Carnot cell and energy storage system

Abstract

A Carnot cell (10) is provided with: a heat source device (11) that converts electric power into heat and generates high-temperature air; a high-temperature heat storage body (12) provided downstream of the heat source machine (11), the high-temperature heat storage body including a latent heat storage material that receives high-temperature air supplied from the heat source machine (11), stores heat, and releases the heat; and a steam power generation facility (13) that is provided downstream of the high-temperature heat storage body (12), recovers heat from the high-temperature air supplied from the high-temperature heat storage body (12), and converts the heat into electric power. The high-temperature heat storage body (12) may be provided with a covering member that covers a latent heat storage material, and the latent heat storage material accumulates and releases heat in a molten state within the covering member.

Description

Technical Field

[0001] The invention relates to a Carnot battery and an energy storage system. Background Art

[0002] In recent years, energy storage technology has attracted much attention in order to balance the power of the system including power from renewable energy sources with large output fluctuations. As energy storage technologies, methods such as hydroelectric power generation, lithium-ion batteries, compressed air energy storage (CAES), and hydrogen energy storage are known, but they have problems in terms of site selection requirements, costs, and storage periods, so the development of new energy storage technologies is being promoted. As one of the new energy storage technologies, the Carnot battery that stores energy through heat has attracted much attention. For example, Patent Document 1 discloses a Carnot battery that uses the sensible heat of solid particles such as concrete, gravel, and rock to pre-store heat, and uses the stored heat to generate electricity.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application No. 2022-502623 Summary of the invention

[0006] Problems to be solved by the invention

[0007] In the Carnot battery of Patent Document 1, sensible heat is used in the heat storage of solid particles, so in order to keep the air supplied to the turbine at a high temperature, a large amount of heated solid particles need to be stored in a silo in advance. Therefore, in the Carnot battery of Patent Document 1, heat is stored in solid particles in advance by a heater during a time period when the power demand is small and the solid particles are stored in a silo, and in another time period when the power demand is large, the stored solid particles are moved to a heat exchanger and generate electricity. In this way, in the Carnot battery of Patent Document 1, it is impossible to stably supply power to the outside, and there is room for improvement.

[0008] The present invention has been made based on such a background, and an object of the present invention is to provide a Carnot battery and an energy storage system that can stably supply electric power that absorbs output fluctuations from renewable energy.

[0009] Solutions for solving problems

[0010] In order to achieve the above object, the Carnot battery of the present invention has:

[0011] a first conversion unit that converts the electricity into heat and generates high-temperature air;

[0012] a high-temperature heat storage body provided at a downstream side of the first conversion unit, the high-temperature heat storage body including a latent heat storage material that receives the high-temperature air supplied from the first conversion unit to store heat and releases the heat; and

[0013] The second conversion unit is provided on the downstream side of the high-temperature heat storage body, recovers heat from the high-temperature air supplied from the high-temperature heat storage body, and converts the heat into electric power.

[0014] Effects of the Invention

[0015] According to the present invention, it is possible to provide a Carnot battery and an energy storage system that can stably supply electric power that absorbs output fluctuations from renewable energy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a diagram showing the configuration of an energy storage system according to an embodiment of the present invention.

[0017] Figure 2 It is a diagram showing the structure of a Carnot battery according to an embodiment of the present invention.

[0018] Figure 3 It is a cross-sectional view showing the structure of the electric heater and the high-temperature heat storage body according to the embodiment of the present invention.

[0019] Figure 4A This is a partially enlarged front view of a high-temperature heat storage body according to an embodiment of the present invention.

[0020] Figure 4B Cut along line A-A Figure 4A A cross-sectional view of a high-temperature heat storage body.

[0021] Figure 5 It is a cross-sectional view showing the structure of a low-temperature heat storage body according to an embodiment of the present invention.

[0022] Figure 6 It is a diagram showing a cycle of phase change in the latent heat storage material according to the embodiment of the present invention.

[0023] Figure 7 It is a schematic diagram showing the configuration of a heat supply system according to an embodiment of the present invention.

[0024] Figure 8 It is a cross-sectional view showing the structure of a melter according to an embodiment of the present invention.

[0025] Fig. 9 It is a cross-sectional view showing the structure of the heat recovery device according to the embodiment of the present invention.

[0026] Fig.10 This is a flowchart showing the flow of the heat supply method according to the embodiment of the present invention.

[0027] Fig.11 It is a cross-sectional view showing the structure of a low-temperature heat storage body according to a modified example of the present invention. DETAILED DESCRIPTION

[0028] Hereinafter, the Carnot battery and energy storage system according to the embodiments of the present invention will be described in detail with reference to the accompanying drawings. In each of the drawings, the same or equivalent parts are marked with the same reference numerals.

[0029] The energy storage system of the embodiment is a system that uses a high-temperature heat storage material to convert system power with large output fluctuations into stable generated power with small output fluctuations, and uses a low-temperature heat storage material to recover the heat generated when the system power is converted into generated power and supply heat to the heat demand area. In the heat supply, hot water is supplied to users through pipes, and the users use the hot water for purposes such as hot water supply, heating, and snow melting.

[0030] Both high-temperature heat storage materials and low-temperature heat storage materials are latent heat storage materials (Phase Change Material (PCM)) that use latent heat to store heat. Latent heat storage materials use the latent heat accompanying the phase change between liquid and solid to absorb or release heat, and therefore have a higher heat storage density than sensible heat storage materials. The melting point of the high-temperature heat storage material is, for example, in the range of 500°C to 700°C, and the high-temperature heat storage material releases high-temperature air in the range of 500°C to 700°C. In addition, the melting point of the low-temperature heat storage material is lower than the melting point of the high-temperature heat storage material, for example, in the range of 100°C to 200°C. When releasing heat, the low-temperature heat storage material supplies hot water in the range of 70°C to 80°C, for example.

[0031] System power is the power supplied from the system power supply, and may also include variable power from renewable energy. Power from renewable energy, for example, is power obtained through wind power generation, solar power generation, and tidal power generation, and has the characteristic that the amount of power generated is affected by external conditions such as weather, season, and time period. In the following, it is assumed that the system power includes variable power from renewable energy, resulting in short-cycle fluctuations. Short-cycle fluctuations are fluctuations in the amount of electricity with a period of less than 20 minutes.

[0032] like Figure 1 As shown, the energy storage system 1 includes: a Carnot battery 10 that converts system power with large output fluctuations into stable generated power with small output fluctuations; and a heat supply system 20 that recovers heat discharged from the Carnot battery 10 and supplies heat to a heat demand area. The heat supply system 20 recovers heat contained in exhaust gas generated when the Carnot battery 10 converts heat into electricity.

[0033] The Carnot battery 10 includes a heat source machine 11 that converts system power into heat, a high-temperature heat storage body 12 that stores and releases the heat generated by the heat source machine 11, and a steam power generation device 13 that generates power by generating steam from the heat released from the high-temperature heat storage body 12. The heat source machine 11 is an example of a first conversion unit that converts power into heat and generates high-temperature air, and the steam power generation device 13 is an example of a second conversion unit that recovers heat from the high-temperature air supplied from the high-temperature heat storage body and converts the heat into power.

[0034] The heat supply system 20 includes: a low-temperature heat storage body 21, which is configured to be detachable relative to the steam power generation equipment 13, and the low-temperature heat storage body 21 recovers and stores the heat discharged from the steam power generation equipment 13; and a heat release recovery device 22, which is configured to be able to be attached to the low-temperature heat storage body 21, and the heat release recovery device 22 recovers the heat released from the low-temperature heat storage body 21 and supplies heat to the heat demand area. The heat supply system 20 can also use multiple low-temperature heat storage bodies 21 in sequence or simultaneously to recover the heat from the steam power generation equipment 13 and release the heat in the heat release recovery device 22.

[0035] The low-temperature heat storage body 21 is a box body configured to be transported by a transport unit such as a truck. The low-temperature heat storage body 21 is transported to a heat demand area and can supply heat while being set in the heat recovery device 22. As an example, the low-temperature heat storage body 21 can be stored and preserved in advance during the summer when heat storage is easy, and the low-temperature heat storage body 21 can be set in the heat recovery device 22 during the winter when heat demand is high, so that heat released from the low-temperature heat storage body 21 can be used for heat supply.

[0036] Next, each structure of the Carnot battery 10 according to the embodiment will be described.

[0037] like Figure 2 As shown, the heat source device 11 includes: an electric heater 11a that generates heat energy from electricity; and a blower 11b that blows air toward the electric heater 11a to generate high-temperature air. The electric heater 11a includes, for example, a resistance heating element that generates heat energy through the Joule effect. As long as the system power is supplied, the heat source device 11 receives the system power and converts it into heat, and continuously supplies it to the high-temperature heat storage body 12.

[0038] The high temperature heat storage body 12 has a PCM having a large heat capacity and is disposed on the downstream side of the heat source device 11. The high temperature heat storage body 12 receives the high temperature air supplied from the heat source device 11 to store heat, and releases the heat to the surrounding high temperature air as long as the heat is stored. That is, the high temperature heat storage body 12 adjusts the temperature of the high temperature air flowing from the heat source device 11 to be constant as long as the heat is stored.

[0039] The melting point of the PCM of the high-temperature thermal storage body 12 is, for example, 570°C, and the temperature of the high-temperature air released by the high-temperature thermal storage body 12 is, for example, in the range of 570°C to 600°C. When the PCM solidifies, there is a large exothermic reaction, and even if the system power is reduced, it is controlled to a constant amount of heat, thereby maintaining the inertial force. Therefore, it is preferred that in the high-temperature thermal storage body 12, the latent heat storage material is melted inside the covering member to store and release heat.

[0040] like Figure 3 As shown, the heat source device 11 and the high-temperature heat storage body 12 are, for example, arranged in the pipe 14. The high-temperature heat storage body 12 is formed in a manner that a plurality of passages through which air can pass are adjacent to each other and extend in the same direction. The high-temperature air blown by the blower 11b passes through each passage and exchanges heat with the wall surface. The high-temperature heat storage body 12 may be, for example, a honeycomb structure formed by arranging regular hexagonal holes, or a checkered brick structure formed by arranging circular holes.

[0041] like Figure 4A and Figure 4B As shown, the high temperature heat storage body 12 is composed of a plurality of PCM capsules 12A. The PCM capsule 12A is formed of a sphere having a diameter of about 5 mm to 10 mm, for example, and has a core made of a latent heat storage material and a shell covering the core. Considering the melting point of the latent heat storage material, it is preferred that the core is an aluminum alloy, for example, an Al-Si alloy (4000 series) in which silicon is added to aluminum. The Al-Si alloy is, for example, an aluminum alloy in which 12 wt% of silicon is added to aluminum.

[0042] The shell is an example of a covering member covering the latent heat storage material. Preferably, the shell is a ceramic material, such as alumina (Al2O3) obtained by oxidizing an aluminum alloy. The shell of the PCM capsule 12A is formed of a heat-resistant ceramic, thereby preventing the shell from being damaged by heat or external force and causing the molten core to leak out.

[0043] It should be noted that the heating capacity of the heat source device 11 can be set to, for example, about three times the average input power from the system power supply, and the heat storage capacity of the high-temperature heat storage body 12 can be set to, for example, a capacity equivalent to the average input power from the system power used for 12 hours. As an example, when the average input power is set to 5MW, the heating capacity of the heat source device 11 is 5MW×3=15MW, and when the heating efficiency of the heat source device 11 is set to 100%, the heat storage capacity of the high-temperature heat storage body 12 is 5MW×12 hours=60MWh.

[0044] Back to Figure 2The steam power generation equipment 13 includes: a steam boiler 13a that generates steam by high-temperature air from the high-temperature heat storage body 12; a superheater 13b that superheats the steam generated in the steam boiler 13a; a steam turbine 13c that obtains rotational energy from the steam supplied from the superheater 13b; a generator 13d that generates electricity by the rotational energy from the steam turbine 13c; a condenser 13e that condenses the steam exhausted from the steam turbine 13c; and a water supply pump 13f that supplies water condensed in the condenser 13e to the steam boiler 13a. The components of the steam power generation equipment 13 are arranged to be sequentially connected via pipes that can supply steam or water, so that the steam or water circulates in the steam power generation equipment 13.

[0045] The steam boiler 13a introduces high-temperature air from the high-temperature heat storage body 12 to change the water supplied from the water supply pump 13f into saturated steam. The steam boiler 13a includes: a drum that stores water supplied from the water supply pump 13f; and a plurality of pipes that are arranged in the drum and allow the heated air from the high-temperature heat storage body 12 to pass through, thereby heating the water inside the drum to generate steam. The steam boiler 13a receives high-temperature air in the range of 570°C to 600°C from the high-temperature heat storage body 12, for example, and discharges air at 180°C as exhaust gas. The exhaust gas is used for heat storage by the low-temperature heat storage body 21.

[0046] The superheater 13 b heats the saturated steam generated in the steam boiler 13 a using high-temperature air from the high-temperature heat storage body 12 to convert the saturated steam into superheated steam.

[0047] The steam turbine 13c converts the thermal energy of the superheated steam into rotational energy via the impeller and the rotation shaft. The rotation shaft of the steam turbine 13c is connected to the rotation shaft of the generator 13d, so that the rotation shaft of the generator 13d rotates around its axis.

[0048] The generator 13d converts the rotational energy of the steam turbine 13c into electrical energy. When the power generated by the generator 13d is set to 1 MW, the steam turbine efficiency is about 25%.

[0049] The condenser 13e cools and condenses the wet steam exhausted from the steam turbine 13c, and reduces the exhaust pressure of the steam turbine 13c. A number of cooling pipes are arranged in the tank of the condenser 13e, and the wet steam in the tank can be condensed by passing cooling water through the inside of these cooling pipes. At this time, the cooling water passing through the cooling pipes is changed into hot water, so the hot water can be used to supply heat to nearby locations.

[0050] The water supply pump 13f is a pump that supplies water condensed by the condenser 13e to the steam boiler 13a.

[0051] The above are the components of the Carnot battery 10 .

[0052] Next, each structure of the heat supply system 20 according to the embodiment will be described.

[0053] Back to Figure 1 The low-temperature heat storage body 21 is a movable box body having PCM that melts at a lower temperature than the PCM of the high-temperature heat storage body 12. For example, when the exhaust temperature from the steam boiler 13a is set to 180°C, the melting point of the PCM of the low-temperature heat storage body 21 is preferably in the range of 140°C to 160°C, and more preferably 150°C. The low-temperature heat storage body 21 is changed to a heat storage state by melting the PCM through the exhaust gas from the steam boiler 13a, and can supply heat in a heat demand area, for example, in the range of 70°C to 80°C. In the following, in order to distinguish it from the PCM of the high-temperature heat storage body 12, the PCM of the low-temperature heat storage body 21 is sometimes expressed as "low-temperature PCM".

[0054] like Figure 5 As shown, the low-temperature heat storage body 21 includes: a plurality of PCM capsules 21A; and a container 21B, which is formed to accommodate the PCM capsules 21A inside and can transfer heat between the PCM capsules 21A and the outside. The low-temperature heat storage body 21 stores, moves and releases heat of the PCM capsules 21A in a state where the PCM capsules 21A are accommodated inside the container 21B. The PCM capsule 21A is obtained by enclosing a low-temperature PCM in an alloy capsule, and its particle size is, for example, in the range of 1 mm to 10 mm. The capsule of the PCM capsule 21A is an example of a covering member covering the low-temperature PCM. The container 21B is formed of a heat transfer material such as a metal material. The container 21B can be formed, for example, in a cubic shape so that it can be stacked on each other. In addition. A door that can take out / put in the PCM capsule 21A can also be provided in the container 21B.

[0055] As the low-temperature PCM of the low-temperature heat storage body 21, it is preferable to use the following substances: when cooled from a molten state at a certain speed or more, it undergoes a phase change from a cooled liquid state to a glass state. The supercooled liquid state is a state in which the liquid remains in a liquid state even if the liquid is cooled below the melting point, and the glass state is an amorphous state produced at a temperature lower than the glass transition point. The substance that can phase change to a glass state stores heat when changing from a crystalline state to a molten state, and can maintain the heat storage state by changing to a glass state. In addition, cold crystallization can be caused by temporarily applying heat above the cold crystallization point to the substance in the glass state, thereby releasing latent heat.

[0056] Specifically explain, such as Figure 6As shown, when a substance that will phase change into a glass state is cooled at a certain speed or more from a molten state, it will phase change into a glass state at the glass transition point through a cooling liquid state without releasing the latent heat of crystallization. The substance in the glass state is an amorphous solid, so whether it is low temperature or not, it can be stored in a stable state for a long time while maintaining a state of heat storage. When a part of the substance in the glass state is heated, it will phase change into a supercooled liquid state at the glass transition point, and when further heating is continued, it will phase change into a cold crystallization state at the cold crystallization point. At this time, the latent heat is released to the outside. When the crystal obtained by cold crystallization is heated to above the melting point, it can return to the molten state again. For a substance that will phase change into a glass state in this way, heat storage and heat release can be performed through a cycle such as a molten state, a supercooled liquid state, a glass state, a supercooled liquid state, a cold crystallization, and a crystallization state.

[0057] The substance that changes phase into a glass state is, for example, a polyol, preferably a sugar alcohol. Sugar alcohol is a chain or cyclic polyol obtained by reducing the carbonyl group of a sugar. As the sugar alcohol, it is preferred to use a eutectic formed by two or more sugar alcohols, for example, it is more preferred to use a ternary sugar alcohol formed by three sugar alcohols. An example of a ternary sugar alcohol is a eutectic of mannitol, galactitol and inositol. By adjusting the composition of the eutectic, the melting point, latent heat of fusion, cold crystallization point and latent heat of cold crystallization can be changed.

[0058] The glass transition point of a substance that changes phase into a glass state is preferably within the range of 10°C to 50°C, for example, the melting point (heat storage temperature) is preferably within the range of 100°C to 200°C, and the cold crystallization point (heat release start temperature) is greater than the glass transition point and less than the melting point, for example, preferably within the range of 50°C to 100°C. As an example, the melting point of the eutectic of mannitol, galactitol, and inositol (=0.557 mol: 0.273 mol: 0.206 mol) is 150°C, the glass transition point when the temperature is lowered is 16.1°C, the glass transition point when the temperature is raised is 15.2°C, the cold crystallization point is 72.8°C, the latent heat of melting is 248 kJ / kg, and the latent heat of cold crystallization is 157 kJ / kg. In the eutectic of mannitol, galactitol, and inositol in a glass state, a large amount of latent heat can be released by temporarily applying heat to a part of it to a temperature of about 90°C.

[0059] It should be noted that cooling below -25°C is required to maintain the glass state for about a year, but cooling to the glass state is not necessarily required to maintain the heat storage state of a substance that undergoes a phase transition to the glass state. When the substance is suddenly cooled to a temperature around room temperature (for example, around 40°C), it solidifies into a rubbery state, and the heat storage state can be maintained in this state. If the heat storage state can be maintained at a temperature around room temperature, there is no need to cool the low-temperature heat storage body 21 during storage, and operability is greatly improved.

[0060] like Figure 7 As shown, the heat supply system 20 is provided with a low-temperature thermal storage body 21 and a heat release recovery device 22, and further includes: a melter 23 for melting the low-temperature PCM of the low-temperature thermal storage body 21; a quencher 24 for quenching the low-temperature PCM; a storage warehouse 25 for storing the low-temperature thermal storage body 21; and a truck 26 for transporting the low-temperature thermal storage body 21. In the heat supply system 20, the low-temperature thermal storage body 21 moves in the order of the melter 23, the quencher 24, the storage warehouse 25, the truck 26, and the heat release recovery device 22.

[0061] Taking the low-temperature PCM with a melting point of 150°C, a glass transition point of 16.1°C when cooled, and a cold crystallization point of 72.8°C as an example, the melter 23 melts the low-temperature PCM through the exhaust gas of 180°C from the steam boiler 13a, and discharges the exhaust gas of 140°C into the atmosphere. The quencher 24 changes the low-temperature PCM in a molten state into a glass state as a heat storage state by quenching the low-temperature PCM. After being stored in a glass state and transported to a heat demand area, the heat recovery device 22 temporarily heats a part of the low-temperature PCM in a manner that makes it higher than the cold crystallization point, for example, about 90°C, thereby generating latent heat from the low-temperature PCM, thereby changing the 20°C cold water into hot water in the range of 70°C to 80°C.

[0062] The melter 23 is configured to accommodate the low-temperature heat storage body 21 therein, and melt the low-temperature PCM of the low-temperature heat storage body 21 by the exhaust gas from the steam boiler 13a. Figure 8 As shown, the melter 23 comprises: a shell 23a, which accommodates the low-temperature heat storage body 21 inside; and a pair of heat exchangers 23b, which are arranged in the shell 23a to sandwich the two side surfaces of the low-temperature heat storage body 21, and heat the two side surfaces of the low-temperature heat storage body 21 by heat transfer.

[0063] The front and rear of the shell 23a are open to allow the movement of a trolley 23e carrying the low-temperature heat storage body 21. An intake pipe 23c and an exhaust pipe 23d are connected to each heat exchanger 23b, wherein the intake pipe 23c is connected to the steam boiler 13a and supplies exhaust gas from the steam boiler 13a, and the exhaust pipe 23d discharges the exhaust gas after heat exchange.

[0064] Back to Figure 7 The quencher 24 is configured to accommodate the low-temperature heat storage body 21 inside, and uses the cooling pipe of the condenser 13e to change the molten low-temperature PCM contained in the low-temperature heat storage body 21 into a glass state. The quencher 24 is connected to a heat exchanger in which the cooling pipe of the condenser 13e is configured, and cools the two sides of the low-temperature heat storage body 21 by heat transfer. The quencher 24 has the same or equivalent structure as the melter 23, except that cooling water flows in the heat exchanger.

[0065] The storage warehouse 25 stores the low-temperature heat storage body 21 while maintaining the heat storage state, and the truck 26 transports the low-temperature heat storage body 21 to the heat demand area while maintaining the heat storage state. In order to maintain the heat storage state of the low-temperature heat storage body 21, the temperature of the low-temperature heat storage body 21 can be suppressed below the glass transition point of the low-temperature PCM. It should be noted that when the low-temperature PCM is stored in a state of being cured into a rubber state, the installation of air conditioning equipment in the storage warehouse 25 and the truck 26 can also be omitted.

[0066] The heat recovery device 22 is configured to be able to attach the low-temperature heat storage body 21 inside, and temporarily heat the low-temperature heat storage body 21 to cause cold crystallization of the low-temperature PCM, thereby releasing a large amount of latent heat. Fig. 9 As shown, the heat recovery device 22 includes: a shell 22a, which accommodates the low-temperature heat storage body 21 inside; a heater 22b, which is arranged in the shell 22a and temporarily heats a part of the low-temperature PCM of the low-temperature heat storage body 21 in a manner that the temperature becomes higher than the cold crystallization point; and a heat exchanger 22c, which is arranged in the shell 22a and transfers heat in a state of contact with the low-temperature heat storage body 21, thereby changing cold water supplied from the outside into hot water.

[0067] The housing 22a is provided with a door for taking out / putting in the low-temperature heat storage body 21. In order to accommodate the low-temperature heat storage body 21 in the heat recovery device 22, for example, a container elevator can be used. The heater 22b is arranged in the housing 22a in a manner of contacting the bottom surface and the side surface of the low-temperature heat storage body 21, and the heat exchanger 22c is arranged on the upper side of the housing 22a.

[0068] The above are the components of the heat supply system 20 .

[0069] Next, refer to Fig.10 The flow of the heat supply method according to the embodiment will be described. In the following, it is assumed that the low-temperature PCM of the low-temperature heat storage body 21 provided before the melter 23 is in a crystallized state.

[0070] First, the low-temperature heat storage body 21 is placed in the melter 23, and the low-temperature PCM of the low-temperature heat storage body 21 is changed into a molten state by using the exhaust gas from the steam boiler 13a (step S1). Figure 8 As shown, the low-temperature thermal storage body 21 is placed on a carriage 23e and arranged in a melter 23, and the low-temperature PCM of the low-temperature thermal storage body 21 is melted by a heat exchanger 23b heated by exhaust gas from a steam boiler 13a.

[0071] Next, the low-temperature heat storage body 21 that has been changed to a molten state in step S1 is placed in the quencher 24 and quenched using cooling water from the condenser 13e, thereby changing the low-temperature PCM of the low-temperature heat storage body 21 to a glass state (step S2). Figure 8 When the quencher 24 having the same structure as the shown melter 23 quenches the low-temperature PCM of the low-temperature heat storage body 21 so that the low-temperature PCM becomes below the glass transition point, the low-temperature PCM changes from a cooled liquid state to a glass state.

[0072] Next, the low-temperature heat storage body 21 that has been changed to the heat storage state in the process of step S2 is stored in the storage warehouse 25 (step S3), and the low-temperature heat storage body 21 is transported to the heat demand area using the truck 26 when heat demand is generated (step S4). In the storage warehouse 25 and the truck 26, the heat storage state of the low-temperature PCM can be maintained by maintaining the low-temperature PCM below the glass transition point.

[0073] Next, the low temperature heat storage body 21 is placed in the heat recovery device 22 located in the heat demand area, and heat is released from the low temperature heat storage body 21, thereby supplying heat to the heat demand area (step S5). Fig. 9 As shown in FIG. 1 , when the heater 26b is used to temporarily heat a portion of the low-temperature PCM in a glass state to a temperature above the cold crystallization point, the low-temperature PCM changes from a supercooled liquid state to a crystallized state through a cold crystallization state. At this time, the cold crystallization latent heat is released at the time point when the cold crystallization is performed, so the latent heat can be recovered by the heat exchanger 26c, and the cold water of about 20°C is changed to hot water of about 70 to 80°C.

[0074] Next, the low temperature heat storage body 21 in the crystallized state is returned to the steam power generation equipment 13 (step S6). The low temperature heat storage body 21 after use can be returned to the installation location of the steam power generation equipment 13 using the truck 26. The low temperature heat storage body 21 is set in the melter 23 again in the crystallized state and the same process is repeated, thereby the low temperature heat storage body 21 can be used as a heat source again.

[0075] The above is the flow of the heat supply method.

[0076] As described above, the Carnot battery 10 of the embodiment includes: a heat source machine 11 that converts electric power into heat and generates high-temperature air; a high-temperature heat storage body 12 that is provided on the downstream side of the heat source machine 11, and the high-temperature heat storage body 12 includes a latent heat storage material that receives the high-temperature air supplied from the heat source machine 11 to store heat and release the heat; and a steam power generation device 13 that is provided on the downstream side of the high-temperature heat storage body 12, and the steam power generation device 13 recovers heat from the high-temperature air supplied from the high-temperature heat storage body 12 and converts the heat into electric power. Therefore, the short-cycle fluctuation of the system power including the power from renewable energy can be absorbed by the large heat capacity of the high-temperature heat storage body 12, and as a result, the system power with large output fluctuation can be stably converted into the generated power with small output fluctuation.

[0077] The energy storage system 1 of the embodiment comprises: a Carnot battery 10; a low-temperature heat storage body 21, which is configured to be detachable relative to the steam power generation equipment 13 of the Carnot battery 10, and the low-temperature heat storage body 21 includes a low-temperature PCM that recovers and stores the heat discharged from the steam power generation equipment 13; and a heat release recovery device 22, which is configured to be able to attach the low-temperature heat storage body 21, and the heat release recovery device 22 recovers the heat released from the low-temperature heat storage body 21 and supplies heat to the heat demand area. Therefore, the low-grade heat energy (residual heat) generated in the Carnot battery 10 can be recovered to supply heat in the heat demand area. As a result, the heat utilization rate of the energy storage system 1 can be improved.

[0078] The present invention is not limited to the above-described embodiment, and modifications as described below are possible.

[0079] (Variation Example)

[0080] In the above embodiment, the heat source equipment 11 converts electricity into heat, and the steam power generation equipment 13 converts heat into electricity, but the present invention is not limited thereto. For example, a heat pump may be used to convert electricity into heat or heat into electricity.

[0081] In the above embodiment, in the high temperature heat storage body 12, a plurality of passages through which air can pass are formed adjacent to each other and extend in the same direction, but the present invention is not limited thereto. The high temperature heat storage body 12 may be of any shape as long as it is a structure capable of heat exchange with air, for example, it may be formed into a mesh structure.

[0082] In the above embodiment, the high temperature heat storage body 12 is formed by combining a plurality of spherical PCM capsules 12A, but the present invention is not limited thereto. The PCM capsules 12A may be formed in a block shape or a cylindrical shape, for example.

[0083] In the above embodiment, the particle size of the PCM capsule 12A is formed to be within a range of 1 mm to 10 mm, but the present invention is not limited thereto. For example, the PCM capsule 12A may be formed as fine particles, for example, in a range of 1 μm to 1 mm, and the fine PCM capsule 12A may be placed in a mold and bonded or sintered to form a high-temperature heat storage body 12 of an arbitrary shape.

[0084] In the above embodiment, the exhaust gas from the steam boiler 13a is directly supplied to the melter 23, but the present invention is not limited thereto. For example, a blower for sending the exhaust gas from the steam boiler 13a to the melter 23 may be provided in the middle of the pipe connecting the steam boiler 13a and the melter 23.

[0085] In the above embodiment, the low temperature heat storage body 21 is heat stored by exhaust gas from the steam boiler 13a, but the present invention is not limited thereto. For example, the low temperature heat storage body 21 may be heat stored by extracting gas from the steam turbine 13c.

[0086] In the above embodiment, the container 21B containing many PCM capsules 21A is in a cubic shape, but the present invention is not limited thereto. For example, the container 21B may also be a cylindrical container having an internal space. Fig.11 As shown in FIG. 1 , the container 21B may also include a housing 21a and a pair of partitions 21b, wherein the pair of partitions 21b are arranged inside the housing 21a and accommodate the PCM capsule 21A between the pair of partitions 21b. Through holes 21c through which air can pass are formed at both ends of the housing 21a, and a plurality of through holes 21d through which air can pass are formed in the partition 21b. Therefore, by allowing the exhaust gas from the steam boiler 13a to flow directly from the through holes 21c to the inside of the housing 21a, the PCM capsule 21A can store heat.

[0087] In the above embodiment, the low-temperature thermal storage body 21 includes a plurality of spherical PCM capsules 21A, but the present invention is not limited thereto. The PCM capsules 21A may be formed in a block shape or a cylindrical shape, for example.

[0088] In the above embodiment, many PCM capsules 21A are contained in the container 21B, but the present invention is not limited to this. It is also possible to form a low-temperature heat storage body 21 by connecting many PCM capsules 21A to each other. In addition, in the above embodiment, the particle size of the PCM capsule 21A is in the range of 1 mm to 10 mm, but the present invention is not limited to this. For example, the particle size of the PCM capsule 21A may also be in the range of 1 μm to 1 mm, and such tiny PCM capsules 21A may be connected to form a low-temperature heat storage body 21 of any shape.

[0089] In the above embodiment, PCM that changes phase to glass is used as the low-temperature PCM, but the present invention is not limited thereto. When the low-temperature PCM does not need to be stored for a long time in a heat storage state, PCM that does not change phase to glass may be used as the low-temperature PCM.

[0090] In the above embodiment, the melter 23 and the quencher 24 are configured to heat or cool both sides of the low-temperature heat storage body 21 when the low-temperature heat storage body 21 is placed on the carriage 23e, but the present invention is not limited thereto. For example, the melter 23 may also be configured to heat the low-temperature heat storage body 21 from below by a heat exchanger provided on the bottom surface of the housing 23a. In addition, the quencher 24 may also be configured to cool the low-temperature heat storage body 21 from above by a heat exchanger provided on the upper surface of the housing.

[0091] The above-mentioned embodiments are illustrative, and the present invention is not limited thereto, and various embodiments can be implemented within the scope of the gist of the invention described in the claims. The constituent elements described in the embodiments and modifications can be freely combined. In addition, inventions equivalent to the inventions described in the claims are also included in the present invention.

[0092] Industrial Applicability

[0093] The Carnot battery and energy storage system of the present invention are useful because they can stably supply electric power that absorbs output fluctuations from renewable energy.

[0094] Description of Reference Numerals

[0095] 1: Energy storage system;

[0096] 10: Carnot battery;

[0097] 11: Heat source machine;

[0098] 11b: air blower;

[0099] 12: High temperature heat storage body;

[0100] 12A, 21A: PCM capsule;

[0101] 13: Steam power generation equipment;

[0102] 13a: Steam boiler;

[0103] 13c: Steam turbine;

[0104] 13e: condenser;

[0105] 20: Heat supply system;

[0106] 21: Low temperature heat storage body;

[0107] 21B: container;

[0108] 22: heat recovery device;

[0109] 23: Melter;

[0110] 24: Quench cooler.

Claims

1. A Carnot battery, comprising: a first conversion unit that converts the electricity into heat and generates high-temperature air; a high-temperature heat storage body provided at a downstream side of the first conversion unit, the high-temperature heat storage body including a latent heat storage material that receives the high-temperature air supplied from the first conversion unit to store heat and releases the heat; and The second conversion unit is provided on the downstream side of the high-temperature heat storage body, recovers heat from the high-temperature air supplied from the high-temperature heat storage body, and converts the heat into electric power.

2. The Carnot battery according to claim 1, wherein: The high temperature heat storage body comprises a covering member covering the latent heat storage material, The latent heat storage material stores and releases heat in a molten state inside the covering member.

3. The Carnot battery according to claim 1 or 2, wherein: The first conversion unit includes a blower for blowing high-temperature air toward the high-temperature heat storage body. The high-temperature heat storage body includes a plurality of passages arranged to extend in the same direction and through which the high-temperature air blown from the blower passes.

4. The Carnot battery according to claim 2, wherein: The high temperature heat storage body is formed by combining a plurality of phase change material PCM capsules formed by covering the latent heat storage material with the covering member.

5. An energy storage system comprising: The Carnot battery according to claim 1; a low-temperature heat storage body configured to be detachable relative to the second conversion unit of the Carnot battery, the low-temperature heat storage body including a latent heat storage material that recovers and stores heat discharged from the second conversion unit; and The heat recovery device is configured to be able to be attached to the low-temperature heat storage body, and the heat recovery device recovers the heat released from the low-temperature heat storage body and supplies heat to the heat demand area.

6. The energy storage system according to claim 5, wherein: The low temperature heat storage body comprises: A plurality of PCM capsules, wherein the PCM capsules are formed by encapsulating a latent heat storage material with an encapsulating member; and The container is formed to accommodate a plurality of PCM capsules inside and to enable heat transfer between the PCM capsules and the outside.

7. The energy storage system according to claim 5 or 6, wherein: The second conversion unit is a steam power generation device that generates steam in a steam boiler using the heat released by the low-temperature heat storage body and drives a steam turbine using the steam generated in the steam boiler. The energy storage system includes a melter connected to the steam boiler and configured to melt the latent heat storage material included in the low-temperature heat storage element by exhaust gas from the steam boiler.

8. The energy storage system according to claim 7, wherein: The low-temperature heat storage body contains a latent heat storage material, which changes from a molten state to a glass state through a cooled liquid state when being rapidly cooled at a certain speed or above. The energy storage system includes a quencher connected to a condenser of the steam power generation equipment and causing a molten latent heat storage material included in the low-temperature heat storage body to undergo a phase change into a glass state by using cold water passing through a cooling pipe of the condenser.

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