Thermal storage system

Abstract

This prevents heat from being released into the environment, making it possible to keep the incoming air from the fan from being too hot, or to increase the amount of heat stored per unit of electricity. [Solution] A heat storage system according to one embodiment comprises a heat storage tank that generates heat from an electric heater and stores the generated heat. In this heat storage system, the heat storage tank absorbs and stores heat from a fluid heated by a heat pump. This heat storage system further comprises a conveyor that circulates the fluid to the electric heater and the heat storage tank in that order. The heat pump absorbs heat from the fluid downstream of the heat storage tank and releases heat to the fluid upstream of the electric heater.

Description

Technical Field

[0001] Embodiments of the present invention relate to a heat storage system.

Background Art

[0002] In recent years, power generation using natural energy such as solar power generation and wind power generation has been increasing, and there are regions where the amount of power generation exceeds the power demand depending on the season and time zone. Also, depending on the season and time zone, the power demand increases, and there are times when the amount of power generation is less than the power demand and there is a power shortage. Therefore, a heat storage system that performs power adjustment using heat storage has been proposed.

[0003] FIG. 9 is a schematic diagram showing a schematic configuration of a conventional heat storage system. The heat storage system 201 shown in FIG. 9 includes a heat storage tank 1, an electric heater 2, a first blower 3, a second blower 4, a condensate pump 8, a boiler 9, a steam turbine 10, a condenser 11, valves 12 to 15, and a generator 30.

[0004] In the heat storage system 201, when the power is surplus, the condensate pump 8, the steam turbine 10, and the second blower 4 stop. Also, valves 12 and 13 open, and valves 14 and 15 close. Also, the electric heater 2 and the first blower 3 operate using the surplus power. The first blower 3 circulates air 5 between the electric heater 2 and the heat storage tank 1. The air 5 is heated by the heat generated by the electric heater 2. The heated air 5 is transported to the heat storage tank 1 and heats the heat storage material in the heat storage tank 1. Thereby, heat storage is performed. In this way, the heat storage operation is carried out.

[0005] Furthermore, in the thermal storage system 201, when there is no surplus power, the electric heater 2 and the first blower 3 are stopped. Also, valves 12 and 13 are closed and valves 14 and 15 are opened. In addition, the condensate pump 8 and the second blower 4 are operated. The second blower 4 circulates air 5 between the thermal storage tank 1 and the boiler 9. The air 5 is heated by the thermal storage material in the thermal storage tank 1. This heat is transported to the boiler 9. The boiler 9 heats the water 6 brought in by the condensate pump 8 with the heat from the air 5 to produce steam 7. As a result, the air 5 cools down and flows out. In this way, heat dissipation operation is carried out.

[0006] Steam 7 flows through the steam turbine 10 while becoming cold and low-pressure. This causes the steam turbine 10, which is the impeller, to rotate. As a result of this rotation, the generator 30, which is mechanically connected to the steam turbine 10, generates electricity.

[0007] The steam 7 discharged from the steam turbine 10 is cooled in the condenser 11 by cooling water, such as seawater, and converted into water 6. The water 6 is circulated between the boiler 9 and the steam turbine 10 by the condensate pump 8. In this way, the heat stored in the heat storage material in the heat storage tank 1 generates steam 7 and produces electricity.

[0008] Figure 10 is a schematic diagram showing the general configuration of a conventional thermal storage system, which differs from the thermal storage system 201 shown in Figure 9. Here, the same reference numerals are used for components that are the same as those in the thermal storage system 201 described above, and detailed explanations are omitted.

[0009] The heat storage system 201 described above has a closed cycle in which, during heat storage operation, a circulation path is formed in which air 5 is circulated between the electric heater 2 and the heat storage tank 1 by a first blower 3 located upstream of the electric heater 2. On the other hand, the heat storage system 202 shown in Figure 10 has an open cycle in which the air 5 that flows out of the heat storage tank 1 is released into the atmosphere.

[0010] Both thermal storage systems 201 and 202 regulate electricity by using electricity when there is a surplus and generating electricity when there is no surplus. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] International Publication No. 2016 / 050368 [Overview of the project] [Problems that the invention aims to solve]

[0012] In thermal storage systems 201 and 202, during thermal storage operation, the air 5 flowing into the thermal storage tank 1 transfers heat to the thermal storage material, causing its temperature to drop before it flows out. However, the outlet temperature from the thermal storage tank 1 is significantly higher than the inflow temperature of the first blower 3. Therefore, in the thermal storage system 201, which has a closed cycle, the volumetric flow rate of the air 5 flowing into the first blower 3 increases, resulting in a high load on the first blower 3. In some cases, the load may even exceed the heat resistance temperature of the first blower 3. Thus, in the thermal storage system 201, there is a need to cool the air flowing into the first blower 3.

[0013] On the other hand, the heat storage system 202 has an open cycle that releases the air 5 flowing out of the heat storage tank 1 into the atmosphere, so the load on the first blower 3 does not increase. However, in the heat storage system 201, when the air 5 is discharged from the heat storage tank 1 into the atmosphere, some of the heat heated by the power consumption of the electric heater 2 that was not supplied to the heat storage tank 1 is wasted into the atmosphere. Therefore, the heat storage system 202 has the challenge of reducing the amount of heat wasted into the outside atmosphere.

[0014] Furthermore, both thermal storage systems 201 and 202 face the challenge of increasing the amount of heat stored per unit of power consumption.

[0015] The problem that this invention aims to solve is to provide a heat storage system that does not release heat to the outside and can prevent the incoming air of a blower from becoming hot, and a heat storage system that can increase the amount of heat stored per unit of electricity. [Means for solving the problem]

[0016] A heat storage system according to an embodiment includes a heat storage tank that generates heat from an electric heater and stores the generated heat. In this heat storage system, the heat storage tank absorbs heat from a fluid heated by a heat pump and stores the heat. This heat storage system further includes a transporter that circulates the fluid through the electric heater and the heat storage tank in that order. The heat pump absorbs heat from the fluid downstream of the heat storage tank and releases heat to the fluid upstream of the electric heater.

Effects of the Invention

[0017] According to this embodiment, it is possible to avoid discarding heat to the outside, to make the inflowing air of the blower not hot, or to increase the amount of heat stored per unit of electric power.

Brief Description of the Drawings

[0018] [Figure 1] It is a schematic diagram showing a schematic configuration of a heat storage system according to the first embodiment. [Figure 2] It is a schematic diagram showing a schematic configuration of a heat storage system according to a modified example of the first embodiment. [Figure 3] It is a schematic diagram showing a schematic configuration of a heat storage system according to the second embodiment. [Figure 4] It is a schematic diagram showing a schematic configuration of a heat storage system according to the third embodiment. [Figure 5] It is a schematic diagram showing a schematic configuration of a heat storage system according to a modified example of the third embodiment. [Figure 6] It is a schematic diagram showing a schematic configuration of a heat storage system according to the fourth embodiment. [Figure 7] It is a schematic diagram showing a schematic configuration of a heat storage system according to the fifth embodiment. [Figure 8] It is a schematic diagram showing a schematic configuration of a heat storage system according to the sixth embodiment. [Figure 9] It is a schematic diagram showing a schematic configuration of a conventional heat storage system. [Figure 10] It is a schematic diagram showing a schematic configuration of a conventional heat storage system different from the heat storage system shown in FIG. 9.

Mode for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments do not limit the present invention.

[0020] (First Embodiment) FIG. 1 is a schematic diagram showing a schematic configuration of a heat storage system according to the first embodiment. In FIG. 1, the same reference numerals are given to the same components as those of the heat storage system 201 shown in FIG. 9. Note that FIG. 1 shows only the components related to the heat storage operation, and the description of the components related to the heat dissipation operation is omitted.

[0021] As shown in FIG. 1, the heat storage system 101 according to the present embodiment further includes a cooler 17, a heater 18, a heat pump 19, a first conveyor 22, and a second conveyor 23 in addition to the components of the heat storage system 202.

[0022] The cooler 17 is provided between the heat storage tank 1 and the first blower 3. The heater 18 is provided between the first blower 3 and the electric heater 2. The heat pump 19 is provided between the heater 18 and the cooler 17. The first conveyor 22 is provided between the cooler 17 and the heat pump 19. The second conveyor 23 is provided between the heater 18 and the heat pump 19.

[0023] The heat pump 19 is, for example, a heat transport device based on a vapor compression refrigeration cycle using a refrigerant such as Freon. The first conveyor 22 circulates the first heat medium 20 between the heat pump 19 and the cooler 17. The second conveyor 23 circulates the second heat medium 21 between the heat pump 19 and the heater 18.

[0024] Hereinafter, the heat storage operation of the heat storage system 101 configured as described above will be described.

[0025] When the heat storage system 101 is operating, valves 12 and 13 open, while valves 14 and 15 close, in accordance with the control signals input from the operation control device (not shown) of the heat storage system 101. In addition, the electric heater 2, the first blower 3, the second blower 4, the heat pump 19, the first conveyor 22, and the second conveyor 23 operate using commercial power.

[0026] The heat pump 19 cools the first heat transfer medium 20. The cooled first heat transfer medium 20 cools the outlet air of the heat storage tank 1 in the cooler 17. The heat pump 19 also heats the second heat transfer medium 21. The heated second heat transfer medium 21 heats the inlet air of the electric heater 2 in the heater 18. In this way, the heat pump 19 absorbs heat from the first fluid, which is the air flowing out of the heat storage tank 1, and heats the second fluid, which is the air 5 flowing into the electric heater 2. In heat storage operation, the relationship between the amount of heat heated by the heat pump 19 = amount of heat absorbed + electrical input holds true, so no heat loss occurs.

[0027] On the other hand, when the heat storage system 101 is operating in heat release mode, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the conventional heat storage system 201. However, in this embodiment, the use of the heat released from the heat storage tank 1 is not limited to being a heat source for the steam turbine 10; for example, it may be used for air conditioning.

[0028] According to this embodiment, the heat pump 19 can cool the incoming air to the first blower 3 without releasing the heat from the heat storage tank 1 into the atmosphere. This prevents the load on the first blower 3 from increasing and prevents the incoming air to the first blower 3 from exceeding its heat resistance temperature.

[0029] In this embodiment, the heat storage system 101 circulates air 5, but as long as the heat dissipation operation is also a closed cycle, a fluid other than the outside air 5 may be circulated.

[0030] Figure 2 is a schematic diagram showing the general configuration of a heat storage system according to a modified example of the first embodiment. In Figure 2, the same reference numerals are used for components similar to those in the heat storage system 101 according to the first embodiment described above, and detailed explanations are omitted.

[0031] The heat storage system 101a shown in Figure 2 is equipped with a heat storage tank 29 with a built-in electric heater. The heat storage tank 29 has an electric heater 2 built into the heat storage tank 1. In the heat storage tank 29, the built-in electric heater 2 generates heat during heat storage operation. According to this modified example, the inclusion of the electric heater-integrated heat storage tank 29 makes the system configuration more compact compared to the heat storage system 101 according to the first embodiment. In this modified example, the electric heater-integrated heat storage tank 29 has all of the electric heater 2 integrated into the heat storage tank 1, but it may also have a configuration in which only a part of the electric heater 2 is integrated into the electric heater-integrated heat storage tank 29.

[0032] (Second Embodiment) Figure 3 is a schematic diagram showing the general configuration of the heat storage system according to the second embodiment. In Figure 3, the same reference numerals are used for components similar to those in the heat storage system 101 according to the first embodiment shown in Figure 1, and detailed explanations are omitted. Note that Figure 3 only shows components related to heat storage operation, and components related to heat dissipation operation are not described.

[0033] The heat storage system 101 according to the first embodiment has a closed cycle, similar to the conventional heat storage system 201 shown in Figure 9. On the other hand, the heat storage system 102 according to this embodiment has an open cycle, similar to the conventional heat storage system 202 shown in Figure 10.

[0034] When the heat storage system 102 according to this embodiment is in heat storage operation, the heat pump 19 absorbs heat from the outlet air of the heat storage tank 1 and heats the inlet air of the electric heater 2, similar to the first embodiment. However, the air 5 that flows out of the heat storage tank 1 is released into the atmosphere.

[0035] Furthermore, when the heat storage system 102 is operating in heat release mode, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the conventional heat storage system 202. However, in this embodiment as well, the use of the heat released from the heat storage tank 1 is not limited to being a heat source for the steam turbine 10; for example, it may be used for air conditioning.

[0036] Furthermore, the heat storage system 102 according to this embodiment may also be provided with a heat storage tank 29 with a built-in electric heater, similar to the modified example of the first embodiment shown in Figure 2. In this case, the heat storage tank 29 with a built-in electric heater may be configured such that the entire electric heater 2 is built into the heat storage tank 1, or it may be configured such that a part of the electric heater 2 is built into the heat storage tank 29 with a built-in electric heater.

[0037] As described above, in this embodiment, similar to the first embodiment, the heat pump 19 absorbs heat from the outlet air of the heat storage tank 1. Therefore, compared to the conventional heat storage system 202, it is possible to reduce the amount of heat discharged into the atmosphere. Furthermore, in the heat pump 19 which has a heating coefficient of performance (COP), the amount of heat heated equals COP for every 1 unit of electrical input. COP is always greater than 1. As a result, in the heating part (heater 18) of the heat pump 19, the air 5 is heated more than the power consumption. In the electric heater 2, the amount of heat heated equals 1 unit of electrical input. Therefore, compared to the conventional heat storage system 202, the amount of air heated per unit of total power increases. Consequently, the effect of increasing the amount of heat stored per unit of total power can also be obtained.

[0038] (Third embodiment) Figure 4 is a schematic diagram showing the general configuration of a heat storage system according to the third embodiment. In Figure 4, the same reference numerals are used for components similar to those in the heat storage system 101 according to the first embodiment shown in Figure 1, and detailed explanations are omitted. Also, Figure 4 shows only the components related to heat storage operation, and components related to heat dissipation operation are not described.

[0039] As shown in Figure 4, the heat storage system 103 according to this embodiment does not have a cooler 17 and a first conveyor 22, but instead has an atmospheric blower 24. The atmospheric blower 24 operates on commercial power during heat storage operation.

[0040] When the heat storage system 103 according to this embodiment is in heat storage operation, the air 16 is circulated through the heat pump 19 by the air blower 24. In addition, the second heat transfer medium 21 is circulated between the heat pump 19 and the heater 18 by the second conveyor 23.

[0041] The heat pump 19 absorbs heat from the atmosphere 16 and also heats the second heat transfer medium 21. The heated second heat transfer medium 21 is then used by the heater 18 to heat the inlet air of the electric heater 2. In this way, during heat storage operation, the heat pump 19 absorbs heat from the first fluid, the atmosphere 16, and heats the second fluid, which is the air 5 flowing into the electric heater 2.

[0042] Furthermore, when the heat storage system 103 is in heat release operation, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the first embodiment. However, in this embodiment as well, the use of the heat released from the heat storage tank 1 is not limited to being a heat source for the steam turbine 10; for example, it may be used for air conditioning. Also, as with heat storage operation, a fluid other than air 5 may be circulated during heat release operation as long as it is a closed cycle. Note that the heat pump 19 absorbs heat from the atmosphere 16, but it does not have to be the atmosphere 16 as long as it is from the outside; for example, it may be waste hot water.

[0043] In this embodiment, the heat pump 19, which has a heating coefficient COP, heat output = COP for an electrical input of 1. COP is always greater than 1. As a result, in the heating portion (heater 18) of the heat pump 19, the air 5 is heated more than the power consumption. In the electric heater 2, heat output = 1 for an electrical input of 1. Therefore, in this embodiment as well, the amount of heat heated per unit of total power increases. Thus, the effect of increasing the amount of heat stored per unit of total power can be obtained.

[0044] Figure 5 is a schematic diagram showing the general configuration of a heat storage system according to a modified example of the third embodiment. In Figure 5, the same reference numerals are used for components similar to those in the heat storage system 103 according to the third embodiment described above, and detailed explanations are omitted.

[0045] The heat storage system 103a shown in Figure 5 is provided with a heat storage tank 29 with a built-in electric heater, similar to the modified version of the first embodiment. Therefore, according to this modified version, the heat storage tank 29 with a built-in electric heater makes the system configuration more compact compared to the heat storage system 103 according to the third embodiment. In addition, the heat storage tank 29 with a built-in electric heater according to this modified version may have all of the electric heater 2 built into the heat storage tank 1, or it may have part of the electric heater 2 built into the heat storage tank 29. Furthermore, although the heat pump 19 absorbs heat from the atmosphere 16, it does not have to be the atmosphere 16, as long as it is from the outside, for example, waste hot water may be used.

[0046] (Fourth Embodiment) Figure 6 is a schematic diagram showing the general configuration of the heat storage system according to the fourth embodiment. In Figure 6, the same reference numerals are used for components similar to those in the heat storage system 103 according to the third embodiment shown in Figure 4, and detailed explanations are omitted. Also, Figure 6 shows only the components related to the heat storage operation, and the components related to the heat dissipation operation are not described.

[0047] The heat storage system 103 according to the third embodiment has a closed cycle, similar to the heat storage system 101 according to the first embodiment. On the other hand, the heat storage system 104 according to this embodiment has an open cycle, similar to the heat storage system 102 according to the second embodiment.

[0048] When the heat storage system 104 according to this embodiment is in heat storage operation, the heat pump 19 absorbs heat from the atmosphere 16 and heats the inlet air of the electric heater 2, similar to the third embodiment. However, the air 5 that flows out of the heat storage tank 1 is discharged into the atmosphere.

[0049] Furthermore, when the heat storage system 104 is operating in heat release mode, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the third embodiment. However, in this embodiment as well, the use of the heat released from the heat storage tank 1 is not limited to being a heat source for the steam turbine 10; for example, it may be used for air conditioning.

[0050] Furthermore, the heat storage system 104 according to this embodiment may also be provided with a heat storage tank 29 with a built-in electric heater, similar to the modified example of the third embodiment shown in Figure 5. In this case, the heat storage tank 29 with a built-in electric heater may be configured such that the entire electric heater 2 is built into the heat storage tank 1, or it may be configured such that a part of the electric heater 2 is built into the heat storage tank 29 with a built-in electric heater.

[0051] In this embodiment described above, in a heat pump 19 having a heating coefficient of performance COP, the amount of heat generated = COP > 1 for an electrical input of 1. As a result, the air 5 is heated more than the power consumed in the heating portion (heater 18) of the heat pump 19. Therefore, in this embodiment as well, the amount of heat generated per unit of total power increases. Thus, the effect of increasing the amount of heat stored per unit of total power can be obtained. In this embodiment, the heat pump 19 absorbs heat from the atmosphere 16, but it does not have to be the atmosphere 16 as long as it is from the outside, for example, waste hot water may also be used.

[0052] (Fifth embodiment) Figure 7 is a schematic diagram showing the general configuration of the heat storage system according to the fifth embodiment. In Figure 7, the same reference numerals are used for components similar to those in the heat storage system 103 according to the third embodiment shown in Figure 4, and detailed explanations are omitted. Also, Figure 7 shows only the components related to the heat storage operation, and the components related to the heat dissipation operation are not described.

[0053] The heat storage system 105 according to this embodiment is equipped with a plurality of heat pumps, namely a first heat pump 26 and a second heat pump 27, and each heat pump is connected to the other. A third conveyor 28 is provided between the first heat pump 26 and the second heat pump 27.

[0054] When the heat storage system 105 according to this embodiment is in heat storage operation, the electric heater 2, the first blower 3, the second conveyor 23, the atmospheric blower 24, the first heat pump 26, the second heat pump 27, and the third conveyor 28 operate using commercial power.

[0055] The atmospheric fan 24 circulates the air 16 through the first heat pump 26. The third conveyor 28 circulates the third heat transfer medium 25 between the first heat pump 26 and the second heat pump 27. The second conveyor 23 circulates the second heat transfer medium 21 between the first heat pump 26 and the heater 18. The third heat transfer medium 25 is, for example, hot water.

[0056] The first heat pump 26 absorbs heat from the atmosphere 16 to heat the third heat transfer medium 25. The second heat pump 27 absorbs heat from the third heat transfer medium 25 to heat the second heat transfer medium 21. The second heat transfer medium 21 heats the inlet air of the electric heater 2 in the heater 18. In this way, the combination of the first heat pump 26 and the second heat pump 27 heats the inlet air of the electric heater 2 with heat absorbed from the atmosphere 16.

[0057] Furthermore, when the heat storage system 105 is in heat release operation, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the third embodiment. However, in this embodiment as well, the use of the heat released from the heat storage tank 1 is not limited to a heat source for the steam turbine 10; for example, it may be used for air conditioning. Also, as with heat storage operation, if the heat release operation is a closed cycle, a fluid other than air 5 may be circulated.

[0058] Furthermore, the heat storage system 104 according to this embodiment may also be provided with a heat storage tank 29 with a built-in electric heater, similar to the modified example of the third embodiment shown in Figure 5. In this case, the heat storage tank 29 with a built-in electric heater may be configured such that the entire electric heater 2 is built into the heat storage tank 1, or it may be configured such that a part of the electric heater 2 is built into the heat storage tank 29 with a built-in electric heater.

[0059] In this embodiment, the temperature of the second heat transfer medium 21 can be increased by connecting multiple heat pumps. This allows the air 5 to be heated to a higher temperature in the heater 18.

[0060] Furthermore, in this embodiment as well, in the heating portion (heater 18) of the heat pump 19 having a heating coefficient COP, the air 5 is heated to a greater extent than the power consumption. Also, in this embodiment, when heating the air 5 to a certain temperature, increasing the amount of heating by the heat pump 19 and decreasing the amount of heating by the electric heater 2 reduces power consumption while increasing the amount of heating per unit of total power. Therefore, in this embodiment as well, the effect of increasing the amount of heat stored per unit of total power can be obtained.

[0061] In this embodiment, a closed cycle is used, but an open cycle is also possible. Furthermore, a configuration in which multiple heat pumps are connected may be applied to the heat storage system 101 according to the first embodiment and the heat storage system 102 according to the second embodiment described above. In this case as well, the same effects as in this embodiment can be obtained. In addition, in this embodiment, the heat pump 19 absorbs heat from the atmosphere 16, but it does not have to be the atmosphere 16 as long as it is from the outside, for example, waste hot water may be used.

[0062] (Sixth Embodiment) Figure 8 is a schematic diagram showing the general configuration of the heat storage system according to the sixth embodiment. In Figure 8, the same reference numerals are used for components similar to those in the heat storage system 103 according to the third embodiment shown in Figure 4, and detailed explanations are omitted. Also, Figure 8 shows only the components related to the heat storage operation, and the components related to the heat dissipation operation are not described.

[0063] In this embodiment, it is assumed that the heat storage temperature of the heat storage tank 1, which is required as a heat source, can be achieved by the heat pump 19 alone, without the need for an electric heater 2.

[0064] In this embodiment, the heat storage system 106 does not have an electric heater 2 installed, and the heater 18 is connected to the heat storage tank 1 via a valve 12. When this heat storage system 106 is in heat storage operation, the first blower 3, heat pump 19, second conveyor 23, and atmospheric blower 24 are operated using commercial power.

[0065] The air blower 24 circulates the air 16 through the heat pump 19. The second conveyor 23 circulates the second heat transfer medium 21 between the heat pump 19 and the heater 18. The heat pump 19 absorbs heat from the air 16 and also heats the second heat transfer medium 21. The heated second heat transfer medium 21 is then used by the heater 18 to heat the inlet air of the heat storage tank 1. In this way, the heat pump 19 heats the inlet air of the heat storage tank 1 with the heat absorbed from the air 16.

[0066] Furthermore, when the heat storage system 106 is in heat release operation, the heat released from the heat storage tank 1 is used as a heat source for the steam turbine 10, similar to the third embodiment. However, in this embodiment as well, the use of the heat released from the heat storage tank 1 is not limited to a heat source for the steam turbine 10; for example, it may be used for air conditioning. Also, as with heat storage operation, if the heat release operation is a closed cycle, a fluid other than air 5 may be circulated.

[0067] In this embodiment, as in the third embodiment, the air 5 is heated to a greater extent than the power consumption in the heating portion (heater 18) of the heat pump 19 having a heating coefficient COP. Furthermore, in this embodiment, the amount of heating per unit of total power increases compared to the case where heating is performed by the electric heater 2 alone or by the electric heater 2 and the heat pump 19. Therefore, in this embodiment as well, the effect of increasing the amount of heat stored per unit of total power can be obtained.

[0068] In this embodiment, a closed cycle is used, but an open cycle is also possible. Furthermore, the configuration that eliminates the need for the electric heater 2, as in this embodiment, may also be applied to the heat storage system 101 according to the first embodiment, the heat storage system 102 according to the second embodiment, and the heat storage system 105 according to the fifth embodiment, respectively. In this case as well, the same effects as in this embodiment can be obtained. In addition, in this embodiment, the heat pump 19 absorbs heat from the atmosphere 16, but it does not have to be the atmosphere 16 as long as it is from the outside, for example, waste hot water may be used.

[0069] Although several embodiments have been described above, these embodiments are presented only as examples and are not intended to limit the scope of the invention. The novel system described herein can be implemented in a variety of other forms. Furthermore, various omissions, substitutions, and modifications can be made to the forms of the system described herein without departing from the spirit of the invention. The appended claims and equivalents are intended to include such forms and modifications that are included in the scope and spirit of the invention. [Explanation of Symbols]

[0070] 1: Heat storage tank 2: Electric heater 3: 1st blower 4:Second blower 5: Air 6:Water 7: Steam 8: Condensate pump 9: Boiler 10: Steam Turbine 11: Condenser 12-15: Valve 16: Atmosphere 17:Cooler 18: Heater 19: Heat pump 20: 1st heat medium 21:Second heat medium 22: First conveyor 23: Second transport machine 24: Atmospheric fan 25:Third heat medium 26: First heat pump 27: Second heat pump 28: Third conveyor 29: Heat storage tank with built-in electric heater 30: Generator 101-106, 201, 202: Thermal storage system

Claims

1. A heat storage system comprising a heat storage tank that generates heat from an electric heater and stores the generated heat, The aforementioned heat storage tank absorbs and stores heat from a fluid heated by a heat pump. The system further comprises a conveyor that circulates the aforementioned fluid to the electric heater and the heat storage tank in that order. The heat pump is a heat storage system that absorbs heat from the fluid downstream of the heat storage tank and releases heat to the fluid upstream of the electric heater.

2. A heat storage system comprising a heat storage tank that generates heat from an electric heater and stores the generated heat, The aforementioned heat storage tank absorbs and stores heat from a fluid heated by a heat pump. The electric heater is built into the heat storage tank, and the system further comprises a conveyor that circulates the fluid into the heat storage tank. The heat pump is a heat storage system that absorbs heat from the fluid downstream of the heat storage tank and releases heat to the fluid upstream of the heat storage tank.

3. The heat storage system according to claim 1 or 2, wherein the fluid is air drawn in from the atmosphere and is ultimately released from the heat storage tank back into the atmosphere.

4. The conveying machine is provided upstream of the electric heater. The system further comprises a heater provided between the conveyor and the electric heater, which heats the fluid with heat absorbed by the heat pump, The heat storage system according to claim 1, wherein the fluid flow path is a circulation path that circulates between the heater, the electric heater, and the heat storage tank by the conveyor.

5. The conveying machine is installed on the upstream side of the heat storage tank. The system further includes a heater provided between the conveyor and the heat storage tank, which heats the fluid with heat absorbed by the heat pump, The heat storage system according to claim 2, wherein the fluid flow path is a circulation path that circulates between the heater and the heat storage tank by the conveyor.

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