CUNNINGHAM ANDREW (GB)
ELMER THEO (GB)
ROBINSON THOMAS (GB)
STRATFORD JEREMY (GB)
GARCIA PABLO ET AL: "ANFIS-Based Control of a Grid-Connected Hybrid System Integrating Renewable Energies, Hydrogen and Batteries", IEEE TRANSACTIONS ON INDUSTRIAL INFORMATICS, IEEE SERVICE CENTER, NEW YORK, NY, US, vol. 10, no. 2, 1 May 2014 (2014-05-01), pages 1107 - 1117, XP011547214, ISSN: 1551-3203, [retrieved on 20140502], DOI: 10.1109/TII.2013.2290069
Claims 1. A controller for a power generation system, wherein the power generation system comprises: a power outlet, a fuel cell that is configured to selectively provide power for the power outlet; a battery that is configured to selectively provide power for the power outlet; and an inverter for converting a DC voltage that is provided by the fuel cell into an inverter-AC-voltage for providing to the power outlet; wherein the controller is configured to: receive a system-load-signal that represents the amount of power that is required by an external load that is connected to the power outlet; receive one or more fuel-cell-parameters that represent one or more operating parameters of the fuel cell; and provide a fuel-cell-power-control-signal based on the system-load-signal and the one or more fuel-cell-parameters, wherein the fuel-cell-power-control- signal is for setting a control-parameter of the fuel cell and / or is for setting a control parameter of the inverter. 2. The controller of claim 1, wherein the controller is further configured to: receive a battery-charge-signal that represents a level of charge of the battery; and provide the fuel-cell-power-control-signal also based on the battery- charge-signal. 3. The controller of claim 1 or claim 2, wherein the controller is configured to: determine a fuel-cell-target-value based on the system-load-signal and the battery-charge-signal, wherein the fuel-cell-target-current represents a target level for the fuel cell; and set the fuel-cell-power-control-signal based on the fuel-cell-target- value. 4. The controller of claim 3, wherein the fuel cell is configured to provide power for the power outlet and also charge the battery. 5. The controller of claim 3, wherein the power generation system further includes: a grid-supply-connector for receiving a grid supply power; wherein the controller is further configured to: receive a grid-supply-signal that represents a power level of the grid supply; and determine the fuel-cell-target-level also based on the grid-supply-signal. 6. The controller of any one of claims 1 to 3, wherein the power generation system further includes: a grid-supply-connector for receiving a grid supply power; wherein the controller is further configured to: receive a grid-supply-characteristic-signal that represents a characteristic of the grid supply; and provide the fuel-cell-power-control-signal also based on the grid-supply- characteristic-signal. 7. The controller of claim 6, wherein: the grid-supply-characteristic-signal comprises a grid-supply-power- level that represents a power level of the grid supply; and the controller is configured to: determine a supply-threshold based on the system-load-signal; compare the grid-supply-power-level with the supply-threshold; and if the grid-supply-power-level is less than the supply-threshold, then set the fuel-cell-power-control-signal such that the fuel cell provides power for the power outlet; or if the grid-supply-voltage-level is greater than or equal to the supply-threshold, then set the fuel-cell-power-control-signal such that the fuel cell does not provide power for the power outlet. 8. The controller of claim 7, wherein the controller is configured to: determine a fuel-cell-target-current based on the difference between the grid-supply-power-level and the supply-threshold; and if the grid-supply-power-level is less than the supply-threshold, then set the fuel-cell-power-control-signal based on the fuel-cell-target-current. 9. A power generation system comprising: the controller of any preceding claim; a power outlet a fuel cell; a grid-supply-connector for receiving a grid supply voltage; an uninterruptable power supply, UPS, that has: a grid-input terminal, a power-output-terminal and a battery-connection-terminal, wherein: the grid-input terminal is connected to the grid-supply-connector, the power-output-terminal is connected to the power outlet; and the battery-connection-terminal is connected to the battery. 10. The power generation system of claim 9, wherein the fuel cell is configured to provide power to the power outlet. 11. The power generation system of claim 9, wherein the fuel cell is configured to provide power to charge the battery. 12. The power generation system of claim 11, further comprising a DC-DC converter that is connected between the fuel cell and the battery. 13. A power generation system comprising: a power outlet; a fuel cell that is configured to selectively provide power for the power outlet; a battery; a grid-supply-connector for receiving a grid supply power; an uninterruptable power supply, UPS, that has: a grid-input terminal, a power-output-terminal and a battery-connection-terminal, wherein: the grid-input terminal is connected to the grid-supply-connector, the power-output-terminal is connected to the power outlet; the battery-connection-terminal is connected to the battery; and the UPS is configured to provide power that it receives at the grid- input terminal and / or the battery-connection-terminal to the power-output- terminal; wherein the UPS is configured to provide power that it receives at the grid-input terminal to the battery-connection-terminal in order to charge the battery. 14. The power generation system of claim 13, further comprising: an inverter configured to convert a DC output voltage provided by the fuel cell into an inverter-AC-voltage, and wherein the inverter is configured to provide the inverter-AC voltage to the power outlet. 15. The power generation system of claim 13 or claim 14, wherein the fuel cell is configured to provide power to charge the battery. 16. A power generation system comprising: a power outlet; an inverter configured to convert a DC output voltage into an inverter-AC-voltage, and wherein the inverter is configured to provide the inverter-AC voltage to the power outlet; a battery; a grid-supply-connector for receiving a grid supply voltage; an uninterruptable power supply, UPS, that has: a grid-input terminal, a power-output-terminal and a battery-connection-terminal, wherein: the grid-input terminal is connected to the grid-supply-connector; the power-output-terminal is connected to the power outlet; and the battery-connection-terminal is connected to the battery; and a controller that is configured to: receive a grid-supply-characteristic-signal that represents a characteristic level of the grid supply voltage; provide an inverter-control-signal to the inverter based on the grid-supply-characteristic-signal, wherein the inverter-control-signal is for setting or limiting the inverter power output supplied. 17. The power generation system of claim 16, further comprising: a fuel cell configured to provide a DC output voltage; and wherein the inverter is configured to convert the DC output voltage provided by the fuel cell into the inverter-AC-voltage. 18. The power generation system of claim 16 or claim 17, further comprising: a recirculation-switch that is configured to selectively connect the power- output-terminal of the UPS to the grid-input terminal of the UPS. 19. The power generation system of claim 18, the controller is configured to operate the recirculation-switch based on the grid-supply-characteristic-signal. 20. The power generation system of claim 18 or claim 19, wherein the controller is configured to operate the recirculation-switch such that it connects the power-output-terminal to the grid-input terminal of the UPS. 21. The power generation system of any one of claims 18 to 20, further comprising: a grid-isolation-switch that is configured to selectively disconnect the grid-input terminal of the UPS from the grid-supply-connector. 22. The power generation system of claim 21, wherein the controller is configured to operate the grid-isolation-switch based on the grid-supply- characteristic-signal. 23. The power generation system of claim 21, wherein the controller is configured to operate the grid-isolation-switch such that it disconnects the grid-input terminal of the UPS from the grid-supply-connector if the grid- supply-characteristic-signal does not meet a grid-supply-quality threshold. 24. The power generation system of any one of claims 21 to 23, wherein the controller is configured to: set the grid-isolation-switch such that it disconnects the grid-input terminal of the UPS from the grid-supply-connector before it sets the recirculation-switch such that it connects the power-output-terminal of the UPS to the grid-input terminal of the UPS. 25. The power generation system of claim 24, wherein the controller is configured to: apply a minimum time delay between setting the grid-isolation-switch such that it disconnects the grid-input terminal of the UPS from the grid- supply-connector and setting the recirculation-switch such that it connects the power-output-terminal of the UPS to the grid-input terminal of the UPS. 26. The power generation system of any one of claims 18 to 25, wherein the recirculation-switch is configured to selectively connect a protected earth terminal of the power-output-terminal to a neutral terminal and optionally one or more localised earth rods, or similar earthing arrangements. 27. The power generation system of claim 26, wherein the protected earth terminal of the power-output-terminal is selectively connected to a protected earth terminal of the grid-input terminal. 28. An inverter circuit comprising: a DC-input-terminal and a reference-terminal, across which a DC voltage signal is provided when in use; a plurality of inverters, each inverter comprising: a first-inverter-input- terminal; and a second-inverter-input-terminal, wherein each of the plurality of inverters is configured to convert a DC voltage received across the first- inverter-input-terminal and the second-inverter-input-terminal in order to provide an AC voltage output; a plurality of diodes, one for each of the plurality of inverters; wherein: the first-inverter-input-terminal of each of the plurality of inverters is connected to the DC-input-terminal; the second-inverter-input-terminal of each of the plurality of inverters is connected to the reference-terminal through a respective one of the plurality of diodes such that current is inhibited from flowing from the reference- terminal to the second-inverter-input-terminal. 29. The inverter circuit of claim 28, further comprising: a plurality of capacitors, one for each of the plurality of inverters; wherein: each of the plurality of capacitors is connected between the first- inverter-input-terminal and the second-inverter-input-terminal of a respective one of the plurality of the inverters. 30. The inverter circuit of claim 28 or claim 29, further comprising: a plurality of first-inverter-input-ferrites, one for each of the plurality of inverters; a plurality of second-inverter-input-ferrites, one for each of the plurality of inverters; wherein: each of the plurality of first-inverter-input-ferrites is connected in series between the first-inverter-input-terminal of a respective one of the plurality of the inverters and the DC-input-terminal; and each of the plurality of second-inverter-input-ferrites is connected in series between the second-inverter-input-terminal of a respective one of the plurality of the inverters and the reference-terminal. 31. The inverter circuit of claim 28, further comprising: a plurality of first-inverter-input-ferrites, one for each of the plurality of inverters; a plurality of second-inverter-input-ferrites, one for each of the plurality of inverters; a plurality of DC-input-ferrites, one for each of the plurality of inverters; a plurality of reference-input-ferrites, one for each of the plurality of inverters; wherein, for each of the inverters: a respective one of the first-inverter-input-ferrites is connected in series between the first-inverter-input-terminal and a first node; a respective one of the DC-input-ferrites is connected in series between the first node and the DC-input-terminal; a respective one of the second-inverter-input-ferrites is connected in series between the second-inverter-input-terminal and a second node; a respective one of the reference-input-ferrites is connected in series between the second node and an anode of a respective one of the diodes; a cathode of the respective one of the diodes is connected to the reference-terminal; and a respective one of the capacitors is connected between the first node and the second node. 32. A circuit for a power generation system, wherein the circuit comprises: an earth-output-terminal and three live-output-terminals; a ground-terminal; an inverter that is configured to convert a DC voltage that is provided by fuel cell into an inverter-AC-voltage, wherein the inverter comprises an inverter-neutral-output-terminal and three inverter-live-output-terminals; and a galvanic-isolation-circuit, wherein: the galvanic-isolation-circuit comprises an isolation-transformer that includes: three primary windings, each connected between a respective one of the three inverter-live-output-terminals and the inverter- neutral-output-terminal; three secondary windings, each connected between a different pair of the three live-output-terminals; and the galvanic-isolation-circuit provides a connection between the earth-output-terminal and the ground-terminal; the galvanic-isolation-circuit includes an isolation-resistor and an isolation-capacitor that are connected in parallel with each other between the inverter-neutral-output-terminal and the ground-terminal. 33. The circuit of claim 32, wherein the isolation-resistor and the isolation- capacitor provide a high impedance connection to ground for the inverter. 34. The circuit of claim 32 or claim 33, wherein the values of the isolation- resistor and the isolation-capacitor are such that current to ground for a given operating voltage is below a current-threshold. 35. A power generation system comprising: a power outlet; a fuel cell that is configured to selectively provide power for the power outlet; a galvanic-isolation-circuit that is configured to: transfer power between the fuel cell and the power outlet (could be indirectly via the battery), and provide galvanic isolation between the fuel cell and the power outlet; a controller configured to: receive a resistance-signal that represents the resistance between a power-transfer-node and earth, wherein the power-transfer-node is a node in the power transfer path between, and including, the fuel cell and the isolation-circuit; and if the received resistance-signal is less than a resistance-threshold then perform one or more safety-operations. 36. The power generation system of claim 35, wherein the one or more safety-operations comprise: shutting down the fuel cell; ceasing supply of hydrogen fuel to the fuel cell; disconnecting the fuel cell from the galvanic-isolation-circuit; disconnecting the fuel cell from the power outlet; and isolating the power outlet such that it does not receive power from the power generation system. 37. The power generation system of claim 35 or claim 36, wherein: the power generation system comprises a grid-supply-connector for receiving a grid supply voltage; and the one or more safety-operations comprises isolating the grid-supply- connector such that it does not provide power to the power generation system. 38. The power generation system of any one of claims 35 to 37, wherein: the power generation system comprises an uninterruptable power supply, UPS; and the one or more safety-operations comprises disconnecting the UPS from the power outlet. 39. The power generation system of claim 35, wherein: wherein the one or more safety-operations comprise ceasing supply of hydrogen fuel to the fuel cell by closing a shut-off valve that is in a fuel flow path between a hydrogen supply and the fuel cell. 40. The power generation system of claim 39, the shut-off valve is a normally closed valve. 41. The power generation system of any one of claims 35 to 40, wherein the controller is configured to: if the received resistance-signal returns to being greater than a reconnect-resistance-threshold, after being less than the resistance-threshold, then perform one or more reconnection-operations. 42. The power generation system of claim 41, wherein the one or more reconnection-operations comprise: restarting the fuel cell; recommencing supply of hydrogen fuel to the fuel cell; reconnecting the fuel cell to the galvanic-isolation-circuit; reconnecting the fuel cell to the power outlet; and reconnecting the power outlet such that it does receive power from the power generation system. 43. The power generation system of claim 41, wherein: the power generation system comprises a grid-supply-connector for receiving a grid supply voltage; and the one or more reconnection-operations comprises reconnecting the grid-supply-connector such that it does provide power to the power generation system. 44. The power generation system of claim 41, wherein: the power generation system comprises an uninterruptable power supply, UPS; and the one or more reconnection-operations comprises reconnecting the UPS to the power outlet. 45. A power generation system comprising: a power outlet; a fuel cell that is configured to selectively provide power for the power outlet; a battery that is configured to selectively provide power for the power outlet; a grid-supply-connector for receiving a grid supply voltage; an uninterruptable power supply, UPS, that has: a grid-input terminal, a power-output-terminal and a battery-connection-terminal, wherein: the grid-input terminal is connected to the grid-supply-connector, the power-output-terminal is connected to the power outlet; and the battery-connection-terminal is connected to the battery; and a controller configured to: perform one or more safety-operations in response to receiving an alarm-trigger-signal. 46. The power generation system of claim 45, wherein the controller is configured to, as a safety-operation: provide a fuel-cell-power-control-signal for reducing the power that is provided by the fuel cell. 47. The power generation system of claim 46, wherein the controller is configured to provide a fuel-cell-power-control-signal for reducing the power that is provided by the fuel cell down to zero. 48. The power generation system of claim 46 or claim 47, wherein the controller is configured to provide a fuel-cell-power-control-signal for gradually reducing the power that is provided by the fuel cell. 49. The power generation system of any one of claims 45 to 48, wherein: the power generation system comprises a shut-off valve for ceasing supply of hydrogen fuel to the fuel cell; and the controller is configured to, as a safety-operation: cause the shut-off valve to cease supply of hydrogen fuel to the fuel cell. 50. The power generation system of claim 49, wherein the shut-off valve is a normally closed valve. 51. The power generation system of any of claims 45 to 50, wherein: the power generation system comprises a galvanic-isolation-circuit that is configured to: transfer power between the fuel cell and the power outlet, and provide galvanic isolation between the fuel cell and the power outlet; and the controller is configured to, as a safety-operation: disconnect the fuel cell from the galvanic-isolation-circuit. 52. The power generation system of any of claims 45 to 51, wherein: the power generation system comprises a fuel-cell-isolation-switch for selectively connecting / disconnecting the fuel cell to / from the power outlet; and the controller is configured to, as a safety-operation: operate the fuel-cell-isolation-switch in order to disconnect the fuel cell from the power outlet. 53. The power generation system of any of claims 45 to 52, wherein: the power generation system comprises a power-outlet-isolation-switch for selectively connecting / disconnecting the power outlet from the UPS and / or the fuel cell; and the controller is configured to, as a safety-operation: operate the power-outlet-isolation-switch such that the power outlet does not receive power from the power generation system. 54. The power generation system of any of claims 45 to 53, wherein: the power generation system comprises a grid-isolation-switch for selectively connecting / disconnecting the grid-supply-connector to / from the UPS; and the controller is configured to, as a safety-operation: operate the grid-isolation-switch such that the UPS does not receive power from the grid-supply-connector. 55. The power generation system of any of claims 45 to 54, wherein the controller comprises one or more relays that are configured to perform one or more of the safety-operations. 56. The power generation system of claim 55, wherein the one or more relays are hard-wired to one or more actuators that are configured to implement safety-operations. 57. The power generation system of claim 55, wherein the one or more actuators comprise: a shut-off valve; a fuel-cell-isolation-switch; a power-outlet-isolation-switch; and a grid-isolation-switch. 58. The power generation system of any one of claims 45 to 57, further comprising a user interface that is operable by a user to provide the alarm- trigger-signal to the controller. 59. The power generation system of claim 58, wherein: the user interface comprises an emergency stop button that is remote from the power generation system; and / or the user interface comprises an emergency stop button that is local to the power generation system; and / or the user interface is configured to wirelessly provide the alarm-trigger- signal to the controller. 60. The power generation system of claim 58 or claim 59, wherein: the power generation system comprises a shipping container, which houses the fuel cell, the battery and the UPS; and the user interface comprises one or both of: an emergency stop button inside the shipping container; and an emergency stop button outside the shipping container. 61. The power generation system of any of claims 45 to 60, further comprising a sensor that is configured to provide the alarm-trigger-signal. 62. The power generation system of claim 61, wherein the sensor comprises one or more of: a smoke sensor associated with the power generation system; a heat sensor associated with the power generation system; a gas sensor associated with the power generation system; and an airflow sensor for sensing airflow in a fuel cell compartment of the power generation system. 63. The power generation system of any of claims 45 to 62, wherein the controller is configured to: receive one or more system-parameters that represent one or more operating parameters of the power generation system; and generate the alarm-trigger-signal based on the one or more system- parameters. 64. The power generation system of claim 63, wherein the one or more operating parameters of the power generation system comprise one or more fuel-cell-parameters that represent one or more operating parameters of the fuel cell. 65. A power generation system comprising: a container having an interior volume; a fuel cell compartment, which is a portion of the interior volume that is defined by one or more fuel-cell-partitions in the container; a fuel cell located within the fuel cell compartment; a battery compartment, which is a portion of the interior volume that is defined by one or more battery-partitions; a battery located within the battery compartment; a control compartment, which is a portion of the interior volume that is: separated from the fuel cell compartment by the one or more fuel- cell-partitions; separated from the battery compartment by the one or more battery-partitions; an outflow vent; and a fan configured to reduce the air pressure in the fuel cell compartment such that air is drawn through the battery compartment and the fuel cell compartment and exits the container through the outflow vent. 66. The power generation system of claim 65, wherein the outflow vent is in an external wall of the container. 67. The power generation system of claim 66, wherein the outflow vent is in an external wall of the container that defines a wall of the fuel cell compartment. 68. The power generation system of any one of claims 65 to 67, further comprising: an inflow vent in an external wall of the container; and wherein: the fan is configured to draw air into the battery compartment and the fuel cell compartment from outside the container through the inflow vent. 69. The power generation system of any one of claims 65 to 68, wherein the one or more battery-partitions comprises a raised-floor-battery-partition that is generally parallel with, and spaced apart from, a bottom wall of the container, such that the battery compartment is defined between the raised- floor-battery-partition and the bottom wall of the container. 70. The power generation system of any one of claims 65 to 69, wherein the inflow vent is in an external wall that defines the battery compartment. 71. The power generation system of any one of claims 65 to 70, wherein the one or more fuel-cell-partitions comprises an internal-wall-partition that is generally parallel with, and spaced apart from, a side wall of the container, such that the fuel cell compartment is defined between the internal-wall- partition and the side wall of the container. 72. The power generation system of any one of claims 65 to 71, wherein the outflow vent is in an external wall that defines the fuel cell compartment. 73. The power generation system of claim 72, wherein the outflow vent is in an upper region of the external wall, optionally proximal to the ceiling. 74. The power generation system of any one of claims 65 to 73, wherein the fan is configured to blow air out of the container through the outflow vent, thereby reducing the air pressure in the fuel cell compartment and the battery compartment. 75. The power generation system of claim 65, wherein: the one or more battery-partitions comprises a raised-floor-battery- partition that is generally parallel with, and spaced apart from, a bottom wall of the container, such that the battery compartment is defined between the raised-floor-battery-partition and the bottom wall of the container; the one or more fuel-cell-partitions comprises an internal-wall-partition that is generally parallel with, and spaced apart from, a first side wall of the container, such that the fuel cell compartment is defined between the internal- wall-partition and the side wall of the container; the container comprises a ceiling; and the internal-wall-partition extends between the ceiling and the raised- floor-battery-partition. 76. The power generation system of claim 75, wherein the raised-floor- battery-partition extends between a second side wall, that is opposite the first side wall, and the internal-wall-partition. 77. The power generation system of any one of claims 65 to 76, wherein the control compartment houses one or more of: a UPS; a controller; one or more relays; one or more switches; a galvanic-isolation-circuit; an inverter; a smoke sensor / alarm; a heat sensor / alarm; a gas sensor / alarm; and an oxygen monitoring system. 78. The power generation system of any one of claims 65 to 77, further comprising: an internal-partition that partially defines the fuel cell compartment and also partially defines the battery compartment; and an internal vent in the internal-partition such that air can flow between the battery compartment and the fuel cell compartment. 79. The power generation system of claim 78, wherein the internal-partition is in the same plane as the raised-floor-battery-partition. 80. A power generation system comprising: a container; a fuel cell within the container; a hydrogen flow control valve that is in a conduit between a hydrogen supply that is outside the container, and the fuel cell; and an inert gas control system that is configured to operate the hydrogen flow control valve. 81. The power generation system of claim 80, wherein the hydrogen flow control valve is outside the container. 82. The power generation system of claim 80 or 81, wherein the hydrogen flow control valve is a normally closed valve. 83. A power generation system comprising: a container; a control compartment, which is a portion of an interior volume of the container, a fuel cell compartment, which is within the footprint of the container, and is separated from the control compartment by one or more gas-tight fuel- cell-partitions; a fuel cell located within the fuel cell compartment; a battery compartment, which is a portion of the interior volume of the container that is defined by one or more battery-partitions; a battery located within the battery compartment; and a fan configured to draw air into the fuel cell compartment from the battery compartment. 84. The power generation system of claim 83, wherein the fuel cell compartment is open to atmosphere. 85. The power generation system of claim 83 or claim 84, wherein the fan is configured reduce the pressure in the battery compartment. 86. The power generation system of any one of claims 83 to 85, further comprising an internal-partition that partially defines the fuel cell compartment and also partially defines the battery compartment; and wherein the fan is located in the internal-partition. 87. The power generation system of claim 86, wherein the internal-partition is in the same plane as one of the gas-tight fuel-cell-partitions. 88. The power generation system of any one of claims 83 to 87, further comprising an outflow vent in an external wall of the container that defines the fuel cell compartment. 89. The power generation system of claim 88, wherein the outflow vent is at an uppermost region of the fuel cell compartment. 90. The power generation system of claim 89, further comprising a ceiling within the fuel cell compartment that is angled such that it defines a surface that extends upwards towards the outflow vent. 91. The power generation system of any one of claims 83 to 90, further comprising: a hydrogen flow control valve that is in a conduit between a hydrogen supply and the fuel cell; and an inert gas control system that is configured to operate the hydrogen flow control valve. 92. The power generation system of claim 91, wherein the hydrogen flow control valve is within the footprint of the container. 93. The power generation system of claim 91 or claim 92, wherein the hydrogen flow control valve is a normally closed valve. 94. The power generation system of any one of claims 83 to 93, further comprising: an inflow vent in an external wall of the container; and wherein: the fan is configured to draw air into the battery compartment from outside the container through the inflow vent. 95. The power generation system of any one of claims 83 to 94, wherein the one or more battery-partitions comprises a raised-floor-battery-partition that is generally parallel with, and spaced apart from, a bottom wall of the container, such that the battery compartment is defined between the raised- floor-battery-partition and a bottom wall of the container. 96. The power generation system of claim 95, wherein the inflow vent is in an external wall that defines the battery compartment. 97. The power generation system of any one of claims 83 to 96, wherein the one or more gas-tight fuel-cell-partitions comprises a gas-tight internal-wall- partition that is generally parallel with, and spaced apart from, a second side wall of the container, such that the control compartment is defined between the internal-wall-partition and the second side wall of the container. 98. The power generation system of claim 83, wherein: the one or more battery-partitions comprises a raised-floor-battery- partition that is generally parallel with, and spaced apart from, a bottom wall of the container, such that the battery compartment is defined between the raised-floor-battery-partition and the bottom wall of the container; the one or more gas-tight fuel-cell-partitions comprises a gas-tight internal-wall-partition that is generally parallel with, and spaced apart from, a second side wall of the container, such that the control compartment is defined between the gas-tight internal-wall-partition and the second side wall of the container; the container comprises a ceiling; and the gas-tight internal-wall-partition extends between the ceiling and the raised-floor-battery-partition. 99. The power generation system of claim 98, wherein the raised-floor- battery-partition extends between the second side wall and the internal-wall- partition. 100. The power generation system of any one of claims 83 to 99, wherein the control compartment houses one or more of: a UPS; a controller; one or more relays; one or more switches; a galvanic-isolation-circuit; an inverter; a smoke sensor / alarm; a heat sensor / alarm; a gas sensor / alarm; and an oxygen monitoring system. 101. A power generation system comprising: a container having an interior volume; a fuel cell compartment, which is a portion of the interior volume that is defined by one or more fuel-cell-partitions in the container; a fuel cell located within the fuel cell compartment; a battery compartment, which is a portion of the interior volume that is defined by one or more battery-partitions; a battery located within the battery compartment; a control compartment, which is a portion of the interior volume that is: separated from the fuel cell compartment by the one or more fuel- cell-partitions; and separated from the battery compartment by the one or more battery-partitions; and one or more rupture panels in an exterior wall or ceiling of the container. 102. The power generation system of claim 101, wherein the rupture panels are configured to be removable from respective frames in the exterior wall or ceiling of the container in response to a rapid increase in air pressure within the container. 103. The power generation system of claim 101 or claim 102, wherein at least one of the rupture panels is located in an exterior wall or ceiling of the container that defines the fuel cell compartment. 104. The power generation system of any one of claims 101 to 103, wherein at least one of the rupture panels is located in an exterior wall or ceiling of the container that defines the control compartment. 105. The power generation system of any one of claims 101 to 104, wherein at least one of the rupture panels is located in the ceiling of the container. 106. The power generation system of any one of claims 101 to 105, wherein at least one of the rupture panels has one edge that is more securely affixed to the container than other edges of the rupture panel. 107. A power generation system comprising: a container; a fuel cell located within the container; a fuel cell cooling loop for removing heat from the fuel cell; and a heat exchanger for transferring heat from the fuel cell cooling loop such that it can be used to service a local application that requires heat. 108. The power generation system of claim 107, wherein the local application comprises one or more of: providing a hot water supply; providing space heating; and providing heating for one or more processes. 109. The power generation system of claim 107 or claim 108, further comprising an additional cooling loop for receiving heat from the fuel cell cooling loop through the heat exchanger, and wherein the additional cooling loop is configured to selectively heat water in a water tank such that it can be provided as a hot water supply. 110. The power generation system of claim 109, further comprising one or more valves in the additional cooling loop that are operable to selectively direct fluid in the additional cooling loop to heat the water in the water tank. 111. The power generation system of claim 109 or claim 110, further comprising a heat removal component that selectively transfers heat from the fluid within the additional cooling loop to atmosphere. 112. The power generation system of claim 111, wherein the heat removal component comprises a radiator and a fan. 113. The power generation system of claim 112, wherein the heat removal component is configured to be automatically activated when the temperature of the fluid in the additional cooling loop exceeds a predetermined setpoint. |
Electrical Systems Figure 10 shows an example of a power generation system 1000. Features of Figure 10 that have been described with reference to an earlier drawing (especially Figures 2 and 6) have been given corresponding reference numbers in the 1000 series. The power generation system 1000 includes a power outlet 1004, a fuel cell 1002 and a UPS 1016. The fuel cell 1002 is configured to selectively provide power for the power outlet 1004 in the same way as described above. For instance, the fuel cell 1002 can directly provide power to the power outlet 1004 or it can indirectly provide power to the power outlet 1004 by charging a battery 1003, which in turn provides power to the power outlet 1004. The power generation system 1000 also includes a galvanic-isolation-circuit 1057 that can transfer power between the fuel cell 1002 and the power outlet 1004. As above, this transfer of power can be indirect via a battery 1003 in some examples. The galvanic-isolation-circuit 1057 can also provide galvanic isolation between the fuel cell 1002 and the power outlet 1004. As discussed above, this galvanic isolation is required for fuel cell operation and can provide significant equipment and reliability advantages along with safety advantages when combined with a ground fault monitoring system. In Figure 2, the functionality of the galvanic-isolation-circuit 1057 is provided by a multi transformer galvanic isolation block 258 (which is shown in more detail in Figure 9). In addition, the galvanic-isolation-circuit 1057, as it is shown in Figure 10, provides the functionality of the inverter array 214 of Figure 2. For this reason, the galvanic-isolation-circuit 1057 in Figure 10 can be considered as providing an AC link between the fuel cell 1002 and the power outlet 1004. In Figure 6, the functionality of the galvanic-isolation-circuit 1057 is provided by a DC-DC galvanic isolated coupling array 631. The galvanic-isolation-circuit 1057 in Figure 10 can therefore also, or instead, be considered as providing a DC link between the fuel cell 1002 and the battery 1003. Returning to Figure 10, the power generation circuit 1000 includes a controller 1012 that receives a resistance-signal 1059 that represents the resistance between a power-transfer-node 1062 and earth 1063. The power-transfer- node 1062 is a node in the power transfer path (in this example the DC power transfer path) between, and including, the fuel cell 1002 and the isolation- circuit 1057. In this example the power-transfer-node 1062 is between the fuel cell 1002 and a common rail galvanic isolated DC circuit 1064 (which can be implemented as the circuit of Figure 8 in some examples). In Figure 10, the resistance-signal 1059 is provided by a ground fault relay or ohmmeter 1061 that is connected between the power-transfer-node 1062 and earth 1063. In this example, a ground fault monitor 1060 is connected between the ohmmeter 1061 and the controller 1012 in order to perform any optional processing on the resistance-signal 1059 that is provided by the ohmmeter 1062 before it is provided to the controller 1012. If the received resistance-signal 1059 is less than a value where currents could flow to ground that would be injurious to human health, typically a resistance- threshold, then the controller 1012 performs one or more safety-operations. Non-limiting examples of suitable resistance-thresholds include a range of 5,000 to 275,000 ohms, such as 5,000 ohms, 10,000 ohms, 50,000 ohms, 100,000 ohms, 275,000 ohms, or 300,000 ohms. It has been found that if the resistance between the power-transfer-node 1062 and earth 1063 drops below a certain level then there is most likely an undesirable path to ground. This should not be the case if the power generation system 1000 is working correctly because this part of the system (the power transfer path between, and including, the fuel cell 1002 and the isolation-circuit 1057) should be floating. By monitoring the resistance-signal 1059 in this way, the equipment of the power generation system 1000 can be protected, and personnel can be protected from electrical shock. The one or more safety-operations can include: x shutting down the fuel cell and / or isolating the inverters. This safety- operation can be performed by the fuel cell controller 1065 in Figure 10, which can be considered as part of the controller, even though it is shown separately from the PLC controller 1012 in Figure 10. x ceasing supply of hydrogen fuel to the fuel cell 1002. This safety- operation can include the controller (in this example the PLC controller 1012) closing a shut-off valve 1066 that is in a fuel flow path between a hydrogen supply 1006 and the fuel cell 1002. This safety-operation can also be implemented by a relay 1067 (which can be considered as providing part of the functionality of the controller more generally) closing a shut-off valve 1066. The relay 1067 will be described in more detail below. The shut-off valve 1066 can advantageously be implemented as a normally closed valve. This provides a safety advantage in that the fuel supply is cut off if the shut-off valve 1066 is unpowered. x disconnecting the fuel cell 1002 from the galvanic-isolation-circuit 1057 and / or from the power outlet 1004. This safety-operation can include the controller (either the PLC controller 1012 or the relay 1067) opening one or more fuel-cell-isolation-switches (not shown) within the galvanic- isolation-circuit 1057. x isolating the power outlet 1004 such that it does not receive power from the power generation system 1000. This safety-operation can include the controller (either the PLC controller 1012 or the relay 1067) opening a power-outlet-isolation-switch 1068 for disconnecting the power outlet 1004 from the UPS 1016 and / or the fuel cell 1002. x disconnecting the UPS 1016 from the power outlet 1016, which again can be implemented by the controller opening the power-outlet- isolation-switch 1068 for the embodiment of Figure 10. x increasing the speed of a fan (such as the fan 1172, 172 that will be described below with reference to Figures 11 and 1) that causes air to be drawn through a fuel cell compartment 1108 and exit the container / power generation system through an outflow vent. In the example of Figure 10, the power generation system 1000 also includes a grid-supply-connector 1011 for receiving a grid supply voltage in the same way as described above. In which case, the one or more safety-operations can include isolating the grid-supply-connector 1011 such that it does not provide power to the power generation system 1000. This safety-operation can include the controller (either the PLC controller 1012 or the relay 1067) opening a grid- isolation-switch 1029 for disconnecting the grid-supply-connector 1011 from the UPS 1016. If the received resistance-signal 1059 returns to being greater than a reconnect-resistance-threshold, after being less than the resistance-threshold, then the controller can perform one or more reconnection-operations. It will be appreciated that the reconnect-resistance-threshold can be greater than the resistance-threshold in order to provide some hysteresis in its operation. As will be discussed below, performing one or more reconnection-operations can enable the controller to put the power generation system back into a full working mode of operation after the fault that caused the resistance to drop has been removed. The one or more reconnection-operations can include: x restarting the fuel cell 1002. x recommencing supply of hydrogen fuel to the fuel cell 1002, for instance by opening the shut-off valve 1066. x reconnecting the fuel cell 1002 to the galvanic-isolation-circuit 1067, for instance by closing one or more fuel-cell-isolation-switches (not shown) within the galvanic-isolation-circuit 1057. x reconnecting the fuel cell 1002 to the power outlet 1004, for instance by closing the fuel-cell-isolation-switch within the galvanic-isolation-circuit 1057; x reconnecting the power outlet 1004 such that it does receive power from the power generation system 1000, for instance by closing the power- outlet-isolation-switch 1068. x reconnecting the UPS 1016 to the power outlet 1004, for instance by closing the power-outlet-isolation-switch 1068. x reconnecting the grid-supply-connector 1011 such that it does provide power to the power generation system 1000, for instance by closing the grid-isolation-switch 1029. In this way, AC site loads can be provided by MCCB (moulded case circuit breaker) over-current protection and neutral earth bonding to prevent electric shock. The fuel cell electrical connection is a floating non-grounded type where insulation to ground can be constantly monitored for a fault. A ground fault in this circuit can cause the controller to perform a controlled shutdown of the fuel cell and to remove the load to protect equipment and personnel from electrical shock. This can include neutral earth switching, as shown schematically in Figure 10 with reference 1071, where a local neutral earth is established at the point of switching from grid to island power. This corresponds to the functionality that is described above with reference to Figure 7. A controlled shutdown can include the controller sending a signal to shutdown the fuel cell, while the hydrogen fuel supply and fuel cell power supply is maintained. This can be in contrast to an emergency shutdown where the power output and power supply of the fuel cell is isolated immediately, and the hydrogen fuel supply is isolated at an external valve. This can be damaging to the fuel cell, and so may only be implemented as part of a potentially very serious safety-operation. We will now describe an aspect of the power generation system 1000 of Figure 10 that relates to receiving and responding to an alarm-trigger-signal more generally (the resistance-signal that is described above is one example of an alarm-trigger-signal) such that equipment and personnel can be protected. One or more of the following features of the power generation system 1000 can be particularly for this aspect: the power outlet 1004; the fuel cell 1002 that is configured to selectively provide power for the power outlet 1004; the battery 1003 that is configured to selectively provide power for the power outlet 1004; the grid-supply-connector 1011 for receiving a grid supply voltage; and the UPS 1016. In the same way that is described above, the UPS 1016 has: a grid-input terminal 1024 connected to the grid-supply-connector 1011; a power-output-terminal 1025 connected to the power outlet 1004; and a battery-connection-terminal 1026 connected to the battery 1003. Also, at least the fuel cell 1002, the battery 1003 and the UPS 1016 are housed within a shipping container 1001. The controller of Figure 10 (which can be the PLC 1012, the fuel cell controller 1065 and / or the relay 1067) is configured to perform one or more safety- operations in response to receiving an alarm-trigger-signal. Examples of safety-operations that can be performed by the controller include: x providing a fuel-cell-power-control-signal for reducing the power that is provided by the fuel cell 1002 and shutting down the fuel cell in a controlled way. x causing the shut-off valve 1066 to cease supply of hydrogen fuel to the fuel cell and within the container 1002. x disconnecting the fuel cell 1002 from the galvanic-isolation-circuit 1057, which can be achieved by operating a fuel-cell-isolation-switch (which may be inside the block that is labelled as AC or DC link in Figure 10). x disconnecting the fuel cell 1002 from the power outlet 1004, which can be achieved by operating a fuel-cell-isolation-switch in order to disconnect the fuel cell 1002 from the power outlet 1004. x disconnecting the power outlet 1004 from the UPS 1016 and / or the fuel cell 1002, which can be achieved by operating a power-outlet-isolation- switch 1068 such that the power outlet 1004 does not receive power from the power generation system 1000. x disconnecting the grid-supply-connector 1011 from the UPS 1016, which can be achieved by operating a grid-isolation-switch 1029 such that the UPS 1016 does not receive power from the grid-supply-connector 1011. As indicated above, the controller can include one or more relays 1067 that are configured to perform one or more of the safety-operations. The one or more relays 1067 can be considered as electrical safety relays, and can be hard- wired to one or more actuators that are configured to implement safety- operations. In the example of Figure 10, the one or more actuators include: the shut-off valve 1066; the fuel-cell-isolation-switch (not shown); the power- outlet-isolation-switch 1068; and the grid-isolation-switch 1029. The one or more relays 1067 can be used to implement safety-critical safety-operations, including those that are especially important for maintaining the safety of personnel. The power generation system 1000 of Figure 10 includes a manually operable user interface, which a user can operate to provide the alarm-trigger-signal to the controller. The user interface of Figure 10 includes an emergency stop button 1069 that is local to the power generation system 1000 (for instance inside a shipping container 1001). The user interface of Figure 10 also includes an emergency stop button 1070 that is remote from the power generation system 1000 (for instance outside the shipping container 1001). As a further example, the user interface can wirelessly provide the alarm-trigger-signal to the controller, for instance in response to a user activating a remote emergency shut down button 1098. Such a remote emergency shut down button 1098 can be provided on a computing device, including a portable computing device such as a smart phone, a tablet computer or a laptop computer. As a further example, a sensor can provide the alarm-trigger-signal. Optionally, the sensor can provide the alarm-trigger-signal to the one or more relays 1067, especially where the sensors are providing safety critical information. Examples of suitable sensors include: a smoke sensor / alarm associated with the power generation system 1000 (optionally inside the shipping container 1001); a heat sensor / alarm associated with the power generation system 1000 (optionally inside the shipping container 1001); and a gas sensor / alarm associated with the power generation system 1000 (optionally inside the shipping container 1001). As an additional example, an airflow sensor for sensing airflow in the fuel cell compartment or battery compartment of the power generation system. The airflow sensor can generate an alarm-trigger-signal if the airflow is considered potentially insufficient to reliably remove any leaked hydrogen. The airflow sensor can directly measure airflow, or it can measure air pressure which (due to a differential with ambient air pressure outside the container) can be another way of representing airflow. As a further still example, the airflow sensor can measure an operational parameter of a fan that is used to create the airflow through the fuel cell compartment, as will be discussed in more detail below. In some examples, the controller (in this example the PLC controller 1012) receives one or more system-parameters (example of which are the fuel-cell- parameters that are described above) that represent one or more operating parameters of the power generation system 1000. The controller can then generate the alarm-trigger-signal based on the one or more system- parameters. In this way, an electrical safety system can be implemented as a three-way protection system: x Manually activated via emergency stop buttons 1069, 1070, 1098; x Automatically activated hardwired supervisory relays with signals from: o Gas detection alarms; and o Smoke and heat detectors; and x Automatically activated via programmable logic controller (PLC) 1012 and software This can result in immediate shutdown of the system in an emergency. An emergency stop button press or critical fire or gas detection can result in: x Disconnection of the grid supply; x Disconnection of the site supply; x Shutting down of the fuel cell; and x All gas shutdown emergency procedures that are disclosed herein. Also, system parameters can be monitored by the PLC 1012 that result in controlled stopping of the power generation system 1000 when parameters exceed set limits to protect personnel and equipment.
Gas Safety Systems Figure 11 shows a cross-sectional view of another example of a power generation system 1100. Features of Figure 11 that have been described with reference to an earlier drawing have been given corresponding reference numbers in the 1100 series. The power generation system 1100 of Figure 11 will be used to describe aspects of various gas safety systems. The power generation system 1100 includes a container 1101, in this example a shipping container 1101, which has an interior volume. The interior volume is sub-divided into three compartments: i) a fuel cell compartment 1108; ii) a battery compartment 1178 (also shown in Figure 1 with reference 178); and iii) a control compartment 1177 (also shown in Figure 1 with reference 177). A fuel cell 1102 is located within the fuel cell compartment 1108. The fuel cell compartment 1108 is a portion of the interior volume of the container 1101 that is defined by one or more fuel-cell-partitions in the container. In this example the one or more fuel-cell-partitions includes an internal-wall-partition 1107 that is generally parallel with, and spaced apart from, a side wall 1179 of the container 1101. In this way, the fuel cell compartment 1108 is a plenum that is defined between the internal-wall-partition 1107 and the side wall 1179 of the container 1101. A battery 1103 (in this example a battery array) is located within the battery compartment 1178. The battery compartment 1178 is a portion of the interior volume of the container 1101 that is defined by one or more battery-partitions. In this example the one or more battery-partitions includes a raised-floor- battery-partition 1176 that is generally parallel with, and spaced apart from, a bottom wall 1180 of the container 1101. In this way, the battery compartment 1178 is a plenum that is defined between the raised-floor-battery-partition 1176 and the bottom wall 1180 (floor) of the container 1101. (The raised- floor-battery-partition is also shown in Figure 1 with reference 176.) Figure 11 also shows an internal-partition 1175 that partially defines the fuel cell compartment 1108 and also partially defines the battery compartment 1178. The internal-partition 1175 is in the same plane as the raised-floor- battery-partition 1176. The raised-floor-battery-partition 1176 extends from a side wall of the container 1101 to an edge where it meets the internal-wall- partition 1107. The internal-wall-partition 1107 extends from the ceiling of the container 1101 to an edge where it meets the raised-floor-battery-partition 1176. The raised-floor-battery-partition 1176 is in a plane that is perpendicular to the internal-wall-partition 1107. The edge where the raised-floor-battery- partition 1176 and the internal-wall-partition 1107 meet is in an axis that is spaced apart from the parallel external walls of the container 1101. The internal-partition 1175 extends from the edge where the raised-floor-battery- partition 1176 and the internal-wall-partition 1107 meet to an external wall 1179 of the container 1101. In Figure 11 there is an internal vent in the internal-partition 1175 such that air can flow freely between the battery compartment 1178 and the fuel cell compartment 1108. The control compartment is a portion of the interior volume of the container 1101 that is: separated from the fuel cell compartment 1108 by the one or more fuel-cell-partitions 1107; and separated from the battery compartment 1178 by the one or more battery-partitions 1176. The control compartment 1177 houses one or more of: a UPS 1116; a controller (which can be implemented as a PLC 1112 and / or one or more relays 1167); one or more switches, a galvanic-isolation-circuit (not shown in Figure 11, but described extensively above); an inverter (not shown in Figure 11, but described extensively above); a smoke sensor / alarm; a heat sensor / alarm; a gas sensor / alarm; an oxygen monitoring system; and any other features of other examples of power generation systems disclosed herein. The control compartment 1177 can include potential sources of ignition that should be kept away from any potential hydrogen leaks for safety reasons. The power generation system 1100 of Figure 11 includes a fan 1172 that reduces the air pressure in the fuel cell compartment 1108 such that air is drawn through the battery compartment 1178 and the fuel cell compartment 1108 and exits the container through an outflow vent. This advantageously vents any leaked hydrogen to atmosphere through the outflow vent, and also provides cooling for the batteries in the battery compartment 1178. The outflow vent is not visible in Figure 11, although Figure 1 shows how the fan 172 is adjacent to an external wall of the container 101 (the back wall in Figure 1). It will be appreciated that there is an opening (outflow vent) in the external wall of the container 101 such that the fan 172 moves air from within the fuel cell compartment 108 to the outside of the container 101 through the opening, such that the air pressure in the fuel cell compartment 108 is reduce to below ambient air pressure. In the example of Figure 1 and 11, the outflow vent is in an external wall of the container 101, 1101 that also defines a wall of the fuel cell compartment 108, 1108. In this way the fan 172, 1172 can blow air out of the container 101, 1101 through the outflow vent, thereby reducing the air pressure in the fuel cell compartment 108, 1108 and the battery compartment 1178. Returning to Figure 11, the power generation system 1100 in this example also includes an inflow vent 1174 in an external wall of the container (in Figure 11 in the left wall of the container 1101). The fan 1172 draws air into the battery compartment 1178 and the fuel cell compartment 1108 from outside the container 1101 through the inflow vent 1174. In Figure 11, the inflow vent 1174 is in an external wall of the container 1101 that also defines the battery compartment 1178. The inflow vent 1174 is at an opposite end of the container 1101 to the fuel cell compartment (and the internal vent in the internal- partition 1175) such that air that is drawn into the battery cell compartment 1178 through the inflow vent 1174 has to travel the length of the battery compartment 1178 before exiting the battery compartment 1178 through the internal vent. As shown schematically in Figure 11 by various airflow arrows, the raised-floor- battery-partition 1176 does not need to provide a strictly gas-tight barrier between the battery compartment 1187 and the control compartment 1177. Similarly, the internal-wall-partition 1107 does not need to provide a gas-tight barrier between the fuel cell compartment 1108 and the control compartment 1177. The raised-floor-battery-partition 1176 should be sufficiently gas-tight such that the fan 1175 can maintain a sufficient air pressure differential between the battery compartment 1178 and the control compartment 1177, so that sufficient air flows over the battery 1103 for cooling purposes. Similarly, the internal-wall-partition 1107 should be sufficiently gas-tight such that the fan 1175 can maintain a sufficient air pressure differential between the fuel cell compartment 1108 and the control compartment 1177, to ensure that any leaked hydrogen from the fuel cell 1102 does not move into the control compartment 1177, and also so there is sufficient air flow through the fuel cell compartment 1108 to promptly remove any leaked hydrogen. The outflow vent in this example is in an upper region of an external wall that defines a wall of the fuel cell compartment 1108, and optionally proximal to the ceiling of the container 1101, which assist with the removal of any leaked hydrogen because it is less dense than air and therefore will rise to the top of the fuel cell compartment 1108. In this way, the fuel cell 1102 and the battery 1103 are positioned in a negative pressure gas safe zone (negative with respect to ambient atmosphere and the control compartment 1177), where an airflow path is carefully managed through strategically placed and sized external outflow vents, ensuring that any accidental hydrogen release by the fuel cell 1002 or battery 1003 is vented safely to atmosphere without encountering any source of ignition along its path. Any such potential sources of ignition can be present in the control compartment 1177. In this example, the fan 1172 can be implemented as a single ATEX fan to create the airflow, which is monitored continuously such that any loss of power causes the fuel cell 1102 to safely shutdown (as described above with reference to an alarm-trigger-signal that is provided by an airflow sensor). Another aspect of the power generation system 1100 that is illustrated in Figure relates to the positioning and operation of a hydrogen flow control valve 1166 (which may or may not be the same as the shut-off valve that is described above). As described above, the fuel cell 1102 is located within the container 1101. Also, a hydrogen supply 1106 is located outside the container 1101. The hydrogen flow control valve 1166 is also outside the container 1101, and is in a conduit between the hydrogen supply 1106 and the fuel cell 1102. In this example the hydrogen flow control valve 1166 is located in a high-pressure hydrogen panel that is affixed to an outer surface of the container 1101. The hydrogen flow control valve 1166 can be used to reduce the pressure of high- pressure hydrogen from the hydrogen supply 1106 before it is provided into the fuel cell 1102. The power generation system 1100 also includes an inert gas control system 1181 that is configured to operate the hydrogen flow control valve 1166. The hydrogen flow control valve 1166 (or valves if there is more than one) are triggered using an inert gas such that no source of ignition within the high- pressure hydrogen panel exists. In this way a high-pressure hydrogen supply is connected externally and the hydrogen is reduced in pressure before entering the container 1101, therefore reducing the risk of an explosive atmosphere developing within the container 1101. The system of Figure 11 further includes an external series of solenoid valves (not shown) that are configured to operate the inert gas control system 1181 based on control signals received from a controller (such as the PLC 1112) or other safety / control systems. This can advantageously enable an automated electronically triggered gas shutoff to be performed, without a risk of any sources of ignition in the vicinity of any hydrogen (especially high-pressure hydrogen). Beneficially, in this example the hydrogen flow control valve 1166 is a normally closed valve. In this way, the valves are normally closed in a de-energised state such that the removal of all power in an emergency or fault situation will eliminate any source of ignition and the gas supply. Figure 12a shows a longitudinal cross-sectional view of another example of a power generation system 1200. Figure 12b shows a lateral cross-sectional view of the power generation system 1200, through the fuel cell compartment 1208. Features of Figure 12a and 12b that have been described with reference to an earlier drawing have been given corresponding reference numbers in the 1200 series. In a similar way to the example of Figure 11, the power generation system 1200 includes a container 1201, in this example a standard shipping container. The container 1201 has a footprint, the longitudinal aspect of which is labelled in Figure 12a with reference 1283. The lateral aspect of the footprint is labelled with reference 1284 in Figure 12b. The power generation system 1200 includes a control compartment 1277, which is a portion of an interior volume of the container 1201. The power generation system 1200 also includes a fuel cell compartment 1208, which is within the footprint of the container 1201. A fuel cell 1202 is located within the fuel cell compartment 1208. The fuel cell compartment 1208 is separated from the control compartment 1277 by one or more gas-tight fuel- cell-partitions 1207, which can be considered as defining a gas-tight bulkhead between the control compartment 1277 (which, as discussed above can potentially include a source of ignition) and the fuel cell compartment 1208. The power generation system 1200 further includes a battery compartment 1278, which is a portion of the interior volume of the container 1201 that is defined by one or more battery-partitions 1276. A battery is located within the battery compartment 1278). The one or more battery-partitions 1276 can the same as those described with reference to Figure 11. In this example, a fan 1272 is configured to draw air into the fuel cell compartment 1208 from the battery compartment 1278. In this way, the fan 1272 can reduce the pressure in the battery compartment. Furthermore, the fuel cell compartment 1208 is open to atmosphere in this example. For instance, as shown in Figure 12a, an external wall of the container 1201 (the right-most wall in Figure 12a) can include a sufficient number of louvres or vents such that there is no significant air pressure drop across it. Therefore, as the fan 1272 draws air into the fuel cell compartment 1208 it is immediately exposed to atmosphere. In some examples, an external wall of the container 1201, or a portion of an external wall of the container 1201, can be completely removed such that the fuel cell compartment 1208 is completely open to atmosphere. In this way, the fan 1272 can provide an air flow through the battery compartment 1278 in order to assist with cooling of the batteries, and it can also encourage air flow out of the fuel cell compartment 1208. As discussed above, this provides the advantage that, in the unlikely event that there is a hydrogen leak in the fuel cell compartment 1208, the hydrogen is vented to atmosphere without being exposed to any potential source of ignition in the control compartment 1277. The control compartment 1277 can include any of the components that are described above with reference to Figure 11. In the example of Figure 12, the power generation system 1200 also includes an internal-partition 1285 that partially defines the fuel cell compartment 1208 and also partially defines the battery compartment 1278. The fan 1272 is located in the internal-partition 1285. In this implementation, the internal- partition 1285 is in the same plane as one of the gas-tight fuel-cell-partitions 1207, although it will be appreciated that the power generation system 1200 can be configured differently while still achieving the desired airflow. Irrespective of how open to atmosphere the fuel cell compartment 1208 is, there can be an outflow vent 1286 in an external wall of the container 1207 that defines the fuel cell compartment 1208. In this example, the outflow vent 1286 extends around the corner of two perpendicular walls of the container 1201, as shown in Figures 12a and 12b. Advantageously, the outflow vent 1286 is at an uppermost region of the fuel cell compartment 1201. Since hydrogen is lighter than air, this assists with exhausting any hydrogen in the fuel cell compartment 1208. Further still, in this example, the power generation system 1200 further includes a cowl / ceiling 1282 within the fuel cell compartment 1208 that is angled such that it defines a surface that extends upwards towards the outflow vent 1286. The cowl / ceiling 1282 need not necessarily be planar, as it is shown in Figures 12a and 12b. For example, the cowl / ceiling 1282 can define a curve in either or both of the lateral and longitudinal dimensions, and the curve can be expressed mathematically such that it does not have any turning points. That is, the cowl / ceiling 1282 can define a surface that extends upwards towards the outflow vent 1286 from any position on the surface. In this way, there are no indentations or pockets in the cowl / ceiling 1282 in which hydrogen can accumulate instead of being vented to atmosphere. The shape of the cowl / ceiling 1282 can be is designed to create a passive vacuum which vents air in the fuel cell compartment 1208 to atmosphere and draws air through the battery compartment 1278. The power generation system further comprises a hydrogen flow control valve 1266 that is in a conduit between a hydrogen supply 1206 and the fuel cell 1202. As above, the hydrogen flow control valve 1266 is for reducing the pressure of the hydrogen before it is provided to the fuel cell 1202. Again, as above, an inert gas control system 1281 is used to operate the hydrogen flow control valve 1266. In this example, however, the hydrogen flow control valve 1266 is within the footprint of the container 1201. It can be advantageous to have as many components as possible within the container in terms of being able to transport the container 1201 using existing methods, such as on the back of a lorry as a standard shipping container. The power generation system 1201 can include an inflow vent in an external wall of the container in the same way as described above with reference to Figure 11. The one or more gas-tight fuel-cell-partitions 1207 in this example includes a gas-tight internal-wall-partition that is generally parallel with, and spaced apart from, a second side wall of the container, such that the control compartment 1277 is defined between the internal-wall-partition and the second side wall of the container. In this way, the fuel cell compartment 1208 can be considered as a gas-safe zone (for example an ATEX zone) that is isolated from the control compartment 1277 via an internal gas tight bulkhead, which leaves the fuel cell 1202 open to ambient air. Furthermore, as indicated above, this allows the inert gas control system 1281 and the high-pressure valves 1266 to be brought inside the open-ended vented footprint of the modified container 1201. Returning to Figure 1, we will now describe how rupture panels 187 (which can also be described as emergency vent relief panels) can provide additional safety functionality for the power generation system 100. As discussed above, the power generation system 100 includes a container (in this example a shipping container 101) having an interior volume. The power generation system also includes a fuel cell compartment 108, which is a portion of the interior volume that is defined by one or more fuel-cell-partitions 107 in the container 101. A fuel cell 102 is located within the fuel cell compartment 108. A battery compartment 178 is also provided, which is a portion of the interior volume that is defined by one or more battery-partitions 176. One or more batteries 103 are located within the battery compartment 178. The power generation system 100 also includes a control compartment 177, which is a portion of the interior volume that is: separated from the fuel cell compartment 108 by the one or more fuel-cell-partitions 107; and separated from the battery compartment 178 by the one or more battery-partitions 176. Furthermore, the power generation system includes one or more rupture panels 187 in an exterior wall or ceiling of the container 101. The rupture panels 187 are configured to be removable from respective frames in the exterior wall or ceiling of the container 101 in response to a rapid increase in air pressure within the container, for instance in the very unlikely event that there is an explosion in the container 101. In this way, the pressure within the container 101 can be more moderately relieved. The rupture panels 187 may be affixed to their respective frames by perforated attachment regions that are designed to rupture when a predefined pressure within the container 101 is exceeded. In this example a plurality of rupture panels 187 are located in the ceiling / roof of the container 101, although in other examples there could be rupture panels in an exterior wall of the container 101. In the unlikely event of a gas explosion the internal pressure generated is vented through these sacrificial perforated rupture panels. These rupture panels 187 in the ceiling / roof release the pressure such that the walls of the container 101 remain intact and prevent damage to surrounding areas and / or personal injury to nearby operators. In this example, there is at least one rupture panel located in an exterior wall or ceiling of the container 101 that defines the fuel cell compartment 108. There is also at least one rupture panel located in an exterior wall or ceiling of the container that defines the control compartment. In some examples, the rupture panels 187 have one edge that is more securely affixed to the container 101 than other edges of the rupture panel 187. For instance, perforated regions along one of the edges of the rupture panel 187 may be designed such that they rupture at a higher pressure than the other edges. In this way, if the pressure within the container 101 increases sufficiently to blow the rupture panel 187, it will pivot about the more securely affixed edge and therefore will not be completely separated from the container 101. This is another safety advantage because it reduces the likelihood that the rupture panel 187 itself could cause damage to a person or equipment in the vicinity of the power generation system 100.
Heat Exchanger With reference to Figures 1 and 13, we will now describe how a heat exchanger can advantageously use heat that is extracted from the fuel cell during cooling for a local application that requires heat. In the example of Figure 1, the heat exchanger is located within a fuel cell heat exchanging cooling module 188 that is affixed to an exterior surface of the container 101; in this example the roof of the container 101. As indicated in Figure 1, this fuel cell heat exchanging cooling module 188 can provide a hot water supply 1395. Advantageously, the fuel cell heat exchanging cooling module 188 can be removable from the container 101 to assist with transport of the container 101, especially when the container 101 is a standard sized shipping container. Figure 13 shows schematically an example of a fuel cell cooling circuit. The fuel cell system 1302 includes a fuel cell cooling loop 1388 for removing heat from the fuel cell 1302. The fuel cell can be air cooled or liquid cooled, and therefore the fuel cell cooling loop 1388 can transport a fluid, either a gas or a liquid, to remove heat from the fuel cell. Figure 13 also shows a heat exchanger 1389 for transferring heat from the fuel cell cooling loop 1388 such that it can be used to service a local application that requires heat. The local application can include one or more of: providing a hot water supply; providing space heating; and providing heating for one or more processes. The example that is illustrated in Figure 13 relates to providing a hot water supply, although the skilled person will readily recognise that the heat that is extracted from the fuel cell cooling loop 1388 can be put to good use in numerous other ways. In this example, Figure 13 includes an additional cooling loop 1390 for receiving heat from the fuel cell cooling loop 1388 through the heat exchanger 1389. Furthermore, the additional cooling loop 1390 can selectively heat water in a water tank 1394 such that it can be provided as a hot water supply. In this example there are one or more valves in the additional cooling loop 1390 that are operable to selectively direct fluid in the additional cooling loop 1390 to heat the water in the water tank 1394. More particularly, there are two valves, which will be referred to as hot-water-tank-circuit valves 1391, that, when open, cause fluid in the additional cooling loop 1390 to enter a hot water tank circuit 1397. The hot water tank circuit 1397 includes another heat exchanger 1393 for heating the water in the hot water tank 1394. When the hot-water- tank-circuit valves 1391 are closed, fluid is not moved around the hot water tank circuit 1397. Therefore, the hot-water-tank-circuit valves 1391can be operated to provide a hot water supply on demand. Figure 13 also shows a heat removal component 1396 that selectively transfers heat from the fluid within the additional cooling loop 1390 to atmosphere. In this example, the heat removal component 1396 includes a radiator and a fan to dissipate unused heat. In some examples, the heat removal component 1396 is automatically activated when the temperature of the fluid in the additional cooling loop 1390 exceeds a predetermined setpoint.
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