Geothermal development system coupled with compressed carbon dioxide energy storage

Abstract

The invention discloses a geothermal development system coupled with compressed carbon dioxide energy storage, and relates to the technical field of geothermal energy, the geothermal development system coupled with compressed carbon dioxide energy storage comprises a first carbon dioxide storage tank, a second carbon dioxide storage tank, a compression system, a geothermal development well, a power generation system and a heat storage system; the terrestrial heat development well extends into the hot dry rock and is provided with an inner pipe and an outer pipe; the compression system communicates with an outlet of the first carbon dioxide storage tank and an inlet of the second carbon dioxide storage tank, an outlet of the second carbon dioxide storage tank communicates with the end, away from the hot dry rock, of the outer pipe, the end, away from the hot dry rock, of the inner pipe communicates with an inlet of the power generation system, and an outlet of the power generation system communicates with an inlet of the first carbon dioxide storage tank. Carbon dioxide is used as a working medium of the whole system, compressed carbon dioxide energy storage and geothermal energy development and utilization are coupled, the energy utilization rate is high, environment friendliness is achieved, and various requirements of energy storage, development and utilization and carbon emission reduction are met.

Description

Technical Field

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

[0002] As the global energy structure accelerates its transition to a low-carbon model, the efficiency of relying solely on clean energy sources is insufficient, highlighting the increasing importance of the coordinated development of clean technologies. Compressed carbon dioxide energy storage / power generation technology, due to its compact system and high energy conversion efficiency, is a highly promising cutting-edge technology and is widely compatible with various green energy sources. Geothermal energy, as an abundant, renewable, and stable baseload energy source, plays a crucial role in optimizing the energy structure, necessitating the construction of a multi-dimensional geothermal development system.

[0003] Currently, traditional geothermal energy development faces two major technological bottlenecks. First, hydrothermal geothermal systems rely on extraction and reinjection technologies, but changes in fluid composition during reinjection can easily lead to mineral scaling and microbial growth, causing reservoir and wellbore blockage and affecting the long-term stable operation of the system. Second, enhanced geothermal systems developed from hot dry rock require the construction of artificial fracture networks through hydraulic fracturing. This process not only consumes a large amount of water but also carries the risk of inducing microseismic events, posing challenges to the environment and safety, and severely restricting its widespread application. Therefore, the development of efficient and environmentally friendly new geothermal development technologies is particularly urgent. Summary of the Invention

[0004] The main objective of this invention is to propose a geothermal development system that couples compressed carbon dioxide energy storage, aiming to achieve efficient utilization of geothermal energy.

[0005] To achieve the above objectives, the geothermal development system with coupled compressed carbon dioxide energy storage proposed in this invention includes a first carbon dioxide storage tank, a second carbon dioxide storage tank, a compression system, a geothermal development well, a power generation system, and a thermal storage system. The development well extends into the hot dry rock and has an inner pipe and an outer pipe. Both ends of the inner pipe and the outer pipe are open. The outer pipe is sleeved on the inner pipe. The end of the inner pipe near the hot dry rock is connected to the end of the outer pipe near the hot dry rock. The compression system is connected to the outlet of the first carbon dioxide storage tank and the inlet of the second carbon dioxide storage tank. The outlet of the second carbon dioxide storage tank is connected to the end of the outer pipe away from the hot dry rock, and the end of the inner pipe away from the hot dry rock is connected to the inlet of the power generation system. The outlet of the power generation system is connected to the inlet of the first carbon dioxide storage tank. The thermal storage system is heat-exchange coupled to the compression system.

[0006] In one embodiment, an expansion section is formed at the end of the outer tube near the hot dry rock, and the inner diameter of the expansion section gradually increases from the end of the expansion section near the ground to the end of the expansion section away from the ground.

[0007] In one embodiment, the geothermal development well further includes a thermally conductive coating applied to the outer peripheral wall of the outer pipe at the end near the dry hot rock.

[0008] In one embodiment, the geothermal development well further includes a head, which is sealed over the inner pipe and the outer pipe. The head has an inlet for working fluid communicating with the outer pipe and an outlet for working fluid communicating with the inner pipe. The outlet of the second carbon dioxide storage tank is connected to the inlet for working fluid, and the outlet for working fluid is connected to the inlet of the power generation system.

[0009] In one embodiment, the geothermal development well further includes a cementing layer, which is sleeved on the outer pipe.

[0010] In one embodiment, the cementing layer near the end of the dry hot rock is a thermally conductive cement layer; The cementing layer at the end furthest from the hot dry rock is an insulating cement layer.

[0011] In one embodiment, the power generation system consists of an expander unit and a generator unit connected together, with the end of the inner pipe away from the hot dry rock connected to the inlet of the expander unit, and the outlet of the generator unit connected to the inlet of the first carbon dioxide storage tank.

[0012] In one embodiment, the geothermal development system with coupled compressed carbon dioxide energy storage further includes a working fluid pump located between the end of the outer pipe furthest from the hot dry rock and the outlet of the second carbon dioxide storage tank.

[0013] In one embodiment, the compression system includes a low-pressure compressor and a high-pressure compressor arranged in sequence, with the outlet of the first carbon dioxide storage tank connected to the inlet of the low-pressure compressor and the outlet of the high-pressure compressor connected to the inlet of the second carbon dioxide storage tank.

[0014] In the technical solution of this invention, when power generation is required, high-pressure, low-temperature carbon dioxide is released from the second carbon dioxide storage tank and enters the outer pipe of the geothermal development well through a pipeline. The carbon dioxide flows downward along the outer pipe, reaching the dry hot rock area at the bottom of the well, where it is heated by the high-temperature rock mass. The heated carbon dioxide flows from the bottom of the outer pipe into the inner pipe and returns upward along the inner pipe to the wellhead. The high-temperature, high-pressure carbon dioxide enters the power generation system to generate electricity. After power generation, the carbon dioxide pressure decreases, the temperature drops, and it enters the first carbon dioxide storage tank for storage. Then, it is compressed to a high-pressure state by the compression system and stored in the second carbon dioxide storage tank. By coupling carbon dioxide energy storage and geothermal development, the efficient utilization of geothermal energy is achieved. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 A schematic diagram of an embodiment of the geothermal development system with coupled compressed carbon dioxide energy storage provided by the present invention; Figure 2 This is a schematic diagram of the structure of an embodiment of a geothermal development well provided by the present invention; Figure 3 This is a cross-sectional view of an embodiment of a geothermal development well provided by the present invention.

[0017] Explanation of icon numbers: 1. First carbon dioxide storage tank; 2. Compression system; 3. Second carbon dioxide storage tank; 4. Geothermal development well; 4-1. Inner pipe; 4-2. Outer pipe; 4-3. Cementing layer; 4-4. Rock strata; 4-5. Head; 4-6. Thermal conductive coating; 5. Expander unit; 6. Generator unit; 7. Thermal storage system.

[0018] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0021] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0022] This invention proposes a geothermal development system that couples compressed carbon dioxide energy storage.

[0023] Please see Figure 1 , Figure 2 and Figure 3 In one embodiment of the present invention, the geothermal development system with coupled compressed carbon dioxide energy storage includes a first carbon dioxide storage tank 1, a second carbon dioxide storage tank 3, a compression system 2, a geothermal development well 4, a power generation system, and a thermal storage system 7. The geothermal development well 4 extends into the hot dry rock and has an inner pipe 4-1 and an outer pipe 4-2. Both ends of the inner pipe 4-1 and the outer pipe 4-2 are open. The outer pipe 4-2 is sleeved on the inner pipe 4-1. The end of the inner pipe 4-1 near the hot dry rock is connected to the end of the outer pipe 4-2 near the hot dry rock. The compression system 2 is connected to the outlet of the first carbon dioxide storage tank 1 and the inlet of the second carbon dioxide storage tank 3. The outlet of the second carbon dioxide storage tank 3 is connected to the end of the outer pipe 4-2 away from the hot dry rock. The end of the inner pipe 4-1 away from the hot dry rock is connected to the inlet of the power generation system. The outlet of the power generation system is connected to the inlet of the first carbon dioxide storage tank 1.

[0024] When the power grid is in a low-temperature period or when there is sufficient external power, the compression system 2 is activated, which consumes external power to compress the low-temperature, low-pressure carbon dioxide in the first carbon dioxide storage tank 1 into a high-pressure, low-temperature state and store it in the second carbon dioxide storage tank 3. At the same time, the heat of compression is stored in the heat storage system 7.

[0025] During peak electricity demand periods, the compression system 2 is shut down, and the high-pressure, low-temperature carbon dioxide from the second carbon dioxide storage tank 3 is injected into the geothermal development well 4 to absorb heat. After being converted into a high-temperature, high-pressure state, it drives the power generation system to generate electricity.

[0026] The geothermal development well 4 features a coaxial nested double-casing design. The inner pipe 4-1 is a straight pipe open at both ends, extending to the target dry hot rock layer at its bottom. The outer pipe 4-2 is fitted over the inner pipe 4-1, forming a sealed cavity with an open top, together with the bottom expansion section. A connecting structure is located at the bottom of the inner pipe 4-1, allowing the cavity of the inner pipe 4-1 to connect with the annular cavity of the outer pipe 4-2 through a radial through-hole, thus forming a working fluid circulation channel. The pipeline uses stainless steel pipes with a single length of not less than 10 meters, welded using laser seamless welding technology.

[0027] The connection between the second carbon dioxide storage tank 3 and the outer pipe 4-2 of the geothermal development well 4 facilitates the precise delivery of high-pressure but relatively low-temperature carbon dioxide to the dry hot rock reservoir. By utilizing the flow of carbon dioxide to absorb geothermal heat, the geothermal resources of the dry hot rock are fully exploited, and the utilization rate of geothermal energy is improved. Compared with traditional development methods, using carbon dioxide, a fluid with special thermophysical properties, reduces pumping energy consumption and saves energy and costs by utilizing its unique siphon effect. On the other hand, it is environmentally friendly and better matches the demand for carbon reduction in energy.

[0028] The thermal storage system 7 is heat-coupled with the compression system 2. The thermal storage system 7 mainly includes a plate heat exchanger, a cold water storage tank, and a hot water storage tank. The large amount of heat of compression generated during the operation of the compression system 2 is absorbed by the circulating water through the plate heat exchanger. Low-temperature water is pumped from the cold water storage tank, absorbs the heat of compression from carbon dioxide in the plate heat exchanger, and becomes high-temperature water, which is then stored in the hot water storage tank. When needed, the high-temperature water is pumped from the hot water storage tank for other uses, such as providing heat energy to surrounding facilities. This process avoids the waste of heat of compression, realizes the secondary utilization of thermal energy, significantly improves the overall energy utilization efficiency of the system, and reduces the system's operating costs.

[0029] In the technical solution of this invention, when power generation is required, high-pressure, low-temperature carbon dioxide is released from the second carbon dioxide storage tank 3 and enters the outer pipe 4-2 of the geothermal development well 4 through a pipeline. The carbon dioxide flows downward along the outer pipe 4-2, reaching the dry hot rock area at the bottom of the well, where it is heated by the high-temperature rock mass. The heated carbon dioxide flows from the bottom of the well through the outer pipe 4-2 into the inner pipe 4-1, and then returns upward along the inner pipe 4-1 to the wellhead. The high-temperature, high-pressure carbon dioxide enters the power generation system to generate electricity. After power generation, the carbon dioxide pressure decreases, the temperature drops, and it enters the first carbon dioxide storage tank 1 for storage. Then, it is compressed to a high-pressure state by the compression system 2 and stored in the second carbon dioxide storage tank 3. By coupling carbon dioxide energy storage and geothermal development, the efficient utilization of geothermal energy is achieved.

[0030] Furthermore, in one embodiment of the present invention, please refer to... Figure 2The outer pipe 4-2 has an expansion section at the end near the hot dry rock. The inner diameter of the expansion section gradually increases from the end near the ground to the end further away from the ground. That is, the end of the outer pipe 4-2 extending into the hot dry rock layer 4-4 is designed as a gradually expanding conical structure, with its inner diameter gradually increasing from the upper end near the ground to the lower end further away from the ground, forming a funnel-shaped opening; and the expansion section is completely embedded in the target hot dry rock reservoir. When high-pressure but relatively low-temperature carbon dioxide working fluid flows through the expansion section, the flow velocity of carbon dioxide decreases due to the increased flow cross-section. The low-velocity fluid can form large-scale vortices within the conical space, thereby prolonging the contact time with the rock mass and increasing the heat extraction power. Furthermore, the gradual increase in inner diameter provides sufficient space for the volume expansion of carbon dioxide, allowing the fluid to flow more uniformly within the expansion section, reducing unstable flow phenomena such as turbulence and eddies that may occur due to space constraints, thus reducing energy loss during the flow process.

[0031] To improve geothermal extraction efficiency, in one embodiment of the present invention, please refer to... Figure 2 The geothermal development well 4 also includes a thermally conductive coating 4-6, which is applied to the outer peripheral wall of the outer pipe 4-2 near the dry hot rock. The thermally conductive coating 4-6 is typically made of a material with high thermal conductivity, such as aluminum nitride (AlN) based composite ceramic material, doped with silicon carbide (SiC) nanoparticles to enhance thermal conductivity. The thermally conductive coating 4-6 can be formed into a dense bonding layer on the outer peripheral wall of the outer pipe 4-2 using plasma spraying technology, extending from the conical surface of the expansion section to the contact area with the dry hot rock layer 4-4. When high-pressure but relatively low-temperature carbon dioxide fluid is injected into the dry hot rock area, the thermally conductive coating 4-6 accelerates heat transfer between the outer pipe 4-2 and the surrounding dry hot rock. During the process of the carbon dioxide fluid absorbing heat from the dry hot rock, the presence of the thermally conductive coating 4-6 reduces thermal resistance, allowing heat to be transferred more quickly from the dry hot rock to the outer pipe 4-2, where it is then absorbed by the carbon dioxide fluid. This efficient heat transfer not only improves the extraction efficiency of geothermal energy but also allows the carbon dioxide to heat up more quickly, thereby improving the efficiency of the subsequent power generation system.

[0032] Specifically, in one embodiment of the present invention, please refer to... Figure 2The end cap 4-5 is a sealing cap located between the inner pipe 4-1 and the outer pipe 4-2. End cap 4-5 has an inlet for the working fluid connecting to the outer pipe 4-2 and an outlet for the working fluid connecting to the inner pipe 4-1. The outlet of the second carbon dioxide storage tank 3 connects to the inlet for the working fluid, and the outlet for the working fluid connects to the inlet of the power generation system. End cap 4-5 can be made of forged low-alloy steel and is sealed to the wellhead flange using high-strength bolts. The inlet of end cap 4-5 connects to the outer pipe 4-2, and the outlet for the working fluid connects to the inner pipe 4-1. This allows high-pressure but relatively low-temperature carbon dioxide to flow stably from the second carbon dioxide storage tank 3, enter the outer pipe 4-2 through the inlet, and then flow along the annular space between the outer pipe 4-2 and the inner pipe 4-1 towards the hot dry rock area. When the carbon dioxide fluid completes heat exchange in the hot dry rock area, absorbing heat and becoming high-temperature, high-pressure carbon dioxide, it will flow back to the surface through the inner pipe 4-1 and smoothly enter the power generation system through the outlet for the working fluid. During this process, the sealing performance of end cap 4-5 ensures airtightness.

[0033] Furthermore, in one embodiment of the present invention, please refer to... Figure 3 The geothermal development well 4 also includes a cementing layer 4-3, which is fitted onto the outer pipe 4-2. The cementing layer 4-3 is made of cement and is in direct contact with the rock strata 4-4. During the development of hot dry rock geothermal energy, the development well needs to withstand various stresses from the underground rock strata 4-4, including but not limited to formation pressure, rock expansion force, and additional stresses generated during high-pressure water or gas injection operations. The presence of the cementing layer 4-3 significantly enhances the structural strength of the outer pipe 4-2, enabling it to better withstand these complex external stresses.

[0034] Furthermore, in one embodiment of the present invention, the cementing layer 4-3 at the end closest to the hot dry rock is a thermally conductive cement layer; the cementing layer 4-3 at the end furthest from the hot dry rock is a thermally insulating cement layer. The thermally conductive cement layer is composed of silicate cement substrate mixed with highly thermally conductive fillers (such as graphite powder, silicon carbide, or metal powder), which can effectively reduce the thermal resistance between the cementing layer 4-3 and the surrounding hot dry rock, promote the efficient transfer of geothermal energy to the carbon dioxide working fluid flowing through the outer pipe 4-2, thereby significantly improving the heating rate and final temperature of carbon dioxide. The thermally insulating cement layer is composed of lightweight cement substrate (such as foamed cement or cenosphere cement) or mixed with highly efficient thermal insulation materials (such as aerogel or glass microspheres), which can effectively prevent the heated carbon dioxide from dissipating heat to the low-temperature formation during its upward flow, reduce system heat loss, and ensure that heat is retained to the maximum extent and carried into the power generation system.

[0035] Specifically, in one embodiment of the present invention, please refer to... Figure 1The power generation system consists of an expander unit 5 and a generator unit 6 connected together. The end of the inner pipe 4-1 furthest from the hot dry rock is connected to the inlet of the expander unit 5, and the outlet of the generator unit 6 is connected to the inlet of the first carbon dioxide storage tank 1. During system operation, heated carbon dioxide flows from the bottom of the outer pipe 4-2 into the inner pipe 4-1, and returns upwards to the wellhead along the inner pipe 4-1. The high-temperature, high-pressure carbon dioxide enters the expander unit 5. Inside the expander unit 5, the high-temperature, high-pressure carbon dioxide fluid expands and performs work, driving the impeller or piston and other mechanical components of the expander unit 5 to rotate, converting thermal energy into mechanical energy. During this process, the temperature and pressure of the carbon dioxide fluid decrease significantly, transforming into a low-temperature, low-pressure state. After the expander unit 5 completes its expansion work, the carbon dioxide fluid carries a certain amount of mechanical energy and flows out of the expander unit 5. At this time, the mechanical energy is transmitted to the generator unit 6 through a transmission device (such as a shaft or coupling) connected to the generator, driving the generator to operate and generate electricity. Subsequently, the carbon dioxide fluid flows into the first carbon dioxide storage tank 1, preparing for the next cycle. The expander unit 5 achieves effective conversion of geothermal energy by converting the thermal energy in the high-temperature, high-pressure carbon dioxide into mechanical energy. Specifically, expander unit 5 is a key component that utilizes high-temperature, high-pressure carbon dioxide fluid for expansion, converting thermal energy into mechanical energy. Expansion under high temperature and pressure improves the expander's efficiency, increases mechanical energy output, and thus enhances the overall system's energy conversion efficiency and power generation capacity. Generator unit 6 efficiently converts the mechanical energy output from expander unit 5 into electrical energy. This allows underground energy, originally existing as geothermal energy, to be converted into electricity—a more versatile and widely applicable energy form—significantly expanding the system's functionality and applicability in energy supply.

[0036] Furthermore, in one embodiment of the present invention, the geothermal development system coupled with compressed carbon dioxide energy storage also includes a working fluid pump, which is located between the end of the outer pipe 4-2 furthest from the dry hot rock and the outlet of the second carbon dioxide storage tank 3. The main function of the working fluid pump is to pressurize or regulate the carbon dioxide fluid, ensuring that it can enter the geothermal development well 4 at a stable flow rate and pressure for geothermal energy exchange. During system operation, the carbon dioxide fluid flows out from the second carbon dioxide storage tank 3. At this time, the working fluid pump pressurizes or regulates the carbon dioxide fluid to maintain its pressure at the ideal working pressure required for carbon dioxide circulation. The carbon dioxide fluid then enters the geothermal development well 4, where it exchanges geothermal energy. After being heated, the heated carbon dioxide fluid flows into the power generation system for the conversion of thermal energy into electrical energy. The pressurization and regulation of the carbon dioxide fluid by the working fluid pump ensures the initial pressure of the carbon dioxide entering the geothermal development well 4, so that the heated carbon dioxide enters the expander unit 5 with higher pressure and temperature, which allows the expander to expand and perform work under greater pressure and temperature differences. Improving the working efficiency of the expander increases mechanical energy output, thereby enhancing the energy conversion efficiency and power generation capacity of the entire system.

[0037] Specifically, in one embodiment of the present invention, the compression system 2 adopts a multi-stage compression system, including a low-pressure compressor and a high-pressure compressor arranged sequentially. The outlet of the first carbon dioxide storage tank 1 is connected to the inlet of the low-pressure compressor, and the outlet of the high-pressure compressor is connected to the inlet of the second carbon dioxide storage tank 3. The low-pressure compressor and the high-pressure compressor can perform staged compression. The carbon dioxide gas flowing out of the first carbon dioxide storage tank 1 first flows into the low-pressure compressor. At this time, the pressure of the carbon dioxide is relatively low, and the low-pressure compressor performs preliminary compression on the carbon dioxide, increasing its pressure. The carbon dioxide fluid after preliminary compression by the low-pressure compressor then enters the high-pressure compressor, which further increases the pressure of the carbon dioxide to meet the storage requirements of the second carbon dioxide storage tank 3. The high-pressure carbon dioxide fluid at the outlet of the high-pressure compressor flows into the second carbon dioxide storage tank 3 through a pipeline, completing the compression process. By sequentially setting the low-pressure compressor and the high-pressure compressor, the pressure of the carbon dioxide can be gradually increased, avoiding problems such as excessively high compression ratio, low compression efficiency, and severe equipment wear that may occur with single-stage compression. The low-pressure compressor and the high-pressure compressor each undertake different compression tasks, making the compression process more stable and efficient.

[0038] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A geothermal development system coupled with compressed carbon dioxide energy storage, characterized in that, It includes a first carbon dioxide storage tank, a second carbon dioxide storage tank, a compression system, a geothermal development well, a power generation system, and a thermal storage system; The geothermal development well extends into the dry hot rock and has an inner pipe and an outer pipe. Both ends of the inner pipe and the outer pipe are open. The outer pipe is sleeved on the inner pipe. The end of the inner pipe near the dry hot rock is connected to the end of the outer pipe near the dry hot rock. The compression system connects the outlet of the first carbon dioxide storage tank and the inlet of the second carbon dioxide storage tank. The outlet of the second carbon dioxide storage tank is connected to the end of the outer pipe away from the hot dry rock. The end of the inner pipe away from the hot dry rock is connected to the inlet of the power generation system. The outlet of the power generation system is connected to the inlet of the first carbon dioxide storage tank. The thermal storage system is heat-exchange coupled to the compression system.

2. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, An expansion section is formed at the end of the outer tube near the hot dry rock. The inner diameter of the expansion section gradually increases from the end of the expansion section near the ground to the end of the expansion section away from the ground.

3. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The geothermal development well also includes a thermally conductive coating, which is applied to the outer peripheral wall of the outer pipe at the end near the dry hot rock.

4. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The geothermal development well also includes a head, which is a sealing cover for the inner pipe and the outer pipe. The head has an inlet for working fluid connected to the outer pipe and an outlet for working fluid connected to the inner pipe. The outlet of the second carbon dioxide storage tank is connected to the inlet for working fluid, and the outlet for working fluid is connected to the inlet of the power generation system.

5. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The geothermal development well also includes a cementing layer, which is fitted onto the outer pipe.

6. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 5, characterized in that, The cementing layer near the end of the dry hot rock is a thermally conductive cement layer; The cementing layer at the end furthest from the hot dry rock is an insulating cement layer.

7. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The power generation system consists of an expander unit and a generator unit connected together. The end of the inner pipe away from the hot dry rock is connected to the inlet of the expander unit, and the outlet of the generator unit is connected to the inlet of the first carbon dioxide storage tank.

8. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The geothermal development system with coupled compressed carbon dioxide energy storage also includes a working fluid pump, which is located between the end of the outer pipe away from the dry hot rock and the outlet of the second carbon dioxide storage tank.

9. The geothermal development system with coupled compressed carbon dioxide energy storage as described in claim 1, characterized in that, The compression system includes a low-pressure compressor and a high-pressure compressor arranged in sequence. The outlet of the first carbon dioxide storage tank is connected to the inlet of the low-pressure compressor, and the outlet of the high-pressure compressor is connected to the inlet of the second carbon dioxide storage tank.

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