TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Electrolyzer: In the electrolyzer above, the energy guides are located in close proximity to surfaces of the respective electrolysis cells. The electrolysis cells are generally elongate and the energy guides are generally elongate and disposed generally parallel to the electrolysis cells. The energy guides have a textured surface that disperses at least some incident radiation from within the energy guide to externally of the energy guide, where the dispersed radiation falls incident upon the one or more electrolysis cells and heats the electrolysis cells. The textured surface has a surface roughness in the range of 1 mu m to a few millimeters; or the textured surface has a surface roughness in the range of 1-500 mu m. It comprises a surface formed by sandblasting or acid etching. Each energy guide comprises quartz, crystal or an amorphous glass-product. The electrolysis cells are arranged in a hexagonal array about each energy guide. The energy guides collectively define a light-receiving surface on which radiation is directed for transmitting radiant energy through the energy guides for direction onto the electrolysis cells. Each energy guide has an end portion with a dove-tail longitudinal profile for collecting radiant energy into the energy guide; or each energy guide has a section profile for forming the light-receiving surface in combination with other energy guides. The section profile is hexagonal and the energy guides are formed as rods; or the section profile is rectangular and the energy guides are formed as panels. The light-receiving surface is generally continuous. The energy guide comprises a surface layer formed on each electrolysis cell and having selected reflective properties to reflect part of the incident radiant energy and to transmit part of the incident radiant energy onto the electrolysis cells, thus heating the electrolysis cells. The reflective properties of the surface layer may be selected to control the level of reflected and transmitted radiant energy, and particularly in view of geometrical dimensions and relative arrangement of electrolysis cells. An energy density transmitted to the electrolysis cells is controlled with regard to the concentration of the radiant energy, energy guide reflective properties and total surface area of the electrolysis cells. The energy density is controlled to be in the range of 0.1 to 2 W/cm2 on the surface of electrolysis cells; or the energy density is controlled to be about 1 W/cm2. One or more energy guides facilitate electrolysis in the electrolysis cells at a temperature of greater than 700 degrees C. Preferred Apparatus: The apparatus further comprises: (c) a convertor that converts the radiant energy into electrical energy and that is electrically linked to the electrolysis cells to supply the electrical energy to the electrolysis cells; and (d) a separator that is interposed between the energy concentrator and the convertor for receiving and separating the concentrated radiant energy into a first band of short wavelength radiation and a second band of long wavelength radiation and directing the first band to the convertor and directing the second band to the one or more energy guides. Preferred Method: The method involves operating the electrolysis cells with electrical energy converted from the radiant energy. It also involves dividing the radiant energy into a first band of short wavelength radiation and a second band of long wavelength radiation and converting the first band of short wavelength radiation into electrical energy and supplying steam and the electrical energy to the electrolysis cells to electrolyze the steam. Step (b) involves directing the second band of long wavelength radiation through one or more energy guides to disperse the long wavelength radiation to irradiate the electrolysis cells. The method involves controlling the energy density of long wavelength radiation that irradiates the electrolysis cells by selecting a concentration of the radiant energy, a reflectivity of the one or more energy guides and a total surface area of the electrolysis cells. It further comprises controlling the energy density to be in the range of 0.1 to 2 W/cm2 on the surface of electrolysis cells; or controlling the energy density to be about 1 W/cm2. Step (b) involves directing the radiant energy to irradiate and heat the electrolysis cell to a temperature of about 1000 degrees C.