Generation of hydrogen gas from a borohydride at a constant temperature using the phase transition of a hydrate

The present subject matter provides heat management while generating hydrogen gas from a hydride achieved by coupling a hydride with a hydrate. The present subject matter unexpectedly provides improved methods so that the heat released by the hydride during hydrolysis is accurately balanced by the heat absorbed by the hydrate as the hydrate undergoes a phase transition to a less hydrated or to an anhydrous form. Examples of heat-moderated hydrogen generating systems are provided, and include, among others: NaBH4/Na2SO4.10H2O, NaBH4/CoSO4.7H2O, and NaBH4/FeSO4.7H2O. The subject matter provides a methodology for determining the correct proportions of hydride/hydrate to use in preparing a hydrogen generator capable of operating at a nearly constant temperature at or near a phase transition temperature of the hydrate or at a higher temperature that is still within a desired temperature range, such as, for example, 30-90° C.