(398d) Chemical Looping Strategy and Its Novel, Exergetically Optimized Applications in Fossil Energy Conversions

Through the assistance of an oxygen carrier particle, the chemical looping gasification strategy indirectly converts fossil and biomass fuels into carbon free energy carriers such as hydrogen and/or electricity with 100% CO₂ capture. Besides serving as a stand alone process, the looping strategy can be integrated with other energy conversion systems to minimize the exergy loss of the overall process. In this paper, the developmental status of the Coal/Biomass Direct Chemical Looping (CDCL) gasification process, which is being tested at 25 kW_th scale at the Ohio State University for co-production of hydrogen and electricity, is briefly reviewed. Several novel, exergetically optimized CDCL configurations that convert coal and biomass into liquid fuel, electricity and/or hydrogen with ultra-high energy conversion efficiencies, are presented and analyzed. The analysis results indicate that, through the utilization of chemical looping strategy, the irreversibility of the fuel conversion process can be reduced, resulting in significantly improved energy and exergy conversion efficiencies. Life cycle analysis (LCA) indicates that, when biomass is used as the feedstock, the overall CO₂ emission from the chemical looping gasification process can be negative.