Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: In various embodiments, foam is compressed to store energy and/or expanded to recover energy.

Abstract: Pressure swing adsorption (PSA) assemblies with optimized startup times, as well as to hydrogen-generation assemblies and/or fuel cell systems containing the same, and methods of operating the same. Startup and shutdown methods for a PSA assembly, and optionally an associated fuel processing system, are disclosed to provide for shortened startup times. The PSA assemblies may be in fluid communication with a hydrogen source that may be used or otherwise configured or controlled to purge the PSA adsorbent columns of adsorbents during startup and/or shutdown procedures, the hydrogen source additionally or alternatively may be used or otherwise configured or controlled to charge the columns with hydrogen for idling in a pressurized state. The use of this hydrogen source, together with specific startup and shutdown methodologies, provides for reducing the startup time of the PSA assembly.

Abstract: In various embodiments, lined underground reservoirs and/or insulated pipeline vessels are utilized for storage of compressed fluid in conjunction with energy storage and recovery systems.

Abstract: In various embodiments, foam is compressed to store energy and/or expanded to recover energy.

Abstract: In various embodiments, lined underground reservoirs and/or insulated pipeline vessels are utilized for storage of compressed fluid in conjunction with energy storage and recovery systems.

Abstract: Systems and methods for initiating use of, or starting up, fuel cell stacks in subfreezing temperatures. The fuel cell stacks include a thermal management system that is adapted to deliver a liquid heat exchange fluid into thermal communication with a fuel cell stack, such as to heat the stack during startup of the stack when the stack is at a subfreezing temperature or operated in a subfreezing environment. In some embodiments, the thermal management system includes a heat exchange circuit that is configured to provide delivery of the liquid heat exchange fluid to the fuel cell stack even when the conduits are at a subfreezing temperature. In some embodiments, the fuel cell system is configured to deliver liquid heat exchange fluid from the fuel cell stack and heat exchange circuit when the thermal management system is not being utilized.

Abstract: Fuel cell systems and methods for providing power to an energy-consuming device and cooling of the energy-consuming device utilizing the endothermic process of desorbing hydrogen gas from a hydride bed. Fuel cell systems include a fuel cell stack, a hydrogen storage device having a volume of a hydrogen storage material, and a heat exchange system operatively connected to the hydrogen storage device and configured to heat the hydrogen storage material to desorb hydrogen gas therefrom for delivery to the fuel cell stack. The heat exchange system is further configured to deliver a cooled fluid stream to the energy-consuming device for cooling thereof. The cooled fluid stream may be produced, or cooled, by the endothermic desorption of hydrogen gas from the hydrogen storage device. In some fuel cell systems, the heat exchange system utilizes heat from the energy-consuming device to heat the hydrogen storage material for desorption of hydrogen gas therefrom.

Abstract: In various embodiments, valve efficiency and reliability are enhanced via use of hydraulic or magnetic valve actuation, valves configured for increased actuation speed, and/or valves controlled to reduce collision forces during actuation.

Abstract: In various embodiments, valve efficiency and reliability are enhanced via use of hydraulic or magnetic valve actuation, valves configured for increased actuation speed, and/or valves controlled to reduce collision forces during actuation.

Abstract: In various embodiments, valve efficiency and reliability are enhanced via use of hydraulic or magnetic valve actuation, valves configured for increased actuation speed, and/or valves controlled to reduce collision forces during actuation.

Abstract: In various embodiments, foam is compressed to store energy and/or expanded to recover energy.

Abstract: Fuel cell systems and methods for controlling the operation of fuel cell assemblies included therein. In some embodiments, the fuel cell assemblies include a fuel processor and a fuel cell stack, and the fuel cell system includes a control system that controls the operation thereof based upon at least one variable associated therewith. In some embodiments, the variable is associated with the hydrogen (or other product) stream from the fuel processor. In some embodiments, the variable is the pressure of this stream. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within one or more threshold values. In some embodiments, the control system controls the operation of the fuel cell system to maintain the pressure of the hydrogen stream within selected threshold values and to maintain the fuel cell stack's output voltage above a selected threshold.

Abstract: Systems and methods for initiating use of, or starting up, fuel cell stacks in subfreezing temperatures. The fuel cell stacks include a thermal management system that is adapted to deliver a liquid heat exchange fluid into thermal communication with a fuel cell stack, such as to heat the stack during startup of the stack when the stack is at a subfreezing temperature or operated in a subfreezing environment. In some embodiments, the thermal management system includes a heat exchange circuit that is configured to provide delivery of the liquid heat exchange fluid to the fuel cell stack even when the conduits are at a subfreezing temperature. In some embodiments, the fuel cell system is configured to deliver liquid heat exchange fluid from the fuel cell stack and heat exchange circuit when the thermal management system is not being utilized.

Abstract: Hydrogen-producing fuel processing assemblies and fuel cell systems with at least one temperature-responsive valve assembly, and methods for feedback regulation of the hydrogen-producing region. The temperature-responsive valve assembly responds automatically to the temperature of a gas stream of interest to regulate the flow of a subject gas stream therethrough. In some embodiments, these streams are the same streams, while in others, they are different streams. The streams may include at least the reformate stream from a hydrogen-producing region of the fuel processing assembly, the byproduct stream from a purification region, and the product gas stream from the purification region. In some embodiments, the subject gas stream may be the byproduct stream, which is in fluid communication for delivery as a combustible fuel stream for a burner or other heating assembly that produces an exhaust stream to heat the hydrogen-producing region of the fuel processing assembly.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Systems and methods for initiating use of, or starting up, fuel cell stacks in subfreezing temperatures. The fuel cell stacks include a thermal management system that is adapted to deliver a liquid heat exchange fluid into thermal communication with a fuel cell stack, such as to heat the stack during startup of the stack when the stack is at a subfreezing temperature or operated in a subfreezing environment. In some embodiments, the thermal management system includes a heat exchange circuit that is configured to provide delivery of the liquid heat exchange fluid to the fuel cell stack even when the conduits are at a subfreezing temperature. In some embodiments, the fuel cell system is configured to deliver liquid heat exchange fluid from the fuel cell stack and heat exchange circuit when the thermal management system is not being utilized.

Abstract: Fuel cell systems and methods that perform maintenance hydration by supplying power to satisfy at least part of an applied load from an energy-consuming assembly while a primary power source is in electrical communication with and available to supply power to the energy-consuming assembly to satisfy the portion of the applied load. In some embodiments, the systems or methods may determine a start time, or start condition, for hydration of the fuel cell system. Power may be supplied from the activated fuel cell system at an output voltage that is higher than a voltage at which power from the primary power source is being supplied, such that the applied load is satisfied, at least in part, by power from the fuel cell system instead of from the primary power source. Upon operation for a period sufficient to rehydrate the fuel cell stack, operation of the fuel cell system may be discontinued.

Abstract: Fuel cell systems and methods for controlling the operation of components of the fuel cell system, which may include a fuel source and a fuel cell stack. In some examples, a fuel source is adapted to provide supply fuel to a fuel cell stack at a supply pressure. The fuel cell stack produces electric current at a production amperage. In some examples, a control system is adapted to control operation of the fuel cell stack based on a pressure detected at the fuel cell stack. In some examples, a target production amperage is determined based on the detected pressure, such that when electric current is produced at the target production amperage for the detected pressure, the fuel cell stack consumes a predetermined proportion of the supply fuel.

Abstract: Pressure swing adsorption (PSA) assemblies with optimized startup times, as well as to hydrogen-generation assemblies and/or fuel cell systems containing the same, and methods of operating the same. Startup and shutdown methods for a PSA assembly, and optionally an associated fuel processing system, are disclosed to provide for shortened startup times. The PSA assemblies may be in fluid communication with a hydrogen source that may be used or otherwise configured or controlled to purge the PSA adsorbent columns of adsorbents during startup and/or shutdown procedures, the hydrogen source additionally or alternatively may be used or otherwise configured or controlled to charge the columns with hydrogen for idling in a pressurized state. The use of this hydrogen source, together with specific startup and shutdown methodologies, provides for reducing the startup time of the PSA assembly.