Solar hydrogen production via ZnO/Zn based thermochemical water splitting cycle: Effect of partial reduction of ZnO

This investigation reports the examination of the influence of partial reduction of ZnO on the thermodynamic parameters allied with the ZnO/Zn WS cycle. The efficiency analysis was conducted by developing and following the ZnO/Zn process flow configuration. By estimating the equilibrium compositions, the percentage of ZnO reduction (ZnO-R) as a function of the thermal reduction (TR) temperature (T-H) was determined. After identifying the ZnO-R percentages, the influence T-H of and ZnO-R on the thermodynamic process parameters was explored. Overall results of the efficiency analysis indicate that the operation of the partially reduced ZnO/Zn WS cycle, in the temperature range of 1040 K-1240 K, was more useful rather than operating at 1340 K. ZnO-R equal to 57.2% (T-H = 1240 K) was favorable to operate the ZnO/Zn WS cycle as a further rise in the ZnO-R did not yield any significant improvement in the solar-to-fuel energy conversion efficiency. At ZnO-R equal to 57.2% (T-H = 1240 K), by applying 50% HR, a value of 62.6% as the efficiency of solar to fuel can be achieved. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the influence of partial reduction of ZnO on the thermodynamic parameters of the ZnO/Zn WS cycle. Results indicate that operating the partially reduced ZnO/Zn WS cycle in the temperature range of 1040 K-1240 K is more efficient.