NOVELTY - A hydrogen generation system (1) comprises a reformer assembly (2) having a process inlet receiving a fuel and producing a reformate gas; an hydrogen (H2) purification unit (3) receiving the reformate gas from the reformer assembly and separating pure H2 from the reformate gas and having a pure H2 outlet and an off-gas outlet; and an H2 storage unit (4) connected to the H2 purification unit to pure H2 outlet receiving the pure H2. The H2 storage unit has an outlet selectively connectable to the reformer assembly process inlet.    USE - As a hydrogen generation system useful in e.g. fuel cell system and hydrogen refueling station.    ADVANTAGE - The fuel system minimizes the potential for solid carbon formation in a compact hydrogen generation system. The storage configuration has an outlet selectively connectable to the reformer assembly process inlet during startup without the need for a spark igniter. The system establishes a backpressure on the reformer catalyst section and vaporizer section decreases the hydrogen flow from the H2 storage unit until no further demand of H2. The system and startup process eliminates any need for spark ignition, burners, or other heating mechanisms, thus simplifying the overall system design and operation. The hydrogen generation system is compact, has low capital cost, highly effect and water sufficient while hydrogen hydrogen generation systems are required to be compact, low capacity, low capital cost, highly efficient, and water self-sufficient while being operated as transient load following units and potentially daily on/off cycles. The system facilitates a unique startup procedure that manages to achieve the requirements of compact hydrogen generation systems while minimizing the potential for carbon formation during startup, enhances heat transfer to the reactor, and supports catalyst reduction. The hydrogen storage unit provides sufficient hydrogen to fuel the combustor section during the startup transient period in which proper temperature profiles are still being established within the reformer catalyst section and such process fuel can be reformed and used to drive the combustion process. The system provides increased hydrogen concentration within the reformer's catalyst section during the critical startup stages when the flow of fuel begins and temperature profiles are not fully established. Increasing the H2 concentration in the gas phases uniquely improves the equilibrium of the desired reactions and decreases the equilibrium of the undesired reactions. Hydrogen prevents carbon formation pathways when the feed fuel contains non-saturated hydrocarbons and aromatics, because the hydrogen can react with the carbon-carbon double bonds. The flow of hydrogen through the reformer serves as a thermal energy carrier helping to provide convective heat transfer and distribution throughout the vaporizer and reformer catalyst sections. The mass flow of hydrogen through the vaporization section supports the transport of water vapor throughout the catalyst sections and helps minimize condensation on surfaces before temperature profiles are established throughout the reformer. Hydrogen fueled startups do not require additional equipment or hardware and can proceed at a rate limited only be the mechanical design of the reformer system hardware. Use of hydrogen gas in process as a thermal transport medium within the catalyst bed helps provide the distribution of heat and helps to maintain a more uniform temperature profile such that the potential for hot spots are minimized. The pressure swing adsorption (PSA) unit can be operated at various feed flow rates, feed pressures, and cycle speeds to achieve variations in the system backpressure, hydrogen recovery, and therefore, the relative flow between the product and off-gas flow connections.    DETAILED DESCRIPTION - A hydrogen generation system (1) comprises a reformer assembly (2) having a process inlet receiving a fuel and producing a reformate gas; an hydrogen (H2) purification unit (3) receiving the reformate gas from the reformer assembly and separating pure H2 from the reformate gas and having a pure H2 outlet and an off-gas outlet; and an H2 storage unit (4) connected to the H2 purification unit to pure H2 outlet receiving the pure H2. The H2 storage unit has an outlet selectively connectable to the reformer assembly process inlet. The off-gas outlet is connected to a combustor section within the reformer assembly along with a combustion air source. The reformer assembly comprises a vaporization section (12) for receiving and vaporizing water or water and fuel and passing the vapor to a reformer catalyst section heated by a combustor section fueled by the off-gas from the H2 purification unit along with combustion air source. An INDEPENDENT CLAIM is included for a startup process involving generating heat in the combustor section of the reformer assembly by passing H2 from the H2 storage unit through the reformer catalyst section, where the H2 purification unit and through the off-gas connection to the combustor section. The combustion exhaust from the combustor section passes through the vaporization section to ensure the water and fuel is fully vaporized during normal system operation. In the system, during startup operation a portion of H2 from the H2 storage unit is mixed with water in the vaporization section. The H2 purification unit is pressure swing absorption.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the hydrogen generation and purification system.    generation system (1)    reformer assembly (2)    purification unit (3)    storage unit (4)    vaporization section (12)    connection. (37)