A novel two-step metal oxide - Metal sulfate water splitting cycle for the production of solar hydrogen

Abstract

This paper reports the thermodynamic analysis of solar H2 production via two-step thermochemical Strontium oxide - Strontium Sulfate (SO-SS) water splitting cycle. The first step belongs to the exothermic oxidation of SrO via SO2 and H2O producing SrSO4 and H2 and second step corresponds to the endothermic reduction of SrSO4 into FeO, SO2, and O2. The products, SrO and SO2 can be recycled to step 1 and hence, reutilized for the production of H2 via water splitting reaction. Thermodynamic equilibrium compositions of the thermal reduction and water splitting reactions were computed as a function of reaction temperatures. Second law thermodynamic analysis was performed to determine the cycle efficiency and solar to fuel energy conversion efficiency attainable without heat recuperation.