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From Field to Forest... Fueling America.
Ethanol: greenhouse gas emissions
Gasoline is a complex mixture of dozens of chemicals, many of them toxic. In stark contrast to gasoline, ethanol is non-toxic, water soluble and quickly biodegradable. Ethanol also contains 35% oxygen. Adding oxygen to fuel results in more complete fuel combustion, thus reducing harmful emissions. For both of these reasons ethanol has been used to replace MTBE as an oxygenate additive in reformulated gasoline.
MTBE was banned in New York State in 2004, and 26 other states, because it is non-biodegradable, an animal carcinogen, potentially a human carcinogen, and has contaminated ground water nation-wide. Replacing MTBE with ethanol reduces emissions of air pollutants such as carbon dioxide, carbon monoxide and benzene, also a known carcinogen. Therefore, fuel ethanol has a positive impact on both water pollution and air pollution.
During the photosynthesis process both solar energy and atmospheric Carbon Dioxide (CO2) is captured in the corn grown on US farms. When the corn is fermented to ethanol the energy is captured in the ethanol and the CO2 is recycled back to the atmosphere. This is simply a continuous recycle loop for CO2.
According to the EPA, “For every BTU of gasoline which is replaced by corn ethanol, the total lifecycle greenhouse gas emissions that would have been produced from that BTU of gasoline would be reduced by 21.8 percent. These emissions account not only for CO2, but also methane and nitrous oxide.”
"Phase 2 of the General Motors / Argonne National Laboratory “Well-to-Wheels” life cycle analysis of vehicle propulsion systems and fuels released in May 2005 concluded that there is no better currently available way to address petroleum fuel use and carbon dioxide emissions concerns than by using renewable fuels such as ethanol. Hybrid and diesel propulsion systems can reduce CO2 by 20 to 30 percent. In comparison, E85 can reduce CO2 by 75 to 85 percent. Fuel cells using renewably produced hydrogen could reduce CO2 even further, but commercial availability may be decades away." (Source: Ethanol & Energy)
The addition of ethanol to gasoline greatly reduces carbon monoxide (CO) emissions, a contributor to harmful ozone, and subsequently smog formation. Recent real life data clearly “shows a consistent association between ethanol blending and reduced ozone pollution from air quality monitoring conducted in Wisconsin, California, New York and other states.” (Source: Clearing the Air with Ethanol)
Back to: Ethanol Facts and Fiction
Citations and References
- Investing in the Carbon Cycle
KL Process Design Group, LLC
- Greenhouse Gas Impacts of Expanded Renewable and Alternative Fuels Use
United States Environmental Protection Agency
Office of Transportation and Air Quality
EPA420-F-07-035
April 2007
- Updated Energy and Greenhouse Gas Emissions Results of Fuel Ethanol
Michael Wang
Center for Transportation Research Energy Systems Division
Argonne National Laboratory
The 15th International Symposium on Alcohol Fuels
San Diego, CA
September 26-28, 2005
- Ethanol & Energy
An Ethanol Across America White Paper
Gary A. Herwick
Transportation Fuels Consulting, Inc.
Fall 2005
- Clearing the Air with Ethanol
A review of the real world impact from fuels blended with ethanol.
Brett Hulsey, Better Environmental Solutions
Brooke Coleman, Renewable Energy Action Project (REAP)
March 2006
- Effects of Fuel Ethanol Use on Fuel-Cycle Energy and
Greenhouse Gas Emissions
Center for Transportation Research
Argonne National Laboratory Operated by The University of Chicago,
under Contract W-31-109-Eng-38, for the
United States Department of Energy
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