Power supply system

Abstract

A power supply system (100) according to the present disclosure comprises: a vaporizer (12) that vaporizes liquefied hydrogen (HL) to generate hydrogen gas (HG); at least one fuel cell unit (13) that generates power using the hydrogen gas (HG) supplied from the vaporizer (12); and an exhaust heat recovery path (L3) that guides a fluid (F0) discharged from the at least one fuel cell unit (13) to the vaporizer (12). The vaporizer (12) performs heat exchange between the liquefied hydrogen (HL) and the fluid (F0) to vaporize the liquefied hydrogen (HL).

Description

Power Supply System

[0001] The present disclosure relates to a power supply system.

[0002] Patent Document 1 discloses a pure hydrogen fuel cell system that receives pure hydrogen from an external hydrogen supply source and supplies electricity and heat to the outside.

[0003] JP 2011-054515 A

[0004] The present disclosure provides techniques suitable for reducing the operating costs of a power supply system equipped with a fuel cell.

[0005] The power supply system of the present disclosure comprises: a vaporizer that vaporizes liquefied hydrogen to produce hydrogen gas; at least one fuel cell unit that generates electricity using the hydrogen gas supplied from the vaporizer; and an exhaust heat recovery path that guides a fluid discharged from the at least one fuel cell unit to the vaporizer, wherein the vaporizer vaporizes the liquefied hydrogen by exchanging heat between the liquefied hydrogen and the fluid.

[0006] The technology disclosed herein is suitable for reducing the operating costs of a power supply system equipped with a fuel cell.

[0007] Configuration diagram of a power supply system according to an embodiment. Configuration diagram of a power supply system according to a first modification. Configuration diagram of a power supply system according to a second modification. Configuration diagram of a power supply system according to a third modification.

[0008] (Findings forming the basis of the present disclosure) Pure hydrogen fuel cells that use hydrogen gas as fuel gas are known (for example, see Patent Document 1). The hydrogen gas supplied to pure hydrogen fuel cells is sometimes generated by vaporizing liquefied hydrogen gas using a vaporizer.

[0009] A vaporizer that vaporizes liquefied hydrogen gas requires a heat source fluid for heat exchange with the liquefied hydrogen gas. If the heat source fluid is high-temperature gas or hot water, a device for heating the gas or water is required. Such a device can increase the operating costs of a pure hydrogen fuel cell. If the heat source fluid is room-temperature air (atmospheric air), the vaporizer becomes larger. This can increase the costs required for the vaporizer.

[0010] Therefore, the present inventors have investigated techniques suitable for reducing the operating costs of a power supply system equipped with a fuel cell.

[0011] Hereinafter, embodiments will be described in detail with reference to the drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters or redundant descriptions of substantially identical configurations may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art.

[0012] The accompanying drawings and the following description are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter recited in the claims.

[0013] (Embodiment) Hereinafter, an embodiment will be described with reference to Figs.

[0014] [1-1. Configuration] Fig. 1 is a configuration diagram of a power supply system 100 according to this embodiment. The power supply system 100 includes a vaporizer 12, a fuel cell unit 13, and an exhaust heat recovery path L3. The vaporizer 12 vaporizes liquefied hydrogen HL to generate hydrogen gas HG. The fuel cell unit 13 generates power using the hydrogen gas HG supplied from the vaporizer 12. The exhaust heat recovery path L3 guides the fluid F0 discharged from the fuel cell unit 13 to the vaporizer 12. The vaporizer 12 vaporizes the liquefied hydrogen HL by heat exchange with the fluid F0. This generates hydrogen gas HG.

[0015] In power supply system 100, fluid F0 discharged from fuel cell unit 13 can be used as a heat source fluid for vaporizer 12, and the exhaust heat from fuel cell unit 13 can be used to vaporize liquefied hydrogen HL to produce hydrogen gas HG. This eliminates the need for a separate device to heat the gas or water used as the heat source fluid for vaporizer 12, thereby reducing the operating costs of power supply system 100. For the same reason, power supply system 100 is also suitable for miniaturizing the entire system and reducing the space required to install the system.

[0016] The greater the amount of power generated by the fuel cell unit 13, the greater the amount of heat exhausted from the fuel cell unit 13. Furthermore, the greater the amount of power generated by the fuel cell unit 13, the greater the amount of hydrogen gas HG required, and therefore the greater the amount of liquefied hydrogen HL that must be vaporized. In the power supply system 100, by utilizing the exhaust heat of the fuel cell unit 13, the fuel cell unit 13 can be made to generate power efficiently, even when the amount of power generated by the fuel cell unit 13 is large. Furthermore, during periods when the outside temperature is particularly low, such as in winter, the amount of heat required to vaporize the liquefied hydrogen HL increases. According to the power supply system 100, by utilizing the exhaust heat of the fuel cell unit 13, the fuel cell unit 13 can be made to generate power efficiently, even during such periods.

[0017] The hydrogen gas HG is pure hydrogen gas. The fuel cell unit 13 is a pure hydrogen type that uses pure hydrogen gas as fuel gas. Pure hydrogen gas is a gas that is substantially composed of hydrogen (H), and may contain unavoidable impurities.

[0018] The power supply system 100 may further include a hydrogen tank 11 that stores liquefied hydrogen HL. The vaporizer 12 may vaporize the liquefied hydrogen HL supplied from the hydrogen tank 11 to generate hydrogen gas HG.

[0019] The power supply system 100 may further include a liquefied hydrogen supply path L1 and a hydrogen gas supply path L2. The liquefied hydrogen supply path L1 may guide the liquefied hydrogen HL discharged from the hydrogen tank 11 to the vaporizer 12. The hydrogen gas supply path L2 may guide the hydrogen gas HG discharged from the vaporizer 12 to the fuel cell unit 13.

[0020] The fuel cell unit 13 includes a fuel cell stack 13a and a power conversion device 13b. The power conversion device 13b may include a DC-DC converter and a DC-AC inverter. The fuel cell stack 13a generates electricity by receiving anode gas and cathode gas. The anode gas is hydrogen gas (HG). The cathode gas is an oxygen-containing gas such as air. Examples of fuel cells include polymer electrolyte fuel cells (PEFCs) and solid oxide fuel cells (SOFCs). PEFCs are low-temperature operating fuel cells with an operating temperature of approximately 80°C. SOFCs are high-temperature operating fuel cells with an operating temperature of approximately 700°C.

[0021] The fluid F0 discharged from the fuel cell unit 13 may be a gas, a liquid, or a two-phase flow containing a gas and a liquid. The fluid F0 discharged from the fuel cell unit 13 may be a high-temperature gas or hot water. Both high-temperature gas and hot water may be used as the fluid F0. In this case, the exhaust heat recovery path L3 may have a first portion for guiding the high-temperature gas and a second portion for guiding the hot water.

[0022] The hot water as the fluid F0 may be waste heat recovery water that recovers heat generated in the fuel cell stack 13a, or may be excess water generated by the electrochemical reaction in the fuel cell stack 13a.

[0023] The high-temperature gas serving as fluid F0 is not particularly limited as long as it is gas discharged from the fuel cell unit 13. The high-temperature gas serving as fluid F0 may be, for example, air that was filled in the housing that accommodates the fuel cell stack 13a and that was discharged from the housing for ventilation. The high-temperature gas serving as fluid F0 may be anode off-gas or cathode off-gas discharged from the fuel cell unit 13. The anode off-gas is discharged from the anode of the fuel cell stack 13a. The cathode off-gas is discharged from the cathode of the fuel cell stack 13a. The anode off-gas and the cathode off-gas may contain moisture. The fluid F0 may also be exhaust gas generated when the solid electrolyte of the SOFC is heated.

[0024] Although the temperature of the fluid generated in the fuel cell unit 13 may vary depending on the type of fuel cell stack 13a, the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 may be in the range of 40°C or higher and lower than 100°C. This allows the liquefied hydrogen HL to be sufficiently vaporized. Furthermore, by keeping the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 within the above numerical range, the cost required for the piping and the like that form the exhaust heat recovery path L3 can be reduced.

[0025] For example, if the fuel cell stack 13a is a high-temperature operating SOFC, the fluid generated in the fuel cell unit 13 may be adjusted to a temperature in the range of 40°C or higher and lower than 100°C before being discharged from the fuel cell unit 13.

[0026] The temperature of the fluid F0 flowing through the exhaust heat recovery path L3 may be in the range of 50°C or higher and 70°C or lower.

[0027] Although not shown, the power supply system 100 may further include a pump for sending the fluid F0 to the vaporizer 12. The pump may be provided in the exhaust heat recovery path L3 or in the fuel cell unit 13.

[0028] The power supply system 100 may further include a controller 30. The controller 30 may control the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 so that it is in a range of 40°C or higher and lower than 100°C. The controller 30 may, for example, increase or decrease the rotation speed of a cooling path (not shown) of the fuel cell stack 13a or a pump (not shown) provided in the exhaust heat recovery path L3 so that the fuel cell stack 13a reaches an appropriate operating temperature. As a result, the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 may be controlled to be in a range of 40°C or higher and lower than 100°C.

[0029] The flow rate of the fluid F0 flowing through the exhaust heat recovery path L3 may be controlled by the controller 30. For example, the controller 30 receives a detected value of the flow rate of the fluid F0 flowing through the exhaust heat recovery path L3 from a flow rate sensor (not shown) provided in the exhaust heat recovery path L3, and increases or decreases the rotation speed of a pump (not shown) provided in the exhaust heat recovery path L3.

[0030] When both high-temperature gas and hot water are used as the fluid F0, the controller 30 may control the flow rate of the high-temperature gas flowing through the first part of the exhaust heat recovery path L3 and the flow rate of the hot water flowing through the second part of the exhaust heat recovery path L3.

[0031] The controller 30 is a computer that includes, for example, a storage device that stores programs necessary for increasing or decreasing the rotation speed of a fan or a pump, and a processor that reads and executes the programs from the storage device.

[0032] (Variation 1) Figure 2 is a configuration diagram of a power supply system 101 in Variation 1 of the above embodiment. The power supply system 101 in Variation 1 has the same configuration as the power supply system 100 in the above embodiment, except that the fluid F1 discharged from the vaporizer 12 is used to cool the fuel cell unit 13. Therefore, in Figure 2, the same components as those in the power supply system 100 are denoted by the same reference numerals, and detailed descriptions thereof will be omitted.

[0033] The fluid F0 introduced into the vaporizer 12 is cooled by heat exchange with the liquefied hydrogen HL and discharged from the vaporizer 12. According to the power supply system 101, the fuel cell unit 13 can be cooled by the heat of vaporization of the liquefied hydrogen HL using the fluid F1 discharged from the vaporizer 12. This eliminates the need to provide a separate cooling device using a cooling medium to cool the fuel cell unit 13, thereby reducing the operating costs of the power supply system 101. For the same reason, the power supply system 101 is also suitable for reducing the overall system size and the space required to install the system. Furthermore, according to the power supply system 101, temperature increases in the fuel cell stack 13a and the power conversion device 13b can be suppressed, thereby ensuring the durability of these devices and ensuring operational safety.

[0034] The lower the temperature of the fluid F1 supplied to the fuel cell unit 13, the more efficient the exhaust heat recovery in the fuel cell unit 13. This is because, when the heat generation amount of the fuel cell stack 13a is constant and the temperature of the fuel cell stack 13a is controlled to be constant, the lower the temperature of the fluid F1, the smaller the flow rate of the fluid F1 supplied to the fuel cell unit 13 and the higher the temperature of the fluid F0 discharged from the fuel cell unit 13. Therefore, the lower the temperature of the fluid F1 supplied to the fuel cell unit 13, the higher the efficiency of the entire power supply system 101. Furthermore, the lower the temperature of the fluid F1 relative to the temperature of the fuel cell stack 13a, i.e., the larger the temperature difference, the better the heat exchange performance and therefore the higher the efficiency.

[0035] The power supply system 101 may further include a first cooling path L4 that guides the fluid F1 discharged from the vaporizer 12 to the fuel cell unit 13. The fluid F1 discharged from the vaporizer 12 may be guided to the fuel cell unit 13 by the first cooling path L4.

[0036] The temperature of the fluid after heat exchange generated in the vaporizer 12 may vary depending on the temperature of the fluid F0 introduced into the vaporizer 12, but the temperature of the fluid F1 after heat exchange discharged from the vaporizer 12 may be in the range of 0° C. to 50° C. This allows the fluid F1 to sufficiently cool the fuel cell unit 13.

[0037] The temperature of the fluid F1 flowing through the first cooling path L4 may be in the range of 0°C or higher and 50°C or lower.

[0038] The temperature of the fluid F1 flowing through the first cooling path L4 may be in the range of 10°C or higher and 40°C or lower.

[0039] The controller 30 may control the temperature of the fluid F1 flowing through the first cooling path L4 to be in the range of 0° C. or higher and 50° C. or lower. The controller 30 receives, for example, a detected value of the temperature of the fluid F1 flowing through the first cooling path L4 from a temperature sensor (not shown) provided in the first cooling path L4, and increases or decreases the rotation speed of a fan (not shown) provided in the evaporator 12 or a pump (not shown) provided in the exhaust heat recovery path L3 so that the detected value of the temperature sensor follows a target value (0° C. or higher and 50° C. or lower).

[0040] The flow rate of the fluid F1 flowing through the first cooling path L4 may be controlled by the controller 30. For example, the controller 30 receives a detected value of the flow rate of the fluid F1 flowing through the first cooling path L4 from a flow rate sensor (not shown) provided in the first cooling path L4, and increases or decreases the rotation speed of a pump (not shown) provided in the first cooling path L4.

[0041] The fluids F0 and F1 are typically cooling media (particularly, cooling water) for the fuel cell unit 13. The cooling media for the fuel cell unit 13 may circulate through the fuel cell unit 13, the exhaust heat recovery path L3, the evaporator 12, and the first cooling path L4. In this case, the exhaust heat recovery path L3 and the first cooling path L4 may be circulation circuits for the cooling water for the fuel cell unit 13.

[0042] (Modification 2) Fig. 3 is a configuration diagram of a power supply system 102 in Modification 2 of the above embodiment. The power supply system 102 in Modification 2 has the same configuration as the power supply system 100 of the above embodiment, except that it further includes a photovoltaic power generation module 21 and the fluid F1 discharged from the vaporizer 12 is used to cool the photovoltaic power generation module 21. Therefore, in Fig. 3, the same components as those in the power supply system 100 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0043] If the temperature of the photovoltaic power generation module 21 becomes too high, the power generation efficiency of the photovoltaic power generation module 21 tends to decrease. According to the power supply system 102, the photovoltaic power generation module 21 can be cooled by the heat of vaporization of the liquefied hydrogen HL using the heat-exchanged fluid F1 discharged from the vaporizer 12. Therefore, the temperature rise of the photovoltaic power generation module 21 can be suppressed, for example, during periods when the outside air temperature is particularly high, such as in summer. Furthermore, since there is no need to separately install a cooling device using a cooling medium to cool the photovoltaic power generation module 21, the operating costs of the power supply system 102 can be reduced. For the same reason, the power supply system 102 is also suitable for miniaturizing the entire system and reducing the space required for installing the system. Furthermore, during periods when the amount of solar radiation is particularly low, such as in winter, the amount of power generated by the photovoltaic power generation module 21 decreases. The power supply system 102 can link fuel cells and photovoltaic power generation, thereby achieving high efficiency as a whole system.

[0044] The power supply system 102 may further include a second cooling path L5 that guides the fluid F1 discharged from the vaporizer 12 to the photovoltaic power generation module 21. The fluid F1 discharged from the vaporizer 12 may be guided to the photovoltaic power generation module 21 by the second cooling path L5.

[0045] In the power supply system 102, the temperature of the fluid F1 flowing through the second cooling path L5 may be in the same numerical range as the temperature of the fluid F1 flowing through the first cooling path L4 of the power supply system 101. That is, the temperature of the fluid F1 flowing through the second cooling path L5 may be in the range of 0°C or higher and 50°C or lower.

[0046] The controller 30 may control the temperature of the fluid F1 flowing through the second cooling path L5 to be in the range of 0° C. or higher and 50° C. or lower. The controller 30 receives, for example, a detection value of the temperature of the fluid F1 flowing through the second cooling path L5 from a temperature sensor (not shown) provided in the second cooling path L5, and increases or decreases the rotation speed of a fan (not shown) provided in the evaporator 12 so that the detection value of the temperature sensor follows a target value (0° C. or higher and 50° C. or lower).

[0047] The flow rate of the fluid F1 flowing through the second cooling path L5 may be controlled by the controller 30. For example, the controller 30 receives a detected value of the flow rate of the fluid F1 flowing through the second cooling path L5 from a flow rate sensor (not shown) provided in the second cooling path L5, and increases or decreases the rotation speed of a pump (not shown) provided in the second cooling path L5.

[0048] Although not shown, the power supply system 102 may further include a power conversion device connected to the solar power generation module 21. The power conversion device may include a DC-DC converter and a DC-AC inverter.

[0049] (Variation 3) Figure 4 is a configuration diagram of a power supply system 103 in Variation 3 of the above-described embodiment. The power supply system 103 in Variation 3 includes a plurality of fuel cell units 13, and has the same configuration as the power supply system 100 in the above-described embodiment, except that the exhaust heat recovery path L3 guides the fluid F0 discharged from each of the plurality of fuel cell units 13 to the vaporizer 12. Therefore, in Figure 4, the same components as those in the power supply system 100 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0050] In the power supply system 103, the fluid F0 discharged from each of the multiple fuel cell units 13 can be used as a heat source fluid for the vaporizer 12. This reduces the operating costs of the power supply system 103. The power supply system 103 is also suitable for reducing the size of the entire system and the space required to install the system. Furthermore, the power supply system 103 allows the overall power generation capacity of the fuel cell units 13 to be flexibly set by adjusting the number of fuel cell units 13.

[0051] In the example shown in Fig. 4, the power supply system 103 includes a plurality of fuel cell units 131, 132, ... 13n. The exhaust heat recovery path L3 combines the fluid F0 discharged from each of the plurality of fuel cell units 131, 132, ... 13n and guides the collected fluid F0 to the vaporizer 12. In the example shown in Fig. 4, n is an arbitrary natural number equal to or greater than 3. The same applies to the other elements described below.

[0052] The power supply system 103 may include a plurality of sub-recovery paths that merge with the exhaust heat recovery path L3 so as to guide the fluid F0 discharged from each of the plurality of fuel cell units 131, 132, . . . 13n to the vaporizer 12.

[0053] 4, the fluid F0 discharged from the fuel cell unit 131 passes through the sub-recovery path L31 and merges with the exhaust heat recovery path L3. The fluid F0 discharged from the fuel cell unit 132 passes through the sub-recovery path L32 and merges with the exhaust heat recovery path L3. The fluid F0 discharged from the fuel cell unit 13n passes through the sub-recovery path L3n and merges with the exhaust heat recovery path L3.

[0054] The controller 30 may control the temperature of the fluid F0 flowing through each of the sub-recovery paths L31, L32, ... L3n so that it is in a range of 40° C. or more and less than 100° C. For example, the controller 30 receives detected values ​​of the temperature of the fluid F0 flowing through each of the sub-recovery paths L31, L32, ... L3n from temperature sensors (not shown) provided in each of the sub-recovery paths L31, L32, ... L3n, and increases or decreases the rotation speed of a fan (not shown) provided in the fuel cell unit 13 so that the detected value of each temperature sensor follows a target value (40° C. or more and less than 100° C.).

[0055] The flow rate of the fluid F0 flowing through each of the sub-recovery paths L31, L32, ..., L3n may be controlled by the controller 30. For example, the controller 30 receives a detected value of the flow rate of the fluid F0 flowing through each of the sub-recovery paths L31, L32, ..., L3n from a flow rate sensor (not shown) provided in each of the sub-recovery paths L31, L32, ..., L3n, and increases or decreases the rotation speed of a pump (not shown) provided in the exhaust heat recovery path L3.

[0056] The power supply system 103 may include a plurality of sub-supply paths branching from the hydrogen gas supply path L2 so as to supply hydrogen gas HG to each of the plurality of fuel cell units 131, 132, . . . 13n.

[0057] 4, the hydrogen gas HG flowing through the hydrogen gas supply path L2 is supplied to the fuel cell unit 131 via a sub-supply path L21. The hydrogen gas HG flowing through the hydrogen gas supply path L2 is supplied to the fuel cell unit 132 via a sub-supply path L22. The hydrogen gas HG flowing through the hydrogen gas supply path L2 is supplied to the fuel cell unit 13n via a sub-supply path L2n.

[0058] In the power supply system 103, the fluid F1 discharged from the vaporizer 12 may be used to cool each of the multiple fuel cell units 13. With this configuration, the fluid F1 discharged from the vaporizer 12 after heat exchange can be distributed to cool each of the multiple fuel cell units 13. This eliminates the need to provide a separate cooling device that uses a cooling medium to cool the multiple fuel cell units 13, thereby reducing the operating costs of the power supply system 103. The power supply system 103 is also suitable for miniaturizing the entire system and reducing the space required to install the system.

[0059] As shown in FIG. 4, the power supply system 103 may further include a first cooling path L4 that guides the fluid F1 discharged from the vaporizer 12 to the plurality of fuel cell units 13.

[0060] The power supply system 103 may include a plurality of sub-cooling paths branching from the first cooling path L4 so as to supply the fluid F1 to each of the plurality of fuel cell units 131, 132, . . . 13n.

[0061] 4, the fluid F1 flowing through the first cooling path L4 is supplied to the fuel cell unit 131 via a sub-cooling path L41. The fluid F1 flowing through the first cooling path L4 is supplied to the fuel cell unit 132 via a sub-cooling path L42. The fluid F1 flowing through the first cooling path L4 is supplied to the fuel cell unit 13n via a sub-cooling path L4n.

[0062] The controller 30 may control the temperature of the fluid F1 flowing through each of the sub-cooling paths L41, L42, ..., L4n so that it is within a range of 0° C. or more and 50° C. or less. The controller 30 receives, for example, detection values ​​of the temperatures of the fluid F1 flowing through each of the sub-cooling paths L41, L42, ..., L4n from temperature sensors (not shown) provided in each of the sub-cooling paths L41, L42, ..., L4n, and increases or decreases the rotation speed of a fan (not shown) provided in the evaporator 12 so that the detection values ​​of the temperature sensors follow a target value (0° C. or more and 50° C. or less).

[0063] The flow rate of the fluid F1 flowing through each of the sub-cooling paths L41, L42, ..., L4n may be controlled by the controller 30. For example, the controller 30 receives a detected value of the flow rate of the fluid F1 flowing through each of the sub-cooling paths L41, L42, ..., L4n from a flow rate sensor (not shown) provided in each of the sub-cooling paths L41, L42, ..., L4n, and increases or decreases the rotation speed of a pump (not shown) provided in the first cooling path L4.

[0064] 4, the power supply system 103 includes three or more fuel cell units 13, but the number of fuel cell units 13 is not limited to three or more. The number of fuel cell units 13 may be, for example, two.

[0065] [1-2. Operation] The operation and function of the power supply systems 100, 101, 102, and 103 according to the present embodiment configured as described above will be described below with reference to FIGS.

[0066] In the power supply system 100, in the fuel cell stack 13a of the fuel cell unit 13, DC power is generated by an electrochemical reaction between hydrogen gas HG as an anode gas and an oxygen-containing gas as a cathode gas, both of which are supplied from the vaporizer 12. The DC power generated in the fuel cell stack 13a is converted to AC power by the power converter 13b and supplied to a load (not shown).

[0067] As shown in FIG. 1 , a fluid F0 is discharged from the fuel cell unit 13 during operation. The fluid F0 may be a gas, a liquid, or a two-phase flow containing a gas and a liquid. The fluid F0 may be a high-temperature gas or hot water. The high-temperature gas serving as the fluid F0 may be anode off-gas or cathode off-gas generated by an electrochemical reaction in the fuel cell stack 13a. The high-temperature gas serving as the fluid F0 may be air filled in the housing of the fuel cell stack 13a. The hot water serving as the fluid F0 may be exhaust heat recovery water that recovers heat generated in the fuel cell stack 13a. The hot water serving as the fluid F0 may be excess water generated by the electrochemical reaction in the fuel cell stack 13a.

[0068] The fluid F0 discharged from the fuel cell unit 13 is supplied to the vaporizer 12 via an exhaust heat recovery path L3. In the vaporizer 12, heat is exchanged between the liquefied hydrogen HL and the fluid F0, and the liquefied hydrogen HL is vaporized. This produces hydrogen gas HG. The liquefied hydrogen HL may be supplied to the vaporizer 12 from the hydrogen tank 11 via a liquefied hydrogen supply path L1.

[0069] The hydrogen gas HG discharged from the vaporizer 12 may be supplied to the fuel cell unit 13 via a hydrogen gas supply path L2. In the fuel cell stack 13a of the fuel cell unit 13, DC power is generated using the hydrogen gas HG.

[0070] 2, in a power supply system 101 according to the first modification, the fluid F0 introduced into the vaporizer 12 is cooled by heat exchange with the liquefied hydrogen HL and is then discharged from the vaporizer 12. The fluid F1 discharged from the vaporizer 12 is used to cool the fuel cell unit 13. As a result, the fuel cell unit 13 is cooled by the heat of vaporization of the liquefied hydrogen HL.

[0071] The fluid F1 discharged from the vaporizer 12 may be supplied to the fuel cell unit 13 via a first cooling path L4.

[0072] 3 , in a power supply system 102 according to a second modification, the fluid F1 after heat exchange discharged from the vaporizer 12 is used to cool the photovoltaic power generation module 21. As a result, the photovoltaic power generation module 21 is cooled by the heat of vaporization of the liquefied hydrogen HL.

[0073] The fluid F1 discharged from the vaporizer 12 may be supplied to the photovoltaic power generation module 21 via a second cooling path L5.

[0074] 4, in a power supply system 103 according to a third modification, a fluid F0 is discharged from each of the plurality of fuel cell units 131, 132, ... 13n in operation. The fluid F0 discharged from each of the plurality of fuel cell units 131, 132, ... 13n is supplied to the vaporizer 12 via an exhaust heat recovery path L3. In the vaporizer 12, heat is exchanged between the liquefied hydrogen HL and the fluid F0, and the liquefied hydrogen HL is vaporized. As a result, hydrogen gas HG is produced.

[0075] The fluid F0 discharged from the fuel cell unit 131 may merge with the exhaust heat recovery path L3 via the sub-recovery path L31. The fluid F0 discharged from the fuel cell unit 132 may merge with the exhaust heat recovery path L3 via the sub-recovery path L32. The fluid F0 discharged from the fuel cell unit 13n may merge with the exhaust heat recovery path L3 via the sub-recovery path L3n. The exhaust heat recovery path L3 may combine the fluid F0 discharged from each of the multiple fuel cell units 131, 132, ... 13n and guide it to the vaporizer 12.

[0076] The hydrogen gas HG discharged from the vaporizer 12 may be distributed to each of the plurality of fuel cell units 131, 132, ... 13n via a hydrogen gas supply path L2. The hydrogen gas HG may be supplied to the fuel cell unit 131 via a sub-supply path L21 branching off from the hydrogen gas supply path L2. The hydrogen gas HG may be supplied to the fuel cell unit 132 via a sub-supply path L22 branching off from the hydrogen gas supply path L2. The hydrogen gas HG may be supplied to the fuel cell unit 13n via a sub-supply path L2n branching off from the hydrogen gas supply path L2. In each of the fuel cell stacks 13a of the plurality of fuel cell units 131, 132, ... 13n, DC power is generated using the hydrogen gas HG.

[0077] In the power supply system 103 of the third modification, the fluid F1 after heat exchange discharged from the vaporizer 12 may be used to cool each of the plurality of fuel cell units 131, 132, ..., 13n. In this way, each of the plurality of fuel cell units 131, 132, ..., 13n may be cooled by the heat of vaporization of the liquefied hydrogen HL.

[0078] The fluid F1 discharged from the vaporizer 12 may be supplied to each of the plurality of fuel cell units 131, 132, ... 13n via a first cooling path L4. The fluid F1 may be supplied to the fuel cell unit 131 via a sub-cooling path L41 branching off from the first cooling path L4. The fluid F1 may be supplied to the fuel cell unit 132 via a sub-cooling path L42 branching off from the first cooling path L4. The fluid F1 may be supplied to the fuel cell unit 13n via a sub-cooling path L4n branching off from the first cooling path L4.

[0079] [1-3. Effects, etc.] As described above, in this embodiment, power supply systems 100, 101, 102, 103 include vaporizer 12 that vaporizes liquefied hydrogen HL to produce hydrogen gas HG, at least one fuel cell unit 13 that generates electricity using the hydrogen gas HG supplied from vaporizer 12, and exhaust heat recovery path L3 that guides fluid F0 discharged from at least one fuel cell unit 13 to vaporizer 12, and vaporizer 12 vaporizes the liquefied hydrogen HL by exchanging heat between the liquefied hydrogen HL and the fluid F0.

[0080] This allows the fluid F0 discharged from fuel cell unit 13 to be used as a heat source fluid for vaporizer 12, and the exhaust heat from fuel cell unit 13 can be used to vaporize liquefied hydrogen HL to produce hydrogen gas HG. Therefore, there is no need to provide a separate device for heating the gas or water that serves as the heat source fluid for vaporizer 12, thereby reducing the operating costs of power supply system 100.

[0081] In this embodiment, the fluid F1 discharged from the vaporizer 12 may be used to cool at least one fuel cell unit 13 .

[0082] This eliminates the need to provide a separate cooling device that uses a cooling medium to cool the fuel cell unit 13, and reduces the operating costs of the power supply system 101.

[0083] In this embodiment, the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 may be in the range of 40°C or higher and lower than 100°C.

[0084] This allows the liquefied hydrogen HL to be sufficiently vaporized. Furthermore, since the temperature of the fluid F0 flowing through the exhaust heat recovery path L3 is within the above-mentioned range, the cost required for the piping and the like that form the exhaust heat recovery path L3 can be reduced.

[0085] In addition, in this embodiment, at least one fuel cell unit 13 may include multiple fuel cell units 13, and the exhaust heat recovery path L3 may guide the fluid F0 discharged from each of the multiple fuel cell units 13 to the vaporizer 12.

[0086] This reduces the operating costs of the power supply system. Such a power supply system is also suitable for downsizing the entire system and reducing the space required to install the system. In addition, the total power generation capacity of the fuel cell units 13 can be flexibly set by adjusting the number of fuel cell units 13.

[0087] In addition, in this embodiment, a photovoltaic power generation module 21 may be further provided, and the fluid F1 discharged from the vaporizer 12 may be used to cool the photovoltaic power generation module 21 .

[0088] This makes it possible to suppress a rise in temperature of the photovoltaic power generation module 21 during periods when the outside air temperature is particularly high, such as in summer. Furthermore, there is no need to provide a separate cooling device that uses a cooling medium to cool the photovoltaic power generation module 21, which reduces the operating costs of the power supply system.

[0089] (Other Embodiments) As described above, the embodiments have been described as examples of the technology disclosed in this application. However, the technology in this disclosure is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made. Furthermore, it is also possible to combine the components described in the above embodiments to create new embodiments.

[0090] For example, by combining the power supply system 101 in the above-described first modification with the power supply system 102 in the above-described second modification, the fluid F1 discharged from the vaporizer 12 may be used to cool both the fuel cell unit 13 and the photovoltaic power generation module 21. In this case, gas as the fluid F1 may be used to cool the fuel cell unit 13, and water as the fluid F1 may be used to cool the photovoltaic power generation module 21. Water as the fluid F1 may be used to cool the fuel cell unit 13, and gas as the fluid F1 may be used to cool the photovoltaic power generation module 21.

[0091] In the example described above, the power supply system includes one vaporizer 12, but the number of vaporizers 12 included in the power supply system is not limited to one. The power supply system may also include multiple vaporizers 12. For example, the power supply system may be configured to include two vaporizers 12 connected in series, with the fluid F0 discharged from the fuel cell unit 13 being supplied to the first vaporizer 12 to heat the liquefied hydrogen HL, and the heat source fluid being supplied to the second vaporizer 12 from an element other than the fuel cell unit 13, thereby completing the vaporization of the liquefied hydrogen HL. This configuration can also reduce the operating costs of the power supply system.

[0092] Furthermore, the example described above does not limit the operating method of the power supply system in this embodiment. For example, when a large amount of liquefied hydrogen HL is introduced into the vaporizer 12, the fluid F0 discharged from the fuel cell unit 13 may be used as the heat source fluid, whereas when a small amount of liquefied hydrogen HL is introduced into the vaporizer 12, room temperature air (atmospheric air) may be used as the heat source fluid.

[0093] Each of the paths L1, L2, L3, L4, etc. can be configured by one or more pipes.

[0094] The technology disclosed herein is applicable to a system that supplies power by linking fuel cells and solar power generation, and is applicable to, for example, environmental protection initiatives such as RE100 (Renewable Energy 100%).

Claims

1. A power supply system comprising: a vaporizer that vaporizes liquefied hydrogen to produce hydrogen gas; at least one fuel cell unit that generates electricity using the hydrogen gas supplied from the vaporizer; and an exhaust heat recovery path that guides a fluid discharged from the at least one fuel cell unit to the vaporizer, wherein the vaporizer vaporizes the liquefied hydrogen by exchanging heat between the liquefied hydrogen and the fluid.

2. The power supply system of claim 1, wherein the fluid discharged from the vaporizer is used to cool the at least one fuel cell unit.

3. The power supply system according to claim 1 or 2, wherein the temperature of the fluid flowing through the exhaust heat recovery path is in the range of 40°C or higher and lower than 100°C.

4. A power supply system as described in any one of claims 1 to 3, wherein the at least one fuel cell unit includes a plurality of the fuel cell units, and the exhaust heat recovery path guides the fluid discharged from each of the plurality of fuel cell units to the evaporator.

5. The power supply system according to any one of claims 1 to 4, further comprising a solar power generation module, wherein the fluid discharged from the evaporator is used to cool the solar power generation module.

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