A new concept for hybrid sensible/thermochemical storage of solar heat in cascaded redox-oxide-based thermochemical reactors/heat exchangers

Abstract

The current work is a follow-up of ideas introduced already in the literature, namely of combining active thermochemical redox oxide pairs (e.g. Co3O4/CoO, Mn2O3/Mn3O4, CuO/Cu2O) with porous ceramic structures in order to effectively store solar heat in air-operated Solar Tower Power Plants. If such oxides are coated on porous heat exchange modules, solar heat produced during on-sun operation can be used to power the endothermic reduction of the oxide; the thermal energy can be entirely recovered by the reverse exothermic oxidation reaction during off-sun operation. Thus the storage concept is rendered from “purely” sensible to a “hybrid” sensible/thermochemical one. In addition, the construction modularity of the current state-of-the-art sensible storage systems provides for the implementation of concepts like spatial variation of redox oxide materials chemistry along the reactor/heat exchanger, to enhance the utilization of the heat transfer fluid