Geothermal power generation system
The geothermal power generation system recovers thermal energy by integrating thermoelectric modules with existing piping to generate additional electricity, addressing thermal energy waste and reducing infrastructure costs for remote monitoring.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- E THERMOGENTEK CO LTD
- Filing Date
- 2022-03-22
- Publication Date
- 2026-05-20
AI Technical Summary
Conventional geothermal power generation systems waste significant thermal energy by returning unused hot water to the ground, and the thermal energy of old production wells is not effectively utilized, while the cost of supplying power to remote monitoring equipment is high due to the need for long-distance power cables.
A geothermal power generation system with a thermoelectric power generation module installed around the injection well that utilizes the temperature difference between hot water and ambient or groundwater temperatures to generate additional electricity, integrating with existing piping to minimize costs and installation complexity.
The system effectively recovers unused thermal energy for self-sustaining power supply, reducing the need for new infrastructure and enabling efficient monitoring and maintenance of geothermal facilities without long-distance power cables.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a geothermal power generation system that recovers electric power using thermal energy not utilized in geothermal power generation.
Background Art
[0002] In modern industrial society, particularly centered around factories, power plants, steel mills, automobiles, buildings, lighting, ships, etc., an enormous amount of waste heat, more than 60% of the total primary energy supply, is discharged into the global environment. Therefore, from the perspective of global environmental protection, reduction of waste heat, energy conservation, or utilization of natural energy, etc. are desired. Examples of utilization of natural energy include solar power generation, wind power generation, geothermal power generation, etc.
[0003] As shown in FIG. 9, a conventional geothermal power generation system pumps high-temperature spring water from an underground geothermal spring source 101 through a production well 102, separates it into high-temperature steam 104 and hot water 105 by a steam-water separator 103, and drives a steam turbine 106 using the separated high-temperature steam 104 to generate electricity with a generator 107. The hot water 105 is collected together with the hot water 110 that exits from the condenser 108 of the steam turbine 106 and returned to the ground through a reinjection well 109 so that the geothermal spring source 101 does not dry up (for example, Patent Document 1).
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0005] In conventional geothermal power generation systems, steam from geothermal sources is used in a steam turbine generator to convert it into electrical energy, but the remaining hot water is returned to the ground through injection wells. The amount of thermal energy is enormous, and it is possible to utilize a portion of this thermal energy as long as it does not adversely affect the temperature of the underground geothermal reservoir where the hot water is returned, but until now, such utilization has not been done at all.
[0006] Furthermore, when the amount of steam emitted during the operation of a geothermal power generation system decreases, new wells are drilled to compensate for the production wells, but the thermal energy of the remaining old production wells was not being effectively utilized.
[0007] Furthermore, geothermal power plants are often located in mountainous areas. Therefore, it is necessary to supply power to lighting, surveillance cameras, wireless sensors, etc., in order to monitor piping and equipment, or to monitor the temperature and flow rate of high-temperature steam and hot water. However, this requires laying long-distance power cables, incurring enormous costs, which has been a major obstacle to improving equipment monitoring and maintenance.
[0008] This invention has been made in view of the above, and its main objective is to provide a geothermal power generation system equipped with an independent power supply system that can easily recover electricity using thermal energy that is not utilized in geothermal power generation. [Means for solving the problem]
[0009] The geothermal power generation system according to the present invention is a geothermal power generation system that generates electricity by separating high-temperature hot spring water pumped up from a geothermal spring source in a production well into high-temperature steam and hot water in a steam-water separator, and using the high-temperature steam separated in the steam-water separator to drive a steam turbine, and returns the separated hot water to the ground via an injection well, and a thermoelectric power generation module is installed around the pipes constituting the injection well, and the thermoelectric power generation module uses the hot water as a high-temperature source and the ambient temperature of the thermoelectric power generation module as a low-temperature source, and generates thermoelectric power from the temperature difference between the two. [Effects of the Invention]
[0010] According to the present invention, it is possible to provide a geothermal power generation system equipped with an independent power supply system that can easily recover electricity using thermal energy that is not utilized in geothermal power generation. [Brief explanation of the drawing]
[0011] [Figure 1] This diagram schematically shows the configuration of a geothermal power generation system in one embodiment of the present invention. [Figure 2] This is a magnified view of the injection well in the region indicated by A in Figure 1. [Figure 3] This diagram shows a configuration in which thermoelectric power generation modules are mounted around the pipes that make up the injection well. [Figure 4] This diagram shows the configuration of an injection well when using a groundwater source as a low-temperature source for a thermoelectric power generation module. [Figure 5] This is a cross-sectional view along the VV line in Figure 4. [Figure 6] This diagram shows the configuration of an injection well when using air as the low-temperature source for a thermoelectric power generation module. [Figure 7] This is a cross-sectional view along line VII-VII in Figure 6. [Figure 8] This diagram shows the specific configuration of a thermoelectric power generation module. [Figure 9] This diagram shows the configuration of a conventional geothermal power generation system. [Modes for carrying out the invention]
[0012] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is not limited to the following embodiments. Furthermore, modifications can be made as appropriate without departing from the scope of achieving the effects of the present invention.
[0013] Figure 1 is a schematic diagram showing the configuration of a geothermal power generation system in one embodiment of the present invention.
[0014] As shown in FIG. 1, in the geothermal power generation system 50 of this embodiment, the high-temperature spring water pumped up from the geothermal spring source 1 by the production well 2 is separated by the gas-liquid separator 3 into high-temperature steam 4 and hot water 5, and the separated high-temperature steam 4 is used to drive the steam turbine 6, thereby generating electricity with the generator 7. On the other hand, the hot water 5 separated by the gas-liquid separator 3 is collected together with the hot water 10 coming out of the condenser 8 of the steam turbine 6 and returned to the ground 90 through the reinjection well 9.
[0015] FIG. 2 is an enlarged view of the reinjection well 9 in the area indicated by A in FIG. 1.
[0016] As shown in FIG. 2, a thermoelectric power generation module 30 is mounted around the pipe 20 constituting the reinjection well 9. As shown in FIG. 1, the reinjection well 9 is embedded in the ground 90, and the thermoelectric power generation module 30 uses the hot water 5 as a high-temperature source and the ambient temperature (ground temperature) around the thermoelectric power generation module 30 as a low-temperature source, and thermoelectric power generation is performed due to the temperature difference between the two.
[0017] In this embodiment, in order to protect the thermoelectric power generation module 30 and reduce the heat transfer loss to the ground temperature which is the low-temperature source, and to ensure a large temperature difference in the thermoelectric power generation module 30, it is preferable to closely attach a heat dissipation and waterproof sheet with high thermal conductivity to the outside of the thermoelectric power generation module 30.
[0018] Also, as shown in FIG. 3, after mounting a heat dissipation sheet (not shown) with high thermal conductivity on the outside of the thermoelectric power generation module 30, further, a metal outer pipe cover 40 may be closely attached to the outside of the heat dissipation sheet and mounted. Thereby, the protection of the thermoelectric power generation module 30 can be made stronger. Also, it is preferable to provide welding or a seal 41 at both ends of the outer pipe cover 40 to protect the thermoelectric power generation module 30.
[0019] With such a configuration, during the operation of the geothermal power generation system 50, as hot water 5 flows through the pipe 20 of the injection well 9, the outer diameter of the pipe 20 thermally expands. As a result, good adhesion can be obtained between the thermoelectric power generation module 30, the pipe 20, and the outer pipe cover 40, so that high output can be stably obtained.
[0020] In the above embodiment, an example using the ground temperature as the low-temperature source around the thermoelectric power generation module 30 has been described. However, a groundwater source may be used as the low-temperature source.
[0021] FIG. 4 is a diagram showing the configuration of the injection well 9 when a groundwater source is used as the low-temperature source of the thermoelectric power generation module 30, and FIG. 5 is a cross-sectional view taken along the line V-V of FIG. 4.
[0022] As shown in FIGS. 4 and 5, the outside of the outer pipe cover 40 shown in FIG. 3 is further covered with a metal casing pipe 45, and a groundwater source 60 serving as a low-temperature source flows between the outer pipe cover 40 and the casing pipe 45. With such a configuration, since the groundwater source has a low temperature, is constant, and has a large heat capacity, stable and efficient power generation becomes possible. Note that it is preferable to use a casing pipe 45 with openings in order to improve the flow of the groundwater source 60.
[0023] Also, in the above embodiment, an example in which the thermoelectric power generation module 30 is mounted around the injection well 9 in the portion buried in the ground 90 has been shown. However, the thermoelectric power generation module 30 may be mounted around the injection well 9 in the portion exposed on the ground. In this case, the atmosphere becomes the low-temperature source of the thermoelectric power generation module 30.
[0024] FIG. 6 is a diagram showing the configuration of the injection well 9 when the atmosphere is used as the low-temperature source of the thermoelectric power generation module 30, and FIG. 7 is a cross-sectional view taken along the line VII-VII of FIG. 6.
[0025] As shown in Figures 6 and 7, heat dissipation fins 70 are provided on the outside of the thermoelectric power generation module 30. This allows the atmospheric side of the thermoelectric power generation module 30 to be air-cooled, creating a temperature difference within the module, which enables it to generate electricity at a high output.
[0026] According to this embodiment, by attaching a thermoelectric power generation module 30 around the pipe 20 that constitutes the injection well 9, a geothermal power generation system equipped with a self-sustaining power supply system that can easily recover electricity using thermal energy not utilized in geothermal power generation can be realized.
[0027] The geothermal power generation system in this embodiment can generate electricity using the existing piping (pipe 20) of the geothermal power plant, thus minimizing the cost of new equipment. In addition, it is easy to install, compact, requires no maintenance on the system itself, and realizes a self-sustaining power system with a high cost-performance ratio.
[0028] Furthermore, since a self-sustaining power system can be realized simply by attaching thermoelectric power generation modules 30 around the pipes 20 that make up the injection well 9, the thermal energy of the old pile well can also be utilized in a simple and effective manner.
[0029] Furthermore, the electricity generated by the self-sustaining power system can not only be used as auxiliary power for geothermal power plants, but also as a self-sustaining power source for lighting, surveillance cameras, and wireless sensors such as temperature and flow rate sensors in the vicinity of the installation site. This eliminates the need to lay new, long-distance power cables to geothermal power plants on vast sites, enabling monitoring and sensing of piping and other systems at minimal cost.
[0030] Furthermore, the self-sustaining power system in this embodiment has a structure in which the thermoelectric power generation module 30 is wrapped around the outer circumference of existing piping, and since there are no structures inside the piping, conventional scale removal methods such as pH adjustment can be used as is, making scale removal easy. In other words, a self-sustaining power system utilizing unused waste heat can be realized easily and at low cost without providing any new structures other than the thermoelectric power generation module 30 or using any new means.
[0031] (Specific configuration of the thermoelectric power generation module) Figure 8 shows the specific configuration of the thermoelectric power generation module 30. As shown in Figure 8, P-type thermoelectric elements 33 and N-type thermoelectric elements 34 are mounted alternately on wiring lands 32 formed on a flexible base substrate 31. The P-type thermoelectric elements 33 and N-type thermoelectric elements 34 are connected in series by a wiring layer 36 formed on a flexible upper wiring substrate 35. The power generated by thermoelectric power is extracted from the extraction electrode 37. In this figure, the flexible upper wiring substrate 35 is made transparent so that the chip mounting and wiring on the lower side can be seen.
[0032] The upper wiring board 35 has slits 38 formed between the connection rows of the P-type thermoelectric element 33 and the N-type thermoelectric element 34. This makes it easier for the thermoelectric power generation module 30 to bend perpendicular to the slits 38, and by aligning the slits 38 with the pipe axis direction, it becomes easier for the module to make close contact with the pipe 20 of the injection well 9.
[0033] Furthermore, in order to reduce heat transfer loss between the thermoelectric power generation module 30 and the pipe 20 of the injection well 9, and to ensure a large temperature difference in the thermoelectric power generation module 30, it is preferable to insert a heat dissipation sheet with high thermal conductivity between the pipe 20 of the injection well 9 and the thermoelectric power generation module 30.
[0034] The thermoelectric power generation module 30 is, for example, 50 mm square, and consists of 260 pairs of P-type thermoelectric elements 33 made of BiSbTe, each 1.4 mm square and 2 mm high, and N-type thermoelectric elements 34 made of BiTe, connected in series. The pipe 20 of the injection well 9 has a nominal diameter of 600A (outer diameter 609 mm), and when the temperature of the hot water 5 is 150°C, the flow rate of the hot water 5 is 10 t / hour, and the groundwater temperature is 15°C, approximately 300 W of power generation is possible when 28 thermoelectric power generation modules 30 are wrapped around the outer diameter of the pipe 20 and 14 modules are installed along the length of 700 mm. [Explanation of Symbols]
[0035] 1 Geothermal spring source 2 Production wells 3 Steam water separator 4. High-temperature steam 5 Hot water 6. Steam Turbine 7. Generator 8. Condenser 9 Reinforcement well 10 Hot water 20 pipes 30 Thermoelectric Power Generation Modules 31 Base board 32 Wiring pads 33 P-type thermoelectric element 34 N-type thermoelectric element 35 Upper wiring board 36 wiring layer 37 electrode 38 slits 40 Outer tube cover 41 stickers 45 Casing pipe 50 Geothermal power generation systems 60 Groundwater sources 70 heat dissipation fins 80 Atmosphere 90 underground 101 Geothermal spring source 102 production wells 103 Steam water separator 104 High-temperature steam 105 Hot water 106 Steam Turbine 107 Generator 110 Hot water
Claims
1. A geothermal power generation system that generates electricity by pumping high-temperature hot spring water from a geothermal source through a production well, separating it into high-temperature steam and hot water using a steam-water separator, and using the separated high-temperature steam to drive a steam turbine, and a geothermal power generation system that returns to The hot water separated by the steam-water separator is returned to the ground via the reinjection well. Thermoelectric power generation modules are mounted around the pipes that make up the injection well. The thermoelectric power generation module uses the hot water as a high-temperature source and the ambient temperature around the thermoelectric power generation module as a low-temperature source, and generates thermoelectric power through the temperature difference between the two. The thermoelectric power generation module is mounted around the pipe buried underground, forming a geothermal power generation system.
2. The geothermal power generation system according to claim 1, wherein the low-temperature source is ground temperature or groundwater.
3. The geothermal power generation system according to claim 1, wherein the thermoelectric power generation module is flexible and is attached in close contact with the periphery of the pipe.
4. The geothermal power generation system according to claim 1, wherein an outer tube cover is attached to the outside of the thermoelectric power generation module.
5. The geothermal power generation system according to claim 1, wherein high thermal conductivity sheets are attached to the inside and outside of the thermoelectric power generation module.