Woody biomass-based transportation fuels - A comparative techno-economic study

Production of synthetic vehicle fuels from biomass is a hot topic. There are several alternative fuels to consider when evaluating properties such as cost of production and energy efficiency to both product and final use in a road vehicle. Thermochemical conversion via gasification and downstream synthesis of fuels as well as biochemical conversion of woody biomass to ethanol is considered in this paper. The vehicle fuels considered in this paper include methanol, ethanol, synthetic natural gas, Fischer-Tropsch diesel, dimethyl ether and synthetic gasoline from the methanol-to-gasoline process. The aim of the study is to evaluate all the different fuels on the same basis. The production cost of the various fuels is estimated as well as the overall investment cost. Well-to-wheel energy efficiency calculations were performed to evaluate how far a vehicle can travel on the fuel produced from a specific amount of feedstock. The production cost of the fuel as a function of distance travelled is also presented. Of the fuels considered in this study, dimethyl ether manages the highest efficiency from feedstock to travelled distance and manages to do so at the lowest cost. Ethanol produced from woody biomass is the most inefficient and expensive fuel, when considering biomass harvesting and transport, the production and road use (ignoring fuel distribution), in this study due to low yields in fuel production. Total investment cost for ethanol is considerably lower at MM$ 281 compared to the thermochemical fuels that ranges from MM$ 580 to MM$ 760. The production costs of the various fuels range from $79.9/MW h for synthetic natural gas to 139.6 $/MW h for Fischer-Tropsch diesel. The production cost translates to a travel cost ranging from $4.98/100 km for dimethyl ether to $8.51/100 km for ethanol.