NOVELTY - An electrolyzer (30) for generating hydrogen gas by electrolysis of steam, comprises: (a) electrolysis cells (38) in communication with a distributor of steam; (b) one or more energy guides disposed within the electrolyzer for directing radiant energy to irradiate the electrolysis cells so the electrolysis cells absorb thermal energy to facilitate electrolysis in the electrolysis cells; and (c) a hydrogen gas collector for collecting hydrogen gas generated by the electrolysis cells.    USE - The electrolyzer, apparatus, and methods are useful for generating hydrogen gas by electrolysis of steam; and for producing electricity from solar radiation (all claimed).    ADVANTAGE - The invention provides apparatus and method for practical generation of hydrogen gas with improved energy efficiency.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are:    (1) an apparatus for generating hydrogen gas by electrolysis of water or steam, comprising: (a) an electrolyzer having: (i) electrolysis cells in communication with a distributor of steam; (ii) one or more energy guides disposed within the electrolyzer for directing radiant energy to irradiate the electrolysis cells so that the electrolysis cells absorb thermal energy to facilitate electrolysis in the electrolysis cells; and (iii) a hydrogen gas collector for collecting hydrogen gas generated by the electrolysis cells; and (b) an energy concentrator for collecting and concentrating radiant energy from a source for use in the electrolyzer as an energy source;    (2) a method of generating hydrogen gas from steam, comprising: (a) passing steam through electrolysis cells located within an electrolyzer and electrolyzing the steam to produce hydrogen gas; and (b) directing radiant energy within the electrolyzer to irradiate the electrolysis cells with the radiant energy, and thus heating the electrolysis cells to facilitate electrolysis of the steam;    (3) hydrogen gas produced by the method above; and    (4) a method of producing electricity from solar radiation using the apparatus above comprising using the collected hydrogen gas to produce electricity in a fuel cell or turbine generator to supplement the electricity produced directly from the converter.    DESCRIPTION OF DRAWING(S) - The drawing shows a cut-away perspective view of electrolyzer.    Electrolyzer (30)    Outlet (34)    Collection manifold (35)    Oxygen gas outlet (36)    Electrolysis cells (38)    Light rods (44)