Environmental Impacts of Bioethanol, Chapter 5

Two in-depth, peer-reviewed studies that compare certain environmental impacts of biomass ethanol and gasoline used as neat fuels on a fuel cycle basis have been completed. The best known and most cited is the work done by M. A. DeLuchi entitled 'Emissions of Greenhouse Gases from the Use of Transportation Fuels and Electricity' {1,2}. The second was conducted by an interlaboratory (IL) groupthat comprises the National Renewable Energy Laboratory, Oak Ridge National Laboratory, and the Pacific Northwest Laboratory entitled 'Fuel Cycle Evaluations of Biomass-Ethanol and Reformulated Gasoline [3a,3b]. The IL study investigated a host of air emissions and wastes (liquid and solid) from two fuel cycles. This chapter will describe the results of these two studies. Substituting biomassethanol for reformulated gasoline in hight-duty vehicles has substantial environmental benefits. Greenhouse gas emissions are best characterized by the DeLuchi study, which found a reduction of approximately 2.2 million t of carbon dioxide equivalents per 1 billion L of ethanol. The IL estimated substantial overall reductions in other emissions - 1218 t of sulfur dioxide and 695 t of oxides ofnitrogen emissions per 1 billion L of E95. Although total liquid and solid effluents were estimated to increase, their hazardous and toxic natures were eliminated.