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: Hydrogen-producing fuel cell systems with load-responsive feedstock delivery systems, and methods for regulating the delivery of feedstock to the hydrogen-producing region of a fuel cell system. The fuel cell systems include a control system that is adapted to monitor and selectively regulate the rate at which the feedstock is delivered to a hydrogen-producing region of a hydrogen generation assembly. The control systems, and corresponding methods, include feed-forward and feedback control portions that cooperatively regulate the rate at which the feed stream is delivered to the hydrogen generation assembly responsive at least in part, if not completely, to the fuel cell stack's demand for hydrogen gas and the rate at which the produced hydrogen gas is consumed by the fuel cell stack.

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 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 being satisfied by the fuel cell system. In some embodiments, a fuel cell system may determine a start time, or start condition, for maintenance of the fuel cell system. The fuel cell system then may be activated from an inactive condition according to the start time, or start condition, by initiating delivery of at least fuel, and optionally oxidant, to a fuel cell stack of the system.

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 is adapted to automatically respond 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 a heated exhaust stream to heat the hydrogen-producing region of the fuel processing assembly.

Abstract: Fuel cell systems 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 being satisfied by the fuel cell system. In some embodiments, a fuel cell system may determine a start time, or start condition, for maintenance of the fuel cell system. The fuel cell system then may be activated from an inactive condition according to the start time, or start condition, by initiating delivery of at least fuel, and optionally oxidant, to a fuel cell stack of the system.

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 more particularly to fuel cell systems with fuel cell hydration provided during periods of inactivity by combining a fuel and an oxidant. In some embodiments, the systems may include at least one fuel cell with an anode region and a cathode region. The at least one fuel cell may be hydrated by disposing both a fuel and an oxidant in the anode region, the cathode region, or both the anode region and the cathode region, and, optionally, without generation of electrical output. In some embodiments, the systems may include a controller that controls combined delivery of a fuel and an oxidant to the at least one fuel cell. In some embodiments, the systems may deliver a mixture of the fuel and the oxidant to the at least one fuel cell after a period of fuel cell inactivity.

Abstract: Systems and methods for monitoring and/or controlling fuel cell exhaust to provide a non-flammable exhaust stream. In some embodiments, operation of the fuel cell system is regulated to provide an exhaust stream that has a maximum flammability that is less than a predetermined fractional threshold of the lower flammability limit for the gases contained therein. In some embodiments, the systems and methods utilize the current produced by the fuel cell, or fuel cell stack, to monitor and/or regulate the flammability of the fuel cell exhaust stream. In some embodiments, the fuel cell system includes one or more controllers that are adapted to monitor the flammability of the exhaust stream from the fuel cell stack and/or to regulate the operation of the fuel cell system responsive thereto. In some embodiments, the operation and/or duty cycle of at least an anode purge valve is regulated or controlled responsive to the measured current.

Abstract: Hydrogen-producing fuel cell systems with load-responsive feedstock delivery systems, and methods for regulating the delivery of feedstock to the hydrogen-producing region of a fuel cell system. The fuel cell systems include a control system that is adapted to monitor and selectively regulate the rate at which the feedstock is delivered to a hydrogen-producing region of a hydrogen generation assembly. The control systems, and corresponding methods, include feed-forward and feedback control portions that cooperatively regulate the rate at which the feed stream is delivered to the hydrogen generation assembly responsive at least in part, if not completely, to the fuel cell stack's demand for hydrogen gas and the rate at which the produced hydrogen gas is consumed by the fuel cell stack.

Abstract: PSA assemblies with at least one energy recovery assembly, as well as hydrogen-generation assemblies and/or fuel cell systems containing the same, and methods of operating the same. The energy recovery assemblies are configured to recover mechanical energy from the product hydrogen stream and to apply the recovered mechanical energy to one or more components of the PSA assembly, the hydrogen-generation assembly, and/or the energy producing system. In some embodiments, the energy recovery assembly includes a gas motor configured to recover mechanical energy from the product hydrogen stream produced by the PSA assembly. In some embodiments, the gas motor operates among a plurality of operating states based, at least in part, on the pressure of the product hydrogen stream. In some embodiments, the energy recovery assembly is configured to apply the recovered mechanical energy to at least a vacuum pump.

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: 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: Assemblies and methods for monitoring the voltage condition of a fuel cell device. The monitoring may be provided without direct electrically conductive or mechanical contact with the fuel cell device. This may be provided by a detector coupled to a pair of electrical contacts on a fuel cell device that is adapted to produce electromagnetic energy, or radiation, indicative of the voltage between the pair of electrical contacts. Accordingly, a monitor that is spaced from the detector may be used to detect the produced electromagnetic energy and produce an output signal representative of the voltage difference. In some examples, a plurality of fuel cell devices or overlapping sets of fuel cell devices may be monitored. A digital signal may be generated, providing a simplified indication of the operating condition of one or a plurality of fuel cell devices. Multiple digital signals may be used to provide additional information.

Abstract: Fuel cell systems that include at least one fuel cell stack adapted to receive a fuel stream containing hydrogen gas or other proton source, and an oxidant stream containing oxygen gas. The systems include an oxidant supply system adapted to deliver an enriched, or concentrated, oxidant stream to the fuel cell stack. In some embodiments, the oxidant supply system is adapted to receive an air stream and produce an oxygen-enriched stream therefrom. In some embodiments, the fuel cell system includes a water-recovery system adapted to recover water produced in the fuel cell stack, such as may be recovered from the cathode exhaust stream from the fuel cell stack. In some embodiments, the recovered water is utilized as at least a portion of a feed stream for the fuel cell system, such as for a reformer or electrolyzer that produces hydrogen used as fuel for the fuel cell stack.

Abstract: A steam reformer that produces hydrogen gas from water and a carbon-containing feedstock, such as an alcohol or a hydrocarbon. The steam reformer includes a hydrogen-producing region, in which a mixed gas stream containing hydrogen gas and other gases is produced from water and a carbon-containing feedstock. The steam reformer includes a separation region, in which the mixed gas stream is separated into a hydrogen-rich stream containing at least substantially pure hydrogen gas, and a byproduct stream containing at least a substantial portion of the other gases. In some embodiments, the steam reformer is a vertically oriented fuel processor. In some embodiments, the separation region includes at least one hydrogen-selective membrane. In some embodiments, the steam reformer further includes a polishing region, in which the hydrogen-rich stream produced in the separation region is further purified. In some embodiments, the reformer includes an external metal or sealed ceramic shell.

Abstract: Feedstock delivery systems for fuel processors, and fuel processing systems incorporating the same. In some embodiments, the feedstock delivery system includes at least one pressurized tank or other reservoir that is adapted to store in liquid form a feedstock for a fuel processor. The delivery system further includes a pressurization assembly that is adapted to pressurize the reservoir by delivering a stream of pressurized gas thereto. In some embodiments, the gas is at least substantially comprised of nitrogen or other inert gases. In some embodiments, the gas is a nitrogen-enriched or a reduced-oxygen air stream. In some embodiments, the delivery system includes a sensor assembly that is adapted to monitor the concentration of oxygen in, and/or being delivered to, the reservoir(s). In some embodiments, the delivery system includes a pumpless delivery system that regulates the delivery under pressure of the feedstock from the tank to the fuel processor.