Carnot Battery and Energy Storage System

Abstract

A Carnot battery (10) comprises: a heat source device (11) that converts electric power into heat so as to generate high-temperature air; a high-temperature heat storage body (12) that is provided downstream of the heat source device (11) and that includes a latent heat storage material which receives the high-temperature air supplied from the heat source device (11) and which stores and releases heat; a steam power plant (13) that is provided downstream of the high-temperature heat storage body (12) and that 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) includes a cover member which covers the latent heat storage material, and the latent heat storage material may store and releases heat in a state in which the latent heat storage material is melted inside the cover member.

Description

[Technical Field]

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

[0002] In recent years, attention has been focused on energy storage technologies in order to level out grid power, including electricity derived from renewable energy sources, which have large output fluctuations. Known energy storage technologies include pumped-storage power generation, lithium-ion batteries, compressed air energy storage (CAES), and hydrogen storage. However, each of these technologies has its own challenges, such as location requirements, cost, and storage period, and therefore new energy storage technologies are being developed. One new energy storage technology that has attracted attention is the Carnot battery, which stores energy as heat. For example, Patent Document 1 discloses a Carnot battery that stores heat by utilizing the sensible heat of solid particles such as concrete, gravel, and rock, and then generates electricity using the stored heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2022-502623 Summary of the Invention [Problem to be solved by the invention]

[0004] The Carnot battery of Patent Document 1 uses sensible heat to store heat in solid particles, so in order to keep the air supplied to the turbine at a high temperature, it is necessary to store a large amount of heated solid particles in a silo. For this reason, the Carnot battery of Patent Document 1 uses a heater to store heat in the solid particles during times of low power demand and stores them in a silo, and then during other times of high power demand, the stored solid particles are moved to a heat exchanger to generate power. As such, the Carnot battery of Patent Document 1 is unable to provide a stable supply of power to the outside world, and there is room for improvement.

[0005] The present invention has been made based on this background, and aims to provide a Carnot battery and energy storage system that can stably supply electric power that absorbs output fluctuations derived from renewable energy. [Means for solving the problem]

[0006] In order to achieve the above object, the Carnot battery according to the present invention comprises: a first conversion means for converting electrical power into heat to generate hot air; the first conversion means than the flow path and the second conversion means is provided downstream of the first conversion means. The aforementioned Hot air Between Accumulates heat Or release Or Contains latent heat storage material and adjusts the temperature of the hot air by contacting the hot air. A high-temperature heat storage body; the high-temperature heat storage body than the flow path and the high-temperature heat storage medium is provided downstream of the The aforementioned a second conversion means for recovering heat from the hot air and converting it into electricity; , and The melting point of the latent heat storage material is in the range of 500°C to 700°C. do. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a Carnot battery and an energy storage system that can stably supply electric power in which output fluctuations derived from renewable energy are absorbed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of an energy storage system according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing the configuration of a Carnot battery according to an embodiment of the present invention; [Figure 3] 1 is a cross-sectional view showing the configuration of an electric heater and a high-temperature heat storage medium according to an embodiment of the present invention. [Figure 4A] 1 is an enlarged front view of a portion of a high-temperature heat storage body according to an embodiment of the present invention; [Figure 4B] 4B is a cross-sectional view of the high-temperature heat storage body of FIG. 4A taken along line AA. [Figure 5] 1 is a cross-sectional view showing the configuration of a low-temperature heat storage body according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing a phase transition cycle in a latent heat storage material according to an embodiment of the present invention. [Figure 7] 1 is a schematic diagram showing a configuration of a heat supply system according to an embodiment of the present invention. [Figure 8] 1 is a cross-sectional view showing a configuration of a melting device according to an embodiment of the present invention. [Figure 9] 1 is a cross-sectional view showing a configuration of a heat radiation recovery device according to an embodiment of the present invention. [Figure 10] 3 is a flowchart showing the flow of a heat supply method according to an embodiment of the present invention. [Figure 11] FIG. 10 is a cross-sectional view showing the configuration of a low-temperature heat storage body according to a modified example of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] A Carnot battery and an energy storage system according to an embodiment of the present invention will be described in detail below with reference to the drawings. In each drawing, the same or equivalent parts are designated by the same reference numerals.

[0010] The energy storage system according to the embodiment converts grid power, which has large output fluctuations, into stable generated power, which has small output fluctuations, using a high-temperature thermal storage material, and recovers the heat generated when converting grid power into generated power using a low-temperature thermal storage material, thereby supplying heat to heat demand areas. In the heat supply, hot water is supplied to consumers through pipes, and the consumers use the hot water for hot water supply, heating, snow melting, and other purposes.

[0011] Both the high-temperature heat storage material and the low-temperature heat storage material are phase change materials (PCMs) that store heat by utilizing latent heat. The latent heat storage material absorbs or releases heat by utilizing latent heat associated with a phase change between liquid and solid, and therefore has a higher heat storage density than the sensible heat storage material. The melting point of the high-temperature heat storage material is, for example, within a range of 500°C to 700°C, and the high-temperature heat storage material releases high-temperature air within a range of 500°C to 700°C. The melting point of the low-temperature heat storage material is lower than that of the high-temperature heat storage material, for example, within a range of 100°C to 200°C. The low-temperature heat storage material supplies hot water within a range of, for example, 70°C to 80°C when releasing heat.

[0012] Grid power is power supplied from a grid power source and may include fluctuating power derived from renewable energy. Renewable energy-derived power is, for example, power obtained from wind power, solar power, or tidal power, and has the characteristic that the amount of power generated is affected by external conditions such as weather, season, and time of day. Hereinafter, grid power includes fluctuating power derived from renewable energy and is assumed to exhibit short-term fluctuations. Short-term fluctuations are fluctuations in the amount of power that occur in periods of 20 minutes or less.

[0013] 1, the energy storage system 1 includes a Carnot battery 10 that converts grid power, which has large output fluctuations, into stable generated power, which has small output fluctuations, and a heat supply system 20 that recovers heat discharged from the Carnot battery 10 and supplies it to areas where heat is in demand. The heat supply system 20 recovers, for example, heat contained in the exhaust gas generated when the Carnot battery 10 converts heat into electricity.

[0014] The Carnot battery 10 comprises a heat source device 11 that converts grid power into heat, a high-temperature heat storage medium 12 that accumulates and releases the heat generated by the heat source device 11, and a steam power generation plant 13 that generates power by generating steam using the heat released from the high-temperature heat storage medium 12. The heat source device 11 is an example of a first conversion means that converts power into heat to generate high-temperature air, and the steam power generation plant 13 is an example of a second conversion means that recovers heat from the high-temperature air supplied from the high-temperature heat storage medium and converts it into power.

[0015] The heat supply system 20 is configured to be detachable from the steam power plant 13 and includes a low-temperature heat storage body 21 that recovers and stores heat discharged from the steam power plant 13, and a heat radiation recovery device 22 that is configured to be able to attach the low-temperature heat storage body 21 and recovers heat radiated from the low-temperature heat storage body 21 and supplies heat to a heat demand area. The heat supply system 20 may recover heat from the steam power plant 13 and release heat in the heat radiation recovery device 22 by using multiple low-temperature heat storage bodies 21 sequentially or simultaneously.

[0016] The low-temperature heat storage body 21 is a cartridge configured to be transportable by transportation means, for example, a truck. The low-temperature heat storage body 21 can be transported to a heat demand area and supplied with heat while set in the heat radiation recovery device 22. As an example, the low-temperature heat storage body 21 can store and store heat in the summer when heat storage is easy, and then be set in the heat radiation recovery device 22 in the winter when heat demand increases, and heat can be supplied using the heat released from the low-temperature heat storage body 21.

[0017] Next, each component of the Carnot battery 10 according to the embodiment will be described. 2, the heat source device 11 includes an electric heater 11a that generates thermal energy from electric power and a blower 11b that blows air toward the electric heater 11a to generate a wind of high-temperature air. The electric heater 11a includes, for example, a resistance heating element that generates thermal energy by the Joule effect. As long as grid power is supplied, the heat source device 11 receives the grid power, converts it into heat, and continues to supply it to the high-temperature thermal storage body 12.

[0018] The high-temperature heat storage body 12 includes a PCM with a large heat capacity, and is installed downstream of the heat source equipment 11. The high-temperature heat storage body 12 receives the high-temperature air supplied from the heat source equipment 11 and stores the heat, and also releases the heat to the surrounding high-temperature air as long as heat is stored. In other words, the high-temperature heat storage body 12 adjusts the temperature of the high-temperature air flowing from the heat source equipment 11 to a constant value as long as heat is stored.

[0019] The melting point of the PCM in the high-temperature heat storage body 12 is, for example, 570°C, and the temperature of the high-temperature air released by the high-temperature heat storage body 12 is, for example, in the range of 570°C to 600°C. A large heat dissipation reaction occurs when the PCM solidifies, and the amount of heat generated is controlled to be constant even when the grid power decreases, so that the inertial force is maintained. Therefore, it is preferable that the high-temperature heat storage body 12 stores and releases heat in a state where the latent heat storage material is molten inside the covering member.

[0020] As shown in Fig. 3, the heat source device 11 and the high-temperature storage body 12 are installed, for example, in a pipe 14. The high-temperature storage body 12 is formed with a plurality of passages that are adjacent to each other and extend in the same direction, allowing air to pass through. High-temperature air sent by the blower 11b passes through each passage, and exchanges heat with the wall surface. The high-temperature storage body 12 may have, for example, a honeycomb structure with an array of regular hexagonal holes, or a checkered brick structure with an array of circular holes.

[0021] As shown in Figures 4A and 4B, the high-temperature heat storage medium 12 is formed by combining a large number of PCM capsules 12A. The PCM capsules 12A are formed, for example, as spheres with a diameter of approximately 5 mm to 10 mm, and include a core made of latent heat storage material and a shell that covers the core. In consideration of the melting point of the latent heat storage material, the core is preferably made of 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% silicon is added to aluminum.

[0022] The shell is an example of a covering member that covers the latent heat storage material. The shell is preferably made of a ceramic material, such as alumina (Al2O3), which is obtained by oxidizing an aluminum alloy. Because the shell of the PCM capsule 12A is made of heat-resistant ceramic, it can prevent the shell from being damaged by heat or external force and causing the molten core to leak.

[0023] The heater capacity of the heat source device 11 may be, for example, about three times the average input power from the grid power supply, and the heat storage capacity of the high-temperature heat storage medium 12 may be, for example, a capacity equivalent to the amount of power obtained when the average input power from the grid power is used for 12 hours. As an example, if the average input power is 5 MW, the heater capacity of the heat source device 11 is 5 MW x 3 = 15 MW, and the heat storage capacity of the high-temperature heat storage medium 12 is 5 MW x 12 hours = 60 MWh if the heat generation efficiency of the heat source device 11 is 100%.

[0024] 2, the steam power plant 13 includes a steam boiler 13a that generates steam using high-temperature air from the high-temperature regenerator 12, a superheater 13b that superheats the steam generated in the steam boiler 13a, a steam turbine 13c that extracts rotational energy from the steam supplied from the superheater 13b, a generator 13d that generates electricity using the rotational energy from the steam turbine 13c, a condenser 13e that condenses the steam discharged from the steam turbine 13c, and a feedwater pump 13f that supplies the water condensed in the condenser 13e to the steam boiler 13a. Each part of the steam power plant 13 is connected in order via piping that can supply steam or water, and is configured to circulate steam or water within the steam power plant 13.

[0025] The steam boiler 13a takes in high-temperature air from the high-temperature regenerator 12 and converts water supplied from the feedwater pump 13f into saturated steam. The steam boiler 13a includes a drum that stores the water supplied from the feedwater pump 13f, and multiple pipes that are installed inside the drum and through which heated air from the high-temperature regenerator 12 passes to heat the water inside the drum and generate steam. The steam boiler 13a receives high-temperature air, for example, in the range of 570°C to 600°C from the high-temperature regenerator 12, and discharges air at 180°C as exhaust air. This exhaust air is used for heat storage in the low-temperature regenerator 21.

[0026] The superheater 13b heats the saturated steam generated in the steam boiler 13a with high-temperature air from the high-temperature regenerator 12, and changes it into superheated steam.

[0027] The steam turbine 13c converts the thermal energy of the superheated steam into rotational energy via an impeller and a rotating shaft. The rotating shaft of the steam turbine 13c is connected to the rotating shaft of the generator 13d and rotates the rotating shaft of the generator 13d around its axis.

[0028] The generator 13d converts the rotational energy of the steam turbine 13c into electrical energy. If the power generation output of the generator 13d is set to 1 MW, the steam turbine efficiency is about 25%.

[0029] The condenser 13e cools and condenses the wet steam discharged from the steam turbine 13c and reduces the exhaust pressure of the steam turbine 13c. A number of cooling pipes are arranged inside the tank of the condenser 13e, and the wet steam in the tank can be condensed by passing cooling water through these cooling pipes. At this time, the cooling water that passes through the cooling pipes turns into hot water, which can be used to supply heat to nearby sites.

[0030] The water supply pump 13f is a pump that supplies the water condensed by the condenser 13e to the steam boiler 13a. The above is the configuration of each part of the Carnot battery 10.

[0031] Next, each component of the heat supply system 20 according to the embodiment will be described. Returning to FIG. 1 , the low-temperature heat storage body 21 is a movable cartridge equipped with a PCM that melts at a lower temperature than the PCM in the high-temperature heat storage body 12. For example, assuming that the exhaust temperature from the steam boiler 13a is 180°C, the melting point of the PCM in the low-temperature heat storage body 21 is preferably in the range of 140°C to 160°C, and more preferably 150°C. The PCM in the low-temperature heat storage body 21 melts and changes to a heat-storing state due to the exhaust from the steam boiler 13a, and can supply heat in a heat-demanding area at a temperature in the range of 70°C to 80°C, for example. Hereinafter, the PCM in the low-temperature heat storage body 21 may be referred to as a "low-temperature PCM" to distinguish it from the PCM in the high-temperature heat storage body 12.

[0032] As shown in Fig. 5, the low-temperature heat storage body 21 includes a large number of PCM capsules 21A and a container 21B that accommodates the PCM capsules 21A and is formed to allow heat transfer between the PCM capsules 21A and the outside. The low-temperature heat storage body 21 stores, moves, and releases heat from the PCM capsules 21A while keeping the PCM capsules 21A accommodated inside the container 21B. The PCM capsules 21A are formed by encapsulating low-temperature PCM in alloy capsules, and their particle diameter is, for example, within a range of 1 mm to 10 mm. The capsules of the PCM capsules 21A are an example of a coating member that coats the low-temperature PCM. The container 21B is formed from a heat-transfer material, for example, a metal material. The container 21B may be formed in a cubic shape so that it can be stacked on top of each other. The container 21B may also be provided with a door that allows the PCM capsules 21A to be inserted and removed.

[0033] The low-temperature PCM of the low-temperature heat storage body 21 is preferably a substance that undergoes a phase transition from a molten state to a glassy state via a supercooled liquid state when cooled from the molten state at a certain rate or higher. The supercooled liquid state is a state in which a liquid remains liquid even when cooled below its melting point, and the glassy state is an amorphous state that occurs at temperatures lower than the glass transition point. A substance that undergoes a phase transition to a glassy state stores heat when changing from a crystalline state to a molten state, and can maintain the heat storage state by changing to the glassy state. Furthermore, by temporarily applying heat above the cold crystallization point to a substance in the glassy state, cold crystallization can be induced, releasing latent heat.

[0034] Specifically, as shown in Figure 6, when a substance that undergoes a glassy phase transition is cooled from a molten state at a certain rate or faster, it transitions through a supercooled liquid state to the glassy state at the glass transition point without releasing the latent heat of crystallization. Because a substance in a glassy state is an amorphous solid, it can be stored stably for long periods of time while maintaining its heat storage state, even at low temperatures. When a portion of a substance in a glassy state is heated, it transitions to a supercooled liquid state at the glass transition point. If further heating is continued, it changes to a cold crystalline state at the cold crystallization point. At this time, latent heat is released to the outside. If the crystals obtained by cold crystallization are heated above the melting point, they can be returned to a molten state. In this way, substances that undergo a glassy phase transition can store and release heat through a cycle of molten state, supercooled liquid state, glass state, supercooled liquid state, cold crystallization, and crystalline state.

[0035] The substance that undergoes a phase transition to a glassy state is, for example, a polyhydric alcohol, preferably a sugar alcohol. The sugar alcohol is a linear or cyclic polyhydric alcohol in which the carbonyl group of a sugar is reduced. As the sugar alcohol, it is preferable to use a eutectic formed from two or more types of sugar alcohols, and it is more preferable to use, for example, a ternary sugar alcohol formed from three types of sugar alcohols. An example of a ternary sugar alcohol is a eutectic of mannitol, galactitol, and inositol. By adjusting the composition of this eutectic, it is possible to change the melting point, latent heat of fusion, cold crystallization point, and latent heat of cold crystallization.

[0036] The glass transition point of a substance that undergoes a phase transition to a glass state is preferably within a range of, for example, 10°C to 50°C, the melting point (heat storage temperature) is preferably within a range of, for example, 100°C to 200°C, and the cold crystallization point (heat release onset temperature) is higher than the glass transition point but lower than the melting point, preferably within a range of, for example, 50°C to 100°C. As an example, a eutectic of mannitol, galactitol, and inositol (=0.557 mol:0.273 mol:0.206 mol) has a melting point of 150°C, a glass transition point upon cooling of 16.1°C, a glass transition point upon heating of 15.2°C, a cold crystallization point of 72.8°C, a latent heat of fusion of 248 kJ / kg, and a latent heat of cold crystallization of 157 kJ / kg. A large amount of latent heat can be released from a eutectic of mannitol, galactitol, and inositol in a glass state by temporarily applying heat so that a portion of the eutectic reaches a temperature of about 90°C.

[0037] Although cooling to -25°C or below is necessary to maintain the glassy state for about a year, it is not necessary to cool the material to the glassy state to maintain the heat storage state of a material that undergoes a phase transition to the glassy state. If the material is rapidly cooled to a temperature around room temperature (for example, around 40°C), it solidifies into a rubber-like 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 material 21 during storage, and handling is greatly improved.

[0038] 7, the heat supply system 20 further includes, in addition to the low-temperature heat storage body 21 and the heat radiation recovery device 22, a melter 23 that melts the low-temperature PCM in the low-temperature heat storage body 21, a quencher 24 that quenches the low-temperature PCM, a storage warehouse 25 that stores the low-temperature heat storage body 21, and a truck 26 that transports the low-temperature heat storage body 21. In the heat supply system 20, the low-temperature heat storage body 21 moves through the melter 23, the quencher 24, the storage warehouse 25, the truck 26, and the heat radiation recovery device 22 in this order.

[0039] Taking a low-temperature PCM with a melting point of 150°C, a glass transition point upon cooling of 16.1°C, and a cold crystallization point of 72.8°C as an example, melter 23 melts the low-temperature PCM using exhaust air from steam boiler 13a at 180°C, and releases the exhaust air at 140°C into the atmosphere. Quencher 24 rapidly cools the low-temperature PCM, transforming it from a molten state into a glassy state, which stores heat. After storage in the glassy state and transportation to a heat-demanding area, heat recovery unit 22 temporarily heats a portion of the low-temperature PCM to a temperature higher than the cold crystallization point, for example, around 90°C, thereby generating latent heat from the low-temperature PCM and transforming 20°C cold water into hot water in the range of 70°C to 80°C.

[0040] The melter 23 is configured to be able to accommodate the low-temperature heat storage body 21 therein, and uses exhaust air from the steam boiler 13a to melt the low-temperature PCM in the low-temperature heat storage body 21. As shown in Fig. 8, the melter 23 includes a housing 23a that accommodates the low-temperature heat storage body 21 therein, and a pair of heat exchangers 23b that are arranged within the housing 23a to sandwich both side surfaces of the low-temperature heat storage body 21 and heat both side surfaces of the low-temperature heat storage body 21 by heat transfer.

[0041] The housing 23a is open at the front and rear to allow movement of a cart 23e carrying the low-temperature heat storage body 21. Each heat exchanger 23b is connected to an intake pipe 23c that is connected to the steam boiler 13a and that supplies exhaust gas from the steam boiler 13a, and an exhaust pipe 23d that discharges exhaust gas after heat exchange.

[0042] Returning to Fig. 7, the quencher 24 is configured to be able to accommodate the low-temperature heat storage body 21 therein, and uses the cooling pipes of the condenser 13e to cause the molten low-temperature PCM contained in the low-temperature heat storage body 21 to undergo a phase transition to a glass state. The cooling pipes of the condenser 13e are connected to a heat exchanger disposed inside the quencher 24, and the quencher 24 cools both side surfaces of the low-temperature heat storage body 21 by heat transfer. The quencher 24 has the same or equivalent configuration as the melter 23, except that cooling water flows through the heat exchanger, for example.

[0043] 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 while maintaining the heat storage state to the heat demand area. To maintain the heat storage state of the low-temperature heat storage body 21, it is sufficient to suppress the temperature of the low-temperature heat storage body 21 to be equal to or lower than the glass transition point of the low-temperature PCM. Note that if the low-temperature PCM is stored in a rubber-like solidified state, the installation of air conditioning equipment in the storage warehouse 25 and the truck 26 may be omitted.

[0044] The heat dissipation recovery device 22 is configured so that the low-temperature heat storage body 21 can be installed inside, and by temporarily heating the low-temperature heat storage body 21, cold crystallization of the low-temperature PCM occurs, causing a large amount of latent heat to be released. As shown in Fig. 9, the heat dissipation recovery device 22 includes a housing 22a that houses the low-temperature heat storage body 21 inside, a heater 22b that is disposed inside the housing 22a and temporarily heats a portion of the low-temperature PCM in the low-temperature heat storage body 21 to a temperature higher than the cold crystallization point, and a heat exchanger 22c that is disposed inside the housing 22a and converts cold water supplied from outside into hot water by heat transfer in contact with the low-temperature heat storage body 21.

[0045] The housing 22a is provided with a door for inserting and removing the low-temperature heat storage body 21. A container lift machine, for example, may be used to store the low-temperature heat storage body 21 in the heat radiation recovery device 22. The heater 22b is disposed, for example, in the housing 22a so as to be in contact with the bottom and side surfaces of the low-temperature heat storage body 21, and the heat exchanger 22c is disposed, for example, on the upper side in the housing 22a. The components of the heat supply system 20 have been described above.

[0046] Next, the flow of the heat supply method according to the embodiment will be described with reference to Fig. 10. In the following, it is assumed that the low-temperature PCM in the low-temperature heat storage body 21 is in a crystalline state before being set in the melter 23.

[0047] First, the low-temperature heat storage body 21 is set in the melter 23, and the low-temperature PCM in the low-temperature heat storage body 21 is changed into a molten state using exhaust air from the steam boiler 13a (step S1). Specifically, as shown in Fig. 8, the low-temperature heat storage body 21 is placed on a cart 23e and placed in the melter 23, and the low-temperature PCM in the low-temperature heat storage body 21 is melted by the heat exchanger 23b heated by exhaust air from the steam boiler 13a.

[0048] Next, the low-temperature heat storage body 21 changed to a molten state in the process of step S1 is set in the quencher 24, and is rapidly cooled using cooling water from the condenser 13e, thereby changing the low-temperature PCM in the low-temperature heat storage body 21 to a glassy state (step S2). Specifically, the low-temperature heat storage body 21 placed on the cart 23e is set in the quencher 24 having a configuration equivalent to the melter 23 shown in Fig. 8, and the low-temperature PCM in the low-temperature heat storage body 21 is rapidly cooled to below its glass transition point, whereby the low-temperature PCM changes from a supercooled liquid state to a glassy state.

[0049] Next, the low-temperature heat storage material 21 that has been changed to a heat storage state in step S2 is stored in a storage warehouse 25 (step S3), and when heat demand arises, it is transported to a heat demand area using a truck 26 (step S4). In the storage warehouse 25 and the truck 26, the low-temperature PCM is maintained at a temperature below its glass transition point, thereby maintaining the heat storage state of the low-temperature PCM.

[0050] Next, the low-temperature heat storage material 21 is set in the heat radiation recovery device 22 located in the heat demand area, and heat is released from the low-temperature heat storage material 21 to supply heat to the heat demand area (step S5). Specifically, as shown in Fig. 9, when a portion of the low-temperature PCM in a glassy state is temporarily heated using heater 26b to a temperature above the cold crystallization point, the low-temperature PCM changes from a supercooled liquid state to a cold crystalline state and then to a crystalline state. At this time, cold crystallization latent heat is released as the cold crystallization progresses, so the latent heat can be recovered in heat exchanger 26c, and cold water of about 20°C can be changed to hot water of about 70 to 80°C.

[0051] Next, the low-temperature heat storage material 21 in the crystalline state is returned to the steam power plant 13 (step S6). The used low-temperature heat storage material 21 can be returned to the installation location of the steam power plant 13 using a truck 26. The low-temperature heat storage material 21 in the crystalline state can be set again in the melter 23 and the same process repeated, thereby making it possible to reuse the low-temperature heat storage material 21 as a heat source. The above is the flow of the heat supply method.

[0052] As described above, the Carnot battery 10 according to the embodiment comprises the heat source device 11 that converts electric power into heat to generate high-temperature air, the high-temperature heat storage body 12 that is provided downstream of the heat source device 11 and contains a latent heat storage material that receives the high-temperature air supplied from the heat source device 11, stores heat, and releases it, and the steam power generation plant 13 that is provided downstream of the high-temperature heat storage body 12 and recovers heat from the high-temperature air supplied from the high-temperature heat storage body 12 and converts it into electric power. Therefore, the large heat capacity of the high-temperature heat storage body 12 can absorb short-cycle fluctuations in grid power, including power derived from renewable energy, and as a result, grid power with large output fluctuations can be stably converted into generated power with small output fluctuations.

[0053] The energy storage system 1 according to the embodiment includes a Carnot battery 10, a low-temperature heat storage body 21 that is detachably attached to a steam power plant 13 of the Carnot battery 10 and includes a low-temperature PCM that collects and stores heat discharged from the steam power plant 13, and a heat radiation recovery device 22 that is attachable to the low-temperature heat storage body 21 and collects heat radiation from the low-temperature heat storage body 21 to supply heat to areas where heat is demanded. This makes it possible to recover low-level thermal energy (surplus heat) generated in the Carnot battery 10 and supply heat to areas where heat is demanded. As a result, the thermal utilization rate of the energy storage system 1 can be improved.

[0054] The present invention is not limited to the above-described embodiment, and the following modifications are possible.

[0055] (Variation) In the above embodiment, electric power is converted into heat by the heat source equipment 11, and heat is converted into electric power by the steam power generation plant 13, but the present invention is not limited to this. For example, a heat pump may be used to convert electric power into heat and heat into electric power.

[0056] In the above embodiment, the high-temperature storage body 12 has a plurality of passages through which air can pass formed adjacent to each other and extending in the same direction, but the present invention is not limited to this. The high-temperature storage body 12 may have any shape as long as it has a structure that allows heat exchange with air, and may be formed, for example, with a mesh structure.

[0057] In the above embodiment, the high-temperature heat storage medium 12 is formed by combining a large number of spherical PCM capsules 12A, but the present invention is not limited to this. The PCM capsules 12A may be formed, for example, in a block or cylindrical shape.

[0058] In the above embodiment, the particle size of the PCM capsules 12A is within the range of 1 mm to 10 mm, but the present invention is not limited to this. For example, the PCM capsules 12A may be formed as fine particles with a particle size within the range of 1 μm to 1 mm, and the fine particle PCM capsules 12A may be placed in a mold and bonded or sintered to create a high-temperature heat storage medium 12 of any shape.

[0059] 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 to this. For example, a blower that sends the exhaust gas from the steam boiler 13a to the melter 23 may be provided in the middle of the piping connecting the steam boiler 13a and the melter 23.

[0060] In the above embodiment, heat is stored in the low-temperature heat storage body 21 by exhaust air from the steam boiler 13a, but the present invention is not limited to this. For example, heat may be stored in the low-temperature heat storage body 21 by extracting air from the steam turbine 13c.

[0061] In the above embodiment, the container 21B containing the multiple PCM capsules 21A has a cubic shape. However, the present invention is not limited to this. For example, the container 21B may be a cylindrical container with an internal space. As shown in FIG. 11 , the container 21B may include a housing 21a and a pair of partition plates 21b disposed inside the housing 21a and containing the PCM capsules 21A therebetween. The housing 21a has through-holes 21c at both ends thereof, allowing air to pass through, and the partition plates 21b have multiple through-holes 21d, allowing air to pass through. Therefore, exhaust air from the steam boiler 13a can be directly ventilated into the housing 21a through the through-holes 21c, allowing heat to be stored in the PCM capsules 21A.

[0062] In the above embodiment, the low-temperature storage body 21 includes a large number of spherical PCM capsules 21A, but the present invention is not limited to this. The PCM capsules 21A may be formed, for example, in a block or cylindrical shape.

[0063] In the above embodiment, a large number of PCM capsules 21A are housed in the container 21B, but the present invention is not limited to this. A single low-temperature storage body 21 may be formed by joining a large number of PCM capsules 21A together. Furthermore, in the above embodiment, the particle size of the PCM capsules 21A is within a range of 1 mm to 10 mm, but the present invention is not limited to this. For example, the particle size of the PCM capsules 21A may be within a range of 1 μm to 1 mm, and a low-temperature storage body 21 of any shape may be formed by joining such minute PCM capsules 21A.

[0064] In the above embodiment, a PCM that undergoes a phase transition to a glassy state is used as the low-temperature PCM, but the present invention is not limited to this. If it is not necessary to store the low-temperature PCM in a heat-storing state for a long period of time, a PCM that does not undergo a phase transition to a glassy state may be used as the low-temperature PCM.

[0065] In the above embodiment, the melter 23 and the quench cooler 24 are configured to heat or cool both side surfaces of the low-temperature storage body 21 while the low-temperature storage body 21 is placed on the cart 23e, but the present invention is not limited to this. For example, the melter 23 may be configured to heat the low-temperature storage body 21 from below by a heat exchanger installed on the bottom surface of the housing 23a. Furthermore, the quench cooler 24 may be configured to cool the low-temperature storage body 21 from above by a heat exchanger installed on the top surface of the housing.

[0066] The above-described embodiments are merely examples, and the present invention is not limited to these. Various embodiments are possible within the scope of the invention as set forth in the claims. The components described in the embodiments and modifications can be freely combined. Furthermore, inventions equivalent to the inventions set forth in the claims are also included in the present invention. [Industrial Applicability]

[0067] The Carnot battery and energy storage system of the present invention are useful because they can stably supply power that absorbs output fluctuations derived from renewable energy. [Explanation of symbols]

[0068] 1 Energy storage system 10 Carnot Battery 11 Heat source equipment 11b Blower 12 High temperature heat storage body 12A, 21A PCM capsule 13 Steam Power Plant 13a Steam boiler 13c Steam turbine 13e Condenser 20 Heat supply system 21 Low temperature heat storage body 21B Container 22 Heat recovery device 23 Melter 24 Quench

Claims

1. a first conversion means for converting electrical power into heat to generate hot air; a high-temperature heat storage body that is provided downstream of the first conversion means in the flow path, includes a latent heat storage material that stores and releases heat between the high-temperature air supplied from the first conversion means, and adjusts the temperature of the high-temperature air by coming into contact with the high-temperature air; a second conversion means provided downstream of the high-temperature heat storage body in the flow path, for recovering heat from the high-temperature air supplied from the high-temperature heat storage body and converting the heat into electric power; The melting point of the latent heat storage material is in the range of 500°C to 700°C. Carnot battery.

2. The high-temperature storage medium includes a covering member that covers the latent heat storage material, The latent heat storage material stores and releases heat in a molten state inside the covering member.

2. The Carnot battery according to claim 1.

3. the first conversion means includes a blower that blows high-temperature air toward the high-temperature regenerator, The high-temperature storage body is arranged side by side so as to extend in the same direction, and includes a plurality of passages through which the high-temperature air blown from the blower passes.

3. The Carnot battery according to claim 1 or 2.

4. The high-temperature heat storage body is configured by combining a number of PCM capsules in which the latent heat storage material is covered with the covering member.

3. The Carnot battery according to claim 2.

5. The Carnot battery of claim 1; a low-temperature heat storage body that is detachably attached to the second conversion means of the Carnot battery and includes a latent heat storage material that recovers and stores heat discharged from the second conversion means; a heat recovery device that is configured to be able to mount the low-temperature heat storage body and recovers heat radiation from the low-temperature heat storage body to supply heat to a heat demand area; An energy storage system comprising:

6. The low-temperature heat storage body is A number of PCM capsules each having a latent heat storage material covered with a covering member; a container that accommodates a large number of PCM capsules therein and is formed to allow heat transfer between the PCM capsules and the outside; The energy storage system according to claim 5 .

7. A first conversion means for converting electric power into heat to generate high-temperature air; a high-temperature heat storage body provided downstream of the first conversion means, the high-temperature heat storage body including a latent heat storage material that receives the high-temperature air supplied from the first conversion means, stores heat therein, and releases the heat; a Carnot battery including a second conversion means provided downstream of the high-temperature regenerator and configured to recover heat from the high-temperature air supplied from the high-temperature regenerator and convert the heat into electric power; a low-temperature heat storage body that is detachably attached to the second conversion means and includes a latent heat storage material that recovers and stores heat discharged from the second conversion means; a heat recovery device configured to be able to mount the low-temperature heat storage body and recovering heat radiation from the low-temperature heat storage body to supply heat to a heat demand area, the second conversion means is a steam power plant that generates steam in a steam boiler using the heat released by the high-temperature regenerator and drives a steam turbine using the steam generated in the steam boiler; The energy storage system further includes a melter connected to the steam boiler, the melter melting the latent heat storage material contained in the low-temperature heat storage body by exhaust gas from the steam boiler. Energy storage system.

8. The low-temperature heat storage medium includes a latent heat storage material that undergoes a phase transition from a molten state to a supercooled liquid state and then to a glass state when rapidly cooled at a certain rate or more, The energy storage system includes a quencher connected to a condenser of the steam power plant, and causing a phase transition of the molten latent heat storage material contained in the low-temperature heat storage body to a glass state by cold water passing through a cooling pipe of the condenser. The energy storage system according to claim 7.

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