This thesis evaluates selected environmental implications resulting from ethanol produced from cellulosic feedstocks and its use in light-duty vehicles. Modifications are made to a life cycle-based model (GREET). These modifications include; revising the model default values on soil carbon change due to land use change, and N2O emissions from soils and agricultural activities associated with switchgrass production. Additionally a module for corn stover-derived ethanol was developed. The analyses show that production of switchgrass in different regions and on different types of land could impact the potential of switchgrass-derived ethanol for reducing greenhouse gas (GHG) emissions. It is found that N2O emissions from soils are a major source of GHG emissions in the life cycle of switchgrass-derived ethanol. Finally, the production and use of corn stover-derived ethanol as E85 in a light-duty vehicle could reduce fossil fuel use by 94% and GHG emissions by 87%, compared to a vehicle fueled with reformulated gasoline.