An ethanol-powered PHEV would still require some fossil fuels to make fertilizer, pesticides, fungicides and diesel fuel used in farming, plus diesel fuel to bring the biomass to the ethanol plant, natural gas or coal to run the ethanol plant, and more diesel to transport the ethanol to the fueling station. Fossil fuel use would be substantially reduced with cellulosic ethanol production that would use the “stover” or corn stalks and roots left over after harvesting the corn.
 The computer also modeled biofuel powered ICVs and HEVs. However, the greenhouse gas reduction and oil reductions with these vehicles were always less than those of the biofuel powered PHEVs, so we only report the best case PHEVs here.
 Wang, MQ, “Greenhouse gases, regulated emissions, and energy use in transportation (GREET)”, Argonne National Laboratory.