Supply system

Abstract

To suppress a discharge of a hydrogen boil-off gas to an atmosphere.SOLUTION: A supply system includes: a fuel battery that generates an electric power using a hydrogen boil-off gas vaporized in a container that stores a liquid hydrogen; a battery 2 that stores the electric power generated by the fuel battery; a generation amount prediction part 822 that predicts the generation amount of the hydrogen boil-off gas generated during a stop period in which the fuel battery that generates a power using the liquid hydrogen in the container stops for a predetermined time or longer; a power generation amount prediction part 823 that predicts the generation amount of the electric power that can be generated by the fuel battery using the generation amount of the hydrogen boil-off gas; a capacity control part 824 that reduces a remaining capacity of the battery 2 before the stop period is reached when the predicted amount of the power generated is larger than the amount of the power that can be charged into the battery; and a supply control part 825 that causes the fuel battery to generate the power with the hydrogen boil-off gas by supplying the hydrogen boil-off gas generated during the stop period to the fuel battery.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a supply system for supplying power to a battery. [Background technology]

[0002] Vehicles equipped with fuel cells that generate electricity through an electrochemical reaction between hydrogen and oxygen are known. Patent Document 1 discloses a technology in which liquid hydrogen is stored in a container mounted on the vehicle and hydrogen is supplied from the container to the fuel cell. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-327227 Summary of the Invention [Problem to be solved by the invention]

[0004] In a container that stores liquid hydrogen, hydrogen boil-off gas is generated when the liquid hydrogen vaporizes due to natural heat input from outside the container. If a fuel cell does not generate electricity for an extended period of time, the hydrogen in the container is not consumed even though hydrogen boil-off gas is generated, and the hydrogen boil-off gas increases in the container. This increase in hydrogen boil-off gas in the container increases the pressure inside the container. For this reason, it was necessary to discharge the hydrogen boil-off gas generated in the container to the outside before the pressure exceeded the container's withstand pressure.

[0005] The present invention has been made in consideration of these points, and aims to suppress the emission of hydrogen boil-off gas into the atmosphere. [Means for solving the problem]

[0006] In one aspect of the present invention, a supply system is provided that includes: a fuel cell that generates electricity using hydrogen boil-off gas vaporized in a container that stores liquid hydrogen; a battery that stores the electricity generated by the fuel cell; a first prediction unit that predicts the amount of hydrogen boil-off gas that will be generated during an outage period in which a power unit that generates power using the liquid hydrogen in the container is stopped for a predetermined period of time or longer; a second prediction unit that predicts the amount of electricity that can be generated by the fuel cell using the generated amount of hydrogen boil-off gas; a first control unit that reduces the remaining capacity of the battery before the outage period begins if the predicted amount of electricity generated is greater than the amount of electricity that can be charged to the battery; and a second control unit that supplies the hydrogen boil-off gas generated during the outage period to the fuel cell, causing the fuel cell to generate electricity using the hydrogen boil-off gas.

[0007] The first prediction unit may predict, as the generation amount, a product of a unit generation amount of the hydrogen boil-off gas per unit time and a length of the stop period.

[0008] The first prediction unit may predict the unit generation amount based on an air temperature during the stop period in a predetermined space where the container is located.

[0009] The first prediction unit may increase the amount of generation at times during the shutdown period when sunlight hits the device that carries the container, compared to the amount of generation at times when sunlight does not hit the device.

[0010] The first prediction unit may, based on a weather forecast predicting the weather during the stopped period, increase the amount of generation during times when the weather is sunny compared to the amount of generation during times when the weather is not sunny.

[0011] The first control unit may reduce the remaining capacity until the amount of power that can be charged into the battery, which is determined by subtracting the remaining capacity from the maximum capacity of the battery, is equal to or greater than the predicted amount of power generation.

[0012] The second prediction unit may predict the amount of power generation when the pressure in the container becomes greater than a predetermined pressure for determining whether or not to discharge the hydrogen boil-off gas in the container due to the generation of the amount of hydrogen boil-off gas during the shutdown period. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress the emission of hydrogen boil-off gas into the atmosphere. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a diagram illustrating a configuration of a supply system. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a supply control device. [Figure 3] 10 is a data table showing an example of schedule information. [Figure 4] This is an example of a data table that associates temperature with unit generation amount. [Figure 5] 10 is an example of a data table predicting unit generation amounts for each time period. [Figure 6] 4 is a flowchart showing an example of a process for suppressing emission of hydrogen boil-off gas into the atmosphere. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Configuration of supply system S] 1 is a diagram illustrating the configuration of a supply system S. The supply system S is mounted on a vehicle. The supply system S is a system for supplying power from a fuel cell 1 to a motor 4. The supply system S includes the fuel cell 1, a battery 2, an inverter 3, a motor 4, a driven device 5, a container 6, a supply control device 8, a supply valve 71, and a purge valve 72.

[0016] The fuel cell 1 is a power unit that generates power using liquid hydrogen. The fuel cell 1 generates electrical energy as power. The fuel cell 1 is an electrochemical cell that generates power when supplied with hydrogen vaporized from liquid hydrogen and oxygen. Specifically, the fuel cell 1 generates power by converting the energy of an oxidation-reduction reaction between hydrogen and oxygen into electrical energy. The fuel cell 1 generates power using hydrogen and oxygen and outputs direct current. The fuel cell 1 supplies the output current to the battery 2 and inverter 3.

[0017] The battery 2 is a secondary battery that stores and supplies electric power. The battery 2 stores the electric power supplied from the fuel cell 1. The battery 2 also supplies the stored electric power to the inverter 3.

[0018] The inverter 3 is an inverse conversion circuit capable of converting DC current into AC current. The inverter 3 converts the DC current supplied from the fuel cell 1 or the battery 2 into AC current capable of driving the motor 4 and supplies it to the motor 4.

[0019] The motor 4 operates when power is supplied from the inverter 3. The motor 4 drives a driven device 5 connected to an output shaft of the motor 4. The driven device 5 includes, for example, a transmission 51. In addition to the transmission 51, the driven device 5 may also include a propeller shaft, a differential, a drive shaft, and wheels connected to the transmission 51.

[0020] Container 6 stores liquid hydrogen, which is liquefied hydrogen. The liquid hydrogen is stored in container 6 at a temperature at which hydrogen can remain in a liquid state (for example, below -252.9°C, at which hydrogen liquefies). Container 6 is, for example, cylindrical in shape, but is not limited to this. Heat insulating material is provided inside container 6. The capacity of container 6 is, for example, 30 liters, but is not limited to this.

[0021] The container 6 and the fuel cell 1 are connected by a first supply pipe 61. A vaporizer 62 for vaporizing liquid hydrogen is provided in the first supply pipe 61 between the container 6 and the fuel cell 1. The vaporizer 62 is provided with a pipe through which cooling water for cooling the fuel cell 1 is circulated. The vaporizer 62 vaporizes the liquid hydrogen by utilizing the heat of the cooling water.

[0022] The container 6 is provided with a pressure sensor 63 that detects the pressure inside the container 6. The pressure sensor 63 is, for example, a semiconductor piezo-resistive diffusion pressure sensor. The semiconductor piezo-resistive diffusion pressure sensor is a sensor that detects a change in pressure by detecting a change in electrical resistance that occurs when a strain gauge formed on the surface of a diaphragm is deformed by external pressure, but is not limited to this. The pressure sensor 63 outputs the detected pressure to the purge valve 72 and the supply control device 8.

[0023] A valve 70 is provided in first supply pipe 61 between vaporizer 62 and container 6. Valve 70 is a control valve that switches between allowing and blocking the passage of liquid hydrogen from container 6 to vaporizer 62. When valve 70 is opened, liquid hydrogen in container 6 is supplied to vaporizer 62.

[0024] Although heat insulation is provided inside the container 6, atmospheric heat still flows into the container 6. When atmospheric heat flows into the container 6, the temperature of the liquid hydrogen rises, causing the liquid hydrogen to vaporize and generate hydrogen boil-off gas. In particular, if the fuel cell 1 is stopped for an extended period of time due to a holiday for the company that manages the vehicle equipped with the supply system S, the hydrogen in the container is not consumed even when hydrogen boil-off gas is generated, and the amount of hydrogen boil-off gas in the container increases. As the amount of hydrogen boil-off gas in the container increases, the pressure in the container 6 increases. Therefore, it is necessary to discharge the hydrogen boil-off gas generated in the container 6 to the outside of the container 6 to reduce the pressure in the container 6 before the pressure of the hydrogen boil-off gas in the container 6 exceeds the withstand pressure of the container 6.

[0025] A purge pipe 64 is connected to the container 6 for discharging the hydrogen boil-off gas to the atmosphere. A purge valve 72 is provided in the purge pipe 64. The purge valve 72 automatically opens to discharge the boil-off gas when the pressure inside the container 6 reaches or exceeds a predetermined pressure, and automatically closes when the pressure inside the container 6 drops below the predetermined pressure. The predetermined pressure is a value used to determine whether or not to discharge the hydrogen boil-off gas inside the container 6. The predetermined pressure may be set appropriately depending on the pressure resistance of the container 6. A specific value of the predetermined pressure is, for example, 80% of the pressure resistance of the container 6. The hydrogen boil-off gas discharged from the purge valve 72 is discharged to the atmosphere.

[0026] However, if the hydrogen boil-off gas is discharged into the atmosphere, the fuel cell 1 cannot use the hydrogen boil-off gas for power generation. Therefore, the supply system S supplies the hydrogen boil-off gas generated in the container 6 to the fuel cell 1 without discharging it into the atmosphere. The fuel cell 1 and the container 6 are also connected by a second supply pipe 65. The second supply pipe 65 branches off from the purge pipe 64 and is a pipe for supplying the hydrogen boil-off gas to the fuel cell 1. A supply valve 71 is provided between the container 6 and the fuel cell 1 in the second supply pipe 65. The supply valve 71 is a control valve that switches between allowing or blocking the passage of the hydrogen boil-off gas from the container 6 to the fuel cell 1.

[0027] The supply system S supplies the hydrogen boil-off gas to the fuel cell 1 by opening the supply valve 71 before the pressure of the hydrogen boil-off gas exceeds a predetermined pressure. This enables the supply system S to cause the fuel cell 1 to generate power using the hydrogen boil-off gas. In this way, the supply system S can use the hydrogen boil-off gas generated in the container 6 for power generation by the fuel cell 1 without discharging it into the atmosphere.

[0028] As described above, the supply system S can suppress the emission of hydrogen boil-off gas into the atmosphere by supplying hydrogen boil-off gas to the fuel cell 1 before the pressure in the container 6 reaches a predetermined pressure. However, if the remaining capacity of the battery 2 is large and the battery 2 cannot charge the electricity generated by the fuel cell 1, the supply system S cannot cause the fuel cell 1 to generate electricity using the hydrogen boil-off gas. Therefore, the supply control device 8 of the supply system S reduces the remaining capacity of the battery 2 before the vehicle enters a long-term stopped period. Then, the supply control device 8 causes the fuel cell 1 to generate electricity using the hydrogen boil-off gas generated while the vehicle is stopped, and supplies the generated electricity to the battery 2 with its reduced remaining capacity. In this way, the battery 2 can charge all of the electricity generated by the fuel cell 1 using the hydrogen boil-off gas generated during the stopped period. As a result, the supply system S can suppress the emission of hydrogen boil-off gas into the atmosphere even when the vehicle is stopped for a long period. The configuration of the supply control device 8 is described below.

[0029] [Configuration of supply control device 8] 2 is a diagram illustrating the configuration of the supply control device 8. The supply control device 8 has a storage unit 81 and a control unit 82. The storage unit 81 is a storage medium including a ROM (Read Only Memory), a RAM (Random Access Memory), a hard disk, etc. The storage unit 81 stores a program executed by the control unit 82.

[0030] The control unit 82 is a computational resource including a processor such as a CPU (Central Processing Unit). The control unit 82 executes the programs stored in the storage unit 81 to realize the functions of an acquisition unit 821, a generation amount prediction unit 822, a power generation amount prediction unit 823, a capacity control unit 824, and a supply control unit 825.

[0031] The acquisition unit 821 acquires scheduled information indicating the stop period. The stop period is a period during which the vehicle equipped with the fuel cell 1 is stopped for a predetermined period of time or longer. The predetermined period may be determined as appropriate, and a specific value is eight hours, but is not limited to this. The acquisition unit 821 acquires scheduled information indicating the stop period from the scheduled stop time when the fuel cell 1 stops operating to the scheduled start time when the fuel cell 1 starts operating, from the external device 9. The external device 9 is, for example, a server of a business operator that manages vehicles equipped with the supply system S.

[0032] FIG. 3 is a data table showing an example of schedule information. In the schedule information, a start time and a stop time are associated with each of a plurality of dates. Furthermore, an actual start time and an actual stop time are associated with each of the plurality of dates. February 5th in FIG. 3 is a holiday for the company that manages the vehicle. In other words, the fuel cell 1 does not operate all day on February 5th and is stopped.

[0033] The acquisition unit 821 acquires the stop period for February 3, for example, after the start time (9:03) on February 3. Specifically, the acquisition unit 821 acquires the schedule information of Fig. 3 from the external device 9, and acquires the period from 5:00 PM, which is the stop time on February 3, to 9:00 AM, which is the start time on February 4, which is shown in the schedule information, as the stop period.

[0034] The acquisition unit 821 may acquire a stop period that has been changed according to the difference between the scheduled stop time and the actual stop time. For example, the acquisition unit 821 changes the stop time on February 3 by the average value (10 minutes) of the differences between the scheduled stop times and the actual stop times on February 1 and February 2, and acquires the period from 5:10 PM on February 3 to 9:00 PM on February 4 as the stop period.

[0035] The acquisition unit 821 can acquire a stop period that has been changed according to the difference between the scheduled start time and the actual start time. For example, the acquisition unit 821 changes the scheduled start time on February 4 by the average value (7 minutes) of the differences between the scheduled start time and the actual start time on February 1, February 2, and February 3, and acquires the period from 17:10 on February 3 to 9:07 on February 4 as the stop period.

[0036] After acquiring the stop period, the acquisition unit 821 acquires a weather forecast that predicts the weather during the stop period. For example, the acquisition unit 821 acquires a weather forecast that predicts the weather for each predetermined hour during the stop period. Specifically, the acquisition unit 821 acquires a weather forecast that predicts the weather, such as sunny, cloudy, or rainy, and the temperature, for each hour in a predetermined space in which the vehicle is located during the stop period. The predetermined space is, for example, the location of the business that manages the vehicle. Specifically, the predetermined space is, but is not limited to, the region, prefecture, or city, ward, town, or village that includes the location of the business. The acquisition unit 821 can acquire the weather forecast from a server managed by a business that forecasts the weather, but the source from which the weather forecast is acquired is not limited to this.

[0037] The generation amount prediction unit 822 is a first prediction unit that predicts the amount of hydrogen boil-off gas generated during the shutdown period. The generation amount prediction unit 822 predicts the unit generation amount of hydrogen boil-off gas per unit time. For example, the generation amount prediction unit 822 predicts the unit generation amount based on the temperature indicated by the weather forecast during the shutdown period in a specified space where the vehicle is located.

[0038] The unit generation amount per unit temperature is stored in the memory unit 81. For example, the memory unit 81 stores a data table that associates each of a plurality of temperatures with the unit generation amount corresponding to each temperature. FIG. 4 is an example of a data table that associates temperatures with unit generation amounts. As shown in FIG. 4, the memory unit 81 stores a data table that associates a higher temperature with a larger unit generation amount.

[0039] The generation amount prediction unit 822 predicts the unit generation amount according to the temperature at each time by referring to the data table in Fig. 4. Fig. 5 is an example of a data table predicting the unit generation amount for each time. To give a specific example, if the temperature in the 17:00 hour is 15 degrees, the generation amount prediction unit 822 predicts that the unit generation amount in the 17:00 hour will be 9 (liters), and if the temperature in the 17:00 hour is 10 degrees, the generation amount prediction unit 822 predicts that the unit generation amount in the 5:00 hour will be 4 (liters).

[0040] The generation amount prediction unit 822 predicts the sum of the unit generation amounts at each time as the amount of hydrogen boil-off gas generated during the shutdown period. When the generation amount prediction unit 822 predicts the unit generation amounts at each time shown in the data table of Figure 5, it predicts that 108 (liters) of hydrogen boil-off gas will be generated during the shutdown period. In this way, the generation amount prediction unit 822 can accurately predict the amount of hydrogen boil-off gas generated during the shutdown period.

[0041] The generation amount prediction unit 822 predicted the unit generation amount according to the temperature at each time. Alternatively, the generation amount prediction unit 822 may predict the generation amount as the product of the unit generation amount and the length of the shutdown period. For example, when a vehicle is stored indoors, such as in a garage, where temperature fluctuations are smaller than outdoors, the generation amount prediction unit 822 predicts the amount of hydrogen boil-off gas generated during the shutdown period as the product of the unit generation amount according to the average temperature at each time during the shutdown period and the length of the shutdown period. Specifically, the generation amount prediction unit 822 predicts the amount of hydrogen boil-off gas generated during the shutdown period as the product (96 liters) of the unit generation amount (6 liters per hour) according to the average temperature (12°C) from 5:00 PM to 9:00 AM in the data table shown in FIG. 5 and the length of the shutdown period (16 hours). This allows the generation amount prediction unit 822 to appropriately predict the amount of hydrogen boil-off gas generated during the shutdown period, even when the vehicle is stored indoors.

[0042] Incidentally, when the vehicle is exposed to sunlight, the amount of heat flowing into the container 6 is greater than when the vehicle is not exposed to sunlight. Therefore, the amount of hydrogen boil-off gas generated increases when the vehicle is exposed to sunlight.

[0043] Therefore, the generation amount prediction unit 822 increases the amount of hydrogen boil-off gas generated when sunlight hits the vehicle compared to the amount generated when sunlight does not hit the vehicle. For example, the generation amount prediction unit 822 increases the unit generation amount during the shutdown period when sunlight hits the vehicle compared to the unit generation amount during the shutdown period when sunlight does not hit the vehicle. The time when sunlight hits the vehicle is the time from sunrise to sunset. The generation amount prediction unit 822 sets the unit generation amount during the time between sunrise and sunset to a value obtained by adding a predetermined amount to the unit generation amount corresponding to the temperature shown in the data table in FIG. 4. The predetermined amount may be determined appropriately through experiments, etc. For example, if the temperature at 10:00 AM on February 5th, a non-business day, is 15 degrees Celsius, the generation amount prediction unit 822 sets the unit generation amount of hydrogen boil-off gas for the 10:00 AM hour to 15 (liters), which is obtained by adding a predetermined amount of 6 (liters) to the unit generation amount of 9 (liters) corresponding to 15 degrees Celsius. In this way, the generation amount prediction unit 822 can predict the generation amount of hydrogen boil-off gas taking into account the influence of sunlight.

[0044] Even if the vehicle is exposed to sunlight at a certain time, if the weather is cloudy or rainy, the vehicle will not be exposed to sunlight. Therefore, the generation amount prediction unit 822 increases the amount of hydrogen boil-off gas generated when the weather is clear compared to the amount of hydrogen boil-off gas generated when the weather is not clear. For example, based on the weather forecast, the generation amount prediction unit 822 increases the unit generation amount for sunny hours during the time period when sunlight is shining on the vehicle compared to the unit generation amount for sunny hours. Specifically, the generation amount prediction unit 822 sets the unit generation amount for sunny hours to a value obtained by adding a predetermined amount to the unit generation amount corresponding to the temperature shown in the data table of FIG. 4. In this way, the generation amount prediction unit 822 can predict an appropriate amount of hydrogen boil-off gas generated depending on the weather.

[0045] The power generation amount prediction unit 823 is a second prediction unit that, after the generation amount has been predicted, predicts the power generation amount of the fuel cell 1 during the shutdown period. The power generation amount prediction unit 823 determines whether or not it is necessary to predict the generation amount depending on whether or not the pressure of the hydrogen boil-off gas in the container 6 becomes higher than a predetermined pressure due to the predicted amount of hydrogen boil-off gas being generated during the shutdown period.

[0046] The power generation amount prediction unit 823 predicts the pressure inside the container 6 during the shutdown period based on the predicted generation amount. For example, the power generation amount prediction unit 823 refers to a data table that associates the generation amount with the amount of pressure increase inside the container 6, and identifies the amount of pressure increase inside the container 6 that corresponds to the predicted generation amount. The power generation amount prediction unit 823 predicts the pressure inside the container 6 during the shutdown period as a value obtained by adding the identified amount of pressure increase to the current pressure inside the container 6. Alternatively, the power generation amount prediction unit 823 may use a value obtained by multiplying the generation amount by a predetermined coefficient as the amount of pressure increase. The predetermined coefficient is expressed, for example, as the product of the temperature of the hydrogen boil-off gas and the gas constant R, relative to the volume of the container 6.

[0047] The power generation amount prediction unit 823 determines whether the predicted pressure inside the container 6 will be greater than a predetermined pressure. If the pressure inside the container 6 is equal to or less than the predetermined pressure, the power generation amount prediction unit 823 does not predict the power generation amount because there is no need to have the fuel cell 1 generate power using hydrogen boil-off gas during the shutdown period. This allows the power generation amount prediction unit 823 to omit unnecessary processing, thereby reducing waste of calculation resources.

[0048] When the pressure inside the container 6 becomes higher than a predetermined pressure, the power generation amount prediction unit 823 predicts the power generation amount corresponding to the predicted generation amount. The power generation amount prediction unit 823 predicts a larger power generation amount as the predicted generation amount becomes larger. Specifically, the power generation amount prediction unit 823 predicts the power generation amount corresponding to the predicted generation amount by referring to a data table that associates the generation amount with the power generation amount that can be generated with that generation amount. Furthermore, the power generation amount prediction unit 823 may predict the power generation amount by inputting the predicted generation amount into a function that outputs the power generation amount when the generation amount is input.

[0049] The capacity control unit 824 is a first control unit that controls the remaining capacity of the battery 2. For example, the capacity control unit 824 increases the remaining capacity of the battery 2 by supplying the power generated by the fuel cell 1 to the battery 2. In addition, the capacity control unit 824 decreases the remaining capacity of the battery 2 by supplying the power stored in the battery 2 to the inverter 3.

[0050] The capacity control unit 824 controls the remaining capacity of the battery 2 depending on whether the predicted amount of power generation is greater than the chargeable amount of the battery 2. The chargeable amount is the amount of power that can be charged to the battery 2. Specifically, the chargeable amount is a value obtained by subtracting the remaining capacity from the maximum capacity of the battery 2. If the predicted amount of power generation is equal to or less than the chargeable amount, the capacity control unit 824 does not control the remaining capacity of the battery 2 because there is no need to reduce the remaining capacity of the battery 2.

[0051] If the predicted power generation amount is greater than the chargeable amount, the capacity control unit 824 reduces the remaining capacity of the battery 2 before the shutdown period begins. Specifically, the capacity control unit 824 reduces the remaining capacity of the battery 2 from the start time indicated in the schedule information until the stop time. More specifically, the capacity control unit 824 reduces the remaining capacity of the battery 2 by supplying the power stored in the battery 2 to the inverter 3 and other devices until the chargeable amount becomes equal to or greater than the predicted power generation amount. Examples of other devices include, but are not limited to, an air conditioner in the vehicle cabin and a refrigerator for cooling the luggage compartment of the vehicle. The capacity control unit 824 supplies power from the battery 2 to the inverter 3 while the vehicle is running, and when the vehicle is stopped, supplies power from the battery 2 to other devices instead of the inverter 3. In this way, the capacity control unit 824 can make the battery 2 chargeable with power generated by the fuel cell 1 using hydrogen boil-off gas generated during the shutdown period.

[0052] The supply control unit 825 is a second control unit that controls the supply and cutoff of hydrogen boil-off gas to the fuel cell 1. After the shutdown period begins, the supply control unit 825 opens the supply valve 71 to supply the hydrogen boil-off gas generated during the shutdown period to the fuel cell 1. The supply control unit 825 keeps the supply valve 71 open during the shutdown period, thereby continuing to supply the hydrogen boil-off gas generated during the shutdown period to the fuel cell 1. The supply control unit 825 supplies the hydrogen boil-off gas to the fuel cell 1, causing the fuel cell 1 to generate power using the hydrogen boil-off gas. As described above, the remaining capacity of the battery 2 decreases until it becomes possible to charge the power generated by the fuel cell 1 using the hydrogen boil-off gas generated during the shutdown period. Therefore, all of the power generated by the fuel cell 1 using the hydrogen boil-off gas generated during the shutdown period is charged to the battery 2. As a result, emission of hydrogen boil-off gas into the atmosphere is suppressed.

[0053] During the shutdown period, supply control unit 825 does not supply liquid hydrogen to vaporization unit 62. Specifically, supply control unit 825 closes valve 70 at the shutdown time or when fuel cell 1 stops operating, thereby blocking liquid hydrogen from flowing from container 6 to vaporization unit 62. After the start time arrives, supply control unit 825 closes supply valve 71 and opens valve 70. In this way, after the vehicle starts, supply control unit 825 allows liquid hydrogen to pass from container 6 to vaporization unit 62, and prevents hydrogen boil-off gas from being supplied to fuel cell 1.

[0054] [Treatment to reduce hydrogen boil-off gas emissions into the atmosphere] 6 is a flowchart showing an example of a process for suppressing discharge of hydrogen boil-off gas into the atmosphere. The process for suppressing discharge of hydrogen boil-off gas into the atmosphere is executed after start-up of the fuel cell 1. It is assumed that, after start-up of the fuel cell 1, the acquisition unit 821 has acquired schedule information indicating the shutdown period and a weather forecast for the shutdown period.

[0055] The generation amount prediction unit 822 predicts the amount of hydrogen boil-off gas generated during the shutdown period (step S1). Specifically, the generation amount prediction unit 822 predicts the unit generation amount based on the temperature indicated by the weather forecast for the specified space where the vehicle is located during the shutdown period, and predicts the value obtained by multiplying the predicted unit generation amount by the length of the shutdown period as the amount of hydrogen boil-off gas generated during the shutdown period.

[0056] The power generation amount prediction unit 823 determines whether the pressure of the predicted amount of hydrogen boil-off gas generated is greater than a predetermined pressure (step S2). The power generation amount prediction unit 823 predicts the pressure inside the container 6 based on the volume of the container 6 and the predicted amount of hydrogen generated, and determines whether the predicted pressure inside the container 6 is greater than a predetermined pressure. If the pressure of the predicted amount of hydrogen boil-off gas generated is equal to or less than the predetermined pressure (No in step S2), the power generation amount prediction unit 823 ends the process because there is no need to have the fuel cell 1 generate electricity using the hydrogen boil-off gas during the shutdown period.

[0057] If the pressure of the hydrogen boil-off gas in the container 6 is higher than the predetermined pressure (Yes in step S2), the power generation amount prediction unit 823 predicts the amount of power that the fuel cell 1 can generate during the shutdown period (step S3). Specifically, the power generation amount prediction unit 823 predicts the amount of power generation corresponding to the predicted amount of generation by referring to a data table that associates the amount of generation with the amount of power generation.

[0058] The capacity control unit 824 determines whether the predicted amount of power generation is greater than the chargeable amount (step S4). If the predicted amount of power generation is equal to or less than the chargeable amount (No in step S4), the capacity control unit 824 proceeds to step S6 because there is no need to reduce the remaining capacity of the battery 2.

[0059] If the predicted power generation amount is greater than the chargeable amount (Yes in step S4), the capacity control unit 824 reduces the remaining capacity of the battery 2 before the suspension period begins (step S5). Specifically, the capacity control unit 824 reduces the remaining capacity of the battery 2 by supplying the power stored in the battery 2 to the inverter 3 until the chargeable amount becomes greater than the predicted power generation amount.

[0060] The supply control unit 825 determines whether or not the stop period has begun (step S6). If the current time is before the stop time indicated in the schedule information (No in step S6), the supply control unit 825 waits until the current time becomes the stop time or later.

[0061] If the current time is after the shutdown time (Yes in step S6), the supply control unit 825 supplies hydrogen boil-off gas to the fuel cell 1, causing the fuel cell 1 to generate electricity (step S7). Specifically, after the shutdown period begins, the supply control unit 825 opens the supply valve 71 to supply the hydrogen boil-off gas generated during the shutdown period to the fuel cell 1.

[0062] (Variation) In the above embodiment, the supply system S has the fuel cell 1 that generates electrical energy as power. However, the supply system S is not limited to this and may also have a hydrogen engine that generates power using hydrogen in addition to the fuel cell 1. A hydrogen engine is an internal combustion engine that burns and expands a mixture of hydrogen and intake air to generate kinetic energy as power. The supply system S supplies the fuel cell 1 with hydrogen boil-off gas that is generated when the hydrogen engine is stopped.

[0063] [Effects of Supply System S] As explained above, if the amount of power that the fuel cell 1 can generate using hydrogen boil-off gas of liquid hydrogen generated during a shutdown period of the fuel cell 1 is greater than the remaining capacity of the battery 2, the supply system S reduces the remaining capacity of the battery 2 before the shutdown period begins. This allows the supply system S to increase the amount of power that can be charged to the battery 2 before the shutdown period begins. As a result, the supply system S becomes able to charge the battery 2 with the power generated by the fuel cell using the hydrogen boil-off gas generated during the shutdown period of the fuel cell 1. In this way, the supply system S allows the fuel cell 1 to consume the hydrogen boil-off gas generated during the shutdown period, thereby suppressing the emission of hydrogen boil-off gas into the atmosphere.

[0064] The present invention has been described above using embodiments, but the technical scope of the present invention is not limited to the scope described in the above embodiments, and various modifications and changes are possible within the scope of the gist of the present invention. For example, all or part of the device can be configured by functionally or physically distributing or integrating any unit. Furthermore, new embodiments resulting from any combination of multiple embodiments are also included in the embodiments of the present invention. The effects of the new embodiments resulting from the combination also have the effects of the original embodiments. [Explanation of symbols]

[0065] S Supply System 1 fuel cell 2 Battery 3 inverters 4 motors 5 Driven equipment 6 containers 8 Supply control device 9 External device 51 Transmission 61 First supply pipe 62 Vaporization section 63 Pressure Sensor 64 Purge line 65 Second supply pipe 70 valves 71 Supply valve 72 Purge valve 81 Storage section 82 Control Unit 821 Acquisition Department 822 Generation Amount Prediction Department 823 Power Generation Forecasting Department 824 Capacity control section 825 Supply control section

Claims

1. A fuel cell that generates electricity using hydrogen boil-off gas vaporized from a container that stores liquid hydrogen; a battery that stores the electricity generated by the fuel cell; a first prediction unit that predicts the amount of hydrogen boil-off gas generated during a shutdown period in which a power unit that generates power using the liquid hydrogen in the container is shut down for a predetermined period of time or longer; a second prediction unit that predicts the amount of power that can be generated by the fuel cell using the generated amount of hydrogen boil-off gas; a first control unit that reduces a remaining capacity of the battery before the stop period begins when the predicted amount of power generated is greater than an amount of power that can be charged to the battery; a second control unit that supplies the hydrogen boil-off gas generated during the shutdown period to the fuel cell, thereby causing the fuel cell to generate power using the hydrogen boil-off gas; A supply system having:

2. the first prediction unit predicts the generation amount as the product of the unit generation amount of the hydrogen boil-off gas per unit time and the length of the shutdown period; The delivery system of claim 1 .

3. the first prediction unit predicts the unit generation amount according to an air temperature during the stop period in a predetermined space where the container is located. The delivery system of claim 2.

4. the first prediction unit sets the amount of generation at a time when sunlight hits an apparatus that mounts the container during the stop period to be greater than the amount of generation at a time when sunlight does not hit the apparatus; The delivery system of claim 1 .

5. the first prediction unit, based on a weather forecast predicting weather during the suspension period, sets the generation amount during a time when the weather is fine to be greater than the generation amount during a time when the weather is not fine, The delivery system of claim 1 .

6. the first control unit reduces the remaining capacity until an amount of power that can be charged into the battery, which is determined by subtracting the remaining capacity from the maximum capacity of the battery, becomes equal to or greater than the predicted amount of power generation. The delivery system of claim 1 .

7. the second prediction unit predicts the amount of power generation when the pressure in the container becomes greater than a predetermined pressure for determining whether or not to discharge the hydrogen boil-off gas in the container due to the generation of the amount of hydrogen boil-off gas during the shutdown period. A supply system according to any one of claims 1 to 6.

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