Exploitation of thermochemical cycles based on solid oxide redox systems for thermochemical storage of solar heat. Part 4: Screening of oxides for use in cascaded thermochemical storage concepts

摘要

Air-operated Solar Tower Power Plants store the excess solar energy during on-sun operation as sensible heat in porous solid materials that function as recuperators during off-sun operation. Their storage capacity can be extended by coating or manufacturing the porous heat exchange modules with oxides of multivalent metals undergoing reduction/oxidation (redox) reactions accompanied by significant heat effects (e.g. Co3O4/CoO, BaO2/BaO, Mn2O3/Mn3O4, CuO/Cu2O). Furthermore, to maximize the amount of redox material that can be thermochemically exploited efficiently in a given thermochemical reactor volume, the idea of employing cascades of porous structures, incorporating different redox oxide materials and distributed in a certain rational pattern in space tailored to their thermochemical characteristics and the local temperature of the heat transfer medium is set forth.