Compressed air energy storage device and energy storage device

Abstract

Provided is an energy storage device using compressed air and connected to a pneumatic device driven by air pressure, and the energy storage device comprises: an electric motor driven by electric power from a power transmission / distribution system to which a regenerative energy power generation device is connected; a compressor driven by the electric motor; an accumulator tank for storing compressed air compressed by the compressor as compressed air or liquid air; an expander driven by the compressed air stored in the accumulator tank; a power generator driven by the expander; a pipe through which the compressed air passes; a solenoid valve provided in the pipe; a pressure sensor for detecting a pressure of the pipe; and a control device for controlling the solenoid valve. The pipe includes a pneumatic supply pipe connected to the pneumatic device. The control device controls the solenoid valve to drive the expander by compressed air exceeding a predetermined pressure, and controls the solenoid valve to supply compressed air equal to or lower than the predetermined pressure from the pneumatic supply pipe to the pneumatic device.

Description

Compressed air energy storage device and energy storage device

[0001] The present invention relates to an energy storage device, in particular to a compressed air energy storage device and a liquid air energy storage device.

[0002] Power generation using renewable energy sources such as wind power and solar power depends on weather conditions, and therefore the amount of power generated can fluctuate and become unstable. To address such fluctuations, a compressed air energy storage (CAES) system or a liquid air energy storage (LAES) system is known as a system for leveling out power generation output.

[0003] An energy storage device (CAES device or LAES device) that utilizes this CAES system or LAES system stores electrical energy as compressed air or liquefied air in an accumulator tank, and when electricity is needed, the compressed air drives an expander to operate a generator, generating electrical energy and leveling out output.

[0004] In such CAES devices, for example, Patent Document 1 discloses a technology for controlling the output of power according to power demand by using a tank with a relatively large capacity for long-period fluctuating power generated by natural energy and a tank with a relatively small capacity for short-period fluctuating power, thereby leveling out both long-period and short-period fluctuating power.

[0005] Furthermore, Patent Document 2 discloses a technology that prevents a decrease in the operating efficiency of the entire system by controlling the expander bypass switching unit to allow air to flow into the expander bypass flow path and bypass the expander main body when the pressure in the accumulator tank detected by the pressure sensor is lower than a predetermined value.

[0006] Japanese Patent No. 6368577 Japanese Patent Application Laid-Open No. 2017-8867

[0007] In a CAES system, for example, when generating electricity using a solar power generation system, the CAES system stores energy by operating a compressor and storing compressed air during the daytime when surplus electricity is generated. However, during the daytime, production equipment in the factory is in heavy operation, and although the amount of electricity generated is high, the amount of electricity used is also high.

[0008] The technologies of Patent Documents 1 and 2 do not take into consideration efficient energy storage while meeting the daytime power demand of a factory. Therefore, there is room for improvement in order to effectively shift power from time periods with high power generation to time periods with low power generation (power leveling).

[0009] An object of the present invention is to provide an energy storage device that can achieve power leveling by adjusting the power supply and demand in a factory.

[0010] In order to solve the above problems, one representative energy storage device of the present invention is a compressed air energy storage device or liquid air energy storage device connected to pneumatic equipment driven by air pressure, and includes: an electric motor driven by power from a power transmission and distribution system to which a renewable energy power generation device is connected; a compressor driven by the electric motor; a pressure accumulator tank that stores the compressed air compressed by the compressor as compressed air or liquid air; an expander driven by the compressed air stored in the pressure accumulator tank; a generator driven by the expander; piping through which the compressed air passes; a solenoid valve provided in the piping; a pressure sensor that detects the pressure in the piping; and a control device that controls the solenoid valve, wherein the piping includes an air pressure supply piping connected to the pneumatic equipment, and the control device controls the solenoid valve to drive the expander with compressed air exceeding a predetermined pressure, and controls the solenoid valve to supply compressed air below the predetermined pressure from the air pressure supply piping to the pneumatic equipment.

[0011] According to the present invention, it is possible to achieve power leveling by adjusting the power supply and demand in a factory.

[0012] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0013] FIG. 1 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a first embodiment of the present invention. FIG. 2 is a flowchart showing an example of control of the CAES apparatus according to the first embodiment of the present invention. FIG. 3 is a diagram showing an example of operation of the CAES apparatus according to the first embodiment of the present invention. FIG. 4 is a diagram showing an example of operation of the CAES apparatus according to the first embodiment of the present invention. FIG. 5 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a second embodiment of the present invention. FIG. 6 is a flowchart showing an example of control of the CAES apparatus according to the second embodiment of the present invention. FIG. 7 is a diagram showing an example of operation of the CAES apparatus according to the second embodiment of the present invention. FIG. 8 is a diagram showing an example of operation of the CAES apparatus according to the second embodiment of the present invention. FIG. 9 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a third embodiment of the present invention. FIG. 10 is a diagram showing an example of operation of the CAES apparatus according to the third embodiment of the present invention. FIG. 11 is a diagram showing an example of operation of the CAES apparatus according to the third embodiment of the present invention. FIG. 12 is a diagram showing an example of operation of the CAES apparatus according to the third embodiment of the present invention. FIG. 13 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a fourth embodiment of the present invention. FIG. 14 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a fifth embodiment of the present invention. FIG. 15 is a flowchart showing an example of control of the CAES apparatus according to the fifth embodiment of the present invention. FIG. 16 is a diagram showing an example of operation of the CAES apparatus according to the fifth embodiment of the present invention. FIG. 17 is a diagram showing an example of operation of the CAES apparatus according to the fifth embodiment of the present invention. Fig. 1 is a schematic configuration diagram of an LAES apparatus according to a seventh embodiment of the present invention. Fig. 2 is a schematic configuration diagram of an LAES apparatus according to an eighth embodiment of the present invention. Fig. 3 is a schematic configuration diagram of an LAES apparatus according to a ninth embodiment of the present invention. Fig. 4 is a schematic configuration diagram of an LAES apparatus according to a tenth embodiment of the present invention. Fig. 5 is a schematic configuration diagram of an LAES apparatus according to an eleventh embodiment of the present invention. Fig. 6 is a schematic configuration diagram of an LAES apparatus according to a twelfth embodiment of the present invention.

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

[0015] (First Embodiment) (1-1) CAES Apparatus FIG. 1 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a first embodiment of the present invention.

[0016] The CAES device 1 is a device that levels the power (grid power) of a power transmission and distribution system 5 to which renewable energy power generation devices such as solar power generation devices 2 and wind power generation devices 3 are connected. The renewable energy power generation devices can supply power to a factory M, for example.

[0017] When the amount of power generated by the renewable energy power generation device is insufficient for the amount of power used by the factory M, the factory M makes up for the shortage with grid power. The renewable energy power generation device is also connected to the power transmission and distribution grid 5 via a power conditioner 4.

[0018] The CAES device 1 stores (charges) a portion of the grid power as compressed air energy when the amount of power generated by the renewable energy power generation device is large compared to the amount of power used in the factory M. Furthermore, when the amount of power generated by the renewable energy power generation device is small compared to the amount of power used in the factory M, the CAES device 1 generates power using the stored compressed air and returns (discharges) the power to the power transmission and distribution system 5. Furthermore, the CAES device 1 can supply compressed air to pneumatic equipment M1 that is driven by air pressure in the factory M.

[0019] The CAES device 1 of this embodiment is configured to include a compressor-expander unit 10, a heat storage unit 20, an air pressure supply pipe 30, and a control device 70. The compressor-expander unit 10 includes a motor (electric motor) 11, a compressor 12, a pressure storage tank 13, an expander 14, and a generator 15. The heat storage unit 20 includes a high-temperature side heat storage tank 21 containing a heat storage medium such as water, a low-temperature side heat storage tank 22, and heat exchangers 24 and 25.

[0020] The control device 70 has a function of controlling the valves V31-V33 and VL1-VL5 based on the pressure in the air pressure supply pipe 30 detected by a pressure sensor.

[0021] The CAES device 1 compresses air using a compressor 12 to a pressure exceeding a predetermined pressure P2 (e.g., about 0.6 MPa, P1<P2) that is set higher than an air operating pressure P1 (e.g., about 0.5 MPa) that drives air pressure equipment M1, and supplies compressed air that exceeds the predetermined pressure P2 to an expander 14 to generate electricity, while supplying compressed air at or below the predetermined pressure P2 to the air pressure equipment M1 via an air pressure supply pipe 30.

[0022] The predetermined pressure P2 may have a range. However, the lower limit of the predetermined pressure P2 is set higher than the air pressure use pressure P1, and the upper limit of the predetermined pressure P2 is set lower than the storage pressure P3. The storage pressure P3 is the upper limit of the internal tank pressure of the accumulator tank 13 according to specifications.

[0023] (1-1a) Compressor-Expander Unit The motor 11 is a prime mover that drives the compressor 12. The CAES device 1 of this embodiment is provided with a plurality of motors 11, and two motors 11a and 11b are shown in Fig. 1. The motors 11a and 11b are connected to the power transmission and distribution system 5 via an inverter 16.

[0024] The compressor 12 is a rotary machine driven by the motor 11 to compress air. The CAES system 1 of this embodiment is provided with a plurality of compressors 12, and Fig. 1 illustrates two compressors: a low-pressure compressor 12a and a high-pressure compressor 12b. The suction port of the compressor 12a is open to the atmosphere, and the discharge port of the compressor 12a is connected to the suction port of the compressor 12b via a pipe Lc1. The discharge port of the compressor 12b is connected to a heat exchanger 24 via a pipe Lc2, and is further connected to the accumulator tank 13 via the heat exchanger 24 and a piping system L.

[0025] The rotary shaft of the compressor 12a is mechanically connected to the output shaft of the motor 11a, and performs a low-stage compression stroke in which the compressor 12a sucks in and compresses the air. The rotary shaft of the compressor 12b is mechanically connected to the output shaft of the motor 11b, and performs a high-stage compression stroke in which the compressed air compressed by the compressor 12a is further compressed.

[0026] In the compressor-expander unit 10, multi-stage compression is performed by the compressors 12a and 12b, and the compressed air compressed by the compressors 12a and 12b is stored in the accumulator tank 13 via heat exchangers 24a and 24b. The CAES device 1 of this embodiment is provided with a plurality of accumulator tanks 13, and three accumulator tanks 13a to 13c are shown in FIG.

[0027] The piping system L described above includes a plurality of pipes L1-L6. Pipe L4 is connected to the compressed air outlet of heat exchanger 24, pipe L5 is connected to the compressed air inlet of heat exchanger 25, and pipe L6 connects pipes L4 and L5. Pipe L1 connects to accumulator tank 13a, pipe L2 connects to accumulator tank 13b, and pipe L3 connects to accumulator tank 13c, all to pipe L6. Through this piping system L, accumulator tanks 13a-13c are connected in parallel to heat exchangers 24 and 25.

[0028] The expander 14 is a rotary machine driven by compressed air stored in the accumulator tank 13. The CAES device 1 of this embodiment is provided with a plurality of expanders 14, and Fig. 1 illustrates two expanders: an expander 14a which is a high-pressure expander driven by compressed air from the accumulator tank 13, and an expander 14b which is a low-pressure expander driven by compressed air discharged from the expander 14a.

[0029] The suction port of the expander 14a is connected to the accumulator tank 13 via a heat exchanger 25a and a pipe Le1, and the discharge port of the expander 14a is connected to the suction port of the expander 14b via a heat exchanger 25b and a pipe Le2. The discharge port of the expander 14b is open to the atmosphere. The expander 14a performs the high-stage expansion stroke, and the expander 14b performs the low-stage expansion stroke.

[0030] In the compressor-expander unit 10, multi-stage expansion is performed by the expanders 14a and 14b, and the air discharged from the expander 14b is released into the atmosphere.

[0031] The generator 15 generates electricity by being driven by the expander 14. The CAES device 1 of this embodiment is provided with a plurality of generators 15, and Fig. 1 illustrates two generators: a generator 15a driven by the expander 14a and a generator 15b driven by the expander 14b.

[0032] The rotating shaft of the generator 15a is mechanically coupled to the output shaft of the expander 14a, and the rotating shaft of the generator 15b is mechanically coupled to the output shaft of the expander 14b. The generators 15a and 15b are connected to the power transmission and distribution system 5 via a power conditioner 17. The generators 15a and 15b are driven by the expanders 14a and 14b to generate electricity (regenerate power) and return the regenerated power to the power transmission and distribution system 5.

[0033] (1-1b) Heat Storage Unit In the heat storage unit 20, heat from the compressed air compressed by the compressors 12a, 12b is recovered by the heat exchangers 24a, 24b to the heat storage medium from the low-temperature side heat storage tank 22. The high-temperature heat storage medium heated by the heat exchangers 24a, 24b is stored in the high-temperature side heat storage tank 21. The high-temperature heat storage medium stored in the high-temperature side heat storage tank 21 releases heat to the compressed air in the heat exchangers 25a, 25b, and the low-temperature heat storage medium cooled by the heat exchangers 25a, 25b returns to the low-temperature side heat storage tank 22. The heat storage unit 20 is provided with pumps 28, 29, and the heat storage medium is transported by the pumps 28, 29 to circulate through the heat storage unit 20.

[0034] (1-1c) Air Pressure Supply Pipe The air pressure supply pipe 30 is a pipe that supplies compressed air from the CAES device 1 to air-driven pneumatic equipment M1. The pneumatic equipment M1 is, for example, an air-driven device used in a factory M, and may be driven by compressed air generated by a compressor X (not shown) that serves as an air pressure source installed in the factory and supplied from air piping within the factory. In this embodiment, the air pressure supply pipe 30 is, for example, connected in parallel with the compressor X to air piping within the factory, and can supply compressed air to the pneumatic equipment M1 together with or instead of the compressor X.

[0035] In this embodiment, the air pressure supply pipe 30 includes pipes 31-34 that connect the accumulator tank 13 and the pneumatic equipment M1 (air pipe of factory M). Pipe 31 connects to pipe L1 that connects to accumulator tank 13a, pipe 32 connects to pipe L2 that connects to accumulator tank 13b, and pipe 33 connects to pipe L3 that connects to accumulator tank 13c. Pipes 31-33 join together and are connected to pneumatic equipment M1 via pipe 34.

[0036] The pipe 31 is provided with a valve V31, the pipe 32 is provided with a valve V32, and the pipe 33 is provided with a valve V33. The pipe L4 and the pipe L5 are provided with a valve VL4 and a valve VL5, respectively.

[0037] Furthermore, a valve VL1 is provided in the above-mentioned pipe L1 (at a location farther from the accumulator tank 13a than the branching portion of the pipe 31). Similarly, a valve VL2 is provided in the pipe L2 (at a location farther from the accumulator tank 13b than the branching portion of the pipe 32), and a valve VL3 is provided in the pipe L3 (at a location farther from the accumulator tank 13c than the branching portion of the pipe 33).

[0038] These valves V31-V33 and VL1-VL5 are on-off valves that open and close the corresponding pipes, and can be controlled to open and close by the control device 70 by using, for example, an electromagnetically driven type.

[0039] Furthermore, a pressure sensor P31 is provided on the pipe 31, a pressure sensor P32 on the pipe 32, a pressure sensor P33 on the pipe 33, and a pressure sensor P34 on the pipe 34. Furthermore, the above-mentioned pipe Lc1 is provided with a pressure sensor Pc, and the pipe Le2 is provided with a pressure sensor Pe.

[0040] These pressure sensors P31-P34, Pc, and Pe are pressure sensors that detect the pressure of the corresponding pipes. The pressures detected by these pressure sensors P31-P34, Pc, and Pe can be used to monitor the pressure in each part of the system of the CAES device 1. Furthermore, the control device 70 can automatically control the opening and closing of valves V31-V33 and VL1-VL5 based on the pressures detected by these pressure sensors P31-P34, Pc, and Pe.

[0041] (1-1d) Control device The control device 70 is connected to the pressure sensors P31-P34, Pc, Pe, the power conditioner 4, and the power meter 71 of the factory M (which may be a computer in the control room of the factory M, etc.), and receives as input data such as the detected pressures of the pressure sensors P31-P34, Pc, Pe, the power generation amount from the power meter 72 that measures the power generation amount of the renewable energy power generation device, and the power demand of the factory M (power demand for the entire factory M, power demand for the pneumatic system).

[0042] The control device 70 is a computer that executes a control program and the like for the CAES device 1. The control device 70 is capable of outputting open / close commands to the valves V30-V34 and VL1-VL5, start commands / stop commands / rotation speed commands to the motors 11a and 11b and the pumps 28 and 29, rotation speed commands to the generators 15a and 15b, power generation output commands, and the like.

[0043] (1-2) Basic Operations The basic operations of the CAES device 1, specifically, the charging operation, the discharging operation, and the air pressure supply operation will be described in order.

[0044] (1-2a) Charging Operation During charging operation to generate and store compressed air, the CAES device 1 operates as follows. During charging operation, typically, the valves V31-V33 of the air pressure supply pipe 30 and the valve VL5 of the pipe L5 of the heat exchanger 25 are closed. Also, the valve VL4 of the pipe L4 of the heat exchanger 24 is open.

[0045] First, the motors 11a and 11b are driven by input power from the power transmission and distribution system 5. The motors 11a and 11b drive the compressors 12a and 12b, and two-stage compression is performed by the compressors 12a and 12b. The compressor 12a draws in atmospheric air through its intake port and performs a first-stage adiabatic compression. The compressor 12b draws in compressed air discharged from the outlet port of the compressor 12a and performs a second-stage adiabatic compression, discharging high-pressure, high-temperature compressed air. This high-temperature, high-pressure compressed air flows into the heat exchangers 24a and 24b and exchanges heat with the low-temperature heat storage medium supplied from the low-temperature side heat storage tank 22 to the heat exchangers 24a and 24b by the pump 29. This heat exchange raises the temperature of the low-temperature heat storage medium and stores it in the high-temperature side heat storage tank 21. Meanwhile, the compressed air cools down and flows into the pressure storage tank 13 where it is stored.

[0046] At this time, the compressed air is stored in the accumulator tanks 13a, 13b, and 13c in that order. That is, when the storage pressures of the accumulator tanks 13a, 13b, and 13c are all less than a predetermined storage pressure P3 (for example, about 1.2 MPa, where P1<P2<P3), the valves VL2 and VL3 of the accumulator tanks 13b and 13c are closed, and the valve VL1 of the accumulator tank 13a is opened, and compressed air is sent to the accumulator tank 13a.

[0047] Thereafter, when the pressure in the accumulator tank 13a detected by the pressure sensor P31 reaches the storage pressure P3, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, and the valve VL2 of the accumulator tank 13b is opened, switching the storage destination of the compressed air to the accumulator tank 13b.

[0048] When the pressure in the accumulator tank 13b detected by the pressure sensor P32 reaches the storage pressure P3, the valves VL1 and VL2 of the accumulator tanks 13a and 13b are closed, and the valve VL3 of the accumulator tank 13c is opened, switching the storage destination of the compressed air to the accumulator tank 13c.

[0049] When the pressure in the accumulator tank 13c detected by the pressure sensor P33 reaches the storage pressure P3, the valve VL3 is closed to stop storing compressed air in the accumulator tank 13c.

[0050] Through the above operation, part of the grid power is converted into the energy of the compressed air or heat storage medium and stored (charged) in the CAES device 1 .

[0051] (1-2b) Discharge Operation During discharge operation, in which compressed air is used to drive the generator and generate electricity, the CAES device 1 operates as follows. During discharge operation, typically, valves V31-V33 of the air pressure supply pipe 30 and valve VL4 of pipe L4 of heat exchanger 24b are closed. Also, valve VL5 of pipe L5 of heat exchanger 25a is open.

[0052] First, compressed air stored in the accumulator tank 13 is supplied to the heat exchanger 25a. At this time, the compressed air in the accumulator tank with the higher pressure is given priority. When all the accumulator tanks have the stored pressure P3, compressed air is supplied in a predetermined order (for example, the order of the accumulator tanks 13a, 13b, and 13c).

[0053] For example, when the pressure accumulator tanks 13a, 13b, and 13c are all at storage pressure P3, the valves VL2 and VL3 of the pressure accumulator tanks 13b and 13c are closed, the valve VL1 of the pressure accumulator tank 13a is opened, and the compressed air of the pressure accumulator tank 13a is sent to the heat exchanger 25a.

[0054] Thereafter, when the pressure in the accumulator tank 13a detected by the pressure sensor P31 drops to a predetermined pressure P2, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, the valve VL2 of the accumulator tank 13b is opened, and the source of compressed air to the heat exchanger 25 is switched to the accumulator tank 13b.

[0055] When the pressure in the accumulator tank 13b detected by the pressure sensor P32 drops to a predetermined pressure P2, the valves VL1 and VL2 of the accumulator tanks 13a and 13b are closed, the valve VL3 of the accumulator tank 13c is opened, and the source of compressed air to the heat exchanger 25 is switched to the accumulator tank 13c.

[0056] When the pressure in the accumulator tank 13c detected by the pressure sensor P33 drops to a predetermined pressure P2, the valve VL3 is closed to stop the supply of compressed air from the accumulator tank 13c to the heat exchanger 25.

[0057] The compressed air supplied from the pressure accumulator tank 13 flows into the heat exchanger 25a and exchanges heat with the high-temperature heat storage medium supplied from the high-temperature side heat storage tank 21 to the heat exchangers 25a, 25b by the pump 28. The high-temperature heat storage medium becomes cold through this heat exchange and is stored in the low-temperature side heat storage tank 22.

[0058] Meanwhile, the compressed air increases in temperature and is drawn into expanders 14a and 14b where it undergoes adiabatic expansion, driving generators 15a and 15b. The compressed air that has undergone adiabatic expansion in the first stage in expander 14a is drawn into expander 14b where it undergoes adiabatic expansion in the second stage, driving expander 14b. The low-temperature, low-pressure air that has undergone adiabatic expansion in expander 14b is released into the atmosphere from the discharge port of expander 14b.

[0059] When the expanders 14a and 14b are driven by the two-stage expansion of the compressed air, the expanders 14a and 14b drive the generators 15a and 15b, respectively, and the power generation output of the generators 15a and 15b is supplied to the transmission and distribution system 5 via the power conditioner 17.

[0060] Through the above operations, the compressed air energy stored in the CAES device 1 is regenerated and returned (discharged) to grid power.

[0061] (1-2c) Air Pressure Supply Operation During the air pressure supply operation for supplying compressed air at approximately the predetermined pressure P2 to the air pressure device M1, the CAES device 1 operates as follows.

[0062] During the air pressure supply operation, compressed air is supplied to the pneumatic device M1 in order from the accumulator tanks 13a-13c whose pressure has dropped to a predetermined pressure P2 (principally, equal to or greater than the air working pressure P1). Alternatively, if there are multiple accumulator tanks with a pressure of about the predetermined pressure P2, compressed air is supplied to the pneumatic device M1 in order from the accumulator tank with the lowest pressure.

[0063] For example, when the pressure in the accumulator tanks 13a and 13b is high and close to the storage pressure P3, and the pressure in the accumulator tank 13c is close to the predetermined pressure P2, first, the valve V33 on the pipe 33 of the air pressure supply pipe 30 corresponding to the accumulator tank 13c is opened, and the valve VL3 on the pipe L3 of the accumulator tank 13c is closed, and the compressed air stored in the accumulator tank 13c is supplied to the pneumatic equipment M1.

[0064] At that time, the valves V31 and V32 corresponding to the accumulator tanks 13a and 13b of the air pressure supply pipe 30 are closed. In this way, by switching the valves V31-V33 and VL1-VL3 between open and closed, compressed air at approximately a predetermined pressure P2 is supplied from the accumulator tanks 13a-13c to the pneumatic device M1 as needed.

[0065] In addition, when multiple accumulator tanks are provided as in the CAES device 1 of this embodiment, compressed air is typically supplied from any one of the accumulator tanks to the pneumatic device M1. For example, when compressed air is supplied from the accumulator tank 13c to the pneumatic device M1 and the pressure in the accumulator tank 13c falls below the air operating pressure P1, if the pressure in either the accumulator tank 13a or 13b is approximately a predetermined pressure P2, the source of compressed air supplied to the pneumatic device M1 is switched to the accumulator tank 13a or 13b by operating a valve.

[0066] (1-3) Operation Modes Table 1 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0067] The operation mode of the CAES device 1 will be described.

[0068] (1-3a) Operation Mode for Charging Only In the operation mode for charging only, the CAES device 1 performs only the charging operation described above, which generates and stores compressed air.

[0069] (1-3b) Operation Mode in which Only Discharge is Performed In the operation mode in which only discharge is performed, the CAES device 1 performs only the above-mentioned discharging operation in which the generator is driven by compressed air to generate electricity.

[0070] (1-3c) Operation Mode in Which Only Air Pressure is Supplied In the operation mode in which only air pressure is supplied, the CAES device 1 only performs the air pressure supply operation described above.

[0071] (1-3d) Operation mode in which charging and air pressure supply are performed simultaneously In the operation mode in which charging and air pressure supply are performed simultaneously, the CAES device 1 simultaneously performs the charging operation and the air pressure supply operation. At this time, different accumulator tanks are used for the charging operation and the air pressure supply operation.

[0072] For example, similarly to the charging operation described above, the valve VL5 of the pipe L5 of the heat exchanger 25a is closed, and the valve VL4 of the pipe L4 of the heat exchanger 24 is open. However, at this time, among the valves V31-V33 of the air pressure supply pipe 30, the valve (for example, V33) of the air pressure supply pipe connected to the tank with the lowest storage pressure is opened, and the rest are closed.

[0073] The motors 11a and 11b drive the compressors 12a and 12b, and the compressors 12a and 12b perform two-stage compression.

[0074] The compressed air is stored in the accumulator tank at a pressure lower than a predetermined storage pressure P3 (e.g., approximately 1.2 MPa, where P1<P2<P3). For example, the valves VL2 and VL3 of the accumulator tanks 13b and 13c are closed, and the valve VL1 of the accumulator tank 13a is opened, and compressed air is sent to the accumulator tank 13a.

[0075] Thereafter, when the pressure in the accumulator tank 13a detected by the pressure sensor P31 reaches the storage pressure P3, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, and the valve VL2 of the accumulator tank 13b is opened, switching the storage destination of the compressed air to the accumulator tank 13b.

[0076] At the same time, valve V33 of pipe 33 of air pressure supply pipe 30 corresponding to accumulator tank 13c is opened to supply compressed air stored in accumulator tank 13c to pneumatic device M1. At this time, valves V31 and V32 corresponding to accumulator tanks 13a and 13b of air pressure supply pipe 30 are closed. In this way, by switching the opening and closing of valves V31-V33 and VL1-VL3, compressed air at approximately a predetermined pressure P2 is supplied appropriately from accumulator tanks 13a-13c to pneumatic device M1.

[0077] By the above operation, discharge and air pressure supply operations are performed simultaneously.

[0078] (1-3e) Operation mode in which discharge and air pressure supply are performed simultaneously In the operation mode in which discharge and air pressure supply are performed simultaneously, the CAES device 1 performs the above-mentioned discharge operation and air pressure supply operation simultaneously. At this time, different accumulator tanks are used for the discharge operation and the air pressure supply operation.

[0079] For example, when the accumulator tank 13a is at a high pressure close to the storage pressure P3 and the accumulator tanks 13b and 13c are at a predetermined pressure P2, the valve VL4 of the pipe L4 of the heat exchanger 24b is closed. Also, the valve VL5 of the pipe L5 of the heat exchanger 25a is open, the valve VL1 of the pipe L1 connected to the accumulator tank 13a is open, and the other valves VL2 and VL3 are closed. However, at this time, among the valves V31-V33 of the air pressure supply pipe 30, the valve (for example, V33) of the air pressure supply pipe connected to the tank with the lowest storage pressure is opened, and the rest are closed.

[0080] First, compressed air from the accumulator tank 13a is sent to the heat exchanger 25a, where it exchanges heat with a high-temperature heat storage medium supplied from the high-temperature side heat storage tank 21 to the heat exchangers 25a, 25b by the pump 28, raising the temperature of the compressed air. The compressed air is then drawn into the expanders 14a, 14b, where it undergoes adiabatic expansion and drives the generators 15a, 15b. The power output of the generators 15a, 15b is supplied to the power transmission and distribution system 5 via the power conditioner 17.

[0081] When the pressure in the accumulator tank 13a detected by the pressure sensor P31 drops to a predetermined pressure P2, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, the valve VL2 of the accumulator tank 13b is opened, and the source of compressed air to the heat exchanger 25 is switched to the accumulator tank 13b.

[0082] At the same time, valve V33 of pipe 33 of air pressure supply pipe 30 corresponding to accumulator tank 13c is opened to supply compressed air stored in accumulator tank 13c to pneumatic device M1. At this time, valves V31 and V32 corresponding to accumulator tanks 13a and 13b of air pressure supply pipe 30 are closed. In this way, by switching the opening and closing of valves V31-V33 and VL1-VL3, compressed air at approximately a predetermined pressure P2 is supplied appropriately from accumulator tanks 13a-13c to pneumatic device M1.

[0083] For the air pressure supply, an accumulator tank 13c is used, which has an internal tank pressure that has dropped to a predetermined pressure P2 and is separate from the accumulator tanks 13a and 13b used in the discharging operation. The pressure in the accumulator tank 13c gradually drops due to the air pressure supply. When the pressure in the accumulator tank 13c drops to the air pressure usage pressure P1, the air pressure supply from the accumulator tank 13c can no longer be continued. Therefore, if the internal tank pressure of the other accumulator tanks 13a and 13b is higher than the predetermined pressure P2, the air pressure supply source is switched to the other accumulator tank (for example, accumulator tank 13b), and compressed air is supplied from accumulator tank 13b to the pneumatic device M1.

[0084] Furthermore, if there is no other accumulator tank other than the accumulator tank being used for the discharging operation whose internal pressure is equal to or greater than the predetermined pressure P2, the valve VL5 of the pipe L5 is closed, the discharging operation is terminated, the valve (V32 in this case) of the air pressure supply pipe 30 is opened, and the compressed air in the accumulator tank 13b is switched from the discharging operation to air pressure supply to the pneumatic device M1.

[0085] (1-4) Power Supply and Demand Adjustment The following describes the operation mode switching and power supply and demand adjustment of the CAES device 1. When switching modes, the operation / stop of each device and the opening and closing of valves are performed according to commands from the control device 70.

[0086] The control device 70 inputs the power generation amount of the renewable energy power generation device input from the power meter 72, the power consumption amount of the factory M input from the power meter 71, and the pressure of the air pressure supply pipe 30 detected by the pressure sensors P31-P34, and if the power generation amount (W72) of the renewable energy power generation device is less than the power consumption amount (W71) of the factory M and the pressure (P34) of the air pressure supply pipe 30 is equal to or greater than the air pressure usage pressure P1 and equal to or less than a predetermined pressure P2, it opens the valves V31-V33 as appropriate and supplies compressed air from the air pressure supply pipe 30 to the air pressure equipment M1.

[0087] For example, when only the accumulator tank 13c (pipe 33) among the accumulator tanks 13a-13c (pipes 31-33) is at an air pressure working pressure P1 or higher and a predetermined pressure P2 or lower, the valve V33 is opened and air pressure is supplied using the accumulator tank 13c.

[0088] (1-4a) When the amount of power generation exceeds the power demand When the amount of power generation (W72) of renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 exceeds the amount of power consumption (W71) of the factory M, and surplus power is generated, the CAES device 1 is operated in an operation mode for charging, and the surplus power is stored as compressed air.

[0089] At this time, if the operation request of the pneumatic equipment M1 is large and the amount of air pressure used is large, the CAES device 1 operates in an operation mode in which charging and air pressure supply are performed simultaneously. The operation request of the pneumatic equipment M1 is determined by the operator or the control device 70 based on monitoring data received from the factory M, and the operation mode is switched manually or automatically. By supplying the compressed air used by the pneumatic equipment M1 from the accumulator tank 13, the power demand for producing compressed air in the factory M is reduced, and the charging amount of the CAES device 1 increases by 10-20% of the power used in the factory M.

[0090] For example, when there is no request to operate the pneumatic equipment M1, such as when the production equipment of the factory M is out of service, the CAES device 1 operates in an operation mode in which only charging is performed. The compressed air stored in the CAES device 1 can be used not only for discharging but also as air pressure in the pneumatic equipment M1, so it is desirable to store a sufficient amount of compressed air during periods of low power demand.

[0091] For example, if the solar power generation device 2 generates a large amount of power and surplus power is generated during the day, the CAES device 1 can be operated in discharge mode at night to equalize the amount of power used during the day and night, and the reduction in power usage in the transmission and distribution system 5 during the day also reduces power costs.

[0092] (1-4b) When the amount of power generated is less than the power demand When the amount of power generated (W72) by renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 is less than the amount of power consumption (W71) of the factory M, operation in three operating modes is possible.

[0093] When there is a request to operate the pneumatic equipment M1, the CAES device 1 operates in an operation mode that only supplies air pressure, and supplies compressed air to the pneumatic equipment M1. Because there is no longer a demand for electricity to produce compressed air in the factory M, the amount of electricity generated by the renewable energy power generation device and the amount of electricity used by the factory M are balanced at a value that is about 10-20% lower than when compressed air is produced in the factory M, and the scale of power generation by the renewable energy power generation device can be reduced.

[0094] While performing air pressure supply operation, it is also possible to switch to an operation mode that performs both discharge and air pressure supply when the amount of power used in the factory M needs to be covered. In this embodiment, when there is a request to operate the pneumatic equipment M1, air pressure supply is given priority over discharge, thereby enabling highly efficient supply and demand adjustment with less energy loss.

[0095] Furthermore, when there is no request to operate the pneumatic device M1, the CAES device 1 operates in an operation mode in which only discharge is performed. The CAES device 1 operates in the operation mode in which discharge is performed, and generates electric power from the compressed air and supplies it to the power transmission and distribution system 5.

[0096] (1-4c) Determination of Operation Mode To perform the above-described operation, the control device 70 must determine the operation mode to be selected and automatically control the electrically powered devices including the valves V31-V33 and VL1-VL5. The operation mode is determined according to the flow shown in FIG.

[0097] FIG. 2 is a flowchart showing an example of control of the CAES apparatus according to the first embodiment of the present invention.

[0098] First, the control device 70 determines whether the current time is during the late night hours, for example, from 2:00 to 5:00 (step S101), and if the current time is during the late night hours, the control device 70 selects operation in the charging mode (step S105).

[0099] On the other hand, if the current time is not in the late night hours, the control device 70 determines whether the power consumption (W71) of the factory M exceeds (or is balanced with) the power generation amount (W72) of the renewable energy power generation device (step S102). This can be determined by the control device 70 from the power consumption of the factory M input from the wattmeter 71 and the power generation amount of the renewable energy power generation device input from the power conditioner 4.

[0100] If the power consumption (W71) of the factory M exceeds the power generation (W72) of the renewable energy power generation device, and if the power consumption (W71) of the factory M is balanced with the power generation (W72) of the renewable energy power generation device (YES in step S102), the control device 70 determines whether there is a request to operate the pneumatic equipment M1 (step S103).

[0101] If there is no request to operate the pneumatic device M1 (NO in step S103), the control device 70 selects operation in the discharge mode (step S107) and increases the power supply. At this time, the control device 70 opens the valve VL5, starts operation of the expander 14, and issues a power generation command to the power conditioner 17 to operate in an operation mode in which only discharge is performed.

[0102] On the other hand, if there is an air pressure request from the pneumatic device M1 (YES in step S103), the control device 70 selects operation in the air pressure supply mode (step S106) and reduces the amount of power used by the factory M. At this time, the control device 70 checks and compares the pressures (P31 to P33) of the accumulator tanks 13, opens the valve connecting the tank with the lowest pressure that is equal to or higher than the predetermined pressure P2 to the air pressure supply pipe 30, and supplies air pressure to the pneumatic device M1. The control device 70 also issues a stop command to the inverter 16, stops the operation of the compressors 12a and 12b, and operates in an operation mode in which only air pressure is supplied.

[0103] In this way, when there is a request to operate the pneumatic device M1, the control device 70 prioritizes operation in an operation mode in which only air pressure is supplied without performing a discharge operation.

[0104] On the other hand, if the power consumption (W71) of the factory M is lower than the power generation (W72) of the renewable energy power generation device (NO in step S102), the control device 70 determines whether there is a request to operate the pneumatic equipment M1 (step S104).

[0105] If there is no request to operate the pneumatic device M1 (NO in step S104), the control device 70 selects operation in a charging mode in which only charging operation is performed (step S109). At this time, the control device 70 opens the valve VL4, checks and compares the pressures (P31 to P33) of the accumulator tank 13, and opens the valve connected to the tank with the highest pressure that is equal to or lower than the pneumatic operating pressure P1, thereby performing charging.

[0106] On the other hand, if there is a request to operate the pneumatic device M1 (YES in step S104), the control device 70 selects operation in a mode in which charging and air pressure supply are performed (step S108). At this time, the control device 70 checks and compares the pressures (P31 to P33) of the accumulator tanks 13, opens the valve connecting the tank with the lowest pressure that is equal to or higher than the predetermined pressure P2 to the air pressure supply pipe 30, and supplies air pressure to the pneumatic device M1.

[0107] 3 and 4 show the changes in the pressure in the accumulator tank 13, the outputs of the compressor 12 and the expander 14, and the amount of electric power when the system is operated in this manner.

[0108] 3 and 4 are diagrams showing an example of the operation of the CAES apparatus according to the first embodiment of the present invention, in which Fig. 3 shows changes in the main time zone in the morning and Fig. 4 shows changes in the main time zone in the afternoon.

[0109] In the flow shown in Figure 2, the operating mode is switched by comparing the power generation amount (W72) of the renewable energy power generation device input from the power conditioner 4 with the power consumption amount (W71) of the factory M input from the wattmeter 71, but the switching may also be performed when the values ​​of W71 and W72 change beyond a predetermined threshold.

[0110] Alternatively, the switching may be performed when a predetermined time has elapsed since the values ​​of W71 and W72 have changed beyond a predetermined threshold.

[0111] Also, as shown in FIG. 3, it is possible to prioritize pre-programmed operation modes depending on the time of day, such as operating in charging mode during the late night hours from 2:00 to 5:00.

[0112] (1-5) Effects When introducing renewable energy power generation into a facility such as Factory M with the aim of achieving carbon neutrality, power leveling technology and energy supply and demand adjustment technology are required to make renewable energy the main power source.

[0113] For example, when using the solar power generation system 2, the CAES device 1 stores surplus energy by driving the compressor 12 and storing compressed air during the day when surplus power can be generated. However, during the day, the operating rate of production equipment in the factory M is high, and although the amount of power generated is large, the amount of power consumed by the factory M is also large. In order to increase the amount of energy stored during the day in order to effectively shift power to times when power generation is low (power leveling), it is reasonable not only to increase the amount of power generated by the renewable energy power generation system but also to curb the power consumption of the factory M, which is on the demand side.

[0114] In contrast, in this embodiment, compressed air is supplied from the CAES device 1 to the pneumatic equipment M1 used in the factory M as described above, so that the power demand of the factory M can be reduced by the amount of driving power of the compressor (not shown) for supplying air pressure in the factory M.

[0115] It is generally said that the power consumption of the pneumatic system for supplying compressed air used as a power source in a factory is about 10-20% of the factory's power consumption. Therefore, by utilizing the compressed air stored in the CAES device 1 for the pneumatic system of factory M, as in this embodiment, it is possible to secure the necessary air pressure supply amount while reducing the power demand for air pressure supply in factory M, and thus the power consumption of factory M can be significantly reduced.

[0116] Furthermore, unlike the discharge mode, which generates electricity using air that has been compressed to a high pressure, operation in the air pressure supply mode eliminates energy loss during expansion to generate electricity and allows for highly efficient use of the compressed air energy. Therefore, when there is a request to operate the pneumatic device M1, prioritizing air pressure supply over discharge enables highly efficient supply and demand adjustment with less energy loss.

[0117] In this way, the CAES device 1 can adjust the power demand of the factory M by supplying air pressure while charging and discharging, and can store surplus power, adjust power generation, and adjust supply and demand by demand response.

[0118] The CAES device 1 is expected to contribute to making renewable energy the main power source and reducing the amount of grid power used, thereby minimizing the amount of grid power used and minimizing the amount of fossil fuel-derived power used, and thus reducing carbon dioxide emissions caused by the use of fossil fuels.

[0119] Second Embodiment FIG. 5 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a second embodiment of the present invention.

[0120] In FIG. 5, elements that are the same as or correspond to those in the embodiment already described are given the same reference numerals as in the previously mentioned drawings, and descriptions thereof will be omitted as appropriate.

[0121] (2-1) CAES Apparatus The CAES apparatus 1 of this embodiment differs from the first embodiment in that the air pressure supply pipe 30 includes a pipe 35, the air pressure supply pipe 30 includes a pipe 36, and the CAES apparatus 1 is provided with a pipe 37.

[0122] The pipe 35 connects the pipe Le2, which connects the high-pressure stage expander 14a and the low-pressure stage expander 14b, to the pneumatic equipment M1. The pipe 36 connects the pipe Lc1, which connects the low-pressure stage compressor 12a and the high-pressure stage compressor 12b, to the pneumatic equipment M1.

[0123] Furthermore, the pipe 37 connects the pipe Lc1, which connects the low-pressure stage compressor 12a and the high-pressure stage compressor 12b, to the pipes L1-L3. The pipe 37 connects the accumulator tanks 13a-13c in parallel to the compressor 12a.

[0124] The piping 37 is configured to include piping 37a-37c that connects a piping Lc1 that connects the low-pressure stage compressor 12a and the high-pressure stage compressor 12b to the accumulator tank 13. The piping 37a is connected to a piping L1 that connects to the accumulator tank 13a, the piping 37b is connected to a piping L2 that connects to the accumulator tank 13b, and the piping 37c is connected to a piping L3 that connects to the accumulator tank 13c. The piping 37a-37c join together and are connected to the high-pressure stage compressor 12b via a piping 37d.

[0125] The pipe 37a is provided with a valve Vc1, the pipe 37b with a valve Vc2, and the pipe 37c with a valve V37c.

[0126] In this embodiment, the pipe 35 connects the pipe Le2 to the pipe 34. The pipe 36 connects the pipe Lc1 to the pipe 34. The pipe 35 is provided with a valve V35, the pipe Le2 (the portion of the pipe 35 on the side of the low-pressure stage expander 14b relative to the branching point of the pipe 35) is provided with a valve Ve, the pipe 36 is provided with a valve V36, and the pipe Lc1 (the portion of the pipe 36 on the side of the high-pressure stage compressor 12b relative to the branching point of the pipe 36) is provided with a valve Vc.

[0127] Valves V35, Ve, V36, Vc, Vc1, Vc2, and Vc2 are on-off valves similar to valve V31, etc. Pressure sensor Pe is provided in pipe Le2 at a location on the high-pressure stage expander 14a side relative to the branch point of pipe 35. Pressure sensor Pc is provided in pipe Lc1 at a location on the low-pressure stage compressor 12a side relative to the branch point of pipe 36.

[0128] Other hardware configurations of the CAES apparatus 1 of the second embodiment are similar to those of the first embodiment.

[0129] (2-2) Basic Operation The operation of the CAES device 1 of the second embodiment will be described. In this embodiment, the charging operation and discharging operation are the same as in the first embodiment, so here, the air pressure supply operation will be described.

[0130] In this embodiment, as in the first embodiment, air pressure can be supplied to the pneumatic device M1 sequentially from the accumulator tanks whose pressure has dropped to the predetermined pressure P2, and if there are multiple accumulator tanks with a pressure of about the predetermined pressure P2, compressed air can be supplied to the pneumatic device M1 preferentially from the accumulator tank with the lowest pressure.

[0131] Additionally, in this embodiment, the air pressure supply pipe 30 includes the pipe 35, so that the discharge operation and the air pressure supply operation can be performed simultaneously using compressed air supplied from the same accumulator tank.

[0132] For example, if all of the accumulator tanks 13a-13c are at a high pressure close to the storage pressure P3 and there is no accumulator tank whose pressure has been reduced to approximately the predetermined pressure P2, then valves V31-V33, Ve, and VL4 are closed, valves VL5 and V35 are opened, and one of valves VL1-VL3 is opened. This allows high-pressure compressed air from one of the accumulator tanks 13a-13c to be supplied to the first-stage expander 14a, and power can be generated and discharged by the generator 15a.

[0133] The compressed air that drives the expander 14a is reduced in pressure to approximately a predetermined pressure P2 by adiabatic expansion, discharged from the expander 14a, and supplied to the pneumatic device M1 through the valve V35 and the piping 35. In this embodiment, of the expanders 14a and 14b, only the expander 14a performs a discharge operation by single-stage expansion, and the compressed air reduced in pressure by single-stage expansion is also supplied to the pneumatic device M1.

[0134] Furthermore, in this embodiment, since the air pressure supply pipe 30 includes the pipe 36, for example, by closing the valve Vc and opening the valve V36 and operating only the compressor 12a out of the compressors 12a and 12b, the compressed air compressed by the compressor 12a can be flowed into the pipe 36 and supplied to the air pressure device M1, bypassing the accumulator tank 13.

[0135] (2-3) Operation Modes Table 2 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0136] In this embodiment, the operation modes in which only charging, discharging, or air pressure supply is performed, and the operation mode in which charging and air pressure supply are performed simultaneously are the same as those in the first embodiment. The difference from the first embodiment is that it is possible to implement an operation mode in which air pressure supply is performed through the pipe 35 while performing a discharging operation, and an operation mode in which air pressure supply is performed through the pipe 36 while performing a charging operation, etc.

[0137] (2-3a) Operation mode in which discharge and air pressure supply are performed simultaneously In the operation mode in which discharge and air pressure supply are performed simultaneously, the CAES device 1 simultaneously performs the above-mentioned discharge operation and air pressure supply operation. At this time, different accumulator tanks are used for the discharge operation and the air pressure supply operation.

[0138] For example, when the accumulator tank 13a is at a high pressure near the storage pressure P3 and the accumulator tanks 13b and 13c are at a predetermined pressure P2, compressed air is supplied to the expander 14a from the accumulator tank 13a, which has a higher internal tank pressure. For example, the accumulator tank 13c, whose internal tank pressure has dropped to the predetermined pressure P2, is used to supply air pressure. The pressure in the accumulator tank 13c gradually drops due to the air pressure supply. When the pressure in the accumulator tank 13c drops to the air usage pressure P1, the air pressure supply from the accumulator tank 13c can no longer be continued, so the compressed air supply source is switched and compressed air is supplied to the pneumatic device M1 from the accumulator tank 13b.

[0139] In addition, by closing valve Ve and opening valve V35, compressed air expanded and reduced in pressure by the first-stage expander 14a using compressed air from the same accumulator tank can be supplied to the pneumatic equipment M1 via piping 35. In this case, if the pressure after the first stage expansion detected by pressure sensor Pe does not decrease to approximately the predetermined pressure P2, valve Ve can be opened by adjusting the opening degree rather than fully closing it, thereby driving expander 14b to adjust the rotation speed of generator 15b to generate electricity and adjust the pressure of the compressed air for pneumatic supply.

[0140] (2-3b) Operation mode in which charging and air pressure supply are performed simultaneously In the operation mode in which only air pressure is supplied via the pipe 36, as described above, the valve Vc is closed and the valve V36 is opened, and only the first-stage compressor 12a of the compressors 12a and 12b is driven. As a result, compressed air compressed to approximately the predetermined pressure P2 by the compressor 12a can be supplied to the pneumatic device M1 via the pipe 36 without being stored in the accumulator tank 13, while the pressure is appropriately monitored by the pressure sensor Pc.

[0141] In an operation mode in which air pressure is supplied through the pipe 36 while charging is being performed, both valves Vc and V36 are opened and the compressors 12a and 12b are driven. As a result, a portion of the compressed air compressed to approximately a predetermined pressure P2 by the compressor 12a is flowed through the pipe 36 and supplied to the pneumatic device M1, and at the same time, the remaining compressed air discharged from the compressor 12a is further compressed by the compressor 12b and stored in the accumulator tank 13.

[0142] Furthermore, in an operation mode in which air pressure is supplied via the pipe 36 while charging is being performed, the valve Vc is closed, and one of the valves Vc1, Vc2, and Vc3 connected to the accumulator tanks 13a, 13b, and 13c that has not reached the air working pressure P1 is sequentially opened, and then the valve V36 is opened, and the compressors 12a and 12b are driven. As a result, compressed air compressed to approximately the predetermined pressure P2 by the compressor 12a is flowed into the pipe 36 and supplied to the pneumatic device M1, and at the same time, compressed air in the accumulator tank 13 that has not reached the air working pressure P1 can be further compressed by the compressor 12b and stored at high pressure in the accumulator tank 13.

[0143] (2-4) Power Supply and Demand Adjustment The following describes the operation mode switching and power supply and demand adjustment of the CAES device 1 of this embodiment. When switching modes, the operation / stop of each device and the opening and closing of valves are performed by commands from the control device 70.

[0144] (2-4a) When the amount of power generation exceeds the power demand When the amount of power generation (W72) of renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 exceeds the amount of power consumption (W71) of the factory M, and surplus power is generated, the CAES device 1 is operated in an operation mode for charging, and the surplus power is stored as compressed air.

[0145] At this time, if the operation demand of the pneumatic device M1 is large and the amount of air pressure used is large, the CAES device 1 operates in an operation mode in which charging and air pressure supply are performed simultaneously.

[0146] In an operating mode in which charging and air pressure supply are performed simultaneously, if a large amount of surplus electricity is generated, the compressors 12a and 12b need to be driven mainly for charging, and therefore air pressure is supplied to the air pressure equipment M1 from the pressure accumulator tank 13.

[0147] When the amount of surplus electricity generated is small, the supply of air pressure from the accumulator tank 13 to the pneumatic equipment M1 is stopped, valve V36 is opened and valve Vc is closed, compressed air at a predetermined pressure P2 discharged from compressor 12a is supplied to the pneumatic equipment M1, and one of valves Vc1, Vc2, and Vc3 connected to the accumulator tank 13 that has not reached the air operating pressure P1 is sequentially opened, and the compressed air in the accumulator tank 13 is compressed to high pressure by compressor 12b and charged.

[0148] (2-4b) When the amount of power generated is less than the power demand When the amount of power generated (W72) by renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 is less than the amount of power consumption (W71) of the factory M, operation in three operating modes is possible.

[0149] When there is no request to operate the pneumatic device M1, the CAES device 1 operates in an operation mode in which only discharge is performed. The CAES device 1 operates in the operation mode in which discharge is performed, and generates electricity from the compressed air and supplies it to the power transmission and distribution system 5.

[0150] When there is a request to operate the pneumatic device M1, the CAES device 1 is operated in an operation mode in which only air pressure is supplied, or in an operation mode in which discharge and air pressure are supplied simultaneously, and supplies compressed air to the pneumatic device M1.

[0151] Here, if there is a pressure accumulator tank whose pressure has been reduced to approximately a predetermined pressure P2, air pressure is supplied from the pressure accumulator tank at approximately the predetermined pressure P2 to the pneumatic equipment M1 without passing through the expander 14a, and compressed air is supplied to the expander 14a from another pressure accumulator tank close to the storage pressure P3, and while driving the generator 15a, air pressure reduced to the air usage pressure P1 is supplied to the pneumatic equipment M1 through the piping 35.

[0152] In this embodiment, if there is no accumulator tank whose pressure has been reduced to approximately the predetermined pressure P2, high-pressure compressed air close to the storage pressure P3 is supplied from one of the accumulator tanks 13a-13c to the expander 14a, and the expander 14a is driven to generate electricity, while the compressed air reduced in pressure by the expander 14a is supplied to the pneumatic equipment M1 via piping 35.

[0153] For example, when compressed air is supplied from the accumulator tank 13a, the pressure in the accumulator tank 13a is monitored by the pressure sensor P31, and when the pressure in the accumulator tank 13a drops to a predetermined pressure P2, the valve VL1 is closed and the valve V31 is opened, and the mode is switched to supply the compressed air, which has been reduced to the predetermined pressure P2, from the accumulator tank 13a to the pneumatic device M1 via the pipe 31 without passing through the expander 14a. When the pressure in this tank drops to the air usage pressure P1, the mode is switched back to supply compressed air from another accumulator tank 13b or 13c to the expander 14a, and supply of air is performed while driving the generator 15a.

[0154] (2-4c) Determination of Operation Mode To perform the above-described operation, the control device 70 must determine the operation mode to be selected and automatically control the electrically powered devices including the valves V31-V36, VL1-VL5, Vc1-Vc3, Ve, and Vc. The operation mode is determined according to the flow shown in FIG.

[0155] FIG. 6 is a flowchart showing an example of control of the CAES apparatus according to the second embodiment of the present invention.

[0156] The control flow diagram of Fig. 6 differs from the control flow diagram of the first embodiment of Fig. 2 in that step S201 is executed instead of step S106. In Fig. 6, the same steps as in Fig. 2 are denoted by the same reference numerals, and their description will be omitted.

[0157] When the power consumption (W71) of the factory M exceeds the power generation capacity (W72) of the renewable energy power generation device, or when the power consumption (W71) of the factory M is balanced with the power generation capacity (W72) of the renewable energy power generation device (YES in step S102), if there is a request to operate the pneumatic equipment M1 (YES in step S103), the control device 70 selects operation in a mode in which discharge and air pressure supply are performed simultaneously (step S201). At this time, the control device 70 supplies air pressure via the pipe 35 while driving the expander 14a to perform expansion and power generation.

[0158] In this way, even when there is a request to operate the pneumatic device M1, the air pressure can be supplied while performing the discharging operation without operating the compressor for supplying the air pressure.

[0159] 7 and 8 show the changes in the pressure in the accumulator tank 13, the outputs of the compressor 12 and the expander 14, and the amount of electric power when the system is operated in this manner.

[0160] 7 and 8 are diagrams showing an example of the operation of the CAES apparatus according to the second embodiment of the present invention, in which Fig. 7 shows changes in the main time slots in the morning and Fig. 8 shows changes in the main time slots in the afternoon.

[0161] In the flow shown in FIG. 6, the operation mode is switched by comparing the power generation amount (W72) of the renewable energy power generation device input from the power conditioner 4 with the power consumption amount (W71) of the factory M input from the power meter 71, but the operation mode may also be switched when the values ​​of W71 and W72 change beyond a predetermined threshold.

[0162] Alternatively, the switching may be performed when a predetermined time has elapsed since the values ​​of W71 and W72 have changed beyond a predetermined threshold.

[0163] Also, as shown in FIG. 7, it is possible to prioritize pre-programmed operation modes depending on the time period, for example, by giving priority to operation in charging mode during the late night hours from 2:00 to 5:00.

[0164] (2-5) Effects In this embodiment, the same effects as in the first embodiment can be obtained.

[0165] Additionally, in this embodiment, an operation mode can be performed in which the expander 14a is driven to perform expansion and generate electricity while supplying air pressure through the pipe 35. In this operation mode, when the pressure is reduced from the high-pressure accumulator tank 13 to the air pressure usage pressure P1 of the pneumatic device M1, the energy of the stored compressed air can be recovered by the expander 14a without loss.

[0166] Furthermore, an operation mode can be performed in which compressed air from the compressor 12a is supplied to the pneumatic equipment M1 through the piping 36. In the operation mode in which compressed air from the compressor 12a is supplied to the pneumatic equipment M1 through the piping 36, energy is required for the compressor 12a to compress the atmospheric air to approximately the predetermined pressure P2, but at the same time, high-pressure compressed air can be stored in the accumulator tank, enabling greater adjustment operation. Therefore, energy loss due to air pressure supply can be reduced, and system efficiency (power recovery efficiency) can be improved compared to the first embodiment.

[0167] As described above, according to this embodiment, it is possible to provide a CAES device that can use the compressed air stored in the accumulator tank 13 for both power generation and air pressure supply without reducing the pressure more than necessary, has high system efficiency including air pressure supply, and is capable of adjusting power supply and demand.

[0168] Third Embodiment FIG. 9 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a third embodiment of the present invention.

[0169] In FIG. 9, elements that are the same as or correspond to those in the embodiment already described are given the same reference numerals as in the previously described drawings, and descriptions thereof will be omitted as appropriate.

[0170] (3-1) CAES Device The CAES device 1 of this embodiment differs from the first embodiment in that it includes an air pressure supply unit 40 for supplying compressed air to the pneumatic device M1.

[0171] In this embodiment, the air pressure supply unit 40 includes an air pressure supply compressor 41 dedicated to supplying air pressure, different from the compressor 12, and pipes 42 and 43 that connect the air pressure supply compressor 41 to the air pressure supply pipe 30. The pipe 42 connects the air pressure supply compressor 41 to an air pressure tank 44, and the pipe 43 connects the air pressure tank 44 to the pipe 34 of the air pressure supply pipe 30. The pipe 43 is provided with a valve 45. The air pressure supply compressor 41 is driven by a motor (electric motor) 46 that is driven by grid power, like the compressors 12a and 12b.

[0172] In the air pressure supply unit 40, the air pressure supply compressor 41 draws in atmospheric air, compresses it to the air pressure operating pressure P1 of the air pressure equipment M1 or a predetermined pressure P2, sends the compressed air to the air pressure tank 44 via piping 42, and supplies the compressed air to the air pressure equipment M1 via piping 43 by opening and closing a valve 45.

[0173] The other hardware configuration of the CAES apparatus 1 of the third embodiment is similar to that of the first embodiment.

[0174] (3-2) Basic Operation The operation of the CAES device 1 of the third embodiment will be described. In this embodiment, the charging operation and discharging operation are the same as in the first embodiment, so here, the air pressure supply operation will be described.

[0175] In this embodiment, as in the first embodiment, air pressure can be supplied to the pneumatic device M1 sequentially from the accumulator tanks whose pressure has dropped to the predetermined pressure P2, and if there are multiple accumulator tanks with a pressure of about the predetermined pressure P2, compressed air can be supplied to the pneumatic device M1 preferentially from the accumulator tank with the lowest pressure.

[0176] Additionally, in this embodiment, air pressure can be supplied from the air pressure supply unit 40 in addition to air pressure supplied from the accumulator tank 13. When compressed air is supplied from the air pressure supply unit 40 to the pneumatic device M1, the valves V31-V33 are closed to block the air pressure supply from the accumulator tank 13, and the valve 45 of the air pressure supply unit 40 is opened to operate the air pressure supply compressor 41.

[0177] (3-3) Operation Modes Table 3 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0178] In this embodiment as well, the operation modes that can be performed in the first embodiment can be performed with the valve 45 closed and the air pressure supply compressor 41 stopped.

[0179] In addition, in this embodiment, an operation mode in which only air pressure is supplied by the air pressure supply compressor 41, an operation mode in which air pressure is supplied by the air pressure supply compressor 41 while a charging operation is being performed, and the like can be implemented.

[0180] (3-3a) Operation mode in which only air pressure is supplied In an operation mode in which only air pressure is supplied by the air pressure supply compressor 41, the compressors 12a, 12b and the expanders 14a, 14b are stopped and the valves V31-V33 are closed, and the valve 45 of the air pressure supply unit 40 is opened as described above to operate the air pressure supply compressor 41.

[0181] (3-3b) Operation mode in which charging and air pressure supply are performed simultaneously In an operation mode in which air pressure is supplied by the air pressure supply compressor 41 while charging is performed, by driving the compressors 12a, 12b and the air pressure supply compressor 41 with the valves V31-V33 closed, the charging operation of storing compressed air by the compressors 12a, 12b and the air pressure supply operation by the air pressure supply unit 40 can be performed simultaneously.

[0182] (3-4) Power Supply and Demand Adjustment The following describes the operation mode switching and power supply and demand adjustment of the CAES device 1 of this embodiment. When switching modes, the operation / stop of each device and the opening and closing of valves are performed by commands from the control device 70.

[0183] (3-4a) When the amount of power generation exceeds the power demand When the amount of power generation (W72) of renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 exceeds the amount of power consumption (W71) of the factory M, and surplus power is generated, the CAES device 1 is operated in an operation mode for charging, and the surplus power is stored as compressed air.

[0184] At this time, if the operation request of the pneumatic device M1 is large and the amount of air pressure used is large, the CAES device 1 operates in an operation mode in which charging and air pressure supply are performed simultaneously.

[0185] In an operating mode in which charging and air pressure supply are performed simultaneously, if a large amount of surplus electricity is generated, the compressors 12a and 12b need to be driven mainly for charging, and therefore air pressure is supplied to the air pressure equipment M1 by the air pressure supply unit 40.

[0186] When the amount of surplus power generated is small, there is no need to drive both compressors 12a and 12b, so the air pressure supply from the air pressure supply unit 40 is stopped and switched to air pressure supply from the accumulator tank 13. The method of air pressure supply from the accumulator tank 13 is as already described. When the air pressure supply from the accumulator tank 13 is sufficient, the air pressure supply unit 40 is stopped, thereby making it possible to reduce the power demand used by the air pressure supply unit 40.

[0187] (3-4b) When the amount of power generated is less than the power demand When the amount of power generated (W72) by renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 is less than the amount of power consumption (W71) of the factory M, operation in three operating modes is possible.

[0188] When there is a request to operate the pneumatic equipment M1, the CAES device 1 operates in an operation mode that only supplies air pressure, supplies compressed air to the pneumatic equipment M1, and stops operation of the air pressure supply compressor 41. Because there is no longer any demand for electricity to produce compressed air in the factory M, the amount of electricity generated by the renewable energy power generation device and the amount of electricity used by the factory M are balanced at a value that is about 10-20% lower than when compressed air is produced in the factory M, and the scale of power generation by the renewable energy power generation device can be reduced.

[0189] When there is no request to operate the pneumatic device M1, the CAES device 1 operates in an operation mode in which only discharge is performed. The CAES device 1 operates in the operation mode in which discharge is performed, and generates electricity from the stored compressed air and supplies it to the power transmission and distribution system 5.

[0190] (3-4c) Determination of Operation Mode To perform the above-described operation, the control device 70 must determine the operation mode to be selected and automatically control the electrically powered devices including the valves V31-V33, V45, and VL1-VL5. The operation mode is determined according to the flow chart shown in FIG. 2, as in the first embodiment.

[0191] 10 and 11 show the changes in the pressure in the accumulator tank 13, the outputs of the compressor 12 and the expander 14, and the amount of electric power when the system is operated in this manner.

[0192] 10 and 11 are diagrams showing an example of the operation of the CAES apparatus according to the third embodiment of the present invention, in which Fig. 10 shows changes in the main time slots in the morning and Fig. 11 shows changes in the main time slots in the afternoon.

[0193] In the flow shown in Figure 2, the operating mode is switched by comparing the power generation amount (W72) of the renewable energy power generation device input from the power conditioner 4 with the power consumption amount (W71) of the factory M input from the wattmeter 71, but the switching may also be performed when the values ​​of W71 and W72 change beyond a predetermined threshold.

[0194] Alternatively, the switching may be performed when a predetermined time has elapsed since the values ​​of W71 and W72 have changed beyond a predetermined threshold.

[0195] Also, as shown in FIG. 10, it is possible to operate the vehicle in a pre-programmed operating mode with priority depending on the time of day, for example, by giving priority to operation in the charging mode during the late night hours from 2:00 to 5:00.

[0196] (3-5) Effects In this embodiment, the same effects as in the first embodiment can be obtained.

[0197] Additionally, in this embodiment, an operation mode can be performed in which air pressure is supplied by the air pressure supply unit 40 whose specifications are optimized for air pressure supply, and by stopping this operation when adjusting supply and demand, it is possible to adjust by reducing the amount of power used in the factory M. Therefore, it is possible to improve system efficiency (power recovery efficiency).

[0198] Fourth Embodiment FIG. 12 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a fourth embodiment of the present invention.

[0199] In FIG. 12, elements that are the same as or correspond to those in the embodiment already described are given the same reference numerals as in the previously described drawings, and descriptions thereof will be omitted as appropriate.

[0200] (4-1) CAES Device The CAES device 1 of this embodiment differs from the first embodiment in that it includes a water supply pump 50 that is connected to the accumulator tank 13 and increases the tank pressure of the accumulator tank 13 .

[0201] Although FIG. 12 illustrates a configuration in which water is injected into the accumulator tank 13c by the water supply pump 50, the configuration may be such that water can be injected from the water supply pump 50 into at least one of the accumulator tanks 13a-31c.

[0202] A valve Vp is provided in a pipe 51 connecting the water supply pump 50 and the accumulator tank 13c.

[0203] The other hardware configuration of the CAES apparatus 1 of the fourth embodiment is similar to that of the first embodiment.

[0204] (4-2) Basic Operation The operation of the CAES device 1 of the fourth embodiment will be described.

[0205] In this embodiment, for example, when the pressure of the accumulator tank 13 to be used for air pressure supply is less than the predetermined pressure P2 or the air usage pressure P1 and air pressure cannot be supplied to the pneumatic equipment M1, water is injected into the accumulator tank 13 by the water supply pump 50 to increase the internal pressure of the accumulator tank 13, and the compressed air that is less than the predetermined pressure P2 can be pressurized and supplied to the pneumatic equipment M1.

[0206] Furthermore, for example, the pressure in the accumulator tank 13, which drops as air pressure is supplied, can be monitored by pressure sensors P31-P33, and when the pressure in the accumulator tank 13 drops to a predetermined pressure P2 or air pressure use pressure P1 (or a set value set with a margin around these values), the water supply pump 50 can be driven to maintain the pressure in the accumulator tank 13 at a pressure at which air pressure can be supplied, and the air pressure supply can be continued.

[0207] In this case, the predetermined pressure P2 or the air pressure operating pressure P1 (or a set value set with a margin around these values) can be used as a threshold value to feedback-control the driving and stopping of the water supply pump 50.

[0208] The air pressure supply from the accumulator tank 13 using the water supply pump 50 can be performed simultaneously with the charging operation and the discharging operation. For example, if the accumulator tanks 13a and 13b are at a high pressure of about storage pressure P3 while the accumulator tank 13c is below the predetermined pressure P2, the air pressure can be supplied from the accumulator tank 13c while discharging using the accumulator tank 13a and increasing the pressure with the water supply pump 50.

[0209] Furthermore, for example, when neither of the accumulator tanks 13b, 13c reaches the predetermined pressure P2, compressed air can be stored in the accumulator tank 13b, and the air pressure can be supplied from the accumulator tank 13c while being pressurized by the water supply pump 50.

[0210] In addition, if the pressure in the accumulator tank 13 is not sufficient for the discharge operation, the water supply pump 50 can be used to increase the pressure in the accumulator tank 13 to a level sufficient for the discharge operation.

[0211] The water injected into the accumulator tank 13 from the water supply pump 50 is appropriately drained from a drain pipe (not shown) when storing compressed air in the accumulator tank 13.

[0212] In addition to the air pressure supply operation and discharge operation using the water supply pump 50, the basic operations that can be performed in the first embodiment can also be performed in this embodiment.

[0213] (4-3) Operation Modes Table 3 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0214] In this embodiment as well, the operation modes that can be performed in the first embodiment can be performed with the valve Vp closed and the feedwater pump 50 stopped.

[0215] Additionally, in this embodiment, in the operation mode in which the air pressure supply operation or the discharge operation is performed, the pressure in the accumulator tank 13 can be increased by the water supply pump 50 .

[0216] (4-4) Power Supply and Demand Adjustment The operation mode switching and power supply and demand adjustment of the CAES device 1 of this embodiment are the same as those of the first embodiment.

[0217] (4-5) Effects In this embodiment, the same effects as in the first embodiment can be obtained.

[0218] Additionally, in this embodiment, as described above, even if the pressure in the accumulator tank 13 is lower than the pressure at which air pressure can be supplied, the air pressure can be supplied by increasing the pressure in the accumulator tank 13 with the water supply pump 50. In the operation mode in which the water supply pump 50 is driven, the power demand of the CAES 1 increases, but because the water supply pump 50 is a device dedicated to supplying air pressure to the pneumatic device M1, the specifications can be optimized for air pressure supply, and a decrease in system efficiency (power recovery efficiency) can be suppressed.

[0219] Fifth Embodiment FIG. 13 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a fifth embodiment of the present invention.

[0220] In FIG. 13, elements that are the same as or correspond to those in the embodiment already described are given the same reference numerals as in the previously mentioned drawings, and descriptions thereof will be omitted as appropriate.

[0221] (5-1) CAES Device The CAES device 1 of this embodiment differs from the first to fourth embodiments in that the accumulator tank 13 includes a low-pressure accumulator tank 13L and a high-pressure accumulator tank 13H.

[0222] The low-pressure accumulator tank 13L is connected to the outlet of the compressor 12a, which is a low-pressure compressor, via pipes LL and L30. The pipe LL connects the low-pressure accumulator tank 13L to the air pressure supply pipe 30, and the pipe L30 connects the air pressure supply pipe 30 to the outlet of the compressor 12a.

[0223] The high-pressure accumulator tank 13H is connected to the pipe L6 via the pipe LH. The pipe LH is provided with a valve VH. If there is only one high-pressure accumulator tank 13H, the valve VH is not necessarily required.

[0224] The low-pressure accumulator tank 13L stores compressed air compressed by the compressor 12a at a pressure equal to or higher than the air pressure operating pressure P1 and equal to or lower than a predetermined pressure P2, and the high-pressure accumulator tank 13H stores compressed air compressed by the high-pressure compressor 12b at a pressure higher than the predetermined pressure P2.

[0225] 13, only one low-pressure accumulator tank 13L and one high-pressure accumulator tank 13H are shown, but a plurality of each may be provided. The high-pressure accumulator tank 13H corresponds to the accumulator tank 13 (accumulator tanks 13a-13c) of the first embodiment.

[0226] Compressed air exceeding the predetermined pressure P2 of the high-pressure accumulator tank 13H is supplied to the expander 14, and compressed air having a pressure equal to or lower than the predetermined pressure P2 of the low-pressure accumulator tank 13L is supplied to the pneumatic device M1 via the pneumatic supply pipe 30. The pneumatic supply pipe 30 is provided with a valve V30.

[0227] In this embodiment, the pipes LL and LH are connected via a pipe L80 having a pressure reducing device 80, and the low-pressure accumulator tank 13L and the high-pressure accumulator tank 13H are connected via the pressure reducing device 80.

[0228] The pressure reducing device 80 is an element that reduces the pressure of compressed air exceeding a predetermined pressure P2 that flows from the high-pressure accumulator tank 13H side (high-pressure equipment E2 side) to the low-pressure accumulator tank 13L side (air pressure supply equipment E1 side) to a pressure equal to or lower than the predetermined pressure P2, and a pressure adjustment valve (pressure reducing valve) can be typically used. A closable type of pressure adjustment valve can also be used. Alternatively, an orifice, a throttle (a portion with a reduced flow area provided midway through the pipe L80), or other alternative means can also be used for the pressure reducing device 80.

[0229] A valve V40 is provided in the pipe Lc1 connecting the compressor 12a and the compressor 12b.

[0230] The other hardware configuration of the CAES apparatus 1 of the fifth embodiment is similar to that of the first embodiment.

[0231] The configuration of this embodiment allows existing air pressure supply equipment to be applied to the CAES system. For example, a factory M may already have an air pressure supply equipment E1 that stores compressed air compressed by a low-pressure compressor 12a in a low-pressure accumulator tank 13L and supplies the compressed air from the low-pressure accumulator tank 13L to air pressure equipment M1. In this case, the CAES device 1 of this embodiment can be constructed by utilizing the existing air pressure supply equipment E1 and additionally installing high-pressure equipment E2 (compressor 12b, heat storage unit 20, high-pressure accumulator tank 13H, expander 14, generator 15, etc.) downstream of a high-pressure compressor 12b to the air pressure supply equipment E1.

[0232] (5-2) Basic Operations The basic operations of the CAES device 1 of this embodiment, specifically, the charging operation, discharging operation, and air pressure supply operation will be described in order.

[0233] (5-2a) Charging Operation During charging operation to generate and store compressed air, the CAES device 1 operates as follows. During charging operation, the valve VL5 on the pipe L5 of the heat exchanger 25 is typically closed. Furthermore, the valves VL4 and VH on the pipes L4 and LH are open. The pressure in the high-pressure accumulator tank 13H is assumed to be less than the storage pressure P3. In this state, the motors 11a and 11b are driven by input power from the power transmission and distribution system 5, and the compressors 12a and 12b are driven, whereby compressed air is sent to the high-pressure accumulator tank 13H in the same manner as in the first embodiment.

[0234] Thereafter, when the pressure in the high-pressure accumulator tank 13H detected by a pressure sensor (not shown) reaches the storage pressure P3, the valve VH of the high-pressure accumulator tank 13H is closed and the motor 11b is stopped to stop storing compressed air in the high-pressure accumulator tank 13H. The motor 11a can continue to be driven to supply air pressure.

[0235] Through the above operations, part of the grid power is converted into the energy of compressed air or heat storage medium and stored (charged) in the CAES device 1, similarly to the first embodiment.

[0236] In this embodiment, a portion of the compressed air compressed by the compressor 12a, which is a low-pressure compressor, is sent to the low-pressure accumulator tank 13L and stored in the low-pressure accumulator tank 13L.

[0237] (5-2b) Discharge Operation During discharge operation, in which the generators 15a, 15b are driven by compressed air to generate electricity, the CAES device 1 operates as follows. During discharge operation, the valve VL4 of the pipe L4 of the heat exchanger 24 is typically closed. The pressure in the high-pressure accumulator tank 13H exceeds a predetermined pressure P2. In this state, by opening the valves VH, VL5 of the pipes LH, L5, the compressed air in the high-pressure accumulator tank 13H is drawn into the expanders 14a, 14b, where it is adiabatically expanded, and drives the expanders 14a, 14b to be released into the atmosphere.

[0238] When the expanders 14a and 14b are driven by the two-stage expansion of the compressed air, the expanders 14a and 14b drive the generators 15a and 15b, respectively, and the power generation output of the generators 15a and 15b is supplied to the transmission and distribution system 5 via the power conditioner 17.

[0239] By the above operation, the compressed air energy stored in the CAES device 1 is regenerated and returned (discharged) to grid power, similarly to the first embodiment.

[0240] (5-2c) Air Pressure Supply Operation In the CAES device 1 of this embodiment, the high-pressure equipment E2 downstream of the compressor 12b is not used for the air pressure supply operation. When the control device 70 opens the valve V30, compressed air compressed by the compressor 12a and stored in the low-pressure accumulator tank 13L at a pressure equal to or lower than a predetermined pressure P2 is supplied to the pneumatic device M1 via the air pressure supply piping 30. Furthermore, when the compressed air stored in the low-pressure accumulator tank 13L falls below the air operating pressure P1, the control device 70 opens the pressure reducing device 80 to reduce the pressure of the compressed air in the high-pressure accumulator tank 13H and supply it to the low-pressure accumulator tank 13L.

[0241] When the compressed air stored in the low-pressure accumulator tank 13L and the high-pressure accumulator tank 13H falls below the air operating pressure P1, the control device 70 operates the compressor 12a and supplies air pressure from the compressor 12a to the pneumatic equipment M1 via the piping L30.

[0242] (5-3) Operation Modes Table 5 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0243] The operation mode of the CAES device 1 of this embodiment will be described.

[0244] (5-3a) Operation mode in which only charging is performed In the operation mode in which only charging is performed, the CAES device 1 performs only the above-mentioned charging operation in which compressed air is generated by the compressors 12a and 12b and stored in the high-pressure accumulator tank 13H and the low-pressure accumulator tank 13L.

[0245] (5-3b) Operation Mode for Only Discharge In the operation mode for only discharge, the CAES device 1 performs only the above-mentioned discharge operation of driving the generators 15a and 15b with compressed air stored in the high-pressure accumulator tank 13H to generate electricity.

[0246] (5-3c) Operation mode for only air pressure supply In the operation mode for only air pressure supply, the CAES device 1 only supplies air pressure to the pneumatic device M1. There are two modes: air pressure supply mode A, in which compressed air from the low-pressure accumulator tank 13L is supplied to the pneumatic device M1, and air pressure supply mode B, in which the compressor 12a is operated to supply air from the compressor 12a to the pneumatic device M1 via L30.

[0247] (5-3d) Operation mode in which charging and air pressure supply are performed simultaneously In the operation mode in which charging and air pressure supply are performed simultaneously, the CAES device 1 simultaneously performs the charging operation and the air pressure supply operation. In this embodiment, the high-pressure accumulator tank 13H and the low-pressure accumulator tank 13L, which are independent of each other, are used, and the charging operation and the air pressure supply operation are performed in parallel.

[0248] (5-3e) Operation mode in which discharge and air pressure supply are performed simultaneously In the operation mode in which discharge and air pressure supply are performed simultaneously, the CAES device 1 can be operated in two ways: an operation in which the above-mentioned discharge operation and air pressure supply operation are performed simultaneously, and an operation in which, during the above-mentioned discharge operation, the valve V30 is opened and the compressed air in the high-pressure accumulator tank 13H is decompressed by the pressure reducing device 80 and supplied to the air pressure device M1.

[0249] However, in this embodiment, the compressed air compressed by the compressor 12a and stored in the low-pressure accumulator tank 13L at a pressure equal to or lower than a predetermined pressure P2 is not supplied to the pneumatic equipment M1, but the compressed air in the high-pressure accumulator tank 13H is used, and the charging operation and the air pressure supply operation are performed in parallel.

[0250] (5-4) Adjustment of Power Supply and Demand In the CAES device 1 of this embodiment, when the power generation amount (W72) of the renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 exceeds the power consumption amount (W71) of the factory M and surplus power is generated, the CAES device 1 is operated in an operation mode for charging.

[0251] Furthermore, when the amount of power generated (W72) by renewable energy power generation devices such as the solar power generation device 2 and the wind power generation device 3 connected to the power transmission and distribution system 5 is less than the amount of power consumed (W71) by the factory M, the CAES device 1 can operate in two operation modes. That is, when there is a request to operate the pneumatic device M1, the CAES device 1 operates in an operation mode in which only air pressure is supplied, and when there is no request to operate the pneumatic device M1, the CAES device 1 operates in an operation mode in which only discharge is performed.

[0252] When the power generation amount (W72) of the renewable energy power generation device such as the solar power generation device 2 and the wind power generation device 3 is less than the power consumption amount (W71) of the factory M, there is a request to operate the pneumatic equipment M1, and the pressure in the low-pressure accumulator tank 13L drops to the air usage pressure P1, the CAES device 1 operates in an operation mode that supplies the air pressure stored in the high-pressure accumulator tank 13H.

[0253] (5-4a) Determination of Operation Mode To perform the above-described operation, the control device 70 must determine the operation mode to be selected and automatically control the electrically powered devices including the valves V30, V40, VL4-VL5, and the pressure reducing device 80. The operation mode is determined according to the flow shown in FIG.

[0254] FIG. 14 is a flowchart showing an example of control of the CAES apparatus according to the fifth embodiment of the present invention.

[0255] First, as described in the explanation of "power supply and demand adjustment" in the first embodiment and the like, it is necessary to determine the magnitude relationship between the amount of power generated by the renewable energy power generation device and the amount of power used by the factory M.

[0256] The control device 70 determines whether the amount of power consumption (W71) of the factory M exceeds (or is balanced with) the amount of power generated by the renewable energy power generation device (W72) (step S501). This can be determined by the control device 70 from the amount of power consumption of the factory M input from the wattmeter 71 and the amount of power generated by the renewable energy power generation device input from the power conditioner 4.

[0257] If the power consumption (W71) of the factory M is lower than the power generation (W72) of the renewable energy power generation device (NO in step S501), the control device 70 determines whether there is a request to operate the pneumatic equipment M1 by checking whether the pressure (P31) of the low-pressure accumulator tank 13L is lower than the pneumatic operating pressure P1 (step S502).

[0258] If the pressure (P31) of the low-pressure accumulator tank 13L is not lower than the air pressure operating pressure P1 (NO in step S502), the control device 70 determines that there is no request to operate the air pressure equipment M1 and selects an operating mode for performing charging operation (step S503).

[0259] On the other hand, if the pressure (P31) of the low-pressure accumulator tank 13L is lower than the air usage pressure P1 (YES in step S502), the control device 70 determines that there is a request to operate the air pressure device M1 and selects operation in air pressure supply mode B, in which the compressor 12a is operated to supply air pressure from the compressor 12a via L30 (step S504).

[0260] On the other hand, if the power consumption (W71) of the factory M exceeds the power generation amount (W72) of the renewable energy power generation device, or if the power consumption (W71) of the factory M is balanced with the power generation amount (W72) of the renewable energy power generation device (YES in step S501), the control device 70 determines whether there is a request to operate the pneumatic equipment M1 by checking whether the pressure (P31) of the low-pressure accumulator tank 13L is lower than the air operating pressure P1 (step S505).

[0261] If the pressure (P31) of the low-pressure accumulator tank 13L is not lower than the air operating pressure P1 (NO in step S505), the control device 70 determines that there is no request to operate the air pressure device M1 and operates in an operating mode that only discharges air (step S506).

[0262] On the other hand, if the pressure (P31) of the low-pressure accumulator tank 13L is lower than the air operating pressure P1 (YES in step S505), the control device 70 determines that there is a request to operate the air equipment M1, and checks whether the pressure (P32) of the high-pressure accumulator tank 13H is higher than the pressure (P31) of the low-pressure accumulator tank 13L (step S507).

[0263] If the pressure (P32) of the high-pressure accumulator tank 13H exceeds the pressure (P31) of the low-pressure accumulator tank 13L (YES in step S507), the control device 70 opens the pressure reducing device 80, reduces the pressure of the compressed air stored in the high-pressure accumulator tank 13H and supplies it to the low-pressure accumulator tank 13L, and selects operation in air pressure supply mode A in which the compressed air in the low-pressure accumulator tank 13L is supplied to the pneumatic equipment M1 (step S510).

[0264] On the other hand, if the pressure (P32) of the high-pressure accumulator tank 13H is equal to or lower than the pressure (P31) of the low-pressure accumulator tank 13L (NO in step S507), the control device 70 selects operation in air pressure supply mode B, in which the compressor 12a is operated to supply air pressure from the compressor 12a (step S504).

[0265] As described above, in this embodiment, in the operation mode for charging, the operation request for the pneumatic device M1 is determined by comparing the pressure (P32) of the high-pressure accumulator tank 13H, the pressure (P31) of the low-pressure accumulator tank 13L, and the air usage pressure P1, and if there is a request for operation of the pneumatic device M1, the discharge operation is not performed, and priority is given to operation in an operation mode in which only air pressure is supplied. Also, if the compressed air in the low-pressure accumulator tank 13L is lower than the air usage pressure P1, compressed air compressed by the compressor 12a is supplied to the pneumatic device M1.

[0266] 15 and 16 show the changes in the pressure in the accumulator tank 13, the outputs of the compressor 12 and the expander 14, and the amount of electric power when the system is operated in this manner.

[0267] 15 and 16 are diagrams showing an example of the operation of the CAES apparatus according to the fifth embodiment of the present invention. Fig. 15 shows changes in the main time slots in the morning, and Fig. 16 shows changes in the main time slots in the afternoon.

[0268] In the flow shown in FIG. 14, the operation mode is switched by comparing the power generation amount (W72) of the renewable energy power generation device input from the power conditioner 4 with the power consumption amount (W71) of the factory M input from the power meter 71, but the operation mode may also be switched when the values ​​of W71 and W72 change beyond a predetermined threshold value.

[0269] Alternatively, the switching may be performed when a predetermined time has elapsed since the values ​​of W71 and W72 have changed beyond a predetermined threshold.

[0270] Also, as shown in FIG. 15, it is possible to operate the vehicle in a pre-programmed operation mode by giving priority to a certain time period, for example, by operating in the charging mode during the late night hours from 2:00 to 5:00.

[0271] (5-5) Effect By supplying compressed air used in the factory M from the CAES device 1, it is possible to adjust the power supply and demand of the factory and rationally level out the power, as in the first embodiment.

[0272] Furthermore, in this embodiment, compressed air from the compressor 12a can be supplied to the pneumatic device M1, as in the second embodiment. By supplying compressed air from the compressor 12a to the pneumatic device M1, the charge amount of the CAES device 1 decreases compared to when only charging is performed. However, since it is sufficient to compress the atmosphere to approximately the predetermined pressure P2 with the compressor 12a, the amount of energy used for supplying air pressure can be reduced, enabling highly efficient operation. Since energy loss due to air pressure supply can be reduced, the system efficiency (power recovery efficiency) of the CAES device 1 is improved.

[0273] This embodiment is similar to the second embodiment in that the compressed air compressed by the compressor 12a is supplied to the pneumatic equipment M1 by bypassing the compressor 12b, which is a high-pressure compressor, but differs from the second embodiment in that the compressed air compressed by the compressor 12a, which is a low-pressure compressor, can be stored in the low-pressure accumulator tank 13L.

[0274] In addition, the part that performs the air pressure supply operation (air pressure supply equipment E1) and the part that performs the charging operation and discharging operation (high-pressure equipment E2) are separated into an upstream and downstream stage, and each can be operated essentially independently.

[0275] Furthermore, in the fifth embodiment, if the factory M is equipped with an existing air pressure supply facility E1, the high-pressure facility E2 can be added to the existing air pressure supply facility E1 to ensure the functionality of the CAES, which has the great advantage of allowing the existing facility to be utilized without waste.

[0276] Sixth Embodiment FIG. 17 is a schematic diagram showing an example of the configuration of a CAES apparatus according to a seventh embodiment of the present invention.

[0277] In FIG. 17, elements that are the same as or correspond to those in the embodiment already described are given the same reference numerals as in the previously mentioned drawings, and descriptions thereof will be omitted as appropriate.

[0278] (6-1) CAES Device The CAES device 1 of this embodiment differs from the fifth embodiment in that a pipe 60 connecting the compressor 12a, which is a low-pressure compressor, to the pipe Lc2 is provided instead of the pipe L30 connecting the compressor 12a, which is a low-pressure compressor, to the air pressure supply pipe 30. In other words, the compressor 12a and the low-pressure accumulator tank 13L are not directly connected to each other.

[0279] The pipe 60 is provided with a valve V41, which is an electromagnetic valve that is opened and closed by the control device 70.

[0280] The other hardware configuration of the CAES apparatus 1 of the sixth embodiment is the same as that of the fifth embodiment.

[0281] This embodiment is common to the fifth embodiment in that it includes a high-pressure accumulator tank 13H and a low-pressure accumulator tank 13L as accumulator tanks, and that the low-pressure accumulator tank 13L is connected to the high-pressure accumulator tank 13H via a pressure reducing device 80 and is also connected to pneumatic equipment M1 via an air pressure supply pipe 30.

[0282] (6-2) Basic Operation In this embodiment, the high-pressure accumulator tank 13H stores compressed air that has been compressed by the compressor 12 (compressors 12a and 12b) to a pressure exceeding the predetermined pressure P2. The low-pressure accumulator tank 13L stores compressed air that has been stored in the high-pressure accumulator tank 13H or discharged from the compressor 12b and that has a pressure exceeding the predetermined pressure P2, after being depressurized by the pressure reducing device 80 to a pressure equal to or lower than the predetermined pressure P2.

[0283] Compressed air from the high-pressure accumulator tank 13H is supplied to the expander 14. Compressed air decompressed by the pressure reducing device 80, i.e., compressed air stored in the low-pressure accumulator tank 13L, or compressed air supplied from the high-pressure accumulator tank 13H or the compressor 12b via the pressure reducing device 80, is supplied to the pneumatic equipment M1 via the air pressure supply piping 30.

[0284] When the compressed air stored in the low-pressure accumulator tank 13L and the high-pressure accumulator tank 13H falls below the air pressure operating pressure P1, the control device 70 operates the compressor 12a, opens the valves V41, VL4 and the pressure reducing device 80, and supplies air pressure from the compressor 12a to the pneumatic equipment M1.

[0285] (6-3) Operation Modes Table 5 shows the operation of each device of the CAES device 1 in each operation mode in this embodiment.

[0286] The operating mode implemented in this embodiment differs from the fifth embodiment in that in air pressure supply mode B, the compressor 12a is operated and valves V41, VL4 and the pressure reducing device 80 are opened, so that air is supplied from the compressor 12a via L60 to the air pressure equipment M1.

[0287] (6-4) Power Supply and Demand Adjustment The operation mode switching and power supply and demand adjustment of the CAES device 1 of this embodiment are the same as those of the fifth embodiment.

[0288] (6-5) Effects In the present embodiment, compared to the fifth embodiment, all of the compressed air compressed by the compressor 12 (compressors 12a and 12b) passes through the heat exchanger 24, so that the thermal energy of the compressed air for air pressure supply purposes can also be recovered, and thermal efficiency can be improved.

[0289] 18 shows a schematic configuration diagram of an LAES device according to a seventh embodiment of the present invention. Similar to the CAES device 1 of the first embodiment, the LAES device 7 of the seventh embodiment is a device that levels the power (grid power) of a power transmission and distribution system 5 to which renewable energy power generation devices such as photovoltaic power generation devices 2 and wind power generation devices 3 are connected.

[0290] When the amount of power generated by the renewable energy power generation device is large compared to the amount of power used in the factory M, the LAES device 7 stores (charges) some of the grid power as energy in the form of liquid air obtained by liquefying compressed air. Furthermore, when the amount of power generated by the renewable energy power generation device is small compared to the amount of power used in the factory M, the LAES device 7 vaporizes the stored liquid air, generates power using the high-pressure compressed air, and returns (discharges) the power to the power transmission and distribution system 5. Furthermore, the LAES device 7 can supply the vaporized compressed air to pneumatic equipment M1 that is driven by air pressure in the factory M.

[0291] Only the differences in configuration from the first embodiment will be described below.

[0292] In the LAES device 7, the compressor-expander unit 10 and the liquefaction unit 90 are connected by a pipe L7, which branches off from a pipe L4 connected to the compressed air outlet of the heat exchanger 24.

[0293] (7-1a) The air compressed in multiple stages by the liquefaction unit compressors 12a and 12b passes through the heat exchangers 24a and 24b, and then through the pipe L7 and flows into the boost compressor 99. In the boost compressor 99, the pressure of the compressed air is increased for liquefaction, and the compressed air, which has now reached a higher pressure, releases heat to the surroundings and is cooled to approximately room temperature before flowing into the heat exchanger 91.

[0294] In the heat exchanger 91, the compressed air that has flowed in is cooled to about −160° C. and liquefied by exchanging heat with the already cooled heat storage medium inside the heat exchanger 91. The liquefied air passes through the pressure reducing valve V95, where it is further decompressed and cooled, and then stored in the pressure accumulator tank 98.

[0295] In the accumulator tank 98, the air decompressed by the pressure reducing valve V95 is separated into gas and liquid, and the gaseous air passes through the pressure reducing valve V94 and returns to the heat exchanger 91. In the heat exchanger 91, this gaseous air exchanges heat with compressed air flowing in from the boost compressor 99 to cool the compressed air, and then returns to the inlet of the boost compressor 99, where it is compressed again and liquefied.

[0296] A pressure sensor P91 is provided in the pipe from the accumulator tank 98 to the pump 92, and a pressure sensor P92 is provided in the pipe from the heat exchanger 91 to the valve VL9.

[0297] The pressure sensor P91 detects the pressure in the accumulator tank 98, and the pressure sensor P92 detects the supply pressure of compressed air from the liquefaction unit 90. These pressure sensors P91 and P92 make it possible to monitor the pressure in each part of the system of the liquefaction unit 90. Furthermore, based on the pressures detected by these pressure sensors P91 and P92, the liquefaction unit 90 can automatically control the opening and closing of the pressure reducing valves V93-V95 and the valves VL8 and VL9.

[0298] In the accumulator tank 98, the liquid air is stored at a pressure of about 1.5 to 2 MPa.

[0299] The control device 70 is connected to pressure sensors P31-P34, P91, P92, Pc, and Pe, a power conditioner 4, and a power meter 71 of factory M (which may be a computer in the control room of factory M, etc.), and inputs data such as the pressure detected by the pressure sensors P31-P34, P91, P92, Pc, and Pe, the power generation amount from a power meter 72 that measures the power generation amount of the renewable energy power generation device, and the power demand of factory M (power demand for the entire factory M, power demand for the pneumatic system).

[0300] The control device 70 is a computer that executes a control program and the like for the LAES device 7. The control device 70 is capable of outputting open / close commands to the valves V30-V34 and the pressure reducing valves V93-V95, VL1-VL5, VL8, and VL9, start commands / stop commands / rotation speed commands to the motors 11a and 11b, the boost compressor 99, and the pumps 28 and 29, and further, rotation speed commands and power generation output commands to the generators 15a and 15b.

[0301] (7-2) Basic Operations The basic operations of the LAES device 7, specifically, the charging operation, discharging operation, and air pressure supply operation will be described in order.

[0302] (7-2a) Charging Operation During charging operation to generate and store compressed air, the LAES device 7 operates as follows. During charging operation, typically, the valves V31-V33 of the air pressure supply pipe 30 and the valve VL5 of the pipe L5 of the heat exchanger 25 are closed. Also, the valve VL4 of the pipe L4 of the heat exchanger 24 is open.

[0303] First, the motors 11a and 11b are driven by input power from the power transmission and distribution system 5. The motors 11a and 11b drive the compressors 12a and 12b, and two-stage compression is performed by the compressors 12a and 12b. The compressor 12a draws in atmospheric air through its intake port and performs a first-stage adiabatic compression. The compressor 12b draws in compressed air discharged from the outlet port of the compressor 12a and performs a second-stage adiabatic compression, discharging high-pressure, high-temperature compressed air. This high-temperature, high-pressure compressed air flows into the heat exchangers 24a and 24b and exchanges heat with the low-temperature heat storage medium supplied from the low-temperature side heat storage tank 22 to the heat exchangers 24a and 24b by the pump 29. This heat exchange raises the temperature of the low-temperature heat storage medium and stores it in the high-temperature side heat storage tank 21. Meanwhile, the compressed air cools down and flows into the pressure storage tank 13 where it is stored.

[0304] At this time, the compressed air is stored in the accumulator tanks 13a, 13b, and 13c in that order. That is, when the storage pressures of the accumulator tanks 13a, 13b, and 13c are all less than a predetermined storage pressure P3 (for example, about 1.2 MPa, where P1<P2<P3), the valves VL2 and VL3 of the accumulator tanks 13b and 13c are closed, and the valve VL1 of the accumulator tank 13a is opened, and compressed air is sent to the accumulator tank 13a.

[0305] Thereafter, when the pressure in the accumulator tank 13a detected by the pressure sensor P31 reaches the storage pressure P3, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, and the valve VL2 of the accumulator tank 13b is opened, switching the storage destination of the compressed air to the accumulator tank 13b.

[0306] When the pressure in the accumulator tank 13b detected by the pressure sensor P32 reaches the storage pressure P3, the valves VL1 and VL2 of the accumulator tanks 13a and 13b are closed, and the valve VL3 of the accumulator tank 13c is opened, switching the storage destination of the compressed air to the accumulator tank 13c.

[0307] When the pressure in the accumulator tank 13c detected by the pressure sensor P33 reaches the storage pressure P3, the valve VL3 is closed and the valve VL8 is opened to supply compressed air to the boost compressor 99. The air compressed by the boost compressor 99 releases heat to the surroundings, is cooled to about room temperature, and then flows into the heat exchanger 91. The compressed air that has flowed into the heat exchanger 91 exchanges heat with the already cooled heat storage medium in the heat exchanger 91, where it is cooled to about -160°C and liquefied.

[0308] The air liquefied in the heat exchanger 91 passes through the pressure reducing valve V95, where it is further decompressed and cooled, and then stored in the accumulator tank 98. In the accumulator tank 98, the air decompressed by the pressure reducing valve V95 is separated into gas and liquid, and the gaseous air passes through the pressure reducing valve V94 and returns to the heat exchanger 91. In the heat exchanger 91, this gaseous air exchanges heat with compressed air flowing in from the boost compressor 99 to cool the compressed air, and then returns to the inlet of the boost compressor 99, where it is compressed and liquefied again.

[0309] The pressure in the accumulator tank 98 is detected by a pressure sensor P91 and controlled by pressure reducing valves V94 and V95 to maintain an appropriate storage pressure. In the accumulator tank 98, the temperature of the stored liquid air is adjusted by controlling the pressure.

[0310] Through the above operation, part of the grid power is converted into the energy of the compressed air, liquid air, and heat storage medium, and stored (charged) in the LAES device 7 .

[0311] (7-2b) Discharge Operation During discharge operation, in which compressed air is used to drive the generator and generate electricity, the LAES device 7 operates as follows. During discharge operation, typically, valves V31-V33 of the air pressure supply pipe 30, valves VL1-VL3 and VL8 connected to the accumulator tank 13, and valve VL4 of the pipe L4 of the heat exchanger 24b are closed. Also, valves VL5 and VL9 of the pipe L5 of the heat exchanger 25a are open.

[0312] First, liquid air stored in an accumulator tank 98 is flowed into a heat exchanger 91 by a pump 92 through a pressure reducing valve V93. The liquid air that flows into the heat exchanger 91 exchanges heat with the heat storage medium therein, rising in temperature to approximately room temperature, vaporizing, and flowing out as compressed air. This compressed air then passes through valves VL9 and VL5 and flows into the heat exchanger 25a via pipe L5. The compressed air passes through the heat exchangers 25a and 25b and is adiabatically expanded in the expanders 14a and 14b, thereby driving these expanders. The pressure of the compressed air flowing out of the heat exchanger 91 is detected by a pressure sensor P92 and controlled by the pressure reducing valve V93.

[0313] The compressed air that flows into the heat exchangers 25a and 25b exchanges heat with a high-temperature heat storage medium that is supplied to the heat exchangers 25a and 25b from the high-temperature side heat storage tank 21 by the pump 28. The high-temperature heat storage medium becomes cold through this heat exchange and is stored in the low-temperature side heat storage tank 22.

[0314] Meanwhile, the compressed air increases in temperature and is drawn into expanders 14a and 14b where it undergoes adiabatic expansion, driving generators 15a and 15b. The compressed air that has undergone adiabatic expansion in the first stage in expander 14a is drawn into expander 14b where it undergoes adiabatic expansion in the second stage, driving expander 14b. The low-temperature, low-pressure air that has undergone adiabatic expansion in expander 14b is released into the atmosphere from the discharge port of expander 14b.

[0315] When the expanders 14a and 14b are driven by the two-stage expansion of the compressed air, the expanders 14a and 14b drive the generators 15a and 15b, respectively, and the power generation output of the generators 15a and 15b is supplied to the transmission and distribution system 5 via the power conditioner 17.

[0316] When the liquid air stored in the accumulator tank 98 is used up, the valve VL9 is closed and the valves VL1 to VL3 connected to the accumulator tank 13 are sequentially opened, thereby supplying the compressed air stored in the accumulator tank 13 to the heat exchanger 25a. At this time, the compressed air from the accumulator tank with the higher pressure is given priority. When all of the accumulator tanks are at the stored pressure P3, the compressed air is supplied in a predetermined order (for example, the accumulator tanks 13a, 13b, and 13c).

[0317] For example, when the pressure accumulator tanks 13a, 13b, and 13c are all at storage pressure P3, the valves VL2 and VL3 of the pressure accumulator tanks 13b and 13c are closed, the valve VL1 of the pressure accumulator tank 13a is opened, and the compressed air of the pressure accumulator tank 13a is sent to the heat exchanger 25a.

[0318] Thereafter, when the pressure in the accumulator tank 13a detected by the pressure sensor P31 drops to a predetermined pressure P2, the valves VL1 and VL3 of the accumulator tanks 13a and 13c are closed, the valve VL2 of the accumulator tank 13b is opened, and the source of compressed air to the heat exchanger 25 is switched to the accumulator tank 13b.

[0319] When the pressure in the accumulator tank 13b detected by the pressure sensor P32 drops to a predetermined pressure P2, the valves VL1 and VL2 of the accumulator tanks 13a and 13b are closed, the valve VL3 of the accumulator tank 13c is opened, and the source of compressed air to the heat exchanger 25 is switched to the accumulator tank 13c.

[0320] When the pressure in the accumulator tank 13c detected by the pressure sensor P33 drops to a predetermined pressure P2, the valve VL3 is closed to stop the supply of compressed air from the accumulator tank 13c to the heat exchanger 25.

[0321] Through the above operation, the compressed air energy stored in the LAES device 7 is regenerated and returned (discharged) to grid power.

[0322] (7-2c) Air Pressure Supply Operation During the air pressure supply operation for supplying compressed air at approximately the predetermined pressure P2 to the air pressure device M1, the LAES device 7 operates as follows.

[0323] During the air pressure supply operation, compressed air is supplied to the pneumatic device M1 in order from the accumulator tanks 13a-13c whose pressure has dropped to a predetermined pressure P2 (principally, equal to or greater than the air working pressure P1). Alternatively, if there are multiple accumulator tanks with a pressure of about the predetermined pressure P2, compressed air is supplied to the pneumatic device M1 in order from the accumulator tank with the lowest pressure.

[0324] For example, when the pressure in the accumulator tanks 13a and 13b is high and close to the storage pressure P3, and the pressure in the accumulator tank 13c is close to the predetermined pressure P2, first, the valve V33 on the pipe 33 of the air pressure supply pipe 30 corresponding to the accumulator tank 13c is opened, and the valve VL3 on the pipe L3 of the accumulator tank 13c is closed, and the compressed air stored in the accumulator tank 13c is supplied to the pneumatic equipment M1.

[0325] At that time, the valves V31 and V32 corresponding to the accumulator tanks 13a and 13b of the air pressure supply pipe 30 are closed. In this way, by switching the valves V31-V33 and VL1-VL3 between open and closed, compressed air at approximately a predetermined pressure P2 is supplied from the accumulator tanks 13a-13c to the pneumatic device M1 as needed.

[0326] When the pressures in all of the accumulator tanks 13 fall below the air working pressure P1, valve VL9 is opened to supply the stored liquid air. At this time, liquid air stored in accumulator tank 98 is flowed into heat exchanger 91 by pump 92 through pressure reducing valve V93. The liquid air that flows into heat exchanger 91 exchanges heat with the heat storage medium in heat exchanger 91, raising its temperature to approximately room temperature and vaporizing. The naturalized compressed air passes through valve VL9 and flows into air pressure supply piping 30 via either valves V31-V33 or VL1-VL3, and is supplied to pneumatic equipment M1. The pressure of the compressed air flowing out of heat exchanger 91 is detected by pressure sensor P92 and controlled by pressure reducing valve V93.

[0327] In addition, when multiple accumulator tanks are provided like the LAES device 7 of this embodiment, compressed air is typically supplied to the pneumatic device M1 from any one of the accumulator tanks. For example, when compressed air is supplied to the pneumatic device M1 from the accumulator tank 13c and the pressure in the accumulator tank 13c falls below the air operating pressure P1, if the pressure in either the accumulator tank 13a or 13b is approximately a predetermined pressure P2, the source of compressed air for the pneumatic device M1 is switched to the accumulator tank 13a or 13b by operating a valve.

[0328] (7-3) Operation Modes Table 7 shows the operation of each device of the LAES device 7 in each operation mode in this embodiment.

[0329] Regarding the operation mode of the LAES device 7, only differences in the configuration from the first embodiment will be described.

[0330] (7-3a) Operation Mode in which Only Charging is Performed In the operation mode in which only charging is performed, only the charging operation described above is performed.

[0331] (7-3b) Operation Mode in which Only Discharge is Carried Out In the operation mode in which only discharge is carried out, only the above-mentioned discharging operation is carried out.

[0332] (7-3c) Operation Mode in Which Only Air Pressure is Supplied In the operation mode in which only air pressure is supplied, only the air pressure supply operation described above is performed.

[0333] (7-3d) Operation mode in which charging and air pressure supply are performed simultaneously In the operation mode in which charging and air pressure supply are performed simultaneously, the LAES device 7 simultaneously performs the charging operation and the air pressure supply operation. At this time, different accumulator tanks are used for the charging operation and the air pressure supply operation.

[0334] For example, as in the case of charging the accumulator tank 98 described above, while storing compressed air in a liquefied form, the valve (e.g., V33) of the air pressure supply pipe 30 that is connected to the tank with the lowest stored pressure is opened, and the rest are closed.

[0335] Compression is performed by the compressors 12 a and 12 b , and the compressed air is sent to the liquefaction unit 90 through the pipe L 7 and then stored in the accumulator tank 98 .

[0336] At the same time, valve V33 of pipe 33 of air pressure supply pipe 30 corresponding to accumulator tank 13c is opened, and compressed air stored in accumulator tank 13c is supplied to pneumatic device M1. At this time, valves V31 and V32 corresponding to accumulator tanks 13a and 13b of air pressure supply pipe 30 are controlled, and valves V31-V33 are switched between open and closed depending on the pressure of accumulator tank 13, and compressed air at approximately a predetermined pressure P2 is supplied from accumulator tanks 13a-13c to pneumatic device M1 as appropriate.

[0337] By the above operation, discharge and air pressure supply operations are performed simultaneously.

[0338] (7-3e) Operation mode in which discharge and air pressure supply are performed simultaneously In the operation mode in which discharge and air pressure supply are performed simultaneously, the LAES device 7 simultaneously performs the above-mentioned discharge operation and air pressure supply operation. At this time, different accumulator tanks are used for the discharge operation and the air pressure supply operation.

[0339] For example, liquid air in the accumulator tank 98 is vaporized and sent to the heat exchanger 25a, where it exchanges heat with a high-temperature heat storage medium supplied from the high-temperature side heat storage tank 21 to the heat exchangers 25a, 25b by the pump 28, raising the temperature of the compressed air, which is then drawn into the expanders 14a, 14b and adiabatically expanded to drive the generators 15a, 15b. The power output of the generators 15a, 15b is supplied to the power transmission and distribution system 5 via the power conditioner 17.

[0340] At the same time, the tank with the lowest pressure among the accumulator tanks 13, which stores compressed air at approximately the predetermined pressure P2, opens a valve (one of V31-V33) on the pipe connected to the air pressure supply pipe 30, and supplies the compressed air stored in the accumulator tank 13 to the pneumatic device M1. For example, when supplying air pressure from the accumulator tank 13c, the valves V31 and V32 corresponding to the accumulator tanks 13a and 13b on the air pressure supply pipe 30 are closed. In this way, by switching the opening and closing of the valves V31-V33, compressed air at approximately the predetermined pressure P2 is supplied appropriately from the accumulator tanks 13a-13c to the pneumatic device M1.

[0341] For the air pressure supply, the accumulator tanks whose internal pressure has dropped to a predetermined pressure P2 are used in sequence. The pressure in the accumulator tank 13 gradually drops due to the air pressure supply. When the pressure in the accumulator tank 13 drops to the air pressure use pressure P1, the air pressure supply from the accumulator tank 13 can no longer be continued, so compressed air is also supplied to the pneumatic device M1 by using the liquid air in the accumulator tank 98 that is being used for the discharging operation.

[0342] Furthermore, when it is expected that a large amount of compressed air will be used in the pneumatic device M1, the discharge operation is terminated, and an appropriate valve connected to the air pressure supply pipe 30 is selected and opened, and the liquid air in the accumulator tank 98 is switched from the discharge operation to air pressure supply to the pneumatic device M1.

[0343] (7-4) Power Supply and Demand Adjustment The operation mode switching of the LAES device 7 and the power supply and demand adjustment are performed in the same manner as in the first embodiment.

[0344] (7-5) Effects As with the CAES device of the first embodiment, it is possible to suppress the amount of electricity used in the factory M, and to adjust the electricity demand of the factory M by supplying air pressure while charging and discharging, thereby achieving supply and demand adjustment through storage of surplus electricity, regulated power generation, and demand response.

[0345] Furthermore, in the LAES device of this embodiment, the tank capacity and installation space for storing air can be significantly reduced compared to a CAES device, which means fewer installation restrictions and reduced equipment costs.

[0346] In the above-described embodiments 2 to 6, as in embodiment 1, an LAES device can be constructed by storing compressed air as liquid air using a liquefaction unit 90 (see embodiments to example 12 described in Figures 19 to 23).

[0347] (Variations) In each of the above embodiments, the renewable energy power generation device can be any device that utilizes energy that is constantly (or repeatedly) replenished by natural forces and that fluctuates irregularly, such as wind power, sunlight, solar heat, wave or tidal power, flowing water or tides, and geothermal heat.

[0348] Furthermore, the CAES device 1 or LAES device 7 of each embodiment can be applied even when the power demand of the factory M fluctuates greatly depending on the operating state of devices that consume large amounts of power within the factory M.

[0349] Furthermore, the power transmission and distribution system 5 is not limited to a general power transmission and distribution system of an electric power company, but may be a microgrid power system for a region or within a factory M.

[0350] Furthermore, in each embodiment, the number of accumulator tanks 13 is two or three, but the number of accumulator tanks 13 is not limited to this and may be any number.

[0351] In addition, it is also possible to provide a plurality of low-pressure accumulator tanks 13L and a plurality of high-pressure accumulator tanks 13H.

[0352] Furthermore, in the LAES device 7, the volume of the accumulator tank 13 may be significantly reduced. Because the pressure of the compressed air can be adjusted when the liquid air is vaporized, the accumulator tank can be configured with a volume that is just enough to serve as a buffer to absorb pressure fluctuations.

[0353] In addition, although the compressors 12a, 12b and the expanders 14a, 14b in each embodiment may be, for example, screw types, the types of these rotary machines are not limited thereto. The compressors 12a, 12b and the expanders 14a, 14b may be, for example, scroll types, turbo types, centrifugal types, or reciprocating types.

[0354] In addition, in each embodiment, the compressor 12 and the expander 14 are two-stage compression / two-stage expansion types, consisting of compressors 12a, 12b and expanders 14a, 14b, respectively. However, the compressor 12 and the expander 14 may be a single-stage compression / single-stage expansion type, or a three or more stage compression / expansion type, or may have different numbers of stages for compression and expansion.

[0355] Furthermore, in the LAES device 7, the second stage compressor can also be used as a booster compressor in the liquefaction unit 90.

[0356] Furthermore, although each drawing shows one compressor 12 and one expander 14, the number is not particularly limited, and the CAES device 1 may be provided with a plurality of compressors 12 and expanders 14. Also, there may be a configuration in which the number of motors and compressors differs (for example, when one motor drives a plurality of compressors), or a configuration in which the number of generators and expanders differs (for example, when a plurality of expanders drive a single generator).

[0357] 5 illustrates a configuration in which compressed air is extracted from the pipe Le2 connecting the high-pressure stage expander 14a and the low-pressure stage expander 14b of the multi-stage expansion type expander 14, but it is also possible to extract compressed air from an intermediate stage of a single-stage expander. The same applies to the examples of FIGS. 13 and 17, where compressed air can be extracted from an intermediate stage of a single-stage compressor.

[0358] In addition, in the seventh to twelfth embodiments, metal, quartz glass, and phase-change heat storage material are used as the low-temperature heat storage medium in the liquefaction unit 90. Metal and quartz glass have a large specific heat (heat capacity) and are suitable for low-temperature heat storage. In addition, concrete, gravel, etc. can also be used as the low-temperature heat storage medium.

[0359] Furthermore, although an organic material such as paraffin is used as the phase-change heat storage material, it is possible to select a material that changes phase at a temperature close to the phase-change temperature of air (solid phase to liquid phase), and other materials may also be used.

[0360] Furthermore, the method for liquefying compressed air is not limited to the above, and other methods may be used.

[0361] Furthermore, in embodiments 1 to 12, water (pressurized water) is used as the liquid high-temperature heat storage medium. Water has a larger specific heat (heat capacity) than other heat storage media such as silicone oil and synthetic oil, making it a suitable material for heat storage. It also has a high thermal conductivity, allowing it to transfer heat efficiently.

[0362] Furthermore, in the above-described first to sixth embodiments, it is also possible to use a liquid heat storage medium other than water, such as oil, but oil-based heat storage media tend to have high viscosity at low temperatures and require large pump power for transport, whereas water has low viscosity even at low temperatures and therefore has excellent transport properties, making it a preferred medium.

[0363] However, since water vaporizes at 100°C under normal pressure (atmospheric pressure), it is desirable to use it under pressure when storing high-temperature heat exceeding 100°C. For example, when pressurized to 1 MPa, it is possible to maintain the liquid phase up to approximately 180°C.

[0364] 1... CAES device (compressed air energy storage device), 2... solar power generation device (renewable energy power generation device), 3... wind power generation device (renewable energy power generation device), 7... LAES device (liquid air energy storage device), 11... electric motor, 12... compressor, 12a... compressor (low pressure compressor), 12b... compressor (high pressure compressor), 13... accumulator tank, 13L... low pressure accumulator tank, 13H... high pressure accumulator tank, 14... expander, 14a... expander (high pressure expander) expansion machine), 14b...expander (low-pressure expander), 15...generator, 30...air pressure supply piping, 31-36...piping, 41...air pressure supply compressor, 42, 43...piping, 50...water supply pump, 70...control device, 80...pressure reducing device, 90...liquefaction unit, Lc1, Le2...piping, M...factory (facility using air pressure equipment), M1...air pressure equipment, P1...air pressure used pressure, P2...predetermined pressure, P33-P34...pressure sensors, V31-V33...valves (on-off valves)

Claims

1. A compressed air energy storage device connected to pneumatic equipment driven by air pressure, comprising: an electric motor driven by electric power from a power transmission and distribution system to which a renewable energy power generation device is connected; a compressor driven by the electric motor; a pressure accumulator tank for storing compressed air compressed by the compressor; an expander driven by the compressed air stored in the pressure accumulator tank; a generator driven by the expander; piping through which the compressed air passes; a solenoid valve provided in the piping; a pressure sensor for detecting the pressure of the piping; and a control device for controlling the solenoid valve, wherein the piping includes an air pressure supply piping connected to the pneumatic equipment, and the control device controls the solenoid valve to drive the expander with compressed air exceeding a predetermined pressure, and controls the solenoid valve to supply compressed air at or below the predetermined pressure from the air pressure supply piping to the pneumatic equipment.

2. A compressed air energy storage device according to claim 1, wherein the control device controls the compressor and the solenoid valve to drive either the compressor or the expander.

3. A compressed air energy storage device as described in claim 2, wherein the control device controls the solenoid valve to supply the compressed air from the air pressure supply pipe to the pneumatic equipment when the amount of power generated by the renewable energy power generation device is less than the amount of power used by the facility that uses the pneumatic equipment and a request to operate the pneumatic equipment is received.

4. A compressed air energy storage device as claimed in claim 2, wherein the air pressure supply piping includes piping that connects the accumulator tank and the pneumatic equipment, and the control device controls the solenoid valve to supply compressed air stored in the accumulator tank to the pneumatic equipment.

5. A compressed air energy storage device as described in claim 2, wherein the expander comprises a high-pressure expander driven by compressed air from the pressure storage tank and a low-pressure expander driven by compressed air discharged from the high-pressure expander, the air pressure supply piping comprises piping connecting the high-pressure expander and the pneumatic equipment, and the control device controls the solenoid valve to drive the high-pressure expander with the compressed air, and supplies the compressed air discharged from the high-pressure expander to the pneumatic equipment.

6. A compressed air energy storage device as defined in claim 2, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, the air pressure supply piping comprises piping that connects the low-pressure compressor and the pneumatic equipment, and the control device drives the low-pressure compressor and controls the solenoid valve to supply the compressed air compressed by the low-pressure compressor to the pneumatic equipment.

7. A compressed air energy storage device as claimed in claim 2, further comprising an air supply compressor connected to the pneumatic equipment via the air supply piping, wherein the control device, when the amount of power generated by the renewable energy power generation device is greater than the amount of power used by the facility that uses the pneumatic equipment and a request to operate the pneumatic equipment is received, drives the air supply compressor and controls the solenoid valve to supply compressed air compressed by the air supply compressor to the pneumatic equipment.

8. A compressed air energy storage device according to claim 2, further comprising a water supply pump connected to the accumulator tank, wherein the control device drives the water supply pump to increase the tank pressure of the accumulator tank.

9. A compressed air energy storage device as defined in claim 2, wherein the accumulator tank includes a low-pressure accumulator tank for storing compressed air at or below a predetermined pressure, and a high-pressure accumulator tank for storing compressed air above the predetermined pressure, and the control device controls the solenoid valve to drive the expander with compressed air stored in the high-pressure accumulator tank, and controls the solenoid valve to supply the compressed air stored in the low-pressure accumulator tank from the air pressure supply piping to the pneumatic equipment.

10. A compressed air energy storage device as defined in claim 9, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, the low-pressure accumulator tank stores the compressed air compressed by the low-pressure compressor, and the high-pressure accumulator tank stores the compressed air compressed by the high-pressure compressor.

11. A compressed air energy storage device according to claim 10, wherein the low-pressure accumulator tank is connected to the high-pressure accumulator tank via a pressure reducing device, and the control device controls the pressure reducing device to reduce the pressure of the compressed air stored in the high-pressure accumulator tank and supply it to the low-pressure accumulator tank.

12. A compressed air energy storage device as described in claim 10, wherein the air pressure supply piping includes piping that connects the low-pressure compressor and the pneumatic equipment, and the control device controls the solenoid valve to supply compressed air compressed by the low-pressure compressor to the pneumatic equipment.

13. A compressed air energy storage device as claimed in claim 9, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, and further comprises a heat exchanger that recovers heat from the compressed air compressed by the high-pressure compressor, and piping that connects the low-pressure compressor and the heat exchanger, and the control device controls the solenoid valve to provide the compressed air from the low-pressure compressor to the pneumatic equipment via the piping that connects the low-pressure compressor and the heat exchanger.

14. An energy storage device connected to pneumatic equipment driven by air pressure, comprising: a compressor driven by power from a renewable energy power generation device; a heat exchanger that liquefies compressed air compressed by the compressor and vaporizes the liquefied compressed air; a pressure accumulator tank that stores the liquefied compressed air; an expander driven by the vaporized compressed air; piping through which the compressed air passes; a solenoid valve provided in the piping; a pressure sensor that detects the pressure of the piping; and a control device that controls the solenoid valve, wherein the piping includes an air pressure supply piping connected to the pneumatic equipment, and the control device controls the solenoid valve based on the pressure detected by the pressure sensor, thereby supplying the compressed air to the expander or the pneumatic equipment.

15. An energy storage device as claimed in claim 14, wherein the control device controls the solenoid valve to drive the expander with compressed air exceeding a predetermined pressure, and controls the solenoid valve to supply compressed air below the predetermined pressure from the air supply pipe to the pneumatic equipment.

16. An energy storage device according to claim 14, wherein the control device controls the compressor and the solenoid valve to drive either the compressor or the expander.

17. An energy storage device as described in claim 14, wherein the control device controls the solenoid valve to supply the compressed air from the air pressure supply pipe to the pneumatic equipment when the amount of power generated by the renewable energy power generation device is less than the amount of power consumed by the facility that uses the pneumatic equipment and a request to operate the pneumatic equipment is received.

18. An energy storage device as described in claim 14, wherein the air pressure supply piping includes piping that connects the accumulator tank and the pneumatic equipment, and the control device controls the solenoid valve to supply compressed air stored in the accumulator tank to the pneumatic equipment.

19. An energy storage device as described in claim 14, wherein the expander includes a high-pressure expander driven by compressed air from the pressure storage tank and a low-pressure expander driven by compressed air discharged from the high-pressure expander, the air pressure supply piping includes piping connecting the high-pressure expander and the pneumatic equipment, and the control device controls the solenoid valve to drive the high-pressure expander with the compressed air, and supplies the compressed air discharged from the high-pressure expander to the pneumatic equipment.

20. An energy storage device as defined in claim 14, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, the air pressure supply piping comprises piping that connects the low-pressure compressor and the air pressure equipment, and the control device drives the low-pressure compressor and controls the solenoid valve to supply the air compressed by the low-pressure compressor to the air pressure equipment.

21. An energy storage device as described in claim 14, further comprising an air pressure supply compressor connected to the pneumatic equipment via the air pressure supply piping, wherein the control device, when the amount of power generated by the renewable energy power generation device is greater than the amount of power used by the facility that uses the pneumatic equipment and a request to operate the pneumatic equipment is received, drives the air pressure supply compressor and controls the solenoid valve to supply compressed air compressed by the air pressure supply compressor to the pneumatic equipment.

22. An energy storage device as set forth in claim 14, wherein the accumulator tank includes a compressed air accumulator tank that stores compressed air compressed by the compressor, and further comprising a water supply pump connected to the compressed air accumulator tank, and the control device drives the water supply pump to increase the tank pressure of the compressed air accumulator tank.

23. An energy storage device as defined in claim 14, wherein the accumulator tank includes a compressed air accumulator tank that stores compressed air compressed by the compressor, and the compressed air accumulator tank includes a low-pressure accumulator tank that stores compressed air at or below a predetermined pressure, and a high-pressure accumulator tank that stores compressed air that exceeds the predetermined pressure, and the control device controls the solenoid valve to drive the expander with compressed air stored in the high-pressure accumulator tank, and controls the solenoid valve to supply compressed air stored in the low-pressure accumulator tank from the air pressure supply piping to the pneumatic equipment.

24. An energy storage device according to claim 23, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, the low-pressure accumulator tank stores the compressed air compressed by the low-pressure compressor, and the high-pressure accumulator tank stores the compressed air compressed by the high-pressure compressor.

25. An energy storage device according to claim 24, wherein the low-pressure accumulator tank is connected to the high-pressure accumulator tank via a pressure reducing device, and the control device controls the pressure reducing device to reduce the pressure of the compressed air stored in the high-pressure accumulator tank and supply it to the low-pressure accumulator tank.

26. An energy storage device according to claim 24, wherein the air pressure supply piping includes piping that connects the low-pressure compressor and the pneumatic equipment, and the control device controls the solenoid valve to supply compressed air compressed by the low-pressure compressor to the pneumatic equipment.

27. An energy storage device as defined in claim 23, wherein the compressor comprises a low-pressure compressor and a high-pressure compressor that compresses the compressed air compressed by the low-pressure compressor, and further comprises a heat exchanger that recovers heat from the compressed air compressed by the high-pressure compressor, and piping that connects the low-pressure compressor and the heat exchanger, and wherein the control device controls the solenoid valve to provide the compressed air from the low-pressure compressor to the pneumatic equipment via piping that connects the low-pressure compressor and the heat exchanger.

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