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International Journal of Photoenergy
Volume 2016, Article ID 9727895, 9 pages
http://dx.doi.org/10.1155/2016/9727895
Research Article

Solar Thermochemical Hydrogen Production via Terbium Oxide Based Redox Reactions

Department of Chemical Engineering, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar

Received 24 November 2015; Revised 16 December 2015; Accepted 5 January 2016

Academic Editor: Juan M. Coronado

Copyright © 2016 Rahul Bhosale et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The computational thermodynamic modeling of the terbium oxide based two-step solar thermochemical water splitting (Tb-WS) cycle is reported. The 1st step of the Tb-WS cycle involves thermal reduction of TbO2 into Tb and O2, whereas the 2nd step corresponds to the production of H2 through Tb oxidation by water splitting reaction. Equilibrium compositions associated with the thermal reduction and water splitting steps were determined via HSC simulations. Influence of oxygen partial pressure in the inert gas on thermal reduction of TbO2 and effect of water splitting temperature () on Gibbs free energy related to the H2 production step were examined in detail. The cycle () and solar-to-fuel energy conversion () efficiency of the Tb-WS cycle were determined by performing the second-law thermodynamic analysis. Results obtained indicate that and increase with the decrease in oxygen partial pressure in the inert flushing gas and thermal reduction temperature (). It was also realized that the recuperation of the heat released by the water splitting reactor and quench unit further enhances the solar reactor efficiency. At  K, by applying 60% heat recuperation, maximum of 39.0% and of 47.1% for the Tb-WS cycle can be attained.