Power generation system, power generation method, and hydrogen production method using the same

Abstract

To provide a power generation system and a power generation method capable of generating power stably over a long period of time while suppressing an excavation cost by using a geothermal resource in a non-volcanic area in a power plant in an ocean earth crust below a sea bottom without depending on volcanic magma, and to provide a hydrogen manufacturing method using the power generation system and the power generation method.SOLUTION: A power generation system includes: a power plant provided in an ocean earth crust; a heat medium pipe for transmitting earth crust heat from a non-volcanic deep layer earth crust heat region toward the power plant through a heat medium; and a plurality of heat storage chambers provided at positions whose depths from the power plant are different from each other for relaying the heat medium pipe. Power is generated at the power plant using earth crust heat transmitted through the plurality of heat storage chambers by a temperature difference power generation system or a turbine system.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power generation system and method that utilizes geothermal resources in non-volcanic regions, and a method for producing hydrogen using the same. [Background technology]

[0002] General geothermal power generation is known to generate electricity using turbines (Patent Document 1), and high-temperature steam generated when volcanic lava magma comes into contact with water is led to a power plant, where electricity is generated using turbines. This type of power generation using magma-water vapor is also based on valuable natural energy, but it is small in scale and is unlikely to become a core technology for large-scale power generation businesses. In addition, because magma can move, it is difficult to expect a long-term stable power generation business.

[0003] In addition, a power generating element is known that does not use a turbine, but has two types of materials that have the Seebeck effect, with one end serving as the high-temperature side and the other end serving as the low-temperature side, and generates electricity using the temperature difference between the two (Non-Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6587118 [Non-patent literature]

[0005] [Non-Patent Document 1] January 13, 2021 Journal of physics D;Applied physics pp.115503 Mixed‐Phase effect of the high Seebeck coefficient and low electricalResistivity in the Ag2S [Non-Patent Document 2] August 21, 2019, Nikkei Newspaper NEDO, Aisin Seiki, and Ibaraki University announced that they have succeeded in developing a technology that uses only common materials to generate electricity using slight temperature differences such as body heat. Made of iron, aluminum, and silicon, it does not contain rare or toxic elements like conventional materials, and material costs can be reduced to less than one-fifth. Summary of the Invention [Problem to be solved by the invention]

[0006] Conventional geothermal power generation has various limitations, and can only be expected to generate electricity on a small scale. In addition, because it relies on volcanic magma, which is easy to move, it is not possible to expect stable long-term business viability. Furthermore, there is always the risk of not knowing in advance whether steam will be produced when developing new facilities.

[0007] The object of the present invention is to provide a power generation system and method that does not rely on volcanic magma, but utilizes geothermal resources in non-volcanic regions in power plants in the oceanic crust below the seafloor, thereby reducing drilling costs and enabling stable power generation over the long term, as well as a method for producing hydrogen using the same. [Means for solving the problem]

[0008] In order to achieve the above object, the power generation system of the present invention comprises a power plant installed in the ocean crust, a heat medium pipe for transmitting geothermal heat from a non-volcanic deep geothermal heat region to the power plant via a heat medium, heat storage chambers installed on each floor at different depths from the power plant, and a piping unit installed on each floor and connected to the heat medium pipe and the heat storage chamber, wherein a space in which a first heat medium as the heat medium rising from a lower floor exists, and a space in which a second heat medium which has reached the power plant and descended from an upper floor and has a lower temperature than the first heat medium exists, are separately arranged adjacent to each other in the heat medium pipe and the piping unit, thereby suppressing heat loss due to heat transfer, and the geothermal heat which has passed through the multiple heat storage chambers is used to generate electricity in the power plant by a temperature difference power generation method or a turbine method. Release Power System The heat transfer pipe has a space in which the first heat transfer medium exists and a space in which the second heat transfer medium exists, the space being separated at a central portion and a peripheral portion in a cross section of the heat transfer pipe, and the piping unit has a space in which the first heat transfer medium exists and a space in which the second heat transfer medium exists, the space being separated in a vertical direction. It is characterized by:

[0009] The power generation method according to the present invention includes a first step of installing a power plant in the ocean crust, a heat transfer pipe for transferring geothermal heat from a non-volcanic deep geothermal heat region to the power plant via a heat transfer medium, heat storage chambers provided on each floor at different depths from the power plant, and a piping unit provided on each floor and connected to the heat transfer pipe and the heat storage chamber; and a second step of separately arranging a space in which a first heat transfer medium as the heat transfer medium rising from a lower floor exists, and a space in which a second heat transfer medium that reaches the power plant and descends from an upper floor exists, the second heat transfer medium being lower in temperature than the first heat transfer medium, adjacent to each other in the heat transfer pipe and the piping unit, thereby suppressing heat loss through heat transfer, and generating power in the power plant using a temperature difference power generation method or a turbine method using the geothermal heat that has passed through the multiple heat storage chambers. Release electric method And, The heat transfer medium pipe has a space in which the first heat transfer medium exists and a space in which the second heat transfer medium exists separated at a central portion and a peripheral portion in a cross section of the heat transfer medium pipe, and the piping unit has a space in which the first heat transfer medium exists and a space in which the second heat transfer medium exists separated in a vertical direction. It is characterized by:

[0010] A method for producing hydrogen according to the present invention is characterized in that hydrogen is produced by using power generated by the above-mentioned power generation method. Effect of the Invention

[0011] According to the present invention, by utilizing geothermal resources in non-volcanic regions in power plants located in the ocean crust beneath the seafloor, rather than relying on volcanic magma, it is possible to reduce drilling costs and generate stable electricity for the long term.

[0012] The power generated by this method can be used not only to generate electricity but also to generate hydrogen. The scope of the rights of the present invention covers not only the power generation system and the power generation method, but also the electricity itself which is the result of the power generation method, and the hydrogen itself which is the result of the method for producing hydrogen using the power generated by the power generation method. [Brief description of the drawings]

[0013] [Figure 1]FIG. 1 is an explanatory diagram showing a power plant provided in the ocean crust in a power generation system according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a schematic diagram showing a drilling method for implementing a power generation system and a power generation method according to an embodiment of the present invention; [Diagram 3] Overall concept diagram of a power plant using deep geothermal heat located on land (above ground) rather than in the ocean crust [Figure 4] (a) is a diagram explaining the drawing of the heat transfer pipe into the heat storage chamber via the satellite shaft and the connection of the heat transfer pipe via the piping unit, and (b) is a diagram showing the relationship between the heat storage chamber and the satellite shaft. [Diagram 5] (a) is an explanatory diagram of how the folded heat transfer pipe is installed in the heat storage chamber, (b) is a diagram of the relationship between the heat storage chamber and the heat transfer pipe, and (c) is a diagram of the heat storage chamber structure. [Figure 6] An explanatory diagram of the lowest heat transfer pipe that uses a heat transfer medium in a gaseous state [Figure 7] (a) is an explanatory diagram showing the cross-sectional configuration of the heat transfer pipe and the configuration of the bottom layer, and (b) is a diagram showing the flow of the heat transfer medium between adjacent layers in the depth direction. [Figure 8] An explanatory diagram of a worker room equipped with air conditioning equipment and a work equipment room equipped with cooling equipment [Figure 9] (a) is an explanatory diagram of the shaft being excavated, and (b) is an explanatory diagram of the discharge of soil from the shaft excavation. [Figure 10] (a) is an image of the assembly site for long heat transfer pipes, (b) is a diagram showing how the heat transfer pipes are transported underground using large flanges to bundle the heat transfer pipes, and (c) is a diagram showing the size of the large flanges. [Figure 11] (a) is an explanatory diagram of the connecting shaft that connects the center shaft and the satellite shaft, and (b) is an AA view of the connecting shaft. [Figure 12] Conceptual image of the thermoelectric power generation element unit being loaded onto a trolley and stored in the tunnel [Figure 13] (a) is an image of a huge power plant in which multiple thermoelectric generating element units are stacked inside each tunnel, and (b) is a diagram explaining the role of the side tracks on each floor. [Figure 14](a) is a diagram showing an image of an element board equipped with multiple thermoelectric generating elements for temperature difference power generation and how to make it, and (b) is an explanatory diagram showing the one-dimensional arrangement of thermoelectric generating elements. [Figure 15] (a) is an explanatory diagram of the two-dimensional arrangement of thermoelectric generation elements, and (b) is an image of the intersection of the element board, heat transfer pipes, and cold water pipes. [Figure 16] (a) is a diagram showing an experimental method and circuit for measuring the amount of power generated by a thermoelectric generating element, and (b) is a diagram showing the experimental results. [Figure 17] Diagram of an elevator in an elevator shaft [Figure 18] FIG. 13 is an explanatory diagram of a vertical shaft to be excavated in the second embodiment. [Figure 19] 13A, 13B, and 13C are explanatory diagrams respectively showing the arrangement of a heat transfer pipe, a heat transfer pipe unit, and a heat transfer pipe group in a satellite shaft according to a third embodiment; [Figure 20] FIG. 13 is an explanatory diagram of a small flange in the third embodiment. [Figure 21] 1A, 1B, and 1C are a plan view, a vertical cross-sectional view, and a perspective view, respectively, of a piping unit according to a third embodiment. [Figure 22] AA view of the connecting shaft in the third embodiment [Figure 23] 13A and 13B are explanatory diagrams of a dome-shaped power station according to a fourth embodiment. [Figure 24] A diagram showing the exchange of heat between a high-temperature heat medium α and a low-temperature heat medium β in a heat storage chamber. [Diagram 25] Block diagram of a turbine-based power generation system that uses geothermal heat from non-volcanic deep crustal heat fields [Figure 26] Block diagram of hydrogen production using power generation using deep crustal heat DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] (First embodiment) (Power Plant) 1 shows a power plant 9 as a geothermal power plant provided in the ocean crust in a power generation system according to an embodiment of the present invention. The power plant 9 is provided on a power plant level 10 in the ocean crust below the seafloor (more preferably in the ocean crust in a coastal area).

[0016] The continental crust is 30-50 km thick, while the oceanic crust is only 5-10 km thick. More specifically, in the ocean, sedimentary layers, andesite layers, and the upper mantle are integrated and move slowly as continental plates. The andesite layer is only 5-10 km thick, and the upper mantle is already below it. The upper mantle is made of peridotite.

[0017] The lower mantle is softened by crustal heat and, although solid, moves slowly through convection, whereas the upper mantle is tightly bound to the andesite layer just above and is an extremely stable part (asthenosphere).

[0018] Both andesite and peridotite layers are dense, sturdy, and have high thermal conductivity. Therefore, even if the excavation depth is small, the desired high temperature zone (400-500°C) can be reached quickly. In other words, the vertical thermal gradient is high, and the geothermal heat increases the more you dig, so a high temperature zone can be reached at a much shallower depth than if you were to dig on the land side (land area) as shown in Figure 3. In other words, in Figure 1, the height position of the excavation start surface relative to the deep crustal high temperature zone 1 can be lowered compared to Figure 3. This is expected to reduce excavation costs.

[0019] More specifically, by drilling shorter shafts (center shaft 11, satellite shaft 12, elevator shaft 13) each with a diameter of 8 m as shown in Figure 2 from the power plant floor (within the oceanic crust) 10, the cost of providing geothermal heat to the power plant 9 can be reduced.

[0020] The power plant 9 is constructed by connecting about 10 units, each having a base of 3500 square meters and a height of 30 meters, on the XY plane, as shown in FIG.

[0021] In FIG. 1, the power station 9 is connected to the land side through a tunnel T that slopes diagonally downward at a predetermined angle. That is, a road is formed by digging a tunnel T from a mountain near the coast to reach the power station.

[0022] More specifically, digging will start in the mountains near the coast, and tunnel T will be dug about 10 km long at an incline of about 1 degree from the land side to the materials factory just before power plant 9 via a rotary, and power plant 9 will be set up on power plant floor (inside the ocean crust) 10. At the materials factory, all materials to be used in this project will be stockpiled, including the processing plant.

[0023] In Figure 1, the materials factory and the power plant 9 are at the same height (horizontal), but it is also possible to have a tunnel T connecting the materials factory and the power plant 9 at the same slope as the slope from the land side to the materials factory.

[0024] In Fig. 1, 1 is the deep crustal high temperature zone, 3 is the heat storage chamber, and 4 is the thermoelectric power generation element unit. Also, 20 is a heat transfer pipe, which is cut to a specified length at the material factory.

[0025] In this embodiment, the land side and the power plant construction site are connected by land via tunnel T, so that the removed soil can be transported by large dump trucks or trucks (even unmanned transport) that pass through tunnel T. In other words, the large amount of removed soil can be transported unmanned and transported in a piston-like manner to the landfill site to be set up in the mountains.

[0026] In addition, by burying the waste soil in a new soil storage facility to be built in the nearby mountains, it will be possible to significantly reduce the transportation costs associated with removing the soil.

[0027] If the power plant 9 can be located near a city, the transmission loss can be significantly reduced. Furthermore, the transmission loss can be minimized by digging a tunnel from the power plant to the nearest substation and installing the transmission facilities there. For example, if the substation is installed below the power plant at a depth of 200 to 400 meters underground, the transmission loss can be significantly reduced.

[0028] In this way, when a power plant is built under the seabed near a coastal area close to a demand area, transmission losses can be reduced compared to the current case where power plants are built far away from demand areas. It also avoids the huge expenses for maintaining and maintaining the power grid. Furthermore, it also avoids the need for excessive equipment specifications to prevent sudden power outages caused by lightning, typhoons, salt damage, etc. Another advantage is that while a large space is required above ground, the land cost is huge, there is no land cost for underground construction.

[0029] Here, in such non-volcanic regions, it is thought that the temperature rises by about 30°C for every 1 km of depth, and if the ocean floor is 10°C and the power plant level (inside the ocean crust) 10 is located 0.1 km (100 m) to 0.2 km (200 m) from the ocean floor, the temperature at the power plant level (inside the ocean crust) 10 is thought to be around 13°C to 16°C.

[0030] When the power plant 9 is provided in the ocean crust in a coastal area, it is preferable to provide the substation below the power plant 9 at a depth of 200 to 400 m underground as described above, since this prevents the temperature from becoming too high.

[0031] (Utilization of deep crustal heat using heat transfer pipes) 1)Heating medium pipe The excavation method for realizing the power generation system (power generation device) and the power generation method according to the embodiment of the present invention will be described later with reference to Figures 2, 9, 10, and 11, but first, an overall image including the purpose of excavation will be described with reference to Figure 1. Then, the heat storage chamber installed on the work floor surface of each floor will be described with reference to Figures 4 to 6, the heat transfer pipes with reference to Figure 7, and the worker room and work equipment room installed on the work floor surface of each floor with reference to Figure 8.

[0032] Here, the heat transfer pipe refers to a pipe for transmitting geothermal heat from a deep geothermal heat region toward the power plant floor (inside the ocean crust) 10 via a heat transfer medium.

[0033] In both Figure 3 and Figure 1, the heat source is not volcanic magma but deep crustal thermal fields, and electricity is generated by utilizing the heat generated when radioactive isotopes in the Earth's outer core decay, which flows through the mantle and crust as conductive heat, or more preferably, by temperature difference electricity generation (using the Seebeck effect).

[0034] The heat from the deep earth's high temperature zone 1 is drawn up to the power plant via a heat transfer medium as a fluid (drawn up by a pump) that moves inside a heat transfer pipe 20 located close to the deep earth's high temperature zone 1, and is used for power generation. A preferable specific example of power generation is temperature difference power generation, and the heat from the deep earth's high temperature zone 1 is provided to the high temperature side of the temperature difference power generation.

[0035] 2) Heat storage chambers installed on each work floor surface with different depths Here, the heat medium pipe 20 connects the heat storage chambers 3 provided at every depth of 200 to 500 m (FIG. 4(b)). The reason for connecting the heat medium pipe 20 at each heat storage chamber 3 is that if the length of the heat medium pipe 20 becomes longer than a predetermined value, the pressure of the heat medium inside the heat medium pipe 20 increases and the heat medium pipe 20 will burst. To avoid this, the length of the heat medium pipe 30 is set so as to connect the heat storage chambers 3 provided at every depth of 200 to 500 m.

[0036] Then, by pulling a heat transfer pipe 20 from the power plant floor (inside the ocean crust) 10 to the heat storage chamber 3 at the closest depth to the power plant floor (inside the ocean crust) 10 through a vertical shaft (Figures 9 to 11) described later, it becomes possible to pull up deep crustal heat from the heat storage chamber 3 at the closest depth to the power plant floor (inside the ocean crust) 10 to the power plant floor.

[0037] Similarly, by pulling a heat transfer pipe 20 from the power plant floor (inside the ocean crust) 10 to the heat storage chamber 3 on the floor below via a vertical shaft (Figures 9 to 11) described later, it becomes possible to raise deep crustal heat from the heat storage chamber 3 on the lower floor through the heat storage chamber on the upper floor (the heat storage chamber at the depth closest to the power plant floor (inside the ocean crust) 10).

[0038] In this way, by pulling the heat transfer pipes 20 from the power plant floor (inside the ocean crust) 10 through the vertical shafts (Figures 9 to 11) described below to the heat storage chambers 3 (Figure 4(b)) on each floor, it is possible to raise deep crustal heat to the power plant floor (inside the ocean crust) 10 through the heat storage chambers 3 on each floor.

[0039] The heat transfer pipe 20 from the heat storage chamber 3 located at the deepest position on the power plant floor (in the ocean crust) 10 extends to near the deep crust region, making it possible to raise deep crustal heat from the power plant floor (in the ocean crust) 10 to the heat storage chamber 3 located at the deepest position. In this way, the deep crustal heat is raised to the power plant via each heat storage chamber 3.

[0040] Inside each heat storage chamber 3, as shown in FIG. 24, efficient heat exchange takes place between the high-temperature heat medium α (moved by pump P on the left side of the figure) and the low-temperature (low-temperature) heat medium β (moved by pump P on the right side of the figure), thereby reducing heat loss.

[0041] Fig. 5(a) is an explanatory diagram of the installation of the folded heat transfer pipe 38 into the heat storage chamber through the horizontally long hole 39 in the material factory (Fig. 1) on the power plant floor. Inside the heat storage chamber 3, a total of 80 pipes are installed, including 40 heat transfer pipes A arranged vertically in the horizontal plane and 40 heat transfer pipes B arranged horizontally in the horizontal plane.

[0042] Fig. 5(b) shows the inside of the heat storage chamber 3, and also shows that the heat medium in each heat medium pipe 20 is drawn up to the heat storage chamber 3 on the upper floor by a pump P. As a driving source for operating the pump P, for example, a Stirling engine (described later with reference to Fig. 17) can be used.

[0043] The heat storage chamber 3 shown in Figure 5 (c) is made of blocks of heat storage bricks (heat-resistant bricks containing a material that increases the specific heat) stacked in multiple layers as a lower layer, middle layer, and upper layer, with insulation material provided in the lower and upper layers, and a first group of heat transfer pipes (heat transfer pipes A 28) and a second group of heat transfer pipes (heat transfer pipes B 29) are stacked alternately so as to cross (orthogonally cross) each other through holes provided in the blocks in the middle layer.

[0044] The heat storage chambers 3 on each floor are assembled on the power plant floor (inside the ocean crust) 10, and are lowered to each floor from the elevator shaft 13 and moved laterally to be installed on the work floor of each floor. Then, on each floor, the heat storage chambers 3 are connected to a piping unit 100 (FIG. 4(a)) which will be described later.

[0045] Regarding the more specific assembly of the heat storage chamber 3, a large number of cubic blocks of heat storage bricks, each 2 m long, wide, and high, are fabricated on the power plant floor (inside the ocean crust) 10, and oblong holes for the heat transfer pipes are drilled in the side walls of the blocks. The blocks are then lifted horizontally by a forklift and stacked.

[0046] The lower floors of the block (e.g., the first and second floors) are filled with insulation material, and on the middle floors (e.g., the third to sixth floors), the heat transfer pipes 38 are folded multiple times as shown in Figure 5(a) and inserted horizontally through the oblong holes 39 mentioned above, and then vertically on the floors above that, and horizontally on the floors above that.

[0047] And, pack the blocks on the higher floors (for example, the 7th floor) with insulation material. And, it is more preferable to thickly cover the area around and the top of the heat storage chamber with insulation material to enhance the insulation effect.

[0048] The small semicircular window shown on the left side of Figure 5(c) allows one to see the heat transfer tube inserted at the bottom.

[0049] 5(c), reference numeral 25 denotes a heat storage material wall portion, 26 denotes a heat storage material beam portion, and 27 denotes a heat storage material partition wall portion. The heat storage material partition wall portion 27 is a wall penetrating a heat medium A pipe 28 and a heat medium B pipe 29.

[0050] FIG. 6 shows the state of the deepest heat storage chamber 3 from the power plant floor (within the ocean crust) 10.

[0051] In Figure 6, a heat transfer pipe 20 inside a center shaft excavated below the working floor surface where the deepest heat storage chamber (lowest heat storage chamber) 3 is installed from the power plant floor (inside the ocean crust) 10 extends to near the deep crustal heat area, and deep crustal heat is lifted up to the power plant floor (inside the ocean crust) 10 via that heat storage chamber and the heat storage chamber above it.

[0052] In FIG. 6, the liquid heat transfer medium 2 in the cooling tower 18 is changed to gas (steam) 17, showing the case where the heat transfer medium is used as a gas rather than a liquid. The heat transfer medium 2, which was liquid due to the high temperature, suddenly becomes gas (steam) 17, and the specific gravity decreases, so that the pressure inside the heat transfer pipe can be kept small even if the heat transfer pipe is set long, and the bursting of the heat transfer pipe 20 can be avoided. The work floor surface on the lowest level is exposed to high heat and the workers Since it is considered that this operation would be difficult, there is an advantage to adopting this method of separating the lowest working surface from the deep crustal heat zone (using a longer heat transfer pipe).

[0053] The cross-sectional configuration of the heat transfer pipe extending from the power plant floor (inside the ocean crust) 10 to near the deep crustal zone is as shown in Figure 7(a), with multiple heat collection pipes 21 (inexpensive general stainless steel pipes can be used without using special piping materials that can withstand high pressure) arranged circumferentially around a central heat recovery pipe 22 (the heat transfer medium moves inside the pipe due to the action of pump P) that collects heat using the heat transfer medium, and a protective pipe 23 that protects the entire system is provided on the outside.

[0054] With this three-layer structure, the heat collection pipes surround the heat recovery pipes to prevent the temperature of the heated heat transfer medium from dropping, and they act as insulators to prevent heat from being released into the surrounding crust.

[0055] The longitudinal configuration of such heat transfer pipes is such that a centralized heat collection pipe of about 200 to 500 m is attached at the bottom layer, and a multiple spiral tube is embedded inside the centralized heat collection pipe to increase the heat collection effect (Figure 7(a)).

[0056] In the bottom layer, the configuration described above in relation to Figure 6 is used (the heat transfer medium 2, which was liquid due to the high temperature, quickly turns into gas (steam) 17, and as its specific gravity decreases, the pressure inside the heat transfer pipe can be kept low even if the heat transfer pipe is set long, preventing the heat transfer pipe from bursting, etc.), but water or mercury is used as the liquid heat transfer medium.

[0057] Here, Fig. 7(b) shows the flow of the heat medium between adjacent floors in the depth direction. The high-temperature heat medium α rising from the bottom in the depth direction and the lower-temperature heat medium β descending from the top exchange heat inside the same heat medium tube, which can contribute to the efficiency of power generation. In other words, the heat medium α and the heat medium β exchange heat inside the heat storage chamber and outside the heat storage chamber. Fig. 7(b) shows that heat is exchanged between the heat recovery pipe 22 constituting the heat medium pipe and the heat collection pipe 21 around it outside the heat storage chamber.

[0058] (Worker rooms and work equipment rooms installed on each work floor at different depths) In addition to the heat storage chamber, at least one of a worker's room and a work equipment room is installed in each space of the work floor surface with different depths so that maintenance work can be carried out safely during construction and after completion. Figure 8 shows a case where a worker's room and a work equipment room are installed, the worker's room is equipped with air conditioning equipment, and the work equipment room is equipped with cooling equipment.

[0059] For cooling or air conditioning, liquid air (a liquid obtained by lowering the temperature of air) that can be produced in-house using electricity is sent to an evaporator and mixed with gaseous air. The liquid air evaporates, removing the heat of evaporation and lowering the temperature of the gaseous air.

[0060] Using this principle, the system shown in Figure 8 uses artificial liquid air instead of liquid air. That is, an oxygen cylinder 44 and a nitrogen tank 45 are installed, and oxygen and nitrogen are mixed in the ratio of 79% and 21%, respectively, to create the artificial air. The liquid oxygen cylinder 44 is connected to a vaporizer mixer 46 via a liquid oxygen supply valve, and the liquid nitrogen tank 45 is connected to the vaporizer mixer 46 via a liquid nitrogen supply valve. The vaporizer mixer 46 can take in room temperature air (gaseous air) through an outside air intake adjustment valve or the like. The liquid turns into gas and removes the heat of evaporation, causing the temperature to drop, and low-temperature air (cooled air) 47 is supplied from the vaporizer mixer 46.

[0061] In Fig. 8, a rest room 50 is provided as a worker's room where workers can take a rest, cooled by low-temperature air 47 and further cooled or heated by a heat pipe system 51. Also provided is a work equipment room where an excavator 52, an AI robot and underground suit 48, air bearings 49 as a transport device, etc. are stored in a cooled state.

[0062] As for underground clothing48, heat-resistant clothing (fire-resistant clothing) that can withstand radiant heat of up to 1000 degrees (manufactured by JUTEC) or fire-resistant clothing worn by firefighters with a heat resistance of 500 to 600 degrees Celsius can be used.

[0063] Furthermore, when working for a little longer, a special work suit with a three-layer structure is used, with liquefied air injected into the center layer, and the vaporized air enters the inner layer and then moves to the outer layer. This allows the worker to work safely without exposing the human body to the hot air due to the air that has entered the outer layer.

[0064] (Drilling of shafts and adits) In Figures 2, 9, 10, and 11, 11 is the center shaft, 12 is the satellite shaft, and 13 is the elevator shaft. In Figure 9, for convenience, the center shaft 11 and the satellite shaft 12 are drawn adjacent to each other, and the elevator shaft 13 and the satellite shaft 12 are drawn adjacent to each other, but in reality the center shaft 11 and the satellite shaft 12 are spaced apart (Figure 11), and the elevator shaft 13 and the satellite shaft 12 are also spaced apart (Figure 4).

[0065] As shown in Figure 9(a), satellite shafts 12 connecting adjacent upper and lower floors are provided around a center shaft 11 that runs in a straight line from the power plant floor (inside the ocean crust) 10 to near the deep crustal heat area. The lower end of satellite shaft 12-1 connecting the power plant floor (inside the ocean crust) 10 to the floor immediately below (first basement floor) and the upper end of satellite shaft 12-2 connecting the first basement floor to the floor immediately below (second basement floor) are excavated so that they overlap in the depth direction as a margin.

[0066] Reference numeral 33 shown in Figures 11(a) and (b) is a connecting shaft that connects the center shaft 11 and the satellite shaft 12. Each shaft is excavated to a depth of 200 to 500 m from the powerhouse level (inside the oceanic crust) 10 (Figure 4(b)).

[0067] The connecting shaft 33 is for enabling the heat transfer pipe to be displaced laterally from the center shaft 11 to the satellite shaft 12 when the heat transfer pipe is drawn from the power plant floor (inside the ocean crust) 10 into the heat storage room. As shown in Fig. 11(b) in the depth direction, the intermediate part is 6500 mm wide (larger than the diameter 6000 mm of the large flange 32 in Fig. 10(c)) and the uppermost and lowermost sides are horizontal shafts each 8500 mm wide when viewed from the arrow AA.

[0068] The reason why the width of the horizontal shaft is 8,500 mm at the top is because it is necessary to move the shaft (shaft) drilling equipment Y1 (Fig. 2) from the center shaft 11 to the satellite shaft 12. Also, the reason why the width of the horizontal shaft is 8,500 mm at the bottom is because it is necessary to move the shaft (shaft) drilling equipment Y1 (Fig. 2) from the satellite shaft 12 to the center shaft 11.

[0069] Regarding the connecting shaft 33, the top, customs clearance section and bottom can all be unified to a width of 8,500 mm.

[0070] In FIG. 2, Y1 is a shaft (vertical shaft) excavation device, Y2 is a horizontal shaft excavation device, and Y3 is a soil and sand recovery device, which includes an earth removal transport vehicle 15 that transports earth removal and the like on a work floor surface 16 to an elevator gauge 14 installed inside the elevator shaft as shown in FIG. 9(b).

[0071] Although the location of the elevator shaft 13 is shown on the opposite side of the satellite shafts 12 from the center shaft 11, this is not limited thereto, and it may be arranged around the center shaft together with the location of the satellite shafts 12.

[0072] The satellite shaft 12 is important as an open space for drawing in the long heat transfer pipes assembled on the power plant floor (inside the ocean crust) 10 through the connecting shaft 33 into the heat storage chamber 3 .

[0073] Items brought into the heat storage chamber 3 are mainly transported by elevator installed in the elevator shaft 13, but long heat transfer pipes are drawn into the heat storage chamber 3 through the center shaft 11, the connecting shaft 33, and the satellite shaft 12.

[0074] After the heat transfer pipes have been pulled into the heat storage chamber 3, except for the section below the lowest floor (Figure 7(a)), they are not located in the center shaft 11 as shown in Figure 4(a), but in the satellite shaft 12.

[0075] The central shaft 11 is important not only for lowering the heat transfer pipes from the power plant floor to each floor where the heat storage chambers are installed, but also for raising the deep crustal heat to the lowest floor through the heat transfer pipes, and for maintaining the satellite shafts 12 and heat storage chambers 3 from the lowest floor upwards. It is particularly indispensable for carrying in and out large equipment such as long piping, pumps, absorption chillers (for producing liquid air), and large fans. It also provides space for installing a wind tunnel to send fresh air to the lower floors.

[0076] (Drilling method) The excavation method in this embodiment will be described below. First, a tunnel T is inclined downward at a predetermined angle from the land side to connect to the power station floor (inside the ocean crust) (first excavation step). Next, a satellite shaft is excavated together with the center shaft from the power station floor (inside the ocean crust) 10 to a predetermined depth, a connecting shaft connecting the satellite shaft and the center shaft, and an elevator shaft are excavated around the center shaft (second excavation step shown in FIG. 2(a)).

[0077] Then, using a drilling device that has been brought in from one of these shafts, or that has been brought in and assembled, a first cross shaft that intersects with the center shaft formed in the second drilling step is excavated (third drilling step).

[0078] Then, the excavated soil in the third excavation step is discharged through the elevator shaft to the power plant floor (inside the ocean crust) 10, and a first work floor surface 16a is formed in the first cross shaft, which has space to install at least one of an operator's room and a work equipment room, as well as a heat storage chamber (a heat medium pipe is placed in the center shaft and used to transmit deep crustal heat of 250°C to 500°C via a heat medium moved by a pump to the power plant floor (inside the ocean crust) 10, and is pulled into the satellite shaft via the connecting shaft for relaying) (fourth excavation step shown in Figure 2(b)).

[0079] Then, the working floor surface of the power plant floor (inside the ocean crust) 10 is replaced with the first working floor surface, and the first to third steps are performed sequentially until the deep crustal heat zone is approached, without shifting the position of the center shaft, to form a second working floor surface 16b in the second cross shaft (Figures 2(c) and (d)), and the center shaft is excavated from the working floor surface farthest from the power plant floor (inside the ocean crust) 10 to a position approaching the deep crustal heat zone (the fifth excavation step shown in Figure 1).

[0080] Here, the size of the heat storage chamber 3 formed on each work floor surface is 2m in each of the vertical, horizontal and height directions as shown in Fig. 5(a). Also, the size of the worker room and the work equipment room formed on each work floor surface is 10m in length, width and height, respectively.

[0081] In this way, the size of the spaces X1 and X2 shown in FIG. 2 on each work floor surface is at least 30 m in length and width and 20 m in height.

[0082] In the second step, drilling the tunnel is done using a drilling device to make a hole in the hard rock, then dynamite is inserted and exploded, and the crushed rock is removed using a shovel loader. A shield machine can also be used to make larger spaces.

[0083] It is also possible to use the cryogenic fracturing drill head described in JP 2022-542910 A. That is, a cryogenic fluid such as cold water can be injected into a hot rock body to form a crack, and then the rotational motion or striking force of the drill head can be used to break the cracked rock body.

[0084] (Elevator installed in elevator shaft) Figure 17 shows the elevator installed in the elevator shaft 13. In Figure 17(a), a chain or wire is used as a moving body corresponding to the up and down movement of the elevator cage 14, and the hoist pays out the chain or wire when descending and winds it up when ascending. The hoist is provided with Stirling engines shown in Figure 17(b) for descending and ascending, and wireless communication control operates one Stirling engine for descending and one for ascending, enabling descent and ascent.

[0085] A Stirling engine is an engine that applies heat (high temperature T1 and low temperature T2) from the outside of a sealed cylinder and uses the expansion and contraction of air (pressure change) to move the piston. To operate a Stirling engine, each Stirling engine needs two pistons with a 90 degree phase difference and two spaces with a temperature difference.

[0086] For heat (high temperature T1 and low temperature T2), geothermal heat from deep crustal heat regions can be used. For example, heat medium α (Figure 7(b)) can be used as high temperature T1, and heat medium β, heat medium β cooled by vaporization, vaporized liquid nitrogen (Figure 8), dry ice, etc. can be used as low temperature T2.

[0087] (Assembling the heat transfer pipes and pulling them in by moving them sideways to each floor) First, as shown in FIG. 10(a), a center shaft is installed on the power station floor (within the ocean crust) 10. A tower is constructed on top of 11, and the heat transfer pipes for each floor, including the first basement floor, are assembled by welding the basic pipes. The heat transfer pipe for the first basement floor is lowered from the center shaft 11 and moved laterally to the first satellite shaft 12-1 (Figure 9(a)) and pulled into the heat storage chamber for the first basement floor which is formed on the work floor surface for the first basement floor.

[0088] Similarly, the heat transfer pipe for the second basement floor is lowered from the center shaft 11 and moved laterally to the second satellite shaft 12-2 (Figure 9(a)) and pulled into the heat storage chamber for the first basement floor which is formed on the work floor surface for the second basement floor.

[0089] As for the heat transfer pipe for the lowest layer, it is lowered from the center shaft 11 and moved laterally to the n-th satellite shaft 12-n, and then drawn into the heat storage chamber for the lowest layer formed on the work floor surface for the lowest layer.

[0090] A piping unit 100 (Figure 4(a)) is provided on each work floor surface, and the piping unit 100 connects the heat transfer pipe from the lower floor to the heat transfer pipe to the upper floor and the heat storage chamber. If the heat storage chamber is likened to a large hot water pool, the piping unit can be likened to a small hot water pool. Deep crustal heat flows from the bottom to the top, but in the intermediate space between the heat transfer pipe from the lower floor and the heat transfer pipe to the upper floor, it is pooled in the piping unit as a small hot water pool, and in the heat storage chamber as a large hot water pool.

[0091] In the piping unit and heat storage chamber in this intermediate space, the heat transfer pipes are designed as shown in Fig. 7(b) (the heat recovery pipes 22 and the heat collection pipes 21 around them) to prevent the deep crustal heat from cooling. In other words, the high-temperature heat transfer medium α rising from the bottom in the depth direction and the lower-temperature heat transfer medium β falling from the top exchange heat inside the same heat transfer pipe.

[0092] Here, the significance of providing a heat storage chamber is that the heat transfer from the internal environment of the heat transfer pipe is not sufficient. That is, the significance of providing a heat storage chamber is to transfer heat from the external environment of the heat transfer pipe (to make the surrounding environment of the heat transfer pipe warm and to receive heat from adjacent different heat transfer pipes).

[0093] The diameter of the center shaft 11 and the satellite shaft 12 is 8000 mm, the maximum width (upper and lower parts) of the connecting shaft 33 is 8500 mm, and the minimum width (center part) is 6500 mm (Fig. 11(b)). As shown in Figs. 10(b) and (c), the heat transfer pipes 20 (250 to 500 m long, about 40 pieces) are bundled with a large flange 32. The outer diameter of the large flange 32 is 6 m (6000 mm) as shown in Fig. 10(c), and the weight of the heat transfer pipes 20 is very large. For this reason, the heat transfer pipes 20 are placed on a disk supported by about 10 rotating chains 63 and gradually lowered via a rotating pulley 62. When the target floor is reached, the heat transfer pipes 20 are moved laterally from the center shaft 11 to the satellite shaft 12 and connected to the heat storage chamber 3.

[0094] (Excavation of tunnel access for utilizing deep crustal heat for thermal power generation) Furthermore, in this embodiment, in order to form a huge power station using many thermoelectric power generation element units that generate electricity by using deep crustal heat as the power generation section, many tunnel access shafts will be excavated. If existing tunnels can be used, they will be used.

[0095] More specifically, with regard to the tunnel 42 shown in FIG. 12, as shown in FIG. 13(a), the method includes the steps of forming a plurality of tunnels, each having a diameter of 8 m, at a predetermined interval (e.g., 16 m) from each other in a first direction (X direction), and forming a second tunnel adit at a predetermined interval (e.g., 16 m) from the first tunnel adit in the depth direction (Z direction), and at a predetermined interval (e.g., 16 m) from each other in a second direction (Y direction) intersecting the first direction.

[0096] In this way, the first group of tunnels and the second group of tunnels are arranged so as to intersect (orthogonally) with each other (FIG. 13(a)).

[0097] The siding 53 shown in Figures 12 and 13(b) refers to a lead-in track to each tunnel adit or a track for shunting that is provided separately from the track (rail) laid inside each tunnel adit so that moving vehicles can move inside the tunnel adit. The lower floor surface of Figure 13(b) shows the state after being drawn into the tunnel adit, and the upper floor surface of Figure 13(b) shows the state before a new thermoelectric element unit 4 is drawn into the tunnel adit by a maintenance and replacement vehicle.

[0098] The overall layout space of each tunnel 42 is such that about 10 units, each 3500 m in the X and Y directions and 30 m in the Z direction, are connected to each other within the XY plane.

[0099] In each tunnel 42, a plurality of thermoelectric power generation element units 4 spaced 16 m apart from one another are carried in and installed by a mobile vehicle 72 such as a trolley shown in Fig. 12 in a connected state. Then, the thermoelectric power generation elements in different tunnels 42 are connected to one another by sidings 53.

[0100] (Thermoelectric power generation element unit) Generally, thermoelectric generating elements (temperature difference generating elements) are known from the following documents.

[0101] · January 13, 2021 issue Journal of physics D; Applied physics pp.115503 Mixed-Phase effect of the high Seebeck coefficient and low electrical resistivity in the Ag2S 2) August 21, 2019, Nikkei Shimbun NEDO, Aisin Seiki, and Ibaraki University announced that they have succeeded in developing a technology that uses only common materials to generate electricity using slight temperature differences such as body heat. Made of iron, aluminum, and silicon, it does not contain any rare or toxic elements like conventional materials, and material costs can be reduced to one-fifth or less.

[0102] It is expected that further research and development of such thermoelectric power generation elements will be carried out in the future. In this embodiment, the thermoelectric power generation elements using the Seebeck effect are unitized as thermoelectric power generation element units (element units), and the earth's heat transmitted to the power plant floor (inside the ocean crust) 10 by the heat medium pipe is circulated to the high temperature side, while cold water is circulated to the low temperature side, and electricity is generated by the temperature difference between the two. A large number of these element units are used to configure a huge power plant with a capacity of several million kW.

[0103] Figure 14(a) shows an image of an element board equipped with multiple thermoelectric generation elements for temperature difference power generation and how to make it. Alumel wire with a wire diameter of 1 mm is used with a vertical wire density of 23,322 wires / 75,000 mm 2 The ceramic element is wrapped around a U-shaped SUS plate and both ends are fixed with ceramic material. Then, multiple element plates like this are arranged.

[0104] In FIG. 14(b), the element boards 37 are arranged one-dimensionally in the longitudinal direction, and multiple element boards 37 are arranged in a direction intersecting the longitudinal direction, with heat transfer medium flow paths 35 and cold water flow paths 36 arranged alternately in parallel, sandwiching each thermoelectric power generation element, in the direction intersecting the longitudinal direction.

[0105] In Fig. 15(a), the element board 37 is arranged two-dimensionally, and the heat medium flow path and the cold water flow path are arranged perpendicular to each other. In Fig. 15(a) and (b), 38 indicates the flow of high-temperature heat medium α, 39 indicates the flow of cold water, 40 indicates drainage, and 41 indicates the return of the cooled heat medium β to the heat storage chamber.

[0106] Figure 16(a) shows the experimental method and circuit diagram for measuring the amount of power generated by a thermoelectric generating element, and Figure 16(b) shows the experimental results. In the figure, 54 is a kettle, 55 is an ice pack, 56 is an Alumel wire, 57 is a copper plate, 58 is a Bakelite plate, 59 is pine wood, 60 is an ammeter, and 61 is a voltmeter. From the experimental results, it was demonstrated that, using 100°C on the high temperature side and 0°C on the low temperature side, the thermoelectric generating element output 0.2mW of power due to the Seebeck effect.

[0107] By providing a large number of such thermoelectric generating elements (for example, 100 billion elements when the temperature difference is 100° C.), a large power plant such as the one shown in FIG. 12 and FIG. 13 can output a large amount of power (for example, 2 million kW).

[0108] Second embodiment In the first embodiment described above, one heat storage chamber 3 is provided on each floor, but in this embodiment, multiple (typically two) are provided. As a result, on the premise of using the same heat storage chamber (same number of heat transfer pipes n) as in the first embodiment, the total number of heat transfer pipes (particularly heat recovery pipes) becomes multiple times (n × number of heat storage chambers on each floor) compared to the first embodiment, and the power generation capacity of the power plant can be increased multiple times.

[0109] Fig. 18 showing this embodiment corresponds to Fig. 9(a) in the first embodiment. Satellite shafts 12-1-a and 12-1-b are formed in line symmetry with respect to the center shaft 11, and the elevator shaft 13 is also formed in line symmetry with respect to the center shaft 11. Satellite shafts 12-2-a and 12-2-b are also formed in line symmetry with respect to the center shaft 11, and are arranged in the same manner as satellite shafts 12-1-a and 12-1-b.

[0110] As for the heat storage chambers 3, as in FIG. 4, they are provided on the opposite side of the satellite shafts from the center shaft 11, and in this embodiment, one is provided corresponding to each satellite shaft (total of two) on the same floor (for example, the same floor corresponding to satellite shafts 12-2-a and 12-2-b).

[0111] In this embodiment, assuming that the same heat storage chamber as in the first embodiment is used, the total number of heat transfer pipes moved laterally into the satellite shaft needs to be multiple times (e.g., twice) larger than in the first embodiment, but the third embodiment described below can essentially meet this requirement.

[0112] (Third embodiment) In this embodiment, the heat transfer pipes (having a heat recovery pipe in the center of the cross section, multiple heat collection pipes in the peripheral part of the cross section, and a protective pipe in the outer part of the cross section) that are moved laterally to the satellite shaft are unitized as a heat transfer pipe unit, thereby increasing the number of heat transfer pipes in the satellite shaft and keeping the width of the connecting shaft 33 for lateral movement small.

[0113] In the first embodiment, the number of heat transfer pipes moved laterally into the satellite shaft was 40, but in this embodiment, the number can be almost doubled to 90. Note that in the above-mentioned embodiment, the diameter of the satellite shaft was 8000φ (8 m), the same as the diameter of the center shaft, but in this embodiment, the diameter of the satellite shaft is assumed to be 9000φ (9 m).

[0114] Regarding the heat transfer pipes arranged inside the satellite shafts, in the first embodiment, as shown in Figures 10(b) and (c), multiple heat transfer pipes restricted by large flanges 32 are moved laterally as a unit from the center shaft 11 to the satellite shaft 12, but in this embodiment, multiple heat transfer pipes restricted by small flanges are moved laterally in chronological order to the satellite shaft 12 one after another.

[0115] In this embodiment, a heat transfer pipe a having a diameter of 415 mm configured as shown in Fig. 19(a) (having a heat recovery pipe 22 having a diameter of 216.3 mm in the cross-sectional center, a plurality of heat collection pipes 21 having a diameter of 89.1 mm in the cross-sectional peripheral portion, and a protective pipe 23 on the outer cross-sectional portion) is used as a1 to a8 and unitized as a heat transfer pipe unit A having a diameter of 2000 mm as shown in Fig. 19(b). Unitization allows mass production by an automatic welding method using a welding robot, resulting in significant cost reduction.

[0116] In this embodiment, nine heat medium pipe units A (A1 to A9) are arranged in the satellite shaft 12 as a heat medium pipe group with a diameter of 9000 mm shown in FIG. 19(c). More specifically, instead of the large flange 32 (FIGS. 10(b) and (c)) in the first embodiment, the heat medium pipe units A1 to A10 are arranged in chronological order in the satellite shaft 12 as shown in FIG. 19(c) while being restricted by a small flange 132 (having openings corresponding to the heat medium pipe units a1 to a8) with a plate thickness of 10 mm and a diameter of 2000 mm shown in FIG. 20. That is, the heat medium pipe unit A1 is first arranged in the position shown in FIG. 19(C), then the heat medium pipe unit A2 is arranged in the position shown in FIG. 19(C), similarly the heat medium pipe units A3 to A8 are arranged in the positions shown in FIG. 19(C), and finally the heat medium pipe unit A9 is arranged in the position shown in FIG. 19(C).

[0117] With this configuration, in this embodiment, as shown in Fig. 22, the width of the connecting shaft 33, which was 6500 mm (Fig. 11) in the first embodiment, can be reduced to about 3000 mm (larger than the diameter of the small flange 132, 2000 mm). In this embodiment, assuming that the diameter of the satellite shaft is 9000φ (9 m), the area of ​​the upper and lower shaft excavator length + 5000 mm in Fig. 22 becomes large at 9500 mm, but the vertical length of the area with a width of 3000 mm is longer than the area with a width of 9500 mm, thereby reducing the cost of the excavation process.

[0118] Here, in FIG. 21, the piping unit in this embodiment is shown, and FIGS. 21(a), (b), and (c) are a plan view, a vertical cross-sectional view, and a perspective view of the piping unit in this embodiment, respectively.

[0119] Fig. 21(a) is a plan view of the piping units arranged in the satellite shaft, and corresponds to the heat transfer pipe group (heat transfer pipe units A1 to A9) in Fig. 19(c). A collecting chamber is provided in the center, and piping is connected radially to each heat transfer pipe unit by flanges indicated by thick black lines.

[0120] In this piping unit, the upper chamber and the lower chamber are joined in a structure in which they are arranged symmetrically with respect to the joining surface, as shown in Figure 21(b). The upper chamber and the lower chamber each have a peripheral bank portion formed in a ring shape around the periphery, a central bank portion whose center is the highest, and a recessed portion between them.

[0121] Heat medium pipe units A1 to A9 are connected to the peripheral banks of the upper chamber, and the heat recovery pipe 22 reaches the lower chamber from the upper chamber across the joint surface, while the heat collection pipe 21 remains in the upper chamber.

[0122] The inside of the collective chamber and the inside of the heat storage chamber of the floor are connected by piping so as to go under the peripheral bank of the lower chamber. Specifically, the position P of the collective chamber part in the lower chamber and the heat storage chamber of the floor are connected by piping so as to go under the peripheral bank of the lower chamber.

[0123] In addition, the position Q of the collective chamber in the upper chamber and the heat storage chamber of the corresponding floor are connected by piping as follows. That is, position Q and position R of the recess are connected as part of the piping connection, and the piping is bent straight down from position R and descends, then bent again and connected so as to go under the peripheral bank of the lower chamber. This makes it possible to avoid physical interference with the heat transfer pipe unit.

[0124] Heat medium α that has passed through the heat storage chamber on the lower floor and the heat medium pipe from the lower floor fills the inside of the piping leading to the heat storage chamber on that floor and the inside of the bank around the lower chamber. Also, heat medium β that has passed through the heat storage chamber on the upper floor and the heat medium pipe from the upper floor fills the inside of the piping leading to the heat storage chamber on that floor and the inside of the bank around the upper chamber.

[0125] According to the structure of this embodiment, the high-temperature heat transfer medium α rising from the bottom in the depth direction and the lower-temperature heat transfer medium β descending from the top exchange heat not only inside the heat storage chamber on that floor but also in the collection chamber, thereby contributing to the efficiency of power generation.

[0126] (Fourth embodiment) In this embodiment, the power station on the power station floor in the above-mentioned embodiment is a dome type covered with a dome 70 shown in Fig. 23(a), and the power station floor is installed 0.1 to 0.2 km from the seabed, and the other configurations are the same as those of the first to third embodiments. It is more preferable that the operator room described in Fig. 8 is also dome type.

[0127] It is necessary to excavate hard bedrock such as basalt and peridotite into a dome shape, but by developing and using a robotic system that mounts a dedicated excavator on a huge lifter and can excavate unmanned according to instructions from a computer, excavation can be carried out cleanly and quickly, and costs can be significantly reduced.

[0128] The effects of the dome 70 are as follows. As shown in Figure 23(b), by pumping an ample amount of fresh mountain air into the dome and maintaining a positive pressure inside, air leaks steadily through the gaps in the canvas that forms the dome, keeping the air inside always fresh. By discharging the leaked air to the outside, the air between the excavated dome and the canvas that has been inflated by the internal air is discharged from the dome building. As a result, the radiant heat received from the outer wall of the dome is discharged from inside the dome by the moving air, lowering the temperature of the air between the outer wall of the dome and the canvas of the dome.

[0129] Furthermore, by making the outer surface of the dome canvas highly reflective, the radiant heat emitted by the outer wall is repelled, significantly reducing the amount of heat transferred to the inside of the dome.

[0130] The method of blocking the radiant heat coming from the ground inside the dome is to first lay a thick layer (2-5m) of large crushed stone resulting from large excavations on the ground inside the dome, cover that with two layers of nonwoven fabric, and then lay a thick layer (2-5m) of medium-sized crushed stone on top of that. Then, cover that with two layers of nonwoven fabric, and lay small crushed stone on top of that. Then, lay a thick layer (10-15m) of topsoil (transported by return dump trucks) obtained from a landfill site for soil removal on the mountain. This creates soil that contains a lot of air, which provides great insulation.

[0131] The ground of such a dome is covered with a thick layer of excavated soil, and the surface is covered with a thick layer of topsoil from the mountain. Trees can be planted here, and artificial solar lighting can be installed to encourage trees and grass to grow, or a biotope can be created to create an environment close to nature. This creates shade, and the trees and biotope have the potential to provide a cooling effect on the air.

[0132] To insulate the vertical circumference of the dome, a thick layer (2 to 5 m) of insulation material, mainly rock wool, will be attached to the walls, and the steel-framed walls will be covered with highly insulating building materials such as ALC panels.

[0133] Furthermore, the operator's room explained in Fig. 8 can also be made into a small dome structure to reduce the heat load. The dome-shaped excavation equipment can also be operated unmanned by a robot.

[0134] In addition, the power plant could be equipped with hot spring facilities that use a heat transfer medium, and lodging facilities could be set up to serve as an inn where visitors can stay.

[0135] According to the embodiment of the present invention described above, unlike power generation that uses magma steam, which can become unstable due to magma movement, ultra-long-term stable power generation and even large-scale power generation can be expected.

[0136] By using the drilling method according to this embodiment, fuel-free power generation that does not use fossil fuels such as coal or natural gas becomes possible, eliminating the need to import fuel (self-supplied emergy source). Since the demand in the metropolitan area can be met from power plants in the suburbs, the transmission distance becomes shorter, reducing transmission losses. In addition, most of the equipment has no moving parts, has a long life, and reduces maintenance costs.

[0137] Furthermore, it can be used in most places around the world, except in volcanic areas and places prone to tectonic activity. It is possible to generate electricity in the desert, draw water from large rivers and lakes, green the desert, and build oasis cities with large-scale power generation. And by turning the desert into arable land, it is possible to increase food production to alleviate the world's food shortage.

[0138] (Hydrogen production) Although the present invention has been described in the first to fourth embodiments with respect to power generation using deep geothermal heat, the present invention is not limited to obtaining electricity through power generation, but also includes generating (producing) hydrogen (green hydrogen) using power generation. Figure 26 shows that hydrogen (green hydrogen) is generated (produced) by adding water and power generation using deep geothermal heat to an electrolytic cell.

[0139] Hydrogen has a wide range of uses, including fuel cells, engines for ships, heat utilization in industrial furnaces, reduction ironmaking (as an alternative to coke), and chemical synthesis, and can make a significant contribution to reducing CO2 emissions.

[0140] And what is important is that this invention makes it possible to generate hydrogen at low cost by using deep crustal heat (no fuel costs) without relying on coal or oil. And when generating electricity using a temperature difference power generation method, no CO2 is emitted at all, which is the most favorable form for the global environment.

[0141] (Modification) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of the gist of the present invention.

[0142] In the above embodiment, the center shaft is described as being provided penetrating from the power plant floor (inside the ocean crust) 10 to a position approaching the deep crustal heat area, but the center shaft may be provided so as to suitably follow a continuous trajectory from a position approaching the deep crustal heat area to the power plant floor (inside the ocean crust) 10 via a plurality of heat storage chambers. For example, the center shaft 11 may be provided parallel to and offset between different work floor surfaces by increasing the number of heat storage chambers and shortening the heat storage pipes connecting adjacent heat storage chambers in the depth direction, thereby providing a height for the work floor surface and erecting the heat storage pipes on the work floor surface.

[0143] Moreover, the above-mentioned shafts may be excavated simultaneously from the power station level (within the ocean crust) 10, or may be excavated non-simultaneously.

[0144] In addition, the satellite shaft 12 is not limited to being formed between the center shaft 11 and the elevator shaft 13 (Figure 9 (a)), but the center shaft 11 may be formed between the satellite shaft 12 and the elevator shaft 13.

[0145] In the above embodiment, the crustal heat from non-volcanic deep crustal heat areas is used to generate electricity by a temperature difference power generation system, but the crustal heat from non-volcanic deep crustal heat areas may be used to generate electricity by a known turbine system as shown in Fig. 25. The crustal heat from non-volcanic deep crustal heat areas may be shared between the temperature difference power generation system and the turbine system, and for example, electricity may be generated mainly by the temperature difference power generation system while the remaining electricity may be generated by the turbine system as a secondary power generation system.

[0146] In addition, in the above-described embodiment, the tunnel heading toward the power plant from the land side has an area that slopes diagonally downward from the land side, but it may also be a tunnel that connects a vertical tunnel up to the power plant's installation surface with a horizontal tunnel within the power plant's installation surface (using two sides that form a right angle instead of the hypotenuse of a right triangle). [Explanation of symbols]

[0147] 1··Deep crust high temperature zone, 3··Heat storage chamber, 4··Thermoelectric power generation element unit, 9··Power plant (inside the ocean crust), 10··Power plant floor (inside the ocean crust), 11··Center shaft, 12··Satellite shaft, 13...Elevator shaft, 16...Work floor, 20··Heat transfer pipe, 28··Heat transfer A piping, 29··Heat transfer B piping, 33··Connecting shaft, 50··Resting room, P··Pump, T··Tunnel

Claims

1. A power plant located within the oceanic crust; A heat transfer pipe for transferring geothermal heat from a non-volcanic deep crustal heat region to the power plant via a heat transfer medium; A heat storage chamber provided on each floor at a different depth from the power plant; A piping unit is provided on each floor and connected to the heat transfer pipe and the heat storage chamber; having A space in which a first heat medium as the heat medium rising from a lower floor exists, and a space in which a second heat medium which has reached the power plant and descended from an upper floor and has a lower temperature than the first heat medium exists are separately arranged adjacent to each other in the heat medium pipe and the piping unit, respectively, thereby suppressing heat loss due to the transfer of heat; A power generation system in which the geothermal heat passing through the plurality of heat storage chambers is used to generate power in the power plant by a temperature difference power generation method or a turbine method, The heat transfer pipe has a space in which the first heat transfer medium is present and a space in which the second heat transfer medium is present, the space being separated at a central portion and a peripheral portion in a cross section of the heat transfer pipe; A power generation system, wherein the piping unit has a space in which the first heat medium is present and a space in which the second heat medium is present, the space being vertically separated from one another.

2. 2. The power generation system according to claim 1, wherein the power plant is provided in the ocean crust in a coastal area and connected to the land side through a tunnel.

3. 2. The power generation system according to claim 1, wherein the heat transfer pipe includes a heat recovery pipe in a cross-sectional center portion as a space in which the first heat transfer medium is present, a plurality of heat collection pipes in a cross-sectional peripheral portion as a space in which the second heat transfer medium is present, and a protective pipe in an outer cross-sectional portion, and the plurality of heat transfer pipes are unitized as a heat transfer pipe unit.

4. The power generation system according to any one of claims 1 to 3, wherein a plurality of the heat storage chambers are provided on the same floor at the same depth from the power plant.

5. A power plant located within the oceanic crust; A heat transfer pipe for transferring geothermal heat from a non-volcanic deep crustal heat region to the power plant via a heat transfer medium; A heat storage chamber provided on each floor at a different depth from the power plant; A piping unit is provided on each floor and connected to the heat transfer pipe and the heat storage chamber; A first step of installing A space in which a first heat medium as the heat medium rising from a lower floor exists, and a space in which a second heat medium which has reached the power plant and descended from an upper floor and has a lower temperature than the first heat medium exists are separately arranged adjacent to each other in the heat medium pipe and the piping unit, respectively, thereby suppressing heat loss due to the transfer of heat; A second step of generating electricity from the geothermal heat that has passed through the plurality of heat storage chambers in the power plant by a temperature difference power generation method or a turbine method; A method for generating electricity comprising the steps of: The heat transfer pipe has a space in which the first heat transfer medium is present and a space in which the second heat transfer medium is present, the space being separated at a central portion and a peripheral portion in a cross section of the heat transfer pipe; The power generating method, wherein the piping unit has a space in which the first heat medium is present and a space in which the second heat medium is present, the space being vertically separated from each other.

6. A method for producing hydrogen, comprising the steps of: producing hydrogen by using power generation according to the method for generating electricity according to claim 5 ;

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