(706g) Solar Driven Iron Oxide Based Thermochemical Methane Reforming and Water Splitting for H2 and Syngas Production

Due to the continuous increase in the population of world and drastic depletion of the fossil fuel reservoirs, it is highly essential to invest towards renewable energy technologies such as solar energy (storage, conversion and utilization). A two-step solar thermochemical H₂O and/or CO₂ splitting process which utilizes metal oxide based redox reactions is one of the promising ways of producing solar fuels such as solar H₂ or renewable precursors for fuels such as solar syngas (a mixture of H₂ and CO). This process includes the endothermic reduction of metal oxides at elevated temperatures by releasing O₂ and oxidation of the reduced metal oxide by H₂O, by CO₂, or by the mixture of the two producing H₂, CO or syngas. One of the major limitations associated with the MO based cycles is the higher thermal reduction temperature. To solve this issue associated with the higher reduction temperatures, methane can be used as the reducing agent. In this investigation, thermodynamic analysis of the two-step iron oxide based solar thermochemical methane reforming and water-splitting process was investigated in two sections with the help of commercial thermodynamic software’s such as HSC Chemistry and FactSage. In the first section, the thermodynamic equilibrium compositions were determined as a function of temperature and other operating parameters at different experimental conditions. In the second section, the second law thermodynamic analysis of iron oxide based solar thermochemical methane reforming and water-splitting process was performed. Once the process flow diagram was set, effects of operating parameters on solar absorption efficiency of the solar reactor (η_abs), solar energy input to the solar reactor (Q_solar), rediation heat losses from the solar reactor (Q_re-rad), net energy absorbed in the solar reactor (Q_reactor-net), rates of entropy produced in the solar reactor (I_rr,reactor) and cooling unit (I_rr,cooling) were calculated and plotted. At the end, the solar-to-fuel conversion efficiency (η_{solar-to-fuel}) for this process was estimated and compared with the other thermochemical fuel production cycles.