Computational Thermodynamic Analysis of Solar Fuel Production Via Metal Oxide Based H2O and CO2 Splitting Thermochemical Cycles

Solar fuel production via thermochemical H₂O and/or CO₂ splitting cycles is one of the potential options for the storage of solar energy into chemical energy, which can be further used for the fulfillment of present/future energy demand. In this study, computational thermodynamic analysis of the two-step metal oxide based solar thermochemical H₂O and/or CO₂ splitting process was performed with the help of commercial thermodynamic softwares. The thermodynamic equilibrium compositions for the metal oxide based solar thermochemical H₂O and/or CO₂ splitting process were determined at different experimental conditions. Influence of various process parameters such as temperatures, pressures, reactants/carrier gas flowrates, and etc. was investigated in detail. In addition, variations in the reaction enthalpy and Gibbs free energy and conversion of H₂O and/or CO₂ into H₂, CO, or syngas during solar thermochemical cycles were also studied in detail. To design the solar reactor with maximum possible efficiency, second law analysis of this process was also studied and the effects of various operating parameters on solar absorption efficiency of the solar reactor, solar energy input to the solar reactor, rediation heat losses from the solar reactor, net energy absorbed in the solar reactor, rates of entropy produced in the solar reactor and heat exchangers were calculated and plotted. The solar-to-fuel conversion efficiency for the metal oxide based solar thermochemical H₂O and/or CO₂ splitting process was determined and compared with previously investigated thermochemical cycles. Attempts were made to identify the most promising MO system with maximum process efficiency.