Life cycle assessment of optimised chemical looping air separation systems for electricity production

Abstract

Chemical looping air separation (CLAS) is as a very promising technology for the production of pure oxygen through the cyclic reduction and oxidation of a solid material at elevated temperatures. This study focused on the environmental potential of electricity and CO2 production through oxyfuel combustion of lignite. First, an attributional LCA assessed the operations which mainly contribute to the total environmental impacts for two different scenarios at the limits of the operating window (100% and 25% active material). Then, this study analysed the potential of electricity and pure CO2 production through CLAS when compared with conventional power production technologies from renewable and fossil alternatives, including electricity from hydro power, electricity from wind power, electricity from nuclear, electricity from photovoltaic, electricity from biogas, electricity from biomass, electricity from waste, electricity from hard coal and electricity from natural gas. Overall the results, analysed per MJ of electricity produced, showed how the chemical looping technology consistently performs better than the other technologies, especially thanks to the recovery of the pure CO2 stream used for industrial purposes, which avoids the production of CO2 from fossil resources. However, the cleaning of the flue gas of the oxyfuel combusted lignite strongly limits the toxicities indicators.