Abstract: An arrangement for replenishing hydrogen consumed in a fuel cell device includes a reaction vessel that contains a quantity of a material that releases hydrogen on contact with water in a highly exothermic reaction. A hydrogen-containing gaseous medium is passed through the material quantity under conditions resulting in removal of heat from the material quantity by convection at a heat removal rate sufficient to maintain a temperature differential between an inlet portion and an outlet portion of the reaction vessel below a predetermined level. This includes recirculating a portion of the gaseous medium from the outlet portion to the inlet portion and cooling at least the recirculated portion.

Abstract: A regenerative fuel cell assembly is provided in which a fuel cell is integrated with an electrolysis cell. In a preferred embodiment the fuel cell assembly and electrolysis cell assembly are spaced apart and have their hydrogen electrodes in facing relationship; a water transport matrix is disposed in the space between the hydrogen electrodes, and a water storage matrix is disposed adjacent the oxygen electrode of the fuel cell. During operation of the fuel cell the water storage matrix holds the water produced by the fuel cell; during electrolysis cell operation the water in the water storage matrix passes to the water transport matrix which carries it to the electrolysis cell where it is consumed.