Assessing environmental externalities of transportation fuels
The purpose of this study was to estimate the environmental externalities associated with various transportation fuels in the United States. We used GREET—a life-cycle analysis model; FASOM-GHG—a partial equilibrium dynamic optimization model on agriculture and forestry; APEEP—an integrated assessment model to calculate the marginal damage of emissions; the GTAP-BIO model—a computable general equilibrium model to estimate global land use and land cover changes due to biofuels policies; and the OSIRIS model to estimate the species extinctions based on deforestation due to biofuels policy scenario results. The FASOM-GHG- and GREET-based analysis on incorporating regional variation in crop yields and inputs did not reveal any significant variation in ethanol-based GHG emissions across the regions. The GTAP-BIO model-based global deforestation rates due to implementation of US Renewable Fuels Standard (RFS2) policies for first-generation biofuels, when applied to the OSIRIS model, indicated insignificant loss in biodiversity. These estimations would help in understanding whether a particular transportation fuel technology is environmentally sustainable and benefits the economy.