Solar thermal production of zinc: Program strategy and status of research

The solar thermal production of zinc is considered for the conversion of solar energy into storable and transportable chemical fuels. The ultimate objective is to develop a technically and economically viable technology that can produce solar zinc. The program strategy for achieving such goal involves research in two paths: a direct path via the solar thermal splitting of ZnO, and an indirect path via the solar carbothermal and CH₄-thermal reduction of ZnO. The chemical thermodynamics and kinetics for both paths are briefly reviewed. A vortex-flow solar reactor for reducing ZnO with CH₄ is also described. Solar tests conducted at PSI solar furnaces in the temperature range 1000-1600 K yielded high chemical conversion to zinc.