Tank to Wheel Emissions of Ethanol and Biodiesel Powered Vehicles as Compared to Petroleum Alternatives

Air quality modeling of the air pollution effects of alternative fuels must be supported with data on the tailpipe emissions of those fuels relative to conventional fuels. Here a literature review is presented of the tailpipe and evaporative emissions from 85% ethanol (E85), 10% ethanol (E10), and 20% biodiesel (BD20) compared to conventional fuels. It is found that E85 causes both positive and negative changes in emissions relative to gasoline, depending on the pollutant, and the changes in some pollutants have an uncertain sign. E10 and BD20 in general exhibit smaller changes in emissions compared to E85, the impacts of which cannot be fully known without air quality modeling.