Solar thermochemical conversion of CO2 via erbium oxide based redox cycle

Investigation of the viability of the erbium oxide-based solar thermochemical CO2 splitting cycle is reported. This study aimed to explore the effect of partial thermal reduction (TR) of Er2O3 on the thermodynamic process parameters desirable to design a solar reactor system for the erbium oxide-based CO2 splitting (ErO-CS) cycle. First, the percentage TR of Er2O3 is estimated as a function of the TR temperature (TH). Acquired results indicated that to achieve a percentage TR of Er2O3 in the range of 5-100%; the solar reactor has to be functioned in the temperature range of TH = 2327-2677 K. The solar energy required to drive the ErO-CS cycle (Q?solar-cycle-ErO-CS) was observed to be on the higher side due to the obligation of the elevated values of TH. This rise in the Q?solar-cycle-ErO-CS as a function of percentage TR of Er2O3 reflected in a decrease in the solar-to-fuel energy conversion efficiency (eta solar-to-fuel-ErO-CS). The maximum eta solar-to-fuel-ErO-CS = 4.04% is achieved for a percentage TR of Er2O3 = 25% (TH = 2432 K). By employing 100% heat recuperation, the eta solar-to-fuel-ErO-CS (for percentage TR of Er2O3 = 25%) increased up to 5.79%. (c) 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.