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Laboratory Production of Biofuels and Biochemicals from a Rapeseed Oil through Catalytic Cracking Conversion
Published on: September 2, 2016
Replacing gasoline with corn ethanol results in significant environmental problem-shifting
Yi Yang1, Junghan Bae, Junbeum Kim
1Bren School of Environmental Science and Management, University of California, Santa Barbara, California 93106-5131, United States.
Environmental Science & Technology
|March 7, 2012
Summary
Corn ethanol (E85) does not outperform gasoline across multiple environmental impacts. Corn production for E85 leads to greater eutrophication and water scarcity, suggesting a need to re-evaluate energy policies.
Area of Science:
- Environmental Science
- Agricultural Engineering
- Energy Policy
Background:
- Previous life-cycle assessments of corn ethanol primarily focused on greenhouse gas (GHG) emissions and energy balance.
- Regional variations in agricultural practices and a broader range of environmental impacts were largely unexamined.
- Corn ethanol is promoted as a renewable alternative to gasoline, often based on limited environmental metrics.
Purpose of the Study:
- To compare the comprehensive environmental impacts of corn ethanol (E85) versus gasoline, considering regional agricultural differences.
- To evaluate 12 distinct environmental impact categories, moving beyond solely GHG emissions.
- To inform policy decisions by providing a more holistic environmental assessment of biofuels.
Main Methods:
- Life-cycle assessment comparing gasoline and E85.
- Inclusion of regional agricultural practices across 19 corn-growing states.
- Evaluation of 12 environmental impact categories, including eutrophication and water scarcity.
- Impact aggregation using National Institute of Standards and Technology (NIST) weighting factors.
- Consideration of indirect land use change (iLUC) GHG emissions.
Main Results:
- E85 does not consistently outperform gasoline when a wide spectrum of environmental impacts is considered.
- Aggregated impacts show E85 generating 6%–108% (23% average) greater environmental impact than gasoline, driven by corn production's eutrophication and irrigation demands.
- Including iLUC GHG emissions widens the gap, with E85 showing 16%–118% (33% average) greater impact.
Conclusions:
- Replacing gasoline with corn ethanol may shift environmental burdens towards increased eutrophication and water scarcity.
- Current environmental criteria, such as those in the Energy Independence and Security Act (EISA), may need re-evaluation.
- Policy assessments should incorporate a broader range of environmental impacts beyond GHG emissions for accurate biofuel evaluations.
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