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LIFE CYCLE BASED STUDIES ON BIOETHANOL FUEL FOR SUSTAINABLE TRANSPORTATION: A LITERATURE REVIEW
CURRAN, MARY ANN. LIFE CYCLE BASED STUDIES ON BIOETHANOL FUEL FOR SUSTAINABLE TRANSPORTATION: A LITERATURE REVIEW. Presented at SETAC ANNUAL FALL MEETING, BALTIMORE, MD, November 14 - 17, 2005.
To inform the public.
A literature search was conducted and revealed 45 publications (1996-2005) that compare bio-ethanol systems to conventional fuel on a life-cycle basis, or using life cycle assessment. Feedstocks, such as sugar beets, wheat, potato, sugar cane, and corn, have been investigated in many countries, including Brazil, Canada, India, the Philippines, South Africa, the United States and several European nations. Most work has been limited to energy and greenhouse gas assessments. Their focus has been to determine if the use of bio-mass to make fuel is a net energy loss or a net gain. A fairly consistent conclusion of the studies that calculated energy balances was that the use of bio-ethanol in place of conventional fuels or as an additive leads to a net gain. Six studies were found that evaluated other environmental impact categories beyond energy and greenhouse gases. Several looked specifically at the North American corn-to-ethanol route and reported very critical findings regarding environmental sustainability. Acidification, human toxicity and ecological toxicity impacts, mainly occurring during the harvesting and processing of the bio-mass, were more often unfavourable than favourable for bio-ethanol. Better data are needed for these impact categories, as well as for land use and its effects on biodiversity. Also, studies are needed to fill the critical gaps, especially on ethanol from tropical sugar crops, ethanol from cellulosic cropped feedstocks, particularly from perennial grasses, and corn to bio-ethanol in the United States. The findings of the literature review indicate that basing fuel production policy on environmental sustainability studies that are life cycle based but that ignore issues other than fossil fuel depletion and greenhouse gas emissions, are likely to result in unintended, and possibly detrimental, shifting of environmental burdens. Human and ecological health impacts need to be weighed into the decision-making process along with climate change and resource depletion concerns.