A device for utilizing solar energy either by absorption or reflection of the incident radiation. Several types have been developed for both domestic and industrial application. Some are in the experimental stage. (1) Collection units consisting of a blackened absorber surface enclosed by one or two layers of silvered glass or polished aluminum, which admit the incident radiation but prevent the escape of heat; the energy absorbed is transferred to air or water circulating between the glass plates and the absorber. (2) Energy-focusing systems (solar towers) in which the incident radiation is concentrated on a central receiver from an array of flat or parabolic mirrors. This method is utilized for evaporating low-level radioactive wastewater at Los Alamos, as well as in a power generating plant.Solar energy has important possibilities for chemical synthesis. A prototype collector for producing ammonia from the reduction of nitrogen and water at low temperature and pressure has been reported. This reaction isN2+3H2O→TiO2hv2NH3+1.5O2
