(720c) Solar Fuel Production Via GeO2/Geo Thermochemical H2O and CO2 Splitting Cycle

This investigation reports the computational thermodynamic analysis of the two-step GeO₂/GeO based solar thermochemical H₂O and/or CO₂ splitting process for the production of solar H₂, solar CO, or solar syngas. It is a two-step process in which the first step belongs to solar thermal reduction of GeO₂ into GeO and the second step corresponds to the thermochemical splitting of H₂O and/or CO₂ via the oxidation of GeO into GeO₂ and producing solar H₂, solar CO, or solar syngas. At first the equibrium thermodynamic compositions for the GeO₂/GeO based solar thermochemical H₂O and/or CO₂ splitting process were determined at different experimental conditions. Effects of thermal reduction and H₂O and/or CO₂ splitting temperatures, pressure, and inert gas flow rate on thermodynamic equilibrium compositions were 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. The second law thermodynamic analysis of GeO₂/GeO based solar thermochemical H₂O and/or CO₂ splitting redox system was also performed. Influence of thermal reduction and H₂O and/or CO₂ splitting temperatures and solar concentration ratio 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 cooling units were calculated and plotted. The solar-to-fuel conversion efficiency for the GeO₂/GeO based solar thermochemical H₂O and/or CO₂ splitting process was determined and effect of heat recuperation, thermal reduction and H₂O and/or CO₂ splitting temperatures and C on solar-to-fuel conversion efficiency was examined. The results obtained will be compared with the previously investigated solar thermochemical cycles.