Solar thermochemical conversion of CO 2 via erbium oxide based redox cycle

Investigation of the viability of the erbium oxide‐based solar thermochemical CO 2 splitting cycle is reported. This study aimed to explore the effect of partial thermal reduction (TR) of Er 2 O 3 on the thermodynamic process parameters desirable to design a solar reactor system for the erbium oxide‐based CO 2 splitting (ErO‐CS) cycle. First, the percentage TR of Er 2 O 3 is estimated as a function of the TR temperature ( T H ). Acquired results indicated that to achieve a percentage TR of Er 2 O 3 in the range of 5–100%; the solar reactor has to be functioned in the temperature range of T H = 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 T H . This rise in theQ ̇solar-cycle-ErO-CSas a function of percentage TR of Er 2 O 3 reflected in a decrease in the solar‐to‐fuel energy conversion efficiency (ηsolar-to-fuel-ErO-CS). The maximumηsolar-to-fuel-ErO-CS= 4.04% is achieved for a percentage TR of Er 2 O 3 = 25% ( T H = 2432 K). By employing 100% heat recuperation, theηsolar-to-fuel-ErO-CS(for percentage TR of Er 2 O 3 = 25%) increased up to 5.79%. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.