Abstract: Hydrogen-producing fuel cell systems and methods of operating the same. The methods include initiating supply of a stored hydrogen stream, which includes stored hydrogen gas, to a fuel cell stack. Prior to the initiating, the stored hydrogen gas is stored in a low-pressure hydrogen storage tank at a hydrogen storage pressure. The methods also include generating an electrical power output from the stored hydrogen gas with the fuel cell stack. The methods further include, during a supply time interval that is subsequent to the initiating, monitoring a hydrogen supply variable that is indicative of flow of the stored hydrogen stream to the fuel cell stack. The methods also include detecting a change in the hydrogen supply variable and responding to the detecting. The systems include a controller that is programmed to perform the methods.

Abstract: Hydrogen-producing fuel processing systems and related methods. The systems include a hydrogen-producing region configured to produce a mixed gas stream from a feedstock stream, a hydrogen-separation membrane module having at least one hydrogen-selective membrane and configured to separate the mixed gas stream into a product hydrogen stream and a byproduct stream, and an oxidant delivery system configured to deliver an oxidant-containing stream to the hydrogen-separation membrane module in situ to increase hydrogen permeance of the hydrogen-selective membrane.

Abstract: Membrane-based hydrogen purifiers having graphite frame members. The purifiers include a hydrogen-separation membrane module with at least one membrane cell containing at least one hydrogen-selective membrane, which includes a permeate face and an opposed mixed gas face, and a fluid-permeable support structure that physically contacts and supports at least a central region of the permeate face. The membrane cell further includes a permeate-side frame member and a mixed gas-side frame member. The permeate-side frame member is interposed between the hydrogen-selective membrane and the fluid-permeable support structure to physically contact a peripheral region of the permeate face and a peripheral region of the fluid-permeable support structure. The mixed gas-side frame member physically contacts a peripheral region of the mixed gas face. At least one of the permeate-side frame member and the mixed gas-side frame member is a graphite frame member.

Abstract: Hydrogen-producing fuel processing systems and related methods. The systems include a hydrogen-producing region configured to produce a mixed gas stream from a feedstock stream, a hydrogen-separation membrane module having at least one hydrogen-selective membrane and configured to separate the mixed gas stream into a product hydrogen stream and a byproduct stream, and an oxidant delivery system configured to deliver an oxidant-containing stream to the hydrogen-separation membrane module in situ to increase hydrogen permeance of the hydrogen-selective membrane.

Abstract: Hydrogen-producing fuel cell systems (HPFCS) and methods. The HPFCS includes a fuel processor configured to produce generated hydrogen gas, a hydrogen storage device configured to contain stored hydrogen gas, and a fuel cell stack configured to produce an initial electrical output from the stored hydrogen gas and an oxidant and to produce a subsequent electrical output from the generated hydrogen gas and the oxidant. The methods include detecting an inability of a primary power source to satisfy an applied load. Responsive to the detecting, the methods include initiating a startup of the fuel processor, supplying stored hydrogen gas to the fuel cell stack to produce the initial electrical output, satisfying the applied load with the initial electrical output, supplying generated hydrogen gas to the fuel cell stack after the startup to produce a subsequent electrical output, and satisfying the applied load with the subsequent electrical output.

Abstract: Membrane-based hydrogen purifiers having graphite frame members. The purifiers include a hydrogen-separation membrane module with at least one membrane cell containing at least one hydrogen-selective membrane, which includes a permeate face and an opposed mixed gas face, and a fluid-permeable support structure that physically contacts and supports at least a central region of the permeate face. The membrane cell further includes a permeate-side frame member and a mixed gas-side frame member. The permeate-side frame member is interposed between the hydrogen-selective membrane and the fluid-permeable support structure to physically contact a peripheral region of the permeate face and a peripheral region of the fluid-permeable support structure. The mixed gas-side frame member physically contacts a peripheral region of the mixed gas face. At least one of the permeate-side frame member and the mixed gas-side frame member is a graphite frame member.

Abstract: Hydrogen-producing fuel processing systems and related methods. The systems include a hydrogen-producing region configured to produce a mixed gas stream from a feedstock stream, a hydrogen-separation membrane module having at least one hydrogen-selective membrane and configured to separate the mixed gas stream into a product hydrogen stream and a byproduct stream, and an oxidant delivery system configured to deliver an oxidant-containing stream to the hydrogen-separation membrane module in situ to increase hydrogen permeance of the hydrogen-selective membrane.

Abstract: Hydrogen-producing fuel cell systems (HPFCS) and methods. The HPFCS includes a fuel processor configured to produce generated hydrogen gas, a hydrogen storage device configured to contain stored hydrogen gas, and a fuel cell stack configured to produce an initial electrical output from the stored hydrogen gas and an oxidant and to produce a subsequent electrical output from the generated hydrogen gas and the oxidant. The methods include detecting an inability of a primary power source to satisfy an applied load. Responsive to the detecting, the methods include initiating a startup of the fuel processor, supplying stored hydrogen gas to the fuel cell stack to produce the initial electrical output, satisfying the applied load with the initial electrical output, supplying generated hydrogen gas to the fuel cell stack after the startup to produce a subsequent electrical output, and satisfying the applied load with the subsequent electrical output.

Abstract: Systems and methods for forming a liquid mixture having a predetermined mix ratio and reforming systems, reforming methods, fuel cell systems, and fuel cell methods that utilize the liquid mixture. The methods include apportioning a preselected volume of liquid from a liquid source. During the apportioning, the liquid is a first liquid, and the methods further include providing a first preselected volume of the first liquid to a mix tank. The methods also include repeating the apportioning with a second liquid providing a second preselected volume of the second liquid to the mix tank to generate the liquid mixture. The methods also may include providing the liquid mixture to a reforming region, reforming the liquid mixture to generate a mixed gas stream that includes hydrogen gas, and providing the hydrogen gas to a fuel cell assembly to generate an electric current.