Energy storage device and energy storage system

Abstract

This energy storage device comprises: a first compressed gas cylinder having a first cylinder, a gas enclosed in a first space partitioned inside the first cylinder, and a first compressed gas cylinder temperature regulator for regulating a temperature; a second compressed gas cylinder having a second cylinder, a liquid enclosed in a second space partitioned inside the second cylinder, and a second compressed gas cylinder temperature regulator for regulating a temperature; a third compressed gas cylinder having a third cylinder and a third compressed gas cylinder temperature regulator for regulating a temperature; piping; and a control unit.

Description

Energy Storage Device and Energy Storage System

[0001] The present invention relates to an energy storage device for storing energy and an energy storage system.

[0002] In recent years, energy storage technologies have been attracting attention in order to stably utilize renewable energies such as wind power generation and solar power generation.

[0003] Examples of energy storage technologies include storage batteries, pumped storage, heat storage, production of hydrogen and ammonia, and compressed air energy storage.

[0004] Compressed air energy storage is an energy storage technology that stores air compressed by surplus energy, for example, using a compressed air energy storage system as described in Patent Document 1, in the seabed or the like, and uses the stored air as needed.

[0005] Japanese Patent Application Laid-Open No. 02-071055

[0006] However, a compressed air energy storage system as described in Patent Document 1 tends to have a large facility scale and may incur high construction costs.

[0007] Further, a compressed air energy storage system as described in Patent Document 1 uses a turbine. When storing energy, air is compressed in a state close to adiabatic, and when using the stored energy, air is expanded in a state close to adiabatic. Here, since the adiabatic change is PV γ =constant, and the isothermal change is PV = constant, in the P-V graph, the slope in the case of adiabatic change becomes steeper than the slope in the case of isothermal change. Therefore, when storing energy, the pressure in adiabatic compression becomes higher than that in isothermal compression, and more energy is required. Also, when using energy, the pressure in adiabatic expansion becomes lower than that in isothermal expansion, and the energy that can be extracted becomes lower. For this reason, a compressed air energy storage system as described in Patent Document 1 may not have good energy efficiency.

[0008] Therefore, one of the objectives of the present invention is to provide a novel energy storage device.

[0009] An energy storage device according to one embodiment of the present invention comprises: a first cylinder having a first cylinder, a gas sealed in a first space partitioned inside the first cylinder, and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder, a liquid sealed in a second space partitioned inside the second cylinder, and a second cylinder temperature regulator for adjusting the temperature; a third cylinder having a third cylinder, a third cylinder temperature regulator for adjusting the temperature; a first pipe having one end leading to the first space; and the other end leading to the second... A pipe having a second pipe leading to a space, a third pipe whose one end leads to a third space partitioned inside the third cylinder, a branch section leading to the other of the first pipe, the second pipe and the third pipe, a second pipe temperature regulator for adjusting the temperature of a part of the second pipe, and a third pipe temperature regulator for adjusting the temperature of a part of the third pipe, and changing the volume of the first space, the volume of the second space and the volume of the third space, the first cylinder temperature regulator, the second cylinder temperature regulator and the third cylinder temperature regulator and the second The system includes a pipe temperature regulator and a control unit that controls the third pipe temperature regulator. When energy is stored, the control unit controls the first cylinder temperature regulator and the second cylinder temperature regulator so that the temperature of the first cylinder is higher than the temperature of the second cylinder, and the control unit reduces the volume of the first space so that the gas moves from the first space to the first pipe, the branch section and the second pipe, and the control unit controls the second pipe temperature regulator so that the temperature of the gas is the temperature of the second cylinder, and the gas moves to the second When the energy stored in the liquid is used after it has moved to the second space through the piping, the control unit controls the first cylinder temperature regulator, the second cylinder temperature regulator and the third cylinder temperature regulator so that the temperature of the first cylinder is higher than the temperatures of the second and third cylinders, and the control unit reduces the volume of the second space so that the liquid moves from the second space to the second piping, and the control unit controls the second piping temperature regulator so that the temperature of the liquid is the same as the temperature of the first cylinder.The gas emitted from the liquid moves to the first space through the second pipe, the branch section, and the first pipe; the liquid from which the gas has been emitted moves to the second pipe, the branch section, and the third pipe; the control unit controls the third pipe temperature controller so that the temperature of the liquid reaches the temperature of the second cylinder; and the liquid moves to the third space through the third pipe.

[0010] In an energy storage device according to one embodiment of the present invention, the second pipe temperature controller may include, in order from the branching section, a second-first pipe temperature controller and a second-second pipe temperature controller, and the third pipe temperature controller may include, in order from the branching section, a third-first pipe temperature controller and a third-second pipe temperature controller.

[0011] In an energy storage device according to one embodiment of the present invention, thermal energy may be exchanged between the 2-1 pipe temperature controller and the 3-1 pipe temperature controller, and thermal energy may be exchanged between the 2-2 pipe temperature controller and the 3-2 pipe temperature controller.

[0012] In an energy storage device according to one embodiment of the present invention, the gas may be carbon dioxide, and the liquid may be water.

[0013] An energy storage device according to one embodiment of the present invention comprises: a first cylinder having a first cylinder; a second cylinder having a second cylinder; a third cylinder having a third cylinder; piping having a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder, and a second pipe connecting the second space and a third space partitioned inside the third cylinder; a medium sealed in the first space and moving through the first pipe and the second pipe to the first space, the second space and the third space; and a control unit that changes the volume of the first space and the volume of the second space. The maximum volume of the third cylinder is greater than the maximum volume of the second cylinder. When storing energy, the control unit reduces the volume of the first space so that the medium sealed in the first space moves to the second space through the first pipe. The control unit reduces the volume of the second space so that the medium is pressurized. The control unit reduces the volume of the second space so that the medium moves from the second space to the third space through the second pipe. When using the stored energy, the control unit reduces the volume of the third space so that the medium moves from the third space to the second space through the second pipe and increases the volume of the second space.

[0014] An energy storage device according to one embodiment of the present invention includes: a first cylinder having a first cylinder; a second cylinder having a second cylinder; a third cylinder having a third cylinder; a fourth cylinder having a fourth cylinder; a piping having: a first piping connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder; a second piping connecting the second space and a third space partitioned inside the third cylinder; a third piping connecting the third space and a fourth space surrounded by the fourth cylinder and the fourth piston; and a fourth piping connecting the fourth space and the first space; a medium sealed in the fourth space that moves through the fourth piping, the first piping, the second piping and the third piping to the fourth space, the first space, the second space and the third space; and the first The system includes a control unit that changes the volume of the first space, the volume of the second space, the volume of the third space, and the volume of the fourth space, wherein the maximum volumes of the second and fourth cylinders are greater than the maximum volumes of the first and third cylinders, and when storing energy, the control unit reduces the volume of the fourth space so that the medium sealed in the fourth space moves to the first space through the fourth pipe, the control unit reduces the volume of the first space so that the medium is pressurized, the control unit reduces the volume of the first space so that the medium moves from the first space to the second space through the first pipe, and when using the stored energy, the control unit reduces the volume of the second space so that the medium moves from the second space to the third space through the second pipe and increases the volume of the third space.

[0015] In an energy storage device according to one embodiment of the present invention, the medium may be carbon dioxide.

[0016] An energy storage device according to one embodiment of the present invention includes: a first cylinder having a first cylinder and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder; a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder; a second pipe connecting the second space and the first space; a pipe having a first pipe temperature regulator for adjusting the temperature of a part of the first pipe and a second pipe temperature regulator for adjusting the temperature of a part of the second pipe; a medium sealed in the first space and moving to the first space and the second space through the first pipe and the second pipe; and a device that changes the volume of the first space and the volume of the second space and controls the first pipe temperature regulator and the second pipe temperature regulator. The device comprises a control unit, wherein the maximum volume of the first cylinder is greater than the maximum volume of the second cylinder, the control unit controls the second cylinder temperature controller so that the temperature of the second cylinder is higher than the temperature of the first cylinder, the control unit reduces the volume of the first space so that the medium moves from the first space to the first piping, the medium is heated in the first piping temperature controller, the medium moves through the first piping to the second space, the control unit reduces the volume of the second space so that the medium is pressurized and thermal energy is released, the control unit reduces the volume of the second space so that the medium moves from the second space to the second piping, the medium is cooled in the second piping temperature controller, and the medium moves through the second piping to the first space.

[0017] In an energy storage device according to one embodiment of the present invention, the thermal energy discharged when the medium is cooled by the second pipe temperature controller may be used when the medium is heated by the first pipe temperature controller.

[0018] An energy storage device according to one embodiment of the present invention includes: a first cylinder having a first cylinder and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder; a third cylinder having a third cylinder; a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder; a second pipe connecting the second space and a third space partitioned inside the third cylinder; a third pipe connecting the third space and the first space; a pipe having a first pipe temperature regulator for adjusting the temperature of a part of the first pipe and a third pipe temperature regulator for adjusting the temperature of a part of the third pipe; a medium sealed in the third space that moves through the third pipe, the first pipe and the second pipe to the third space, the first space and the second space; the volume of the first space, the volume of the second space and the The system includes a control unit that changes the volume of a third space and controls the first pipe temperature controller and the third pipe temperature controller, wherein the maximum volume of the third cylinder is greater than the maximum volume of the first cylinder, the control unit controls the first cylinder temperature controller so that the temperature of the first cylinder is higher than the temperature of the third cylinder, the control unit reduces the volume of the third space so that the medium moves from the third space to the third pipe, the medium is heated in the third pipe temperature controller, the medium moves through the third pipe to the first space, the control unit reduces the volume of the first space so that the medium is pressurized and thermal energy is released, the control unit reduces the volume of the first space so that the medium moves from the first space to the first pipe, the medium is cooled in the first pipe temperature controller, and the medium moves through the first pipe to the second space.

[0019] In an energy storage device according to one embodiment of the present invention, the thermal energy discharged when the medium is cooled by the first pipe temperature controller may be used when the medium is heated by the third pipe temperature controller.

[0020] An energy storage system according to one embodiment of the present invention includes an energy storage device and a generator connected to the energy storage device.

[0021] According to one embodiment of the present invention, a novel energy storage device can be provided.

[0022] This is a schematic diagram of a cylinder according to one embodiment of the present invention. This is a schematic diagram of a cylinder according to one embodiment of the present invention when the piston is moved upward. This is a schematic diagram of a cylinder according to one embodiment of the present invention when the piston is moved downward. This is a schematic diagram of a cylinder according to one embodiment of the present invention when multiple cylinders according to one embodiment of the present invention are connected in parallel. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of a cylinder according to another embodiment of the present invention. This is a schematic diagram of an energy storage device according to the first embodiment of the present invention. This is a block diagram showing the relationship between the control unit and other components in the energy storage device according to the first embodiment of the present invention. This is a schematic diagram showing the operation of the energy storage device according to the first embodiment of the present invention. This is a schematic diagram showing a modified example of the energy storage device according to the first embodiment of the present invention. This is a schematic diagram showing the operation of This is a schematic diagram showing the operation of an energy storage device according to a second embodiment of the present invention. This is a schematic diagram showing the operation of an energy storage device according to a second embodiment of the present invention. This is a schematic diagram showing the operation of an energy storage device according to a second embodiment of the present invention. This is a schematic diagram showing the operation of an energy storage device according to a second embodiment of the present invention. This is a schematic diagram showing the operation of an energy storage device according to a second embodiment of the present invention. This is a schematic diagram of a modified example 1 of the energy storage device according to a second embodiment of the present invention. This is a block diagram showing the relationship between the control unit and other components in a modified example 1 of the energy storage device according to a second embodiment of the present invention. This is a schematic diagram showing the operation of a modified example 1 of the energy storage device according to a second embodiment of the present invention.This is a schematic diagram showing the operation of a modified example 1 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram of a modified example 2 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram showing the operation of a modified example 2 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram showing the operation of a modified example 2 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram showing the operation of a modified example 2 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram showing the operation of a modified example 3 This is a schematic diagram showing the operation of a modified example 3 of the energy storage device according to the second embodiment of the present invention. This is a schematic diagram showing the operation of the energy storage device according to the third

[0023] Embodiments of the present invention will be described below with reference to the drawings. While the drawings may schematically represent the width, thickness, shape, etc., of parts in order to clarify the explanation, they are merely examples and do not limit the interpretation of the present invention. In this specification and in the drawings, elements similar to those described above in previous drawings are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

[0024] (Cylinder) The cylinder, which is the basic component of the energy storage device according to one embodiment of the present invention, will be described. Figure 1 is a schematic diagram of a cylinder 100 according to one embodiment of the present invention. As shown in Figure 1, the cylinder 100 has a cylinder 110, a piston 120, a medium 130, and a cylinder temperature regulator 140. The maximum volume per cylinder (maximum volume of space S) is set, for example, between 0.01 L and 1,000 L.

[0025] The cylinder 110 is cylindrical in shape, extending vertically, with a closed top and an open bottom. Examples of external shapes of the cylinder 110 in a cross-sectional view along the left-right direction include circular, elliptical, and triangular polygons. Examples of internal shapes of the cylinder 110 in a cross-sectional view along the left-right direction include circular, elliptical, and triangular polygons. Examples of materials for the cylinder 110 include iron, aluminum, and synthetic resin.

[0026] The piston 120 includes a head portion 121 and a rod portion 122 connected to the head portion 121. The head portion 121 has a columnar shape extending in the vertical direction. The rod portion 122 also has a columnar shape extending in the vertical direction. The shapes of the head portion 121 and the rod portion 122 in a cross-sectional view along the left-right direction include, for example, polygons such as circles, ellipses, and triangles, similar to the internal shape of the cylinder 110. Examples of materials for the head portion 121 and the rod portion 122 include iron, aluminum, and synthetic resin. The rod portion 122 can be connected directly or indirectly to a generator or the like via gears or hydraulics.

[0027] The piston 120 is inserted into the cylinder 110 from the lower opening of the cylinder 110, in the order of head portion 121 and rod portion 122. Because the internal shape of the cylinder 110 and the external shape of the head portion 121 match, the piston 120 can slide vertically inside the cylinder 110. A space S is formed surrounded by the inside of the cylinder 110 and the upper part of the head portion 121. In other words, space S is partitioned inside the cylinder 110. As the piston 120 moves upward inside the cylinder 110, the volume of space S decreases, as shown in Figure 2. With the medium 130 sealed in the enclosed space S, the cylinder 100 can store energy by reducing the volume of space S, that is, by reducing the volume of the medium 130. Conversely, when the medium 130 is sealed in a sealed space S, an increase in the volume of space S, that is, an increase in the volume of medium 130, causes the piston 120 to move downward inside the cylinder 110, as shown in Figure 3, allowing the cylinder 100 to use the stored energy. Note that if the spaces S of multiple cylinders 100 are connected, and the volume of space S in one cylinder 100 is reduced, but the medium 130 in one space S moves to the space S in another cylinder 100, increasing the volume of the other space S, then no energy will be stored in cylinder 100, and the energy will be used directly in the other cylinder 100. Furthermore, even if the volume of space S in one cylinder 100 is reduced, and the medium 130 in one space S moves to the space S in another cylinder 100, increasing the volume of the other space S, if the pressure of the medium 130 is kept constant, no energy will be stored in cylinder 100, and no energy will be used in the other cylinder 100. In other words, when the medium 130 moves between multiple cylinders 100 while maintaining a constant pressure, only the energy stored with the medium 130 is moved, and there is virtually no energy storage or output for the multiple cylinders 100 as a whole. The piston 120 is connected to a piston drive unit 310 (not shown) and is driven by the piston drive unit 310.Furthermore, there are no limitations on the shape of the cylinder 110 and piston 120, as long as the volume of space S can be changed, and space S may be formed as an internal space of a pump or the like.

[0028] The medium 130 is sealed in space S. Examples of the medium 130 include gases, liquids, supercritical fluids, and mixtures thereof. Examples of materials for the medium 130 include water, ethanol, diethyl ether, carbon dioxide, methane, hydrogen sulfide, hydrogen chloride, sulfur dioxide, amines, and ethanol, as well as mixtures of liquid amine and gaseous carbon dioxide, or water and gaseous carbon dioxide. By allowing the piston 120 to slide vertically inside the cylinder 110, the volume of the medium 130 sealed in space S can be changed while maintaining a near isothermal temperature. Space S may also be connected to a storage cylinder capable of storing the medium 130 or a storage cylinder that has stored the medium 130. This allows the total amount of energy stored to be increased by moving the energy-storage medium 130 in space S to the storage cylinder for storage, and by moving new medium 130 before energy storage from the storage cylinder to space S and sealing it in, and repeating these processes.

[0029] The cylinder temperature controller 140 is positioned to surround the side of the cylinder 110 and adjusts the temperature of the medium 130 in the space S via the cylinder 110 (cylinder 100). From the viewpoint of improving heat transfer, the cylinder temperature controller 140 may be embedded inside the cylinder 110, or it may be positioned in the space S of the cylinder 100 in a location that does not obstruct the movement of the piston 120. Since setting the temperature of the cylinder 100 each time it is used would result in significant energy loss, the cylinder temperature controller 140 allows the temperature of the cylinder 100 to be kept constant. Examples of the cylinder temperature controller 140 include a heat exchanger and a heat pump. The cylinder 100 may further have an insulating material surrounding the cylinder temperature controller 140. By having an insulating material in the cylinder 100, the temperature of the medium 130 in the space S can be efficiently kept constant. The cylinder temperature controller 140 may be omitted depending on the embodiment of the energy storage device. The cylinder temperature controller 140 is connected to the cylinder temperature control unit 320 and controlled by the cylinder temperature control unit 320.

[0030] In the energy storage device according to one embodiment of the present invention, there is no limit to the number of cylinders 100 that can be arranged, and the output energy can be increased by providing multiple cylinders 100. For example, as shown in Figure 4, by preparing multiple cylinders 100 and connecting the space S in parallel with piping 200 or the like, the multiple cylinders 100 can be considered as a single cylinder 100. This makes it possible to increase the maximum volume of the cylinder 100. In this case, each piston 120 may be moved simultaneously or individually.

[0031] Furthermore, a configuration in which multiple cylinders 100 are connected in parallel by piping 200 can be sealed inside another cylinder 110' together with another medium 130', as shown in Figure 5. In this case, the cylinder temperature regulator 140 is positioned not on the cylinder 110, but surrounding the side of the cylinder 110' or along its inner surface. This increases the contact area between the cylinder 100 and the heat source (the cylinder temperature regulator 140 in Figure 1, and the medium 130' heated or cooled by the cylinder temperature regulator 140 in Figure 5), thereby improving the heating or cooling rate of the medium 130 sealed inside the cylinder 110. The material of the medium 130' can be the same as that of the medium 130 described above. The material of the cylinder 110' can be the same as that of the cylinder 110 described above. The pressure resistance of cylinder 110' and cylinder 110 may be different. Cylinder 110' may be configured to have a lower pressure resistance than cylinder 110, or conversely, cylinder 110' may be configured to have a higher pressure resistance than cylinder 110.

[0032] Furthermore, as shown in Figure 6, the cylinder 100 may be a continuous piston type in which a piston 120 is inserted into a cylinder 110 with openings at one end and the other end. With a continuous piston type, multiple cylinder temperature controllers 140 can be arranged to compress and expand the medium at multiple temperature ranges in a single cylinder 100, thereby suppressing heat loss. Similar to a piston type cylinder 100, multiple continuous piston type cylinders 100 can be connected in parallel, as shown in Figures 4 and 5.

[0033] Furthermore, as shown in Figure 7, the cylinder 100 may be a hose type in which a hose 121, made of silicone rubber, nitrile butadiene rubber, fluororubber, perfluoroelastomer, etc., with one end and the other end open, is passed through the cylinder 110 from one end to the other. In the case of a hose type, for example, by closing the other end of the hose 121 and introducing a medium into the hose 121 from one end using a pressure pump or the like, the hose 121 inside the cylinder 110 can be expanded, as shown by the dotted line in Figure 7, thereby reducing the volume of the space S surrounded by the inside of the cylinder 110 and the outside of the hose 121. Then, by opening the other end of the hose 121, the medium flows out, the hose 121 inside the cylinder 110 contracts, and the volume of the space S increases. The released medium can be converted into electrical energy, for example, by a generator. The medium introduced into the hose 121 is the same as the medium 130 sealed in the space S. The hose 121 and the medium flowing into the hose 121 will function as a piston 120. The hose 121 inside the cylinder 110 may be a combination of multiple hoses 121 connected in parallel, as shown in Figure 8. Also, like the piston-type cylinder 100, the hose-type cylinder 100 can be made by connecting multiple cylinders 100 in parallel, as shown in Figures 4 and 5.

[0034] Furthermore, as shown in Figure 9, the cylinder 100 may be a bellows-type hose 122, made of silicone rubber, nitrile butadiene rubber, fluororubber, or perfluoroelastomer, with one end open and the other end bellows-shaped and closed, which is sealed inside the cylinder 110. In the case of a bellows-type hose, by introducing a medium from one end of the hose 122 using a pressure pump or the like, the bellows-shaped other end expands, as shown by the dotted line in Figure 9, thereby reducing the volume of the space S surrounded by the inside of the cylinder 110 and the outside of the hose 122. Then, by releasing the medium from one end of the hose 122, the bellows-shaped other end contracts, and the volume S of the space increases. The medium introduced into the hose 122 is the same as the medium 130 sealed in the space S. The hose 122 and the medium introduced into the hose 122 act as a piston 120. The other end of the cylinder 110, which is bellows-shaped, may be a configuration in which multiple bellows-shaped other ends are connected in parallel, as shown in Figure 10. Furthermore, like the piston-type cylinder 100, multiple bellows-type cylinders 100 can be connected in parallel, as shown in Figures 4 and 5.

[0035] Furthermore, as shown in Figure 11, the cylinder 100 may be a membrane type in which the space S is partitioned by a membrane 123 made of silicone rubber, nitrile butadiene rubber, fluororubber, and perfluoroelastomer inside the cylinder 110. In the case of a membrane type, by flowing the medium into the other space S' partitioned by the membrane 123 inside the cylinder through an opening formed in the cylinder 110, the membrane 123 moves towards space S, as shown by the dotted line in Figure 11, and the volume of space S can be reduced. Then, by flowing the medium out through the opening formed in the cylinder 110, the membrane 122 moves towards the other space S', and the volume of space S increases. The medium flowing into the other space S' is the same as the medium 130 sealed in space S. The membrane 123 and the medium flowing into the other space S' will function as a piston 120.

[0036] Furthermore, the cylinder 100 may be a two-layer type, as shown in Figure 12, in which the space S is partitioned by liquid 124 inside the cylinder 110. In the case of a two-layer type, by introducing liquid 124 into the cylinder 110, the volume of liquid 124 increases, as shown by the dotted line in Figure 12, and the volume of space S decreases. Then, by releasing the liquid 124 from inside the cylinder 110, the volume of liquid 124 decreases, and the volume of space S increases. Examples of liquid 124 include those with a higher density than the medium 130 in space S and that do not dissolve in the medium 130. Examples include perfluorocarbons such as tetradecafluorohexane, perfluoropolyethers, and ionic liquids such as 1-butyl-3-methylimidazolium hexafluorophosphate. Liquid 124 plays the role of a piston 120. Similar to the piston-type cylinder 100, multiple two-layer cylinders 100 can be connected in parallel, as shown in Figures 4 and 5.

[0037] By adjusting the temperature of the cylinder 100 using the cylinder temperature controller 140, the expansion and contraction of the hose 121, the expansion and contraction of the other end of the bellows-shaped hose 122, the movement of the membrane 123, and the expansion and contraction of the liquid 124 can be controlled. With hose-type, bellows-type, membrane-type, and double-layer systems, heat loss due to frictional resistance generated by the sliding of the piston 120 and cylinder 110 can be prevented. In addition, with hose-type, bellows-type, membrane-type, and double-layer systems, leakage of the medium 130 from the gap in the sliding part between the piston 120 and cylinder 110 can be prevented.

[0038] <First Embodiment> <<Configuration>> The configuration of the energy storage device 10 according to the first embodiment of the present invention will now be described. Figure 13 is a schematic diagram of the energy storage device 10 according to the first embodiment of the present invention. As shown in Figure 13, the energy storage device 10 comprises a first cylinder 100-1, a second cylinder 100-2, a third cylinder 100-3, piping 200, and a control unit 300 (not shown). The first cylinder 100-1, the second cylinder 100-2, and the third cylinder 100-3 have the same configuration as the cylinder 100 described above.

[0039] The first cylinder 100-1 has a first cylinder temperature controller 140-1. The second cylinder 100-2 has a second cylinder temperature controller 140-2. The third cylinder 100-3 has a third cylinder temperature controller 140-3. The first space S1 of the first cylinder 100-1 is sealed with a gas as the first medium 130-1, and the second space S2 of the second cylinder 100-2 is sealed with a liquid as the second medium 130-2. As the gas, for example, carbon dioxide can be used. As the liquid, for example, water or an amine can be used.

[0040] (Piping) The piping 200 includes a first pipe 200-1, a second pipe 200-2, a third pipe 200-3, and a branch section 210. The interior of the first pipe 200-1 is connected on one end to a first space S1 in the first cylinder 100-1, and on the other end to the interior of the branch section 210. The second pipe 200-2 is connected on one end to a second space S2 in the second cylinder 100-2, and on the other end to the interior of the branch section 210. The third pipe 200-3 is connected on one end to a third space S3 in the third cylinder 100-3, and on the other end to the interior of the branch section 210. The branch section 210 includes a storage section below which liquid is stored. At the branching section 210, the first pipe 200-1 is positioned above the second pipe 200-2 and the third pipe 200-3. The first space S1, the second space S2, and the third space S3 are connected via the first pipe 200-1, the second pipe 200-2, the third pipe 200-3, and the branching section 210. The materials for the first pipe 200-1, the second pipe 200-2, the third pipe 200-3, and the branching section 210 can be, for example, the same as those used for the cylinder 100 described above, and materials with low heat capacity are preferred.

[0041] The piping 200 includes a first valve 220-1, a second valve 220-2, and a third valve 220-3. The first valve 220-1 is located in the first piping 200-1 and opens and closes the inside of the first piping 200-1 to regulate the movement of the medium 130 inside the first piping 200-1. The second valve 220-2 is located in the second piping 200-2 and opens and closes the inside of the second piping 200-2 to regulate the movement of the medium 130 inside the second piping 200-2. The third valve 220-3 is located in the third piping 200-3 and opens and closes the inside of the third piping 200-3 to regulate the movement of the medium 130 inside the third piping 200-3. The first valve 220-1, the second valve 220-2, and the third valve 220-3 are made of the same material as the cylinder 100 described above. The first valve 220-1, the second valve 220-2, and the third valve 220-3 are connected to a valve drive unit 330 and driven by the valve drive unit 330. The first valve 220-1, the second valve 220-2, and the third valve 220-3 are used to restrict or release the movement of the medium 130, or to adjust the flow rate of the medium 130, by opening and closing them. By restricting or releasing the movement of the first piston 120-1, the second piston 120-2, and the third piston 120-3, the movement of the medium 130 can be restricted or released, and in some cases the first valve 220-1, the second valve 220-2, and the third valve 220-3 can perform the same function as the first valve 220-1, the second valve 220-2, and the third valve 220-3. In this case, the first valve 220-1, the second valve 220-2, and the third valve 220-3 can be omitted.

[0042] The piping 200 includes a second piping temperature controller 230-2 and a third piping temperature controller 230-3. The second piping temperature controller 230-2 is located between the branch section 210 and the second valve 220-2 and is positioned in a part of the second piping 200-2. The second piping temperature controller 230-2 heats or cools the medium 130 inside the second piping 200-2. The third piping temperature controller 230-3 is located between the branch section 210 and the third valve 220-3 and is positioned in a part of the third piping 200-3. The third piping temperature controller 230-3 heats or cools the medium 130 inside the third piping 200-3. Examples of the second piping temperature controller 230-2 and the third piping temperature controller 230-3 include a heat exchanger and a heat pump. In this embodiment, when energy is used, the second pipe temperature controller 230-2 and the third pipe temperature controller 230-3 follow the reverse process: when the second pipe temperature controller 230-2 heats up, the third pipe temperature controller 230-3 cools down, and when the third pipe temperature controller 230-3 heats up, the second pipe temperature controller 230-2 cools down. Therefore, energy efficiency can be increased by directly or indirectly exchanging thermal energy between the second pipe temperature controller 230-2 and the third pipe temperature controller 230-3. The second pipe temperature controller 230-2 and the third pipe temperature controller 230-3 are connected to and controlled by the pipe temperature control unit 340.

[0043] (Control Unit) As shown in Figure 14, the control unit 300 is communicatively connected to the piston drive unit 310, the cylinder temperature control unit 320, the valve drive unit 330, and the piping temperature control unit 340. Based on a pre-stored program, the control unit 300 controls the piston drive unit 310, the valve drive unit 330, the cylinder temperature control unit 320, and the piping temperature control unit 340 according to the user commands entered. By driving the piston drive unit 310, the control unit 300 moves the piston 120 and changes the volume of the partitioned space S inside the cylinder 110.

[0044] <<Operation>> The operation of the energy storage device 10 according to the first embodiment of the present invention will be described. The cases of storing energy and using the stored energy will be described respectively. It is assumed that the driving of the first piston 120-1, the second piston 120-2, and the third piston 120-3 is performed by the control unit 300 via the piston driving unit 310, and the driving of the first valve 220-1, the second valve 220-2, and the third valve 220-3 is performed via the valve driving unit 330, and the control of the first cylinder temperature regulator 140-1, the second cylinder temperature regulator 140-2, and the third cylinder temperature regulator 140-3 is performed via the cylinder temperature control unit 320, and the control of the second pipe temperature regulator 230-2 and the third pipe temperature regulator 230-3 is performed via the pipe temperature control unit 340.

[0045] (When storing energy) In FIG. 13, the first cylinder 100-1 and the second cylinder 100-2 are maintained at a pressure of the first pressure P1. The first pressure P1 is set, for example, between 1 MPa and 100 MPa. The first cylinder 100-1 is maintained at a first temperature T1 that is higher than the temperature of the second cylinder 100-2 by the first cylinder temperature regulator 140-1. The second cylinder 100-2 is maintained at a second temperature T2 by the second cylinder temperature regulator 140-2. The first temperature T1 is set, for example, between 0°C and 300°C. The second temperature T2 is set, for example, between -30°C and 50°C. A part of the second pipe 200-2 is maintained at the second temperature T2 by the second pipe temperature regulator 230-2.

[0046] Close the third valve 220-3 and open the first valve 220-1 and the second valve 220-2. In this state, as shown in FIG. 15, in the first cylinder 100-1, move the first piston 120-1 upward so that the volume of the first space S1 decreases. If there is liquid remaining in the branch portion 210 and the second pipe 200-2, release the restriction on the movement of the second piston 120-2 while maintaining the pressure, and move the remaining liquid to the second cylinder 100-2. Then, restrict the movement of the second piston 120-2 so that the second piston 120-2 does not move. Thereby, the gas in the first space S1 moves from the first space S1 to the first pipe 200-1, the branch portion 210, and the second pipe 200-2. Since the third valve 220-3 is closed, the gas does not move to the third cylinder 100-3.

[0047] The gas is cooled in the second pipe 200-2 by the second pipe temperature regulator 230-2 until the temperature reaches the second temperature T2. The cooled gas moves through the second pipe 200-2 to the second space S2 and is dissolved in the liquid.

[0048] When the gas is sufficiently dissolved in the liquid in the second space S2, close the first valve 220-1 and the second valve 220-2. Thereby, the energy storage device 10 is in a state of storing energy.

[0049] (When using energy) The first cylinder 100-1 is maintained at the first temperature T1 by the first cylinder temperature regulator 140-1. The second cylinder 100-2 is maintained at the second temperature T2 by the second cylinder temperature regulator 140-2. The third cylinder 100-3 is maintained at the second temperature T2 by the third cylinder temperature regulator 140-2. A part of the second pipe 200-2 is maintained at the first temperature T1 by the second pipe temperature regulator 230-2. A part of the third pipe 220-3 is maintained at the second temperature T2 by the third pipe temperature regulator 230-3.

[0050] The restrictions on the movement of the first piston 120-1 and the third piston 120-3 are released while maintaining the pressure. The first valve 220-1, the second valve 220-2, and the third valve 220-3 are opened. In this state, as shown in Figure 16, the second piston 120-2 is moved upward while maintaining the pressure of the liquid in the second space S2, so that the volume of the second space S2 decreases. As a result, the liquid in which the gas is dissolved in the second space S2 moves from the second space S2 to the second pipe 200-2.

[0051] The liquid is heated in the second pipe 200-2 by the second pipe temperature regulator 230-2 until its temperature reaches a first temperature T1. This causes the gas dissolved in the liquid to dissipate. The dissipated gas moves into the first space S1 above the branch section 210 and through the first pipe 200-1. The gas does not move into the third pipe 200-3. The gas moves the first piston 120-1 downward in the first cylinder 100-1 so that the volume of the first space S1 increases. The movement of the first piston 120-1 can be used as energy.

[0052] The liquid that has released the gas is temporarily stored at the branch section 210 from the second pipe 200-2 and moves to the third space S3 through the third pipe 200-3. The liquid does not move to the first pipe 200-1. In the third pipe 200-3, the liquid is cooled by the third pipe temperature controller 230-3 until its temperature reaches the second temperature T2. In the third cylinder 100-3, the liquid moves the third piston 120-3 downward so that the volume of the third space S3 increases. The movement of the third piston 120-3 can be used as energy. Energy efficiency can be increased by utilizing the thermal energy discharged in the third pipe temperature controller 230-3 in the second pipe temperature controller 230-2.

[0053] Once the predetermined liquid has moved from the second space S2 to the third space S3, the first valve 220-1, the second valve 220-2, and the third valve 220-3 are closed. Since the liquid 130-2 that was in the second space S2 has moved to the third space S3, the next time energy is to be stored, the gas will be dissolved in the liquid in the third cylinder 100-3.

[0054] <<Example>> 51.7 mol of gaseous carbon dioxide in 47 L was sealed in the first cylinder 100-1, 97.9 L of water with 47.2 mol of dissolved carbon dioxide was sealed in the second cylinder 100-2, and 1 L of water with 1 mol of dissolved carbon dioxide was sealed in the third cylinder 100-3. When storing energy, the temperature of the first cylinder 100-1 was maintained at 60°C and the pressure at 3 MPa. The temperature of the second cylinder 100-2 was maintained at 25°C and the pressure at 3 MPa. Under these conditions, the first piston 120-1 was moved upward to input 140 kJ of energy. In the second pipe temperature controller 230-2, the carbon dioxide was cooled from 60°C to 25°C by heat exchange with the atmosphere. As a result, the first cylinder 100-1 contained 1.1 mol of carbon dioxide in 1 L, and the second cylinder 100-2 contained 97.8 mol of dissolved carbon dioxide in 97.9 L of water. The third cylinder 100-3 remained unchanged.

[0055] When energy is used, the first cylinder 100-1 is maintained at a temperature of 60°C and a pressure of 3 MPa. The second cylinder 100-2 is maintained at a temperature of 25°C and a pressure of 3 MPa. The third cylinder 100-3 is maintained at a temperature of 25°C and a pressure of 3 MPa. Under these conditions, the second piston 120-2 is moved upward, inputting 295 kJ of energy. In the second pipe temperature controller 230-2, water with dissolved carbon dioxide is heated from 25°C to 60°C, and in the third pipe temperature controller 230-3, water from which carbon dioxide has been released is cooled from 60°C to 25°C. Through the exchange of thermal energy between the second pipe temperature controller 230-2 and the third pipe temperature controller 230-3, 130 kJ of energy is input to obtain gaseous carbon dioxide at 60°C. In the first cylinder 100-1, the first piston 120-1 moved downward, outputting 140 kJ of energy. In the third cylinder 100-3, the third piston 120-3 moved downward, outputting 295 kJ of energy. As a result, 51.7 mol of carbon dioxide, or 47 L, was present in the first cylinder 100-1, 1 mol of water with 1 mol of dissolved carbon dioxide was present in the second cylinder 100-2, and 97.9 L of water with 47.2 mol of dissolved carbon dioxide was present in the third cylinder 100-3.

[0056] When storing energy, 140 kJ of energy was input through the first piston 120-1. When using energy, 295 kJ of energy was input through the second piston 120-2, 130 kJ of energy was input through the second and third pipe temperature controllers 230-2 and 230-3, 140 kJ of energy was output through the first piston 120-1, and 295 kJ of energy was output through the third piston 120-3. Therefore, for an input of 140 kJ of energy, an output of 10 kJ (= -295 kJ - 130 kJ + 140 kJ + 295 kJ) was obtained, resulting in an energy storage efficiency of approximately 7% (= 10 kJ ÷ 140 kJ × 100).

[0057] <Modification of the First Embodiment> <<Configuration>> In the energy storage device 10 according to the first embodiment described above, the piping 200 has a second piping temperature regulator 230-2 and a third piping temperature regulator 230-3. However, as shown in Figure 17, the second piping temperature regulator 230-2 may be composed of a second-first piping temperature regulator 230-2-1 and a second-second piping temperature regulator 230-2-2 in order from the branching section 210, and the third piping temperature regulator 230-3 may be composed of a third-first piping temperature regulator 230-3-1 and a third-second piping temperature regulator 230-3-2 in order from the branching section 210. The second-first pipe temperature controller 230-2-1, the second-second pipe temperature controller 230-2-2, the third-first pipe temperature controller 230-3-1, and the third-second pipe temperature controller 230-3-2 are connected to and controlled by the pipe temperature control unit 340. By arranging multiple pipe temperature controllers 230, the temperature of the medium 130 can be adjusted efficiently. In this embodiment, when energy is used, when the second-first pipe temperature controller 230-2-1 and the second-second pipe temperature controller 230-2-2 are heated, the third-first pipe temperature controller 230-3-1 and the third-second pipe temperature controller 230-3-2 are cooled, following the reverse process. Furthermore, when the third-first pipe temperature controller 230-3-1 and the third-second pipe temperature controller 230-3-2 heat up, the second-first pipe temperature controller 230-2-1 and the second-second pipe temperature controller 230-2-2 cool down, following the reverse process. Therefore, energy efficiency can be increased by directly or indirectly exchanging thermal energy between the second-first pipe temperature controller 230-2-1 and the third-first pipe temperature controller 230-3-1, and between the second-second pipe temperature controller 230-2-2 and the third-second pipe temperature controller 230-3-2. The following will mainly describe the differences from the energy storage device 10 according to the first embodiment.

[0058] <<Operation>> (When storing energy) In Figure 17, the pressure of the first cylinder 100-1 and the second cylinder 100-2 is maintained at a first pressure P1. The first pressure P1 is set to, for example, between 1 MPa and 100 MPa. The temperature of the first cylinder 100-1 is maintained at a first temperature T1, which is higher than the temperature of the second cylinder 100-2, by the first cylinder temperature controller 140-1. The first temperature T1 is set to, for example, between 0°C and 300°C. The temperature of the second cylinder 100-2 is maintained at a second temperature T2, which is lower than 50°C, by the second cylinder temperature controller 140-2. The second temperature T2 is set to, for example, between -30°C and 50°C. A portion of the second piping 200-2 is kept at room temperature by the second-first piping temperature controller 230-2-1, and its temperature is kept at a second temperature T2 by the second-second piping temperature controller 230-2-2.

[0059] As shown in Figure 18, when the first piston 120-1 is moved upward in the first cylinder 100-1 so that the volume of the first space S1 decreases, the gas in the first space S1 moves from the first space S1 to the first pipe 200-1, the branch section 210, and the second pipe 200-2. Since the third valve 220-3 is closed, the gas does not move to the third cylinder 100-3. In the second pipe 200-2, the gas is cooled to room temperature by the second-first pipe temperature controller 230-2-1, and then cooled to a second temperature T2 by the second-second pipe temperature controller 230-2-2. The cooled gas moves through the second pipe 200-2 to the second space S2, where it dissolves in the liquid.

[0060] (When energy is used) The temperature of the first cylinder 100-1 is maintained at a first temperature T1 by the first cylinder temperature controller 140-1. The temperature of the second cylinder 100-2 is maintained at a second temperature T2 by the second cylinder temperature controller 140-2. The temperature of the third cylinder 100-3 is maintained at a second temperature T2 by the third cylinder temperature controller 140-3. A portion of the second piping 200-2 is maintained at room temperature by the 2-2 piping temperature controller 230-2-2, and at a first temperature T1 by the 2-1 piping temperature controller 230-2-1. A portion of the third piping 220-3 is kept at room temperature by the third-first piping temperature controller 230-3-1, and its temperature is kept at a second temperature T2 by the third-second piping temperature controller 230-3-2.

[0061] As shown in Figure 19, when the second piston 120-2 is moved upward while maintaining the liquid pressure in the second space S2, the volume of the second space S2 decreases, and the liquid containing dissolved gas in the second space S2 moves from the second space S2 to the second pipe 200-2. In the second pipe 200-2, the liquid is heated by the second-second pipe temperature controller 230-2-2 until its temperature reaches room temperature, and then heated by the second-first pipe temperature controller 230-2-1 until its temperature reaches a first temperature T1.

[0062] The liquid that has released the gas is temporarily stored at the branch section 210 from the second pipe 200-2 and moves to the third space S3 through the third pipe 200-3. The liquid does not move to the first pipe 200-1. In the third pipe 200-3, the temperature is cooled to room temperature by the third-first pipe temperature controller 230-3-1 and then cooled to a second temperature T2 by the third-second pipe temperature controller 230-3-2.

[0063] <<Example>> 51.7 mol of gaseous carbon dioxide in 47 L was sealed in the first cylinder 100-1, 29.9 L of water with 16 mol of dissolved carbon dioxide sealed in the second cylinder 100-2, and 1 L of water with 16 mol of dissolved carbon dioxide sealed in the third cylinder 100-3. When storing energy, the temperature of the first cylinder 100-1 is maintained at 60°C and the pressure at 3 MPa. The temperature of the second cylinder 100-2 is maintained at 0°C and the pressure at 3 MPa. Under these conditions, 140 kJ of energy was input by moving the first piston 120-1 upwards. In the 2-1 piping temperature controller 230-2-1, the temperature of the gas was reduced from 60°C to 25°C by heat exchange with the atmosphere, and in the 2-2 piping temperature controller, 49 kJ of energy was used to cool the gas from 25°C to 0°C. As a result, 1.1 mol of carbon dioxide and 1 L of water were present in the first cylinder 100-1, and 29.9 L of water with 66.5 mol of dissolved carbon dioxide was present in the second cylinder 100-2. The third cylinder 100-3 remained unchanged.

[0064] When using the stored energy, the first cylinder 100-1 is maintained at a temperature of 60°C and a pressure of 3 MPa. The second cylinder 100-2 is maintained at a temperature of 0°C and a pressure of 3 MPa. The third cylinder 100-3 is maintained at a temperature of 0°C and a pressure of 3 MPa. Under these conditions, the second piston 120-2 was moved upward to input 88 kJ of energy. The water with dissolved carbon dioxide was heated from 0°C to 25°C in the second-first pipe temperature controller 230-2-1, and then heated from 25°C to 60°C in the second-second pipe temperature controller 230-2-2. The water from which carbon dioxide had been released was cooled from 60°C to 25°C in the third-first pipe temperature controller 230-3-1, and then cooled from 25°C to 0°C in the third-second pipe temperature controller 230-3-2. In the second-first pipe temperature controller 230-2-1 and the third-first pipe temperature controller 230-3-1, and in the second-second pipe temperature controller 230-2-2 and the third-second pipe temperature controller 230-3-2, 68 kJ of energy was input to obtain gaseous carbon dioxide at 60°C by exchanging thermal energy. In the first cylinder 100-1, the first piston 120-1 moved downward and output 140 kJ of energy. In the third cylinder 100-3, the third piston 120-3 moved downward and output 88 kJ of energy. As a result, the first cylinder 100-1 contained 51.7 mol of carbon dioxide in 47 L, the second cylinder 100-2 contained 1 L of water with 16 mol of dissolved carbon dioxide, and the third cylinder 100-3 contained 29.9 L of water with 16 mol of dissolved carbon dioxide.

[0065] When storing energy, 140 kJ of energy was input by the first piston, and 49 kJ of energy was input by the second-second pipe temperature controller 230-2-2. When using energy, 88 kJ of energy was input by the second piston, and 68 kJ of energy was input by the second-first pipe temperature controller 230-2-1, the second-second pipe temperature controller 230-2-2, the third-first pipe temperature controller 230-3-1, and the third-second pipe temperature controller 230-3-2. 140 kJ of energy was output by the first piston, and 88 kJ of energy was output by the third piston 120-3. Therefore, with an energy input of 189 kJ (= 140 kJ + 49 kJ), the energy output is 72 kJ (= -88 kJ - 68 kJ + 140 kJ + 88 kJ), resulting in an energy storage efficiency of approximately 38% (= 72 kJ ÷ 189 kJ × 100).

[0066] <Second Embodiment> <<Configuration>> The configuration of the energy storage device 20 according to the second embodiment of the present invention will now be described. Figure 20 is a schematic diagram of the energy storage device 20 according to the second embodiment of the present invention. As shown in Figure 20, the energy storage device 20 includes a first cylinder 100-1, a second cylinder 100-2, a third cylinder 100-3, a fourth cylinder 100-4, piping 200, and a control unit 300 (not shown). The first cylinder 100-1, the second cylinder 100-2, the third cylinder 100-3, and the fourth cylinder 100-4 have the same configuration as the cylinder 100 described above. The maximum volumes of the second cylinder 100-2 and the fourth cylinder 100-4 are greater than the maximum volumes of the first cylinder 100-1 and the third cylinder 100-3. Furthermore, if the total maximum volume of the second cylinder 100-2 and the fourth cylinder 100-4 is greater than the total maximum volume of the first cylinder 100-1 and the third cylinder 100-3, then each of the first cylinder 100-1, the second cylinder 100-2, the third cylinder 100-3, and the fourth cylinder 100-4 may be configured by connecting multiple cylinders 100 in parallel, as shown in Figure 4, to increase the maximum volume. The fourth space S4 of the fourth cylinder 100-4 is filled with the medium 130.

[0067] (Piping) Piping 200 includes a first pipe 200-1, a second pipe 200-2, a third pipe 200-3, and a fourth pipe 200-4. One end of the first pipe 200-1 leads to the first space S1 in the first cylinder 100-1, and the other end leads to the second space S2 in the second cylinder 100-2. The first pipe 200-1 connects the first space S1 and the second space S2. One end of the second pipe 200-2 leads to the second space S2, and the other end leads to the third space S3 in the third cylinder 100-3. The second pipe 200-2 connects the second space S2 and the third space S3. The interior of the third pipe 200-3 is connected on one end to the third space S3 and on the other end to the fourth space S4 in the fourth cylinder 100-4. The third pipe 200-3 connects the third space S3 and the fourth space S4. The interior of the fourth pipe 200-4 is connected on one end to the fourth space S4 and on the other end to the first space S1. The fourth pipe 200-4 connects the fourth space S4 and the first space S1. Examples of materials for the first pipe 200-1, the second pipe 200-2, the third pipe 200-3 and the fourth pipe 200-4 include the same materials as those used for the cylinder 100 described above.

[0068] The piping 200 includes a first valve 220-1, a second valve 220-2, a third valve 220-3, and a fourth valve 220-4. The first valve 220-1 is located in the first piping 200-1 and opens and closes the inside of the first piping 200-1 to regulate the movement of the medium 130 inside the first piping 200-1. The second valve 220-2 is located in the second piping 200-2 and opens and closes the inside of the second piping 200-2 to regulate the movement of the medium 130 inside the second piping 200-2. The third valve 220-3 is located in the third piping 200-3 and opens and closes the inside of the third piping 200-3 to regulate the movement of the medium 130 inside the third piping 200-3. The fourth valve 220-4 is located in the fourth pipe 200-4 and opens and closes the inside of the fourth pipe 200-4 to adjust the movement of the medium 130 inside the fourth pipe 200-4. The material of the first valve 220-1, the second valve 220-2, the third valve 220-3, and the fourth valve 220-4 can be, for example, the same as that of the cylinder 100 described above. The first valve 220-1, the second valve 220-2, the third valve 220-3, and the fourth valve 220-4 are connected to a valve drive unit 330 and driven by the valve drive unit 330. The first valve 220-1, the second valve 220-2, the third valve 220-3, and the fourth valve 220-4 are used to restrict or release the movement of the medium 130, or to adjust the flow rate of the medium 130, by opening and closing them. Furthermore, by restricting or releasing the movement of the first piston 120-1, the second piston 120-2, the third piston 120-3, and the fourth piston 120-4, the movement of the medium 130 can be restricted or released, and in some cases, the same functions as the first valve 220-1, the second valve 220-2, the third valve 220-3, and the fourth valve 220-4 can be performed. In this case, the first valve 220-1, the second valve 220-2, the third valve 220-3, and the fourth valve 220-4 can be omitted.

[0069] (Control Unit) As shown in Figure 21, the control unit 300 is communicatively connected to the piston drive unit 310 and the valve drive unit 330. Based on a pre-stored program, the control unit 300 controls the piston drive unit 310 and the valve drive unit 330 according to user commands entered.

[0070] <<Operation>> The operation of the energy storage device 20 according to the second embodiment of the present invention will be described. The operation when storing energy and when using the stored energy will be described separately. The energy storage device 20 is assumed to be placed in a space at 30°C without temperature control. Furthermore, the first piston 120-1, the second piston 120-2, the third piston 120-3 and the fourth piston 120-4 are driven by the piston drive unit 310, and the first valve 220-1, the second valve 220-2, the third valve 220-3 and the fourth valve 220-4 are driven by the control unit 300 via the valve drive unit 330.

[0071] (When storing energy) In Figure 20, the fourth space S4 of the fourth cylinder 100-4 is filled with a medium 130, and the pressure in the fourth cylinder 100-4 is maintained at a fourth pressure P4. The fourth pressure P4 is set to, for example, between 0.1 MPa and 50 MPa.

[0072] The restriction on the movement of the first piston 120-1 is released while maintaining the pressure, allowing the first piston 120-1 to move. The first valve 220-1 is closed and the fourth valve 220-4 is opened. In this state, as shown in Figure 22, the fourth piston 120-4 is moved upward while maintaining the pressure of the medium 130, so that the volume of the fourth space S4 decreases. As a result, the medium 130 moves from the fourth space S4 to the first space S1 via the fourth pipe 200-4. In the first cylinder 100-1, the first piston 120-1 moves downward so that the volume of the first space S1 increases due to the movement of the medium 130.

[0073] Once a predetermined amount of medium 130 has moved into the first space S1 of the first cylinder 100-1, the movement of the fourth piston 120-4 is restricted while maintaining the pressure, and the fourth valve 220-4 is closed. In this state, as shown in Figure 23, the first piston 120-1 is moved upward so that the volume of the first space S1 decreases. The medium 130 in the first space S1 is pressurized until the pressure reaches the first pressure P1. The first pressure P1 is set, for example, between 1 MPa and 100 MPa. Although the temperature of the medium 130 in the first space S1 rises due to the decrease in volume of the first space S1, heat exchange with the atmosphere brings the temperature of the medium 130 to 30°C and the pressure decreases from the first pressure P1 to the second pressure P2. The second pressure P2 is set, for example, between 1 MPa and 100 MPa.

[0074] The restriction on the movement of the second piston 100-2 is released while maintaining the pressure. The second valve 220-2 is closed and the first valve 220-1 is opened. In this state, as shown in Figure 24, the first piston 120-1 is moved upward so that the volume of the first space S1 decreases while maintaining the pressure of the medium 130 in the first space S1. As a result, the medium 130 moves from the first space S1 to the second space S2 via the first pipe 200-1. In the second cylinder 100-2, the second piston 120-2 moves downward.

[0075] Once a predetermined amount of the medium 130 has moved into the second space S2, the movement of the second piston 120-2 is restricted while maintaining the pressure, and the first valve 220-1 is closed. As a result, the energy storage device 20 enters a state of energy storage. By repeating these steps, a large amount of energy can be stored in the second cylinder 100-2.

[0076] (When using energy) The pressure in the fourth cylinder 100-4 is maintained at the fourth pressure P4. The restriction on the movement of the third piston 120-3 is released while maintaining the pressure. The third valve 220-3 is closed and the second valve 220-2 is opened. In this state, as shown in Figure 25, the second piston 120-2 is moved upward while maintaining the pressure of the medium 130 so that the volume of the second space S2 decreases. Once a predetermined amount of medium 130 has moved from the second space S2 to the third space S3 via the second pipe 200-2, the second valve 220-2 is closed to restrict the movement of the second piston 120-2. Then, by releasing the pressure maintenance of the third piston 120-3, the medium 130 in the third cylinder 100-3 moves the third piston 120-3 downward so that the volume of the third space S3 increases. The pressure of the medium 130 decreases from a second pressure P2 to a third pressure P3. The third pressure P3 is set, for example, between 0.1 MPa and 50 MPa. This allows the movement of the third piston 120-3 to be used as energy. Due to the increase in the volume of the third space S3, the temperature of the medium 130 in the third space S3 decreases from 30°C, but due to heat exchange with the atmosphere, the temperature of the medium 130 is brought back to 30°C and the pressure rises to a fourth pressure P4. The fourth pressure P4 is set, for example, between 0.1 MPa and 50 MPa.

[0077] When recovering the medium 130 from the third cylinder 100-3 into the fourth cylinder 100-4, the restriction on the movement of the fourth piston 120-4 is released while maintaining the pressure. The fourth valve 220-4 is closed and the third valve 220-3 is opened. In this state, as shown in Figure 26, the third piston 120-3 is moved upward so that the volume of the third space S3 decreases while maintaining the pressure of the medium 130 in the third space S3. As a result, the medium 130 moves from the third space S3 to the fourth space S4 via the third pipe 200-3. Overall, the medium 130 moves sequentially through the fourth space S4, the first space S1, the second space S2, and the third space S3 via the fourth pipe 200-4, the first pipe 200-1, the second pipe 200-2, and the third pipe 200-3. Furthermore, the first cylinder 100-1 and the third cylinder 100-3 have common functions. For this reason, the medium 130 may be moved sequentially through the fourth space S4, first space S1, second space S2, first space S1, fourth space S4 (second space S2, third space S3, fourth space S4, third space S3, second space S2) via the fourth pipe 200-4 and the first pipe 200-1 (second pipe 200-2 and third pipe 200-3). Alternatively, in a configuration that does not include either the first cylinder 100-1 or the third cylinder 100-3, the medium 130 may be moved sequentially through the fourth space S4, the first space S1, the second space S2, the first space S1, the fourth space S4 (second space S2, third space S3, fourth space S4, third space S3, second space S2) via the fourth pipe 200-4 and the first pipe 200-1 (second pipe 200-2 and third pipe 200-3). In this case, the fourth cylinder 100-4, the first cylinder 100-1, and the second cylinder 100-2 (the second cylinder 100-3, the third cylinder 100-3, and the fourth cylinder 100-4) may be read as the first cylinder 100-1, the second cylinder 100-2, and the third cylinder 100-3, respectively.

[0078] <<Example>> Carbon dioxide at a temperature of 30°C and a pressure of 3 MPa was sealed in the fourth cylinder 100-4. When storing energy, the first cylinder 100-1 is maintained at a temperature of 30°C and a pressure of 3 MPa. The fourth piston 120-4 was moved to transfer carbon dioxide from the fourth cylinder 100-4 to the first cylinder 100-1, sealing 2.47 kg of gaseous carbon dioxide into the first cylinder 100-1. In the first cylinder 100-1, the first piston 120-1 was moved upward to input 242 kJ of energy. In the first cylinder 100-1, the carbon dioxide's temperature rose to 160°C and pressure to 18 MPa, but due to heat exchange with the atmosphere, its temperature decreased to 30°C and pressure to 6.9 MPa. Then, carbon dioxide at a temperature of 30°C and a pressure of 6.9 MPa was stored in the second cylinder 100-2.

[0079] When energy is used, the pressure in the second cylinder 100-2 is maintained at 6.9 MPa. The second piston 120-2 is moved to transfer carbon dioxide from the second cylinder 100-2 to the third cylinder 100-3, and 2.47 kg of gaseous carbon dioxide is sealed in the third cylinder 100-3. Then, in the third cylinder 100-3, the third piston 120-3 moves downward, outputting 165 kJ of energy. In the third cylinder 100-3, the temperature of the carbon dioxide dropped to -10°C and the pressure to 2.5 MPa, but due to heat exchange with the atmosphere, the temperature rose to 30°C and the pressure to 3 MPa.

[0080] When storing energy, 242 kJ of energy was input by the first piston 120-1. When using energy, 165 kJ of energy was output by the third piston 120-3. Therefore, with an input of 242 kJ of energy, the output was 165 kJ, resulting in an energy storage efficiency of approximately 68% (= 165 kJ ÷ 242 kJ × 100).

[0081] <Modification 1 of the Second Embodiment> <<Configuration>> In the energy storage device 20 according to the second embodiment described above, temperature adjustment was not performed. However, as shown in Figure 27, the first cylinder 100-1 may further have a first cylinder temperature regulator 140-1 for adjusting the temperature of the first cylinder 100-1, the second cylinder 100-2 may further have a second cylinder temperature regulator 140-2 for adjusting the temperature of the second cylinder 100-2, the third cylinder 100-3 may further have a third cylinder temperature regulator 140-3 for adjusting the temperature of the third cylinder 100-3, and the fourth cylinder 100-4 may further have a fourth cylinder temperature regulator 140-4 for adjusting the temperature of the fourth cylinder 100-4. The following will mainly describe the differences from the energy storage device 20 according to the second embodiment.

[0082] (Control Unit) As shown in Figure 28, the control unit 300 is communicatively connected to the cylinder temperature control unit 320. Based on a pre-stored program, the control unit 300 controls the piston drive unit 310, the valve drive unit 330, and the cylinder temperature control unit 320 according to the user's input.

[0083] (When storing energy) In Figure 27, the fourth space S4 of the fourth cylinder 100-4 is filled with a medium 130, and the pressure in the fourth cylinder 100-4 is maintained at a fourth pressure P4. The fourth pressure P4 is set to, for example, between 0.1 MPa and 50 MPa. The temperature of the fourth cylinder 100-4 is maintained at a fourth temperature T4 by the fourth cylinder temperature regulator 140-4. The temperatures of the first cylinder 100-1, the second cylinder 100-2, and the third cylinder 100-3 are maintained at a fourth temperature T4 by the first cylinder temperature regulator 140-1, the second cylinder temperature regulator 140-2, and the third cylinder temperature regulator 140-3, respectively. The fourth temperature T4 is set to, for example, between -30°C and 300°C.

[0084] Once a predetermined amount of medium 130 has moved from the fourth cylinder 120-4 to the first space S1 of the first cylinder 100-1, the movement of the fourth piston 120-4 is restricted while maintaining the pressure, and the fourth valve 220-4 is closed. In this state, as shown in Figure 29, the first piston 120-1 is moved upward so that the volume of the first space S1 decreases. The medium 130 in the first space S1 is pressurized until the pressure reaches the first pressure P1. Although the temperature of the medium 130 in the first space S1 tends to rise due to the decrease in the volume of the first space S1, the temperature of the first cylinder 100-1 is maintained at the fourth temperature T4 by the first cylinder temperature regulator 140-1. The thermal energy discharged in the first cylinder temperature regulator 140-1 may be stored in, for example, a heat storage tank and used in the third cylinder temperature regulator 140-3. Since the temperature of the medium 130 is maintained at the fourth temperature T4, the pressure remains at the first pressure P1. The movement of the medium 130 from the first space S1 in the first cylinder 100-1 to the second space S2 in the second cylinder 100-2 is carried out in the same manner as in the second embodiment described above. The second cylinder 100-2 can store energy at a higher pressure than in the second embodiment described above.

[0085] (When energy is used) The second cylinder 100-2 is kept at a first pressure P1, and its temperature is kept at a fourth temperature T4 by the second cylinder temperature regulator 140-2. The temperatures of the third cylinder 100-3 and the fourth cylinder 100-4 are kept at a fourth temperature T4 by the third cylinder temperature regulator 140-3 and the fourth cylinder temperature regulator 140-4, respectively.

[0086] The restriction on the movement of the third piston 120-3 is released while maintaining the pressure. The third valve 220-3 is closed and the second valve 220-2 is opened. In this state, as shown in Figure 30, the second piston 120-2 is moved upward while maintaining the pressure of the medium 130, so as to decrease the volume of the second space S2. As a result, the medium 130 moves from the second space S2 to the third space S3 via the second pipe 200-2. In the third cylinder 100-3, the medium 130 moves the third piston 120-3 downward so as to increase the volume of the third space S3. Although the temperature of the medium 130 in the third space S3 tends to decrease due to the increase in the volume of the third space S3, the third cylinder temperature regulator 140-3 allows the third cylinder 100-3 to be maintained at a fourth temperature T4. The thermal energy used in the third cylinder temperature controller 140-3 can utilize the thermal energy discharged from the first cylinder temperature controller 140-1. The first cylinder 100-1 and the third cylinder 100-3 have common functions. Therefore, without using either the first cylinder 100-1 or the third cylinder 100-3, the medium 130 may be moved sequentially through the fourth space S4, first space S1, second space S2, first space S1, fourth space S4 (second space S2, third space S3, fourth space S4, third space S3, second space S2) via the fourth pipe 200-4 and the first pipe 200-1 (second pipe 200-2 and third pipe 200-3). Alternatively, in a configuration that does not include either the first cylinder 100-1 or the third cylinder 100-3, the medium 130 may be moved sequentially through the fourth space S4, first space S1, second space S2, first space S1, fourth space S4 (second space S2, third space S3, fourth space S4, third space S3, second space S2) via the fourth pipe 200-4 and the first pipe 200-1 (second pipe 200-2 and third pipe 200-3).

[0087] <<Example>> Carbon dioxide at a temperature of 60°C and a pressure of 3 MPa was sealed in the fourth cylinder 100-4. When storing energy, the fourth cylinder 100-4 is maintained at a temperature of 60°C and a pressure of 3 MPa. The first cylinder 100-1 and the second cylinder 100-2 are maintained at a temperature of 60°C. Then, the fourth piston 120-4 was moved to transfer carbon dioxide from the fourth cylinder 100-4 to the first cylinder 100-1, sealing 2.24 kg of gaseous carbon dioxide into the first cylinder 100-1. In the first cylinder 100-1, the first piston 120-1 was moved upward to input 255 kJ of energy. In the first cylinder 100-1, the pressure of the carbon dioxide rose to 18 MPa. The carbon dioxide was kept at a temperature of 60°C by the first pipe temperature regulator 100-1. The 666 kJ of thermal energy at a temperature of 60°C discharged by the first pipe temperature regulator 100-1 was stored in the heat storage tank. Then, carbon dioxide at a temperature of 60°C and a pressure of 18 MPa was stored in the second cylinder 100-2.

[0088] When energy is used, the second cylinder 100-2 is maintained at a temperature of 60°C and a pressure of 18 MPa. The third cylinder 100-3 and the fourth cylinder 100-4 are maintained at a temperature of 60°C. The second piston 120-2 is moved to transfer carbon dioxide from the second cylinder 100-2 to the third cylinder 100-3, sealing 2.24 kg of gaseous carbon dioxide into the third cylinder 100-3. In the third cylinder 100-3, the third piston 120-3 moves downward, outputting 255 kJ of energy. In the third cylinder 100-3, the pressure of the carbon dioxide drops to 3 MPa. The temperature of the carbon dioxide is maintained at 60°C by the third cylinder temperature regulator 140-3. The third cylinder temperature controller 140-3 utilized 666 kJ of thermal energy at a temperature of 60°C discharged from the first cylinder temperature controller 140-1.

[0089] When storing energy, 255 kJ of energy was input by the first piston 120-1. When using energy, 255 kJ of energy was output by the third piston 120-3. Therefore, with an input of 255 kJ of energy, an output of 255 kJ was obtained, resulting in an energy storage efficiency of 100% (= 255 kJ ÷ 255 J × 100).

[0090] <Modification 2 of the Second Embodiment> <<Configuration>> In the energy storage device 20 according to Modification 1 of the Second Embodiment described above, a first cylinder 100-1, a second cylinder 100-2, a third cylinder 100-3, and a fourth cylinder 100-4 are provided. However, as shown in Figure 31, a fifth cylinder 100-5 can be further provided between the third cylinder 100-3 and the fourth cylinder 100-4. The fifth cylinder 100-5 has the same configuration as the cylinder 100 described above. The maximum volume of the fifth cylinder 100-5 is smaller than the maximum volume of the second cylinder 100-2 and the fourth cylinder 100-4. Also, as shown in Figure 31, the fifth cylinder 100-5 further has a fifth cylinder temperature controller 140-5 for adjusting the temperature of the fifth cylinder 100-5. The following will mainly describe the differences from Modification 1 of the energy storage device 20 according to the second embodiment.

[0091] (Piping) The piping 200 includes a first pipe 200-1, a second pipe 200-2, a third-first pipe 200-3-1, a third-second pipe 200-3-2, and a fourth pipe 200-4. One end of the third-first pipe 200-3-1 leads to the third space S3 in the third cylinder 100-3, and the other end leads to the fifth space S5 in the fifth cylinder 100-5. One end of the third-second pipe 200-3-2 leads to the fifth space S5, and the other end leads to the fourth space S4 in the fourth cylinder 100-4. Examples of materials for the third-first pipe 200-3-1 and the third-second pipe 200-3-2 include the same materials as those used for the cylinder 100 described above.

[0092] The piping 200 includes a first valve 220-1, a second valve 220-2, a third-first valve 220-3-1, a third-second valve 220-3-2, and a fourth valve 220-4. The third-first valve 220-3-1 is located in the third-first piping 200-3-1 and opens and closes the inside of the third-first piping 200-3-1 to regulate the movement of the medium 130 inside the third-first piping 200-3-1. The third-second valve 220-3-2 is located in the third-second piping 220-3-2 and opens and closes the inside of the third-second piping 220-3-2 to regulate the movement of the medium 130 inside the third-second piping 220-3-2. The material of valve 220-3-1 of the third-first valve and valve 220-3-2 of the third-second valve can be, for example, the same material as that of the cylinder 100 described above. Valves 220-3-1 of the third-first valve and valve 220-3-2 of the third-second valve are connected to and driven by valve drive unit 330. The first valve 220-1, the second valve 220-2, the third-first valve 220-3-1, the third-second valve 220-3-2, and the fourth valve 220-4 are used to restrict or release the movement of the medium 130, or to adjust the flow rate of the medium 130, by opening and closing them. Furthermore, by restricting or releasing the movement of the first piston 120-1, the second piston 120-2, the third piston 120-3, the fourth piston 120-4, and the fifth piston 120-5, the movement of the medium 130 can be restricted or released, and in some cases, the same functions as the first valve 220-1, the second valve 220-2, the third-first valve 220-3-1, the third-second valve 220-3-2, and the fourth valve 220-4 can be omitted.

[0093] <<Operation>> (When storing energy) In Figure 31, the fourth space S4 of the fourth cylinder 100-4 is filled with a medium 130, and the pressure in the fourth cylinder 100-4 is maintained at a fourth pressure P4. The fourth pressure P4 is set to, for example, between 0.1 MPa and 50 MPa. The temperature of the fourth cylinder 100-4 is set to a fourth temperature T4 by the fourth cylinder temperature controller 140-4. The fourth temperature T4 is set to, for example, between -30°C and 200°C. The first cylinder 100-1 and the second cylinder 100-2 are set to the fourth temperature T4 by the first cylinder temperature controller 140-1 and the second cylinder temperature controller 140-2, respectively.

[0094] Once a predetermined amount of medium 130 has moved from the fourth cylinder 100-4 to the first space S1 of the first cylinder 100-1, the movement of the fourth piston 120-4 is restricted while maintaining the pressure, and the fourth valve 220-4 is closed. In this state, as shown in Figure 32, the first piston 120-1 is moved upward so that the volume of the first space S1 decreases. The medium 130 in the first space S1 is pressurized until the pressure reaches a first pressure P1. The first pressure P1 is set, for example, between 1 MPa and 100 MPa. Although the temperature of the medium 130 in the first space S1 tends to rise due to the decrease in the volume of the first space S1, the first cylinder temperature regulator 140-1 maintains the temperature of the first cylinder 100-1 at a fourth temperature T4.

[0095] (When energy is used) The second cylinder 100-2 is kept at a first pressure P1 and its temperature is set to a fourth temperature T4 by the second cylinder temperature regulator 140-2. The fourth cylinder 100-4 and the fifth cylinder 100-5 are each set to a fourth temperature T4 by the fourth cylinder temperature regulator 140-4 and the fifth cylinder temperature regulator 140-5, respectively. The third cylinder 100-3 is kept at a third temperature T3, which is higher than the fourth temperature T4, by the third cylinder temperature regulator 140-3. The third temperature T3 is set, for example, between 0°C and 300°C.

[0096] The restriction on the movement of the third piston 120-3 is released while maintaining the pressure. The third valve 220-3-1 is closed and the second valve 220-2 is opened. In this state, as shown in Figure 33, the second piston 120-2 is moved upward while maintaining the pressure of the medium 130 so that the volume of the second space S2 decreases. Once a predetermined amount of medium 130 has moved from the second space S2 to the third space S3 via the second pipe 200-2, the second valve 220-2 is closed to restrict the movement of the third piston 120-3. Then, in the third cylinder 100-3, the temperature of the medium 130 is raised to the third temperature T3, and the restriction on the movement of the third piston 120-3 is released, causing the medium 130 to move the third piston 120-3 downward so that the volume of the third space S3 increases. This allows the movement of the third piston 120-3 to be used as energy. The pressure of the medium 130 is set to a third pressure P3. The third pressure P3 is set, for example, between 0.1 MPa and 50 MPa.

[0097] The restriction on the movement of the fifth piston 120-5 is released while maintaining the pressure. The third-second valve 220-3-2 is closed, and the third-first valve 220-3-1 is opened. In this state, as shown in Figure 34, the third piston 120-3 is moved upward while maintaining the pressure of the medium 130, so that the volume of the third space S3 decreases. As a result, the medium 130 moves from the third space S3 to the fifth space S5 via the third-first pipe 220-3-1.

[0098] In the fifth cylinder 100-5, the medium 130 moves the fifth piston 120-5 downward so that the volume of the fifth space S5 increases. The temperature of the medium 130 is adjusted to the fourth temperature T4 by the fifth cylinder temperature regulator 140-5. When the temperature of the medium reaches the fourth temperature T4, the pressure of the medium 130 becomes lower than the fourth pressure P4. Therefore, as shown in Figure 35, by moving the fifth cylinder 120-5 upward in the fifth cylinder 100-5 so that the volume of the fifth space S5 decreases, the pressure of the medium 130 can be made the same as the fourth pressure P4 in the fourth cylinder. The fifth cylinder 100-5 is used to make the pressure of the medium 130 the same as the pressure of the fourth cylinder 100-4, and can be omitted if the pressure and output of the other cylinders 100 can be adjusted. Furthermore, the first cylinder 100-1 and the third cylinder 100-3 share common functions. For this reason, the medium 130 may be moved sequentially through the fourth space S4, the first space S1, the second space S2, the first space S1, the fourth space S4 (or the second space S2, the third space S3, the fifth space S5, the fourth space S4, the fifth space S5, the third space S3, the second space S2) via the fourth pipe 200-4 and the first pipe 200-1 (or the second pipe 200-2, the third-first pipe 200-3-1, and the third-second pipe 200-3-2). Furthermore, the configuration may be such that the first cylinder 100-1 and any of the groups of the third cylinder 100-3 and the fifth cylinder 100-5 are not included, and the medium 130 as a whole may be moved sequentially through the fourth space S4, the first space S1, the second space S2, the first space S1, the fourth space S4 (or the second space S2, the third space S3, the fifth space S5, the fourth space S4, the fifth space S5, the third space S3, the second space S2) through the fourth pipe 200-4 and the first pipe 200-1 (or the second pipe 200-2, the third-first pipe 200-3-1, and the third-second pipe 200-3-2).

[0099] <<Example>> Carbon dioxide at a temperature of 30°C and a pressure of 3 MPa was sealed in the fourth cylinder 100-4. When storing energy, the fourth cylinder 100-4 is maintained at a temperature of 30°C and a pressure of 3 MPa. The fourth piston 120-4 was moved to transfer carbon dioxide from the fourth cylinder 100-4 to the first cylinder 100-1, sealing 2.47 kg of gaseous carbon dioxide into the first cylinder 100-1. The temperature of the first cylinder 100-1 and the second cylinder 100-2 was set to 30°C. In the first cylinder 100-1, the first piston 120-1 was moved upward to input 223 kJ of energy. In the first cylinder 100-1, the pressure of carbon dioxide rose to 18 MPa. The temperature of the carbon dioxide was maintained at 30°C by the first cylinder temperature regulator 140-1. 773 kJ of thermal energy at a temperature of 30°C was released from the first cylinder temperature regulator 140-1. Then, carbon dioxide at a temperature of 30°C and a pressure of 18 MPa was stored in the second cylinder 100-2.

[0100] When energy is used, the second cylinder 100-2 is maintained at a temperature of 30°C and a pressure of 18 MPa. The third cylinder 120-3 is maintained at a temperature of 60°C. The fourth cylinder 100-4 and the fifth cylinder 100-5 are maintained at a temperature of 30°C. The second piston 120-2 is moved to transfer carbon dioxide from the second cylinder 100-2 to the third cylinder 100-3, sealing 2.47 kg of gaseous carbon dioxide into the third cylinder 100-3. In the third cylinder 100-3, the temperature of the carbon dioxide is raised to 60°C, and the pressure rises to 36 MPa. Then, in the third cylinder 100-3, the third piston 120-3 moves downward, outputting 300 kJ of energy. In the third cylinder 100-3, the pressure of the carbon dioxide decreases to 3 MPa. The temperature of the carbon dioxide was maintained at 60°C by the third cylinder temperature regulator 140-3. The third cylinder temperature regulator 140-3 utilized 932 kJ of thermal energy emitted from other equipment.

[0101] In the fifth cylinder 100-5, the temperature of the carbon dioxide drops to 30°C, causing the pressure to drop to 2.8 MPa. Therefore, while maintaining the temperature at 30°C using the fifth cylinder temperature regulator 140-5, the fifth piston 120-5 was moved upward, inputting 14 kJ of energy, and the pressure of the carbon dioxide was set to 3 MPa, the same as in the fourth cylinder 100-4. 95 kJ of thermal energy was released in the fifth cylinder temperature regulator 140-5.

[0102] When storing energy, 223 kJ of energy was input through the first piston 120-1. When using energy, 300 kJ of energy was output through the third piston 120-3, and 14 kJ of energy was input through the fifth piston 120-5. Therefore, with an input of 223 kJ of energy, an output of 286 kJ (= 300 kJ - 14 kJ) was obtained, resulting in an energy storage efficiency of approximately 128% (= 286 kJ ÷ 223 kJ × 100).

[0103] <Modification 3 of the Second Embodiment> <<Configuration>> In the energy storage device 20 according to Modification 2 of the Second Embodiment described above, a first cylinder 100-1, a second cylinder 100-2, a third cylinder 100-3, a fourth cylinder 100-4, and a fifth cylinder 100-5 are provided. However, as shown in Figure 36, a sixth cylinder 100-6 may be provided between the first cylinder 100-1 and the second cylinder 100-2, a seventh cylinder 100-7 between the second cylinder 100-2 and the third cylinder 100-3, and an eighth cylinder 100-8 between the fourth cylinder 100-4 and the first cylinder 100-1. The sixth cylinder 100-6, the seventh cylinder 100-7, and the eighth cylinder 100-8 have the same configuration as the cylinder 100 described above. The maximum volumes of the sixth cylinder 100-6, the seventh cylinder 100-7, and the eighth cylinder 100-8 are smaller than the maximum volumes of the second cylinder 100-2 and the fourth cylinder 100-4. The following mainly describes the differences between this modified example 2 of the energy storage device 20 according to the second embodiment.

[0104] (Piping) Piping 200 includes the first-first pipe 200-1-1, the first-second pipe 200-1-2, the second-first pipe 200-2-1, the second-second pipe 200-2-2, the third-first pipe 200-3-1, the third-second pipe 200-3-2, the fourth-first pipe 200-4-1, and the fourth-second pipe 200-4-2. One end of the first-first pipe 200-1-1 leads to the first space S1 in the first cylinder 100-1, and the other end leads to the sixth space S6 in the sixth cylinder 100-6. One end of the first-second pipe 200-1-2 leads to the sixth space S6, and the other end leads to the second space S2 in the second cylinder 100-2. The second-first pipe 200-2-1 has one end leading to the second space S2 and the other end leading to the seventh space S7 in the seventh cylinder 100-7. The second-second pipe 200-2-2 has one end leading to the seventh space S7 and the other end leading to the third space S3 in the third cylinder 100-3. The fourth-first pipe 200-4-1 has one end leading to the fourth space S4 and the other end leading to the eighth space S8 in the eighth cylinder 100-8. The fourth-second pipe 200-4-2 has one end leading to the eighth space S8 and the other end leading to the first space S1. Examples of materials for the piping 1-1 200-1-1, the piping 1-2 200-1-2, the piping 2-1 200-2-1, the piping 2-2 200-2-2, the piping 4-1 200-4-1, and the piping 4-2 200-4-2 include the same materials as those used for the cylinder 100 described above.

[0105] The piping 200 includes a first-first valve 220-1-1, a first-second valve 220-1-2, a second-first valve 220-2-1, a second-second valve 220-2-2, a third-first valve 220-3-1, a third-second valve 220-3-2, a fourth-first valve 220-4-1, and a fourth-second valve 220-4-2. The first-first valve 220-1-1 is located in the first-first piping 200-1-1 and opens and closes the inside of the first-first piping 200-1-1 to adjust the movement of the medium 130 inside the first-first piping 200-1-1. The first-second valve 220-1-2 is located in the first-second pipe 200-1-2 and opens and closes the inside of the first-second pipe 200-1-2 to adjust the movement of the medium 130 inside the first-second pipe 200-1-2. The second-first valve 220-2-1 is located in the second-first pipe 200-2-1 and opens and closes the inside of the second-first pipe 200-2-1 to adjust the movement of the medium 130 inside the second-first pipe 200-2-1. The second-second valve 220-2-2 is located in the second-second pipe 200-2-2 and opens and closes the inside of the second-second pipe 200-2-2 to adjust the movement of the medium 130 inside the second-second pipe 200-2-2. Valve 4-1 220-4-1 is located in pipe 4-1 200-4-1 and opens and closes the inside of pipe 4-1 200-4-1 to adjust the movement of the medium 130 inside pipe 4-1 200-4-1. Valve 4-2 220-4-2 is located in pipe 4-2 200-4-2 and opens and closes the inside of pipe 4-2 200-4-2 to adjust the movement of the medium 130 inside pipe 202-2 200-4-2. Examples of the material for valves 1-1 220-1-1, 1-2 220-1-2, 2-1 220-2-1, 2-2 220-2-1, 4-1 220-4-1, and 4-2 220-4-2 are the same as that of the cylinder 100 described above. Valves 1-1 (220-1-1), 1-2 (220-1-2), 2-1 (220-2-1), 2-2 (220-2-1), 4-1 (220-4-1), and 4-2 (220-4-2) are connected to a valve drive unit 330 and driven by the valve drive unit 330.Valves 220-1-1 (1st-1), 220-1-2 (1st-2nd), 220-2-1 (2nd-1st), 220-2-2 (2nd-2nd), 220-3-1 (3rd-1st), 220-3-2 (3rd-2nd), 220-4-1 (4th-1st), and 220-4-2 (4th-2nd) are used to restrict or release the movement of the medium 130, or to adjust the flow rate of the medium 130, by opening and closing them. Furthermore, by restricting or releasing the movement of the first piston 120-1, the second piston 120-2, the third piston 120-3, the fourth piston 120-4, the fifth piston 120-5, the sixth piston 120-6, the seventh piston 120-7, and the eighth piston 120-8, the movement of the medium 130 can be restricted or released, and in some cases, it is possible to perform the same function as the first-first valve 220-1-1, the first-second valve 220-1-2, the second-first valve 220-2-1, the second-second valve 220-2-3, the third-first valve 220-3-1, the third-second valve 220-3-2, the fourth-first valve 220-4-1, and the fourth-second valve 220-4-2. In this case, valves 220-1-1 (1st-1), 220-1-2 (1st-2nd), 220-2-1 (2nd-1st), 220-2-2 (2nd-2nd), 220-3-1 (3rd-1st), 220-3-2 (3rd-2nd), 220-4-1 (4th-1st), and 220-4-2 (4th-2nd) can be omitted.

[0106] <<Operation>> (When storing energy) In Figure 36, the fourth space S4 of the fourth cylinder 100-4 is filled with a medium 130 and the pressure is maintained at a fourth pressure P4. The fourth pressure P4 is set to, for example, between 0.1 MPa and 50 MPa. The temperature of the fourth cylinder 100-4 is set to a fourth temperature T4 by the fourth cylinder temperature controller 140-4. The fourth temperature T4 is set to, for example, between -30°C and 200°C. The eighth cylinder 100-8, the sixth cylinder 100-6, and the second cylinder 100-2 are set to the eighth temperature T8, the sixth temperature T6, and the second temperature T2, respectively, by the eighth cylinder temperature controller 140-8, the sixth cylinder temperature controller 140-6, and the second cylinder temperature controller 140-2. The eighth temperature T8, the sixth temperature T6, and the second temperature T2 are set, for example, between -30°C and 200°C. The temperature of the first cylinder 100-1 is maintained at a first temperature T1 by the first cylinder temperature regulator 140-1. The first temperature T1 is set, for example, between 0°C and 300°C.

[0107] The restriction on the movement of the eighth piston 120-8 is released while maintaining the pressure so that the eighth piston 120-8 can move. The valve 4-2 220-4-2 is closed and the valve 4-1 220-4-1 is opened. In this state, as shown in Figure 37, the fourth piston 120-4 is moved upward while maintaining the pressure of the medium 130 so that the volume of the fourth space S4 decreases. As a result, the medium 130 moves from the fourth space S4 to the eighth space S8 via the 4-1 pipe 220-4-1. In the eighth cylinder 100-8, the eighth piston 120-8 moves downward so that the volume of the eighth space S8 increases.

[0108] Once a predetermined amount of medium 130 has moved into the eighth space S8 of the eighth cylinder 100-8, the movement of the fourth piston 120-4 is restricted, and the fourth valve 220-4-1 is closed. In this state, as shown in Figure 38, the eighth piston 100-8 is moved upward so that the volume of the eighth space S8 decreases. The pressure of the medium 130 in the eighth space S8 is set to the eighth pressure P8. The eighth pressure P8 is set, for example, between 1 MPa and 80 MPa. Although the temperature of the medium 130 in the eighth space S8 tends to rise due to the decrease in volume of the eighth space S8, the eighth cylinder temperature regulator 140-8 sets the temperature of the medium 130 to the eighth temperature T8.

[0109] The restriction on the movement of the first piston 120-1 is released while maintaining the pressure. The valve 1-1 220-1-1 is closed, and the valve 4-2 220-4-2 is opened. In this state, as shown in Figure 39, the eighth piston 120-8 is moved upward while maintaining the pressure of the medium 130, so that the volume of the eighth space S8 decreases. Once a predetermined amount of medium 130 has moved from the eighth space S8 to the first space S1 via the pipe 4-2 200-4-2, the valve 4-2 220-4-2 is closed, restricting the movement of the first piston 120-1. Then, in the first space S1, the temperature of the medium 130 is raised to a first temperature T1, and the pressure rises to a first pressure P1. The first pressure P1 is set, for example, between 1 MPa and 80 MPa.

[0110] In this state, as shown in Figure 40, the first piston 120-1 is moved upward so that the volume of the first space S1 decreases. The medium 130 in the first space S1 is pressurized until the pressure reaches the first' pressure P1'. The first' pressure P1' is set to, for example, between 2 MPa and 100 MPa. Although the temperature of the medium 130 in the first space S1 tends to rise due to the decrease in the volume of the first space S1, the first cylinder temperature regulator 140-1 keeps the temperature of the medium 130 at the first temperature T1. The thermal energy discharged by the first cylinder temperature regulator 140-1 may be stored, for example, in a heat storage tank.

[0111] The restriction on the movement of the sixth piston 120-6 is released while maintaining the pressure. The first-second valve 220-1-2 is closed, and the first-first valve 220-1-1 is opened. In this state, as shown in Figure 41, the first piston 120-1 is moved upward while maintaining the pressure of the medium 130 in the first space S1. As a result, the medium 120 moves from the first space S1 to the sixth space S6 via the first-first pipe 200-1-1.

[0112] In the sixth cylinder 100-6, the sixth piston 120-6 moves downward, and the temperature of the medium 130 is raised to the sixth temperature T6. When the temperature of the medium 130 reaches the sixth temperature T6, the pressure of the medium 130 becomes lower than the second pressure P2. Therefore, as shown in Figure 42, in the sixth cylinder 100-6, the sixth piston 120-6 is moved upward to pressurize the medium 130 until it reaches the second pressure P2. The second pressure P2 is set, for example, between 1 MPa and 80 MPa.

[0113] The restriction on the movement of the second piston 120-2 is released while maintaining the pressure. The second-first valve 220-2-1 is closed, and the first-second valve 220-1-2 is opened. In this state, as shown in Figure 43, the sixth piston 100-6 is moved upward while maintaining the pressure of the medium in the sixth space S6. As a result, the medium 130 moves from the sixth space S6 to the second space S2 via the first-second piping 200-1-2. In the second cylinder 100-2, the second piston 120-2 moves downward.

[0114] (When energy is used) The second cylinder 100-2 is kept at a second pressure P2, and its temperature is set to a second temperature T2 by the second cylinder temperature regulator 140-2. The second temperature T2 is set to, for example, between -30°C and 200°C. The fourth cylinder 100-4, the fifth cylinder 100-5, and the seventh cylinder 100-7 are set to a fourth temperature T4, a fifth temperature T5, and a seventh temperature T7, respectively, by the fourth cylinder temperature regulator 140-4, the fifth cylinder temperature regulator 140-5, and the seventh cylinder temperature regulator 140-7. The fourth temperature T4, the fifth temperature T5, and the seventh temperature T7 are set to, for example, between -30°C and 200°C. The third cylinder 100-3 is kept at a third temperature T3 by the third cylinder temperature regulator 140-3. The third temperature T3 is set, for example, between 0°C and 300°C.

[0115] The restriction on the movement of the seventh piston 120-7 is released while maintaining the pressure. The second valve 200-2-2 is closed, and the second valve 200-2-1 is opened. In this state, as shown in Figure 44, the second piston 120-2 is moved upward while maintaining the pressure of the medium 130, so as to decrease the volume of the second space S2. As a result, the medium 130 moves from the second space S2 to the seventh space S7 via the second pipe 200-2-1. In the seventh cylinder 100-7, the medium 130 moves the seventh piston 120-7 downward so as to increase the volume of the seventh space S7. As a result, the movement of the seventh piston 120-7 can be used as energy. As the volume of the seventh space S7 increases, the temperature of the medium 130 in the seventh space S7 tends to decrease, but the seventh cylinder temperature regulator 140-7 maintains the temperature of the medium 130 at the seventh temperature T7. The pressure of the medium 130 is set to the seventh pressure P7. The seventh pressure P7 is set, for example, between 0.1 MPa and 50 MPa.

[0116] The restriction on the movement of the third piston 120-3 is released while maintaining the pressure. The third valve 220-3-1 is closed and the second valve 220-2-2 is opened. In this state, as shown in Figure 45, the seventh piston 120-7 is moved upward while maintaining the pressure of the medium 130 so that the volume of the seventh space S7 decreases. Once a predetermined amount of medium 130 has moved from the seventh space S7 to the third space S3 via the second pipe 200-2-2, the second valve 220-2-2 is closed to restrict the movement of the third piston 120-3. Then, in the third cylinder 100-3, the temperature of the medium 130 is set to a third temperature T3, and the restriction on the movement of the third piston 120-3 is released, causing the medium 130 to move the third piston 120-3 downward so that the volume of the third space S3 increases. This allows the movement of the third piston 120-3 to be used as energy. Although the temperature of the medium 130 in the third space S3 tends to decrease due to the increase in the volume of the third space S3, the temperature of the medium 130 can be maintained at the third temperature T3 by the third cylinder temperature regulator 140-3. The pressure of the medium 130 is set to a third pressure P3. The third pressure P3 is set, for example, between 0.1 MPa and 50 MPa. The thermal energy used in the third cylinder temperature controller 140-3 may be obtained by, for example, a heat pump, or it may be thermal energy stored in a thermal storage tank, thermal energy discharged in the first cylinder temperature controller 140-1, or thermal energy discharged in other equipment.

[0117] The restriction on the movement of the fifth piston 120-5 is released while maintaining the pressure. The valve 3-2 220-3-2 is closed, and the valve 3-1 220-3-1 is opened. In this state, as shown in Figure 46, the third piston 120-3 is moved upward while maintaining the pressure of the medium 130, so that the volume of the third space S3 decreases. As a result, the medium 130 moves from the third space S3 to the fifth space S5 via the pipe 3-1 200-3-1.

[0118] In the fifth cylinder 100-5, the fifth piston 120-5 moves downward, and the temperature of the medium 130 is adjusted to the fifth temperature T5 by the fifth cylinder temperature regulator 140-5. When the temperature of the medium 130 reaches the fifth temperature T5, the pressure of the medium 130 becomes lower than the fourth pressure P4. Therefore, as shown in Figure 47, in the fifth cylinder 100-5, the fifth piston 120-5 is moved upward while the temperature is maintained at the fifth temperature T5 by the fifth cylinder temperature regulator 140-5, thereby pressurizing the medium 130 until its pressure reaches the fourth pressure P4, the same as the fourth cylinder. Note that the fifth cylinder 100-5 and the sixth cylinder 100-6 are for adjusting the pressure of the medium 130 to the same pressure as the fourth cylinder 100-4 or the second cylinder 100-2, and can be omitted if the pressure or output of the other cylinders 100 can be adjusted. Furthermore, the first cylinder 100-1 and the third cylinder 100-3, the eighth cylinder 100-8 and the seventh cylinder 100-7 all share common functions. For this reason, the medium 130 can be supplied without using either the group consisting of the eighth cylinder 100-8, the first cylinder 100-1 and the sixth cylinder 100-6, or the group consisting of the seventh cylinder 100-7, the third cylinder 100-3 and the fifth cylinder 100-5, using the piping 4-1 200-4-1, the piping 4-2 200-4-2, the piping 1-1 200-1-1 and the piping 1-2 200-1-2 (or the piping 2-1 200-2-1, the piping 2-2 200- It may also be moved sequentially through the piping 200-3-1 of 2-2, piping 200-3-1 of 3-1 and piping 200-3-2 of 3-2 to the fourth space S4, the eighth space S8, the first space S1, the sixth space S6, the second space S2, the sixth space S6, the first space S1, the eighth space S8, the fourth space S4 (or the second space S2, the seventh space S7, the third space S3, the fifth space S5, the fourth space S4, the fifth space S5, the third space S3, the seventh space S7, the second space S2).Furthermore, by omitting any of the groups of the eighth cylinder 100-8, the first cylinder 100-1 and the sixth cylinder 100-6, and the seventh cylinder 100-7, the third cylinder 100-3 and the fifth cylinder 100-5, the medium 130 as a whole is provided by the 4-1 piping 200-4-1, the 4-2 piping 200-4-2, the 1-1 piping 200-1-1 and the 1-2 piping 200-1-2 (or the 2-1 piping 200-2-1, the 2-2 piping It may also be moved sequentially through the piping 200-2-2, the piping 3-1 200-3-1, and the piping 3-2 200-3-2 to the fourth space S4, the eighth space S8, the first space S1, the sixth space S6, the second space S2, the sixth space S6, the first space S1, the eighth space S8, the fourth space S4 (or the second space S2, the seventh space S7, the third space S3, the fifth space S5, the fourth space S4, the fifth space S5, the third space S3, the seventh space S7, the second space S2).

[0119] <<Example>> Carbon dioxide at a temperature of 30°C and a pressure of 3 MPa was sealed in the fourth cylinder 100-4. Then, 2.47 kg of gaseous carbon dioxide was sealed in the first cylinder 100-1. When storing energy, the fourth cylinder 100-4 is maintained at a temperature of 30°C and a pressure of 3 MPa. The eighth cylinder 100-8, the sixth cylinder 100-6, and the second cylinder 100-2 are also maintained at a temperature of 30°C. The fourth piston 120-4 was moved to transfer carbon dioxide from the fourth cylinder 100-4 to the eighth cylinder 100-8, and 2.47 kg of gaseous carbon dioxide was sealed in the eighth cylinder 100-8.

[0120] The temperature of the first cylinder 100-1 was maintained at 60°C. In the eighth cylinder 100-8, the eighth piston 120-8 was moved upward to input 94 kJ of energy. The pressure of the carbon dioxide rose to 4.6 MPa. The temperature of the carbon dioxide was set to 30°C by the eighth cylinder temperature regulator 140-8. The eighth piston 120-8 was moved to transfer carbon dioxide from the eighth cylinder 100-8 to the first cylinder 100-1.

[0121] In the first cylinder 100-1, the first piston 100-1 was moved upward to input 165 kJ of energy. In the first cylinder 100-1, the pressure of carbon dioxide rose to 20 MPa. The temperature of the carbon dioxide was maintained at 60°C by the first cylinder temperature regulator 140-1. In the first cylinder temperature regulator 140-1, 513 kJ of thermal energy at a temperature of 60°C was released and stored in the heat storage tank.

[0122] In the sixth cylinder 100-6, the carbon dioxide was heated to 30°C and its pressure decreased to 8 MPa. Therefore, while maintaining the temperature at 30°C using the sixth cylinder temperature regulator 140-6, the sixth piston 120-6 was moved upward to input 7 kJ of energy, pressurizing the carbon dioxide until its pressure reached 18 MPa. The sixth piston 120-6 was moved to transfer the carbon dioxide from the sixth cylinder 100-6 to the second cylinder 100-2. Carbon dioxide at a temperature of 30°C and a pressure of 18 MPa was stored in the second cylinder 100-2.

[0123] When energy is used, the temperature of the second cylinder 100-2, the fourth cylinder 100-4, the fifth cylinder 100-5, and the seventh cylinder 100-7 is maintained at 30°C, and the temperature of the third cylinder 100-3 is maintained at 60°C. The second piston 120-2 is moved to transfer carbon dioxide from the second cylinder 100-2 to the seventh cylinder 100-7, and 2.47 kg of gaseous carbon dioxide is sealed in the seventh cylinder 100-7.

[0124] In the seventh cylinder 100-7, the seventh piston 120-7 moved downward, outputting 46 kJ of energy. The pressure of the carbon dioxide decreased to 7 MPa. The temperature of the carbon dioxide was then adjusted to 30°C by the seventh cylinder temperature regulator 140-7.

[0125] The seventh piston 120-7 was moved to transfer carbon dioxide from the seventh cylinder 100-7 to the third cylinder 100-3. In the third cylinder 100-3, the third piston moved downward, outputting 214 kJ of energy. The pressure of the carbon dioxide decreased to 3 MPa. The temperature of the carbon dioxide was maintained at 60°C by the third cylinder temperature controller 140-3. In the third cylinder temperature controller 140-3, 494 kJ of thermal energy at 60°C, which had been exhausted by the first cylinder temperature controller 140-1 and stored in the heat storage tank, and 19 kJ of thermal energy at 60°C, which had been supplied by the heat pump, were utilized.

[0126] The third piston 120-3 was moved to transfer carbon dioxide from the third cylinder 100-3 to the fifth cylinder 100-5. In the fifth cylinder 100-5, the temperature of the carbon dioxide dropped to 30°C and the pressure dropped to 2.8 MPa. Therefore, while maintaining the temperature at 30°C with the fifth cylinder temperature regulator 140-5, the fifth piston 120-5 was moved upward, inputting 14 kJ of energy to set the pressure of the carbon dioxide to 3 MPa, the same as in the fourth cylinder 100-4.

[0127] When storing energy, 94 kJ of energy was input through the first piston 100-1, 165 kJ of energy through the second piston 100-2, and 7 kJ of energy through the third piston 100-3. When using energy, 46 kJ of energy was output through the seventh piston 100-7, 19 kJ of energy was input by the heat pump, 214 kJ of energy was output by the third piston 100-3, and 14 kJ of energy was input through the fifth piston 100-5. As a result, with an input of 266 kJ (= 94 kJ + 165 kJ + 7 kJ), the output of 227 kJ (= 46 kJ - 19 kJ + 214 kJ - 14 kJ) was obtained, resulting in an energy storage efficiency of approximately 85% (= 227 kJ ÷ 266 kJ × 100).

[0128] <Third Embodiment> <<Configuration>> The configuration of the energy storage device 30 according to the third embodiment of the present invention will now be described. Figure 48 is a schematic diagram of the energy storage device 30 according to the third embodiment of the present invention. As shown in Figure 48, the energy storage device 30 comprises a first cylinder 100-1, a second cylinder 100-2, a third cylinder 100-3, piping 200, and a control unit 300 (not shown). The first cylinder 100-1, the second cylinder 100-2, and the third cylinder 100-3 have the same configuration as the cylinder 100 described above. The maximum volume of the third cylinder 100-3 is greater than the maximum volumes of the first cylinder 100-1 and the second cylinder 100-2. Furthermore, if the total maximum volume of the third cylinder 100-3 is greater than the total maximum volume of the first cylinder 100-1 and the second cylinder 100-2, the first cylinder 100-1, the second cylinder 100-2, and the third cylinder 100-3 may be configured by connecting multiple cylinders 100 in parallel, as shown in Figure 4, to increase the maximum volume. The third space S3 of the third cylinder 100-3 is filled with the medium 130.

[0129] The first cylinder 100-1 has a first cylinder temperature regulator 140-1. The second cylinder 100-2 has a second cylinder temperature regulator 140-2. The third cylinder 100-3 has a third cylinder temperature regulator 140-3.

[0130] (Piping) Piping 200 includes a first pipe 200-1, a second pipe 200-2, and a third pipe 200-3. Inside the first pipe 200-1, one end leads to the first space S1 in the first cylinder 100-1, and the other end leads to the second space S2 in the second cylinder 100-2. The first pipe 200-1 connects the first space S1 and the second space S2. Inside the second pipe 200-2, one end leads to the second space S2, and the other end leads to the third space S3 in the third cylinder 100-3. The second pipe 200-2 connects the second space S2 and the third space S3. The interior of the third pipe 200-3 is connected on one end to the third space S3 and on the other end to the first space S1 in the first cylinder 100-1. The third pipe 200-3 connects the third space S3 and the first space S1. Examples of materials for the first pipe 200-1, the second pipe 200-2, and the third pipe 200-3 include those similar to those of the cylinder 100 described above.

[0131] The piping 200 has a first-first valve 220-1-1, a first-second valve 220-1-2, a first-third valve 220-1-3, a second valve 220-2, a third-first valve 220-3-1, and a third-second valve 220-3-2. The first-first valve 220-1-1, the first-second valve 220-1-2, and the first-third valve 220-1-3 are arranged in the first piping 200-1 in order from the first cylinder 100-1 side, and open and close the inside of the first piping 200-1 to adjust the movement of the medium 130 inside the first piping 200-1. The second valve 220-2 is located in the second pipe 200-2 and opens and closes the inside of the second pipe 200-2 to adjust the movement of the medium 130 inside the second pipe 200-2. The third-first valve 220-3-1 and the third-second valve 220-3-2 are located in the third pipe 200-3 in order from the third cylinder 100-3 side and open and close the inside of the third pipe 200-3 to adjust the movement of the medium 130 inside the third pipe 200-3. The material of the first-first valve 220-1-1, the first-second valve 220-1-2, the first-third valve 220-1-3, the second valve 220-2, the third-first valve 220-3-1, and the third-second valve 220-3-2 can be, for example, the same as that of the cylinder 100 described above. Valves 220-1-1 (1st-1), 220-1-2 (1st-2nd), 220-1-3 (1st-3rd), 220-2 (2nd), 220-3-1 (3rd-1st), and 220-3-2 (3rd-2nd) are connected to a valve drive unit 330 and driven by the valve drive unit 330. Valves 220-1-1 (1st-1st), 220-1-2 (1st-2nd), 220-1-3 (1st-3rd), 220-2 (2nd), 220-3-1 (3rd-1st), and 220-3-2 (3rd-2nd) are used to restrict or release the movement of the medium 130, or to adjust the flow rate of the medium 130, by opening and closing them.Furthermore, by restricting or releasing the movement of the first piston 120-1, the second piston 120-2, and the third piston 120-3, the movement of the medium 130 can be restricted or released, and in some cases, the same functions as the first-first valve 220-1-1, the first-second valve 220-1-2, the first-third valve 220-1-3, the second valve 220-2, the third-first valve 220-3-1, and the third-second valve 220-3-2 can be omitted.

[0132] The piping 200 includes a first-first piping temperature regulator 230-1-1, a first-second piping temperature regulator 230-1-2, and a third piping temperature regulator 230-3. The first-first piping temperature regulator 230-1-1 is located between the first-first valve 220-1-1 and the first-second valve 220-1-2 and is positioned within a portion of the first piping 200-1. The first-second piping temperature regulator 230-1-2 is located between the first-second valve 220-1-2 and the first-third valve 220-1-3 and is positioned within a portion of the first piping 200-1. The first-first piping temperature regulator 230-1-1 and the first-second piping temperature regulator 230-1-2 each regulate the temperature of the medium 130 inside the first piping 200-1. There is no limit to the number of pipe temperature controllers that can be placed in the first pipe 200-1. By having multiple controllers, the medium 130 can be cooled in the temperature range between the temperature of the first cylinder 100-1 and the temperature of the second cylinder 100-2, and the thermal energy to the desired temperature can be discharged in stages and effectively utilized as thermal energy. The third pipe temperature controller 230-3 is located between the third-first valve 220-3-1 and the third-second valve 220-3-2, and is placed in a part of the third pipe 200-3. The third-first pipe temperature controller 230-3-1 adjusts the temperature of the medium 130 inside the third pipe 200-3. There is no limit to the number of pipe temperature controllers that can be placed in the third pipe 200-3. By having multiple controllers, the medium 130 can be heated in stages in the temperature range between the temperature of the third cylinder 100-3 and the temperature of the first cylinder 100-1. The number of pipe temperature controllers located in the third pipe 200-3 may be the same as the number of pipe temperature controllers located in the first pipe 200-1. In the pipe temperature controllers located in the third pipe 200-3, the heat energy discharged from the pipe temperature controllers located in the first pipe 200-1 can be used to heat the medium 130. Examples of the first-first pipe temperature controller 230-1-1, the first-second pipe temperature controller 230-1-2, and the third pipe temperature controller 230-3 include heat exchangers and heat pumps.The first-1 pipe temperature controller 230-1-1, the first-2 pipe temperature controller 230-1-2, and the third pipe temperature controller 230-3 are connected to the pipe temperature control unit 340 and controlled by the pipe temperature control unit 340.

[0133] (Control Unit) As shown in Figure 14, the control unit 300 is communicatively connected to the piston drive unit 310, the cylinder temperature control unit 320, the valve drive unit 330, and the piping temperature control unit 340. Based on a pre-stored program, the control unit 300 controls the piston drive unit 310, the valve drive unit 330, the cylinder temperature control unit 320, and the piping temperature control unit 340 according to the user's input.

[0134] <<Operation>> The operation of the energy storage device 30 according to the third embodiment of the present invention will be described. Furthermore, the first piston 120-1, the second piston 120-2, and the third piston 120-3 are driven via the piston drive unit 310, the first valve 220-1-1, the first valve 220-1-2, the first valve 220-1-3, the second valve 220-2, the third valve 220-3-1, and the third valve 220-3-2 are driven via the valve drive unit 330, the first cylinder temperature regulator 140-1, the second cylinder temperature regulator 140-2, and the third cylinder temperature regulator 140-3 are controlled via the cylinder temperature control unit 320, and the first pipe temperature regulator 230-1-1, the first pipe temperature regulator 230-1-2, and the third pipe temperature regulator 230-3 are controlled via the pipe temperature control unit 340, all of which are controlled by the control unit 300.

[0135] The third cylinder 100-3 is maintained at a third pressure P3. The third pressure P3 is set, for example, between 1 MPa and 100 MPa. The temperatures of the third cylinder 100-3 and the second cylinder 100-2 are set to a third temperature T3 and a second temperature T2, respectively, by the third cylinder temperature controller 140-3 and the second cylinder temperature controller 140-2. The third temperature T3 and the second temperature T2 are set, for example, between -30°C and 200°C. The first cylinder 100-1 is maintained at a first temperature T1 by the first cylinder regulator 140-1. The first temperature T1 is set, for example, between 0°C and 500°C. A portion of the third piping 200-3 is maintained at the third-first temperature T3-1 by the third piping temperature controller 230-3. For example, the temperature T3-1 of the third-first pipe is set to a range of 0°C to 500°C. A portion of the first piping 200-1 is maintained at the temperatures of the first-first pipe temperature regulator T1-1 and the first-second pipe temperature regulator T1-2 by the first-first pipe temperature regulator 230-1-1 and the first-second pipe temperature regulator 230-1-2, respectively. For example, the temperature T1-1 of the first-first pipe is set to a range of 50°C to 500°C. For example, the temperature T1-2 of the first-second pipe is set to a range of -30°C to 400°C.

[0136] The restriction on the movement of the first piston 120-1 is released while maintaining the pressure so that the first piston 120-1 can move. The valve 1-1 220-1-1 is closed. In this state, the opening and closing amounts of the valve 3-1 220-3-1 and the valve 3-2 220-3-2 are adjusted so that the third piston 120-3 is moved upward while maintaining the pressure of the medium 130, so that the volume of the third space S3 decreases, as shown in Figure 49. As a result, the medium 130 moves from the third space S3 to the first space S1 via the third pipe 200-3. The medium 130 is heated by the third pipe temperature controller 230-3 until its temperature reaches the third-first temperature T3-1. By adjusting the opening and closing amounts of the third-first valve 220-3-1 and the third-second valve 220-3-2, the flow rate of the medium 130 in the third pipe 200-3 can be adjusted, thereby heating the medium 130 to a desired temperature in the third pipe temperature controller 230-3. The third pipe temperature controller 230-3 can utilize the thermal energy discharged from the first-first pipe temperature controller 230-1-1 and the first-second pipe temperature controller 230-1-2. In the first cylinder 100-1, the first piston 100-1 moves downward so that the volume of the first space S1 increases due to the movement of the medium 130.

[0137] Once a predetermined amount of medium 130 has moved into the first space S1 of the first cylinder 100-1, the third-second valve 220-3-2 is closed. The medium 130 is heated in the first cylinder 100-1 by the first cylinder temperature controller 140-1 until its temperature reaches T1. In this state, as shown in Figure 50, the first piston 100-1 is moved upward so that the volume of the first space S1 decreases. The pressure of the medium 130 in the first space S1 is set to a first pressure P1. The first pressure P1 is set, for example, between 1 MPa and 100 MPa. Although the temperature of the medium 130 in the first space S1 tends to rise due to the decrease in the volume of the first space S1, it is maintained at the first temperature T1 by the first cylinder temperature controller 140-1. In the first cylinder temperature regulator 140-1, thermal energy at the first temperature T1 is discharged. The discharged thermal energy at the first temperature T1 can be effectively utilized.

[0138] The restriction on the movement of the second piston 120-2 is released while maintaining the pressure. The second valve 220-2 is closed. In this state, the opening and closing amounts of the first-first valve 220-1-1, the first-second valve 220-1-2, and the first-third valve 220-1-3 are adjusted so that, as shown in Figure 51, the pressure of the medium 130 in the first space S1 is maintained at the first pressure P1, and the first piston 120 is moved upward. As a result, the medium 130 moves from the first space S1 to the second space S2 via the first pipe 200-1. The medium 130 is cooled by the first-first pipe temperature controller 230-1-1 until its temperature reaches the first-first temperature T1-1, and then cooled by the first-second pipe temperature controller 230-1-2 until its temperature reaches the first-second temperature T1-2. By adjusting the opening and closing amounts of the first-first valve 220-1-1, the first-second valve 220-1-2, and the first-third valve 220-1-3, the flow rate of the medium 130 in the first pipe 200-1 can be adjusted, thereby cooling the medium 130 to a desired temperature in the first-second pipe temperature controllers 230-1-2. The thermal energy dissipated by the first-first pipe temperature controllers 230-1-1 and the first-second pipe temperature controllers 230-1-2 can be utilized in the third pipe temperature controller 230-3.

[0139] Once a predetermined amount of medium 130 has moved into the second space S2, the first to third valves 220-1-3 are closed, releasing the pressure maintenance of the second piston 120-2. In the second cylinder 100-2, the medium 130 moves the second piston 120-2 downward so that the volume of the second space S2 increases. The movement of the third piston 120-3 can be used as energy. Although the temperature of the medium 130 in the second space S2 tends to decrease due to the increase in volume of the second space S2, the second cylinder temperature regulator 140-2 keeps the temperature of the medium 130 at the second temperature T2. As a result, the pressure of the medium 130 can be set to the same third pressure P3 as in the third cylinder 100-3. The third pressure P3 is set, for example, between 0.1 MPa and 80 MPa. The second cylinder temperature controller 140-2 can utilize the thermal energy discharged by the first and second piping temperature controllers 230-1-2. The second cylinder 100-2 (and the second piping 200-2) is for setting the pressure of the medium 130 to the same pressure as the third cylinder 100-3, and can be omitted if the pressure or output of the other cylinders 100 can be adjusted. In this case, the first piping 200-1 connects the first space S1 and the third space S3, and the medium 130 moves from the first space S1 to the third space S3 via the first piping 200-1. The third cylinder 100-3 and the first cylinder 100-1 may also be read as the first cylinder 100-1 and the second cylinder 100-2, respectively.

[0140] When recovering the medium 130 into the third cylinder 100-3, the restriction on the movement of the third piston 120-3 is released while maintaining the pressure. The third valve 220-3 is closed and the second valve 220-2 is opened. In this state, as shown in Figure 52, the second piston 120-2 is moved upward while maintaining the pressure of the medium 130. As a result, the medium 130 moves from the second space S2 to the third space S3 via the second piping 200-2.

[0141] <<Example>> Carbon dioxide at a temperature of 30°C and a pressure of 3 MPa was sealed in the third cylinder 100-3. The third piston 120-3 was moved to transfer carbon dioxide from the third cylinder 100-3 to the first cylinder 100-1 via the third pipe 200-3, sealing 2.47 kg of gaseous carbon dioxide into the first cylinder 100-1. The carbon dioxide in the third pipe 200-3 was heated to a temperature of 100°C by the third pipe temperature controller 230-3. In the first cylinder 100-1, the carbon dioxide was heated to a temperature of 160°C, and the first piston 120-1 was moved upward to input 458 kJ of energy. The pressure of the carbon dioxide rose to 60 MPa. In the first cylinder temperature controller 140-1, a temperature of 160°C and 744 kJ of thermal energy were discharged.

[0142] In the first pipe 200-1, the carbon dioxide was cooled to 120°C by the first-1 pipe temperature controller 230-1-1, and then its temperature was reduced to 30°C by the first-2 pipe temperature controller 230-1-2. The 234 kJ of thermal energy above 120°C discharged in the first-1 pipe temperature controller 230-1-1 was utilized in the third pipe temperature controller 230-3. The 188 kJ of thermal energy above 80°C discharged in the first-2 pipe temperature controller 230-1-2 was utilized in the third pipe temperature controller 230-3, and the 164 kJ of thermal energy between 30°C and 80°C discharged in the first-2 pipe temperature controller 230-1-2 was utilized in the second cylinder temperature controller 140-2.

[0143] Due to the movement of carbon dioxide, the second piston 120-2 in the second cylinder 100-2 moved downward, outputting 239 kJ of energy.

[0144] The movement of the first piston 100-1 input 458 kJ of energy. The movement of the second piston 100-2 output 239 kJ of energy. The first piston 100-1 then discharged 744 kJ of thermal energy at a temperature of 160°C. Therefore, the input / output difference between the first piston 100-1 and the second piston 100-2 was 219 kJ (= 458 kJ - 239 kJ), and the output of 744 kJ of thermal energy at a temperature of 160°C was equal to the input / output difference of 219 kJ (= 458 kJ - 239 kJ).

[0145] Although this embodiment has been described above, any other effects and advantages brought about by the aspects described in this embodiment that are obvious from this specification or that can be appropriately conceived by those skilled in the art are naturally considered to be brought about by the present invention.

[0146] 10, 20, 30 Energy storage device 100 Cylinder 110 Cylinder 120 Piston 130 Medium 140 Cylinder temperature regulator 200 Piping 210 Branch 220 Valve 230 Piping temperature regulator 300 Control unit

Claims

1. A first cylinder having a first cylinder, a gas sealed in a first space partitioned inside the first cylinder, and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder, a liquid sealed in a second space partitioned inside the second cylinder, and a second cylinder temperature regulator for adjusting the temperature; a third cylinder having a third cylinder and a third cylinder temperature regulator for adjusting the temperature; a first pipe having one end leading to the first space, a second pipe having one end leading to the second space, a third pipe having one end leading to a third space partitioned inside the third cylinder, a branch section leading to the other of the first pipe, the second pipe, and the third pipe, a second pipe temperature regulator for adjusting the temperature of a part of the second pipe, and a third pipe temperature regulator for adjusting the temperature of a part of the third pipe; The system includes a control unit that changes the volume of the first space, the second space, and the third space, and controls the first cylinder temperature regulator, the second cylinder temperature regulator, the third cylinder temperature regulator, and the second pipe temperature regulator and the third pipe temperature regulator, wherein when storing energy, the control unit controls the first cylinder temperature regulator and the second cylinder temperature regulator so that the temperature of the first cylinder is higher than the temperature of the second cylinder, the control unit reduces the volume of the first space so that the gas moves from the first space to the first pipe, the branch section, and the second pipe, the control unit controls the second pipe temperature regulator so that the temperature of the gas is the temperature of the second cylinder, the gas moves through the second pipe to the second space and dissolves in the liquid,When using the stored energy, the control unit controls the first cylinder temperature regulator, the second cylinder temperature regulator and the third cylinder temperature regulator so that the temperature of the first cylinder is higher than the temperatures of the second cylinder and the third cylinder; the control unit reduces the volume of the second space so that the liquid moves from the second space to the second pipe; the control unit controls the second pipe temperature regulator so that the temperature of the liquid is the temperature of the first cylinder; the gas emitted from the liquid moves to the first space through the second pipe, the branch and the first pipe; the liquid from which the gas has been emitted moves to the second pipe, the branch and the third pipe; the control unit controls the third pipe temperature controller so that the temperature of the liquid is the temperature of the third cylinder; and the liquid moves to the third space through the third pipe.

2. The energy storage device according to claim 1, wherein the second pipe temperature regulator includes, in order from the branching section, a second-first pipe temperature regulator and a second-second pipe temperature regulator, and the third pipe temperature regulator includes, in order from the branching section, a third-first pipe temperature regulator and a third-second pipe temperature regulator.

3. The energy storage system according to claim 2, wherein thermal energy is exchanged between the piping temperature controller 2-1 and the piping temperature controller 3-1, and thermal energy is exchanged between the piping temperature controller 2-2 and the piping temperature controller 3-2.

4. The energy storage device according to claim 3, wherein the gas is carbon dioxide and the liquid is water.

5. A first cylinder having a first cylinder, a second cylinder having a second cylinder, a third cylinder having a third cylinder, piping having a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder, and a second pipe connecting the second space and a third space partitioned inside the third cylinder, a medium sealed in the first space and moving through the first pipe and the second pipe to the first space, the second space and the third space, and a control unit that changes the volume of the first space and the volume of the second space, wherein the maximum volumes of the first cylinder and the third cylinder are greater than the maximum volume of the second cylinder. An energy storage device wherein, when storing energy, the control unit reduces the volume of the first space so that the medium sealed in the first space moves to the second space through the first pipe, the control unit reduces the volume of the second space so that the medium is pressurized, the control unit reduces the volume of the second space so that the medium moves from the second space to the third space through the second pipe, and when using the stored energy, the control unit reduces the volume of the third space so that the medium moves from the third space to the second space through the second pipe, and the volume of the second space is increased.

6. A first cylinder having a first cylinder, a second cylinder having a second cylinder, a third cylinder having a third cylinder, a fourth cylinder having a fourth cylinder, a piping having a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder, a second pipe connecting the second space and a third space partitioned inside the third cylinder, a third pipe connecting the third space and a fourth space partitioned inside the fourth cylinder, and a fourth pipe connecting the fourth space and the first space, and a medium sealed in the fourth space that moves through the fourth pipe, the first pipe, the second pipe and the third pipe to the fourth space, the first space, the second space and the third space, An energy storage device comprising: a control unit for changing the volume of the first space, the volume of the second space, the volume of the third space, and the volume of the fourth space, wherein the maximum volumes of the second and fourth cylinders are greater than the maximum volumes of the first and third cylinders, when storing energy, the control unit reduces the volume of the fourth space so that the medium sealed in the fourth space moves to the first space through the fourth pipe, the control unit pressurizes the medium by reducing the volume of the first space, the control unit moves the medium from the first space to the second space through the first pipe by reducing the volume of the first space, and when using the stored energy, the control unit reduces the volume of the second space so that the medium moves from the second space to the third space through the second pipe and increases the volume of the third space.

7. The energy storage device according to claim 6, wherein the medium is carbon dioxide.

8. A first cylinder having a first cylinder and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder; a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder; a second pipe connecting the second space and the first space; a first pipe temperature regulator for adjusting the temperature of a part of the first pipe; a second pipe temperature regulator for adjusting the temperature of a part of the second pipe; a medium sealed in the first space and moving between the first space and the second space through the first pipe and the second pipe; a control unit that changes the volume of the first space and the volume of the second space and controls the first pipe temperature regulator and the second pipe temperature regulator, wherein the maximum volume of the first cylinder is greater than the maximum volume of the second cylinder. An energy storage device comprising: a control unit that controls a second cylinder temperature controller so that the temperature of the second cylinder is higher than the temperature of the first cylinder; a control unit that reduces the volume of the first space so that the medium moves from the first space to the first piping, the medium is heated in the first piping temperature controller, the medium moves through the first piping to the second space; a control unit that reduces the volume of the second space so that the medium is pressurized and thermal energy is released; a control unit that reduces the volume of the second space so that the medium moves from the second space to the second piping, the medium is cooled in the second piping temperature controller, and the medium moves through the second piping to the first space.

9. The energy storage device according to claim 8, wherein the thermal energy discharged when the medium is cooled in the second pipe temperature controller is used when the medium is heated in the first pipe temperature controller.

10. A first cylinder having a first cylinder and a first cylinder temperature regulator for adjusting the temperature; a second cylinder having a second cylinder; a third cylinder having a third cylinder; a first pipe connecting a first space partitioned inside the first cylinder and a second space partitioned inside the second cylinder; a second pipe connecting the second space and a third space partitioned inside the third cylinder; a third pipe connecting the third space and the first space; a first pipe temperature regulator for adjusting the temperature of a part of the first pipe; a third pipe temperature regulator for adjusting the temperature of a part of the third pipe; a medium sealed in the third space and moving through the third pipe, the first pipe and the second pipe to the third space, the first space and the second space; An energy storage device comprising: a control unit that changes the volume of the first space, the volume of the second space, and the volume of the third space, and controls the first pipe temperature controller and the third pipe temperature controller, wherein the maximum volume of the third cylinder is greater than the maximum volume of the first cylinder, the control unit controls the first cylinder temperature controller so that the temperature of the first cylinder is higher than the temperature of the third cylinder, the control unit reduces the volume of the third space so that the medium moves from the third space to the third pipe, the medium is heated in the third pipe temperature controller, the medium moves through the third pipe to the first space, the control unit reduces the volume of the first space so that the medium is pressurized and thermal energy is released, the control unit reduces the volume of the first space so that the medium moves from the first space to the first pipe, the medium is cooled in the first pipe temperature controller, and the medium moves through the first pipe to the second space.

11. The energy storage device according to claim 10, wherein the thermal energy discharged when the medium is cooled in the first pipe temperature controller is used when the medium is heated in the third pipe temperature controller.

12. An energy storage system comprising an energy storage device according to any one of claims 1 to 11 and a generator connected to the energy storage device.

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