High temperature solar thermochemical process for production of stored energy and oxygen based on CuO/Cu2O redox reactions

A novel solar chemical looping air separation (Sol-CLAS) system is proposed here, in which oxygen carrier particles, composed of CuO as the active ingredient and MgAl2O4 as the inert support, are employed to provide both solar thermal energy storage for power generation and to separate oxygen from air. The process has been simulated using codes developed in MATLAB and Aspen Plus software for the average diurnal solar insolation of Port Augusta, South Australia. The simulation predicts that 1000 °C can be achieved in both the solar reduction and oxidation reactors, whose identical temperature results in low exergy destruction. A net cycle efficiency of 46% is predicted with the oxygen co-product of 0.023 m3/MJ of input solar energy. The calculations also show that 81% of the total input solar energy to the system is stored as combined chemical and sensible heat in the oxygen carrier particles. The required enthalpy of reaction is 26% of the net absorbed input solar energy which is stored as chemical heat in the particles and consequently used for oxygen production. The variations of temperature and composition in different flow streams, total flow rate of oxygen produced per day, the amount of particles stored in the tanks, together with the fraction of sensible and chemical storages are also reported. Also reported is the sensitivity to the effects of main operating parameters of reservoir temperature and conversion of particles are also reported.