Energy Management System

Abstract

To provide an energy management system that can reduce energy cost.SOLUTION: An energy management system 1 controls preheating of a hydrogen generator 2 that converts system power to hydrogen. The energy management system 1 has a collection part 11 that collects external information regarding at least either one of the power or hydrogen, a recording part 12 that records device information regarding the hydrogen generator 2, and a control part 13 that controls preheating of the hydrogen generator 2 based on the external information and the device information.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an energy management system. [Background technology]

[0002] Patent Document 1 discloses a cogeneration type regulating power supply equipped with multiple fuel cells. In this power supply, one fuel cell is operated continuously so that the current density is constant, while the other fuel cell is operated while varying the output according to the power demand. The heat generated between the multiple fuel cells is transferred between them to reduce energy costs. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-11903 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the system disclosed in Patent Document 1, multiple fuel cells are operated all the time. Therefore, the multiple fuel cells need to be kept at an operating temperature all the time, which requires a lot of thermal energy. Therefore, the energy cost tends to be high.

[0005] The present invention has been made in view of the above problems, and aims to provide an energy management system that can reduce energy costs. [Means for solving the problem]

[0006] One aspect of the present invention is an energy management system (1) that controls preheating of a hydrogen generation device (2) that generates hydrogen using grid power, comprising: A collection unit (11) that collects external information including information regarding at least one of electricity and hydrogen; A recording unit (12) that records device information related to the hydrogen generation device; a control unit (13) that controls preheating of the hydrogen generation device based on the external information and the device information. death, The external information includes information regarding hydrogen costs and electricity costs; The recording unit records, as the device information, the efficiency of conversion from electricity to hydrogen by the hydrogen generation device, the collection unit collects, as the external information, the electricity purchase price and the hydrogen purchase price, and the control unit determines whether or not to preheat the hydrogen generation device based on the conversion efficiency, the electricity purchase price, and the hydrogen purchase price. , in energy management systems. Effect of the Invention

[0007] The energy management system has a control unit that controls preheating of the hydrogen generation device based on the external information and the device information. Therefore, it is possible to perform preheating of the hydrogen generation device at the necessary timing. In other words, it is possible to stop preheating of the hydrogen generation device at the time when preheating is not necessary, thereby saving energy. Therefore, it is possible to reduce energy costs.

[0008] As described above, according to the above aspect, it is possible to provide an energy management system that can reduce energy costs. In addition, the symbols in parentheses described in the claims and the means for solving the problems indicate a correspondence with the specific means described in the embodiments described below, and do not limit the technical scope of the present invention. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram of an energy management system according to a first embodiment. [Diagram 2] FIG. 4 is a flow diagram showing an example of a control flow in the first embodiment. [Diagram 3] FIG. 11 is an explanatory diagram of an energy management system in a second embodiment. [Figure 4] FIG. 11 is an explanatory diagram of an energy management system in a third embodiment. [Diagram 5]FIG. 11 is an explanatory diagram of an energy management system in a fourth embodiment. [Figure 6] 13A is a diagram showing an example of a time transition of a reception probability, and FIG. 13B is a diagram showing an example of a time transition of a control temperature of an SOEC in embodiment 4. [Figure 7] 13A is a diagram showing another example of the time transition of the reception probability, and FIG. 13B is a diagram showing another example of the time transition of the control temperature of the SOEC in the fourth embodiment. [Figure 8] 13A is a diagram showing a state in which the prediction of the time transition of the reception probability is changed, and FIG. 13B is a diagram showing a state in which the time transition of the control temperature of the SOEC is changed, in the fourth embodiment. [Figure 9] FIG. 13 is an explanatory diagram of an energy management system in a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Embodiment 1) An embodiment of an energy management system will be described with reference to FIGS. The energy management system 1 of this embodiment is a system that controls preheating of a hydrogen generation device 2 that generates hydrogen using grid power.

[0011] As shown in FIG. 1, the energy management system 1 includes a collection unit 11, a recording unit 12, and a control unit 13. The collecting unit 11 collects external information including information related to at least one of electric power and hydrogen. The recording unit 12 records device information related to the hydrogen generator 2. The control unit 13 controls preheating of the hydrogen generator 2 based on the external information and the device information.

[0012] In this embodiment, the hydrogen generator 2 is composed of, for example, a solid oxide electrolysis cell (i.e., SOEC). Hereinafter, the hydrogen generator 2 is also referred to as "SOEC2." Water and an oxidant gas (e.g., air) are supplied to the SOEC2. In this state, by supplying power to the SOEC2, the water is electrolyzed and hydrogen is generated. The power supplied to the SOEC2 is grid power. In other words, power purchased from the power grid is used for electrolysis in the SOEC2.

[0013] In the process of hydrogen generation by the SOEC2, the process of evaporating liquid water and the process of electrolysis reaction by the electrolyte, which is an endothermic reaction, are performed. Therefore, it is necessary to supply heat to the SOEC2 during electrolysis. In other words, it is necessary to preheat the SOEC2 to a predetermined temperature before operating the SOEC2.

[0014] A preheater 3 that preheats the SOEC 2 is connected to the SOEC 2. The preheater 3 is configured to be able to preheat the SOEC 2, for example, by supplying high-temperature air to the SOEC 2.

[0015] The hydrogen generated in the SOEC 2 is supplied to consumers 4. Here, consumers 4 refer to, for example, factories, homes, and other facilities and equipment that consume hydrogen. Consumers 4 can also use the supplied hydrogen by converting it into electricity using their own conversion device (for example, a fuel cell, etc.).

[0016] Also, as shown in FIG. 1, in this embodiment, hydrogen can be supplied to consumer 4 via a different route, not via SOEC 2. For example, consumer 4 can directly purchase hydrogen and receive the supply. Thus, the supply routes of hydrogen to consumer 4 include a route in which grid power is converted into hydrogen by SOEC 2 and supplied to consumer 4, and a route in which purchased hydrogen is directly supplied to consumer 4. Note that "converting electricity into hydrogen" means generating hydrogen from water using electricity. The same applies hereinafter.

[0017] The energy management system 1 of this embodiment manages the preheating of the SOEC 2 in accordance with the management of the use of the above two paths. As described above, the energy management system 1 has the collection unit 11, the recording unit 12, and the control unit 13.

[0018] The collection unit 11 collects external information including information on at least one of electricity and hydrogen. In this embodiment, the external information includes information on hydrogen cost and electricity cost. The external information may also include information on the operating status of the hydrogen generation device 2, the device temperature, and further information on the season, time, day of the week, weather forecast, and the like. The collection unit 11 can be configured, for example, by a terminal such as a personal computer, various sensors, and the like.

[0019] The recording unit 12 records device information related to the SOEC 2. The device information includes, for example, the conversion efficiency of converting electric power into hydrogen, the device temperature required for electrolysis operation (hereinafter also referred to as "operating temperature" as appropriate), information on preheating time, etc. As the information on the preheating time, for example, a map or the like that can derive the preheating time required to reach the operating temperature based on the current device temperature, outside air temperature, and further the preheating capacity of the preheater 3 collected by the collecting unit 11, is assumed.

[0020] The device information may also include past operation records of the SOEC2. For example, it is assumed that a determination as to whether or not to preheat the SOEC2 is made based on the relationship between various factors such as the season, time, day of the week, and weather forecast and past operation records of the SOEC2. In such a case, the device information also includes the past operation records of the SOEC2. The recording unit 12 can be configured, for example, by a semiconductor memory.

[0021] Based on the external information and the device information, the control unit 13 controls the preheating of the SOEC 2. That is, based on the hydrogen cost and the electricity cost obtained as the external information and the conversion efficiency of the hydrogen generation device 2, the control unit 13 judges whether it is more cost-effective to directly purchase hydrogen or to convert grid power into hydrogen in the SOEC 2.

[0022] Specifically, the recording unit 12 records, as the device information, the efficiency of conversion from electricity to hydrogen by the SOEC 2. The collecting unit 11 collects, as the external information, the electricity purchasing price and the hydrogen purchasing price. The control unit 13 determines whether or not to preheat the SOEC 2 by the preheater 3, based on the conversion efficiency, the electricity purchasing price, and the hydrogen purchasing price.

[0023] The control unit 13 is also configured to transmit a preheating signal to the preheater 3 to allow the preheater 3 to preheat the SOEC 2. That is, the control unit 13 includes, as a means for transmitting the preheating signal, a communication unit that performs, for example, wireless communication or wired communication. The control unit 13 is, for example, a processor that executes a control program stored in the energy management system 1, and can be configured by a microcomputer or a dedicated circuit.

[0024] The energy management system 1 of this embodiment can control the preheating of the SOEC 2, for example, as shown in the flow chart of FIG. Here, "electricity purchase price C1" is the purchase price per kWh of electricity from the power grid. "Hydrogen purchase price C2" is the purchase price per kWh of electricity from the power grid. 3 The "conversion efficiency η" of SOEC2 is the energy conversion efficiency when converting electricity into hydrogen. In other words, the conversion efficiency η is the total heat of hydrogen obtained relative to the total amount of electricity consumed during electrolysis in SOEC2.

[0025] Here, "the total amount of power consumed during electrolysis in SOEC2" includes, in addition to the amount of power directly supplied to the electrolyte in SOEC2, the amount of power supplied to preheat SOEC2 via preheater 3, the amount of power supplied to generate steam used in SOEC2, etc. In other words, "the total amount of power consumed during electrolysis in SOEC2" means the total amount of power required to obtain a predetermined amount of hydrogen. In addition, hydrogen 1Nm 3 The "hydrogen calorific value Q" is defined as the calorific value per unit (unit: kWh).

[0026] The collecting unit 11 collects information on the electricity purchasing price C1 and the hydrogen purchasing price C2 (see step S1 in FIG. 2). In the control unit 13, the product of the electricity purchase price C1 and the hydrogen heat quantity Q is divided by the conversion efficiency η (i.e., C1 × Q ÷ η) to obtain a value of 1 Nm 3 The cost C10 required to obtain 1 Nm of hydrogen is calculated as C10 (see step S2). 3 This cost C10 is compared with the hydrogen purchasing price C2 (see step S3).

[0027] If C2>C10, it will be more cost-effective to purchase grid power, convert it to hydrogen, and supply it to the consumer 4. Therefore, in this case, the purchased power is converted to hydrogen by the SOEC 2 and supplied to the consumer 4. To do so, the control unit 13 of the energy management system 1 sends a preheating signal to the preheater 3 to operate the SOEC 2 (see step S4).

[0028] On the one hand, if C2 < C10, it is more cost-effective to purchase hydrogen and directly supply it to the consumer 4. Therefore, in this case, instead of using SOEC2, the purchased hydrogen will be supplied to the consumer 4. At this time, since SOEC2 is not used, preheating of SOEC2 is also unnecessary. Therefore, the control unit 13 stops transmitting the preheating signal to the preheater 3 (see step S5). In other words, a preheating stop signal is sent to the preheater 3. Thereby, the preheating of SOEC2 by the preheater 3 is stopped, and unnecessary preheating energy of SOEC2 is saved.

[0029] In the case of C2 = C10, it is possible either to stop preheating or to perform preheating. For example, if preheating has been carried out until that point, preheating can be continued, and if preheating has been stopped until that point, the preheating stop can be continued.

[0030] Also, the timing such as the start time and stop time of preheating is determined based on various factors. The energy management system 1 performs preheating control so that SOEC2 is at or above the operating temperature during the time period when SOEC2 is operated, and controls so that SOEC2 is below the operating temperature as much as possible during the time period when SOEC2 is not operated. The start time of operation does not coincide with the start time of preheating, nor does the stop time of operation coincide with the stop time of preheating.

[0031] Next, the operation and effect of this embodiment will be described. The energy management system 1 described above has a control unit 13 that controls the preheating of SOEC2 based on external information and device information. Therefore, it is possible to perform the preheating of SOEC2 at the necessary timing. Conversely, it is possible to stop preheating, etc. when preheating of SOEC2 is unnecessary, and energy can be saved. Therefore, reduction of energy cost can be achieved.

[0032] That is, even in a situation where the operation of the SOEC2 is not required, if the preheating of the SOEC2 is continued, the energy cost will increase accordingly. Therefore, the energy management system 1 determines whether or not the preheating of the SOEC2 is required based on external information and device information, and is capable of stopping the preheating when the preheating is not required. This makes it possible to save unnecessary energy and reduce the energy cost.

[0033] The external information also includes information on hydrogen costs and electricity costs, which makes it easier to decide whether to purchase hydrogen directly without operating the SOEC2, or to convert electricity into hydrogen using the SOEC2. Accordingly, it is easier to decide whether to preheat the SOEC2.

[0034] Furthermore, the control unit 13 determines whether or not to preheat the SOEC 2 by the preheater 3 based on the conversion efficiency, the electricity purchase price, and the hydrogen purchase price. This makes it easy to easily and accurately determine whether or not to preheat the SOEC 2.

[0035] As described above, according to the present embodiment, it is possible to provide an energy management system that can reduce energy costs.

[0036] (Embodiment 2) This embodiment is a form of energy management system 1 in which a hydrogen tank 5 and a fuel cell 6 are provided between an SOEC 2 and a consumer 4, as shown in FIG. The hydrogen tank 5 stores the hydrogen generated by the SOEC 2. The fuel cell 6 converts the hydrogen stored in the hydrogen tank 5 into electricity and supplies it to the consumer 4.

[0037] For example, a solid oxide fuel cell (i.e., SOFC) can be used as the fuel cell 6. Hereinafter, the fuel cell 6 is also referred to as "SOFC 6" as appropriate. The SOFC 6 generates electricity by reacting supplied hydrogen and oxygen in a solid electrolyte.

[0038] The SOEC 2 and SOFC 6 may also be comprised of reversible solid oxide fuel cells (ie, rSOFCs), which are capable of, for example, converting hydrogen to electricity and vice versa.

[0039] In this embodiment, there is a route for directly supplying grid power to the consumer 4. There is also a route for temporarily converting grid power into hydrogen and storing it, and then converting the stored hydrogen back into electricity and supplying it to the consumer 4.

[0040] The latter path is provided with an SOEC 2, a hydrogen tank 5, and an SOFC 6. That is, in the latter path, grid power is converted into hydrogen by the SOEC 2, and the hydrogen is stored in the hydrogen tank 5. The hydrogen stored in the hydrogen tank 5 is converted into electricity by the SOFC 6, and the electricity is supplied to the consumer 4. It is also possible to purchase hydrogen and store it in the hydrogen tank 5.

[0041] The control unit 13 has a receiving unit 131 that receives an operation command from the outside to operate the SOEC 2. The control unit 13 controls preheating of the SOEC 2 based on the operation command received by the receiving unit 131. The operation command can be, for example, a part of a DR command (short for demand response command).

[0042] For example, when the power demand in the consumer 4 is low and the power supply from the grid is high, the DR command is sent as an electrical signal from outside (for example, the power company or the consumer 4) to the control unit 13 in the energy management system 1.

[0043] In addition, when the power demand at the consumer 4 exceeds the power supply from the grid power, an external command may be issued to convert the hydrogen in the hydrogen tank 5 into electricity using the SOFC 6 and supply the electricity to the consumer 4.

[0044] In this embodiment, when there is a DR command (i.e., an operation command) commanding operation of the SOEC 2, the control unit 13 sends a preheat signal to the preheater 3. This causes the preheater 3 to preheat the SOEC 2. Note that the operation command can be a command to operate the SOEC 2 in the future, for example, several hours, several minutes, or several seconds. Then, the control unit 13 sends a preheat signal to preheat the SOEC 2 in time for the operation of the SOEC 2.

[0045] As described above, hydrogen is stored in the hydrogen tank 5 in anticipation of the need to supply electricity to the consumer 4 via the SOFC 6. When storing this hydrogen, hydrogen may be purchased directly or grid power may be converted into hydrogen and stored. Here, the control unit 13 determines which route to use to store hydrogen in the hydrogen tank 5 in the same manner as in the first embodiment, and controls the SOEC 2 and preheater 3.

[0046] The rest is the same as in embodiment 1. Note that, among the symbols used in embodiment 2 and onwards, the same symbols used in the previous embodiments represent the same components, etc. as in the previous embodiments, unless otherwise specified.

[0047] In this embodiment, the preheating of the SOEC 2 by the preheater 3 is controlled based on an operation command in the DR command. This makes it possible to reduce energy costs even when the SOEC 2 is operated based on the operation command. In addition, the same effects as those of the first embodiment are achieved.

[0048] (Embodiment 3) As shown in FIG. 4, this embodiment is a configuration in which a power storage device 7 for storing grid power is provided. As the power storage device 7, for example, a storage battery such as a lithium ion battery can be used.

[0049] In this embodiment, for example, when the power demand at the consumer 4 falls below the power supply of the grid power, the control unit 13 of the energy management system 1 can control the power storage device 7 to charge the grid power based on the DR command. That is, at this time, for example, as shown in FIG. 4, the control unit 13 sends a signal to the power storage device 7 to command power storage. Also, when the surplus of the grid power exceeds the charging power to the power storage device 7, that amount can be supplied to the SOEC 2. Then, when the control unit 13 receives such a command, it operates the SOEC 2. In such a case, the control unit 13 sends a preheating signal to the preheater 3.

[0050] The power stored in the power storage device 7 is supplied to the consumer 4 when the power demand at the consumer 4 exceeds the power supply from the grid power. Alternatively, when the current power price exceeds the power price at the time the power was stored in the power storage device 7, the stored power is preferentially supplied to the consumer (not shown). The rest is the same as in the first embodiment.

[0051] In this embodiment as well, it is possible to reduce energy costs by suppressing unnecessary preheating of the SOEC 2. In addition, the same effects as those of the first embodiment are obtained.

[0052] (Embodiment 4) In this embodiment, the control unit 13 further includes a probability prediction unit 132, as shown in FIGS. The probability prediction unit 132 predicts a reception probability P at which the receiving unit 131 receives the operation command. The control unit 13 is configured to adjust the degree of pre-heating of the SOEC 2 according to the reception probability P predicted by the probability prediction unit 132.

[0053] The probability prediction unit 132 is a part of the control unit 13, and can be configured with a microcomputer or a dedicated circuit, etc. The probability prediction unit 132 predicts the reception probability P based on information related to the season, time, day of the week, weather forecast, etc. The information related to the season, time, day of the week, weather forecast, etc. is collected by the collection unit 11 as described above.

[0054] For example, when a power utility company has a solar power generation device, the amount of power that can be supplied by the solar power generation device increases around noon on a clear day. Under such circumstances, the amount of power supply increases relative to the power demand, and the probability that a DR command (also an operation command here) reaches the receiver 131 (i.e., the reception probability P) increases. The transition prediction of the reception probability P shown in FIG. 6(a) can be considered to assume, for example, such a situation.

[0055] According to this reception probability P, the control unit 13 controls the temperature of the SOEC 2 by the preheater 3. That is, in the example shown in FIG. 6(a), the reception probability P increases from time t1 to t2, and at time t2, the reception probability P is approximately 100%. When the probability prediction unit 132 predicts the fluctuation of the reception probability P in this way, the SOEC 2 is preheated so that the temperature of the SOEC 2 reaches the operating temperature T0 (i.e., the temperature required for electrolysis) at time t2, as shown in FIG. 6(b). That is, the control unit 13 sends such a preheat signal to the preheater 3.

[0056] As another example, as shown in Fig. 7(a), a case where the reception probability P increases stepwise is also assumed. In the example of the figure, it is predicted that the reception probability P increases from about 0% to about 20% at time t3, and then increases sharply just before time t4, reaching about 100% at time t4.

[0057] When the probability prediction unit 132 makes such a probability prediction, as shown in Fig. 7(b), pre-heating control is performed to first raise the temperature of the SOEC2 so that the temperature approaches the operating temperature T0 toward time t3. Then, at time t4, the raising of the temperature of the SOEC2 is resumed so that the SOEC2 can reach the operating temperature T0. In this way, there may be predictions in which a time period in which the reception probability P is not high but exists to a certain extent exists for a certain length of time. In such a case, control may be considered to maintain the temperature of the SOEC2 at a temperature lower than the operating temperature T0 but higher than the outside air temperature.

[0058] In this way, when the probability prediction changes over time, for example, as shown in Fig. 8(a), it becomes easier to take measures such as changing the pre-heating plan. That is, as shown in the figure, consider a case where the transition of the reception probability P predicted at time t0 (see Fig. 7(a)) changes to the transition of the reception probability P shown in Fig. 8(a) in the prediction at time t5. In this case, since it is not necessary to increase the temperature of the SOEC2, the pre-heating plan can be re-planned at time t5 as shown in Fig. 8(b).

[0059] This makes it possible to avoid pre-heating of SOEC2, which does not require pre-heating. In other words, since the temperature of SOEC2 is relatively low even in the initial plan at time t5, even if the reception probability P drops significantly, by avoiding subsequent pre-heating, it is possible to reduce unnecessary pre-heating energy. In FIG. 8(a), the dashed line LP indicates the transition of the reception probability P predicted at time t0 (see FIG. 7(a)). In FIG. 8(b), the dashed line LT indicates the transition of the temperature of SOEC2 planned at time t0 (see FIG. 7(b)).

[0060] The rest is the same as in the second embodiment, and has the same effects.

[0061] (Embodiment 5) As shown in FIG. 9, this embodiment is an energy management system 1 configured to be capable of individually controlling the preheating of a plurality of hydrogen generators 2.

[0062] In this embodiment, two SOECs 2 are provided as the hydrogen generation device 2. The two SOECs 2 are configured to convert grid power into hydrogen, and to send the generated hydrogen to the hydrogen tank 5.

[0063] Then, the control unit 13 of the energy management system 1 controls the preheating of each of the two SOECs 2 by the preheater 3.

[0064] For example, two SOECs 2 are operated based on a DR command. At this time, for example, if the grid power significantly exceeds the power demand of consumers 4, it is desirable to convert a large amount of power into hydrogen and store it in hydrogen tank 5. In such a case, an operation command to operate both SOECs 2 is sent to control unit 13 via receiving unit 131. Based on this, control unit 13 transmits a pre-heat signal to pre-heat both SOECs 2.

[0065] On the other hand, for example, when the grid power exceeds the power demand of the consumer 4 but the difference is relatively small, it may be possible to cover the power conversion to hydrogen with only one SOEC 2. In such a case, an operation command to operate only one SOEC 2 is sent to the control unit 13 via the receiving unit 131. Based on this, the control unit 13 transmits a preheating signal to preheat one of the SOECs 2. At this time, the other SOEC 2 is not preheated.

[0066] Also, for example, when it is necessary to supply hydrogen to the hydrogen tank 5 and it is determined in step S3 of FIG. 2 in the first embodiment that C2>C10, the SOEC2 is preheated.

[0067] At this time, if the required rate of supplying hydrogen to the hydrogen tank 5 is high, both SOECs 2 are operated. To this end, the control unit 13 transmits a preheat signal to preheat both SOECs 2.

[0068] On the other hand, when the required rate at which hydrogen is supplied to the hydrogen tank 5 is not fast, only one SOEC 2 is operated. To this end, the control unit 13 transmits a preheat signal to preheat one of the SOECs 2. At this time, the other SOEC 2 is not preheated.

[0069] In this way, only the SOEC2 that is required to operate is preheated, which saves unnecessary preheating energy. The rest is the same as in the second embodiment.

[0070] In this embodiment, it is possible to effectively reduce the energy cost when using a plurality of SOECs 2. In addition, the present embodiment has the same effects as those of the second embodiment. In the above description, the case where two hydrogen generators (that is, SOEC2) are used has been described. However, similar control is possible and similar effects are achieved when three or more hydrogen generators are used.

[0071] The present invention is not limited to the above-described embodiments, and can be applied to various embodiments without departing from the gist of the present invention. [Explanation of symbols]

[0072] 1. Energy Management System 11 Collection Department 12 Recording section 13 Control section 2. Hydrogen generation equipment (SOEC) 4 Consumer

Claims

1. An energy management system (1) for controlling preheating of a hydrogen generation device (2) for generating hydrogen using grid power, comprising: A collection unit (11) that collects external information including information regarding at least one of electricity and hydrogen; A recording unit (12) for recording device information related to the hydrogen generation device; a control unit (13) that controls preheating of the hydrogen generation device based on the external information and the device information, The external information includes information regarding hydrogen costs and electricity costs; An energy management system in which the recording unit records the efficiency of conversion from electricity to hydrogen by the hydrogen generation device as the device information, the collection unit collects the electricity purchase price and the hydrogen purchase price as the external information, and the control unit determines whether or not to preheat the hydrogen generation device based on the conversion efficiency, the electricity purchase price, and the hydrogen purchase price.

2. 2. The energy management system of claim 1, wherein the control unit has a receiving unit (131) that receives an operation command to operate the hydrogen generation device from the outside, and controls preheating of the hydrogen generation device based on the operation command received by the receiving unit.

3. 3. The energy management system of claim 2, wherein the control unit further has a probability prediction unit (132) that predicts a reception probability that the receiving unit will receive the operation command, and the control unit is configured to adjust a degree of pre-heating of the hydrogen generation apparatus according to the reception probability predicted by the probability prediction unit.

4. The energy management system according to any one of claims 1 to 3, wherein the energy management system is configured to be capable of individually controlling preheating of each of the plurality of hydrogen generators.

Images