A Comparison of the Full Costs of Ethanol and Gasoline

Many alternative transportation fuels are technologically feasible, but whether they are desirable replacements for petroleum from a societal standpoint requires that their full cost of production and use be considered, including both direct and external costs. Here the life-cycle climate change and health effects of greenhouse gas (GHG) and fine particulate matter (PM2.5) emissions from gasoline, corn ethanol, and cellulosic ethanol are quantified and monetized. Considered are multiple biorefinery heat and power sources (natural gas, corn stover, and coal), technology improvements in corn ethanol production, and multiple feedstocks for cellulosic ethanol (prairie biomass, Miscanthus, corn stover, and switchgrass). The development of a geographically-explicit spatial life cycle assessment (LCA) to estimate the human health impact of PM2.5 is also described. External air pollution costs are then compared to direct production costs, accounting for variability in input prices as experienced in a growing biofuels industry. The importance of drawing such comparisons in driving energy policy toward sustainable alternatives is emphasized.