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BIO-ETHANOL FUELS: SHORT-TERM SOLUTIONS, LONG-TERM DISASTERS
Citation:
CURRAN, MARY ANN. BIO-ETHANOL FUELS: SHORT-TERM SOLUTIONS, LONG-TERM DISASTERS. Presented at "VISIONS, CHALLENGES AND STEPS TOWARD SUSTAINABLE SOCIETIES" SYMPOSIUM, KNOXVILLE, TN, October 21, 2005.
Impact/Purpose:
To inform the public
Description:
Ethanol derived from bio-mass is often advocated as a significant contributor to possible solutions to our need for a sustainable transportation fuel. Substituting bio-ethanol for conventional fuel immediately addresses the issue of reducing our use of non-renewable resources (fossil fuels) and the attendant impacts on climate change, especially carbon dioxide and the resulting greenhouse effect, but it does not always address the notion of overall improvement. For instance, it is well-understood that the conversion of bio-mass to bio-energy requires additional energy inputs, most often provided in some form of fossil fuel. A recent literature search revealed 45 publications (1996-2005) that compare bio-ethanol systems to conventional fuel on a life-cycle basis, or using life cycle assessment. Most assessments of converting biomass to fuels are limited to energy and greenhouse gas (GHG) balances to determine if there is a net loss or gain. A fairly consistent conclusion of these studies is that the use of bio-ethanol in place of conventional fuels leads to a net gain. However, the findings of the literature review indicate that basing fuel production policy on environmental sustainability studies that are life cycle based but that ignore other issues 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. Acidification, human toxicity and ecological toxicity impacts, mainly occurring during the harvesting and processing of the bio-mass, were more often unfavorable than favorable for bio-ethanol. 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. Studies are needed to fill the critical gaps, especially on ethanol from tropical sugar crops, cellulosic cropped feedstocks, particularly perennial grasses, and corn. Moving toward sustainability requires a re-thinking of our systems of production, consumption and waste management and an increased awareness of the need to avoid shifting of problems, as often occurs with isolated measures. The ecological advantages should outnumber, or outweigh, the disadvantages to the environment and human health. Numerous studies have been done in recent years evaluating the life cycle impacts of bio-ethanol. However, while over 40 studies have been life cycle based, only six were identified which could be said to be life cycle assessments. These six studies do not, of course, cover the full range of possible feedstocks and geographies, and their results in the standard impact categories diverge. Future assessments should undertake evaluations of locations outside Europe and North America and pay more attention to the safeguard subjects of human and ecological health. Environmental sustainability studies that are life cycle based in the sense of extending from the crop to the wheel, but that ignore issues other than fossil fuel depletion and GHG emissions lead to limited results and are likely to result in detrimental shifting of burdens.