 3 is improved, and the CO2 is compressed and heated to a high temperature and high pressure state (the heating temperature is between 200-400℃ according to the actual situation, and the pressure is between 20MPa and 40MPa according to the depth of the enhanced geothermal field 1), and pumped 3 into the underground enhanced geothermal field 1 for storage. At this time, the temperature and pressure inside the enhanced geothermal field 1 rise, and the flow rate decreases.

[0036] When the power supply is less than the demand, the flow regulating device 7 is opened to release CO2 to the expansion device 6 for power generation. At this time, the temperature and pressure of CO2 inside the enhanced geothermal field 1 decreases and the flow increases. Through the flexible operation of the enhanced geothermal system, the wind and solar power can be stored in the enhanced geothermal field 1 for a period of time ranging from hours to years.

[0037] The utility model realizes energy storage and carbon sequestration by flexibly operating the enhanced geothermal system to change the temperature, pressure and flow rate of the CO2 working medium inside the enhanced geothermal field 1.

[0038] In the enhanced geothermal field 1, CO2 can be stored at a high temperature of up to 400°C, which improves the efficiency of power generation and energy storage. By real-time regulation of the temperature, pressure and flow of the working fluid inside the enhanced geothermal field 1, dynamic energy storage is achieved, and the energy storage duration is extremely flexible.

[0039] The CO2 injected into the enhanced geothermal field 1 is gradually mineralized under high temperature and high pressure to achieve long-term carbon sequestration. The dynamic changes in pressure and temperature accelerate the mineralization rate of CO2 and improve the sequestration efficiency. The mineralization of CO2 in the enhanced geothermal field 1 is regularly monitored to ensure the safety and effectiveness of the carbon sequestration process.

[0040] The specific structures of the heating device 4, the cooling device 5, the expansion device 6 and the flow regulating device 7 in the present invention are all prior art and will not be described in detail here.

[0041] The heating device 4 is electrically heated. In this design, the heating device 4 is provided with electric energy by introducing abandoned wind and solar power to directly heat the liquid CO2.

[0042] The temperature of CO2 after being heated by the heating device 4 is in the range of 200 to 400°C.

[0043] The pressure of CO2 after pressurization by pump 3 ranges from 20MPa to 40MPa.

[0044] Specific implementation method 2: Combination Figure 1 In this embodiment, the heating method of the heating device 4 is heat exchange by heat pump. In this design, the heating device 4 is a heat pump, and the wind and solar power are introduced to provide electricity for the heat pump, and the liquid CO2 exchanges heat with the heat exchange medium in the heat pump to increase the temperature. According to the heating temperature requirement of CO2, the heat pump can be connected in series with the heating wire to ensure the high temperature heating requirement (such as 400°C). The other components and connection relationships are the same as those in the first embodiment.

[0045] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes within the technical scope disclosed by the present invention according to the technical scheme and the utility model concept of the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An energy storage and carbon sequestration system based on a flexible enhanced geothermal system, characterized in that: The invention comprises an enhanced geothermal field (1), a CO2 storage tank (2), a pump (3) and a heating device (4) connected in sequence to the outlet side of the CO2 storage tank (2) through pipelines, and a cooling device (5), an expansion device (6) and a flow regulating device (7) connected in sequence to the inlet side of the CO2 storage tank (2) through pipelines. The CO2 outlet of the heating device (4) and the inlet of the flow regulating device (7) are connected to the underground injection well and the underground production well of the enhanced geothermal field (1) respectively, and the heating device (4) and the pump (3) are provided with electric energy through the abandoned wind and solar power.

2. The energy storage and carbon sequestration system based on the flexible enhanced geothermal system according to claim 1, characterized in that: The heating method of the heating device (4) is electric heating.

3. The energy storage and carbon sequestration system based on the flexible enhanced geothermal system according to claim 1, characterized in that: The heating method of the heating device (4) is heat exchange by heat pump.

4. The energy storage and carbon sequestration system based on the flexible enhanced geothermal system according to claim 1, characterized in that: The temperature of CO2 after being heated by the heating device (4) is in the range of 200 to 400°C.

5. The energy storage and carbon sequestration system based on the flexible enhanced geothermal system according to claim 1, characterized in that: The pressure of CO2 after pressurization by pump (3) ranges from 20 MPa to 40 MPa.

Images