The fowllowing is an excerpt from Sustainable Ethanol: Biofuels, Biorefineries, Cellulosic Biomass, Flex-Fuel Vehicles, and Sustainable Farming for Energy Independence
An energy system is unsustainable if it destroys our ecosystem. Experts often disagree about environmental impacts, perhaps because they are looking at different aspects of the issue. An examination of a broad range of issues shows that ethanol fuel is neither the one perfect solution (there is no such thing) nor a dead end. (continued below)
Measuring Environmental Impact
Practically any human activity impacts the environment in some way. Making and using ethanol is no exception. Ethanol can be considered beneficial if it does less damage than the fuel it replaces. Ethanol primarily replaces petroleum-derived gasoline in today’s North American transportation system. When we consider ethanol’s environmental impact, we must do so in comparison to gasoline. We need to begin with some assumptions established elsewhere in this book:
1. Over time, fossil fuel prices will probably remain high (see Chapter 2).
2. Ethanol enjoys a better net energy balance than gasoline (see Chapter 10).
High fossil fuel prices will affect the way we grow and refine ethanol feedstocks for the better. The increasing cost of fossil fuel-based herbicides, fertilizers, and process fuels creates a market force to minimize their use. The resulting improvement in energy balance and decrease in harmful chemical use will lessen environmental damage from ethanol.
Most scientists believe we derive more energy value from the use of ethanol than could be derived from the fossil fuels used in its production. Of thirteen major studies on the subject completed between 1998 and 2005, nine showed a positive energy balance for corn ethanol.[i] Ethanol may perform better than the energy balance studies indicate. They generally assume a lower fuel economy for ethanol based on its lower energy content. However, some car models already on North American roads actually suffer little or no loss in fuel economy on E10 (10% ethanol).[ii]
The numbers look even better for ethanol’s energy balance when compared to gasoline. Gasoline has a decidedly negative energy balance because of the fossil fuels required for extracting, transporting, and refining crude oil. The University of Chicago’s Argonne National Laboratory estimates gasoline has a negative 25% energy balance, while corn ethanol enjoys a positive energy balance of more than 25%.[iii] Ethanol’s energy balance has steadily improved over the years.[iv] This trend means less fossil fuel use and less environmental impact related to emissions, chemical contamination, and global warming. On the other hand, technology for refining gasoline is older and less likely to show as much improvement in efficiency.
See chapter 4 of Sustainable Ethanol for the following additional topics:
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[i]. Michael Wang, “The Debate on Energy and Greenhouse Gas Emissions Impacts of Fuel Ethanol” University of Chicago Argonne National Laboratory, 2005, 24.
[ii]. KT Knapp, FD Stump, & SB Tejada, “The Effect of Fuel on the Emissions of Vehicles over a Wide Range of Temperatures,” Journal of the Air & Waste Management Association 43 (July 1998); American Coalition for Ethanol, Fuel Economy Study, 2005, http://www.ethanol.org/documents/ACEFuelEconomyStudy.pdf.
[iii]. Wang, “The Debate on Energy,” 23.
[iv]. Ibid., 24.