Abstract: A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.

Abstract: An electrical power supply system has a fuel cell module and a battery. The fuel cell can be selectively connected to the battery system through a diode. The system preferably also has a current sensor and a controller adapted to close a contactor in a by-pass circuit around the diode after sensing a current flowing from the fuel cell through the diode. The system may also have a resistor and a contactor in another by-pass circuit around the diode. In a start-up method, a first contactor is closed to connect the fuel cell in parallel with the battery through the diode and one or more reactant pumps for the fuel cell are turned on. A current sensor is monitored for a signal indicating current flow through the diode. After a current is indicated, a by-pass circuit is provided around the diode.

Abstract: An electrochemical cell has a membrane located between two flow field plates. On a first side of the membrane, there is a porous support surrounded by a seal between the membrane and the flow field plate. There is a gap between the porous support and the seal at the surface of the membrane. On a second side of the membrane, there is a seal between the membrane and the flow field plate located inside of the gap in plan view. The electrochemical cell is useful, for example, in high pressure or differential pressure electrolysis in which the second side of the membrane will be consistently exposed to a higher pressure than the first side of the membrane.

Abstract: An electrolyzer operates within an energy system, for example to provide grid services, energy storage or fuel, or to produce hydrogen from electricity produced from renewable resources. The electrolyzer may be configured to operate at frequently or quickly varying rates of electricity consumption or to operate at a specified power consumption. In one process of operating an electrolyzer, a series of dispatches is received indicating a specified power consumption for a period of time. The dispatches may occur at least once every 30 minutes. The electrolyzer is operated according to the dispatches. Hydrogen produced by the electrolyzer is discharged to a natural gas system.

Abstract: An electrochemical cell stack assembly is disclosed comprising a member made of an elastic and electrically conductive material placed between a bus bar and a starter plate. The elastic, electrically conducting member covers at least a peripheral region along a perimeter of a recess housing the bus bar to distribute compression forces over an interface area between the bus bar and an insulator end plate, thereby reducing shear stresses in the starter plate when the stack is compressed. An elastic pad also may be arranged in the recess and between the insulator end plate and the bus bar.

Abstract: An electrolyzer operates within an energy system, for example to provide grid services, energy storage or fuel, or to produce hydrogen from electricity produced from renewable resources. The electrolyzer may be configured to operate at frequently or quickly varying rates of electricity consumption or to operate at a specified power consumption. In one process of operating an electrolyzer, a series of dispatches is received indicating a specified power consumption for a period of time. The dispatches may occur at least once every 30 minutes. The electrolyzer is operated according to the dispatches. Hydrogen produced by the electrolyzer is discharged to a natural gas system.

Abstract: An electrochemical cell has first and second flow fields on opposite sides of a membrane. The first flow field has a set of generally linear channels in which the flow of a fluid in the field is contained between parallel elongate ridges. The second flow field is defined by a set of parallel discontinuous ridges. Preferably most ridge segments in the second flow field are oblique, for example perpendicular, to and overlap with two or more ridges of the first flow field. The flow fields may be used in, for example, water electrolysis cells including high or differential pressure polymer electrolyte membrane (PEM) electrolysis cells.

Abstract: An electrical power supply system has a fuel cell module and a battery. The fuel cell can be selectively connected to the battery system through a diode. The system preferably also has a current sensor and a controller adapted to close a contactor in a by-pass circuit around the diode after sensing a current flowing from the fuel cell through the diode. The system may also have a resistor and a contactor in another by-pass circuit around the diode. In a start-up method, a first contactor is closed to connect the fuel cell in parallel with the battery through the diode and one or more reactant pumps for the fuel cell are turned on. A current sensor is monitored for a signal indicating current flow through the diode. After a current is indicated, a by-pass circuit is provided around the diode.

Abstract: A fuel cell power module is used to provide nitrogen enriched air for, in one application, fuel tank inerting in an aircraft. The fuel cell power module has a recirculation line between its cathode side outlet and cathode side inlet. At least one controllable device is provided to allow the flow rate in the recirculation line to be controlled. The recirculation flow rate is adjusted such that the cathode exhaust has an oxygen concentration useful for inerting a fuel tank or suppressing fire.

Abstract: A sub-assembly for an electrochemical stack, such as a PEM fuel cell stack, has a bipolar plate with sealing material extending from its upper face, around the edge of the bipolar plate, and onto its lower face. The bipolar plate is preferably a combination of an anode plate and a cathode plate defining an internal coolant flow field and bonded together by sealing material which also provides a seal around the coolant flow field. All of the sealing material in the sub-assembly may be one contiguous mass. To make the sub-assembly, anode and cathode plates are loaded into a mold. Liquid sealing material is injected into the mold and fills a gap between the edge of the plates, and portions of the outer faces of the plates, and the mold. In a stack, sub-assemblies are separated by MEAs which at least partially overlap the sealing material on their faces.

Abstract: A fuel cell module has a hydrogen recirculation pump and a controller. The controller receives a signal indicating the response of the pump to changes in the density or humidity of gasses in the hydrogen recirculation loop. The controller is programmed to consider the signal in controlling one or more balance of plant elements that effect the removal of water from the stack. In a process for operating the fuel cell module, the signal is considered when controlling one or more balance of plant elements that effect the removal of water from the stack. For example, an increase in current drawn from a constant speed or voltage recirculation pump indicates an increase in humidity and suggests that water should be removed from the stack, for example by increasing a coolant temperature set point.

Abstract: A sub-assembly for an electrochemical stack, such as a PEM fuel cell stack, has a bipolar plate with sealing material extending from its upper face, around the edge of the bipolar plate, and onto its lower face. The bipolar plate is preferably a combination of an anode plate and a cathode plate defining an internal coolant flow field and bonded together by sealing material which also provides a seal around the coolant flow field. All of the sealing material in the sub-assembly may be one contiguous mass. To make the sub-assembly, anode and cathode plates are loaded into a mold. Liquid sealing material is injected into the mold and fills a gap between the edge of the plates, and portions of the outer faces of the plates, and the mold. In a stack, sub-assemblies are separated by MEAs which at least partially overlap the sealing material on their faces.

Abstract: Some embodiments of the present invention provide a balance-of-plant system and apparatus suited for regulating the operation of an electrolyzer cell stack. Specifically, in some embodiments, a balance-of-plant system and apparatus is operable to regulate the respective pressures of at least two reaction products relative to one another. Various examples are provided to demonstrate how the respective pressures of two reaction products can be regulated in relation to one another in a pressure following configuration, thereby regulating the pressure differential across an electrolyte layer according to aspects of different embodiments of the invention. Some of the examples provided also include design simplifications and alternatives that may reduce production costs of electrochemical cells configured according to aspects of different embodiments of the invention.

Abstract: A fuel cell module has a hydrogen recirculation pump and a controller. The controller receives a signal indicating the response of the pump to changes in the density or humidity of gasses in the hydrogen recirculation loop. The controller is programmed to consider the signal in controlling one or more balance of plant elements that effect the removal of water from the stack. In a process for operating the fuel cell module, the signal is considered when controlling one or more balance of plant elements that effect the removal of water from the stack. For example, an increase in current drawn from a constant speed or voltage recirculation pump indicates an increase in humidity and suggests that water should be removed from the stack, for example by increasing a coolant temperature set point.

Abstract: A fuel cell module has a hydrogen recirculation pump and a controller. The controller receives a signal indicating the response of the pump to changes in the density or humidity of gassess in the hydrogen recirculation loop. The controller is programmed to consider the signal in controlling one or more balance of plant elements that effect the removal of water from the stack. In a process for operating the fuel cell module, the signal is considered when controlling one or more balance of plant elements that effect the removal of water from the stack. For example, an increase in current drawn from a constant speed or voltage recirculation pump indicates an increase in humidity and suggests that water should be removed from the stack, for example by increasing a coolant temperature set point.

Abstract: An electrochemical cell stack assembly is disclosed comprising a member made of an elastic and electrically conductive material placed between a bus bar and a starter plate. The elastic, electrically conducting member covers at least a peripheral region along a perimeter of a recess housing the bus bar to distribute compression forces over an interface area between the bus bar and an insulator end plate, thereby reducing shear stresses in the starter plate when the stack is compressed. An elastic pad also may be arranged in the recess and between the insulator end plate and the bus bar.

Abstract: A fuel cell module is configured or operated, or both, such that after a shut down procedure a fuel cell stack is discharged and has its cathode electrodes at least partially blanketed with nitrogen during at least some periods of time. If the fuel cell module is restarted in this condition, electrochemical reactions are limited and do not quickly re-charge the fuel cell stack. To decrease start up time, air is moved into the cathode electrodes before the stack is re-charged. The air may be provided by a pump, fan or blower driven by a battery or by the flow or pressure of stored hydrogen. For example, an additional fan or an operating blower may be driven by a battery until the fuel cell stack is able to supply sufficient current to drive the operating blower for normal operation.

Abstract: An electrochemical cell system is provided having: at least one electrochemical cell stack, each stack having at least one reactant fluid inlet; a pressure transmitter arranged in the at least one reactant fluid inlet of each stack; and a control unit for regulating the electrochemical cell system, the control unit receiving at least one signal value from the pressure transmitter indicative of the reactant fluid pressure. The control unit may compare the at least one signal value with a stored values and generate a leak indication based on the rate of pressure decay within the electrochemical cell system. A method of detecting and indicating a leak is also disclosed.

Abstract: A fuel cell module has a hydrogen recirculation pump and a controller. The controller receives a signal indicating the response of the pump to changes in the density or humidity of gasses in the hydrogen recirculation loop. The controller is programmed to consider the signal in controlling one or more balance of plant elements that effect the removal of water from the stack. In a process for operating the fuel cell module, the signal is considered when controlling one or more balance of plant elements that effect the removal of water from the stack. For example, an increase in current drawn from a constant speed or voltage recirculation pump indicates an increase in humidity and suggests that water should be removed from the stack, for example by increasing a coolant temperature set point.

Abstract: A frame assembly for a fuel cell power module, particularly but not exclusively for use in lift trucks, has at least one frame element. The frame element is provided with an internal cavity that is filled with a fill material to provide a desired mass of the frame assembly. The frame assembly is configured to receive a fuel cell stack and other balance of plant components of a fuel cell power module and may also be configured to receive a fuel storage vessel. The frame assembly can be configured so that it can replace a battery pack of a lift truck and still provide adequate counterweight.