NOVELTY - The method comprises coupling a hydrogen gas storage system to an end-use application that utilizes hydrogen, maintaining the hydrogen gas storage system at a temperature and a pressure, where the hydrogen gas storage system comprises a quantity of hydrocarbon source and a quantity of lithium hydride, and altering the temperature and/or pressure of the hydrogen gas storage system to cause the quantity of the hydrocarbon source to react with the quantity of lithium hydride to generate a quantity of hydrogen and a perlithiohydrocarbon compound when the end-use application requires hydrogen.    USE - The method is useful for determining hydrocarbon gases to evolve hydrogen, which is useful in an end-use application including a stationary power source, a mobile power source, a remote power source, a low signature power source, an auxiliary fuel cell, an automotive fuel cell, an automotive fuel cell coupled to a combustion engine, a stationary cell and a fuel cell powered portable electronic device, where the end-use application is useful in aerospace applications.    ADVANTAGE - The method is capable of determining the hydrocarbon gases in an efficient manner thus rapidly evolving hydrogen with less consumption of heat energy.    DETAILED DESCRIPTION - The method comprises coupling a hydrogen gas storage system to an end-use application that utilizes hydrogen, maintaining the hydrogen gas storage system at a temperature and a pressure, where the hydrogen gas storage system comprises a quantity of hydrocarbon source and a quantity of lithium hydride, altering the temperature and/or pressure of the hydrogen gas storage system to cause the quantity of the hydrocarbon source to react with the quantity of lithium hydride to generate a quantity of hydrogen and a perlithiohydrocarbon compound when the end-use application requires hydrogen, removing the generated quantity of hydrogen from the hydrogen gas storage system to the end-use application, and replenishing the quantity of the hydrocarbon source within the hydrogen gas storage system. The replenishing step comprises introducing a second quantity of hydrogen to the hydrogen gas storage system, and adjusting the temperature or the pressure or both of the hydrogen gas storage system to cause the second quantity of hydrogen to react with the perlithiohydrocarbon compound to generate lithium hydride and a second quantity of a hydrocarbon source. The altering step comprises heating the quantity of the hydrocarbon source and the quantity of lithium hydride to an elevated temperature sufficient to cause the quantity of the hydrocarbon source to react with the lithium hydride to generate a quantity of hydrogen and a perlithiohydrocarbon compound, and increasing a pressure within the hydrogen gas storage system to an elevated pressure sufficient to cause the quantity of the hydrocarbon source to react with the lithium hydride to generate the quantity of hydrogen and the perlithiohydrocarbon compound. The method further comprises determining a first list of hydrocarbon sources that generates a release of 19 wt.% of hydrogen from the hydrocarbon source when the hydrocarbon source is reacted with a quantity of lithium hydride, determining whether a second list of the hydrocarbon sources from the first list of the hydrocarbon sources are relatively stable and unreactive with lithium hydride at a predetermined temperature and a predetermined pressure, selecting (35) one of the hydrocarbon sources from the second list that is not highly exothermic or highly endothermic at the predetermined pressure, and introducing the quantity one hydrocarbon sources to the hydrogen gas storage system. An INDEPENDENT CLAIM is included for a product such as a hydrogen storage system.    DESCRIPTION OF DRAWING(S) - The figure shows a flow chart of a method for determining the hydrocarbon gases to evolve hydrogen.    Determining end use application (20)    Determining acceptable operating conditions for end use application (25)    Determination of reaction kinetics associated with hydrogen evolution (30)    Selecting hydrogen source (35)    Creating hydrogen storage system. (45)