NOVELTY - The method involves disposing at least one reactant in a substrate comprising graphite or boron carbide, heat-treating the substrate to form a diffusion multiple, contacting the diffusion multiple with hydrogen having at least two phases, detecting any absorption of hydrogen, and/or detecting any desorption of hydrogen. The reactant is lithium, magnesium, sodium, potassium, calcium and/or aluminum.    USE - For determining capability of light metal carbides, borocarbides and carbonitrides to absorb and desorb hydrogen carbides used for storage of energy and for energy generation device (claimed) such as fuel cell used in automobiles and domestic appliances, and gas turbines.    ADVANTAGE - The method facilitates formation of large number of controlled compositional variations in bulk samples for fast and systematic surveys of bulk properties of carbides. The combinatorial method of determining the capability of light metal carbides, borocarbides and carbonitrides to absorb and desorb hydrogen is quick and efficient.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) a method of recovering hydrogen involves contacting a compound comprising a carbide in hydrogen to form a hydrogenated compound. The compound is selected from carbides (C) such as Al4C3, Na4C3, Li4C3, K4C3, LiC6, Mg2C3, MgC2, AlTi2C, AlTi3C, AlZrC2, Al3Zr5C, Al3Zr2C4, Al3Zr2C7, KC4 and/or NaC4, and heating the hydrogenated compound to recover the hydrogen;    (2) energy generation device for generating energy;    (3) diffusion multiple containing compounds having formula (II) (Lia, Nab, Kc, Ald, Mge, Caf)x (B, N, C)y where a-f is 0-1 and x and y have values of about 1-22;    (4) a composition comprising a hydride of a compound and at least one carbide compound (C); and    (5) a system for storage and recovery of hydrogen, comprising a hydrogen generation reactor in fluid communication with a hydride cycle reactor. The hydrogen generation reactor utilizes hydrides of light metal carbides to recover hydrogen.    DESCRIPTION OF DRAWING(S) - The figure shows the schematic diagram of the system for generation of hydrogen from hydrides of light metal carbides.