9-07: Biomass-to-wheel efficiency analysis suggests that increasing biomass conversion efficiency would achieve transportation fuel independence

Analysis of energy efficiency for different biomass-utilization scenarios would help guide future directions of advanced transportation systems.  We conducted the simplified life cycle analysis by considering efficiencies of three elements -- biomass-to-fuel conversions, fuel transport and distribution means, and their respective powertrain systems.   Diverse biofuels produced from lignocellulosic biomass include cellulosic ethanol, butanol, fatty acid ethyl esters (microdiesel), methane, hydrogen, methanol, dimethyether, Fischer-Tropsch diesel, and bioelectricity; the respective power train systems include internal combustion engine (ICE), hybrid electric vehicle (HEV) based on gasoline ICE or diesel ICE, hydrogen fuel cell vehicle (FCV), sugar fuel cell vehicle (SFCV), and battery electric vehicle (BEV).  Up to 14 scenarios were analyzed based on the biomass-to-wheel (BTW) efficiency, representing a conversion of chemical energy in the delivered biomass to kinetic energy on wheels.  Our analysis suggests that BEV where electricity is generated through fuel cells and SFCV where sugar as a hydrogen carrier is converted to hydrogen on-board would have the highest BTW efficiencies, nearly four times of that of ethanol-ICE.  But SFCV may have advantages in higher energy density, faster refilling rates, and less environmental burden than BEV.  We concluded that one billion of biomass would be sufficient to replace crude oil completely if we greatly increase biomass utilization efficiency.