Investigations on Thermochemical Energy Storage Based on Manganese-Iron Oxide in a Lab-Scale Reactor

Thermochemical energy storage based on reversible redox reactions of metal oxides constitutes a promising concept to store thermal energy at high temperatures, which renders those storage materials specifically attractive for the implementation in solar tower plants. Only a few experimental studies on lab-scale storage reactors working with metal oxides have been reported. Therefore, an investigation of granular metal oxides in a packed bed storage reactor is presented with regard to thermal storage characteristics and prevalent limitations influencing thermal charging and discharging. Pure manganese oxide and manganese-iron oxide with a Mn/Fe molar ratio of 2:1 are compared as potential storage materials. The main advantages of the binary oxide are derived from the experimental results. Moreover, heat transfer between solid and gas has been identified to be the main limiting factor for the onward reactions of manganese-iron oxide under the applied experimental conditions