Thermodynamic study on solar thermochemical fuel production with oxygen permeation membrane reactors

Thermodynamic analysis is performed on a conceptual oxygen permeation membrane reactor driven by concentrated solar energy (heat) for isothermal H2O splitting for the purpose of solar fuel derivation. By way of a plug-flow reactor model, kinetic and thermodynamic factors responsible for conversion rate, reactor dimension, and solar-to-fuel efficiency are analyzed for the case of pump-assisted and methane-assisted scenarios. The pump-assisted case achieves the same solar-to-fuel efficiency (2.9% at 1500 degrees C) as isothermal solar thermochemical cycling, while the methane-assisted case attains much higher efficiencies at much lower temperatures, whose net solar-to-fuel efficiency reaches 63% at around 900 degrees C. The theoretical framework developed in this study can be applied to the solar thermochemical splitting of other gases such as CO2 and can be further extended to the co-splitting of H2O and CO2 for syngas production driven by solar energy only (i.e., without the participation of hydrocarbon fuels). Copyright (c) 2015 John Wiley & Sons, Ltd.