Management device, management method, and management program

Abstract

This management device according to one embodiment comprises a green degree calculation unit. The green degree calculation unit calculates, as a green degree expressing the environmental contribution of hydrogen, the ratio of a renewable energy power amount to a power amount supplied only to a water electrolysis cell for generating hydrogen by water electrolysis using the supplied power. The green degree calculation unit outputs the green degree.

Description

Management device, management method, and management program

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

[0002] Hydrogen energy is attracting attention as a way to realize a carbon-neutral society. Currently, hydrogen used as an energy source is produced by reforming fossil fuels. The method of reforming fossil fuels produces a large amount of carbon dioxide (CO ２ ) is generated. Here, CO generated in the method of reforming fossil fuels ２ However, in the method of reforming fossil fuels, CO is generated during the production of hydrogen. ２ The occurrence of this problem is not prevented.

[0003] In recent years, methods for producing hydrogen by electrolysis of water using renewable energy have been investigated. In principle, hydrogen production using renewable energy does not require CO ２ For this reason, hydrogen produced using renewable energy is sometimes called "green hydrogen."

[0004] In reality, it is not realistic to produce hydrogen solely from renewable energy sources, and it may become necessary to purchase the necessary electricity from electric power companies, etc. In this case, it is expected that electricity from renewable energy sources and electricity from non-renewable energy sources will be mixed when producing hydrogen. Hydrogen produced using a mixture of electricity from renewable and non-renewable energy sources cannot be called green hydrogen. Therefore, evaluating the greenness of the hydrogen produced is important in order to guarantee the quality of the hydrogen produced.

[0005] Japanese Patent Application Publication No. 2023-085130

[0006] The present disclosure provides a management device, a management method, and a management program for evaluating the greenness of produced hydrogen.

[0007] The management device of one aspect includes a green index calculation unit that calculates a ratio of the amount of renewable energy power input to a water electrolysis cell that generates hydrogen by electrolyzing water using the input power as a green index that represents the degree of contribution of hydrogen to the environment, and outputs the green index.

[0008] According to the present disclosure, it is possible to provide a management device, a management method, and a management program for evaluating the greenness of hydrogen produced.

[0009] FIG. 1 is a diagram showing the configuration of an example of a hydrogen production system according to an embodiment. FIG. 2 is a block diagram showing the configuration of an example of a water electrolysis device. FIG. 3 is a diagram showing the hardware configuration of an example of a management device. FIG. 4 is a flowchart showing the operation of the management device according to an embodiment. FIG. 5 is a conceptual diagram showing calculation of a green index. FIG. 6 is a diagram showing an example of a concept of an optimal operation plan when power stored in a storage battery is not used. FIG. 7 is a diagram showing an example of a concept of an optimal operation plan when power stored in a storage battery is used. FIG. 8 is a diagram showing the configuration of an example of a hydrogen production system according to a modified example of the embodiment. FIG. 9 is a flowchart showing the operation of the management device according to the modified example.

[0010] Hereinafter, an embodiment will be described with reference to the drawings. Fig. 1 is a diagram showing the configuration of an example of a hydrogen production system according to an embodiment. The hydrogen production system 1 includes a water electrolysis facility 2, a power supply facility 3, and a management device 4. The management device 4 is connected to a hydrogen sales management device 5 via data communication. The hydrogen sales management device 5 is, for example, a computer that manages the sales price of hydrogen produced in the water electrolysis facility 2.

[0011] The water electrolysis facility 2 is a facility for producing hydrogen by water electrolysis. The water electrolysis facility 2 operates based on an operation plan from a management device 4. The water electrolysis facility 2 also periodically transmits operation data to the management device 4. The water electrolysis facility 2 includes a control device 21, a water electrolysis device 22, and a storage battery 23. The control device 21 is configured to be able to communicate data with the water electrolysis device 22 and the storage battery 23.

[0012] The control device 21 is a computer equipped with a processor, memory, etc., and controls the operation of the water electrolysis device 22 and the operation of the storage battery 23. For example, the control device 21 operates the water electrolysis device 22 based on an operation plan received from the management device 4. The control device 21 also measures the state of the water electrolysis device 22 and the state of the storage battery 23, and sends data indicating the measured state of the water electrolysis device 22 and the state of the storage battery 23 to the management device 4 as operation data. The state of the water electrolysis device 22 includes the amount of power consumed by the water electrolysis device 22. The state of the storage battery 23 includes the amount of charge and discharge. In addition, the state of the water electrolysis device 22 may also include the location of the water electrolysis device 22 and the state of the surrounding environment, such as the ambient temperature.

[0013] The water electrolysis apparatus 22 is an apparatus for producing hydrogen by water electrolysis. Fig. 2 is a block diagram showing the configuration of an example water electrolysis apparatus, for example, a water electrolysis apparatus having an alkaline electrolysis cell. The water electrolysis apparatus 22 includes an electrolytic cell 2201, an anolyte circulation tank 2202, a catholyte circulation tank 2203, an electrolyte circulation pump 2204, an electrolyte cooler 2205, a mist separator 2206, a scrubbing tower 2207, a candle filter 2208, a buffer tank 2209, a compressor 2210, a hydrogen gas purification apparatus 2211, a mist separator 2212, a scrubbing tower 2213, a candle filter 2214, and an oxygen gas seal pot 2215. Of these components, the elements other than the electrolytic cell 2201 are auxiliary equipment of the water electrolysis apparatus 22.

[0014] The electrolytic cell 2201 is supplied with power from the power supply facility 3 and circulates water (H ２ O) to hydrogen (H ２ ) and oxygen (O ２ ) and the electrolytic cell 2201. Here, the electrolytic cell 2201 does not have to be an alkaline water electrolysis cell, and may be a water electrolysis cell of a solid polymer electrolyte membrane (PEM) type, an anion exchange membrane (AEM) type, a solid oxide electrolyte (SOEC) type, or the like. Depending on the configuration of the electrolytic cell 2201, the auxiliary equipment will have a configuration different from that shown in FIG. 2.

[0015] The anolyte circulation tank 2202 is a tank that stores the electrolyte separated from the oxygen gas in the mist separator 2212. When the water electrolysis device 22 is in operation, the electrolyte is sent from the anolyte circulation tank 2202 to the electrolytic cell 2201 by the electrolyte circulation pump 2204.

[0016] The catholyte circulation tank 2203 is a tank that stores the electrolyte separated from the hydrogen gas in the mist separator 2206. When the water electrolysis device 22 is in operation, the electrolyte circulation pump 2204 sends the electrolyte from the catholyte circulation tank 2203 to the electrolytic cell 2201.

[0017] The electrolyte circulation pump 2204 is a pump for circulating the electrolyte in the water electrolysis apparatus 22. When the electrolyte circulation pump 2204 is operated, the electrolyte is sent from the anolyte circulation tank 2202 and the catholyte circulation tank 2203 to the electrolytic cell 2201.

[0018] The electrolyte cooler 2205 is provided between the electrolyte circulation pump 2204 and the electrolytic cell 2201. The electrolyte cooler 2205 cools the electrolyte that is sent to the electrolytic cell 2201 by the electrolyte circulation pump 2204.

[0019] The mist separator 2206 separates the electrolyte from the hydrogen gas containing the electrolyte generated at the cathode of the electrolytic cell 2201. The hydrogen gas separated by the mist separator 2206 is sent to a scrubbing tower 2207. Meanwhile, the electrolyte separated by the mist separator 2206 is sent to a catholyte circulation tank 2203. The electrolyte sent to the catholyte circulation tank 2203 is used for the next and subsequent water electrolysis.

[0020] The scrubbing tower 2207 scrubs impurities from the hydrogen gas sent from the mist separator 2206. The candle filter 2208 further filters the hydrogen gas scrubbed in the scrubbing tower 2207.

[0021] The buffer tank 2209 is a tank for temporarily storing the hydrogen gas that has passed through the candle filter 2208 .

[0022] The compressor 2210 compresses the hydrogen gas stored in the buffer tank 2209 to a predetermined high pressure for storage.

[0023] The hydrogen gas purification device 2211 purifies high-purity hydrogen gas from the high-pressure hydrogen gas compressed by the compressor 2210. The hydrogen produced by the hydrogen gas purification device 2211 is stored in a hydrogen storage and supply device (not shown). Here, the hydrogen storage and supply device may be configured to store hydrogen classified according to the greenness level, which will be described later.

[0024] The mist separator 2212 separates the electrolyte from the oxygen gas containing the electrolyte generated at the anode of the electrolytic cell 2201. The oxygen gas separated by the mist separator 2212 is sent to a scrubbing tower 2213. Meanwhile, the electrolyte separated by the mist separator 2212 is sent to the anolyte circulation tank 2202. The electrolyte sent to the anolyte circulation tank 2202 is used for the next and subsequent water electrolysis.

[0025] The scrubbing tower 2213 scrubs impurities from the oxygen gas sent from the mist separator 2212. The candle filter 2214 further filters the oxygen gas scrubbed in the scrubbing tower 2213.

[0026] The oxygen gas seal pot 2215 returns the pressure of the oxygen gas to atmospheric pressure while using a liquid to seal the oxygen gas that has passed through the candle filter 2214. The oxygen gas that has been returned to atmospheric pressure in the oxygen gas seal pot 2215 is released into the atmosphere.

[0027] Returning now to the description of Fig. 1, the storage battery 23 is, for example, a lithium-ion storage battery. Under the control of the control device 21, the storage battery 23 performs a charging operation in accordance with the power supplied from the power supply facility 3 and supplies power to the water electrolysis device 22. The storage battery 23 is not limited to a lithium-ion storage battery, and may be any storage battery, such as a nickel-metal hydride battery or a lead-acid battery.

[0028] The power supply facility 3 is a facility that supplies power to the water electrolysis facility 2. In the embodiment, the power supply facility 3 includes a self-owned renewable energy (renewable energy) supply facility 31, a self-owned renewable energy (renewable energy) supply facility 32, and a grid power supply facility 33. Note that the power supply facility 3 does not necessarily have to include all of the self-owned renewable energy supply facility 31, the self-owned renewable energy supply facility 32, and the grid power supply facility 33. For example, the power supply facility 3 does not necessarily have to include the self-owned renewable energy supply facility 31.

[0029] The self-owned renewable energy supply facility 31 is a renewable energy supply facility under the management of the water electrolysis facility 2, and is a facility that supplies power to the water electrolysis facility 2 without going through a grid power transmission line laid by an electric power company or the like. For example, the self-owned renewable energy supply facility 31 is a power generation facility located in the same facility as the water electrolysis facility 2. Renewable energy does not emit CO ２ This energy is generated by various types of solar power generation facilities, wind power generation facilities, geothermal power generation facilities, hydroelectric power generation facilities, biomass power generation facilities, etc. that do not emit CO2.

[0030] The self-owned renewable energy supply facility 32 is a renewable energy supply facility under the management of the water electrolysis facility 2, and supplies power to the water electrolysis facility 2 via a grid transmission line laid by an electric power company or the like. For example, the self-owned renewable energy supply facility 32 is a power generation facility located remotely from the facility where the water electrolysis facility 2 is located. Power transmission from the self-owned renewable energy supply facility 32 is managed by an aggregator or the like in accordance with a power purchase agreement (PPA). The aggregator or the like issues a demand response (DR) command to the self-owned renewable energy supply facility 32 in response to a request from the water electrolysis facility 2, causing the self-owned renewable energy supply facility 32 to transmit power.

[0031] The grid power supply facility 33 is a power supply facility provided by an electric power company or the like. The grid power supply facility 33 may or may not include a renewable energy supply facility. Examples of power supply facilities for non-renewable energy sources include thermal power generation facilities.

[0032] The management device 4 is a computer that manages hydrogen production in the water electrolysis facility 2 while collecting data from the water electrolysis facility 2 and the power supply facility 3. Specifically, the management of hydrogen production includes management of hydrogen quality and management of the availability of the water electrolysis facility 2. The availability of the water electrolysis facility 2 may be the same as the availability of the water electrolysis cells. Here, the management device 4 may be located in the same facility as the water electrolysis facility 2, or in a different facility.

[0033] The management device 4 in the embodiment includes a database (DB) 41 , a power generation amount prediction unit 42 , a greenness index calculation unit 43 , and an operation plan determination unit 44 .

[0034] The DB 41 stores data used for various processes in the management device 4. The DB 41 stores, for example, renewable energy power generation amount record data 411, weather record data 412, demand record data 413, and operation record data 414.

[0035] The renewable energy power generation amount record data 411 is record data for a predetermined period of time, for example, every 30 minutes, of the amount of power generated by the private renewable energy supply facility 31. The renewable energy power generation amount record data 411 can be collected from the private renewable energy supply facility 31.

[0036] The weather record data 412 is record data of the weather at the private renewable energy supply facility 31, the private renewable energy supply facility 32, and the grid power supply facility 33 for a predetermined period of time, for example, every 30 minutes. For example, if the power generation facility includes a solar power generation facility, the weather may include data on the hours of sunshine. Furthermore, if the power generation facility includes a wind power generation facility, the weather may include data on wind speed and wind direction. The weather record data 412 may be collected, for example, from each of the private renewable energy supply facility 31, the private renewable energy supply facility 32, and the grid power supply facility 33, or may be collected from a weather forecast site or the like. Furthermore, if the management device 4 is equipped with a weather forecast model for making predictions, the weather record data 412 does not need to be stored in the DB 41. On the other hand, the weather record data 412 may be stored in the DB 41 to be used for training the weather forecast model.

[0037] The demand record data 413 is record data of the amount of power demanded in the water electrolysis facility 2 for a predetermined period of time, for example, every 30 minutes. The demand record data 413 can be collected from the water electrolysis facility 2, for example.

[0038] The operation history data 414 is data on the operation history of the grid power supply facility 33 for a predetermined time period, for example, every 30 minutes. The operation history represents the power supply configuration of the grid power supply facility 33. For example, if the grid power supply facility 33 includes a photovoltaic power generation facility, a hydroelectric power generation facility, and a thermal power generation facility, the operation history data 414 is data on the amount of power generated by each of the photovoltaic power generation facility, the hydroelectric power generation facility, and the thermal power generation facility. The operation history data 414 can be collected from the grid power supply facility 33.

[0039] The power generation amount prediction unit 42 predicts the amount of power generated by the power supply facility 3. The power generation amount prediction unit 42 includes a self-power generation amount prediction unit 421 and a grid power generation amount prediction unit 422.

[0040] The self-owned power generation amount prediction unit 421 is a prediction model that predicts the amount of power generated by the self-owned renewable energy supply facility 31. The self-owned power generation amount prediction unit 421 also predicts the amount of power generated by the self-owned renewable energy supply facility 32.

[0041] The self-owned power generation amount prediction unit 421 predicts the amount of power generated by the self-owned renewable energy supply facility 31 per unit time, for example, every 30 minutes, using, for example, a self-owned power generation amount prediction model. The self-owned power generation amount prediction model is a machine learning model configured to input environmental data related to the amount of power generated by the self-owned renewable energy supply facility 31, such as weather, and output a prediction result of the amount of power generated by the self-owned renewable energy supply facility 31. The renewable energy power generation amount record data 411 and the weather record data 412 may be used to train the self-owned power generation amount prediction model. Alternatively, the self-owned power generation amount prediction unit 421 may predict the amount of power generated by the self-owned renewable energy supply facility 31 by collecting environmental measurement data related to the amount of power generated by the self-owned renewable energy supply facility 31 from the self-owned renewable energy supply facility 31, etc.

[0042] Furthermore, the self-owned power generation amount prediction unit 421 predicts the amount of power generated by the self-owned renewable energy supply facility 32 per unit time, for example, every 30 minutes, from the amount of power purchased based on the PPA for the self-owned renewable energy supply facility 32. Alternatively, the self-owned power generation amount prediction unit 421 may predict the amount of power generated by the self-owned renewable energy supply facility 32 using, for example, a self-owned power generation amount prediction model, or may predict the amount of power generated by the self-owned renewable energy supply facility 32 by collecting environmental measurement data related to the amount of power generated by the self-owned renewable energy supply facility 32 from the self-owned renewable energy supply facility 32, etc.

[0043] The grid power generation amount prediction unit 422 predicts the amount of power generated by the grid power supply facility 33 per unit time, for example, every 30 minutes. The amount of power generated by the grid power supply facility 33 is the amount of power generated by each power supply facility of the grid power supply facility 33. For example, if the grid power supply facility 33 includes a solar power generation facility, a hydroelectric power generation facility, and a thermal power generation facility, the amount of power generated by the grid power supply facility 33 is the amount of power generated by each of the solar power generation facility, the hydroelectric power generation facility, and the thermal power generation facility. The grid power generation amount prediction unit 422 predicts the amount of power generated by the grid power supply facility 33, for example, using a grid power generation amount prediction model. The grid power generation amount prediction model is a machine learning model configured to input environmental data related to the amount of power generated by the grid power supply facility 33, such as weather, and output a prediction result of the amount of power generated by the grid power supply facility 33. The operation record data 414 and the weather record data 412 can be used to train the grid power generation amount prediction model.

[0044] The greenness calculation unit 43 calculates the greenness of hydrogen produced in the water electrolysis facility 2. The greenness (G-degree) is one of the indicators that represent the quality of produced hydrogen, and indicates the degree to which the produced hydrogen contributes to the environment. In this embodiment, the greenness is the "proportion of renewable energy in the electric power input to the electrolysis cells 2201 of the water electrolysis facility 2, i.e., the electric power input only to the water electrolysis cells." Here, in this embodiment, the electric power input to the auxiliary machinery of the water electrolysis facility 2 does not need to be taken into consideration in calculating the greenness. This is because only the water electrolysis cells are directly involved in water electrolysis.

[0045] In the embodiment, the green degree G (%) can be calculated from the following formula (1) where P1 (kWh) is the average power generation amount per unit time, for example, 30 minutes, of the private renewable energy supply facility 31, P2 (kWh) is the average power generation amount per unit time of the private renewable energy supply facility 32, P3 (kWh) is the average power generation amount per unit time of renewable energy in the grid power supply facility 33, P4 (kWh) is the average power generation amount per unit time of non-renewable energy in the grid power supply facility 33, P5 is the renewable energy portion of the power supplied from the storage battery 23, and P6 is the non-renewable energy portion of the power supplied from the storage battery 23: G=(P1+P2+P3+P5) / (P1+P2+P3+P4+P5+P6)×100(%) (1) For example, if the only power input to the water electrolysis cell is power generated by the private renewable energy supply facility 31 and / or the private renewable energy supply facility 32, the green degree is 100%. On the other hand, for example, if the electricity input to the water electrolysis cell includes electricity generated by the grid power supply facility 33, the green level will be 100% or less depending on the composition ratio of renewable energy and non-renewable energy in the electricity generated by the grid power supply facility 33.

[0046] In this manner, in the embodiment, CO 2 which is expected to be emitted during the production of hydrogen ２ By defining greenness as the proportion of renewable energy in the electricity input to a water electrolysis cell, rather than the basic unit, the environmental contribution of hydrogen produced using electricity can be accurately and appropriately evaluated.

[0047] The operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2. The operation plan for the water electrolysis equipment 2 includes a condition for the availability of the water electrolysis equipment 2 and a condition for the composition of power input to the water electrolysis cells. The operation plan is determined based on various conditions, such as the amount of power generated by the power supply equipment 3, the selling price of electricity, the power demand at the water electrolysis equipment 2, and the green level required for the hydrogen to be produced. The operation plan determination unit 44 includes, for example, an operation simulator 441 for the water electrolysis equipment 2. The operation plan determination unit 44 inputs various parameters into the operation simulator 441 to perform an operation simulation of the water electrolysis equipment 2 and determine an optimal operation plan for the water electrolysis equipment 2 that satisfies desired conditions.

[0048] Next, a description will be given of an example of the hardware configuration of the management device 4. Fig. 3 is a diagram showing an example of the hardware configuration of the management device 4. As shown in Fig. 3, the management device 4 is a computer having a processor 401, an input device 402, a display device 403, a communication device 404, a memory 405, and a storage 406. The processor 401, the input device 402, the display device 403, the communication device 404, the memory 405, and the storage 406 are connected via a bus 407.

[0049] The processor 401 controls the overall operation of the management device 4. The processor 401 operates as the power generation amount prediction unit 42, the greenness index calculation unit 43, and the operation plan determination unit 44 by executing, for example, a management program 4061 stored in the storage 406. The processor 401 is, for example, a CPU. The processor 401 may be an MPU, a GPU, an ASIC, an FPGA, or the like. The processor 401 may be a single CPU or the like, or may be multiple CPUs or the like.

[0050] The input device 402 includes an input device such as a keyboard, a mouse, or a touch panel. When the input device is operated, a signal corresponding to the operation is input to the processor 401 via the bus 407. The processor 401 performs various processes in response to this signal. The input device 402 is used to input, for example, a target value for the greenness of hydrogen and a target value for the availability of the water electrolysis equipment 2.

[0051] The display device 403 is a display such as a liquid crystal display or an organic EL display. The display device 403 can be used to notify the user of the management device 4 of, for example, the calculation results of the greenness index, the determination results of the operation plan for the water electrolysis equipment 2, etc.

[0052] The communication device 404 is a device that enables the management device 4 to communicate with external facilities. The external facilities are the water electrolysis facility 2, the private renewable energy supply facility 31, the private renewable energy supply facility 32, and the grid power supply facility 33. The communication device 404 may be a communication device for wired communication or a communication device for wireless communication.

[0053] The memory 405 includes a ROM and a RAM. The ROM is a non-volatile memory. The ROM stores a startup program for the management device 4 and the like. The RAM is a volatile memory. The RAM is used as a working memory for processing by the processor 401, for example.

[0054] The storage 406 is, for example, a storage such as a hard disk drive or a solid state drive. The storage 406 stores various programs executed by the processor 401, such as a management program 4061. The storage 406 may also store a DB 4062, a self-power generation amount prediction model 4063, a grid power generation amount prediction model 4064, and an operation simulator 4065. The DB 4062 corresponds to the DB 41, and stores, for example, renewable energy power generation amount record data 411, weather record data 412, demand record data 413, and operation record data 414. The self-power generation amount prediction model 4063 is a machine learning model configured to input environmental data related to the power generation amount of the self-owned renewable energy supply facility 31 and output a prediction result of the power generation amount of the self-owned renewable energy supply facility 31. The grid power generation amount prediction model 4064 is a machine learning model configured to receive environmental data related to the amount of power generated by the grid power supply facility 33 as input and output a prediction result of the amount of power generated by the grid power supply facility 33. The operation simulator 4065 corresponds to the operation simulator 441 and is a simulator used to determine an optimal operation plan for the water electrolysis facility 2. The DB 4062, the self-power generation amount prediction model 4063, the grid power generation amount prediction model 4064, and the operation simulator 4065 may be stored in a server or the like that can communicate with the management device 4. In this case, the management device 4 transmits and receives necessary data to and from the server using the communication device 404.

[0055] Next, a description will be given of the operation of the management device 4. Fig. 4 is a flowchart showing the operation of the management device 4. The operation of Fig. 4 is performed at regular intervals, for example, every morning of each day or every morning of one week.

[0056] In step S1, the power generation amount prediction unit 42 predicts the amount of power generated by the self-owned renewable energy supply facility 31 and / or the self-owned renewable energy supply facility 32. The power generation amount prediction unit 42 predicts the amount of power generated by each self-owned renewable energy supply facility 31 on the target day for determining the operation plan by inputting environmental data such as the weather on the target day for determining the operation plan into the self-owned renewable energy supply amount prediction model. In addition, the power generation amount prediction unit 42 predicts the amount of power generated by each self-owned renewable energy supply facility 32 on the target day for determining the operation plan from the purchase history based on the PPA.

[0057] In step S2, the power generation amount prediction unit 42 predicts the amount of power generated by the grid power supply facility 33. The power generation amount prediction unit 42 predicts the amount of power generated by each grid power supply facility 33 on the day for which the operation plan is to be determined by inputting environmental data such as the weather on the day for which the operation plan is to be determined into a grid power generation amount prediction model.

[0058] In step S3, the greenness index calculation unit 43 calculates the greenness index for the day on which the operation plan is to be determined, without taking the storage battery 23 into consideration, based on the power demand of the water electrolysis equipment 2 for the day on which the operation plan is to be determined and the predicted power generation amount by the power generation amount prediction unit 42. The calculation of the greenness index will be described below.

[0059] Figure 5 is a conceptual diagram showing how the greenness index is calculated. The horizontal axis in Figure 5 represents elapsed time (min). For example, one division on the horizontal axis represents 30 minutes, and the scale covers approximately one day from dawn to night. On the other hand, the vertical axis in Figure 5 represents the amount of power generated (kWh).

[0060] Here, the self-owned renewable energy supply facility is assumed to be a solar power generation facility. In this case, the power generation amount of the self-owned renewable energy supply facility, shown as "Self-owned renewable energy amount" in Figure 5, shows an approximately Gaussian distribution type variation that reaches a maximum value around daytime. "Self-owned renewable energy amount" in Figure 5 is the sum of P1 and P2 in Equation (1).

[0061] The vertical axis of FIG. 5 represents the "power demand" required by the water electrolysis cells of the water electrolysis equipment 2. For example, when the "self-sponsored renewable energy amount" is equal to or greater than the "100% power demand," such as during the daytime, the water electrolysis cells can operate at 100% availability using only the power from the self-sponsored renewable energy supply equipment. In this case, the green index G is 100% because P3, P4, P5, and P6 in formula (1) are 0 (kWh). In reality, power is also required by the auxiliary equipment of the water electrolysis equipment 2. However, the power required by the auxiliary equipment of the water electrolysis equipment 2 may be supplied by the "self-sponsored renewable energy amount" that exceeds the "100% power demand" or by non-renewable energy input from the grid power supply equipment. In this embodiment, the green index G is calculated to be 100% even when the "self-sponsored renewable energy amount" that exceeds the "100% power demand" is less than the "power demand of the auxiliary equipment."

[0062] The above is the calculation of the greenness index when power can be supplied only by the self-owned renewable energy supply facility 31 and the self-owned renewable energy supply facility 32. In reality, the renewable energy input from the grid power supply facility indicated by the "grid renewable energy amount" can be added to the "self-owned renewable energy amount." When the "total renewable energy amount," which is the sum of the "self-owned renewable energy amount" and the "grid renewable energy amount," is equal to or greater than "100% of the power demand," this indicates that the water electrolysis cell can operate at 100% availability using only renewable energy. In this case, the greenness index G is also 100% because P4, P5, and P6 in formula (1) are 0 (kWh).

[0063] On the other hand, when the "total renewable energy amount" is less than "100% of the demand amount," such as at dawn or at night, the shortfall is made up by non-renewable energy input from the grid power supply facility. In this case, P4 in formula (1) is no longer 0 (kWh), and the green degree G becomes less than 100%.

[0064] In this way, the greenness index G for each time period is calculated from only the predicted amount of power for each facility. Figure 5 shows the greenness index for each time period. With a constant target operating rate, the greenness index will be high during time periods when the "total amount of renewable energy" is large, such as during the day, and low during time periods when the "total amount of renewable energy" is small, such as at dawn and at night. Here, Figure 5 shows the greenness index for approximately one day. Similar calculations of the greenness index may be performed for multiple days included in the target date for determining the operation plan.

[0065] Returning to the description of FIG. 4 , in step S4, the operation plan determination unit 44 determines whether to determine an operation plan that prioritizes greenness. As described above, if the operation rate of the electrolysis cell is always set to 100%, the greenness will be small during the time period when the shortage is compensated for by non-renewable energy input from the grid power supply facility. On the other hand, if the "operation rate of the electrolysis cell" is set so as not to exceed the "total renewable energy amount," the greenness will be maintained at 100%. In other words, in this embodiment, there is a trade-off between the greenness of hydrogen and the operation rate of the electrolysis cell. In step S4, it is determined whether to prioritize the greenness of hydrogen or the operation rate of the electrolysis cell. This determination may be made, for example, based on input from the user of the management device 4. For example, if the user of the management device 4 inputs a target value for the greenness of hydrogen, it is determined to determine an operation plan that prioritizes greenness. However, if the user of the management device 4 inputs a target value for the operation rate of the water electrolysis facility 2, it is determined to determine an operation plan that prioritizes operation rate. If it is determined in step S4 that an operation plan that prioritizes greenness should be determined, the process proceeds to step S5. If it is determined in step S4 that an operation plan that prioritizes availability should be determined, the process proceeds to step S10.

[0066] In step S5, the operation plan determination unit 44 determines whether to use the storage battery 23 when operating the water electrolysis cell. As described above, when the "total renewable energy amount" is less than "100% of the demanded power amount," the shortfall is basically made up by non-renewable energy input from the grid power supply facility. However, this shortfall can also be made up by power supplied from the storage battery 23. However, as will be described later, the storage battery 23 is charged with surplus power relative to the power corresponding to the required operating rate of the water electrolysis cell. Therefore, the power stored in the storage battery 23 may be a mixture of power from renewable energy and power from non-renewable energy. In other words, use of the storage battery 23 may also reduce the greenness of hydrogen. Therefore, in this embodiment, the determination of whether to use the storage battery 23 when operating the water electrolysis cell is made based on, for example, a user input. If it is determined in step S5 that the storage battery 23 will not be used when operating the water electrolysis cell, the process proceeds to step S6. If it is determined in step S5 that the storage battery 23 is to be used in operating the water electrolysis cell, the process proceeds to step S7.

[0067] In step S6, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so as to achieve the target value of the greenness index without using the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters including the target value of the greenness index into an operation simulator.

[0068] FIG. 6 is a diagram illustrating an example of an optimal operation plan when the power stored in the storage battery 23 is not used. FIG. 6 illustrates an example in which the target greenness value is 100%. As illustrated in FIG. 6 , when the "total renewable energy amount" is equal to or greater than "100% power demand," such as during the daytime, the water electrolysis cell can operate at 100% capacity using only renewable energy. In this case, an operation plan is determined that includes power requests for the private renewable energy supply facility 31, the private renewable energy supply facility 32, and the grid power supply facility 33 so that the water electrolysis cell operates at 100% capacity. Here, power may be requested to exceed "100% power demand," and the power exceeding "100% power demand" may be used as power for auxiliary equipment of the water electrolysis facility 2 or to charge the storage battery 23. Furthermore, the power exceeding "100% power demand" may include non-renewable energy from the grid power supply facility 33.

[0069] On the other hand, when the "total renewable energy amount" is less than "100% of the demanded power amount," such as at dawn or at night, if the electrolysis cells operate at 100% capacity, the target greenness level will not be achieved. In this case, an operation plan is determined that includes the requested power for the self-owned renewable energy supply facility 31, the self-owned renewable energy supply facility 32, and the grid power supply facility 33, so that the "set demanded power amount" does not exceed the "total renewable energy amount." Here, power may be requested to exceed the "set demanded power amount," and the power exceeding the "set demanded power amount" may be used as power for the auxiliary equipment of the water electrolysis facility 2 or may be used to charge the storage battery 23. Furthermore, the power exceeding the "set demanded power amount" may include non-renewable energy of the grid power supply facility 33.

[0070] Returning now to the description of Fig. 4, in step S7, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so that the target greenness index can be achieved while utilizing the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters, including the target greenness index and the remaining capacity of the storage battery 23, into an operation simulator.

[0071] FIG. 7 is a diagram showing an example of the concept of an optimal operation plan when using power stored in the storage battery 23. FIG. 7 illustrates an example in which the target greenness value is 100%. As in FIG. 6 , FIG. 7 also illustrates that when the "total renewable energy amount" is equal to or greater than "100% power demand," such as during the daytime, the water electrolysis cell can operate at 100% capacity using only renewable energy. In this case, an operation plan is determined that includes the power demands on the private renewable energy supply facility 31, the private renewable energy supply facility 32, and the grid power supply facility 33 so that the water electrolysis cell operates at 100% capacity. Here, power demands may be made to exceed "100% power demand," and the power exceeding "100% power demand" may be used as power for the auxiliary equipment of the water electrolysis facility 2 or may be used to charge the storage battery 23. In FIG. 7 , power purchased from the grid power supply facility 33 for charging the storage battery 23 is illustrated as "additional purchase of grid power for battery charging." This additional purchased amount of electricity may include renewable energy and non-renewable energy. The composition ratio of renewable energy to non-renewable energy may be calculated from the predicted power generation amount of the grid power supply facility 33.

[0072] On the other hand, when the "total renewable energy amount" is less than "100% demand power amount," such as at dawn or at night, if the water electrolysis cell operates at 100% capacity, the target greenness level will not be achieved. In this case, an operation plan is determined that includes the power demands on the self-owned renewable energy supply facility 31, the self-owned renewable energy supply facility 32, the grid power supply facility 33, and the storage battery 23, within a range in which the "set demand power amount" does not exceed the "total renewable energy amount." As described above, the power stored in the storage battery 23 may include renewable energy and non-renewable energy. Therefore, in the case of operation prioritizing greenness, the power demand on the storage battery 23 is limited to the amount of renewable energy stored in the storage battery 23. Here, power may be requested to exceed the "set demand power amount," and the power exceeding the "set demand power amount" may be used as power for auxiliary equipment of the water electrolysis facility 2 or may be used to charge the storage battery 23. Furthermore, the amount of power exceeding the “set amount of demanded power” may include exhaustible energy of the grid power supply facility 33 .

[0073] Returning now to the description of Fig. 4 , in step S8, the operation plan determination unit 44 performs control based on the determined operation plan. Specifically, the operation plan determination unit 44 notifies the water electrolysis equipment 2 of the determined operation plan. The water electrolysis equipment 2 performs operation based on the notified operation plan.

[0074] In step S9, the greenness calculation unit 43 outputs the greenness of hydrogen produced through operation of the water electrolysis facility 2. Simply put, the greenness calculation unit 43 simply outputs the target greenness input by the management device 4. More preferably, the greenness calculation unit 43 recalculates the greenness. In this case, the greenness calculation unit 43 acquires measurement data on the amount of power generated by the private renewable energy supply facility 31, purchase data on power from the private renewable energy supply facility 32 based on the PPA, and measurement data on the amount of power generated by the grid power supply facility 33 on the target day for determining the operation plan. Furthermore, when power from the storage battery 23 is used to operate the water electrolysis facility 2, the greenness calculation unit 43 also acquires measurement data on the power consumption of the storage battery 23. The greenness calculation unit 43 then calculates the greenness for the target day for determining the operation plan based on equation (1). The greenness is likely to be output to the display device 403 of the management device 4, the hydrogen sales management device 5, or the like. When the greenness degree is output to the hydrogen sales management device 5, the hydrogen sales management device 5 can determine the selling price of hydrogen according to the greenness degree.

[0075] If it is determined in step S4 that an availability-focused operation plan should be determined, then in step S10, the operation plan determination unit 44 determines whether to use the storage battery 23 in the operation of the water electrolysis cell. As in step S5, in step S10, the determination of whether to use the storage battery 23 in the operation of the water electrolysis cell is made based on, for example, a user input. If it is determined in step S10 that the storage battery 23 will not be used in the operation of the water electrolysis cell, the process proceeds to step S11. If it is determined in step S10 that the storage battery 23 will be used in the operation of the water electrolysis cell, the process proceeds to step S12.

[0076] In step S11, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so as to achieve the target value for the availability rate without using the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters, including the target value for the availability rate, into an operation simulator. The concept of determining an operation plan when the power stored in the storage battery 23 is not used basically conforms to Fig. 6. In step S11, an operation plan is determined so as to maintain the availability rate rather than the greenness level.

[0077] In step S12, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so as to achieve the target value for the availability while utilizing the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters, including the target value for the availability and the remaining capacity of the storage battery 23, into an operation simulator. The concept of determining an operation plan when utilizing the power stored in the storage battery 23 basically conforms to Fig. 7. In step S12, an operation plan is determined so as to maintain the availability rather than the greenness level.

[0078] In step S13, the operation plan determination unit 44 performs control based on the determined operation plan. Specifically, the operation plan determination unit 44 notifies the water electrolysis equipment 2 of the determined operation plan. The water electrolysis equipment 2 performs operation based on the notified operation plan.

[0079] In step S14, the greenness index calculation unit 43 recalculates the greenness index. The method for recalculating the greenness index may be the same as the method described in step S9.

[0080] In step S15, the greenness index calculation unit 43 outputs the greenness index of the hydrogen produced through the operation of the water electrolysis equipment 2. The greenness index is likely to be output to the display device 403 of the management device 4, the hydrogen sales management device 5, or the like. When the greenness index is output to the hydrogen sales management device 5, the hydrogen sales management device 5 can determine the selling price of the hydrogen in accordance with the greenness index.

[0081] As described above, according to the embodiment, the green level of hydrogen produced by the water electrolysis facility is calculated from the proportion of renewable energy in the electricity input to the water electrolysis cell. ２ While it is relatively difficult to measure the emission intensity of hydrogen produced from renewable energy sources, the composition ratio of renewable energy sources to non-renewable energy sources in the electricity input to the water electrolysis cells alone can be calculated relatively easily and accurately. The greenness of hydrogen defined in this way is considered to be appropriate for appropriately evaluating the greenness of the hydrogen produced.

[0082] Furthermore, in the embodiment, the amount of power generated is calculated using different methods for a self-owned renewable energy supply facility that can supply power to the water electrolysis facility directly without going through a grid transmission line laid by an electric power company or the like, and a self-owned renewable energy supply facility that can supply power via a grid transmission line laid by an electric power company or the like. Specifically, for a self-owned renewable energy supply facility that can supply power via a grid transmission line laid by an electric power company or the like, the amount of power generated is calculated using power purchase data based on a PPA. In this way, the amount of power generated is calculated simply and accurately.

[0083] In the embodiment, an operation plan for the water electrolysis facility is determined based on the greenness of hydrogen produced in the water electrolysis facility and the availability of the water electrolysis facility, thereby satisfying the requirement for the greenness of the produced hydrogen or the requirement for the amount of produced hydrogen.

[0084] [Modifications] Modifications of the embodiment will be described below. First, in the embodiment, the power input to the auxiliary machinery is not taken into consideration when calculating the greenness index. On the other hand, the power input to the auxiliary machinery may also be taken into consideration when calculating the greenness index. Furthermore, when a nuclear power generation facility is included in the grid power supply facility 33, the power of the nuclear power generation facility is basically treated as non-renewable energy. On the other hand, the power of the nuclear power generation facility may also be treated as renewable energy.

[0085] In the embodiment, the operation plans are divided into an operation plan that prioritizes greenness and an operation plan that prioritizes availability. Alternatively, both the target value of greenness and the target value of availability may be input to the operation simulator to determine an optimal operation plan.

[0086] Furthermore, in the embodiment, the selling price of electricity is taken into consideration when determining the operation plan. Meanwhile, in the embodiment, the operation plan determination unit 44 determines the operation plan using various parameters so that the target value of the availability rate can be achieved. In this case, the operation plan determination unit 44 may determine the operation plan so that the target value of the availability rate can be achieved even if sufficient profits cannot be obtained by purchasing power based on a PPA from the private renewable energy supply facility 32 or purchasing power from the grid power supply facility 33. In contrast, the operation plan determination unit 44 may reset the target value of the availability rate by taking into consideration either or both of the green level and the power price, and determine the operation plan so that the reset target value can be achieved.

[0087] 8 is a diagram showing an example of the configuration of a hydrogen production system according to a modified example of the embodiment. The hydrogen production system 1 of the modified example also includes a water electrolysis facility 2, a power supply facility 3, and a management device 4. The management device 4 is connected to a hydrogen sales management device 5 via data communication. The hydrogen sales management device 5 is, for example, a computer that manages the sales price of hydrogen produced in the water electrolysis facility 2, etc.

[0088] The management device 4 of the modified example stores, in the DB 41 , renewable energy power generation record data 411 , weather record data 412 , demand record data 413 , and operation record data 414 , as well as price record data 415 .

[0089] The price performance data 415 is performance data on the electricity prices at the private renewable energy supply facility 32 and the grid power supply facility 33, as well as performance data on the selling price for each green level of produced hydrogen. The performance data on the electricity price at the private renewable energy supply facility 32 is performance data on the purchase price of renewable energy based on the PPA. On the other hand, the performance data on the electricity price at the grid power supply facility 33 is performance data on the purchase price including both renewable energy and non-renewable energy from the grid power supply facility 33. Here, the price performance data 415 may be only data on the latest purchase price and selling price.

[0090] Furthermore, the management device 4 of the modified example includes a target availability setting unit 45 in addition to the DB 41, the power generation amount prediction unit 42, the greenness degree calculation unit 43, and the operation plan determination unit 44. The target availability setting unit 45 resets the target value of the availability input by, for example, the management device 4 based on one or both of the purchase price of electricity and the sales price of hydrogen. Here, in the modified example, the processor 401 can also operate as the target availability setting unit 45 by executing, for example, a management program 4061 stored in the storage 406.

[0091] Next, the operation of the management device 4 according to the modified example will be described. Fig. 9 is a flowchart showing the operation of the management device 4 according to the modified example. The operation shown in Fig. 9 is performed at regular intervals, such as every morning of each day or every morning of one week.

[0092] The operations in steps S1 to S9 are the same as those in Fig. 4. Therefore, a description thereof will be omitted. In other words, when a setting that emphasizes greenness is selected, an operation plan is determined so as to maintain the target value of greenness, i.e., the target value of the quality of the hydrogen produced, as much as possible.

[0093] In step S110, when it is determined in step S4 that an operation plan emphasizing availability is to be determined, the target availability setting unit 45 predicts the current purchase prices of electricity for each of the private renewable energy supply facility 32 and the grid power supply facility 33 based on the actual price data 415. For example, the target availability setting unit 45 predicts the purchase price of electricity based on the past purchase prices of each of the private renewable energy supply facility 32 and the grid power supply facility 33. The prediction of the purchase price of electricity may be performed based on a prediction model that predicts the purchase price of electricity based on inputs such as weather conditions and fuel costs. Furthermore, the target availability setting unit 45 may set the amount of power generated by the private renewable energy supply facility 32 predicted in step S1 as the available supply amount. The electricity generated by the private renewable energy supply facility 32 can be used not only by the facility itself but also distributed to other consumers. Here, it is necessary that the private renewable energy supply facility 32 is not set to supply more electricity than the actual amount of power generated. Therefore, the target availability setting unit 45 predicts the amount of power that can be distributed to its own water electrolysis facility 2 and other consumers so that there is no overlap in the power supplied from the private renewable energy supply facility 32 to each consumer.

[0094] In step S111, the target availability setting unit 45 may certify how much power has been supplied to each consumer at each time from the private renewable energy supply facility 32 so as to prevent overlap with the supply to other consumers. The certification may be performed, for example, by issuing a digital certificate. Furthermore, a sales ledger may be created based on the certificate and the actual power generation record.

[0095] In step S112, the target availability setting unit 45 resets the availability target value based on the available supply amount, the purchase price of electricity, and the sales price of the hydrogen produced. For example, if electricity generated by the private renewable energy supply facility 32 is purchased within the available supply amount, the target availability value is reset so that the difference between the purchase price of electricity and the sales price of hydrogen when hydrogen is produced at the reset target availability value is equal to or greater than a certain amount. As long as the difference is equal to or greater than the certain amount, the target availability value input by the user takes precedence. Here, the sales price of hydrogen when hydrogen is produced at the reset target availability value may be calculated based on the greenness index and hydrogen sales price data as the price performance data 415, which are recalculated from the operation plan for the reset target availability value. Alternatively, the sales price of hydrogen when hydrogen is produced at the reset target availability value may be calculated based on a prediction model that predicts the sales price of hydrogen based on inputs such as the target availability value and the operation plan.

[0096] In step S113, the operation plan determination unit 44 determines whether or not to use the storage battery 23 when operating the water electrolysis cell. The determination of whether or not to use the storage battery 23 when operating the water electrolysis cell is made based on, for example, a user input. If it is determined in step S113 that the storage battery 23 will not be used when operating the water electrolysis cell, the process proceeds to step S114. If it is determined in step S113 that the storage battery 23 will be used when operating the water electrolysis cell, the process proceeds to step S115.

[0097] In step S114, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so as to achieve the reset target value of the availability rate without using the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters including the reset target value of the availability rate into an operation simulator.

[0098] In step S115, the operation plan determination unit 44 determines an operation plan for the water electrolysis equipment 2 so as to achieve the reset target value for the availability while utilizing the power stored in the storage battery 23. Specifically, the operation plan determination unit 44 determines an optimal operation plan by inputting various parameters, including the reset target value for the availability and the remaining capacity of the storage battery 23, into an operation simulator.

[0099] In step S116, the operation plan determination unit 44 performs control based on the determined operation plan. Specifically, the operation plan determination unit 44 notifies the water electrolysis equipment 2 of the determined operation plan. The water electrolysis equipment 2 performs operation based on the notified operation plan.

[0100] In step S117, the greenness index calculation unit 43 recalculates the greenness index.

[0101] In step S118, the greenness index calculation unit 43 outputs the greenness index of the hydrogen produced through operation of the water electrolysis equipment 2. The greenness index is likely to be output to the display device 403 of the management device 4, the hydrogen sales management device 5, or the like. When the greenness index is output to the hydrogen sales management device 5, the hydrogen sales management device 5 can determine the selling price of the hydrogen in accordance with the greenness index.

[0102] In the modified example described above, the target value of the availability rate is reset based on the predicted purchase price of electricity and the sales price of hydrogen, thereby making it possible to balance the prices of purchased electricity and sold hydrogen.

[0103] 9, the target value of the availability rate is reset taking into consideration both the purchase price of electricity and the selling price of hydrogen, but the target value of the availability rate may also be reset taking into consideration only one of the purchase price of electricity or the selling price of hydrogen. For example, the target value of the availability rate may be reset so that the purchase price of electricity does not increase by more than a certain amount, or the target value of the availability rate may be reset so that the selling price of hydrogen does not decrease by more than a certain amount.

[0104] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention.

[0105] 1 Hydrogen production system, 2 Water electrolysis equipment, 3 Power supply equipment, 4 Management device, 5 Hydrogen sales management device, 21 Control device, 22 Water electrolysis equipment, 23 Storage battery, 31, 32 Self-owned renewable energy (renewable energy) supply equipment, 33 Grid power supply equipment, 41 Database (DB), 42 Power generation amount prediction unit, 43 Green degree calculation unit, 44 Operation plan determination unit, 45 Target operation rate setting unit, 401 Processor, 402 Input device, 403 Display device, 404 Communication device, 405 Memory, 406 Storage, 407 Bus, 411 Renewable energy power generation amount record data, 412 Weather record data, 413 Demand record data, 414 Operation record data, 415 Price record data, 421 Self-owned power generation amount prediction unit, 422 Grid power generation amount prediction unit, 441 Operation simulator, 2201 Electrolytic cell, 2202 Anolyte circulation tank, 2203 Catholyte circulation tank, 2204 Electrolyte circulation pump, 2205 Electrolyte cooler, 2206 Mist separator, 2207 Washing tower, 2208 Candle filter, 2209 Buffer tank, 2210 Compressor, 2211 Hydrogen gas purification device, 2212 Mist separator, 2213 Washing tower, 2214 Candle filter, 2215 Oxygen gas seal pot, 4061 Management program, 4062 Database (DB), 4063 Self-generated power generation amount prediction model, 4064 System power generation amount prediction model, 4065 Operation simulator.

Claims

1. A management device including a green index calculation unit that calculates the ratio of the amount of renewable energy electricity to the amount of electricity input only to a water electrolysis cell that produces hydrogen by water electrolysis using input electricity, as a green index that represents the degree of contribution of the hydrogen to the environment, and outputs the green index.

2. The management device of claim 1, wherein the electricity from the renewable energy is supplied to the water electrolysis cell from a renewable energy supply facility, and the amount of electricity from the renewable energy input to the water electrolysis cell is calculated based on measurement data of the amount of power generated by the renewable energy supply facility.

3. The management device according to claim 1, wherein electricity from the renewable energy is input to the water electrolysis cell from a renewable energy supply facility via a grid transmission line, and the amount of electricity from the renewable energy input to the water electrolysis cell is calculated based on purchasing data of the renewable energy.

4. The management device of claim 1, wherein the water electrolysis cell is configured to receive power from a storage battery, and the greenness calculation unit calculates the greenness level by further including a ratio of the amount of renewable energy power to the amount of power input from the storage battery to the water electrolysis cell.

5. The management device according to claim 1, further comprising an operation plan determination unit that determines an operation plan for a water electrolysis facility including the water electrolysis cell based on the greenness level.

6. The management device according to claim 5, wherein the operation plan determination unit determines the operation plan for the water electrolysis facility further based on the availability rate of the water electrolysis facility.

7. The management device according to claim 6, further comprising an operation rate setting unit that resets the operation rate of the water electrolysis equipment based on a selling price of the produced hydrogen, which is determined based on the green degree, and on a supplyable amount and purchase price of electricity used for producing the hydrogen.

8. The management device according to claim 7, wherein the operation rate setting unit issues a certificate certifying the amount of renewable energy power supplied to each consumer at each time based on the available supply amount.

9. The management device according to claim 5, wherein the water electrolysis cell is configured to receive power from a storage battery, and the operation plan determination unit determines the operation plan by further including power to be input from the storage battery only to the water electrolysis cell.

10. A management method comprising: calculating a ratio of the amount of electricity from renewable energy to the amount of electricity input only to a water electrolysis cell that produces hydrogen by water electrolysis using the input electricity, as a green index that represents the degree of contribution of the hydrogen to the environment; and outputting the green index.

11. A management program for causing a computer to execute the following steps: calculating a ratio of the amount of electricity from renewable energy to the amount of electricity input only to a water electrolysis cell that produces hydrogen by water electrolysis using input electricity, as a green index that indicates the degree of contribution of the hydrogen to the environment; and outputting the green index.

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