Compressed air energy storage device

Abstract

A compressed air energy storage device is provided with: a compressor driven by a motor; a pressure storage container for storing the compressed air compressed by the compressor; an expansion machine which is driven by the compressed air stored in the pressure storage container; a generator driven by the expander; and an air pressure supply pipe for supplying the compressed air to an air compressor driven by air pressure. An air compressor that compresses air to a pressure exceeding a predetermined pressure set to be higher than an air pressure using pressure for driving the air compressor by means of the compressor; a power generation unit for supplying compressed air having a pressure exceeding the prescribed pressure to the expander to generate power; compressed air having a pressure equal to or lower than the predetermined pressure is supplied to the air compressor through the air pressure supply pipe.

Description

Technical Field

[0001] The invention relates to a compressed air energy storage device. Background Art

[0002] Power generation using renewable energy sources such as wind power and solar power depends on weather conditions, so the amount of power generated can fluctuate and become unstable. Compressed Air Energy Storage (CAES) systems are known as systems that level out power output to account for these fluctuations.

[0003] A compressed air energy storage device (CAES device) using this CAES system converts electrical energy into compressed air and stores it in a pressure storage container. When electricity is needed, the compressed air drives the expander to operate the generator, generating electrical energy and leveling the output.

[0004] Among such CAES devices, Patent Document 1, for example, discloses a compressed air energy storage device that stores compressed air in containers of varying sizes in accordance with the cycle of power fluctuations. Patent Document 2 discloses a compressed air energy storage device that improves expander operating efficiency by exhausting compressed air at a lower pressure than a predetermined pressure without passing through the expander.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent No. 6368577

[0008] Patent Document 2: Japanese Patent Application Laid-Open No. 2017-8867 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] When renewable energy generation is used to achieve carbon neutrality in factories and business premises, power leveling technologies and energy supply and demand adjustment technologies are required to make renewable energy the primary power source. For example, when using solar power generation, during the daytime when there is surplus electricity, the CAES system operates the compressor to accumulate compressed air pressure, thereby storing energy. However, during the day, factories operate more production equipment, and although the power generation is high, the power consumption is also high. Therefore, there is room for improvement in order to efficiently store energy and effectively shift power to periods of low power generation (power leveling) while meeting the factory's daytime power needs.

[0011] The object of the present invention is to provide a compressed air energy storage device that can reasonably achieve power leveling by adjusting the power supply and demand of a factory.

[0012] Means for solving problems

[0013] In order to achieve the above-mentioned purpose, the present invention provides a compressed air energy storage device, which comprises: a compressor, which is driven by an electric motor; a pressure storage container, which stores compressed air compressed by the compressor; an expander, which is driven by the compressed air stored in the pressure storage container; a generator, which is driven by the expander; and an air pressure supply piping, which supplies the compressed air to an air compressor driven by air pressure, wherein the compressor is used to compress the air to a pressure exceeding a specified pressure set to be higher than the air pressure used to drive the air compressor, and the compressed air exceeding the specified pressure is supplied to the expander to generate electricity, and compressed air below the specified pressure is supplied to the air compressor via the air pressure supply piping.

[0014] Effects of the Invention

[0015] According to the present invention, power leveling can be rationally achieved by adjusting power supply and demand in a factory. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Schematic diagram of a CAES device according to a first embodiment of the present invention

[0017] Figure 2 Schematic diagram of a CAES device according to a second embodiment of the present invention

[0018] Figure 3 Schematic diagram of a CAES device according to a third embodiment of the present invention

[0019] Figure 4 Schematic diagram of a CAES device according to a fourth embodiment of the present invention

[0020] Figure 5 Schematic diagram of a CAES device according to a fifth embodiment of the present invention

[0021] Figure 6 Schematic diagram of a CAES device according to a sixth embodiment of the present invention

[0022] Figure 7 Schematic diagram of a CAES device according to a seventh embodiment of the present invention DETAILED DESCRIPTION

[0023] The following describes embodiments of the present invention using the accompanying drawings.

[0024] (First embodiment)

[0025] (1-1) CAES device

[0026] Figure 1It is a schematic diagram of the CAES device according to the first embodiment of the present invention. The CAES device 1 is a device for leveling the power (grid power) of the power transmission and distribution system 5 connected to renewable energy power generation devices such as a solar power generation device 2 and a wind power generation device 3. The renewable energy power generation device can supply power to the factory M, for example. When the power generation amount of the renewable energy power generation device is insufficient with respect to the power consumption of the factory M, the factory M supplements the insufficient part with grid power. The renewable energy power generation device is also connected to the power transmission and distribution system 5 via a power conditioner 4. When the power generation amount of the renewable energy power generation device is more than the power consumption of the factory M, the CAES device 1 stores a part of the grid power as the energy of compressed air (charging). In addition, when the power generation amount of the renewable energy power generation device is less than the power consumption of the factory M, the CAES device 1 generates power with the stored compressed air and returns power to the power transmission and distribution system (discharging). In addition, the CAES device 1 can supply compressed air to the pneumatic machine M1 driven by air pressure in the factory M.

[0027] The CAES device 1 of the present embodiment is configured to include a compressor-expander unit 10, a heat storage unit 20, and a pneumatic supply pipe 30. The compressor-expander unit 10 has a motor (electric motor) 11, a compressor 12, a pressure storage container 13, an expander 14, and a generator 15. The heat storage unit 20 has heat storage containers 21, 22 containing a heat storage medium such as water, and heat exchangers 24, 25.

[0028] The CAES device 1 compresses air with the compressor 12 to a pressure exceeding a specified pressure P2 (for example, about 0.6 MPa, P1 < P2) set higher than the pneumatic use pressure P1 (for example, about 0.5 MPa) for driving the pneumatic machine M1. The compressed air exceeding the specified pressure P2 is supplied to the expander 14 for power generation, and the compressed air below the specified pressure P2 is supplied to the pneumatic machine M1 via the pneumatic supply pipe 30. For the specified pressure P2, a range may also be set. However, the lower limit value of the specified pressure P2 is set higher than the pneumatic use pressure P1, and the upper limit value of the specified pressure P2 is set lower than the storage pressure P3. The storage pressure P3 is the upper limit value in terms of the container internal pressure of the pressure storage container 13.

[0029] (1-1a) Compressor-expander unit

[0030] The motor 11 is a prime mover for driving the compressor 12. There are multiple motors 11 in the CAES device 1 of the present embodiment. Figure 1 Two motors 11a, 11b are illustrated in the figure. The motors 11a, 11b are connected to the power transmission and distribution system 5 via a power conditioner 16.

[0031] The compressor 12 is a rotary machine that is driven by the electric motor 11 to compress air. The CAES device 1 of this embodiment includes a plurality of compressors 12. Figure 1 The diagram shows two compressors: compressor 12a, a low-pressure compressor, and compressor 12b, a high-pressure compressor. The intake port of compressor 12a opens to the atmosphere, and the discharge port of compressor 12a is connected to the intake port of compressor 12b via pipe Lc1. The discharge port of compressor 12b is connected to heat exchanger 24 via pipe Lc2, and is further connected to pressure accumulator 13 via pipe system L. The rotating shaft of compressor 12a is mechanically connected to the output shaft of electric motor 11a and is responsible for the low-pressure stage compression process, which draws in and compresses the atmosphere. The rotating shaft of compressor 12b is mechanically connected to the output shaft of electric motor 11a and is responsible for the high-pressure stage compression process, which further compresses the compressed air compressed by compressor 12a.

[0032] In the compressor-expander unit 10, the compressors 12a and 12b perform multi-stage compression, and the compressed air compressed by the compressors 12a and 12b is stored in the pressure storage container 13 via the heat exchanger 24. The CAES device 1 of this embodiment has a plurality of pressure storage containers 13. Figure 1 The figure shows three pressure accumulators 13a-13c. The piping system L comprises multiple 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 pressure accumulator 13a to pipe L6, pipe L2 connects pressure accumulator 13b to pipe L6, and pipe L3 connects pressure accumulator 13c to pipe L6. This piping system L connects pressure accumulators 13a-13c and heat exchangers 24 and 25 in parallel.

[0033] The expander 14 is a rotary machine driven by the compressed air stored in the pressure accumulator 13. The CAES device 1 of this embodiment includes a plurality of expanders 14. Figure 1 The diagram shows two expanders: expander 14a, a high-pressure expander driven by compressed air from the pressure accumulator 13, and expander 14b, a low-pressure expander driven by the compressed air discharged from the high-pressure expander 14a. The intake port of expander 14a is connected to the pressure accumulator 13 via a heat exchanger 25 and pipe Le1, while the discharge port of expander 14a is connected to the intake port of expander 14b via pipe Le2. The discharge port of expander 14b opens to the atmosphere. Expander 14a is responsible for the high-pressure expansion process, while expander 14b is responsible for the low-pressure expansion process. In the compressor-expander unit 10, multi-stage expansion is performed using the expanders 14a and 14b, and the air discharged from expander 14b is discharged into the atmosphere.

[0034] The generator 15 is driven by the expander 14 to generate electricity. The CAES device 1 of this embodiment includes a plurality of generators 15. Figure 1 The figure shows two generators: a generator 15a driven by an expander 14a, and a generator 15b driven by an expander 14b. The rotating shaft of generator 15a is mechanically connected to the output shaft of expander 14a, and the rotating shaft of generator 15b is mechanically connected to the output shaft of expander 14b. Generators 15a and 15b are connected to the power transmission and distribution system 5 via a power conditioner 17. Generators 15a and 15b are driven by expanders 14a and 14b to generate electricity (regenerate power), and the regenerated electricity is returned to the power transmission and distribution system 5.

[0035] (1-1b) Thermal storage unit

[0036] In thermal storage unit 20, heat from the compressed air compressed by compressor 12 is recovered by heat exchanger 24 into the thermal storage medium from thermal storage tank 22. The high-temperature thermal storage medium, heated by heat exchanger 24, is stored in thermal storage tank 21. The high-temperature thermal storage medium stored in thermal storage tank 21 releases heat to the compressed air by heat exchanger 25, and the low-temperature thermal storage medium, cooled by heat exchanger 25, is returned to thermal storage tank 22. Thermal storage unit 20 is equipped with pumps 28 and 29, and the thermal storage medium is transferred by pumps 28 and 29 and circulated within thermal storage unit 20.

[0037] (1-1c) Air pressure supply piping

[0038] The air supply piping 30 is a piping that supplies compressed air from the CAES system 1 to the air compressor M1, which is driven by air pressure. The air compressor M1 is, for example, an air-driven device used in the factory M. It is driven by compressed air generated by a compressor X (not shown) installed in the factory as an air pressure source and supplied from air piping within the factory. In this embodiment, the air supply piping 30 is connected to the air piping within the factory, for example, in parallel with the compressor X, and can supply compressed air to the air compressor M1 in conjunction with or in place of the compressor X.

[0039] In this embodiment, the air pressure supply piping 30 includes pipes 31-34 connecting the pressure accumulator 13 to the air compressor M1 (the air piping of the factory M). Pipe 31 is connected to pipe L1 connected to the pressure accumulator 13a, pipe 32 is connected to pipe L2 connected to the pressure accumulator 13b, and pipe 33 is connected to pipe L3 connected to the pressure accumulator 13c. Pipes 31-33 converge and are connected to the air compressor M1 via pipe 34.

[0040] Pipe 31 is provided with a valve V31, pipe 32 is provided with a valve V32, and pipe 33 is provided with a valve V33. Pipe L4 is provided with a valve VL4, and pipe L5 is provided with a valve VL5. Valve VL1 is provided in pipe L1 (at a location farther from the pressure accumulator 13a than the branching point of pipe 31). Similarly, valve VL2 is provided in pipe L2 (at a location farther from the pressure accumulator 13b than the branching point of pipe 32), and valve VL3 is provided in pipe L3 (at a location farther from the pressure accumulator 13c than the branching point of pipe 33). These valves V31-V33 and VL1-VL5 are on-off valves that open and close their corresponding pipes. For example, they are electromagnetically driven, allowing for opening and closing control by a control device (not shown). Manual on-off valves can also be used.

[0041] Furthermore, a pressure sensor S31 is provided in pipe 31, a pressure sensor S32 is provided in pipe 32, a pressure sensor S33 is provided in pipe 33, and a pressure sensor S34 is provided in pipe 34. Furthermore, a pressure sensor Sc is provided in pipe Lc1, and a pressure sensor Se is provided in pipe Le2. These pressure sensors S31-S34, Sc, and Se detect the pressures in their respective pipes. The pressures detected by these pressure sensors can be used to monitor the pressures in various parts of the CAES system 1. Furthermore, the pressures detected by these pressure sensors can be used by a control device (not shown) to automatically control the opening and closing of valves V31-V33 and VL1-VL5.

[0042] (1-2) Basic Actions

[0043] 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 sequence.

[0044] (1-2a) Charging action

[0045] During charging operation, which generates and stores compressed air, the CAES system 1 operates as follows. Typically, during charging operation, valves V31-V33 on the compressed air supply pipe 30 and valve VL5 on the pipe L5 of the heat exchanger 25 are closed. Furthermore, valve VL4 on the pipe L4 of the heat exchanger 24 is opened.

[0046] First, the electric motors 11a and 11b are driven by the input power from the power transmission and distribution system 5. The compressors 12a and 12b are driven by the electric motors 11a and 11b, and two-stage compression is performed by the compressors 12a and 12b. In the compressor 12a, atmospheric air is inhaled from the suction port and adiabatic compression of the first stage is performed. In the compressor 12b, the compressed air ejected from the ejection port of the compressor 12a is inhaled and adiabatic compression of the second stage is performed, and high-pressure and high-temperature compressed air is ejected. This high-temperature and high-pressure compressed air flows into the heat exchanger 24 and exchanges heat with the low-temperature heat storage medium supplied from the heat storage container 22 to the heat exchanger 24. Through this heat exchange, the low-temperature heat storage medium becomes high-temperature and is stored in the high-temperature side heat storage container 21. On the other hand, the temperature of the compressed air decreases and it flows into and is stored in the pressure accumulation container 13.

[0047] At this time, the compressed air is stored in the order of the pressure accumulation containers 13a, 13b, and 13c, for example. That is, when the pressure accumulation containers 13a, 13b, and 13c are all below the specified storage pressure P3 (for example, about 1.2 MPa, P1 < P2 < P3), the valves VL2 and VL3 of the pressure accumulation containers 13b and 13c are closed, the valve VL1 of the pressure accumulation container 13a is opened, and compressed air is supplied to the pressure accumulation container 13a. After that, after the pressure of the pressure accumulation container 13a detected by the pressure sensor S31 reaches the storage pressure P3, the valves VL1 and VL3 of the pressure accumulation containers 13a and 13c are closed, the valve VL2 of the pressure accumulation container 13b is opened, and the storage target of the compressed air is switched to the pressure accumulation container 13b. After the pressure of the pressure accumulation container 13b detected by the pressure sensor S32 reaches the storage pressure P3, the valves VL1 and VL2 of the pressure accumulation containers 13a and 13b are closed, the valve VL3 of the pressure accumulation container 13c is opened, and the storage target of the compressed air is switched to the pressure accumulation container 13c. After the pressure of the pressure accumulation container 13c detected by the pressure sensor S33 reaches the storage pressure P3, the valve VL3 is closed and the storage of compressed air in the pressure accumulation container 13c is stopped.

[0048] Through the above operations, a part of the grid power is converted into the energy of compressed air and the heat storage medium and stored in the CAES device 1 (charging).

[0049] (1-2b) Discharge operation

[0050] When performing the discharge operation of driving the generator with compressed air for power generation, the CAES device 1 operates as follows. During the discharge operation, typically, the valves V31-V33 of the compressed air supply pipe 30 and the valve VL4 of the pipe L4 of the heat exchanger 24 are closed. In addition, the valve VL5 of the pipe L5 of the heat exchanger 25 is opened.

[0051] First, compressed air stored in pressure accumulator 13 is supplied to heat exchanger 25. Priority is given to compressed air from the high-pressure pressure accumulator. If all pressure accumulators have a stored pressure of P3, compressed air is supplied in a predetermined order (e.g., the order of pressure accumulators 13a, 13b, and 13c). For example, if pressure accumulators 13a, 13b, and 13c all have a stored pressure of P3, valves VL2 and VL3 in pressure accumulators 13b and 13c are closed, and valve VL1 in pressure accumulator 13a is opened, allowing compressed air from pressure accumulator 13a to be supplied to heat exchanger 25. After the pressure of pressure accumulator 13a, as detected by pressure sensor S31, drops to a predetermined pressure of P2, valves VL1 and VL3 in pressure accumulators 13a and 13c are closed, and valve VL2 in pressure accumulator 13b is opened, switching the compressed air supply source to heat exchanger 25 to pressure accumulator 13b. After the pressure of the pressure accumulator 13b detected by the pressure sensor S32 drops to the predetermined pressure P2, the vessels VL1 and VL2 of the pressure accumulators 13a and 13b are closed, and the valve VL3 of the pressure accumulator 13c is opened, switching the compressed air supply source to the heat exchanger 25 to the pressure accumulator 13c. After the pressure of the pressure accumulator 13c detected by the pressure sensor S33 drops to the predetermined pressure P2, the valve VL3 is closed, stopping the supply of compressed air from the pressure accumulator 13c to the heat exchanger 25.

[0052] Compressed air supplied from pressure accumulator 13 flows into heat exchanger 25, where it exchanges heat with the high-temperature thermal storage medium supplied from thermal storage tank 21. This heat exchange cools the high-temperature thermal storage medium to a lower temperature and is stored in thermal storage tank 22 on the lower temperature side. Meanwhile, the compressed air's temperature rises and it is drawn into expander 14a, undergoing a first-stage adiabatic expansion, driving expander 14a. The compressed air adiabatically expanded in expander 14a is drawn into expander 14b, undergoing a second-stage adiabatic expansion, driving expander 14b. The low-temperature, low-pressure air adiabatically expanded in expander 14b is released into the atmosphere from the outlet of expander 14b. As expanders 14a and 14b are driven by the two-stage expansion of compressed air, generators 15a and 15b are driven by expanders 14a and 14b, respectively. The generated power output from generators 15a and 15b is supplied to the power transmission and distribution system 5 via power conditioner 17.

[0053] Through the above-mentioned operation, the compressed air energy stored in the CAES device 1 is regenerated and restored to grid power (discharge).

[0054] (1-2c) Air pressure supply action

[0055] During the air supply operation for supplying compressed air having a predetermined pressure P2 to the air compressor M1 , the CAES device 1 operates as follows.

[0056] During air supply operation, compressed air is supplied to the air compressor M1 sequentially, starting from the pressure accumulators 13a-13c whose pressure has dropped to a predetermined pressure P2 (in principle, at least the operating pressure P1). Alternatively, if there are multiple pressure accumulators with pressures around the predetermined pressure P2, compressed air is supplied to the air compressor M1 preferentially from the pressure accumulators with the lower pressures.

[0057] For example, if the pressure in pressure accumulators 13a and 13b is at a high pressure close to the stored pressure P3, and pressure accumulator 13c is at a pressure close to the specified pressure P2, valve V33 on pipe 33 of the air pressure supply pipe 30 corresponding to pressure accumulator 13c is first opened, and valve VL3 on pipe L3 of pressure accumulator 13c is closed, allowing compressed air stored in pressure accumulator 13c to be supplied to air compressor M1. At this time, valves V31 and V32 on the air pressure supply pipe 30 corresponding to pressure accumulators 13a and 13b are closed. In this way, by switching valves V31-V33 and VL1-VL3, compressed air at a pressure close to the specified pressure P2 is supplied from pressure accumulators 13a-13c to air compressor M1 as needed.

[0058] Furthermore, when the CAES system 1 of this embodiment generally includes multiple pressure accumulators, compressed air is typically supplied to the air compressor M1 from any one of the pressure accumulators. For example, if compressed air is supplied to the air compressor M1 from pressure accumulator 13c and the pressure in pressure accumulator 13c falls below the operating pressure P1, the compressed air supply source to the air compressor M1 is switched to either pressure accumulator 13a or 13b by valve operation if the pressure in either pressure accumulator 13a or 13b reaches approximately a predetermined pressure P2.

[0059] (1-3) Operation mode

[0060] The operation mode of the CAES device 1 will be described.

[0061] (1-3a) Charging-only operation mode

[0062] In the charging-only operation mode, the CAES device 1 performs only the above-mentioned charging operation of generating and storing compressed air.

[0063] (1-3b) Discharge-only operation mode

[0064] In the discharge-only operation mode, the CAES device 1 performs only the above-mentioned discharge operation of driving the generator with compressed air to generate electricity.

[0065] (1-3c) Operation mode with air pressure supply only

[0066] In the operation mode for performing only compressed air supply, the CAES device 1 performs only the compressed air supply operation.

[0067] (1-3d) Operation mode of simultaneous charging and air pressure supply

[0068] In the simultaneous charging and air pressure supply operation mode, the CAES device 1 performs the aforementioned charging and air pressure supply operations simultaneously. In this case, different pressure accumulators are used for the charging and air pressure supply operations.

[0069] For example, if pressure accumulator 13a is stored at a high pressure near pressure P3 and pressure accumulators 13b and 13c are stored at a predetermined pressure of approximately P2, the compressed air compressed by compressors 12a and 12b is stored in pressure accumulator 13b, whose internal pressure has been reduced to the predetermined pressure P2. Furthermore, pressure accumulator 13c, which is different from pressure accumulator 13b used for charging, is used for air pressure supply, and whose internal pressure has been reduced to the predetermined pressure P2. The pressure in pressure accumulator 13c gradually decreases as air pressure is supplied. When the pressure in pressure accumulator 13c drops to the operating pressure P1, air pressure supply from pressure accumulator 13c is no longer possible. Therefore, the compressed air supply source is switched, with compressed air supplied from pressure accumulator 13b to air compressor M1. Simultaneously, the storage destination for the compressed air compressed by compressors 12a and 12b is switched from pressure accumulator 13b to pressure accumulator 13c.

[0070] (1-3e) Operation mode of simultaneous discharge and air pressure supply

[0071] In the simultaneous discharge and air pressure supply operation mode, the CAES device 1 performs the discharge operation and the air pressure supply operation simultaneously. In this case, different pressure accumulators are used for the discharge operation and the air pressure supply operation.

[0072] For example, if pressure accumulator 13a is at a high pressure near the stored pressure P3, and pressure accumulators 13b and 13c are at a predetermined pressure of approximately P2, compressed air is supplied from pressure accumulator 13a, whose internal pressure is higher, to expanders 14a and 14b. Alternatively, for the compressed air supply, pressure accumulator 13c, whose internal pressure has been reduced to predetermined pressure P2, is used. The pressure in pressure accumulator 13c gradually decreases as the compressed air is supplied. When the pressure in pressure accumulator 13c drops to the operating pressure P1, the compressed air supply from pressure accumulator 13c is no longer possible. Therefore, the compressed air supply source is switched, with pressure accumulator 13b supplying compressed air to air compressor M1.

[0073] (1-4) Adjustment of power supply and demand

[0074] The operation mode switching and power supply and demand adjustment of the CAES device 1 will be described.

[0075] (1-4a) When power generation exceeds power demand

[0076] When the power generation from renewable energy generation devices such as the solar power generator 2 and wind power generator 3 connected to the power distribution system 5 exceeds the power consumption of the plant M, resulting in surplus power, the CAES system 1 operates in a charging mode, converting the surplus power into compressed air for storage. At this time, if the operating demand for the air compressor M1 is high and the air usage is high, the CAES system 1 operates in a mode that simultaneously charges and supplies air. The operating mode is switched manually or automatically based on the operator or control device's judgment regarding the operating demand for the air compressor M1, based on monitoring data received from the plant M. By supplying compressed air used in the air compressor M1 from the pressure accumulator 13, the power demand for compressed air generation in the plant M is reduced, and the CAES system 1 increases its charge capacity by 10-20% of the power used by the plant M.

[0077] For example, when factory M's production equipment is idle and there's no demand for the air compressor M1 to operate, the CAES system 1 can be operated in a charging-only mode. The compressed air stored in the CAES system 1 can be used not only for discharge but also for compressing the air compressor M1. Therefore, it's best to store sufficient compressed air during periods of low electricity demand. For example, if the solar power generation system 2 is generating high levels of power and surplus electricity is generated during the day, operating the CAES system 1 in discharge mode at night can level daytime electricity consumption and reduce electricity costs by reducing daytime electricity usage in the power transmission and distribution system 5.

[0078] (1-4b) When power generation is lower than power demand

[0079] When the power generation from renewable energy generation devices such as the solar power generator 2 and wind turbine 3 connected to the power distribution system 5 is less than the power consumption of the factory M, the CAES system 1 operates in a discharge mode, generating electricity from compressed air and supplying it to the power distribution system 5. At this time, if the operating demand for the air compressor M1 is high and the air usage is high, the CAES system 1 operates in a simultaneous discharge and air supply mode. By supplying compressed air used in the air compressor M1 from the pressure accumulator 13, the power demand for compressed air generation in the factory M can be reduced, allowing the CAES system 1 to increase its charge capacity by 10-20% of the power used by the factory M.

[0080] When there is no operation request for the air compressor M1 , the CAES device 1 operates in an operation mode for performing only discharge.

[0081] (1-4c) Electricity supply and demand balance

[0082] When the power generation from renewable energy generators, such as the solar power generator 2 and wind turbine 3 connected to the power transmission and distribution system 5, is equal to or approximately equal to the power consumption of the factory M, the CAES system 1 operates in an air compression-only mode, supplying compressed air to the air compressor M1. Because there is no power demand for compressed air generation within the factory M, the power generation from the renewable energy generators and the power consumption of the factory M are balanced at a value approximately 10-20% lower than when compressed air is generated within the factory M, enabling a reduction in the scale of power generation from the renewable energy generators.

[0083] (1-5) Effect

[0084] For example, when renewable energy generation is adopted in a setting such as a factory M in order to achieve carbon neutrality, power leveling technology and energy supply and demand adjustment technology are required to make renewable energy the main power source. For example, when using a solar power generation device 2, during the day when surplus power may be generated, the compressor 12 is driven in the CAES device 1 to store compressed air, thereby storing surplus energy. However, the operating rate of the generation equipment of the factory M is high during the day, and although the power generation is large, the power consumption of the factory M is also large. In order to effectively shift power to the period of low power generation (power leveling) and increase the amount of energy stored during the day, it is reasonable not only to increase the power generation of the renewable energy power generation device, but also to suppress the power consumption of the demand side, that is, the factory M.

[0085] In this regard, in this embodiment, by supplying compressed air from the CAES unit 1 to the air compressor M1 used in the factory M as described above, the power demand of the factory M can be reduced by an amount equivalent to the driving power of the compressor (not shown) used to supply compressed air in the factory M. It is generally believed that the power consumption of the air compressor system used to supply compressed air as a power source in a factory accounts for approximately 10-20% of the factory's total power consumption. Therefore, by using the compressed air stored in the CAES unit 1 for the air compressor system of the factory M, as in this embodiment, the power demand for air supply in the factory M can be reduced while ensuring the necessary air supply volume, significantly reducing the power consumption of the factory M.

[0086] In this way, the CAES system 1 can adjust the power demand of the factory M through air pressure supply during both charging and discharging, and adjust supply and demand by storing excess power, adjusting power generation, and responding to demand. The CAES system 1 can achieve more rational power leveling by adjusting the power supply and demand of the factory M, for example by suppressing the power demand of the factory M during the day. This can contribute to reducing grid power usage by making renewable energy the primary power source.

[0087] (Second embodiment)

[0088] Figure 2It is a schematic diagram of a CAES device according to a second embodiment of the present invention. Figure 2 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0089] (2-1) CAES device

[0090] The CAES device 1 of this embodiment is different from the first embodiment in that the compressed air supply piping 30 is configured to include a piping 35 that connects the piping Le2 connecting the low-pressure expander 14a and the high-pressure expander 14b to the air compressor M1. In this embodiment, the piping 35 connects the piping Le2 and 34. In addition, a valve V35 is provided in the piping 35, and a valve Ve is provided in the piping Le2 (a portion located on the low-pressure expander 14b side relative to the branch portion of the piping 35). Valves V35 and Ve are on-off valves similar to valve V31 and the like. The pressure sensor Se is provided at a portion on the high-pressure expander 14a side relative to the branch portion of the piping 35 in the piping Le2. The hardware structure of the other CAES device 1 of the second embodiment is the same as that of the first embodiment.

[0091] (2-2) Basic Actions

[0092] The operation of the CAES device 1 according to the second embodiment will be described. In this embodiment, the charging and discharging operations are the same as those in the first embodiment, so the air pressure supply operation will be described here.

[0093] In this embodiment, as in the first embodiment, compressed air can be supplied to the air compressor M1 sequentially starting from the pressure accumulator container whose pressure has been reduced to the prescribed pressure P2, and when there are multiple pressure accumulator containers with the prescribed pressure P2, compressed air can be supplied to the air compressor M1 preferentially from the pressure accumulator container with the lower pressure.

[0094] Furthermore, in this embodiment, by including piping 35 in the air pressure supply piping 30, it is possible to simultaneously perform discharge and air pressure supply operations using compressed air supplied from the same pressure accumulator. For example, if all pressure accumulators 13a-13c are high pressure, close to the stored pressure P3, and no pressure accumulator has been reduced to the predetermined pressure P2, valves V31-V33, Ve, and VL4 can be closed, while valves VL5 and V35 are open. This allows high-pressure compressed air to be supplied from one of the pressure accumulators 13a-13c to the first-stage expander 14a, generating electricity and discharging the compressed air using the generator 15a. The compressed air driving the expander 14a undergoes adiabatic expansion, reducing its pressure to the predetermined pressure P2. The compressed air is then discharged from the expander 14a and supplied to the air compressor M1 via valve V35 and piping 35. In the present embodiment, only the expander 14a of the expanders 14a and 14b performs a discharge operation by a single-stage expansion, and simultaneously supplies the compressed air whose pressure is reduced by the single-stage expansion to the air compressor M1.

[0095] (2-3) Operation mode

[0096] In this embodiment, the operation mode of performing only one of charging, discharging, and air pressure supply, and the operation mode of performing both charging and air pressure supply are the same as those in the first embodiment. Therefore, the operation mode of performing both discharging and air pressure supply will be described here.

[0097] When one of the pressure accumulators 13a-13c is at a high pressure near the storage pressure P3 and the pressures of the other pressure accumulators are reduced to a predetermined pressure of about P2, in this embodiment, as in the first embodiment, compressed air near the storage pressure P3 can be used to drive the expanders 14a, 14b, while compressed air at a predetermined pressure of about P2 can be supplied from the pressure accumulator 13 to the air compressor M1.

[0098] Furthermore, in this embodiment, as described above, by closing valve Ve and opening valve V35, compressed air from the same pressure accumulator can be supplied to the air compressor M1 via pipe 35, compressed air expanded and reduced in pressure in the first-stage expander 14a. In this case, if the pressure after the first-stage expansion, as detected by pressure sensor Se, has not dropped to the predetermined pressure P2, valve Ve can be opened by adjusting its opening rather than completely closing it. This allows the expander 14b to be driven, the generator 15b to generate electricity by adjusting its rotational speed, and simultaneously regulates the pressure of the compressed air used for the air supply.

[0099] (2-4) Adjustment of power supply and demand

[0100] The operation mode switching and power supply and demand adjustment of the CAES device 1 according to the present embodiment will be described.

[0101] (2-4a) When power generation exceeds power demand

[0102] When the power generation from the renewable energy power generation device connected to the power transmission and distribution system 5 exceeds the power consumption of the plant M, resulting in surplus power, the CAES system 1 operates in a charging mode. At this time, if the operating demand for the air compressor M1 is high and the air pressure usage is high, the CAES system 1 operates in a simultaneous charging and air pressure supply mode, supplying the air pressure used by the air compressor M1 from the pressure accumulator 13 without passing through the expander 14a.

[0103] (2-4b) When power generation is lower than power demand

[0104] If the power generated by the renewable energy generation equipment connected to the power transmission and distribution system 5 is less than the power consumption of the plant M, the CAES system 1 operates in a discharge mode, generating electricity from compressed air and supplying it to the power transmission and distribution system 5. At this time, if the operating demand for the air compressor M1 is high and the air pressure usage is high, the CAES system 1 operates in a simultaneous discharge and air pressure supply mode.

[0105] Here, in the case where there is a pressure accumulator container whose pressure is reduced to a predetermined pressure P2, in this embodiment, as in the first embodiment, compressed air is supplied to the air compressor M1 from the pressure accumulator container at the predetermined pressure P2 without passing through the expander 14a, and compressed air is supplied to the expanders 14a and 14b from other pressure accumulator containers at a pressure close to the storage pressure P3 to drive the generators 15a and 15b.

[0106] In this embodiment, when there is no pressure accumulator that has been depressurized to a predetermined pressure P2, compressed air at a high pressure close to the stored pressure P3 is supplied from one of the pressure accumulators 13a-13c to the expander 14a, driving the first-stage expander 14a to generate electricity. Simultaneously, compressed air, whose pressure has been depressurized by the expander 14a, is supplied to the air compressor M1 via piping 35. For example, when compressed air is supplied from the pressure accumulator 13a, the pressure of the pressure accumulator 13a is monitored by a pressure sensor S31. When the pressure of the pressure accumulator 13a drops to the predetermined pressure P2, valve VL1 is closed and valve V31 is opened, switching the mode to supply compressed air depressurized to the predetermined pressure P2 from the pressure accumulator 13a to the air compressor M1 via piping 31 without passing through the expander 14a. Simultaneously, compressed air is supplied from the other pressure accumulator 13b or 13c to the expanders 14a and 14b, driving the generators 15a and 15b.

[0107] (2-5) Effect

[0108] This embodiment achieves the same effects as the first embodiment. Furthermore, this embodiment enables an operating mode in which the expander 14a is driven to expand and generate electricity while simultaneously supplying compressed air via the pipe 35. While power generation is reduced in this operating mode, the energy of the stored compressed air can be recovered without loss by the expander 14a when the pressure is reduced from the high-pressure accumulator 13 to the operating pressure P1 of the air compressor M1. This minimizes energy loss associated with the compressed air supply, improving system efficiency (power recovery efficiency) compared to the first embodiment. When more power generation is required, the operating mode is switched to one in which the high-pressure accumulator drives the expanders 14a and 14b, while air is supplied from another accumulator, which has been depressurized to a predetermined pressure P2. In this case, switching the operating mode using operational control that incorporates information such as the required power generation, air pressure demand, and charging operation predictions (forecasts of power generation from renewable energy power generation devices) improves the system efficiency (air / power recovery efficiency) of the CAES system 1, including the air supply.

[0109] As described above, according to this embodiment, the compressed air stored in the pressure accumulator 13 can be used for either power generation or compressed air supply without being decompressed more than necessary, thereby providing a CAES device having high system efficiency including compressed air supply and capable of adjusting power supply and demand.

[0110] (Third embodiment)

[0111] Figure 3 It is a schematic diagram of a CAES device according to a third embodiment of the present invention. Figure 3 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0112] (3-1) CAES device

[0113] The CAES device 1 of this embodiment differs from the first embodiment in that the compressed air supply piping 30 is configured to include a piping 36 that connects the piping Lc1 connecting the low-pressure compressor 12a and the high-pressure compressor 12b to the air compressor M1. In this embodiment, the piping 36 connects the pipes Lc1 and 34. In addition, a valve V36 is provided in the piping 36, and a valve Vc is provided in the piping Lc1 (a portion located on the high-pressure compressor 12b side relative to the branch portion of the piping 36). Valves V36 and Vc are on-off valves similar to valve V31 and the like. The pressure sensor Sc is provided at a portion on the low-pressure compressor 12a side relative to the branch portion of the piping 36 in the piping Lc1. The hardware structure of the CAES device 1 of the third embodiment is otherwise the same as that of the first embodiment.

[0114] (3-2) Basic Actions

[0115] The operation of the CAES device 1 according to the third embodiment will be described. In this embodiment, the charging and discharging operations are the same as those in the first embodiment, so the air pressure supply operation will be described here.

[0116] In this embodiment, as in the first embodiment, compressed air can be supplied to the air compressor M1 sequentially starting from the pressure accumulator container whose pressure has been reduced to the prescribed pressure P2, and when there are multiple pressure accumulator containers with the prescribed pressure P2, compressed air can be supplied to the air compressor M1 preferentially from the pressure accumulator container with the lower pressure.

[0117] In addition, in this embodiment, by including a piping 36 in the air pressure supply piping 30, for example, closing the valve Vc and opening the valve V36, only the compressor 12a among the compressors 12a and 12b is operated, thereby allowing the compressed air compressed by the compressor 12a to flow through the piping 36 and to be supplied to the air compressor machine M1 while bypassing the pressure accumulation container 13.

[0118] (3-3) Operation Mode

[0119] The operating modes that can be executed in the first embodiment can also be executed in this embodiment in the same manner as in the first embodiment, with valve V36 closed and valve Vc open. In addition, this embodiment can also implement an operating mode in which only compressed air is supplied through pipe 36, an operating mode in which charging is performed while compressed air is supplied through pipe 36, and the like.

[0120] In the operating mode where only compressed air is supplied via piping 36, valve Vc is closed and valve V36 is opened as described above, driving only the first-stage compressor 12a of compressors 12a and 12b. This allows compressed air, compressed to a predetermined pressure P2 by compressor 12a, to be supplied to the air compressor M1 via piping 36 without being stored in the pressure accumulator 13, while the pressure is appropriately monitored by the pressure sensor Sc.

[0121] Furthermore, in an operating mode that simultaneously charges and supplies compressed air via pipe 36, valves Vc and V36 are both opened to drive compressors 12a and 12b. This allows a portion of the compressed air, compressed to a predetermined pressure P2 by compressor 12a, to flow through pipe 36 and be supplied to air compressor M1. Meanwhile, the remaining compressed air discharged from compressor 12a is further compressed by compressor 12b and stored in pressure accumulator 13.

[0122] (3-4) Adjustment of power supply and demand

[0123] The operation mode switching and power supply and demand adjustment of the CAES device 1 according to the present embodiment will be described.

[0124] (3-4a) When power generation exceeds power demand

[0125] When the power generation from the renewable energy generation devices connected to the power transmission and distribution system 5 exceeds the power consumption of the plant M, resulting in surplus power, the CAES system 1 operates in a charging mode. At this time, if the air compressor M1 experiences a high demand for operation and a high air pressure usage, the CAES system 1 operates in a simultaneous charging and air pressure supply mode. In this simultaneous charging and air pressure supply mode, if the amount of surplus power generated is high, compressors 12a and 12b need to be driven primarily for charging. Therefore, air pressure is supplied to the air compressor M1 from the pressure accumulator 13. If the amount of surplus power generated is low, driving both compressors 12a and 12b is unnecessary. Therefore, compressor 12b is stopped, and the air pressure supply from the pressure accumulator 13 to the air compressor M1 is stopped. Valve V36 is opened, and compressed air at a predetermined pressure P2, discharged from compressor 12a, is supplied to the air compressor M1.

[0126] (3-4b) When power generation is lower than power demand

[0127] If the power generated by the renewable energy generation equipment connected to the power transmission and distribution system 5 is less than the power consumption of the plant M, the CAES system 1 operates in a discharge mode, generating electricity from compressed air and supplying it to the power transmission and distribution system 5. At this time, if the operating demand for the air compressor M1 is high and the air pressure usage is high, the CAES system 1 operates in a simultaneous discharge and air pressure supply mode.

[0128] Here, in the case where there is a pressure accumulator container whose pressure is reduced to a predetermined pressure P2, in this embodiment, as in the first embodiment, air pressure is supplied to the air compressor M1 from the pressure accumulator container at the predetermined pressure P2 without passing through the expander 14a, and compressed air is supplied to the expanders 14a and 14b from other pressure accumulator containers at a pressure close to the storage pressure P3 to drive the generators 15a and 15b.

[0129] In this embodiment, if there is no pressure accumulator that has been depressurized to a predetermined pressure P2, compressed air at a high pressure close to the stored pressure P3 is supplied from one of the pressure accumulators 13a-13c (e.g., pressure accumulator 13a) to the expanders 14a and 14b, driving the generators 15a and 15b to generate electricity. Simultaneously, the compressor 12a is activated and valve V36 is opened, allowing the compressed air compressed by the compressor 12a to flow through the pipe 36 and be supplied to the air compressor M1. The pressure of the pressure accumulator 13a, which supplies compressed air to the expanders 14a and 14b, is monitored by a corresponding pressure sensor S31. When the pressure in the pressure accumulator 13a drops to the predetermined pressure P2, valve V31 is opened, switching the mode of operation to supply compressed air from the pressure accumulator 13a to the air compressor M1. Valve V36 in the pipe 36 is closed, and the compressor 12a is stopped.

[0130] (3-5) Effect

[0131] In this embodiment, the same effects as those of the first embodiment can be obtained. In addition, in this embodiment, an operation mode can be executed in which compressed air from the compressor 12a is supplied to the air compressor M1 from the piping 36. In the operation mode in which compressed air from the compressor 12a is supplied to the air compressor M1 from the piping 36, the charge amount is reduced, but since the compressor 12a only needs to compress the atmosphere to the prescribed pressure P2, the energy usage for air pressure supply can be suppressed, and high-efficiency operation can be achieved. Since the energy loss caused by air pressure supply can be suppressed, the system efficiency (power recovery efficiency) of the CAES device 1 is improved. When more charge amount is required, the mode is switched to supply air pressure from the pressure storage container. However, at this time, by switching the operation mode using operation control that introduces the necessary charge amount, air pressure demand, charging operation prediction, etc., the system efficiency (air pressure / power recovery efficiency) including air pressure supply can be improved.

[0132] (Fourth embodiment)

[0133] Figure 4 It is a schematic diagram of a CAES device according to a fourth embodiment of the present invention. Figure 4 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0134] (4-1) CAES device

[0135] The CAES device 1 of this embodiment differs from the first embodiment in that it has an air pressure supply unit 40 for supplying compressed air to the air compressor M1. In this embodiment, the air pressure supply unit 40 includes an air pressure supply compressor 41 dedicated to air pressure supply, which is different from the compressor 12, and pipes 42 and 43 connecting the air pressure supply compressor 41 to the air pressure supply piping 30. The piping 42 connects the air pressure supply compressor 41 to the air pressure container 44, and the piping 43 connects the air pressure container 44 to the piping 34 of the air pressure supply piping 30. A valve 45 is provided in the piping 43. The air pressure supply compressor 41 is driven by an electric motor (motor) 46 that is driven by grid power in the same way as the compressors 12a and 12b. In the air supply unit 40, an air supply compressor 41 draws in atmospheric air, compresses it to the operating pressure P1 of the air compressor M1 or to a predetermined pressure P2, and then delivers the compressed air to an air pressure container 44 via a pipe 42. The compressed air is then supplied to the air compressor M1 via a pipe 43 by opening and closing a valve 45. The hardware configuration of the CAES system 1 of the fourth embodiment is otherwise the same as that of the first embodiment.

[0136] (4-2) Basic Actions

[0137] The operation of the CAES device 1 according to the fourth embodiment will be described. In this embodiment, the charging and discharging operations are the same as those in the first embodiment, so the air pressure supply operation will be described here.

[0138] In this embodiment, as in the first embodiment, compressed air can be supplied to the air compressor M1 sequentially starting from the pressure accumulator container whose pressure has been reduced to the prescribed pressure P2, and when there are multiple pressure accumulator containers with the prescribed pressure P2, compressed air can be supplied to the air compressor M1 preferentially from the pressure accumulator container with the lower pressure.

[0139] In addition, in this embodiment, in addition to supplying compressed air from the pressure accumulator 13, compressed air can also be supplied from the air supply unit 40. When supplying compressed air from the air supply unit 40 to the air compressor M1, valves V31-V33 are closed to cut off the air supply from the pressure accumulator 13, and valve 45 of the air supply unit 40 is opened to operate the air supply compressor 41.

[0140] (4-3) Operation Mode

[0141] Regarding the operation modes that can be executed in the first embodiment, in this embodiment, they can also be executed in the same manner as in the first embodiment, with valve 45 closed and air supply compressor 41 stopped. In addition, in this embodiment, an operation mode in which air is supplied only by air supply compressor 41, an operation mode in which air is supplied while charging is performed, and the like can be executed.

[0142] First, in the operation mode where only the air supply compressor 41 is used for air supply, the compressors 12a, 12b and the expanders 14a, 14b are stopped and the valves V31-V33 are closed. Then, as described above, the valve 45 of the air supply unit 40 is opened and the air supply compressor 41 is operated.

[0143] Next, in the operating mode of performing charging action and simultaneously performing air pressure supply using the air pressure supply compressor 41, the compressors 12a, 12b and the air pressure supply compressor 41 are driven with the valves V31-V33 closed, thereby enabling the charging action of storing compressed air using the compressors 12a, 12b and the air pressure supply action of the air pressure supply unit 40 to be performed simultaneously.

[0144] (4-4) Adjustment of power supply and demand

[0145] The operation mode switching and power supply and demand adjustment of the CAES device 1 according to the present embodiment will be described.

[0146] (4-4a) When power generation exceeds power demand

[0147] When the power generation from the renewable energy generation devices connected to the power transmission and distribution system 5 exceeds the power consumption of the plant M, resulting in surplus power, the CAES system 1 operates in a charging mode. At this time, if the air compressor M1 experiences a high demand for operation and a high air pressure usage, the CAES system 1 operates in a simultaneous charging and air pressure supply mode. In this simultaneous charging and air pressure supply mode, when the amount of surplus power generated is high, compressors 12a and 12b need to be driven primarily for charging, so air pressure supply unit 40 is used to supply air pressure to the air compressor M1. When the amount of surplus power generated is low, driving both compressors 12a and 12b is unnecessary, so air pressure supply from air pressure supply unit 40 is stopped and air pressure supply from pressure accumulator 13 is switched. The method for supplying air pressure from pressure accumulator 13 has been described above. When air pressure supply from pressure accumulator 13 is sufficient, stopping air pressure supply unit 40 can reduce the power demand of air pressure supply unit 40.

[0148] (4-4b) When power generation is lower than power demand

[0149] If the power generated by the renewable energy generation equipment connected to the power transmission and distribution system 5 is less than the power consumption of the plant M, the CAES system 1 operates in a discharge mode, generating electricity from compressed air and supplying it to the power transmission and distribution system 5. At this time, if the operating demand for the air compressor M1 is high and the air pressure usage is high, the CAES system 1 operates in a simultaneous discharge and air pressure supply mode.

[0150] Here, in the case where there is a pressure storage container whose pressure is reduced to a specified level P2, in this embodiment, as in the first embodiment, compressed air is supplied to the air compressor M1 from the pressure storage container at the specified level P2 without passing through the expander 14a, and compressed air is supplied to the expanders 14a and 14b from other pressure storage containers close to the storage pressure P3 to drive the generators 15a and 15b.

[0151] In this embodiment, if there is no pressure accumulator vessel capable of reducing the pressure to a predetermined pressure P2, compressed air at a high pressure close to the stored pressure P3 is supplied from one of the pressure accumulator vessels 13a-13c (e.g., pressure accumulator vessel 13a) to the expanders 14a and 14b, driving the generators 15a and 15b to generate electricity. Simultaneously, the air supply unit 40 activates the air supply compressor 41 and opens valve 45, allowing compressed air compressed by the air supply compressor 41 to flow through pipe 43 and be supplied to the air compressor M1. The pressure of the pressure accumulator vessel 13a, which supplies compressed air to the expanders 14a and 14b, is monitored by a corresponding pressure sensor S31. When the pressure in the pressure accumulator vessel 13a is reduced to the predetermined pressure P2, valve V31 is opened, switching the mode of operation to supply compressed air from the pressure accumulator vessel 13a to the air compressor M1, and stopping the air supply unit 40.

[0152] (4-5) Effect

[0153] This embodiment also achieves the same effects as the first embodiment. Furthermore, this embodiment enables an operating mode in which air pressure is supplied by the air pressure supply unit 40. While this operating mode increases the power demand of CAES1, since the air pressure supply unit 40 is dedicated to supplying air pressure to the air compressor M1, the air pressure supply design can be optimized, minimizing any reduction in system efficiency (power recovery efficiency).

[0154] (Fifth embodiment)

[0155] Figure 5 It is a schematic diagram of a CAES device according to a fifth embodiment of the present invention. Figure 5 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0156] The CAES device 1 of this embodiment is different from the first embodiment in that it includes a water supply pump 50 connected to the pressure storage container 13 to increase the tank pressure of the pressure storage container 13 . Figure 5While the example illustrates a configuration in which water is supplied to the pressure accumulator 13c using the water supply pump 50, a configuration in which water is supplied to at least one of the pressure accumulators 13a-31c using the water supply pump 50 can also be employed. In this embodiment, for example, if the pressure of the pressure accumulator 13 to be used for air pressure supply falls below the specified pressure P2 or the air pressure specification pressure P1, and air pressure cannot be supplied to the air compressor M1, the water supply pump 50 can be used to increase the internal pressure of the pressure accumulator 13 by supplying water to the pressure accumulator 13. This allows the compressed air, which falls below the specified pressure P2, to be supplied to the air compressor M1. Alternatively, for example, a configuration can be employed in which the pressure sensors S31-S33 monitor the pressure of the pressure accumulator 13, which decreases as air pressure is supplied. Once the pressure of the pressure accumulator 13 drops to the specified pressure P2 or the air pressure specification pressure P1 (or a value set with a margin relative to these values), the water supply pump 50 is driven to maintain the pressure of the pressure accumulator 13 at a pressure sufficient for air pressure supply, thereby continuing air pressure supply. In this case, a configuration can be adopted in which the driving and stopping of the water supply pump 50 are feedback-controlled using the predetermined pressure P2 or the air pressure specification pressure P1 (or a set value set with a margin for these values) as a threshold value.

[0157] This type of air pressure supply from the pressure accumulator 13 using the water supply pump 50 can also be performed simultaneously with charging or discharging operations. For example, if the pressure accumulators 13a and 13b have a high pressure storage pressure of approximately P3, but the pressure accumulator 13c is below the predetermined pressure P2, the pressure accumulator 13a can be used for discharge while simultaneously supplying air pressure from the pressure accumulator 13c by increasing the pressure using the water supply pump 50. Alternatively, if both pressure accumulators 13b and 13c are below the predetermined pressure P2, compressed air can be stored in the pressure accumulator 13b while simultaneously supplying air pressure from the pressure accumulator 13c by increasing the pressure using the water supply pump 50.

[0158] Furthermore, when the pressure of the pressure storage container 13 is lower than the pressure that can be used for the discharge operation, the water supply pump 50 can be used to increase the pressure of the pressure storage container 13 to the pressure that can be used for the discharge operation.

[0159] The water injected from the water supply pump 50 into the pressure accumulator 13 is appropriately drained from a drain pipe (not shown) when the compressed air is stored in the pressure accumulator 13 .

[0160] The hardware configuration of the CAES device 1 of the fifth embodiment is otherwise the same as that of the first embodiment. In addition to the aforementioned air pressure supply and discharge operations using the water supply pump 50 and the corresponding operating modes, this embodiment also implements the basic operations and operating modes, as well as power supply and demand adjustments, that were implemented in the first embodiment.

[0161] This embodiment also achieves the same effects as the first embodiment. Furthermore, in this embodiment, even if the pressure in the pressure accumulator 13 is insufficient to supply air pressure, the water supply pump 50 can be used to increase the pressure in the pressure accumulator 13 and provide air pressure. While the operation mode in which the water supply pump 50 is driven increases the power demand of the CAES 1, because the water supply pump 50 is dedicated to supplying air pressure to the air compressor M1, the air pressure supply design can be optimized, minimizing the reduction in system efficiency (power recovery efficiency).

[0162] (Sixth embodiment)

[0163] Figure 6 It is a schematic diagram of a CAES device according to a sixth embodiment of the present invention. Figure 6 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0164] This embodiment is an example of a combination of the second embodiment and the third embodiment. The actions and operating modes that can be implemented in the second or third embodiment can also be implemented in this embodiment. Switching between the various operating modes can be performed using an operating control that incorporates the required charge amount, required power generation amount, air pressure demand, and charge / discharge operation predictions. By switching the operating mode, the system efficiency (air pressure / power recovery efficiency) including the air pressure can be improved.

[0165] As shown in this example, any two or more of the first to fifth embodiments described above can be combined.

[0166] (Seventh embodiment)

[0167] Figure 7 It is a schematic diagram of a CAES device according to a seventh embodiment of the present invention. Figure 7 Elements identical or corresponding to those in the already described embodiments are denoted by the same reference numerals as in the existing drawings, and description thereof is omitted as appropriate.

[0168] This embodiment shows an example of a specific hardware configuration for implementing control such as switching of valves mentioned in each embodiment. Figure 7 In the CAES system 1, a control device 70 is provided, which has functions such as controlling valves V31-V33 and VL1-VL5 based on the pressure of the air supply pipe 30 detected by pressure sensors S31-S34. While this embodiment describes an example in which the control device 70 is added to the first embodiment, the control device 70 can also be added to the second through sixth embodiments in a similar manner to implement control such as valve switching.

[0169] The control device 70 is connected to the pressure sensors S31-S34, Sc, and Se, the power conditioner 4, and the power meter 71 of the factory M (which may also be a computer in the management office of the factory M, etc.), and receives input data such as the pressure detected by the pressure sensors S31-S34, Sc, and Se, the power generated by the renewable energy power generation device, and the power demand of the factory M (the power demand of the entire factory M and the power demand of the air compressor system). The control device 70 is a computer that executes the control program of the CAES system 1. In this embodiment, the valves V31-V33 and VL1-VL5 are electromagnetically driven. Although not shown, the control device 70 is electrically connected to the valves V31-V33, VL1-VL5, the motors 11a and 11b, the generators 15a and 15b, and the pumps 28 and 29, and outputs operation commands to these electric machines. For example, the control device 70 can output opening and closing commands to valves V31-V33 and VL1-VL5, start commands / stop commands / rotation speed commands to the motors 11a, 11b and pumps 28, 29, and rotation speed commands to the generators 15a, 15b.

[0170] The control device 70 receives the power generated by the renewable energy power generation device from the power conditioner 4, the power consumption of the plant M from the power meter 71, and the pressure of the air supply pipe 30 detected by the pressure sensors S31-S34. For example, if the power generated by the renewable energy power generation device is less than the power consumption of the plant M and the pressure of the air supply pipe 30 is above the air pressure operating pressure P1 and below the predetermined pressure P2, the control device 70 appropriately opens valves V31-V33 to supply compressed air from the air supply pipe 30 to the air compressor M1. For example, if only the pressure storage tank 13c (pipe 33) of the pressure storage tanks 13a-13c (pipes 31-33) is within the aforementioned pressure range, the control device 70 opens valve V33 to supply compressed air using the pressure storage tank 13c.

[0171] To automatically control the electric machine including valves V31-V33 and VL1-VL5, the control device 70 must determine the operating mode to be selected. To determine the operating mode, the relationship between the power generation of the renewable energy power generation device and the power consumption of the plant M must first be determined, as described in the "Power Supply and Demand Adjustment" section of the first embodiment. This determination can be made by the control device 70 based on the power generation of the renewable energy power generation device input from the power conditioner 4 and the power consumption of the plant M input from the power meter 71. Consequently, the control device 70 selects a charging operating mode when power generation exceeds power consumption, a discharging operating mode when power generation falls short, and an air pressure supply-only operating mode when power generation and power consumption are balanced, controlling the electric machine accordingly. In this case, when either the charging or discharging operating mode is selected, the control device 70 determines whether to simultaneously perform the air pressure supply operation based on, for example, whether the operating demand for air compressor M1 in the plant M exceeds a predetermined threshold. The operating requirement of the air compressor M1 can be estimated based on, for example, the power consumption of the air compressor system (or the piping pressure of the air compressor system, etc.).

[0172] As shown in this embodiment, by automatically operating the CAES device 1 , the CAES device 1 can be operated in an appropriate operation mode at an appropriate time, and energy efficiency can be further improved.

[0173] (Variation)

[0174] In the above embodiments, renewable energy power generation devices can encompass any device that utilizes energy that is steadily (or repeatedly) replenished and erratically fluctuates through natural forces, such as wind, sunlight, solar heat, wave or tidal forces, flowing water or tides, and geothermal energy. Furthermore, the CAES device 1 of each embodiment can be applied even when the power demand of the factory M fluctuates significantly depending on the operating conditions of high-power-consuming equipment within the factory M. Furthermore, the power transmission and distribution system 5 is not limited to the general power transmission and distribution system of a power company; it may also be a microgrid system within a region or the factory M.

[0175] In addition, as the compressors 12a, 12b and expanders 14a, 14b of each embodiment, for example, screw-type ones can be used, but the form of these rotary machines is not limited. As the compressors 12a, 12b and expanders 14a, 14b, for example, scroll-type ones, turbine-type ones, or reciprocating-type ones may also be used.

[0176] In addition, in each embodiment, the compressor 12 and the expander 14 are configured as two-stage compression / two-stage expansion types, with compressors 12a and 12b and expanders 14a and 14b, respectively. However, the compressor 12 and the expander 14 may also be single-stage compression / single-stage expansion types, or three or more stages of compression / expansion types, and the number of compression and expansion stages may also be different. Furthermore, although each figure shows one compressor 12 and one expander 14, the number is not particularly limited, and the CAES device 1 may include multiple compressors 12 and expanders 14. In addition, there are also cases where the number of motors and compressors is different (for example, when one motor drives multiple compressors), or the number of generators and expanders is different (for example, when multiple expanders drive one generator).

[0177] In addition, for example Figure 2 In the example, a structure is shown in which compressed air is extracted from the pipe Le2 connecting the high-pressure expander 14a and the low-pressure expander 14b of the multi-stage expansion type expander 14, but a structure in which compressed air is extracted from the middle of a single-stage expander can also be adopted. Figure 3 The same is true for the example of , and a structure can be adopted in which compressed air is extracted from the middle of a single-stage compressor.

[0178] Explanation of symbols

[0179] 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), 11...motor, 12...compressor, 12a...compressor (low-pressure compressor), 12b...compressor (high-pressure compressor), 13...pressure accumulator, 14...expander, 14a...expander (high-pressure expander), 14b...expander (low-pressure expander), 15...generator, 30...air supply piping, 31-36...piping, 41...air supply compressor, 42, 43...piping, 50...water supply pump, 70...control device, Lc1, Le2...piping, M...factory (facility using air compressor), M1...air compressor, P1...air operating pressure, P2...specified pressure, S33-S34...pressure sensor, V31-V33...valves (on / off valves).

Claims

1. A compressed air energy storage device comprising: a compressor, which is driven by an electric motor; a pressure accumulator container for storing compressed air compressed by the compressor; an expander driven by the compressed air stored in the pressure accumulator; a generator driven by the expander; and Air pressure supply piping, which supplies the compressed air to the air compressor equipment driven by air pressure, The air is compressed by the compressor to a pressure exceeding a predetermined pressure set higher than the air pressure used to drive the air compressor. The expander is supplied with compressed air exceeding the predetermined pressure to generate electricity. Compressed air having a pressure not greater than the predetermined pressure is supplied to the air compressor through the air supply pipe.

2. The compressed air energy storage device according to claim 1, wherein: have: a pressure sensor for detecting the pressure of the air pressure supply pipe; an on-off valve provided in the air pressure supply pipe; and a control device for controlling the on-off valve based on the pressure of the air pressure supply pipe detected by the pressure sensor, The electric motor is driven by electricity from a power transmission and distribution system connected to a renewable energy power generation device. For the control device, When the power generation of the renewable energy power generation device, the power consumption of the facility using the air compressor, and the pressure of the air supply pipe detected by the pressure sensor are input, When the power generation amount is less than the power consumption and the pressure of the air supply pipe is greater than or equal to the air operating pressure and less than or equal to the predetermined pressure, the on-off valve is opened to supply the compressed air from the air supply pipe to the air compressor.

3. The compressed air energy storage device according to claim 1, wherein: The air pressure supply piping is configured to include piping connecting the pressure accumulator container and the air compressor equipment.

4. The compressed air energy storage device according to claim 1, wherein: The expansion mechanism includes a high-pressure expander driven by compressed air from the pressure accumulator and a low-pressure expander driven by compressed air discharged from the high-pressure expander. The compressed air supply piping is configured to include piping connecting the piping connecting the high-pressure expander and the low-pressure expander to the air compressor.

5. The compressed air energy storage device according to claim 1, wherein: The compression mechanism includes a low-pressure compressor and a high-pressure compressor for compressing the compressed air compressed by the low-pressure compressor. The compressed air supply pipe is configured to include a pipe connecting a pipe connecting the low-pressure compressor and the high-pressure compressor to the air compressor.

6. The compressed air energy storage device according to claim 1, comprising: an air supply compressor at a pressure different from that of the compressor; and A pipe connecting the air pressure supply compressor and the air pressure supply pipe.

7. The compressed air energy storage device according to claim 1, wherein: A water supply pump is provided which is connected to the pressure accumulating container and increases the container pressure of the pressure accumulating container.

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