Power control device, power control method, and power control program

Abstract

A power control device according to one aspect disclosed herein controls SOEC power supply using power based on renewable energy. This power control device comprises: a power separation unit that separates power based on renewable energy into a first power component and a second power component; a heat generation device that generates thermal energy using the first power component; a heat storage device that stores the thermal energy and outputs steam; and a cell stack that generates hydrogen using the second power component and the steam. The first power component includes a fluctuation component of the power based on renewable energy.

Description

Power control device, power control method, and power control program

[0001] The present disclosure relates to a power control device, a power control method, and a power control program.

[0002] A hydrogen production device using a solid oxide electrolyzer cell (hereinafter referred to as "SOEC") is known. The SOEC generates steam from water using an electric heater and heats and electrolyzes the steam.

[0003] In the SOEC, the flow rate of steam is proportional to the power used for electrolysis. When power fluctuations occur in the SOEC, the ratio of the steam flow rate to the power changes. As a result, the operation of the SOEC becomes unstable. Therefore, conventional SOECs are operated independently using a stable power source. Examples of technologies that consider power fluctuations include the technologies described in Patent Documents 1 to 3.

[0004] Patent Document 1 discloses a technology for ensuring the balance between power demand and supply. The technology described in Patent Document 1 divides the error between the target value and the actual value of the integrated amount of grid power into a low-frequency component that fluctuates over a long period and a high-frequency component that fluctuates over a short period. The technology described in Patent Document 1 allocates the low-frequency component to the power consumption device and the high-frequency component to the energy storage device.

[0005] Patent Document 2 discloses a technology for managing the power supply of renewable energy in a water electrolysis system. The technology described in Patent Document 2 calculates an electrolysis power command value using an estimated value of surplus power and an allowable ramp rate of the electrolyzer.

[0006] Patent Document 3 discloses a technology for managing the power supply of renewable energy in a hydrogen production system that combines a water electrolysis cell and an SOEC. The technology described in Patent Document 3 separates surplus power into stable power and unstable power, supplies stable power to the SOEC, and supplies unstable power to the water electrolysis cell.

[0007] International Publication No. 2022 / 054441 Japanese Patent Application Laid-Open No. 2023-172003 Japanese Patent Application Laid-Open No. 2019-173082

[0008] Within SOEC, there is a need for technologies that can track fluctuations in electricity output based on renewable energy.

[0009] This disclosure describes a technology capable of tracking fluctuations in the output of electricity based on renewable energy.

[0010] A power control device relating to one aspect of this disclosure controls the power supply of an SOEC using electricity based on renewable energy. The power control device includes a power separation unit that separates electricity based on renewable energy into a first power component and a second power component, a heat generation device that generates thermal energy using the first power component, a heat storage device that stores thermal energy and outputs steam, and a cell stack that generates hydrogen using the second power component and steam. The first power component includes a fluctuating component of electricity based on renewable energy.

[0011] This disclosure provides a technology that can track fluctuations in the output of electricity based on renewable energy.

[0012] Figure 1 is a diagram showing an example of the configuration of a power control device according to an embodiment. Figure 2 is a flowchart showing an example of the operation of the power control device. Figure 3 is a diagram showing an example of the hardware configuration related to the power control device.

[0013] A power control device relating to one aspect of this disclosure controls the power supply of an SOEC using electricity based on renewable energy. The power control device includes a power separation unit that separates electricity based on renewable energy into a first power component and a second power component, a heat generation device that generates thermal energy using the first power component, a heat storage device that stores thermal energy and outputs steam, and a cell stack that generates hydrogen using the second power component and steam. The first power component includes a fluctuating component of electricity based on renewable energy.

[0014] A power control method relating to one aspect of this disclosure is performed by a power control device that controls the power supply of an SOEC using renewable energy-based electricity. The power control method comprises the steps of: separating renewable energy-based electricity into a first power component and a second power component; generating thermal energy using the first power component; storing the thermal energy and outputting steam; and generating hydrogen using the second power component and steam. The first power component includes a fluctuating component of renewable energy-based electricity.

[0015] A power control program relating to one aspect of this disclosure controls the power supply of SOEC using renewable energy-based electricity. The power control program causes a computer to perform the following steps: separate renewable energy-based electricity into a first power component and a second power component; generate thermal energy using the first power component; store the thermal energy and output steam; and generate hydrogen using the second power component and steam. The first power component includes a fluctuating component of renewable energy-based electricity.

[0016] According to a power control device, power control method, and power control program relating to one aspect of this disclosure, electricity based on renewable energy is separated into a first power component and a second power component. The first power component, including a fluctuating component, is supplied to a heat generator, and the second power component is supplied to a cell stack. Before steam is supplied to the cell stack, the thermal energy generated using the first power component is stored in a heat storage device. The heat storage device functions as a buffer, which can mitigate fluctuations in the output of electricity based on renewable energy. As a result, SOEC can follow fluctuations in the output of electricity based on renewable energy.

[0017] The first power component may include the first fluctuating component of renewable energy-based power. The second power component may include the second fluctuating component of renewable energy-based power. The frequency of the first fluctuating component may be higher than the frequency of the second fluctuating component. In this case, the second fluctuating component represents the long-term trend of fluctuations in renewable energy-based power. The first fluctuating component represents the short-term trend of fluctuations in renewable energy-based power. The short-term fluctuating component is consumed by the heat generator, while the long-term fluctuating component is consumed by the cell stack. This enables stable operation of the SOEC in line with the time-dependent fluctuations of renewable energy-based power.

[0018] The second power component does not necessarily have to include the fluctuating component of electricity based on renewable energy. In this case, the second power component supplied to the cell stack becomes stable, thus stabilizing the operation of the cell stack.

[0019] The heat generator may produce steam as thermal energy. The power output sensitivity is low with respect to the amount of steam produced. That is, even if the first power component for steam production fluctuates greatly, the amount of steam produced does not fluctuate greatly. Therefore, the heat generator can efficiently mitigate fluctuations in power output based on renewable energy. Furthermore, even in SOECs with a low load change rate (Ramp Rate) for steam production, it can cope with fluctuations in power based on renewable energy.

[0020] The power separation unit may determine whether the second power component meets the criteria for operating the cell stack, and if it does not, it may control the supply of both the first and second power components to the heat generator. In this case, instability in the operation of the cell stack can be avoided. In addition, thermal energy can be stored in the heat storage device in advance. As a result, the operation of the SOEC becomes more stable.

[0021] Embodiments of this disclosure will be described below with reference to the drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted.

[0022] Figure 1 is a schematic diagram showing an example of the configuration of a power control device 1 (power control system) according to an embodiment. The power control device 1 is a device that controls the power supply of SOEC using electricity based on renewable energy. "Electricity based on renewable energy" refers to electricity generated using renewable energy. Examples of renewable energy include, but are not limited to, solar, wind, hydro, or geothermal energy. Hereinafter, electricity based on renewable energy will be referred to as "renewable energy electricity". The power control device 1 comprises a hydrogen production device 2 and a power separation unit 5.

[0023] The hydrogen production apparatus 2 is a SOEC (Steam-Oxidized Electrical Condensation) apparatus that produces hydrogen by electrolysis of heated steam. The hydrogen production apparatus 2 is connected to the power source 3 via connection point 4. The hydrogen production apparatus 2 is also connected to the power isolation unit 5 in a communication manner.

[0024] Power source 3 supplies renewable energy to connection point 4. The configuration of power source 3 is not limited. For example, power source 3 may be a solar power generation facility that generates electricity using sunlight. Power source 3 may also be a combination of multiple power generation facilities.

[0025] Connection point 4 supplies renewable energy electricity from power source 3 to hydrogen production device 2. Connection point 4 functions as a Point of Interconnection (PoI), which is a physical contact point for electricity. The renewable energy electricity supplied from connection point 4 to hydrogen production device 2 is alternating current electricity. Connection point 4 measures the power [kW] of the renewable energy electricity and transmits the measured value to power separation unit 5. Connection point 4 may also transmit the energy amount [kWh] to power separation unit 5.

[0026] The power isolation unit 5 is, for example, an EMS (Energy Management System). The power isolation unit 5 may be located outside the hydrogen production apparatus 2 or may be incorporated into the hydrogen production apparatus 2. The power isolation unit 5 controls the power supply to the hydrogen production apparatus 2, as described later. The power isolation unit 5 may generate control commands for the equipment inside the hydrogen production apparatus 2. The power isolation unit 5 may acquire the power consumption or energy consumption of the equipment inside the hydrogen production apparatus 2.

[0027] The hydrogen production apparatus 2 comprises a pure water production apparatus 6, a pure water tank 7, a pump 8, a heat generator 9, a heat storage apparatus 10, a first heat exchanger 11, a first preheater 12, a blower 13, a second heat exchanger 14, a second preheater 15, a rectifier 16, a cell stack 17, a cooler 18, a gas-liquid separator 19, and a compressor 20.

[0028] The pure water production apparatus 6 is a device that produces pure water, for example, by removing impurities from tap water. The pure water tank 7 is a tank that stores the pure water produced by the pure water production apparatus 6. The pure water tank 7 may also store pure water separated by the gas-liquid separator 19, which will be described later. The pump 8 supplies the pure water stored in the pure water tank 7 to the heat generator 9. If the flow rate of pure water is excessive for the heat generator 9, the pump 8 returns the pure water to the pure water tank 7.

[0029] The heat generator 9 generates thermal energy and supplies the generated thermal energy to the heat storage device 10. For example, the heat generator 9 is a vaporizer that generates steam as thermal energy. The heat generator 9 heats pure water supplied from the pump 8 to generate steam. The heat generator 9 supplies the generated steam to the heat storage device 10.

[0030] The heat storage device 10 stores the thermal energy generated by the heat generation device 9. The heat storage device 10 may be, for example, a steam accumulator that stores steam itself. The heat storage device 10 outputs steam based on the thermal energy. The heat storage device 10 adjusts the amount of steam supplied to the first heat exchanger 11 according to the amount of steam used by the cell stack 17, which will be described later. For example, the heat storage device 10 increases or decreases the amount of steam supplied in response to an increase or decrease in the amount of steam used.

[0031] The first heat exchanger 11 heats the steam supplied from the heat storage device 10. The first heat exchanger 11 supplies the heated steam to the first preheater 12. For example, the first heat exchanger 11 heats the steam using high-temperature hydrogen generated by the cell stack 17, which will be described later. The first heat exchanger 11 supplies the hydrogen used to heat the steam to the cooler 18.

[0032] The first preheater 12 reheats the steam supplied from the first heat exchanger 11. The first preheater 12 further increases the temperature of the steam through reheating. The first preheater 12 supplies the reheated steam to the cell stack 17.

[0033] Blower 13 takes in ambient air. Blower 13 supplies the taken-in air to the second heat exchanger 14.

[0034] The second heat exchanger 14 heats the air supplied from the blower 13 and supplies the air to the second preheater 15. For example, the second heat exchanger 14 heats the air using high-temperature oxygen generated by the cell stack 17, which will be described later. The second heat exchanger 14 then discharges the oxygen used to heat the air back into the air.

[0035] The second preheater 15 reheats the air supplied from the second heat exchanger 14. The second preheater 15 further increases the temperature of the air through reheating. The second preheater 15 supplies the reheated air to the cell stack 17. The air is used for cooling the cell stack 17, etc. The air is heated to suppress rapid temperature changes in the cell stack 17.

[0036] The rectifier 16 converts AC power to DC power. The rectifier 16 supplies the DC power to the cell stack 17.

[0037] The cell stack 17 generates hydrogen and oxygen by electrolyzing the steam supplied from the first preheater 12. The hydrogen and oxygen are at high temperatures. The cell stack 17 supplies hydrogen to the first heat exchanger 11 and oxygen to the second heat exchanger 14.

[0038] The cooler 18 cools the hydrogen supplied from the first heat exchanger 11. The cooler 18 supplies the cooled hydrogen to the gas-liquid separator 19.

[0039] The gas-liquid separator 19 removes water from the hydrogen. The gas-liquid separator 19 supplies the hydrogen from which the water has been removed to a designated hydrogen tank, etc., and also supplies a portion of the hydrogen to the compressor 20. The gas-liquid separator 19 supplies the removed water to the pure water tank 7.

[0040] The compressor 20 supplies hydrogen supplied from the gas-liquid separator 19 to the first heat exchanger 11. The steam supplied to the cell stack 17 needs to have a predetermined amount of hydrogen mixed in. Therefore, the hydrogen supplied from the compressor 20 is supplied to the first heat exchanger 11 together with the steam supplied from the heat storage device 10.

[0041] In the power control device 1, the power separation unit 5 controls the supply of power to the hydrogen production device 2. For example, the power separation unit 5 acquires the renewable energy power measured at the connection point 4. The power separation unit 5 records the acquired power in chronological order. The power separation unit 5 may also record predicted future power. The power separation unit 5 may process either power [kW] or energy [kWh].

[0042] The power separation unit 5 separates renewable energy power into a first power component P1 and a second power component P2 using time-series power data. The time-series power data may be at least one of the power obtained from the connection point 4 (current power), past power, and future power. The first power component P1 includes the fluctuating component of renewable energy power. For example, the first power component P1 may include some or all of the fluctuating component. The second power component P2 may or may not include the fluctuating component.

[0043] The method for separating renewable energy power is not limited. The first power component P1 may be the difference with respect to the second power component P2. For example, the power separation unit 5 may apply a moving average filter to the renewable energy power as the input signal. The power separation unit 5 may use the input signal smoothed using the moving average filter as the second power component P2, and the signal obtained by subtracting the second power component P2 from the original input signal as the first power component P1. The power separation unit 5 may also use a first-order lag filter with a gain of 1 to smooth the input signal.

[0044] The second power component P2 may include a fluctuating component. For example, the first power component P1 may include a first fluctuating component of renewable energy power. The second power component P2 may include a second fluctuating component of renewable energy power. The frequency of the first fluctuating component is higher than the frequency of the second fluctuating component. The first fluctuating component indicates a tendency of short-term fluctuations in renewable energy power. The second fluctuating component indicates a tendency of long-term fluctuations in renewable energy power.

[0045] The second power component P2 may not include a fluctuating component. That is, the power separation unit 5 may apply a fluctuating component only to the first power component P1.

[0046] In addition to a constant power for operating the heat generation device 9, the first power component P1 may include a fluctuating component. The second power component P2 includes a constant power for operating the cell stack 17 and may not include a fluctuating component.

[0047] The power separation unit 5 controls to supply the first power component P1 to the heat generation device 9. The heat generation device 9 operates using the first power component P1. The power separation unit 5 controls to supply the second power component P2 to the rectifier 16. The rectifier 16 supplies the second power component P2 converted into DC power to the cell stack 17. The cell stack 17 operates using the second power component P2 supplied via the rectifier 16.

[0048] In the power control device 1, the pure water production device 6, the pure water tank 7, and the pump 8 may be configured as a water supply device. The heat storage device 10 and the heat generation device 9 may be configured as a steam supply device. The cooler 18, the gas-liquid separator 19, and the compressor 20 may be configured as a hydrogen extraction device.

[0049] An example of a power control method executed by the power control device 1 will be described while referring to FIG. 2. FIG. 2 is a flowchart showing an example of the operation of the power control device 1 as a processing flow M. In FIG. 2, the pure water tank 7 is described as storing pure water produced by the pure water production device 6.

[0050] In step S1, the power separation unit 5 acquires the renewable energy power measured at the connection point 4. The power separation unit 5 records the acquired power in chronological order. The power separation unit 5 may also record predicted future power. The power separation unit 5 may process either power [kW] or energy [kWh].

[0051] In step S2, the power separation unit 5 separates the renewable energy power into a first power component P1 and a second power component P2 using time-series power data. The time-series power data may be at least one of the power obtained from the connection point 4 (current power), past power, and future power. The first power component P1 includes the fluctuating component of the renewable energy power. For example, the first power component P1 may include some or all of the fluctuating component. The second power component P2 may or may not include the fluctuating component.

[0052] In step S3, the power separation unit 5 controls the supply of the first power component P1 to the heat generator 9. The power separation unit 5 also controls the supply of the second power component P2 to the rectifier 16. The rectifier 16 supplies the second power component P2, which has been converted to DC power, to the cell stack 17.

[0053] In step S4, the heat generator 9 generates thermal energy using the first power component P1. The heat generator 9 supplies the generated thermal energy to the heat storage device 10. For example, the heat generator 9 heats the pure water supplied from the pump 8 to generate steam. The heat generator 9 supplies the generated steam to the heat storage device 10.

[0054] In step S5, the heat storage device 10 stores the thermal energy generated by the heat generator 9. The heat storage device 10 outputs steam based on the thermal energy. The heat storage device 10 adjusts the amount of steam supplied to the first heat exchanger 11 according to the amount of steam used by the cell stack 17. For example, the heat storage device 10 increases or decreases the amount of steam supplied in response to an increase or decrease in the amount of steam used.

[0055] Steam is supplied to the cell stack 17 via the first heat exchanger 11 and the first preheater 12. Air is also supplied to the cell stack 17 via the blower 13, the second heat exchanger 14, and the second preheater 15.

[0056] In step S6, the cell stack 17 generates hydrogen using the second power component P2 and steam. The cell stack 17 generates hydrogen and oxygen by electrolyzing the steam supplied from the first preheater 12. The cell stack 17 supplies hydrogen to the first heat exchanger 11 and oxygen to the second heat exchanger 14.

[0057] Hydrogen is extracted via the first heat exchanger 11, the cooler 18, and the gas-liquid separator 19. A portion of the hydrogen is supplied to the first heat exchanger 11 via the compressor 20. Oxygen is discharged via the second heat exchanger 14.

[0058] [Hardware Configuration] Figure 3 shows an example of the hardware configuration related to the power control device 1. Figure 3 shows a computer 100 that functions as a control device or power isolation unit 5 of the hydrogen production apparatus 2. The computer 100 has a CPU (Central Processing Unit) 101, a main memory unit 102, an auxiliary memory unit 103, a communication control unit 104, an input device 105, and an output device 106. The control device or power isolation unit 5 of the hydrogen production apparatus 2 is composed of one or more computers 100 which consist of this hardware and software such as programs.

[0059] If the control device or power isolation unit 5 of the hydrogen production apparatus 2 is composed of multiple computers 100, these computers 100 may be connected locally or via a communication network such as the Internet or an intranet. This connection logically constructs a single control device or power isolation unit 5 of the hydrogen production apparatus 2.

[0060] The CPU 101 executes the operating system and application programs. The main memory 102 consists of ROM (Read Only Memory) and RAM (Random Access Memory). The auxiliary memory 103 is a storage medium consisting of a hard disk and flash memory. The auxiliary memory 103 generally stores a larger amount of data than the main memory 102. The communication control unit 104 consists of a network card or a wireless communication module. At least part of the communication function between the control unit of the hydrogen production apparatus 2 or the power separation unit 5 and other devices may be implemented by the communication control unit 104. The input device 105 consists of a keyboard, mouse, touch panel, and microphone for voice input. The output device 106 consists of a display and printer.

[0061] The auxiliary storage unit 103 stores the program 110 and the data necessary for processing in advance. The program 110 causes the computer 100 to execute each functional element of the control device or power separation unit 5 of the hydrogen production apparatus 2. The program 110 allows the computer 100 to execute, for example, the processing related to the control method described above. For example, the program 110 is read by the CPU 101 or the main memory unit 102 and operates at least one of the CPU 101, the main memory unit 102, the auxiliary storage unit 103, the communication control unit 104, the input device 105, and the output device 106. For example, the program 110 reads and writes data to the main memory unit 102 and the auxiliary storage unit 103.

[0062] The program 110 may be provided on a tangible storage medium such as a CD-ROM, DVD-ROM, or semiconductor memory. The program 110 may also be provided as a data signal via a communication network.

[0063] As described above, the power control device 1 according to one aspect of this disclosure controls the power supply of SOEC using electricity based on renewable energy. The power control device 1 includes a power separation unit 5 that separates electricity based on renewable energy into a first power component P1 and a second power component P2, a heat generation device 9 that generates thermal energy using the first power component P1, a heat storage device 10 that stores thermal energy and outputs steam, and a cell stack 17 that generates hydrogen using the second power component P2 and steam. The first power component P1 includes a fluctuating component of electricity based on renewable energy.

[0064] A power control method relating to one aspect of this disclosure is performed by a power control device 1 that controls the power supply of an SOEC using renewable energy-based electricity. The power control method includes the steps of: separating renewable energy-based electricity into a first power component P1 and a second power component P2; generating thermal energy using the first power component P1; storing the thermal energy and outputting steam; and generating hydrogen using the second power component P2 and steam. The first power component P1 includes a fluctuating component of renewable energy-based electricity.

[0065] A power control program (program 110) relating to one aspect of this disclosure controls the power supply of SOEC using renewable energy-based electricity. The power control program causes the computer 100 to perform the following steps: separate the renewable energy-based electricity into a first power component P1 and a second power component P2; generate thermal energy using the first power component P1; store the thermal energy and output steam; and generate hydrogen using the second power component P2 and steam. The first power component P1 includes a fluctuating component of the renewable energy-based electricity.

[0066] According to one aspect of the present disclosure, a power control device 1, a power control method, and a power control program, electricity based on renewable energy is separated into a first power component P1 and a second power component P2. The first power component P1, including a fluctuating component, is supplied to a heat generator 9, and the second power component P2 is supplied to a cell stack 17. Before steam is supplied to the cell stack 17, the thermal energy generated using the first power component P1 is stored in a heat storage device 10. The heat storage device 10 functions as a buffer, which can mitigate fluctuations in the output of electricity based on renewable energy. As a result, SOEC can follow fluctuations in the output of electricity based on renewable energy.

[0067] The first power component P1 includes the first fluctuating component of electricity based on renewable energy. The second power component P2 includes the second fluctuating component of electricity based on renewable energy. The frequency of the first fluctuating component is higher than the frequency of the second fluctuating component. In this case, the second fluctuating component represents the long-term trend of fluctuations in electricity based on renewable energy. The first fluctuating component represents the short-term trend of fluctuations in electricity based on renewable energy. The short-term fluctuating component is consumed by the heat generator 9, while the long-term fluctuating component is consumed by the cell stack 17. This enables stable operation of the SOEC in accordance with the time-dependent fluctuations of electricity based on renewable energy.

[0068] The second power component P2 does not include the fluctuating component of electricity based on renewable energy. In this case, the second power component P2 supplied to the cell stack 17 is stable, and therefore the operation of the cell stack 17 is stable.

[0069] The heat generator 9 generates steam as thermal energy. Its power output sensitivity is low relative to the amount of steam generated. That is, even if the first power component P1 for steam generation fluctuates significantly, the amount of steam generated does not fluctuate significantly. Therefore, the heat generator 9 can efficiently mitigate power output fluctuations based on renewable energy. Furthermore, even in SOECs with a low load change rate (Ramp Rate) related to steam generation, it can cope with power fluctuations based on renewable energy.

[0070] [Modifications] This disclosure is not necessarily limited to the embodiments described above, and various modifications are possible without departing from the spirit of the disclosure.

[0071] The heat generation device 9 may be a seawater desalination plant using a multi-stage flash method or the like. The seawater desalination plant may generate steam (vaporized freshwater) as thermal energy. The heat storage device 10 may store the steam generated by the seawater desalination plant. In this case, since the pure water production device 6 and the like are not required, the equipment can be simplified and the overall efficiency of the plant can be improved.

[0072] In the above embodiment, an example was described in which the heat storage device 10 is a steam accumulator. Since the steam accumulator stores steam itself, it is possible to easily adjust the amount of steam supplied to the first heat exchanger 11 and improve the responsiveness regarding steam supply. The configuration of the heat storage device 10 is not limited to this. For example, the heat storage device 10 may store thermal energy using salt, oil, or stone as a heat storage medium. In one example, the heat storage device 10 may be a molten salt type heat storage device that heats salt using a portion of the steam generated by the heat generation device 9.

[0073] In the embodiment, the hydrogen production apparatus 2 is described as receiving renewable energy power from the connection point 4, but the disclosure is not limited thereto. In addition to the power source 3, the connection point 4 may receive power from another power source (e.g., commercial power). The connection point 4 may supply power supplied from both the power source 3 and the commercial power to the hydrogen production apparatus 2. For example, the power from the connection point 4 may consist of equal parts power from the power source 3 and power from the commercial power.

[0074] The power separation unit 5 may subtract the power required for operation from the renewable energy power before separating the renewable energy power into a first power component and a second power component. Examples of power required for operation include, but are not limited to, the power consumption of the first preheater 12, the second preheater 15, the control panel (not shown), and the air conditioning equipment (not shown).

[0075] For example, if the renewable energy source is sunlight, and it is sunrise, sunset, or a cloudy day, the renewable energy power may not be large enough to operate the SOEC. In this case, the power separation unit 5 may control the system to supply all of the renewable energy power to the heat generator 9. The power separation unit 5 may also set the power supply to the rectifier 16 to zero. For example, the power separation unit 5 separates the renewable energy power into a first power component P1 and a second power component P2. The power separation unit 5 may also determine whether the second power component P2 meets the criteria (threshold) for operating the cell stack 17. If the criteria are not met, the power separation unit 5 may control the system to supply both the first power component P1 and the second power component P2 to the heat generator 9. In this case, instability in the operation of the cell stack 17 can be avoided. In addition, thermal energy can be stored in advance in the heat storage device 10. As a result, the operation of the SOEC becomes more stable.

[0076] In order to achieve a predetermined amount of electrical energy [kWh] in a predetermined time, the connection point 4 may be provided with a control function that adjusts the power supplied to the heat generator 9 and the power supplied to the rectifier 16.

[0077] [Note] The power control device, power control method, and power control program of this disclosure enable SOEC to track fluctuations in the output of renewable energy-based electricity. Therefore, the power control device, power control method, and power control program of this disclosure contribute to Target 7-2 of the United Nations Sustainable Development Goals (SDGs).

[0078] Target 7-2 states, "By 2030, significantly increase the proportion of renewable energy used in energy production."

[0079] The gist of this disclosure is as follows: [1] A power control device for controlling the power supply of an SOEC using electricity based on renewable energy, comprising: a power separation unit for separating the electricity based on renewable energy into a first power component and a second power component; a heat generation device for generating thermal energy using the first power component; a heat storage device for storing the thermal energy and outputting steam; and a cell stack for generating hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy. [2] The power control device according to [1], wherein the first power component includes a first fluctuating component of the electricity based on renewable energy, the second power component includes a second fluctuating component of the electricity based on renewable energy, and the frequency of the first fluctuating component is higher than the frequency of the second fluctuating component. [3] The power control device according to [1] or [2], wherein the second power component does not include a fluctuating component of the electricity based on renewable energy. [4] The power control device according to any one of [1] to [3], wherein the heat generation device generates steam as thermal energy. [5] The power control device according to any one of [1] to [4], wherein the power separation unit determines whether the second power component meets the criteria for operating the cell stack, and if the criteria are not met, controls the supply of the first power component and the second power component to the heat generating device. [6] A power control method performed by a power control device that controls the power supply of an SOEC using electricity based on renewable energy, comprising: a step of separating the electricity based on renewable energy into a first power component and a second power component; a step of generating thermal energy using the first power component; a step of storing the thermal energy and outputting steam; and a step of generating hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy.[7] A power control program for controlling the power supply of an SOEC using electricity based on renewable energy, wherein the program causes a computer to perform the following steps: separating the electricity based on renewable energy into a first power component and a second power component; generating thermal energy using the first power component; storing the thermal energy and outputting steam; and generating hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy.

[0080] 1 Power control device 2 Hydrogen production device 5 Power separation unit 4 Connection point 3 Power source 6 Pure water production device 7 Pure water tank 8 Pump 9 Heat generation device 10 Heat storage device 11 First heat exchanger 12 First preheater 13 Blower 14 Second heat exchanger 15 Second preheater 16 Rectifier 17 Cell stack 18 Cooler 19 Gas-liquid separator 20 Compressor 100 Computer 110 Program P1 First power component P2 Second power component

Claims

1. A power control device for controlling the power supply of a Solid Oxide Electrolyzer Cell (SOEC) using electricity based on renewable energy, comprising: a power separation unit that separates the electricity based on renewable energy into a first power component and a second power component; a heat generation device that generates thermal energy using the first power component; a heat storage device that stores the thermal energy and outputs steam; and a cell stack that generates hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy.

2. The power control device according to claim 1, wherein the first power component includes a first fluctuating component of the electricity based on the renewable energy, the second power component includes a second fluctuating component of the electricity based on the renewable energy, and the frequency of the first fluctuating component is higher than the frequency of the second fluctuating component.

3. The power control device according to claim 1, wherein the second power component does not include the fluctuating component of the power based on the renewable energy.

4. The power control device according to claim 1, wherein the heat generating device generates steam as thermal energy.

5. The power control device according to claim 1, wherein the power separation unit determines whether the second power component meets the criteria for operating the cell stack, and if the criteria are not met, controls the supply of the first power component and the second power component to the heat generating device.

6. A power control method performed by a power control device that controls the power supply of an SOEC using electricity based on renewable energy, comprising: a step of separating the electricity based on renewable energy into a first power component and a second power component; a step of generating thermal energy using the first power component; a step of storing the thermal energy and outputting steam; and a step of generating hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy.

7. A power control program for controlling the power supply of an SOEC using electricity based on renewable energy, wherein the program causes a computer to perform the following steps: separating the electricity based on renewable energy into a first power component and a second power component; generating thermal energy using the first power component; storing the thermal energy and outputting steam; and generating hydrogen using the second power component and the steam, wherein the first power component includes a fluctuating component of the electricity based on renewable energy.

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