Switchgrass Biomass to Liquid Transportation Fuels: Modeling of a Biological Conversion Process

Abstract

A computational model for biological conversion of biomass to liquid transportation fuels is introduced to a pre-existing thermochemical process superstructure. The model was developed from experimental work done by Professor Mark Holtzapple’s group on a biological pathway called the MixAlco process. Switchgrass biomass is fermented to produce carboxylate acids, which are then converted to ketones, secondary alcohols, and finally hydrocarbons within the range of gasoline, diesel, and kerosene liquid fuels. Four different cases, two each of biological and thermochemical processes at different capacities, were compared. The thermochemical process is overall more efficient and less expensive than the biological process, but the calculated break-even oil price (BEOP) shows that biological production of fuels can be competitive with traditional petroleum-based processes.