1
&EPA
EPA/600/R-10/183F | December 2011 | www.epa.gov
United States
Environmental Protection
Agency
Biofuels and the Environment:
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First Triennial Report to Congress
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EPA/600/R-10/183F
December 2011
Biofuels and the Environment:
First Triennial Report to Congress
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC
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DISCLAIMER
This document has been reviewed in accordance with U.S. Environmental Protection
Agency policy and approved for publication. Mention of trade names or commercial products
does not constitute endorsement or recommendation of use.
ABSTRACT
This is the first triennial Report to Congress required under Section 204 of the 2007
Energy Independence and Security Act (EISA). EISA increases the renewable fuel standards
(RFS) to 36 billion gallons per year by 2022. Section 204 requires an assessment of
environmental and resource conservation impacts of the RFS program. Air and water quality,
soil quality and conservation, water availability, ecosystem health and biodiversity, invasive
species, and international impacts are assessed, as well as opportunities to mitigate these impacts.
Feedstocks compared include corn starch, soybeans, corn stover, perennial grasses, woody
biomass, algae, and waste. Biofuels compared include conventional and cellulosic ethanol and
biodiesel. This report is a qualitative assessment of peer-reviewed literature.
This report concludes that (1) the extent of negative impacts to date are limited in
magnitude and are primarily associated with the intensification of corn production; (2) whether
future impacts are positive or negative will be determined by the choice of feedstock, land use
change, cultivation and conservation practices; and (3) realizing potential benefits will require
implementation and monitoring of conservation and best management practices, improvements
in production efficiency, and implementation of innovative technologies at commercial scales.
This report provides a foundation for comprehensive environmental assessments of biofuel
production.
For sale by the Superintendent of Documents, U.S. Government Printing Office
Internet: bookstore.gpo.gov Phone: toll free (866) 512-1800; DC area (202) 512-1800
Fax: (202) 512-2104 Mail: Stop IDCC, Washington, DC 20402-0001
ISBN 978-0-16-090612-1
Preferred citation: U.S. Environmental Protection Agency. 2011. Biofuels and the
Environment: First Triennial Report to Congress. Office of Research and Development, National
Center for Environmental Assessment, Washington, DC; EPA/600/R-10/183F. Available online
at http://epa.gov/ncea.
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TABLE OF CONTENTS
EXECUTIVE SUMMARY xiv
1. INTRODUCTION 1-1
1.1. Organization of This Report 1-3
2. BACKGROUND AND APPROACH 2-1
2.1. EISA andRFS2 Requirements for Biofuel Production and Use 2-1
2.1.1. Life Cycle Greenhouse Gas Thresholds 2-2
2.1.2. Life Cycle Assessment and Environmental Impacts 2-3
2.1.3. Projected Fuel and Feedstock Use to Meet Required RFS2 Targets
through 2022 2-4
2.2. Regulatory Authority Relevant to Biofuel Environmental Impacts 2-6
2.3. Approach to the Section 204 Report 2-7
2.3.1. Qualitative Synthesis of the Literature Reviewed for This Report 2-7
2.3.2. Biofuel Production Stages Discussed in This Report 2-8
2.3.3. Feedstocks and Fuels Discussed in This Report 2-9
2.3.4. Impacts Discussed in This Report 2-9
3. ENVIRONMENTAL IMPACTS OF SPECIFIC FEEDSTOCKS 3-1
3.1. Introduction 3-1
3.2. Row Crops (Corn, Corn Stover, Soybeans) 3-3
3.2.1. Introduction 3-3
3.2.2. Overview of Environmental Impacts 3-3
3.2.3. Current and Projected Cultivation 3-5
3.2.4. Water Quality 3-9
3.2.5. Water Quantity 3-17
3.2.6. Soil Quality 3-21
3.2.7. Air Quality 3-23
3.2.8. Ecosystem Impacts 3-25
3.2.9. Key Findings 3-28
3.3. Perennial Grasses 3-31
3.3.1. Introduction 3-31
3.3.2. Overview of Environmental Impacts 3-33
3.3.3. Current and Projected Cultivation 3-33
3.3.4. Water Quality 3-34
3.3.5. Water Quantity 3-38
3.3.6. Soil Quality 3-39
3.3.7. Air Quality 3-40
3.3.8. Ecosystem Impacts 3-41
3.3.9. Key Findings 3-45
3.4. Woody Biomass 3-47
3.4.1. Introduction 3-47
3.4.2. Overview of Environmental Impacts 3-48
3.4.3. Current and Projected Product!on Areas 3-48
3.4.4. Water Quality 3-49
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TABLE OF CONTENTS (CONTINUED)
3.4.5. Water Quantity 3-51
3.4.6. Soil Quality 3-52
3.4.7. Air Quality 3-53
3.4.8. Ecosystem Impacts 3-54
3.4.9. Key Findings 3-56
3.5. Algae 3-57
3.5.1. Introduction 3-57
3.5.2. Overview of Environmental Impacts 3-59
3.5.3. Current and Projected Cultivation 3-59
3.5.4. Water Quality 3-60
3.5.5. Water Quantity 3-60
3.5.6. Soil Quality 3-61
3.5.7. Air Quality 3-61
3.5.8. Ecosystem Impacts 3-61
3.5.9. Key Findings 3-62
3.6. Waste-Based Feedstocks 3-63
3.6.1. Introduction 3-63
3.6.2. Municipal Solid Waste 3-64
3.6.3. Other Wastes 3-64
3.6.4. Environmental Impacts of Waste-Based Biofuel 3-65
3.7. Summary of Feedstock-Dependent Impacts on Specialized Habitats 3-65
3.7.1. Forests 3-66
3.7.2. Grasslands 3-66
3.7.3. Impacts on Wetlands 3-67
3.8. Genetically Engineered Feedstocks 3-68
4. BIOFUEL PRODUCTION, TRANSPORT, STORAGE, AND END USE 4-1
4.1. Introduction 4-1
4.2. Feedstock Logistics 4-2
4.2.1. Handling, Storage, and Transport 4-2
4.3. Biofuel Production 4-2
4.3.1. Biofuel Conversion Processes 4-2
4.3.2. Air Quality 4-4
4.3.3. Water Quality and Availability 4-6
4.3.4. Impacts from Solid Waste Generation 4-10
4.4. Biofuel Distribution 4-11
4.4.1. Air Quality 4-11
4.4.2. Water Quality 4-12
4.5. Biofuel End Use 4-14
4.5.1. Air Quality 4-14
5. INTERNATIONAL CONSIDERATIONS 5-1
5.1. Introduction 5-1
5.2. Import/Export Volumes 5-3
5.3. Environmental Impacts of Direct and Indirect Land Use Changes 5-6
IV
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TABLE OF CONTENTS (CONTINUED)
5.4. Other Environmental Impacts 5-11
5.5. Conclusions about International Impacts 5-12
6. SYNTHESIS, CONCLUSIONS, AND RECOMMENDATIONS 6-1
6.1. Introduction 6-1
6.2. Assessment Scenarios 6-1
6.2.1. Assumptions Underlying the Synthesis of Feedstock Production
Impacts 6-1
6.2.2. Assumptions Underlying the Synthesis of Biofuel Production,
Transport, and Storage Impacts 6-2
6.3. Synthesis 6-2
6.3.1. Feedstock Production 6-4
6.3.2. Biofuel Production, Transport, and Storage 6-8
6.3.3. End-Use 6-9
6.4. Conclusions 6-10
6.5. International Considerations 6-11
6.6. Recommendations 6-12
6.6.1. Comprehensive Environmental Assessment 6-12
6.6.2. Coordinated Research 6-12
6.6.3. Mitigation of Impacts from Feedstock Production 6-13
6.6.4. International Cooperation to Implement Sustainable Biofuel
Practices 6-13
7. ASSESSING ENVIRONMENTAL IMP ACTS FROM BIOFUELS: 2013 TO 2022 7-1
7.1. Introduction 7-1
7.2. Components of the Second Assessment 7-1
7.2.1. Life Cycle Assessments 7-2
7.2.2. Environmental Risk Assessment 7-2
7.2.3. Human Health Assessment 7-3
7.2.4. Conceptual Models 7-3
7.2.5. Monitoring, Measures, and Indicators 7-3
7.2.6. Scenarios 7-4
7.2.7. Other Components 7-7
8. REFERENCES 8-1
APPENDIX A GLOSSARY AND ACRONYMS A-l
APPENDIX B SUMMARY OF EPA STATUTORY AUTHORITIES HAVING POTENTIAL IMPACT
ON THE PRODUCTION AND USE OF BIOFUELS B-l
APPENDIX C CONCEPTUAL MODELS C-l
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LIST OF TABLES
Table 2-1: RFS2 Renewable Fuel Requirements (Billion Gallons per Year) 2-2
Table 2-2: Life Cycle GHG Thresholds Specified in EISA (Percent Reduction from
2005 Baseline) 2-3
Table 3-1: Primary Fuels and Feedstocks Discussed in This Report 3-2
Table 3-2: 2009 Summary of Inputs to U.S. Biodiesel Production 3-7
Table 3-3: Example Comparison of Agricultural Intensity Metrics for Perennial
Grass, Short-Rotation Woody Crops and Conventional Crops 3-35
Table 3-4: Overview of Impacts on Forests from Different Types of Biofuel
Feedstocks 3-66
Table 3-5: Overview of Impacts on Grasslands from Different Types of Biofuel
Feedstocks 3-67
Table 3-6: Overview of Impacts on Wetlands from Different Types of Biofuel
Feedstocks 3-68
Table 5-1: Top Fuel Ethanol-Producing Countries from 2005 to 2009 (All Figures
Are in Millions of Gallons) 5-2
Table 5-2: 2008-2009 Brazilian Ethanol Exports by Country of Destination 5-5
Table 5-3: 2008 U.S. Biodiesel Balance of Trade 5-6
Table 5-4: Increases in International Crop Area Harvested by Renewable Fuel
Anticipated to Result from EISA Requirements by 2022 5-8
Table 6-1: Assumptions Underlying the Synthesis of Feedstock Production Impacts 6-3
Table 6-2: Assumptions Underlying the Synthesis of Biofuel Production, Transport
and Storage Impacts 6-4
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on
the Production and Use of Biofuels B-2
VI
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LIST OF FIGURES
Figure 2-1: Renewable Fuel Volumes to Meet RFS2 Targets 2-5
Figure 2-2: Five Stages of the Biofuel Supply Chain 2-8
Figure 2-3: Environmental and Resource Conservation Issues Addressed in This
Report 2-10
Figure 3-1: U.S. Acres of Crops Planted and U.S. Acres Enrolled in the CRP 3-3
Figure 3-2: U.S. Corn and Soybean Yield 3-4
Figure 3-3: Percent of Corn Grain Allocated to Ethanol for Fuel 3-5
Figure 3-4: Planted Corn Acres by County 3-6
Figure 3-5: Planted Soybean Acres by County 3-8
Figure 3-6: Change in Number of U.S. Coastal Areas Experiencing Hypoxia from
1960 to 2008 3-12
Figure 3-7: Generalized Map of Potential Rain-Fed Feedstock Crops in the
Conterminous United States Based on Field Plots and Soil, Prevailing
Temperature, and Rainfall Patterns 3-34
Figure 3-8: Estimated Forest Residues by County 3-49
Figure 4-1: Biofuel Supply Chain and Use of Biofuel 4-1
Figure 5-1: International Production of Biofuels 5-2
Figure 5-2: Annual U.S. Domestic Ethanol Production and Imports Volumes Reported
(2002 to 2009) and Projected (2011 to 2022) 5-4
Figure 5-3: Historic U.S. Ethanol Export Volumes and Destinations 5-6
Figure 5-4: Change in U.S. Exports by Crop Anticipated to Result from EISA
Requirements by 2022 5-8
Figure 5-5: International Land Use Change GHG Emissions Projected to Result from
EISA Requirements by 2022 5-9
Figure 5-6: Harvested Crop Area Changes Projected to Result from EISA
Requirements by 2022 5-10
Figure 5-7: Modeling of Pasture Area Changes in Brazil Anticipated to Result from
EISA Requirements by 2022 5-11
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LIST OF FIGURES (CONTINUED)
Figure 6-1: Most Positive, Negative, and Plausible Environmental Impacts (on a Per
Unit Area Basis) from Feedstock Production 6-6
Figure 7-1: Conceptual Diagram of the Potential Environmental Impacts of Biofuel
Feedstock Production 7-5
Figure 7-2: Conceptual Diagram of the Potential Environmental Impacts of Biofuel
Production and Use 7-6
Figure C-l: Pathways for Potential Environmental Impacts of Corn Starch Feedstock
Cultivation C-4
Figure C-2: Pathways for Potential Environmental Impacts of Soybean Feedstock
Cultivation C-5
Figure C-3: Pathways for Potential Environmental Impacts of Corn Stover Feedstock
Cultivation C-6
Figure C-4: Pathways for Potential Environmental Impacts of Perennial Grass
Feedstock Cultivation C-7
Figure C-5: Pathways for Potential Environmental Impacts of Short-Rotation Woody
Crop Feedstock Cultivation C-8
Figure C-6: Pathways for Potential Environmental Impacts of Forest Thinning and
Residue Removal C-9
Figure C-7: Potential Environmental Impacts of Algae Feedstock Production C-10
Figure C-8: Potential Environmental Impacts of Producing and Distributing
Conventional and Cellulosic Ethanol (Impacts of Fuel Use Not Included) C-l 1
Figure C-9: Potential Environmental Impacts of Producing and Distributing Biodiesel
(Impacts of Fuel Use Not Included) C-12
Vlll
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PREFACE
In December 2007, Congress enacted Public Law 110-140, the Energy Independence and
Security Act (EISA), to reduce U.S. energy consumption and dependence on foreign oil, and to
address climate change through research and implementation of strategies to reduce greenhouse
gases. In accordance with these goals, EISA required the U.S. Environmental Protection Agency
(EPA) to revise the Renewable Fuel Standard (RFS) program, created under the 2005 Energy
Policy Act, to increase the volume of renewable fuel required to be blended into transportation
fuel from 9 billion gallons per year in 2008 to 36 billion gallons per year by 2022. Additionally,
the U.S. Congress requested a report every three years (Section 204 of EISA) on the
environmental and resource conservation impacts of the RFS program. Specifically, EISA
requires the EPA Administrator, in consultation with the Secretary of Agriculture and the
Secretary of Energy, to assess and report to Congress on present and likely future impacts on
environmental issues, including air quality, effects on hypoxia, pesticides, sediment, nutrient and
pathogen levels in waters, acreage and function of waters, and soil environmental quality; on
resource conservation issues, including soil conservation, water availability, and ecosystem
health and biodiversity, including impacts on forests, grasslands, and wetlands; and on the
growth and use of cultivated invasive or noxious plants and their impacts on the environment and
agriculture.
This report is the first of EPA's triennial reports on the current and potential future
environmental impacts associated with the requirements of Section 21 l(o) of the Clean Air Act.
It reviews environmental and resource conservation impacts, as well as opportunities to mitigate
these impacts, at each stage of the biofuel supply chain: feedstock production, feedstock
logistics, biofuel production, biofuel distribution, and biofuel use. The information included here
is considered foundational for future efforts to quantitatively compare the environmental impacts
of alternative scenarios for meeting the goals of the RFS2 program. This first triennial report
represents the best available information through July 2010 and reflects the current
understanding about biofuel production and use, including input from the U.S. Departments of
Agriculture and Energy, with whom EPA consulted during development of this report.
An external review draft of this report was publicly released and comments solicited
through a Federal Register notice published on January 28, 2011 (FRL-9259-5; Docket ID No.
EPA-HQ-ORD-2010-1077). At a public peer review panel meeting on March 14, 2011, peer
reviewers summarized their comments on the review draft. Oral and written comments from the
public were also received at the March meeting. The external peer review and input from the
public resulted in approximately 1,800 separate comments. This final report reflects EPA's
careful evaluation and consideration of these comments as well as a final review by the Office of
Management and Budget. Future reports will reflect the evolving understanding of biofuel
impacts in light of new research results and data as they become available. This initial report to
Congress serves as a starting point for future assessments and for taking action to achieve the
goals of EISA.
IX
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AUTHORS, CONTRIBUTORS, AND REVIEWERS
Report Managers
Denice Shaw, Ph.D.1 (April 2009-November 2010)
Robert J. Frederick, Ph.D.1 (November 2010-present)
Authors (in alphabetical order)
Britta Bierwagen, Ph.D.1
Alice Chen, Ph.D.2
Christopher M. Clark, Ph.D.1
Rebecca S. Dodder, Ph.D.3
Robert J. Frederick, Ph.D.1
Anne Grambsch1
Timothy L. Johnson, Ph.D.3
Fran Kremer, Ph.D.4
Contributors (in alphabetical order)
Paul N. Argyropoulos7
Richard W. Baldauf, Ph.D.3
Andrea Barbery8
William K. Boyes, Ph.D.3
Randy Bruins, Ph.D.4
Ward Burns9
Philip J. Bushnell, Ph.D.3
Rebecca Edelstein, Ph.D.10
Julia Gamas11
Ian Gilmour, Ph.D.3
John Glaser, Ph.D.4
AlanD. Hecht, Ph.D.1
Karen Laughlin, Ph.D.7
Michael C. Madden, Ph.D.3
Maricruz MaGowan12
C. Andrew Miller, Ph.D.3
Stephen D. LeDuc, Ph.D.1
Brenda Lin, Ph.D.2
Adrea T. Mehl, Ph.D.5
Philip E. Morefield1
Donna Perla, MPH6
Caroline E. Ridley, Ph.D.1
Denice Shaw, Ph.D.1
Kenneth Moss10
Roberta Parry13
Mark C.Segal, Ph.D.10
Victor Serveiss
Karrie-Jo Shell1
Betsy Smith, Ph.D.3
Raymond Smith, Ph.D.4
Stephanie Syslo1
Patti Truant, MPH1
Barbara T. Walton, Ph.D.
LidiaS. Watrud,Ph.D.16
Jim Weaver, Ph.D.16
1 9
Gregory Wilson
John Wilson, Ph.D.17
Doug Young, Ph.D.4
14
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AUTHORS, CONTRIBUTORS, AND REVIEWERS (CONTINUED)
1 U.S. Environmental Protection Agency, Office of Research and Development,
Washington, D.C.
Former AAAS Fellow with U.S. Environmental Protection Agency, Office of Research
and Development, Washington, D.C.
3 U.S. Environmental Protection Agency, Office of Research and Development, Research
Triangle Park, North Carolina
4 U.S. Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio
5 AAAS Fellow, U.S. Environmental Protection Agency, Region 8, Denver, Colorado
6 U.S. Department of Agriculture, Office of the Chief Scientist, Washington, D.C.
7 U.S. Environmental Protection Agency, Office of Air and Radiation, Washington, D.C.
8 U.S. Environmental Protection Agency, Office of Underground Storage Tanks,
Washington, D.C.
9 U.S. Environmental Protection Agency, Region 7, Kansas City, Kansas
10 U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics,
Washington, D.C.
11 U.S. Environmental Protection Agency, Office of Air and Radiation, Research Triangle
Park, North Carolina
1 9
U.S. Environmental Protection Agency, Office of Solid Waste and Emergency
Response, Washington, D.C.
13 U.S. Environmental Protection Agency, Office of Water, Washington, D.C.
14 U.S. Environmental Protection Agency, Region 4, Atlanta, Georgia
15 Former U.S. Public Health Fellow, U.S. Environmental Protection Agency, Office of
Research and Development, Washington, D.C.
16 U.S. Environmental Protection Agency, Office of Research and Development,
17 U.S. Environmental Protection Agency, Office of Research and Development, Ada,
Corvallis, Oregon
J.S. Enviro:
Oklahoma
Support Contractors
ERG, Lexington, Massachusetts
ICF, Fairfax, Virginia
Versarlnc., Springfield, Virginia
XI
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AUTHORS, CONTRIBUTORS, AND REVIEWERS (CONTINUED)
External Peer Review Panel (in alphabetical order)
Rosa Dominguez-Faus, M.Sc.
Rice University, Houston, Texas
Rebecca A. Efroymson, Ph.D.
Independent Consultant, Asheville,
North Carolina
Jason M. Evans, Ph.D.
University of Georgia, Athens,
Georgia
Joseph E. Fargione, Ph.D.
The Nature Conservancy,
Minneapolis, Minnesota
Jeffrey S. Gaffney, Ph.D. (Chair)
University of Arkansas at Little
Rock, Little Rock, Arkansas
Jason D. Hill, Ph.D.
University of Minnesota, Saint Paul,
Minnesota
Catherine L. Kling, Ph.D.
Iowa State University, Ames, Iowa
Susan E. Powers, Ph.D., PE
Clarkson University, Potsdam, New
York
Phillip E. Savage, Ph.D.
University of Michigan, Ann Arbor,
Michigan
Jon Van Gerpen, Ph.D.
University of Idaho, Moscow, Idaho
May M. Wu, Ph.D.
Argonne National Laboratory,
Lemont, Illinois
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ACKNOWLEDGMENTS
Colleagues from the EPA Biofuels Steering Committee (chaired by Dr. Alan Hecht), the
U.S. Department of Agriculture, and the U.S. Department of Energy provided valuable
information in the conceptual phases of this report and reviewed versions as they were
developed. Many EPA reviewers from the Office of Air and Radiation, Office of Water, Office
of Solid Waste and Emergency Response, Office of Chemical Safety and Pollution Prevention,
and Regions 6 and 9 were very instrumental in determining the content and focus of the report.
Dr. Kate Schofield was consulted for the development of the conceptual models. Drs. Jeffrey
Frithsen and Michael Slimak provided management support throughout all stages of the report
development and review. We acknowledge the many reviewers who provided comment through
the public docket. Contract support was provided by ERG under contract GS-10F-0036K and
ICF under contract EP-C-09-009. Versar Inc. organized the independent external peer review of
the draft report under contract EP-C-07-025.
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Executive Summary
EXECUTIVE SUMMARY
This report is the first of the U.S. Environmental Protection Agency's (EPA's) triennial
reports to Congress required under the 2007 Energy Independence and Security Act (EISA).
EISA requires EPA to revise the Renewable Fuel Standard (RFS) program to increase the
volume of renewable fuel blended into transportation fuel from 9 billion gallons per year in 2008
to 36 billion gallons per year by 2022. The revised standards (RFS2), finalized in 2010, establish
new specific annual volume requirements for cellulosic biofuel, biomass-based diesel, advanced
biofuel, and total renewable fuel in transportation fuel. Increasing the amounts of domestically
produced renewable fuels addresses two goals of EISA: decreasing our dependence on foreign
sources of energy and decreasing greenhouse gas emissions.
EISA Section 204 calls for EPA to report to Congress on the environmental and resource
conservation impacts of the RFS program, including air and water quality, soil quality and
conservation, water availability, ecosystem health and biodiversity, invasive species, and
international impacts. EPA interpreted the requirements of Section 204 to be those
environmental impacts beyond the noteworthy reductions in greenhouse gas emissions associated
with the RFS program. For this report, EPA relies upon the existing peer-reviewed scientific
literature to review the impacts and mitigation opportunities across the entire biofuel supply
chain, including feedstock production and logistics and biofuel production, distribution, and use.
The information included here is considered foundational for future efforts to quantitatively
compare the environmental impacts of alternative scenarios for meeting the goals of the RFS2
program. Specifically, the report describes the current and potential future environmental
impacts from:
• Seven feedstocks—The report summarizes information for the two most
predominantly used, first-generation feedstocks (corn starch and soybeans) and
five other second-generation feedstocks (corn stover, perennial grasses, woody
biomass, algae, and waste), representing a range currently under development.
Because the RFS2 puts a limit of 15 billion gallons on the amount of corn starch-
derived biofuel that counts toward the volume requirement in 2022, an increased
reliance on other feedstocks is predicted.
• Two biofuels—The report summarizes information for ethanol (both
conventional and cellulosic) and biomass-based diesel, because they were the
most commercially viable in 2010 and/or projected to be the most commercially
available by 2022.
Overall Conclusions
Evidence to date from the scientific literature suggests that current environmental impacts
from increased biofuels production and use associated with EISA 2007 are negative but
limited in magnitude.
• Environmental impacts along the supply chain are greatest at the feedstock
production stage. Most activities, processes, and products, particularly those
occurring after feedstock production, are regulated and subject to limitations.
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Executive Summary
• Current environmental impacts are largely the result of corn production.
Corn starch-derived ethanol constituted 95 percent of the biofuel produced in
2009. In general, feedstock demand has been met by diverting existing corn
production or by replacing other row crops with corn, resulting in limited
additional environmental impacts.
Published scientific literature suggests a potential for both positive and negative
environmental effects in the future.
• Technological advances and market conditions will determine what
feedstocks are feasible, and where and how they will be cultivated.
• The magnitude of effects will be largely determined by the feedstock(s)
selected, land use changes, and cultivation practices.
• Overall impacts given most plausible land use changes and production
practices will likely be neutral or slightly negative. More adverse or beneficial
environmental outcomes are possible.
• Second-generation feedstocks have a greater potential for positive
environmental outcomes relative to first-generation feedstocks. However,
current production levels of second-generation biofuels are negligible and limited
by economic and technological barriers.
EISA goals can be achieved with minimal environmental impacts if existing conservation
and best management practices (BMPs) are widely employed, concurrent with advances in
technologies that facilitate the use of second-generation feedstocks.
• The feedstocks considered in this report all have the potential to support
sustainable domestic energy production. Realizing this potential will require
implementation and monitoring of conservation and BMPs, improvements in
production efficiency, and implementation of innovative technologies at the
commercial scale.
• International partnerships and federal coordination are needed to accelerate
progress toward sustainable and secure energy production.
Specific Environmental and Resource Conservation Conclusions
• Land use. Many potential impacts of biofuel production are the result of land use
conversion. An expansion of cropland in response to demand for biofuels is
projected, though not yet observed. Production of corn and soybean on land
currently enrolled in the Conservation Reserve Program (CRP) will result in the
most negative environmental impacts. In comparison, other land use conversions,
for example CRP to perennial grasses, would have more moderate environmental
impacts.
• Water quality. Impacts on water quality from biofuels in the United States are,
and likely will be, primarily driven by fertilizer and other chemical inputs at the
feedstock production stage. Impacts to date from EISA are considered moderately
negative, resulting primarily from an intensification of corn production
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Executive Summary
contributing to eutrophication, coastal hypoxia, and other areas of concern. In
comparison, second-generation feedstocks offer substantial opportunities for
improvement regarding water quality impacts.
Water quantity. Most current feedstock production does not require irrigation,
but water use will increase if future production expands into drier areas. Per unit
volume, water use for feedstock irrigation can be 100 to 1,000 times higher than
for feedstock-to-biofuel conversion processes. Adverse water availability impacts
will most likely arise in already stressed aquifers and surface watersheds.
Soil quality. Biofuel feedstock production can impact soil quality through
erosion, organic matter, and nutrient content. Perennial feedstocks are generally
better for soil quality than annual row crops; however, feedstock impacts will be
largely determined by which land use changes occur, if any. High corn stover
removal rates are of particular concern due to likely increases in soil erosion and
decreases in organic matter.
Air quality. While there are some localized impacts, the biofuel volumes required
by RFS2 have relatively little impact on national average ambient concentrations
of air toxics. Further increases in the use of biofuels will impact emissions and
ambient concentrations of "criteria" pollutants (pollutants for which EPA sets
ambient air quality standards) and a variety of air toxic compounds. Emissions
occur at all stages of the biofuel supply chain and effects will likely vary across
the country. Ozone concentrations are expected to rise in many areas, although a
few highly populated areas will experience reductions.
Ecosystem health. Feedstock cultivation can significantly affect biodiversity
through habitat conversion, especially on CRP lands, from exposure of flora and
fauna to pesticides; through sedimentation and eutrophi cation in water bodies
resulting from soil erosion and nutrient runoff, respectively; or from water
withdrawals resulting in decreased streamflows.
— Forests, grasslands, and wetlands. Shorter harvest intervals for short-
rotation woody crops; residue harvesting; and conversion of pasture, CRP
lands, or small, unregulated wetlands can decrease habitat availability and
biodiversity. Moderate thinning and best management or conservation
practices can increase some habitats, species diversity, and abundance.
— Invasive species. Weed risk assessments predict that switchgrass and
some woody crop species or varieties could become invasive in some
regions, but that corn, soybean and perennial grasses such as Giant
Miscanthus, pose little risk.
International. Increases in U.S. biofuel production and consumption volumes
may affect many different countries as trade patterns and prices adjust in response
to global supply and demand. This could result in land use change and affect air
quality, water quality, and biodiversity, but the location and magnitude of impacts
are uncertain.
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Executive Summary
This first report summarizes and synthesizes peer-reviewed literature through July 2010.
The report does not include, nor do its overall findings encompass, a life cycle analysis of
greenhouse gas emissions. Such an analysis was previously done for the Regulatory Impact
Analysis (RIA) of the RFS2. EPA's RFS2 RIA found that the EISA-mandated revisions to the
RFS2 program are expected to achieve an annual 138 million metric ton reduction in carbon
dioxide-equivalent emissions by 2022 compared to continued reliance on petroleum-based fuels.
This first report also does not present environmental impacts relative to petroleum-based
transportation fuels; such a comparison is recommended for the next report. Quantitative
assessments are presented where there is sufficient scientific literature to support such an
assessment; however, in most cases only qualitative assessments are feasible due to
methodological and informational limitations.
Recommendations
To promote sustainable approaches, EPA recommends:
• Incorporating the environmental impacts of biofuel production and use described
in this report into comprehensive life cycle assessments, including comparisons to
fossil fuels and other energy sources.
• Ensuring the success of current and future environmental biofuel research through
improved cooperation and sustained support.
• Improving the ability of federal agencies within their respective authorities to
develop, implement, and monitor best management and conservation practices
and policies that will avoid or mitigate negative environmental effects from
biofuel production and use. This will involve coordination among diverse
stakeholders, including state agencies, research scientists, and landowners.
• Engaging the international scientific community in cooperative efforts to identify
and implement sustainable biofuel and land use practices that minimize
environmental impact.
Because biofuel impacts cross many topics and Agency responsibilities, EPA will likely
address these recommendations through continued and strengthened cooperation with state and
federal agencies, including the U.S. Departments of Agriculture and Energy, and international
partners.
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Chapter 1: Introduction
1. INTRODUCTION
In December 2007, Congress enacted Public Law 110-140, the Energy Independence and
Security Act (EISA), to reduce U.S. energy consumption and dependence on foreign oil, and to
address climate change through research and implementation of strategies to reduce greenhouse
gases (GHGs). In accordance with these goals, EISA requires the U.S. Environmental Protection
Agency (EPA) to revise the Renewable Fuel Standard (RFS) program, created under the 2005
Energy Policy Act,1 to increase the volume of renewable fuel2 required to be blended into
transportation fuel from 9 billion gallons per year in 2008 to 36 billion gallons per year by 2022.
EPA finalized revisions to the RFS program in February 2010. The revised statutory
requirements (commonly known as the RFS2) establish new specific annual volume standards
for cellulosic biofuel, biomass-based diesel, advanced biofuel, and total renewable fuel that must
be used in transportation fuel (see Chapter 2). The purpose of this report is to examine the
environmental and resource conservation impacts of this change, as required under EISA Section
204.
EISA Section 204 calls for EPA to report to Congress every three years on the
environmental and resource conservation impacts of increased biofuel production and use as
follows:
In General. Not later than 3 years after the enactment of this section and every 3 years
thereafter, the Administrator of the Environmental Protection Agency, in consultation with the
Secretary of Agriculture and the Secretary of Energy, shall assess and report to Congress on the
impacts to date and likely future impacts of the requirements of Section 211(o) of the Clean Air
Act3 on the following:
1. Environmental issues, including air quality, effects on hypoxia, pesticides,4
sediment, nutrient and pathogen levels in waters, acreage and function of waters,
and soil environmental quality.
2. Resource conservation issues, including soil conservation, water availability, and
ecosystem health and biodiversity, including impacts on forests, grasslands, and
wetlands.
3. The growth and use of cultivated invasive or noxious plants and their impacts on
the environment and agriculture.
1 The 2005 Energy Policy Act amended the Clean Air Act and established the first national renewable fuel
standards. The statute specifies the total volume of renewable fuel that is to be used based on the volume of gasoline
sold in the U.S. each year, with the total volume of renewable fuel increasing over time to 7.5 billion gallons in
2012.
2 To be considered "renewable," fuels produced by biorefmeries constructed after EISA's enactment on December
19, 2007, must generally achieve at least a 20 percent reduction in life cycle greenhouse gas emissions compared to
petroleum fuels.
3 EISA 2007 amended Section 21 l(o) of the Clean Air Act to include the definitions and requirements of RFS2.
4 Pesticides include antimicrobials, fungicides, herbicides, insecticides, and rodenticides.
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Chapter 1: Introduction
4. The report shall include the annual volume of imported renewable fuels and
feedstocks for renewable fuels, and the environmental impacts outside the United
States of producing such fuels and feedstocks. The report required by this
subsection shall include recommendations for actions to address any adverse
impacts found.
A key feature of EISA is the establishment of mandatory life cycle GHG reduction
thresholds. EPA used state-of-the-art models, data, and other information to assess the GHG
impacts of biofuels, as described in the Final Regulatory Impact Analysis (RIA) (U.S. EPA,
2010a). To ensure that it used the best science available, EPA conducted a formal, independent
peer review of key components of the analysis. The modeling of GHG emissions in the RIA
(U.S. EPA, 2010a) provides a reasonable and scientifically sound basis for making threshold
determinations and estimating GHG impacts. Accordingly, this report does not attempt an
extensive evaluation of carbon dioxide or other GHGs, nor does it attempt to encompass GHG
impacts in its conclusions. Instead, it provides complementary information to the GHG impacts
described in the RIA (U.S. EPA, 2010a), which should be consulted for more information on this
topic.
This is the first of EPA's triennial reports on the current and potential future
environmental impacts associated with the requirements of Section 21 l(o) of the Clean Air Act.
This report reviews environmental and resource conservation impacts, as well as opportunities to
mitigate these impacts, at each stage of the biofuel supply chain: feedstock production, feedstock
logistics, biofuel production, biofuel distribution, and biofuel use. This foundation supports
efforts to quantitatively compare the environmental impacts of alternative scenarios for meeting
the goals of the RFS2 program.
This report emphasizes domestic impacts; however, the substantial market created for
biofuels by the United States, Brazil, and other countries has important global implications. For
example, countries that produce (or will produce) feedstocks that are converted to biofuels that
qualify for use in the United States will experience direct impacts; other countries (including the
United States) will have to adapt to changing agricultural commodity distributions that result
from diversion of food exports to biofuel production. As required under EISA Section 204, this
report describes the impacts of increased feedstock and biofuel production in other countries as a
result of U.S. policy.
This first triennial Report to Congress represents the best available information through
July 2010 and reflects the current understanding about biofuel production and use, including
input gained through consultation with the U.S. Departments of Agriculture and Energy.
Quantitative assessments are presented, where possible, using the most recently available data
through July 2010; however, in most cases only qualitative assessments were feasible due to
uncertainties and lack of data and analyses in the peer-reviewed literature. The information
included here is considered foundational for future efforts to quantitatively compare the
environmental impacts of alternative scenarios for meeting the goals of the RFS2 program. This
initial report serves as a starting point for future assessments and for taking action to achieve the
goals of EISA. Future reports will reflect the evolving understanding of biofuel impacts in light
of new research results and data as they become available.
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Chapter 1: Introduction
1.1. Organization of This Report
Chapter 2 provides background on EISA, including the volume, feedstocks, and GHG
thresholds required under the Act; it also describes the approach and coverage of this report.
Chapter 3 focuses on the first stage of the biofuel production process, feedstock production,
which includes cultivation and harvest. For each feedstock, this chapter assesses impacts on
water, air, soil, and ecosystems. A summary of impacts on specific habitats is also provided.
Chapter 4 covers the remaining stages of biofuel production: feedstock logistics and biofuel
production, distribution, and use. Environmental impacts are evaluated for two main biofuels:
ethanol and biodiesel. Chapter 5 discusses the potential impacts associated with imported
biofuels. Currently, imported ethanol and biodiesel supply a highly variable, but relatively small
percentage of U.S. biofuel consumption (U.S. EIA, 2009; U.S. ITC, 2010; ERS, 2010a). If this
percentage increases, expanded analysis of international impacts associated with imported
biofuels may be necessary in future versions of this report. Chapter 6 provides a synthesis and
conclusions based on an assessment of the literature. Since many feedstock technologies are in
the early stages of research and development, empirical and monitoring data relevant to
environmental impacts are limited, and projections of their potential future use are highly
speculative. Chapter 6 also describes recommendations for improving scientific understanding,
as well as practices for minimizing environmental impacts. This report is the first step toward the
capability to conduct a biofuels environmental life cycle assessment (LCA), which can provide
the basis for future reports to Congress. Chapter 7 describes a vision for those future reports.
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Chapter 2: Background and Approach
2. BACKGROUND AND APPROACH
2.1. EISA and RFS2 Requirements for Biofuel Production and Use
The Renewable Fuel Standard as amended by the Energy Independence and Security Act
(EISA) (RFS2) establishes new specific annual volume standards for four categories of
renewable fuels that must be used in transportation fuel:5 cellulosic biofuel, biomass-based
diesel, advanced biofuel, and total renewable fuel (see the glossary in Appendix A for fuel
definitions). Under RFS2, conventional biofuel (i.e., ethanol derived from corn starch) with a
maximum volume target and "additional renewable fuels"6 are included as eligible fuels to meet
the total renewable fuel standard. The revised statutory requirements also include new definitions
and criteria for both renewable fuels and the feedstocks used to produce them,7 including new
greenhouse gas emission (GHG) reduction thresholds as determined by the life cycle assessment
(LCA) that EPA conducted as part of its Regulatory Impact Analysis (RIA) during the final
RFS2 rulemaking (U.S. EPA, 2010a).
Table 2-1 shows the RFS2 annual renewable fuel standards through 2022. Total
renewable fuel under the standard will increase to 36 billion gallons per year (bgy) by 2022 (of
which corn starch ethanol is not to exceed 15 bgy).
While EISA establishes the renewable fuel volumes shown in Table 2-1, it also requires
the EPA Administrator to set the volume standards each November for the following year based
in part on information provided by the U.S. Energy Information Administration (U.S. EIA) and
other data indicating the commercial capacity for producing cellulosic biofuels. EISA therefore
requires the EPA Administrator to adjust the cellulosic standard, and potentially the total
advanced biofuel and total renewable fuel standards, each year based on this assessment. For
2010, the Administrator adjusted the cellulosic standard from 0.1 bgy (100 million gallons per
year) in RFS2 to 5.0 million gallons, but did not adjust the total advanced or total renewable fuel
standard.8 Therefore, the final 2010 standard for total renewable fuel is set at 12.95 bgy, with
specific targets for cellulosic biofuel (5.0 million gallons per year), biomass-based diesel (1.15
bgy, combining the 2009 and 2010 standards as proscribed in RFS2), and total advanced biofuel
(0.95 bgy).
5 Transportation fuel includes fuels used in motor vehicles, motor vehicle engines, non-road vehicles, or non-road
engines (except for ocean-going vessels).
6 EISA defines "additional renewable fuel" as "fuel produced from renewable biomass that is used to replace or
reduce fossil fuels used in heating oil or jet fuel." Though RFS2 does not specify a volume standard for this fuel
category, it does allow renewable fuel blended into heating oil or jet fuel to count toward achieving the standard for
total renewable fuel. More information about "additional renewable fuel" can be found in Section Il.b.e of the final
RFS2 rule, available at http://www.epa.gov/otaq/fuels/renewablefuels/regulations.htm.
7 EISA requires that all renewable fuel be made from feedstocks that meet the new definition of renewable biomass,
which includes certain land use restrictions. For full details, see Section 3.1.
8 Although EISA specified a 2010 cellulosic biofuel requirement of 100 million gallons/year, as shown in Table 2-1,
EPA determined that this level was not achievable for 2010. The U.S. EIA projected 5 million gallons/year of
cellulosic production for 2010 (6.5 million gallons ethanol equivalent), and EPA accepted this as the 2010 standard.
While this is lower than the level specified in EISA, no change to the advanced biofuel and total renewable fuel
standards was warranted due to the inclusion of an energy-based equivalence value for biodiesel and renewable
diesel.
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Chapter 2: Background and Approach
Table 2-1: RFS2 Renewable Fuel Requirements (Billion Gallons per Year)1
a,b
Year
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
Renewable Fuel
Conventional
Biofuel
9.0
10.5
12.0
12.6
13.2
13.8
14.4
15.0
15.0
15.0
15.0
15.0
15.0
15.0
15.0
Advanced Biofuel
Cellulosic Biofuel
n/a
n/a
O.ld
0.25
0.5
1.0
1.75
3.0
4.25
5.5
7.0
8.5
10.5
13.5
16.0
Biomass-Based
Diesel
n/a
0.5
0.65
0.80
1.0
TBDe
TBDe
TBDe
TBDe
TBDe
TBDe
TBDe
TBDe
TBDe
TBDe
Advanced Biofuel0
n/a
0.6
0.95
1.35
2.0
2.75
3.75
5.5
7.25
9.0
11.0
13.0
15.0
18.0
21.0
Total
Renewable
Fuel
9.0
11.1
12.95
13.95
15.2
16.55
18.15
20.5
22.25
24.0
26.0
28.0
30.0
33.0
36.0
a The requirements for cellulosic biofuel, biomass-based diesel, advanced biofuel, and total renewable fuel are
minimum required volumes that must be achieved and may be exceeded. The conventional biofuel requirement is
a cap that cannot be exceeded.
b Note that the RFS2 volume requirements are nested: cellulosic biofuel and biomass-based diesel are forms of
advanced biofuel; and advanced biofuel and conventional biofuel are forms of total renewable fuel.
0 Note that the sum of the required amounts of cellulosic biofuel and biomass-based diesel is less than the required
volume of advanced biofuel. The additional volume to meet the advanced fuel requirement may be achieved by
the additional cellulosic biofuel and biomass-based diesel (i.e., beyond the required minimum) and/or by other
fuels that meet the definition of advanced biofuel (e.g., sugarcane ethanol).
d As described above, and as allowed under EISA, the EPA Administrator determined that the original RFS2
standard of 0.1 bgy for cellulosic biofuel was not achievable for 2010 and therefore decreased this standard to 5
million gallons for 2010.
e To be determined by EPA through a future rulemaking, but no less than 1.0 billion gallons. This requirement was
designated under EISA as "to be determined" with a minimum requirement because of the uncertainty about
future capacity to produce fuel that meets the biomass-based diesel definition.
Source: U.S. EPA, 2010a.
2.1.1. Life Cycle Greenhouse Gas Thresholds
The Act established specific life cycle GHG emission thresholds for each of four types of
renewable fuels, requiring a percentage improvement compared to life cycle GHG emissions for
gasoline or diesel (whichever is being replaced by the renewable fuel) sold or distributed as
transportation fuel in 2005. GHG LCA evaluates emissions resulting from all stages of a
product's development—from growth of a feedstock to end use. These life cycle performance
improvement thresholds are listed in Table 2-2.
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Chapter 2: Background and Approach
Table 2-2: Life Cycle GHG Thresholds Specified in EISA
(Percent Reduction from 2005 Baseline)
Renewable fuel3
Advanced biofuel
Biomass-based diesel
Cellulosic biofuel
20%
50%
50%
60%
a The 20 percent criterion generally applies to renewable fuel from new
facilities that commenced construction after December 19, 2007.
EPA's methodology for conducting the GHG LCA included use of agriculture sector
economic models to determine domestic agriculture-sector-wide impacts and international
changes in crop production and total crop. Based on these modeling results, EPA estimated GHG
emissions using the U.S. Department of Energy's Greenhouse Gases, Regulated Emissions, and
Energy Use in Transportation (GREET) model defaults and Intergovernmental Panel on Climate
Change (IPCC) emission factors. The GHGs considered in the analysis were carbon dioxide
(CC>2), methane (CH/i), and nitrous oxide (N2O). Biofuel process energy use and associated GHG
emissions were based on process models for the different pathways considered. For ethanol and
biodiesel, EPA's RFS2 RIA (U.S. EPA, 2010a) projected that:
• Ethanol produced from corn starch at a new, natural-gas-fired facility (or
expanded capacity from an existing facility) using advanced efficient technologies
will comply with the 20 percent GHG emission reduction threshold.
• Ethanol produced from sugarcane will comply with the 50 percent GHG reduction
threshold for the advanced fuel category.
• Biodiesel from soybean oil and renewable diesel from waste oils, fats, and greases
will comply with the 50 percent GHG threshold for the biomass-based diesel
category.
• Diesel produced from algal oils will comply with the 50 percent GHG threshold
for the biomass-based diesel category.
• Cellulosic ethanol and cellulosic diesel (based on the modeled pathways) will
comply with the 60 percent GHG reduction threshold applicable to cellulosic
biofuels.
Based on the assessment described above, EPA projected a reduction of 138 million
metric tons of C(^-equivalent emissions annually by 2022 compared to projected 2022
emissions without the EISA-mandated changes (see the RFS2 RIA [U.S. EPA, 2010a] for
details).
2.1.2. Life Cycle Assessment and Environmental Impacts
LCAs evaluate environmental impacts resulting from all stages of a product's
development—from feedstock production through biofuel use and disposal (see the box on the
next page). As described above, EPA previously evaluated the aggregate quantity of GHG
(including direct emissions and significant indirect emissions such as significant emissions from
land use changes) related to the full life cycle, including all stages of fuel and feedstock
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Chapter 2: Background and Approach
production, distribution, and use by the ultimate consumer (U.S. EPA, 2010a). Currently, LCA
does not include all of the environmental and resource conservation impacts required by Section
204. Extending this methodology to include these effects poses significant challenges, and could
not be done for this report. However, it may be possible to draw from the considerable work that
has already been done to develop LCA and other methodologies, including ecological and human
health risk assessment, to assess impacts of specific biofuel products and processes for future
reports.
LCA and Net Energy Balance
There has been considerable work to develop LCA frameworks and apply them to specific products
or processes, including efforts to standardize the approaches and scope of an LCA to enable comparison
across similar products (ISO, 2006). Recent reviews have examined the limitations and biases that have
framed a variety of LCA reports onbiofuels (Von Blottnitz and Curran, 2007; Gnansounou et al., 2009;
Davis et al., 2009). These highlight the importance of understanding that the results of any LCA will depend
on how the boundaries for a particular analysis are set. Given the highly interconnected economic, energy,
and agricultural systems involved in the production and use of biofuels, it is important to recognize that
biofuel production and use will have impacts well beyond the farm-to-vehicle supply chain. Although the
impacts will become incrementally smaller as distance from that specific supply chain increases (e.g., the
change in steel production to meet demand for construction of biofuel conversion processes), choosing finite
boundaries will necessarily exclude some impacts. The National Research Council (NRC, 2010b) used an
LCA framework to do a partial analysis intended to provide detailed quantitative assessments of the
comparative health and environmental benefits, risks, and cost of existing fossil fuels as well as future mixes
of transportation technologies and fuels. While the analysis provided comparative bottom lines for a variety
of transportation fuel production processes and uses, the authors acknowledged that they were
"constrained—by the limitations of the GREET model and the scarcity of available national databases on
many ecosystem impacts and other impacts—to quantify only those impacts from energy use and the air
quality emissions produced during these operations." They also limited their assumptions to "reasonable
speculations" and selected to report only on direct land use effects.
Net Energy Balances (NEBs) can be used to compare the energy gain or loss associated with
different biofuel feedstocks or to compare biofuels and fossil fuels. Analysis of NEB does not directly
address environmental impacts, but it is a relevant metric in a full evaluation of biofuels. Putting NEB in the
context of other environmental impacts (e.g., environmental impacts per net energy gain/loss) can provide a
metric upon which environmental impact comparisons can be made. Hill et al. (2006) estimated an NEB of
1.25 for corn ethanol, only slightly below the lowest energy gain (1.29) estimated by Hammerschlag et al.
(2006). On the other hand, two studies reviewed by Farrell et al. (2006) showed a net energy loss when they
included the energy associated with manufacturing of farm machinery needed for biofuel feedstock
production and the construction of biofuel conversion facilities. Additional studies from U.S. Department of
Agriculture (USDA) (Shapouri et al., 2002, 2010) show a continuing improvement in the NEB for corn
ethanol production. The picture also improves when the energy embedded in co-products of the fuel
conversion process are taken into consideration (Shapouri et al., 2010).
Despite the limitations of LCA and NEB for evaluating many of the environmental impacts
specified by Section 204 of EISA 2007, they show great promise. With further development, they can
become the basis for estimating and comparing the potential natural resource and environmental impacts of
biofuel production and use under a range of scenarios.
2.1.3. Projected Fuel and Feedstock Use to Meet Required RFS2 Targets through 2022
Figure 2-1 summarizes the fuel types and volumes required to meet the targets through
2022, described in the RFS2 (see Table 2-1).
2-4
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Chapter 2: Background and Approach
40
35
30
01
*u
EUi
01
= x 25
Total
Renewable Fuel
o a.
§ c
5 o
o =
§>
re c
3 o
20
re e 15
10
Biomass Based Diesel
and Other Advanced Biofuel
2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Source: U.S. EPA, 2010a.
Figure 2-1: Renewable Fuel Volumes to Meet RFS2 Targets
In 2009, corn ethanol constituted 95 percent of total U.S.-produced renewable fuel, with
biodiesel made from soybean oil, other virgin vegetable oils, rendered fats, greases, and corn oil
from ethanol production accounting for almost all the remaining biofuel consumed (FAPRI,
2010a; U.S. EIA, 2010). However, as technologies improve, EPA expects more advanced
cellulosic feedstocks, such as agricultural residues (e.g., corn stover, sugarcane bagasse, wheat
residue, sweet sorghum pulp), forestry biomass, urban biomass waste, and dedicated energy
crops (e.g., switchgrass) to produce biofuels (U.S. EPA, 2010a). Present research is focused on
improving technologies to convert different feedstocks to biofuels in an economically viable
manner, and on determining sustainable biofuel production methods.
With respect to biodiesel, EPA expects continued use of soybean oil, which made up 54
percent of feedstock used for biodiesel in 2009 (U.S. EIA, 2010), as well as a varying percentage
of other vegetable oils, rendered fats, greases, and corn oil from ethanol production through 2022
(see Table 3-2 for a more detailed breakdown) (U.S. EPA, 2010a). Algae could provide large
volumes of oil for the production of biomass-based diesel. However, several hurdles, including
technical issues, will likely limit production volumes between now and 2022 (U.S. EPA, 2010a).
Imported sugarcane ethanol, also represents a significant potential supply of biofuel by
2022 (U.S. EPA, 2010a). In 2009, the United States imported 198 million gallons of ethanol
(U.S. EIA, n.d.[c]). Import volumes are expected to grow as U.S. demand increases to meet the
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Chapter 2: Background and Approach
biofuel targets, although this will depend on the relative costs of U.S. biofuel production and
imported ethanol.
2.2. Regulatory Authority Relevant to Biofuel Environmental Impacts
The EPA, in conjunction with states, tribes, and local environmental agencies, has
statutory responsibility to regulate air emissions, water discharges, use of toxic substances,
microbial and pesticide use, and waste disposal. Many existing environmental regulations and
programs are applicable to the biofuel supply chain, including feedstock production and logistics,
biofuel production and distribution, and biofuel use. Thus, the direct point source discharges and
emissions associated with the biofuel supply chain are expected to be effectively controlled by
existing environmental statutes. It is the impacts associated with non-point pollution and shifts in
land-use patterns, however, that pose the greatest concern from an environmental perspective.
EPA's primary federal regulatory authority is derived from the Clean Air Act (CAA), the
Clean Water Act (CWA), the Federal Insecticide Fungicide and Rodenticide Act (FIFRA), the
Resource Conservation and Recovery Act (RCRA), and the Toxic Substances Control Act
(TSCA). Under the CAA, EPA has broad direct statutory authority to regulate fuel quality and
emissions from refining and production facilities for all fuels, including biofuels. The CAA also
establishes limits for mobile source (vehicular) emissions. The CWA requires permits for point
source discharges to waters of the United States, development of water quality standards for
receiving waters, and Total Maximum Daily Loads (TMDLs) for water bodies where water
quality standards have not been met. FIFRA establishes standards for storage and use of
pesticides in a manner that does not harm human health or the environment. RCRA governs the
generation, storage, treatment, transport, and disposal of hazardous waste. TSCA requires
manufacturers and importers of new chemicals to submit "pre-manufacture" notices for EPA
review prior to manufacture and commercial use of new chemicals, including new fuels, new
biological materials, and new genetically engineered microorganisms used to produce biofuels or
co-products. Through the CWA's Spill Prevention, Control and Countermeasure rule, EPA has
enforceable regulations to control water quality impacts from spills or leaks of biofuel products
and byproducts. In addition, the Safe Drinking Water Act establishes maximum contaminant
levels (MCLs) for more than 90 drinking water contaminants to ensure public health. These
statutes provide opportunities within the existing regulatory framework to regulate and mitigate
some of the potential adverse health and environmental effects of biofuels. Selected
environmental laws relevant to the production and use of biofuels are summarized in Appendix
B. A detailed analysis of how each environmental statute might mitigate the direct impacts of
biofuels was outside of the scope of this first report.
Generally, EPA program offices develop policies and regulations for these federal
statutes, while regional EPA offices, in partnership with the states and tribes, implement these
programs, ensure compliance, and enforce regulations. EPA and its regional offices work closely
with states and tribes to review permit applications for new facilities and to monitor
environmental impacts to ensure compliance with all permit conditions. EPA's Regional Office
in Kansas City, representing the major corn-growing states, has prepared two documents to help
biofuel facilities understand the full range of regulatory requirements (U.S. EPA 2007, 2008a)
that can mitigate a range of direct environmental impacts when appropriately implemented.
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Chapter 2: Background and Approach
2.3. Approach to the Section 204 Report
This report reviews the environmental implications of current and future biofuel
production and use, as discussed in the published peer-reviewed literature. An extensive review
was conducted on scientific literature published through July 2010, to identify impacts across the
biofuel supply chain, including current and anticipated future impacts from feedstock production,
feedstock logistics, and biofuel production, distribution, and use. This report summarizes much
of the available information and identifies research needed to evaluate potential environmental
impacts from a life cycle perspective and quantify them using more substantive and systematic
assessment tools.
Any discussion of the environmental impacts of an energy source begs the question,
"compared to what?" In the case of biofuels, some studies have provided comparisons to fossil
fuels as a reference point for focusing on particular outputs such as GHG emissions or paniculate
matter emissions. In the case of other environmental impacts (e.g., water quality), most
comparisons are between different biomass feedstocks (e.g., corn versus perennial grasses),
rather than biomass feedstocks in aggregate compared to fossil fuels. While references to such
analyses are made throughout the report, EPA decided a comprehensive, quantitative
comparative analysis was beyond the scope of the current effort. Instead, EPA explored the
information that will be needed to prepare for such an analysis, and allow for the successful use
of methods such as LC A for evaluating and comparing full environmental impacts in future
reports.
EISA 2007 mandates the use of increasing volumes of renewable fuel. Ideally, the
Section 204 assessment would be based on a comparison between two projections: a baseline (or
reference scenario) and an EISA 2007 scenario. There are a number of candidates for the
baseline scenario. For example, the RIA (U.S. EPA, 2010a) for the RFS2 included (1) a
projection of renewable fuel volumes without the enactment of EISA (e.g., the U.S. EIA's
Annual Energy Outlook 2007 reference case), (2) a projection assuming the mandated renewable
fuel volumes under the RFS Program from legislation preceding EISA 2007, the Energy
Protection Act of 2005, and (3) a specific year that represents conditions prior to the rapid
increase in corn acres planted after 2007. Each of these scenarios has important insights to
contribute, as each answers slightly different questions. Many other studies assume different
reference conditions, baselines, and scenarios, all of which provide useful information on
potential environmental impacts. In order to incorporate these insights and information, this
report does not restrict analysis to a specific, quantitative baseline against which environmental
impacts can be measured. Instead, it uses a broad, qualitative assessment based on the peer-
reviewed literature, which provides a variety of baselines.
2.3.1. Qualitative Synthesis of the Literature Reviewed for This Report
Chapter 6 presents a qualitative synthesis and the underlying assumptions to estimate the
range and magnitude of the environmental impacts of producing corn, soybeans, corn stover,
perennial grasses, woody biomass, and algae; and corn ethanol, soybean biodiesel, and cellulosic
ethanol for transportation biofuel (Tables 6-1 and 6-2, Figure 6-1). This synthesis is based on the
information reviewed in preceding chapters of this report, and covers environmental impacts
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Chapter 2: Background and Approach
attributable to activities across the entire biofuels supply chain, from cultivation of feedstocks
through the use of fuel.
Tables 6-1 and 6-2 present assumptions underlying the maximum potential range of
domestic environmental impacts associated with the production of biofuels under RFS2, as well
as conditions for negligible and the most plausible impacts within that maximum potential range.
The relative, qualitative values across feedstocks and impact categories presented in these figures
are based on the consensus of the authors. Full details of the analysis, including the methodology
and conventions used to develop and present the information are described in Sections 6.2 and
6.3.
This synthesis addresses many complexities covered in this report, including the
dependence of impacts on the type of feedstock or fuel used, and on management practices, land
use change, and conversion technologies, but does not incorporate other environmental (e.g.,
GHG emission reductions), economic, and social issues relevant to decision making. Further
complexities will be explored in subsequent reports.
Although EPA recognizes the limitations of a qualitative literature review (e.g.,
inconsistent baselines, assumptions, and endpoints across studies), modeling efforts are not
sufficiently developed to allow comprehensive quantitative analysis of all environmental impacts
required of Section 204 of EISA 2007. Quantitative analyses on subsets of topics addressed in
this report have been summarized (e.g., Malcolm et al., 2009), and progress on quantitative and
integrated assessments is an important goal for future reports.
2.3.2. Biofuel Production Stages Discussed in This Report
There are five main stages in the biofuel supply chain: feedstock production, feedstock
logistics (transport, storage, and distribution), fuel production, fuel distribution, and fuel use
(Figure 2-2). Environmental impacts can be generated at all stages of biofuel feedstock
production and processing. The specific impacts associated with a particular feedstock or biofuel
will vary depending on many factors, including the type, source, and method of feedstock
production; the technology used to convert the feedstock to fuel; methods used and distances
traveled to transport biofuels; the types and quantities of biofuels used; and controls in place to
avoid or mitigate any impacts. This report covers all five of the production stages.
Feedstock
Production
Land Use/
Conversion
Feedstock
Cultivation &
Harvest
Feedstock
Logistics
Transport, Storage&
Distribution
Biofuel
Production
Biofuel
Distribution
Conversion of Handling, Blending,
Feedstock to Transport & Storage
Biofuel
Vehicle Fueling &
Operation
Figure 2-2: Five Stages of the Biofuel Supply Chain
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Chapter 2: Background and Approach
2.3.3. Feedstocks and Fuels Discussed in This Report
There is uncertainty regarding which feedstocks will be used to meet the RFS2 targets in
the mid- to long term. A few feedstocks are already in use: corn, soybean, and others in smaller
quantities. Other feedstocks are in the early stages of research and development or their potential
future commercial viability is still unknown. This report focuses on seven feedstocks: the most
predominantly used (corn and soybeans) and five others (corn stover, perennial grasses, woody
biomass, algae, and waste materials) that represent a range of feedstocks currently under
development. The biofuels highlighted in this report are ethanol (both conventional and
cellulosic) and biomass-based diesel. Ethanol and biomass-based diesel are the focus because
they are currently the most commercially viable and/or are projected to be the most
commercially available by 2022, and they are the primary fuels currently projected to meet
RFS2. Future reports will analyze other feedstocks and fuels as technologies and commercial
viability change.
2.3.4. Impacts Discussed in This Report
This report focuses on environmental and resource conservation impacts specified in
EISA Section 204, as shown in Figure 2-3. It does not extensively discuss CC>2 or other GHGs,
nor do its findings encompass environmental benefits gained by GHG emissions reductions
established by the RFS2; interested readers are referred to the EPA's RFS2 RIA (U.S. EPA,
2010a). This report is complementary to the RIA.
The environmental and resource conservation impacts discussed in this report reflect a
complex set of interactions and feedbacks between land, soil, air, and water; future versions of
this report will explore these important complexities as enhanced data and analysis tools become
available. The state of knowledge does not permit a fully quantitative analysis of the impacts
associated with increased production of biofuels, especially those that are not currently deployed
at commercial scales (e.g., cellulosic, algae). Instead, this report compiles available information
and analyses on the nature and extent of impacts that might be expected to occur. Thus, it does
not use the EISA baselines and volumes, per se, against which impacts can be measured. A
number of important findings on the potential impacts of increased biofuel production and use
were found in the literature. These findings are based on different baselines and volumes from
the RFS2 RIA, but are important in ascertaining the nature and extent of potential impacts.
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Chapter 2: Background and Approach
RFS2-MandatedUseof
Biofuels
Environmental Issues
Resource Conservation
Issues
Air Quality
Water Quality *
Soil Quality
Soil Conservation
Water Availability
Ecosystem Health
and Biodiversity **
* Includes pesticides, sediments, nutrients, pathogens, and acreage/function of wetlands
** Includes invasive/noxious plants, forests, grasslands, wetlands, and other aquatic ecosystems
Figure 2-3: Environmental and Resource Conservation Issues Addressed in This Report
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.
ENVIRONMENTAL IMPACTS OF SPECIFIC FEEDSTOCKS
3.1. Introduction
The Energy Independence and Security
Act (EISA) requires that all renewable fuel be
made from feedstocks that meet the definition
of renewable biomass (see text box). Many
different feedstocks meet these requirements
and can be used to produce ethanol, other
biofuels, or biofuel components.
In 2009, 95 percent—or 10.9 billion
gallons—of total renewable fuel produced in
the United States was produced from corn and
refined almost entirely in the form of
conventional corn starch ethanol (FAPRI,
2010a; U.S. EIA, 2010). Soybean oil-based
biodiesel accounted for most of the
remainder—505 million gallons. EPA expects
that corn and soybean feedstocks will continue
to account for a large share of U.S. biofuel
production in the near future (U.S. EPA,
2010a). As of July 2010, there was neither
significant commercial-scale production of ethanol from cellulosic feedstocks, nor significant
biodiesel production from oil seed feedstocks other than soybean in the United States.
As the science and technology of cellulosic biofuel production improve, EPA expects an
increase in the use of cellulosic feedstocks to produce advanced biofuel. Such feedstocks include
agricultural residues (e.g., corn stover, sugarcane bagasse, and sweet sorghum pulp), forestry
biomass, urban waste, and dedicated energy crops (e.g., switchgrass) (U.S. EPA, 2010a).
Technologies for producing biodiesel from vegetable oils, recycled oils, rendered fats, greases,
and algal oils have been developed and tested at various scales from the laboratory to
demonstration plants to commercial facilities. EPA expects biodiesel from these feedstocks to
increase its market share as their production becomes more economically and technologically
feasible (U.S. EPA, 2010a).
The feedstocks discussed in this chapter include corn and soybeans, as well as four others
currently under development: corn stover, perennial grasses, woody biomass, and algae (see
Table 3-1). These feedstocks represent different cultivation and production practices. A brief
discussion of waste materials as a feedstock is also included.
Requirements for Renewable Fuels
Under EISA, all renewable fuel must be made from
feedstocks that meet the Act's definition of
renewable biomass:
• Planted crops and crop residue from agricultural
lands that were cleared prior to December 19,
2007, and were actively managed or fallow on
that date.
• Planted trees and tree residue from tree
plantations that were cleared prior to December
19, 2007, and were actively managed on that
date.
• Animal waste material and byproducts.
• Slash and pre-commercial thinnings from non-
federal forestlands that are neither old-growth
nor listed as critically imperiled or rare by a State
Natural Heritage program.
• Biomass cleared from the vicinity of buildings
and other areas at risk of wildfire.
• Algae.
• Separated yard waste and food waste.
As well, these feedstocks must meet life cycle
GHG thresholds (Table 2-2).
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Chapter 3: Environmental Impacts of Specific Feedstocks
Table 3-1: Primary Fuels and Feedstocks Discussed in This Report
EISA Biofuel Type
Conventional biofuel
Cellulosic biofuel
Biomass-based diesel
Biofuel
Ethanol
Ethanol
Biomass-based
diesel
Feedstock
Corn starch
Corn stover
Perennial grasses
Woody biomass
Soybeans
Algae
The Renewable Fuel Standard as amended by the EISA (RFS2) prescribes allowable
conversions of land uses to specific renewable fuel feedstocks. Corn, corn stover, soybeans, and
perennial grasses may only be grown on lands that were in agricultural production prior to
December 19, 2007 (U.S. EPA, 2010a). These lands comprise cropland, pasture, and currently
fallow lands, including land enrolled in the Conservation Reserve Program (CRP). Woody
biomass can only be grown on lands that were active forest plantations prior to December 19,
2007, while residue harvesting and thinning can occur on non-federal forestlands (U.S. EPA,
2010a). The scientific literature that precedes fmalization of the RFS2 generally uses different
assumptions about land use conversions and subsequent environmental effects (e.g., Walsh et al.,
2003; Volk et al., 2006). For consistency across feedstocks, impacts are frequently compared
with those of row crops, even when such conversions are either not currently economically likely
(e.g., conversion of row crops to grasses) or not allowed under the RFS2 (e.g., conversion of
forests to row crops). The literature to date repeatedly compares environmental impacts between
feedstock types, however, and this report accordingly includes such information.
This chapter reviews the actual (where known) and potential environmental impacts of
producing these feedstocks. Actual environmental impacts will vary, depending on the number of
acres in production, cropping techniques, implementation of conservation and best management
practices (BMPs), location of the crop acreage, hydrology, soils, species composition, and other
geographic factors. Feedstock production impacts are considered during the cultivation and
harvest processes (see Figure 2-2). Potential impacts associated with the subsequent four stages
of the biofuel supply chain are presented in Chapter 4. Row crop feedstocks (corn, corn stover,
and soybean), which share many common traits, are discussed in Section 3.2. Sections 3.3 to 3.6
present potential effects associated with switchgrass, woody biomass, algae, and waste,
respectively. In addition to general ecosystem impacts, Section 3.7 reviews impacts on specific
ecosystems (forests, grasslands, and wetlands) as required under EISA Section 204. Section 3.8
reviews environmental concerns associated with genetic engineering of feedstocks.
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.2. Row Crops (Corn, Corn Stover, Soybeans)
3.2.1. Introduction
Overall, U.S. corn and soybean production has increased over the past decade. Increased
demand for biofuel provides additional incentive to continue research and development for
increasing crop production and yields. As shown in Figure 3-1, plantings of corn in the United
States have increased by almost 10 million acres since 2006, an increase of nearly 13 percent.
Soybean acres have increased by a more modest 1.9 million acres, or about 2.5 percent, since the
previous high in 2006. Yields for both corn and soybean have improved during the past two
decades (see Figure 3-2) (NASS, 2010a), moderating the need for increases in acreage.
180
170
160
150
S 90
g 80
1 70
60
50
40
30
All other principal crops
Soybean
CRP
2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Data source: NASS, 2010a.
Figure 3-1: U.S. Acres of Crops Planted and U.S. Acres Enrolled in the CRP
3.2.2. Overview of Environmental Impacts
Corn and soybean production entails the use of pesticides, fertilizer, water, and
fuel/energy, in addition to drainage systems in some areas. Each of these can affect the
environment. Changes in land cover, vegetation, and habitat have additional impacts on the
environment. Because corn stover is a byproduct of corn production, this report considers the
incremental environmental impacts from corn stover separately from those of grain-only
harvesting.
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Chapter 3: Environmental Impacts of Specific Feedstocks
180
2010
Data source: NASS, 2010a.
Figure 3-2: U.S. Corn and Soybean Yield
Cultivation of row crops such as corn and soybeans may lead to high levels of soil
erosion, nutrient loss, and pesticide and water use if not managed adequately (Groom et al.,
2008, Table 1). Agricultural conservation practices may be used to reduce or minimize the
impact of row crop agriculture on the environment. These practices include: (1) controlled
application of nutrients and pesticides through proper rate, timing, and method of application; (2)
controlling erosion in the field (e.g., reduced tillage, terraces, grassed waterways); and (3)
trapping losses of soil at the edge of fields or in fields through practices such as cover crops,
grassland and riparian buffers, controlled drainage for tile drains, and constructed/restored
wetlands (Dinnes et al., 2002; Blanco-Canqui et al., 2004; Blann et al., 2009; NRCS, 2010a).
The effectiveness of conservation practices, however, depends upon their adoption. The
U.S. Department of Agriculture (USD A) Conservation Effects Assessment Project (CEAP)
recently released a major study quantifying the effects of conservation practices commonly used
on cultivated cropland in the upper Mississippi River basin. It found that, while erosion control
practices are commonly used, there is considerably less adoption of proper nutrient management
techniques to mitigate nitrogen loss to water bodies (NRCS, 2010a).
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Chapter 3: Environmental Impacts of Specific Feedstocks
Even if conservation and BMPs are reliably implemented, they cannot be expected to
always lead to rapid improvements in environmental quality. A case study in the Chesapeake
Bay (CENR, 2010) found that the implementation of BMPs since 2000 has significantly lowered
loadings of nitrogen (72 percent of sites showed downward trends), total phosphorus (81 percent
of sites), and sediment (43 percent of sites). However, lower nutrient input has not yet improved
dissolved oxygen levels overall in the Chesapeake Bay, with the exception of small-scale
reductions in hypoxic zones.
3.2.3. Current and Projected Cultivation
In 2009, U.S. farmers planted 86 million acres of corn, harvesting 13.1 billion bushels
(NASS, 2010a). Approximately 4.5 billion bushels (or 34.9 percent of corn grain consumed
annually) were used for corn starch ethanol between September 2009 and August 2010 (ERS,
2010c, 2010d), up from 12.4 percent in 2004-2005 (see Figure 3-3; ERS, 2010b, 2010c).9 Corn
is grown throughout the United States, but the vast majority of the crop is grown in 11 states:
Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Nebraska, Ohio, South Dakota,
and Wisconsin. Figure 3-4 shows a map of planted acres by county in 2010.
40
35
30
25
20
15
10
5
o
JOWH'2001 2fl01,'20Q2 20
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Chapter 3: Environmental Impacts of Specific Feedstocks
Corn for All Purposes 2010
Planted Acres by County
for Selected States
Acres
Not Estimated
< 10,000
10,000- 24,999
25,000- 49,999
50,000- 99,999
100,000- 149,999
150,000 +
U.S. Department Agriculture. National Agricultural Statistics Service
Source: NASS, 2010b.
Figure 3-4: Planted Corn Acres by County
EISA establishes 15 billion gallons as the maximum amount of corn starch ethanol that
can contribute to meeting the 36 billion gallon per year renewable fuel target in 2022. Domestic
production, which totaled 10.9 billion gallons in 2009 (U.S. EIA, n.d.[b]), is expected to meet
this target in 2015 through a combination of increased corn yield, increased acreage dedicated to
ethanol production, including more continuous corn, and, potentially, improved efficiency in
converting corn starch to ethanol (Malcolm et al., 2009). Imported production totaled
approximately 200 million gallons in 2009. The USDA estimates that planted corn acreage will
remain at 89 to 90 million acres through 2019, despite increasing demand for biofuel in the
United States (USDA, 2010a). In the RFS2 analysis, EPA estimates that in order to produce 15
billion gallons of corn starch ethanol per year by 2022, the percentage of corn bushels dedicated
to ethanol could rise from the current 35 percent to 41 percent in 2022 (U.S. EPA, 2010a).
Corn stover—the stalks, leaves, husks, and cobs that are not removed from the fields
when the corn grain is harvested—provides another potential feedstock for meeting EISA
requirements. In the RFS2 Regulatory Impact Analysis (RIA), U.S. EPA (2010a) estimated that
7.8 billion gallons of ethanol could be produced from corn stover by 2022. Most corn stover
harvesting for biofuel is expected to be from the major corn-producing states. As of July 2010,
there was no commercial production of cellulosic ethanol from corn stover.
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Chapter 3: Environmental Impacts of Specific Feedstocks
After corn, soybean is the second largest agricultural crop (in terms of acreage) in the
United States. In 2010, American farmers planted 77.7 million acres of soybeans and harvested
3.4 billion bushels (NASS, 2010a). Soybean oil is the principal oil used for commercial
production of biodiesel in the United States, responsible for about half of total biodiesel
production. The rest comes from various other vegetable oils such as canola oil as well as waste
fats, tallow, and greases (see Table 3-2 for a more detailed breakdown) (U.S. EIA, 2010). In
harvest year 2008/2009, biodiesel accounted for approximately 5.5 percent of U.S. soybean
consumption.10 Almost 2 billion pounds of soybean oil (USD A, 2010b) yielded about half of the
505 million gallons of biodiesel produced in calendar year 2009 (U.S. EIA, n.d.[c]). This was a
significant decline from the production total in 2008 of 683 million gallons from soybeans (U.S.
EIA, n.d.[a]). Nonetheless, USDA expects biodiesel to account for approximately 7.7 percent of
soybean consumption in 2012/2013 and hold relatively steady through 2019. USDA estimates
that soybean acreage will level off at approximately 76 million acres through 2019 (USDA,
201 Ob).
Table 3-2: 2009 Summary of Inputs to U.S. Biodiesel Production"
Input
Feedstock inputs
Other inputs
Vegetable oils (canola, corn,
cottonseed, palm, soybean, and
other vegetable oils)
Animal fats (poultry fat, tallow,
white grease, and other animal
fats)
Recycled feedstock (yellow
grease and other recycled
feedstock)
Alcohol
Catalysts
2009 Total
(Million Pounds)
2,385
1,040
169
328
56
Percentage of Total
60.0%
26.1%
4.2%
8.2%
1.4%
a This table's contents must be considered as estimates due to withholding of confidential business information for
some of the input categories.
Source: U.S. EIA, 2010.
In terms of cultivation, soybeans are typically grown in rotation with corn, in the same
locations. Figure 3-5 shows that soybean production is centered in the upper Midwest and along
the Mississippi River Valley, with Iowa, Illinois, Indiana, Minnesota, and Nebraska representing
the top soybean-producing states.
Percentage of soybeans allocated to biodiesel calculated by dividing soybean oil allocated to production of
biodiesel by annual crushing yields and expressed as a function of total disposition.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Soybeans 2010
Planted Acres by County
for Selected States
Acres
Not Estimated
< 10,000
10.000- 24,999
25,000 - 49,999
" 50.000- 99,999
I 100.000-149,999
| 150,000 +
U.S. Department of Agriculture. National Agricultural Statistics Ser
Source: NASS, 2010b.
Figure 3-5: Planted Soybean Acres by County
There is some concern that the demand for corn and soybeans as biofuel feedstocks may
lead to high prices of these commodities, inducing farmers with land currently enrolled in
USDA's CRP to return to intensive agricultural production (e.g., Secchi et al., 2009). The CRP
provides farmers with financial incentives to set aside a certain portion of their cropland in order
to conserve or improve wildlife habitat, reduce erosion, protect water quality, and support other
environmental goals. Biomass produced from the cultivation and harvesting of corn, corn stover,
or soybeans on CRP lands is considered a renewable source of energy as defined in RFS2. The
Food, Conservation, and Energy Act of 2008 (known as the Farm Bill) capped CRP acreage at
32 million acres, reducing enrollment by 7.2 million acres from the 2002 Farm Bill with the
potential for making more acreage available for the production of row crops (Figure 3-1).
Historically, land entering and exiting the CRP program has been more vulnerable to erosion
than other cultivated land, but also less productive (ERS, 2008). So while the conversion of CRP
land to intensive feedstock production is possible, the likelihood of such a land use conversion is
uncertain given practical economic and agronomic considerations.
A recent USDA analysis estimates that in order to meet the volumetric requirements of
RFS2, total cropland will increase 1.6 percent over 2008 baseline conditions by 2015, with corn
acreage expanding 3.5 percent and accounting for most of the overall cropland increase
(Malcolm et al., 2009). While corn acreage is expected to expand in most regions, USDA
estimates that traditional corn-growing areas would likely see the largest increases—up 8.6
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Chapter 3: Environmental Impacts of Specific Feedstocks
percent in the Northern Plains, 1.7 percent in the Corn Belt, and 2.8 percent in Great Lakes
States (Malcolm et al., 2009). Other modeling studies have also projected an increase in the areal
extent of cropland in the United States in response to the global demand for bioenergy (e.g.,
BRDI, 2008; Keeney and Hertel, 2009; Beach and McCarl, 2010; Hertel et al., 2010a, 2010b;
Taheripour et al., 2010). These studies project conversion of pasture and other idle agricultural
lands, as well as forest land, to intensive crop production in response to demand for biomass to
produce ethanol and biodiesel. Not all land converted in these modeling studies is assumed to be
used for biomass production, since the complex economics of agriculture, including future prices
of cellulosic feedstocks, directly and indirectly affect land use changes.
3.2.4. Water Quality
Water quality impacts from increased corn and soybean production for biofuel are caused
by pollution from nutrients, sediment, and pesticides, as well as biological contaminants such as
pathogens that are released when animal manure is applied as fertilizer. Multiple studies examine
corn production scenarios to meet EISA targets and find that increased nitrogen inputs to the
Gulf of Mexico and other U.S. coastal waters are likely, and these inputs can worsen hypoxic
conditions if crops are not grown under improved agricultural conservation practices and
expanded nutrient BMPs (Donner and Kucharik, 2008; Malcolm et al., 2009; Rabalais et al.,
2009).
3.2.4.1. Nutrient Loading
Corn has the highest fertilizer use per acre of any of the biofuel feedstocks, and it
accounts for the largest portion of nitrogen fertilizer use among all feedstocks discussed in this
report (U.S. EPA, 2010a). By one estimate, which surveyed 19 U.S. states, approximately 96
percent of corn acreage received nitrogen fertilizer in 2005, with an average of 138 pounds per
acre (NASS, 2006). A study in Iowa found that each acre of corn requires about 55 pounds of
phosphorus (as P2Os) for optimal production (Iowa State University, 2008). Assuming a yield of
154 bushels per acre (NASS, 2010c) and an ethanol conversion rate of 2.7 gallons per bushel
(Baker and Zahniser, 2006), this results in 0.33 pounds of nitrogen and 0.13 pounds of
phosphorus applied per gallon of ethanol produced. Nitrogen discharged from corn and soybean
crops via runoff, sediment transport, tile/ditch drainage, and subsurface flow averages 24 to 36
percent of the nitrogen applied (and can range from 5 percent in drought years to 80 percent in
flood years) (Dominguez-Faus et al., 2009).
Nutrients are applied to fewer soybean acres than corn and at much lower rates because
soybean is a legume (U.S. EPA, 2010a). Legumes have associations in their roots with bacteria
that can acquire atmospheric nitrogen and convert it into bioavailable forms, reducing the need
for external addition of nitrogen fertilizer. However, losses of nitrogen and phosphorus from
soybeans can occur at quantities that can degrade water quality (Dinnes et al., 2002; Randall et
al., 1997). In 2006, USDA's NASS estimated that nitrogen and phosphorus fertilizers were
applied to 18 percent and 23 percent of soybean acreage, respectively, with an average of 16
pounds of nitrogen and 46 pounds of phosphate applied per acre fertilized (NASS, 2007). The
quantity of nitrogen fertilizer applied to soybean fields ranged from 0 to 20 pounds per acre,
while the quantity of phosphate ranged from 0 to 80 pounds per acre. As with corn, the
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Chapter 3: Environmental Impacts of Specific Feedstocks
conversion of idled acreage to soybeans is estimated to result in losses of nitrogen and
phosphorus from the soil through cultivation (Simpson et al., 2008).
Corn requires less fertilizer when grown in rotation with soybeans. Therefore, crop
rotation provides an effective strategy for reducing the amount of fertilizer and pesticide applied
to fields, and therefore could decrease runoff and leaching of the pollutants to water. Some
studies of nitrate leaching from corn-soybean rotation cropping systems are inconclusive about
whether these systems increase or decrease leaching rates compared to continuous corn systems
(Klocke et al., 1999; Zhu and Fox, 2003). However, a more recent study estimated that only 2 to
40 percent of the total nitrogen leached from fields planted alternately with corn and soybeans
came from the fields when they were planted with soybeans (Powers, 2005). This implies that
most of the nitrogen leaching was due to corn production. In general, the total amount of
nitrogen lost from corn fields tends to be higher than losses from soybean fields (Powers, 2005).
However, it is important to consider several factors that cause variability in leaching rates for
both corn and soybeans, including geography, soil type, hydrology, and tillage methods (Powers,
2005).
The removal of corn stover could lead to loss of soil surface cover if Natural Resources
Conservation Service (NRCS) guidelines are not followed, thereby increasing runoff of nitrogen
and phosphorus to surface waters including wetlands (Kim and Dale, 2005). Even partial
removal of corn stover can result in nutrient losses to water due to increased runoff (Kim and
Dale, 2005; Lai, 2004). In addition, corn stover removal can lead to the loss of soil nutrients
needed for corn growth, and higher fertilizer rates are likely to be required to sustain crop
productivity, increasing the likelihood of increased runoff and transport of nonpoint-source
pollutants (Blanco-Canqui and Lai, 2009a, 2009b).
Nutrients—Surface Water Impacts
Increased production of row crops, especially corn due to biofuel demand, will likely
increase nitrogen and phosphorus loading to surface waters (Malcolm et al., 2009). Excessive
levels of nutrients in a body of water often cause accelerated algae growth, reducing oxygen
levels and light penetration. Low dissolved oxygen (i.e., hypoxia) can kill many organisms,
reducing population abundances and overall species diversity in the affected area (Pollock et al.,
2007; Breitburg et al., 2009; Levin et al., 2009). This nutrient enrichment (eutrophication) can
cause serious deterioration of both coastal and inland water resources. According to a 2008
report by the National Research Council, excess nutrients and sediment from the high corn-
producing Midwest are the primary sources of water quality degradation in the Mississippi River
basin and the Gulf of Mexico (NRC, 2008). Further, the National Summary of Impaired Waters
(U.S. EPA, 2010b)n documented that in 2008, nationwide, approximately 50 percent of the 3.5
million miles of stream and rivers and 66 percent of the over 41 million acres of lakes and
reservoirs in the United States were impaired due to nutrient enrichment. Increased corn and
soybean production for biofuels could exacerbate this situation due to the nutrients from
11 Numbers in text were calculated by summing miles/acres reported by each state in their 305(b) assessments as
impaired by "nutrients"; "ammonia, un-ionized"; "nitrogen, total"; "nutrient/eutrophication"; "phosphorus, total";
"ammonia, total"; "nitrogen, nitrate"; and "ammonia."
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Chapter 3: Environmental Impacts of Specific Feedstocks
additional fertilizer used for increased acreage or switching to continuous corn, or from increased
extent and density of subsurface tile drainage. A report by Donner and Kucharik (2008) predicts
that the average annual flux of dissolved inorganic nitrogen (DIN) to the Gulf of Mexico could
increase by 10 to 18 percent if EISA targets for non-advanced biofuels are met through either
greater CRP to corn conversion or greater soybeans to corn conversion than the 2007 baseline;
DIN flux would increase to 34 percent if all 36 billion gallons come from corn. This is in
contrast with a USDA report that predicts an increase 1.8 percent nationally of nitrogen runoff
into estuaries by 2015 due to agricultural acreage expansion and intensification (Malcolm et al.,
2009). Despite the predicted increases in nutrient influx associated with row crops, there are
ongoing efforts to address hypoxia in the Gulf of Mexico. These include the work of the
Mississippi Basin/Gulf of Mexico Task Force and the USDA's Mississippi River Basin Healthy
Watersheds Initiative (MRBI). The Task Force established a 30 percent reduction goal in nutrient
loading to the Gulf to reduce the hypoxic zone to less than 5000 km2 (Mississippi River/Gulf of
Mexico Watershed Nutrient Task Force, 2008). The MRBI is a multiyear program that began in
2009. It is managed by NRCS and is intended to reduce the nutrient loading into the Gulf of
Mexico. Twelve states are receiving support to adopt or expand conservation efforts in priority
watersheds (NRCS, 201 Ob).
Mitigating the loss of nitrogen and other nutrients to water bodies is a research priority
for USDA. Since drainage systems are a key conduit for nutrient loading, new research is
focusing on alternative surface and subsurface drainage solutions. Subsurface tiles/pipes or
artificial ditches are drainage systems that remove water from the soil subsurface to allow for
crops to be planted. While these systems can move water from soils to surface water or wells,
they can also quickly transport nutrients and pesticide runoff from fields without any of the
attenuation that would occur if these contaminants were moving through wetlands or soils (U.S.
EPA, 2010a). An interagency Agricultural Drainage Management Systems Task Force, formed
in 2003 and recently expanded, is working to reduce the loss of nitrogen and phosphorus from
agricultural lands through drainage water management (CENR, 2010).
One emerging conservation practice that addresses water quality degradation is the
creation of wetlands on the perimeter of fields in order to receive surface runoff and filter out
nutrients prior to the runoffs discharge into streams and rivers. Surface water runoff control, a
set of conservation practices used to stop water erosion, reduces the overland losses of nutrients
to the surrounding environment, but increases infiltration and loss of soluble nitrogen and
phosphorus. A third strategy, lowering the water table during planting and harvesting, has been
predicted to lower nitrogen losses in the Chesapeake watershed by 40 percent (CENR, 2010).
The use of cover crops has also been shown to reduce nitrogen loss from fields (Dinnes et al.,
2002). Other strategies, such as planting perennial grasses over subsurface tile drains or placing
wood chips in drainage ditches, are also being explored. Implementing strategies such as these
on agricultural lands that contribute a disproportionate share of nitrogen loads will maximize the
environmental benefit of their application (CENR, 2010).
Significant opportunities exist for further increasing efficient use of nitrogen simply by
increasing the number of growers who follow all nutrient BMPs. For instance, NRCS found that
only about 38 percent of all cultivated cropland acres in the upper Mississippi River basin are
already under the complete suite of nutrient management practices: proper source, rate, timing,
and place of application (NRCS, 2010a). Given the extensive focus on the nutrient management
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Chapter 3: Environmental Impacts of Specific Feedstocks
issue at USDA and within the agricultural community, the proportion of acres benefitting from
such nutrient management practices could increase.
Nutrients—Coastal Waters Impacts
Nutrient enrichment is a major concern for coastal waters across the United States,
including the Gulf of Mexico, Chesapeake Bay, other estuaries, and the Great Lakes. For
example, almost 15 percent of the coastal waters in the Gulf of Mexico and Northeast have poor
water quality as measured by nutrient concentrations, extent of hypoxia, and water clarity (U.S.
EPA, 2008b). The number of U.S. coastal and estuarine ecosystems documented as experiencing
hypoxia increased from 12 in 1960 to over 300 in 2008 (out of 647 coastal ecosystems analyzed)
(see Figure 3-6) (CENR, 2010). While these impacts are due to a number of types of nutrient
inputs, such as lawn fertilizers, other agricultural uses, atmospheric deposition, and wastewater
discharges, increased corn and soybean production for biofuel will likely increase nutrient
loading in those watersheds where increased production occurs (SAB, 2007; Rabalais et al., 2007
as cited in CENR, 2010).
..!•«.
Ip*,] MO
-
Up to 2008
Note: Map does not display one hypoxic system in Alaska and one in Hawaii.
Source: CENR, 2010.
Figure 3-6: Change in Number of U.S. Coastal Areas Experiencing Hypoxia
from 1960 to 2008
Hypoxia in the Gulf of Mexico is a long-standing environmental and economic issue that
threatens commercial and recreational fisheries in the Gulf (U.S. EPA, 2010a). The primary
cause of hypoxia in the Gulf of Mexico is excess nitrogen and phosphorus loadings from the
Upper Midwest flowing into the Mississippi River, suggesting that increased corn and soybean
production may exacerbate the problem (U.S. EPA, 2010a). U.S. Geological Survey (USGS)
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Chapter 3: Environmental Impacts of Specific Feedstocks
1 9
SPARROW modeling of the sources of nutrient loadings to the Gulf of Mexico estimated that
agricultural sources contributed more than 70 percent of the delivered nitrogen and phosphorus
to the Gulf of Mexico (Alexander et al., 2008). Corn and soybean production accounted for 52
percent of nitrogen delivery and 25 percent of phosphorus delivery. Modeling of the upper
Mississippi River basin using SWAT13 modeling indicated that, on average, it contributes 43
percent of the nitrogen load to the Gulf of Mexico, and 26 percent of the phosphorus load (SAB,
2007). One study estimated that corn production contributes between 60 and 99 percent of the
total nitrogen load to the Mississippi River from eastern Iowa watersheds (Powers, 2007). Other
studies have also determined that the majority of nitrate in the Mississippi River originates in the
Corn Belt (Donner et al., 2004; Goolsby et al., 1999).
Nitrogen from fertilizers can also volatilize and then return to waters through atmospheric
wet or dry deposition of either reduced or oxidized forms (e.g., NHX, NOy). Atmospheric
nitrogen from all sources, including power plant emissions, is estimated to contribute up to
approximately 27 percent of the nitrogen loading to both the Gulf of Mexico (Alexander et al.,
2008), and to the Chesapeake Bay (Paerl et al., 2002).
A USD A study projects that reaching 15 billion gallons per year of ethanol from corn
starch (i.e., not including stover) will result in an average 1.7 percent increase (over the 2008
baseline used in the USD A report) in nitrogen loads to surface water nationally by 2015, with the
greatest contributions in nitrogen load occurring in the Corn Belt (1.3 percent) and Northern
Plains (3.5 percent) (Malcolm et al., 2009). Another study used the Terrestrial Hydrology Model
with Biochemistry to generate several corn-based scenarios to reach the 2022 non-advanced
biofuels target. In these scenarios, dissolved inorganic nitrogen exported by the Mississippi and
Atchafalaya Rivers increases 10 to 18 percent, which is 39 to 43 percent greater than the federal
hypoxia reduction target established for the Gulf of Mexico (Donner and Kucharik, 2008).
Ecological features such as wetlands and riparian buffers play an important role in
absorbing nutrients. Conserving wetlands where they exist, or creating artificial vegetated
riparian buffers between waters and croplands, is a way to mitigate the impacts of nutrient
loading. Riparian buffers and filter strips prevent potential pollutants in agricultural runoff
(sediment, nutrients, pesticides, pathogens) from reaching surface waters. While the
effectiveness of these buffers can vary depending on many factors, including slope, width,
vegetation used, and how well they are maintained, studies have shown that they can remove up
12 SPARROW (SPAtially Referenced Regressions On Watershed) is a watershed model developed by USGS
relating water quality measurements at monitoring stations to other watershed attributes. The model estimates
nitrogen and phosphorus entering a stream per acre of land, and evaluates the contributions of nutrient sources and
watershed properties that control nutrient transport.
13 The Soil and Water Assessment Tool (SWAT) is a public domain model jointly developed by USDA Agricultural
Research Service and Texas A&M University System. SWAT is a river basin-scale model to simulate the quality
and quantity of surface and ground water and predict the environmental impact of land management practices on
different soil patterns and land use patterns.
> 1O
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Chapter 3: Environmental Impacts of Specific Feedstocks
to 78 percent of phosphorus, 76 percent of nitrogen, and 89 percent of total suspended solids
(Schwer and Clausen, 1989; Dosskey, 2001; Richardson et al., 2008).14
Nutrients—Ground Water Impacts
Ground water can be used for public and private drinking water supplies, and fertilizers
can increase the concentration of nitrate in ground water wells, especially shallow wells (less
than 200 feet deep). USGS sampled 495 wells in 24 well networks across the United States in
predominantly agricultural areas from 1988 to 2004 and found significant changes in
concentrations of nitrate in eight of the well networks. In seven of those eight networks, USGS
found significant increases in nitrate concentrations; in three of those seven, nitrate
concentrations exceeded the federal drinking water standards of 10 mg/L of nitrate-nitrogen
(Rupert, 2008). Increased corn production for biofuels could worsen the problem of
contaminated well water because of additional nitrogen inputs from fertilizer used to grow more
corn. USD A projects that reaching 15 billion gallons per year of ethanol from corn will result in
a 2.8 percent increase in nitrogen leaching to ground water, with the greatest increases occurring
in the Great Lakes states and the Southeast; this increase occurs with a 1.6 percent increase in
corn acreage (Malcolm et al., 2009). Similar estimates for soybean production were not
identified.
Fertilizer application management strategies aim to reduce nitrogen leaching by
maximizing the efficiency of applied fertilizer. Such strategies focus on collecting precise
information on soil nutrient content in order to better inform application rates. USDA reports that
phosphorus accumulation on farms has reached levels that often exceed crop needs (ARS, 2003).
Better information on these conditions could help reduce nutrient runoff that leads to
eutrophi cation.
3.2.4.2. Sediment
Nutrients and sediment are the two major water quality problems in the United States,
and much attention has been focused on these issues in the Mississippi River basin and the Gulf
of Mexico (NRC, 2008). As modeled in a 2010 NRCS study, cropped areas in the upper
Mississippi River basin lose one ton of sediment per acre per year, with 15 percent of cropped
acres experiencing more than 4 tons of sediment lost per acre in one or more years (NRCS,
2010a). The National Summary of Impaired Waters stated that in 2008 over 70,000 miles of
streams and rivers and over 1.2 million acres of lakes and reservoirs in Mississippi River basin
states are impaired because of sediments or turbidity (U.S. EPA, 2010b).15 Nelson et al. (2006)
reported that row crops, such as corn and soybean, result in higher erosion rates and sediment
loads to surface waters, including wetlands, than non-row crops that might be used as biofuel
feedstock, such as grasses. Sedimentation rates in agricultural wetlands can be higher than in
natural grassland landscapes; increased sedimentation may, depending on sediment depths, cover
14 See also
http://cfjpub.epa. gov/npdes/stormwater/menuofbmps/index.cfm?action=factsheet_results&view=specific&bmp=82.
15
Numbers in text were calculated by summing miles/acres reported by each state in their 305(b) assessments as
impaired by "sedimentation/siltation" or "turbidity."
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Chapter 3: Environmental Impacts of Specific Feedstocks
viable seeds sufficiently to prevent germination (Gleason et al., 2003). Studies evaluating the
impacts of RFS2 over the next decade have provided estimates for the increases in sediment
loads. A study conducted for EPA estimated that annual sediment loads to the Mississippi River
from the upper Mississippi River basin would increase by only 0.52 percent between 2005 and
2015 and 0.30 percent by 2022 (assuming corn stover remained on the field following harvest)
(Aqua Terra, 2010). A USDA study estimates that nationally, sediment loads in 2015 will be 1.6
percent greater with implementation of RFS2 than without (assuming ethanol production from
corn starch only) (Malcolm et al., 2009).
Removal of corn stover from fields for use in biofuel production could increase sediment
yield to surface waters and wetlands, but erosion rates can be highly variable depending on soil
type, slope, management of fields, and the proportion of stover harvested (Cruse and Herndl,
2009; Kim and Dale, 2005). Results of SWAT modeling of the upper Mississippi River basin
(Aqua Terra, 2010) indicated that leaving corn stover on fields helps reduce soil erosion and
sediment transport, even when the amount of land in corn production increases. However, the
amount of soil erosion that agricultural cropland experiences is a function of many factors,
including not only residue left on the field, but also field operations (field preparation, tillage,
etc.) in preparation for the next crop, timing of field operations, and other site-specific factors
noted above (U.S. EPA, 2010a).
Conservation tillage practices, including no-till, strip-till, ridge-till, and mulch-till,16 can
reduce erosion by leaving at least 30 percent of the ground covered by crop residue and by
limiting soil disturbance. According to USDA, 41 percent of planted acreage in the United States
uses conservation tillage as a mitigation strategy (ARS, 2006). In 2002, the USDA Agricultural
Research Service (ARS) studied the effect of ridge tillage on Northern Corn Belt plantations.
The study showed that ridge tillage not only reduced erosion and sediment loading but also
increased profitability, reduced fuel and labor use, and reduced economic risk relative to
conventional tillage for a corn and soybean rotation (ARS, 2006). Additionally, these alternative
tillage approaches can reduce trips across the field, lowering fuel use and improving the energy
balance of the resulting biofuel. The use of conservation tillage, in combination with BMPs such
as cover crops, may partially compensate for the increase in erosion potential caused by cover
stover removal (Blanco-Canqui and Lai, 2009b). Depending on the soil type, these practices may
allow a percentage of stover to be harvested sustainably (Blanco-Canqui and Lai, 2009b).
3.2.4.3. Pesticides
According to the National Summary of Impaired Waters (i.e., waters that do not meet the
water quality standards) (U.S. EPA, 2009a, 2010c), pesticides were a cause of impairment for
approximately 3.1 percent (372,009 acres) of threatened or impaired lakes, reservoirs and ponds
and 3.5 percent (16,980 miles) of threatened or impaired streams and rivers in the U.S. (U.S.
EPA, 201 Ob). Approximately 2 percent of the causes of impaired waters were attributed to
16 No-till refers to the absence of soil tillage to establish a seed bed, meaning the farmer plants the crop directly into
the previous year's crop residue. In strip-till, only the portion of the soil that is to contain the seed row is disturbed.
In ridge-till, plants grow on hills that are the product of cultivation of the previous crop and are not tilled out after
harvest. In mulch-till, plant residues are conserved but a field cultivator or disks are used to till before planting to
partially incorporate the residue into the soil.
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Chapter 3: Environmental Impacts of Specific Feedstocks
pesticides and, of those, over three fourths were attributed to pesticides that are no longer
registered for use by EPA (U.S. EPA, 2010b). Atrazine is a pesticide commonly used in corn
production and lost from agricultural lands in the upper Mississippi River Basin (NRCS, 2010a).
It was cited as a cause for approximately 1 percent of the total number of impaired or threatened
stream and river miles in the U.S. (U.S. EPA, 2010b).
USDA estimates that insecticides were applied to 16 percent of the 2006 soybean-planted
acreage (NASS, 2007). USDA also estimates that herbicides were applied to 98 percent of the
planted soybean acreage in 2006. Soybean production releases less pesticide to surface and
ground water per unit of energy gained than corn agriculture (Hill et al., 2006).
Growing continuous corn (rather than growing it in rotation with other crops) can
increase population densities of pests such as the corn rootworm, resulting in increased pesticide
applications to control these pest species (Whalen and Cissel, 2009) or the introduction of new
varieties of genetically engineered crops (Bates et al., 2005; Glaser and Matten, 2003). A USDA
study projects that cropland dedicated to continuous corn will increase by more than 4 percent
(above a 2008 baseline) by 2015 to reach the target of 15 billion gallons of ethanol per year from
corn (Malcolm et al., 2009).
While effective pest control may be critical to achieving the yield gains that underpin
EISA biofuel projections and targets (Perkins, 2009), there are risks associated with the use of
pesticides. The Federal Insecticide Fungicide and Rodenticide Act (FIFRA) registration process
is intended to minimize these risks. Many factors contribute to the relative risks of pesticides to
the environment, including fate and transport characteristics, method of application, depth to
ground water, and proximity to receiving waters.
Integrated pest management (IPM) practices may help reduce pesticide use by tailoring
treatment to pest infestation cycles, and by more precisely targeting the amount and timing of
applications. IPM focuses on extensive monitoring of pest problems, comprehensive
understanding of the life cycles of pests and their interaction with the environment, and precise
timing of pesticide applications to minimize pesticide use. In addition to providing
environmental benefits of lower pesticide use, IPM often lowers chemical pesticide expenses and
pest damage to crops, as well as preventing the development of pesticide-resistant pests. The use
of cover crops is an IPM practice that can dramatically reduce chemical application and soil
erosion. USDA research in the Midwest in 2006 demonstrated that autumn-planted small grain
cover crops reduced soil erosion, nitrate leaching, and suppressed weeds (Teasdale et al., 2007).
National adoption of IPM strategies varies. Corn and soybean growers reported scouting
for weeds, insects, and diseases on 50 percent of acres or more in 2000, but reported adjusting
planting or harvest dates to manage pests on less than 20 percent of acres (Weibe and Gollehon,
2006).
3.2.4.4. Pathogens and Biological Contaminants
The use of animal manure as a fertilizer has been tied to an increased risk of viruses and
bacteria leaching into the water supply. Pathogens such as Salmonella sp., Campylobacter sp.,
and Clostridium perfringens—along with additives such as livestock antibiotics and hormones—
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Chapter 3: Environmental Impacts of Specific Feedstocks
may be released into surface or ground water when manure is applied to fields (Brooks et al.,
2009; Lee et al., 2007b; Unc and Goss, 2004). The USDA Report to Congress on use of manure
for fertilizer and energy reports that approximately 12 percent of corn and 1 percent of soybeans
are fertilized with manure (MacDonald et al., 2009).
The flow paths by which pathogens can contaminate ground or surface water are the
subject of current research. Transport through soil has been shown to remove harmful bacteria in
some cases, though this may depend on soil characteristics, the hydrologic regime, and the
pathogens in question (Malik et al., 2004; Unc and Goss, 2004). Contamination rates likely are
greater where there is higher runoff relative to infiltration, a high water table, or a direct surface-
ground water connection. Implementation of manure management practices, such as covering or
storage at elevated temperatures before application, can reduce runoff and the presence of
pathogens. In addition, applying manure during times of low runoff potential can reduce the risk
of water contamination (Moore et al., 1995; Guan and Holley, 2003).
3.2.5. Water Quantity
3.2.5.1. Water Use
Agricultural production fundamentally depends on water. In many of the top corn- and
soybean-producing states, agricultural water demand is met by natural rainfall; in other states,
favorable yields are achieved using irrigation. In USDA farm census years between 2002 and
2008, approximately 14 to 15 percent of corn and 7 to 9 percent of soybean acres annually
harvested were irrigated (NASS, 2009a, 2009b). In the Great Plains and the Midwest, where the
majority of corn and soybean production takes place, farmers who irrigate rely largely on ground
water (Kenny et al., 2009); for instance, in Nebraska in 2008, 95 percent of irrigated corn
received ground water from wells (NASS, 2009b). When used to enhance yields, crop irrigation
is by far the most significant use of water in the ethanol and biodiesel supply chains (see Figure
2-2), and it tends to be much higher than water use for most other non-renewable forms of
energy on an energy content basis (King and Webber, 2008; Gerbens-Leenes et al., 2009; Wu et
al., 2009).
Geography and the type of land/crop conversion will determine water use impacts from
increased corn or soybean production to meet biofuel demands. Water use could increase if land
in pasture or other low- or non-irrigated uses is converted to irrigated row crop production,
especially corn in places like the Great Plains, where water demand for irrigation is even higher
than for soybeans on a per area basis (NRC, 2008; NASS, 2009b). In predominantly rain-fed
locations like much of the Midwest, water supply impacts are less likely to occur. Future
assessment of biofuel feedstocks will also need to consider restrictions on water use due to
competing demands for water resources (Berndes, 2002).
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Chapter 3: Environmental Impacts of Specific Feedstocks
Water Use: Irrigation vs. Evapotranspiration
The agricultural water cycle involves inputs and outputs of water. Water enters into agricultural
fields via precipitation and/or irrigation from ground or surface water sources. It exits via surface runoff,
infiltration into soil layers below the rooting zone, and ET. ET is the combination of evaporation from the
surface of the ground and transpiration. Transpiration is the process by which plants take up water from the
soil and release water vapor through pores, called stomata, in their leaves.
Crop water use and its implications for water availability for other human and ecological demands
can be understood by examining various parts of the agricultural water cycle, including irrigation and ET.
Some crops in some regions require no irrigation to achieve favorable yields. However, when water is
withdrawn for irrigation, this results in at least the temporary and sometimes functionally permanent
reduction in the availability of water for other uses. As water is being withdrawn and applied, all of it is
temporarily unavailable for other uses. A fraction of irrigation water may run off into surface water bodies or
infiltrate into the soil or shallow groundwater aquifers, and if of sufficient quality, it becomes available once
more for human surface withdrawal or ecological communities on a relatively short time scale. When
irrigation water is pumped from deep regional aquifers, it may not return to (or recharge) those aquifers for
centuries, which restricts that supply of water to meet other demands well into the future. Another important
facet of the agricultural water cycle is the amount of water that exits fields via ET. The total amount of water
that crops and other vegetation evapotranspire depends on many factors, including the species or variety of
plants, cultivation and/or irrigation practices, weather, and soil properties. Consequently, calculating changes
in ET attributable to a shifting biofuels landscape and estimating their magnitude and impact requires
accounting for these factors. For example, Hickman et al. (2010) show that corn evapotranspires less water
over its growing season than switchgrass and Giant Miscanthus, though whether this is an overall trend
would have to be evaluated in combination with studies of other cultivars, seasons and locations. Water that
is evapotranspired is lost to the atmosphere, where it is unavailable for human withdrawal or ecological use
and where it can affect regional climate trends and feedbacks (e.g., VanLoocke et al., 2010). Therefore,
measuring both the water withdrawn for irrigation of biofuel feedstocks and their water loss to the
atmosphere are important to understand the influence of feedstock production on water availability, and
some studies seek to reflect this (e.g., Dominguez-Faus et al., 2009).
In some parts of the country, water demands for corn are met by natural rainfall, while in
other places supplemental irrigation is required to achieve favorable yields. For instance, in Iowa
in 2007, less than 1 percent of the more than 14 million acres planted in corn was irrigated. In
contrast, approximately 60 percent of Nebraska's 9.5 million acres of corn was irrigated in the
same year (NASS, 2009a). On fields that are irrigated, rates of application on a per area basis
also vary from place to place. In 2008 in the United States overall, an average of 1 acre-foot
(325,851 gallons) of water was used on an acre of irrigated corn (NASS, 2009b). In Iowa and
Illinois, the rate of corn irrigation was half that, while in Nebraska the rate was 0.8 acre-feet
(260,680 gallons) per irrigated acre. Above-average rates of irrigation are generally found in the
western United States (NASS, 2009b).
Several studies have attempted to calculate the amount of irrigation used to produce corn
ethanol on a per gallon basis. Wu et al. (2009) averaged irrigation water used over all irrigated
and non-irrigated acres on a regional scale and found approximately 7 gallons of water were
required per gallon of ethanol in states like Iowa and Illinois, and over 300 gallons of
water/gallon ethanol were required in Nebraska and the Dakotas. Chiu et al. (2009), using similar
methodology, were largely in agreement. Another study, which focused on irrigated acres only,
found that up to 1,000 gallons of water were required per gallon of irrigated ethanol in the Great
Plains (Dominguez-Faus et al., 2009). A handful of studies have also accounted for water use via
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Chapter 3: Environmental Impacts of Specific Feedstocks
crop evapotranspiration (ET) (see the text box) to produce a "water footprint" of ethanol
production in the United States (e.g., Mubako and Lant, 2008; Dominguez-Faus et al., 2009).
Estimates of water use per gallon of ethanol tend to be higher in these calculations, because both
irrigated and non-irrigated corn loses water to the atmosphere via ET. Taking into account the
volume of corn starch ethanol produced per state and the area of corn currently needed as
feedstock to achieve those volumes, as well as irrigation practices, total water use for corn
ethanol can add up to very large amounts. Chiu et al. (2009) suggest approximately 5 billion
gallons of irrigation water could be used in a single season in places like Iowa and Illinois versus
300 billion gallons in Nebraska.
The presence of a crop residue layer, such as corn stover, shields the soil surface,
reducing evaporation while also maintaining soil organic matter, a critical component of the
water-holding capacity of the soil. The harvesting of corn stover is likely to have little or
negligible impact on water use above and beyond corn cultivation if undertaken in the most
productive corn-growing regions of the United States, where corn stover is not functionally
necessary for retention of soil moisture. However, under warmer conditions, corn growth can be
enhanced by higher available water resulting from maintaining crop residues (Blanco-Canqui
and Lai, 2009b). If corn stover is removed from dry corn cultivation areas with supplemental
irrigation (e.g., in states like Nebraska), loss of soil moisture that would have otherwise been
retained by corn stover cover could necessitate additional irrigation. The opposite, however, has
been demonstrated in colder, wetter soils where heavy crop residue layers can delay corn
emergence and lower crop yields (Liu et al., 2004). In such cases and locations, it is
advantageous to remove at least some of the corn stover.
Water for soybean cultivation usually comes from natural precipitation and sometimes
irrigation. In the leading soybean-producing state of Iowa in 2007, 8.6 million acres of soybeans
were grown, of which less than 1 percent was irrigated (NASS, 2009a). Nebraska, on the other
hand, grew 3.8 million acres of soybeans in 2007, of which over 40 percent was irrigated (NASS,
2009a). On soybean fields that were irrigated in 2008, rates of application on a per area basis
averaged 0.7 acre-feet (228,095 gallons) in the United States overall (NASS, 2009b). In Iowa,
Illinois, and Nebraska the rates of soybean irrigation were 0.4, 0.5, and 0.6 acre-feet,
respectively, while in Arkansas the rate was above the national average at 0.9 acre-feet (293,265
gallons) of water per irrigated acre (NASS, 2009b).
Focusing solely on irrigated soybeans, Department of Energy (DOE) (2006) estimated an
average nationwide rate of about 6,000 gallons of irrigation water to produce a gallon of
biodiesel. A volume of biodiesel with the energy equivalent of a gallon of ethanol (which is less
energy-dense than biodiesel), would require about 4,000 gallons of irrigation. A more recent
study brings the irrigation volume in the range of 1,500 to 3,000 gallons of water per volume of
biodiesel equivalent to the energy in a gallon of ethanol (Dominguez-Faus et al., 2009). It is
important to note that these rates do not account for the more than 90 percent of soybeans that
are grown without irrigation. An average value based on irrigated and non-irrigated soybean
acres would likely be much smaller, unless it also included ET, which has been estimated at
about 2,000 gallons or more per volume of biodiesel equivalent to the energy in a gallon of
ethanol in the United States (Dominguez-Faus et al., 2009; Gerbens-Leenes et al., 2009).
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.2.5.2. Water Availability
Because agriculture accounts for such a large share of water use in the United States (37
percent of withdrawals nationwide in 2005, and a much larger percentage in some parts of the
country, according to Kenny et al., 2009), changes in agricultural production could impact future
water availability. For example, land conversion to irrigated corn from typically non-irrigated
pasture, marginal, or CRP land could create more demand for water, adding to existing water
constraints and potentially creating new ones in places like the Great Plains states.
To a large extent, the current capacity to produce biodiesel from soybeans resides in
states with rain-fed soybean cultivation. Such strategic siting of biodiesel production facilities
minimizes both demands for irrigation water for biodiesel feedstock and potential conflicts over
water required for other purposes, such as power generation, public water use, ecosystems, and
recreation. However, if biodiesel production develops in places requiring greater soybean
irrigation such as the Great Plains, water availability could be reduced. This is especially true if
irrigated soybean cultivation replaces other low or non-irrigated land uses. In the case of both
corn and soybeans, because the vast majority of irrigation withdrawals in the Great Plains are
from ground water wells (NASS, 2009b) that tap underground aquifers like the High Plains
aquifer, ground water availability is likely to be affected more directly than surface water.
Both surface water and ground water withdrawals can negatively impact aquatic life.
Surface water withdrawals can reduce flood flows (or peak flow regimes), as well as reduce total
flow (or discharge) during summer months when irrigation requirements are high and surface
water levels are low (Poff and Zimmerman, 2010). Ground water availability over the past
several decades has been notably diminished in some places in the United States by withdrawals
for irrigation (Reilly et al., 2008). The water level in the southern portion of the High Plains
aquifer, in particular, has dropped 37 feet since extensive irrigation development in Texas in the
1930s and 1940s; recent annual water level declines in the states overlying the High Plains
aquifer (e.g., Kansas, Nebraska, South Dakota, Oklahoma) are modest in comparison, but steady
(McGuire, 2009). The consequences of ground water withdrawals that exceed recharge rates
could include reduced water quality, prohibitive increases in the costs of pumping, reduced
surface water levels through hydrological connections, and subsidence (Reilly et al., 2008).
Withdrawals from hydrologically connected aquifers can lower base flow to rivers and streams
that depend on ground water to maintain year-round stream flow. In some areas, stream flow has
been reduced to zero because of ground water depletion, but in other areas, minimum stream
flow during the summer has been sustained because of irrigation return flow to streams
(Bartolino and Cunningham, 2003).
Options to mitigate the challenges outlined above do exist. Locating corn ethanol and
soybean biodiesel production in regions that do not require irrigation is one option, although it
may lead to displacement of row crop acreage for food or feed to more irrigation-intensive
regions. Irrigation in locations that require it could be minimized by using crop varieties bred for
high water use efficiency and/or drought tolerance or by installing more efficient irrigation
delivery. Such strategies over the past decade have allowed nationwide irrigation delivery per
acre to remain relatively flat for both corn and soybeans at the same time yields per acre have
risen (Keystone Alliance, 2009). In the upper Mississippi River basin, specifically, the USDA
estimates that the 2 percent of land that does receive irrigation has achieved 46 percent reduction
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Chapter 3: Environmental Impacts of Specific Feedstocks
in irrigation per acre, resulting from more efficient irrigation delivery and application techniques
(NRCS, 2010a). It may also be possible to use recycled or reclaimed water to irrigate, thus
reducing reliance on freshwater withdrawals (NRC, 2008).
3.2.6. Soil Quality
3.2.6.1. Soil Erosion
Soil erosion can have substantial negative effects on soil quality by preferentially
removing the finest, uppermost soil particles, which are higher in organic matter, plant nutrients,
and water-holding capacity than the remaining soil. The soil erosion impact of growing corn or
soybeans for biofuel will vary, largely depending on the particular land use/land cover change
and tillage practices. Conversion of uncultivated land, such as CRP acreage or pasture, to corn or
soybeans for biofuels is the land use change scenario most likely to increase erosion and
sedimentation. The USDA CEAP report on the upper Mississippi River basin found that for land
in long-term conserving cover, like CRP, soil erosion and sediment loss were almost completely
eliminated (NRCS, 2010a). Moreover, CRP acreage in riparian areas slows runoff, promoting the
retention of sediment, nutrients, and other chemicals. The USDA Farm Service Agency (FSA)
estimated that, in 2008, CRP land collectively prevented 445 million tons of soil from eroding
(FSA, 2009). The soil-erosion effects of converting former or current pasture land to corn will
vary depending on prior erosion rates. Pasture land in the United States' Southern Piedmont
region, for example, can exhibit soil stability equal to forested or conservation-tilled land
(Franzluebbers et al., 2000); converting this type of land to conventional corn production will
increase soil erosion. In contrast, if much of the increase in corn or soybean production comes
from a shift from other crops, the effect on soil erosion is likely to be much smaller. There have
been substantial improvements over the last two decades in corn and soybean soil loss indicators
(Keystone Alliance, 2009). By 2015, USDA predicts an increase in sheet erosion by 1.7 percent
(in accord with the 1.6 percent increase in acreage above the 2008 baseline), and an increase in
wind erosion by 0.7 percent. There is variation across regions in magnitude and whether the
changes are driven by land use or management changes (Malcolm et al., 2009). Allocation of a
higher percentage of corn or soybeans for biofuel production from land already in corn and
soybean production should not alter soil erosion rates.
Tillage practices can mitigate soil erosion on current agricultural lands. Conventional
tilling17 breaks up soil aggregates, increasing erosion by wind and water (Lai, 2003). In contrast,
conservation tillage—defined as practices that maintain at least 30 percent of the ground covered
by crop residue (Lai, 1997)—can considerably reduce soil erosion (Cassel et al., 1995; Shipitalo
and Edwards, 1998). No-till agriculture, a type of conservation tillage, disturbs the soil only
marginally by cutting a narrow planting slit. According to an NRCS report, conservation tillage
is practiced on 91 percent of all crop acreage in the upper Mississippi River basin, with 28
percent in no-till and only 5 percent in continuous conventional tillage (NRCS, 2010a).
Conservation tillage practices may also partially mitigate the impact of converting CRP acreage
to biofuel corn production (Follett et al., 2009). A majority of CRP acreage in areas of the
Midwest is classified as highly erodible land, where tillage practices are influenced by the
17 Defined as any tillage practice that leaves less than 15 percent of crop residues on the soil surface after planting.
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Chapter 3: Environmental Impacts of Specific Feedstocks
conservation compliance provisions of the 1985 Food Security Act (Secchi et al., 2009). For
example, corn-soybean rotations with no-till cultivation can be required in order to maintain
eligibility for certain USDA benefits and programs (Secchi et al., 2009).
Finally, removal of corn stover beyond a certain threshold may substantially increase soil
erosion rates. Crop residues remaining after harvest reduce erosion both directly through the
physical shielding of soil particles and indirectly through the addition of organic matter,
promoting aggregation. Thus, stover removal is likely to be most problematic on erosion-prone
soils. Due to this and cost concerns, a recent study suggested that only approximately 30 percent
1 &
of corn stover would be available for sustainable harvesting in the United States if erosion rates
were to be kept lower than soil loss tolerances (T-values) as defined by the USDA NRCS
(Graham et al., 2007). Because of wind erosion, the potential for corn stover removal in the
western plains states may be particularly limited (Graham et al., 2007). Site cultivation practices
may partially compensate for the effects of residue removal. If no-till agriculture were
universally adopted, sustainably harvested corn stover supplies could increase from
approximately 30 to an estimated 50 percent (Graham et al., 2007). Yet, even with no-till
management, corn stover removal rates at or higher than 25 to 50 percent, depending on location,
have been shown to increase erosion potential (Blanco-Canqui and Lai, 2009a).
3.2.6.2. Soil Organic Matter
Soil organic matter is critical to soil quality because it retains plant nutrients and water,
facilitates carbon sequestration, promotes soil structure, and reduces erosion. The impact of corn
and soybean production for biofuel on soil organic matter will depend on the land use history of
the cultivated acreage. Corn production will negatively impact soil quality on acreage where
organic matter has accumulated over time—for example, grasslands. Placing previously
undisturbed soils into cultivation can result in carbon losses of 20 to 40 percent during the first
five to 20 years of continuous conventional tillage (Davidson and Ackerman, 1993). Reduced
losses would be expected in cases where conservation tillage is used (Follett et al., 2009) or from
soils already depleted in organic matter. Increased corn or soybean production on currently
cultivated land will have a smaller effect on soil organic matter, particularly where substantial
amounts of crop residues are returned to the soil or a cover crop is used (Drinkwater et al., 1998;
Lai, 2003; Adviento-Borbe et al., 2007). While soil quality degrades overtime, yields and
production can be maintained by the use of fertilizers, both commercial and organic.
Tillage practices may influence soil organic carbon levels as well. Meta-analyses have
concluded that no-till or reduced tillage increases soil carbon levels (West and Post, 2002; Ogle
et al., 2005). However, recent studies—more limited in scope—have suggested that no-till
practices may increase carbon in the upper layers of the soil, but decrease amounts at lower
depths compared to conventional tillage, with no difference in overall carbon storage (Baker et
al., 2007; Blanco-Canqui and Lai, 2008). More studies of tillage effects on soil carbon deeper in
the soil profile are needed. Determining the effect of tillage on soil carbon can be especially
important for greenhouse gas modeling. For example, Kim et al. (2009) estimated that grassland
18 It should be noted that the removal of crop residues by percent mass is not the same as by percent soil coverage.
All the percentages from the studies discussed here are by percent mass, unless otherwise noted.
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Chapter 3: Environmental Impacts of Specific Feedstocks
conversion to corn for ethanol production would take 18 years to provide greenhouse gas
benefits with conventional tillage, whereas with no-till it would take only four years.
The amount of corn stover needed to maintain soil organic matter levels is likely higher
than that needed to control erosion (Wilhelm et al., 2007). Thus, the 30 percent harvesting
estimate by Graham et al. (2007) may not leave enough stover on the field to maintain soil
organic matter. Stover removal rates of 25 to 75 percent have been shown to decrease soil
organic matter across several soil types even under no-till management (Blanco-Canqui and Lai,
2009a). There is concern that high stover removal rates may decrease soil carbon sequestration
and concomitantly lower crop yields (Karlen et al., 2009). Corn stover removal at about 50
percent on a non-irrigated field in Nebraska led to significant declines in both grain and stover
production (Varvel et al., 2008). Whatever the removal rate for a particular site, it has been
recommended that soil erosion and organic matter content should be periodically monitored to
allow stover removal rates to be adjusted accordingly (Andrews, 2006). The effects of crop
residue removals on crop yields have been shown to be highly variable depending on soil type,
climate, topography, and tillage management, among other characteristics (Blanco-Canqui and
Lai, 2009b). Since the effects of management practices on soil organic matter often take many
years to detect, predicting the impacts of different levels of residue removal on soils will take a
combination of both modeling and monitoring of long-term, residue-removal field trials.
3.2.7. Air Quality
Air quality impacts during cultivation and harvesting of corn and soybeans are associated
with emissions from combustion of fuels by farm equipment and from airborne particles (dust)
generated during tillage and harvesting. Soil and related dust particles become airborne as a
result of field tillage, especially in drier areas of the country. In addition, emissions result from
the production and transport of fertilizers and pesticides used in corn and soybean production,
and the application of fertilizers and pesticides to each crop. Air emissions associated with
cultivation and harvesting of corn and soybeans for biofuel will mostly occur in sparsely
populated areas (Hill et al., 2009). Subsequent stages in the biofuel supply chain (see Figure
2-2), including feedstock logistics and biofuel production, distribution, and use, also affect air
quality and are discussed in Chapter 4.
Cultivating and harvesting corn and soybeans requires a range of mechanized equipment
that use different fuels, including diesel, gasoline, natural gas, and electric power (U.S. EPA,
2010a). Generally, equipment used to produce corn and soybeans consumes more diesel than for
most other crops, while the rate of gasoline consumption is somewhat less than that of other
crops. Primary emissions from fuel use include nitrogen oxides (NOX), volatile organic
compounds (VOCs), carbon monoxide (CO), sulfur dioxide (862), and coarse and fine
particulate matter (PMio and PM^.s). Gasoline use may also result in benzene, formaldehyde, and
acetaldehyde emissions. With respect to corn stover, additional fuel use depends on the method
of stover harvest. For example, methods that can simultaneously collect grain and stover will use
less fuel than those requiring multiple passes with a harvester. For this reason, one-pass
harvesters are currently being developed and tested (Shinners et al., 2009).
Cultivation also affects the release of CO2, NOX, and methane (CFL;) from the soil.
Conservation tillage practices, including no-till, are generally assumed to sequester greater
> oo
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Chapter 3: Environmental Impacts of Specific Feedstocks
amounts of soil organic carbon than conventional tillage, reducing CC>2 emissions—though
recent studies have questioned this finding (see Section 3.2.6.2). Additionally, there are
uncertainties regarding tillage and the release of NOX and CH4 from the soil. Time from the
initiation of tillage practices appears to be a determining factor (Six et al., 2004). In a meta-
analysis study, the implementation of no-till resulted in an initial increase in both N2O and CH4
relative to conventional tillage; within 20 years, however, cumulative emissions were
substantially lower under no-till, although N2O estimates were highly variable (Six et al., 2004).
Emissions are also associated with generation of electricity used for irrigation water
pumping. Irrigation power needs are estimated to range from 3 to 11 kilowatt-hours (kWh) per
irrigated acre, depending on the region, with a national average of 8 kWh per irrigated acre. For
soybean cultivation, electricity use is estimated to be 4.6 kWh per acre (Sheehan et al., 1998a;
Pradhan et al., 2008; Hill et al., 2006). Emissions associated with this use depend on the source
of the electricity consumed. Coal is the predominant fuel source for electricity in the Midwest,
accounting for 71.3 percent of generation in the 12 primary corn-producing states. Coal-fired
power plants are significant sources of 862, NOX, CO2, and mercury emissions.
Corn, with a moisture content over 18 to 20 percent, may require some drying to reach a
water content appropriate for storage (South Dakota State University, 2009). Grain driers use
liquefied petroleum gas (LPG) and electricity. LPG and electricity use depend on grain moisture
content at harvest. For example, typical Midwest grain harvest conditions and yields require 20
gallons of LPG per acre harvested. The exact amount depends on grain moisture conditions at
harvest.
Pesticides are commonly used on both corn and soybeans, with corn having more
intensive application rates (NRC, 2008, as cited in U.S. EPA, 2010a, Table 3-3) than soybeans.
Corn has the highest nitrogen fertilizer use per acre of any biofuel feedstock. Because soybeans
are legumes, they require much lower amounts of fertilizer, particularly nitrogen (NASS, 2006,
2007). Soybeans can acquire nitrogen from the atmosphere and therefore require less external
nitrogen fertilization than corn.
'Xj
Air emissions associated with fertilizer manufacturing and transport include NOx, SOX
VOC, CO, and particulate matter (PMio and PM2.s), while pesticide production and blending may
result in emissions of 1,3-butadiene, benzene, and formaldehyde (U.S. EPA, 2010a).
Application of fertilizers and pesticides may result in releases to the air. The primary
pollutants associated with the releases to air are benzene and acrolein. The results described in
U.S. EPA 2010a are consistent with another study, which found increases in benzene,
formaldehyde, acetaldehyde, and butadiene emissions, although that study included feedstock
transport and thus is not directly comparable (Winebrake et al., 2001). The application of
inorganic and organic fertilizers can increase NOX, ammonia (NHa), and CFLi emissions from the
soil (Mosier et al., 1996; Jarecki et al., 2008; Janzen et al., 2003; Das et al., 2008). Emissions of
CO, NOX, and SO2 increased with the use of corn stover as a feedstock in a hypothetical system
(i.e., a simulation based on corn stover life cycle data), with higher NOX emissions mainly due to
denitrification of increased amounts of nitrogen fertilizers added to farm soils (Sheehan et al.,
2004).
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.2.8. Ecosystem Impacts
3.2.8.1. Terrestrial Biodiversity
Overall, row crops provide habitat for a less diverse set of species than pasture or CRP
lands (Fletcher et al., 2010). Using a meta-analysis approach, Fletcher et al. (2010) found that
bird abundances are significantly lower in row crops, particularly for species of conservation
concern. However, no-till fields have a greater diversity and abundance of species, including
birds, invertebrates, and small mammals (Warburton and Klimstra, 1984). A variety of
conservation management practices on cropland can improve wildlife habitat, including
providing nesting and winter cover (Brady, 2007). Yet additional conversion of pasture or CRP
lands will contribute to additional habitat loss and landscape homogenization (Landis et al.,
2008; Fletcher etal., 2010).
While land use/land cover conversion in general contributes to a loss of landscape
diversity and increases in fragmentation, there is little evidence to date of widespread land use
changes due to biofuel production. Species' responses to habitat fragmentation are complex
(Ewers and Didham, 2006), which makes it difficult to discern effects due to biofuel feedstock
production. Habitat isolation can alter dispersal success and population structure within
fragments; this has longer-term consequences for genetic, morphological, and behavioral traits of
species (Ewers and Didham, 2006). Breeding bird surveys in Iowa found that the abundance of
nesting species increases in diverse landscapes with mosaics of crop and non-crop habitats, as
compared with crop monocultures (Brady, 2007). If landscape diversity decreases (especially if
CRP land is converted to corn), migratory birds may lose habitat and will likely decline in
numbers. On CRP lands, several grassland bird species have increased in abundance, and it is
estimated that without the 7.4 million acres of CRP in the Prairie Pothole region of the United
States, over 25 million ducks would have been lost from the annual fall migratory flights
between 1992 and 2004 (Dale et al., 2010).
The removal of corn stover residues from agricultural corn fields for ethanol production
also has potential consequences for biodiversity by reducing habitat and food sources (Brady,
2007). Increased crop residue amounts on fields generally result in a greater diversity of small
mammals (Brady, 2007), while removing crop residues has been shown to negatively affect both
terrestrial and soil organisms (Lai, 2009; Johnson et al., 2006). Similar to no-till practices,
maintaining crop residues like corn stover on fields can increase the diversity of beneficial soil-
dwelling invertebrates that can improve soil quality (Brady, 2007).
Increased corn production can also impact other aspects of biological diversity and
associated ecosystem services. In Iowa, Michigan, Minnesota, and Wisconsin, biological control
of soybean aphids declined due to lower habitat diversity as the proportion of corn in the local
landscape increased, resulting in increased expenditures for and application of pesticides, and
reduced yields (Landis et al., 2008). This results from reduced landscape diversity that decreases
habitat availability for many insects and animals in the local region (Landis et al., 2008).
Similarly, intensification of soybean production and pesticide use may also threaten biodiversity
and nearby plants and animals (Artuzi and Contiero, 2006; Koh and Ghazoul, 2008; Pimentel,
2006). Also, agricultural herbicides affect the composition of local plant communities, which
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Chapter 3: Environmental Impacts of Specific Feedstocks
then affects the abundance of natural enemy arthropods and the food supply of local game birds
(Taylor et al., 2006).
3.2.8.2. Aquatic Biodiversity
The impact of increased corn and soybean cultivation on ecosystems and biodiversity
depends, in large part, on where crop production occurs and what management techniques are
used. Much of the Midwestern landscape uses some type of surface or subsurface drainage to
convey water away from fields. These drainage waters carry sediments, nutrients, and pesticides
into surface and ground waters (Blann et al., 2009). Approximately half of the nitrogen lost from
croplands travels through subsurface drainage and nearly two-thirds of it is subsequently released
to surface waters, where it is combined with the 21 percent of nitrogen directly lost to runoff
(NRCS, 2010a). In surface waters these inputs result in eutrophication and increased turbidity.
Eutrophication can occur as fertilizer application increases nutrient loadings (nitrogen and
phosphorus) in surface waters such as streams, rivers, lakes, wetlands, and estuaries (Carpenter
et al., 1998; Pollock et al., 2007; Breitburg et al., 2009; U.S. EPA, 2010a). Increased phosphorus
concentration has been correlated with declines in invertebrate community structure (Carpenter
et al., 1998), and high concentrations of ammonia nitrogen are known to be toxic to aquatic
animals (Kosmala et al., 1999; Faria et al., 2006). Severe oxygen depletion and pH increases,
both of which are correlated with eutrophi cation, can inhibit growth and lead to mortality in fish
and invertebrates (Carpenter et al., 1998; Pollock et al., 2007; U.S. EPA, 2010a). In addition, as
aquatic systems become more enriched by nutrients, algae growth can cause a shift in species
composition. Nutrient enrichment in estuaries leads to hypoxia, which limits biodiversity and
threatens commercial and recreational fisheries (Wang et al., 2007a; U.S. EPA, 2010a).
Cumulative effects of hydrologic and water quality changes due to agricultural drainage have led
to declines in intolerant, sensitive species; shifts in aquatic community composition; and
homogenization of aquatic faunal assemblages to more tolerant, generalist species (Blann et al.,
2009).
Crop production not only releases nutrients to water bodies, but also sediments.
Cultivation practices or corn stover harvest rates leading to soil erosion can increase wetland
sedimentation, which may, depending on sediment depths, cover viable seeds sufficiently to
prevent germination (Gleason et al., 2003). Row crops also release more sediment into wetlands
than perennial grasses (Nelson et al., 2006). An increased input of sediments into aquatic
ecosystems can increase turbidity and water temperatures and bury stream substrates, limiting
habitat for coldwater fish (U.S. EPA, 2006a).
In addition to nutrients and sediments, agricultural drainage and runoff can contain a
variety of pesticides and other pollutants that are transported into water bodies (Blann et al.,
2009). For example, Malcolm et al., (2009) project a four percent increase in continuous corn
production in response to biofuel demand, which is likely to lead to more herbicide application.
One such herbicide is atrazine, commonly used in the United States and predominantly on corn.
As part of the EPA's 2003 Memorandum of Agreement, atrazine registrants are required to
conduct watershed monitoring to ensure protection of aquatic ecosystems. If any of the
watersheds show levels of atrazine above the Agency's level of concern for two years, the
registrants must initiate watershed-based management activities in concert with state or local
watershed programs to reduce atrazine exposure (U.S. EPA, 2010g). To date the results show
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Chapter 3: Environmental Impacts of Specific Feedstocks
that for most locations monitored, atrazine levels are below EPA's current level of concern.
Although EPA concluded in 2007 that atrazine does not adversely affect amphibian gonadal
development based on a review of laboratory and field studies (FIFRA Scientific Advisory
Board, 2007), the Agency has begun a comprehensive reevaluation of atrazine's ecological
effects, including potential effects on amphibians, based on data generated since 2007.
Fungicide pollution from runoff events also has been shown to impact algae and aquatic
invertebrates in areas where soybeans are intensively grown (Ochoa-Acuna et al., 2009). Manure
application can also lead to runoff that contains pathogens such as Salmonella sp.,
Campylobacter sp., and Clostridiumperfringens, along with additives such as livestock
antibiotics and hormones (Unc and Goss, 2004; Lee et al., 2007b; Brooks et al., 2009).
Conservation practices that are implemented and encouraged for erosion control and to
reduce nutrient losses—such as grass or riparian buffers, constructed/restored wetlands, or
enrollment in CRP—can ameliorate some of the ecosystem impacts described above. Compared
with the 56.6 percent of nitrogen lost from conventionally farmed croplands, conservation
practices reduce overall nitrogen loss by 18 percent on average, although this depends on
location and specific practices (NRCS, 2010a). Lands used for these management strategies can
serve as habitat for a variety of species and have been shown to improve species diversity and
abundances in agricultural landscapes, especially if these lands are left uncultivated for long
periods (van Buskirk and Willi, 2004; Brady, 2007). Agriculturally dominated landscapes with a
diversity of natural or non-crop habitats can also enhance the abundance and diversity of
predators of insect pests (Bianchi et al., 2006). However, the value of such habitats varies by
species, habitat composition (e.g., habitat type, plant species richness), and landscape structure
(e.g., habitat heterogeneity, surrounding land uses, connectivity) (Jeanneret et al., 2003), and
specialist species are less likely to benefit from these types of habitats and heterogeneous
landscapes (Filippi-Coadccioni et al., 2010).
3.2.8.3. Invasive Plants
Though neither corn nor soybeans are native to the United States, modern varieties of
corn and soybeans under production today in the United States pose little risk of dispersing seeds
or regenerative plant parts or creating hybrids with related plants that will become weeds or
invasive plants in the future. Corn and soybeans rarely overwinter successfully in major
production areas, but on occasion, seed from the previous year's crop can emerge in the
following year and the plants persist through a single growing season as a weed. Such
populations of plants do not become a chronic problem, however, because they do not sustain
themselves (Owen, 2005). To date, no cases of invasive corn or soybeans have ever been
reported in natural areas in the United States.
The extensive cultivation of row crops that are genetically engineered to resist
glyphosate, a commonly used herbicide, may result in indirect effects on other weed species and
invasive plants. One study correlated the increased use of this herbicide with the appearance of
glyphosate resistance in at least 10 agricultural weeds in the United States; loss of effectiveness
of glyphosate could encourage the use of more toxic herbicides (NRC, 2010a).
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.2.9. Key Findings
Much of the environmental impact of corn starch ethanol and soybean biodiesel
production depends on the types of land put into cultivation. To date, most additional acreage has
originated from lands currently in crop production. Expanding corn crop production to CRP or
pasture will likely have the greatest environmental impacts. Between September 2009 and
August 2010, approximately 35 percent of corn consumed domestically was converted into
ethanol biofuel (ERS, 2010c, 2010d). Corn acreage has increased over 2005 levels in part due to
ethanol demand, and planted acreage is expected to increase from 2008/2009 levels of 86 million
acres to 90 million acres in 2019 to meet the EISA target of 15 billion gallons per year (USDA,
2010c). The most plausible scenario at this time is that these additional acres will be
conventionally managed, tilled corn in predominantly rain-fed areas, replacing conventionally
grown soybeans or other row crops.
Currently, biodiesel accounts for approximately 5.5 percent of the soybean consumption;
USDA expects this percentage to increase to 7.7 percent by 2012 and hold steady through 2019.
Greater diversion of soybeans to biodiesel production will not result in additional impacts due to
land use change. USDA also expects that soybean acreages will hold steady at 76 million acres
(USDA, 201 Ob), though this number may increase to meet the EISA target. Moreover, it may be
necessary to increase acreage, yield, or the proportion of the soybean harvest that is devoted to
biodiesel in order to meet EISA targets (FAPRI, 2010a). The most plausible scenario for
soybeans at this time is that an increased proportion of conservation-tilled soybeans will be
diverted for biodiesel production.
The use of corn stover for ethanol production may not increase acreage dedicated to corn.
The most plausible scenario at this time is a 40 percent removal rate from conventionally
managed, tilled corn grown in predominantly rainfed areas as a separate harvest.
Increasing production of corn for ethanol and soybeans for biodiesel will likely have
implications for water quality. Increased corn and soybean production could increase nutrient,
sediment, and pesticide loadings to water bodies, including the Gulf of Mexico, Great Lakes, and
Chesapeake Bay, although fewer negative impacts are expected with soy production. Private
drinking water wells could see increases in nitrate and public drinking water systems could see
increases in their costs to lower nitrate levels. However, some of the potential increased nutrient
loadings from corn grown for ethanol might be reduced if farmers expand their use of
conservation practices. Increased risk of pathogens entering surface waters from application of
animal manure fertilizers is also possible. Removal of corn stover could lead to loss of soil
surface cover, thereby increasing runoff of nutrients, phosphorus in particular, and sediments to
surface waters; harvesting corn stover may reduce soil nutrient availability, leading to increased
fertilizer applications.
The magnitude of water availability impacts from increased corn or soybean production
for biofuel will vary geographically. If corn replaces other crops in the Midwest (the most
plausible scenario), water availability will be minimally impacted. However, if corn cultivation
replaces perennial grasses such as those on CRP land, it may reduce ET, leading to increases in
water availability. Increased corn and soybean production in areas requiring irrigation, such as
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Chapter 3: Environmental Impacts of Specific Feedstocks
the Great Plains, will increase water usage, potentially decreasing water availability. Removal of
corn stover for ethanol will not affect water availability in most parts of the United States.
Negative soil quality impacts from biofuel feedstock production can arise from
converting acreage with perennial vegetation cover to conventional corn and/or soybeans likely
increasing soil erosion, sedimentation, and nutrient losses. In contrast, allocation of a higher
percentage of corn or soybeans for biofuels from land already in production is likely to have
much smaller impacts. High stover removal rates are of particular concern with regard to loss of
soil and organic matter, which in turn can decrease soil carbon sequestration and adversely
impact crop yields. Impacts can be reduced through conservation practices, particularly no-till,
yet even with this management practice risks to soil organic matter from high stover removal
remain.
An increase in the production of corn and soybean for biofuel will likely lead to increased
pollution from fossil fuels associated with cultivation and harvesting and from airborne particles
(dust) generated during tillage and harvesting. Air emissions also result from the production and
transport of fertilizers and pesticides used in corn and soybean cultivation, and the application of
fertilizers and pesticides for each crop. Increasing their use will likely increase the volume of
emissions.
Ecosystem health/biodiversity impacts include degradation of aquatic life due to
eutrophication and herbicide runoff, impaired aquatic habitat due to sedimentation from soil
erosion, and decreases in landscape diversity. Conversion of CRP lands, which are
predominantly grasslands, may lead to declines in grassland birds, ducks, and other wildlife that
use these lands as habitat. Corn and soybean typically are not invasive in the U.S. corn- and
soybean-growing regions.
For a more comprehensive, qualitative comparison of the environmental impacts of corn,
soybean, and corn stover, including a discussion of the most plausible impacts, see Chapter 6.
3.2.9.1. Key Uncertainties and Unknowns
Uncertainties and a scarcity of data exist in many key areas concerning environmental
impacts of biofuel feedstock production. In particular:
• The impacts of additional corn and soybean production are determined by two
highly uncertain factors: where the production occurs and the types of
management practices employed. In particular:
— Increased corn and soybean yields may partially offset the need for
increased acres in production to achieve EISA goals in 2022. However,
the extent to which yield increases will be sustained is currently unknown,
and thus the extent to which increased production of corn and soybeans
will occur on marginal lands, CRP, and/or via continuous corn production
on existing lands now in rotation with other crops is also uncertain.
— The extent to which conservation practices are currently implemented on
cropland nationally is relatively unknown, and the potential for future
improvements, including improvements in yield; management of nutrients,
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Chapter 3: Environmental Impacts of Specific Feedstocks
pesticides, drainage, and energy use; and erosion control systems, is also
uncertain.
The ability to track impacts will depend on the quality and consistency of
monitoring fertilizer and pesticide usage, such as data provided by USDA's
NASS. USD A tracking of fertilizer application rates ended in 2005.
The ability to evaluate current and future water shortages associated with ethanol
and biodiesel production is limited by the available data. Annual measurements of
the extent of irrigation and amounts of surface and ground water used are not
systematically collected nationwide, forcing researchers to use incomplete
information to calculate crude water use estimates. The availability of fresh water
for a particular use is determined by many factors, including rainfall, soil water
retention and ground water recharge, water demand for competing uses, water
appropriation policy, and water contamination; attribution of water shortages to a
specific use may be difficult to measure without improvements in data collection
(Alley et al., 2002; Reilly et al., 2008).
The uncertainties regarding the effect of corn and soybean production on soil
quality arise predominantly from uncertainties regarding the amount and type of
land converted to corn or soybeans as a result of biofuel demand. Secondarily,
uncertainties regarding the effect on soil quality are caused by lack of detailed
land management data. For example, more frequent and detailed data—including
geographical location—on tillage practices employed would substantially reduce
uncertainties surrounding the soil quality response of producing biofuels.
The key uncertainties with respect to air quality impacts of increased corn and
soybean production are similar to those for water quality with respect to fertilizer
and pesticide use and application. In addition, NOX and NHa emission rates from
fertilized soil are highly uncertain and variable—they rely on microbial
conversion of fertilizer to nitrate, which in turn is influenced by environmental
conditions. Similarly, estimates of NOX emissions from the soil due to tillage
practices are highly variable, and a source of additional uncertainty. It is also
uncertain how extensively cover crops and tillage practices (both of which can
reduce fugitive dust emissions) are employed. For corn stover, there are a range of
assumptions regarding cropping practices, harvest techniques, and farm inputs
that require more study.
Ecosystem health and biodiversity, including fish and wildlife, are heavily
impacted by uncertain environmental factors such as nutrient and sediment runoff.
Nutrient loadings from row crop production into surface waters depend on many
different factors, including changes due to weather, and are therefore widely
variable (Powers, 2007). Regardless, the ability to reduce chemical exposure of
biota can be beneficial to the ecosystem and local biodiversity. In addition to
resolving uncertainties about those factors, more studies are needed on landscape-
level associations between corn and soybean production and terrestrial and
aquatic biodiversity, as well as biodiversity-related services such as pollination
and natural pest control. While conservation practices can improve habitat and
water quality, there is considerable uncertainty with respect to where these
practices occur, exactly how effective they are, and which species benefit.
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.3. Perennial Grasses
3.3.1. Introduction
Perennial grasses are herbaceous plants that grow in successive years from the same root
system. Seed production for most perennial grasses is lower than for grain crops such as corn,
resulting in starch and sugar contents that are inadequate for commercial production of biofuel
ethanol. However, an active field examining physical, chemical, and biological processes for
conversion of cellulose into fermentable sugars has emerged over the past three decades, making
perennial grasses an attractive feedstock. Cultivation of perennial grasses as biofuel feedstocks
has many potential environmental advantages over traditional row crops such as corn and
soybeans. However, major technological challenges exist for the development of these more
advanced biofuel conversion technologies, and the realization of these benefits depends largely
on where and how these crops are eventually grown. Currently, no commercial-scale facilities
for converting perennial grasses to cellulosic ethanol are operating in the United States.
However, several switchgrass cellulosic ethanol production facilities are under development
(RFA, 2010).
The predominant perennial grasses for biofuels are likely to be monocultures of
switchgrass (Panicum virgatum) or Giant Miscanthus (Miscanthus x giganteus). Other grasses
have also been explored and will not be thoroughly reviewed here, including Arundo donax,
Phalaris arundinacua, Sorghum bicolor, diverse mixtures of native species (see the text box in
Section 3.3.9), as well as various "cane" hybrids.
The selection of switchgrass as a model biofuel feedstock in the United States resulted
from decades of research by the USDA and DOE, including the Oak Ridge National Lab
(ORNL), following the oil crisis of the 1970s. The initial screening program examined 37
potential feedstocks, across a range of soil and management regimes, eventually resulting in the
selection of switchgrass in 1991 as the most promising overall feedstock for future study. A
recent review of the program is provided by Wright and Turhollow (2010), and all ORNL and
subcontractor reports have been made publically available on the Biofuels Feedstock Information
Network website.19 Switchgrass was selected as the most promising model feedstock, partially
due to funding constraints and partially because it met certain environmental, management, and
economic criteria. In short, switchgrass was selected because of its perennial life history (as
opposed to annual) and low demands for inputs after the first year, because of its reduced
environmental damages and economic costs, and because its yields were generally high and more
consistent from year to year, even though other feedstocks had higher yields in some locations
for some years (Wright and Turhollow, 2010). Following this screening, switchgrass was
intensively studied for 10 years, as summarized by McLaughlin and Kszos (2005). Several more
recent updates exist in the literature (e.g., Wullschleger et al., 2010).
Giant Miscanthus has been studied across Europe extensively since the 1980s (also in
response to the oil crisis of the 1970s) under the auspices of several national and multinational
programs. A review of these programs is provided in Lewandowski (2000). Giant Miscanthus
19 http://bioenergy.ornl.gov.
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Chapter 3: Environmental Impacts of Specific Feedstocks
had not been considered as a feedstock in the United States until recently (Heaton et al., 2004a,
2008). It has similar economic and environmental advantages to switchgrass. However, it is
likely more productive: it may be one of the most productive land plants in temperate regions,
though it is more difficult to establish (Heaton et al., 2008; Lewandowski et al., 2000).
Switchgrass is a native grass of North America that was widespread across much of the
Great Plains before European arrival (Parrish and Fike, 2005). Switchgrass is well adapted to
disturbances such as fire and grazing (Knapp et al., 1986) and has historically been grown in the
United States as forage for grazing livestock (Parrish and Fike, 2005). Several researchers note
that many studies have been published on switchgrass as a forage crop, but practices for forage
versus biofuel production can be quite different (e.g., harvest frequency; Heaton et al., 2004b).
Two major subtypes of switchgrass have been identified in the wild, an upland and a lowland
type, that differ in some key characteristics such as water use (Parrish and Fike, 2005). Research
from DOE and USDA across 15 states indicates a yield for switchgrass production averaging
from 4 to 10 tons per acre (McLaughlin and Kszos, 2005), in agreement with more recent
compilations (Wullschleger et al., 2010). There is considerable variation across sites, ecotypes,
management, and other factors. Farm-scale studies have demonstrated that ethanol yield from
switchgrass ranges from approximately 240 to 370 gallons per acre, compared to an average of
330 gallons per acre for corn grain (Schmer et al., 2008; assumes 0.0456 gallons per pound for
conversion of cellulosic biomass and 0.048 gallons per pound for conversion of corn grain).
Giant Miscanthus is a grass native to Asia, a rare but naturally occurring hybrid from two
parental species (Miscanthus sinensis and Miscanthus sacchariflorus) that have long been used
as forage in Asia (Stewart et al., 2009). Giant Miscanthus is sterile and does not produce viable
seed (Hodkinson et al., 2002). Thus, all individuals currently studied are genetically identical to
the original specimen brought from Japan in the 1930s. This horticultural specimen was soon
propagated and transported to Europe, and then later to the United States. Research from Europe
indicates variable but high productivities for Giant Miscanthus across Europe (2 to 25 tons per
acre), with higher levels in warmer wetter regions such as 13 to 14 tons per acre in Italy
(Lewandowski et al., 2000). The first replicated field trials for bioenergy production from Giant
Miscanthus in the United States occurred in Illinois from 2002 to 2004, and included side-by-
side comparisons with switchgrass. Researchers reported yields of 13 tons per acre for Giant
Miscanthus and 4.5 tons per acre for switchgrass (Heaton et al., 2008). Since then, other studies
have also demonstrated high yields in the United States (Propheter et al., 2010).
Considerable genetic variation for both of these species (for the parental lines of Giant
Miscanthus) has yet to be explored as a way to optimize feedstock production and biofuel
refining (Keshwani and Cheng, 2009; Vogel and Masters, 1998; Sarath et al., 2008; Carroll et al.,
2009; Demura and Ye, 2010). But promising traits, including low lignin and ash content and late
or absent flowering periods, indicate ample potential for high crop yields and efficient
conversion to ethanol (Jakob et al., 2009). Though standard irrigation, fertilizer, and pesticide
use practices for large-scale production have yet to be developed, the potential for biofuel
production from these feedstocks is promising.
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.3.2. Overview of Environmental Impacts
Because current production of perennial grasses for biofuels is negligible, current impacts
from their production under the RFS2 are also considered negligible. This is likely to change as
research and markets develop. As production of biofuel from perennial grass becomes
technologically and economically viable, demand for perennial grass will increase. This will
result in conversion of qualifying land to perennial grasses, the location and extent of which will
depend on region-specific agricultural and economic conditions. Perennial grass production will
likely require traditional agricultural activities, including pesticide, fertilizer, water, and
fuel/energy usage. The intensity of these activities relative to the land management practices they
are replacing will determine the extent to which perennial grass production impacts water
quality, water availability, air quality, soil quality, and biodiversity. Interestingly, even though
conversion from traditional row crops to perennial grasses is not expected to be a widespread
land use change in response to the RFS2, much of the literature on the environmental effects
from cellulosic biofuel production focuses on this transition rather than more likely transitions
such as from lands under the CRP. EPA is relying on peer-reviewed literature for this first
triennial report; thus, the remaining sections include caveats where appropriate to highlight this
mismatch.
3.3.3. Current and Projected Cultivation
Perennial grass species, including switchgrass, have historically thrived in the Midwest
and are generally well suited to grow as a biofuel feedstock over much of the continental United
States (see Figure 3-7). Current production of switchgrass and Giant Miscanthus as biofuel
feedstocks in the United States is limited to research field trials in several geographic locations
(reviewed in Heaton et al., 2008; Wright and Turhollow, 2010; and Wullschleger et al., 2010).
However, the vast majority of the nearly 31 million acres of lands in the CRP, which satisfy the
eligibility requirement for EISA, are dominated by perennial grasses, often switchgrass (Adler et
al., 2009; FSA, 2010).
> O O
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Chapter 3: Environmental Impacts of Specific Feedstocks
Hybrid Poplars
Switch grass
Sorghum
Switch grass
Hybrid Poplars
Switchgrass
Willows
Hybrid Poplars
Miscanthus
Sorghum
Switchgrass
Hybrid Poplars
Miscanthus
Pine
Sorghum
Sweetgum
Switchgrass
Energy Cane
Eucalyptus
Pine
Source: Dale et al, 2010, updated from Wright, 1994.
Figure 3-7: Generalized Map of Potential Rain-Fed Feedstock Crops in the Conterminous
United States Based on Field Plots and Soil, Prevailing Temperature, and Rainfall Patterns
Large areas of the eastern United States could support high-yield production of
Switchgrass (Thomson et al., 2009; Wullschleger et al., 2010). Economic models have projected
future cultivation of Switchgrass for biomass on CRP as well as existing cropland (de la Torre
Ugarte et al., 2003; Walsh et al., 2003). However, the policy and economic assumptions used in
those studies are no longer current. More recent economic analysis of commercial-scale
Switchgrass production suggests that displacement of crops such as corn and soybean is, at
present, unlikely (Nelson et al., 2006; Vadas et al., 2008; Jiang and Swinton, 2009; James et al.,
2010). The vast majority of land enrolled in the CJAP uses Switchgrass or other native or
introduced grasses (FSA, 2010) and commercial-scale Switchgrass trials frequently take place on
CRP or other marginal agricultural land (e.g., Perrin et al., 2008; Wright and Turhollow, 2010).
There are no similar studies for Giant Miscanthus in the United States.
Projected cultivation of perennial grasses, in terms of location and management practices,
is highly uncertain. In the near term, it seems likely that perennial grasses for cellulosic ethanol
will be produced on lands not already under active cultivation of high-value row crops.
3.3.4. Water Quality
Perennial grasses, often grown as a conservation practice along the margins of
agricultural fields to reduce sediment and nutrient runoff into surface water and wetlands, are
expected to have fewer water quality impacts than conventional agricultural crops (Keshwani
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Chapter 3: Environmental Impacts of Specific Feedstocks
and Cheng, 2009; Blanco-Canqui et al., 2004; Blanco-Canqui, 2010). This will depend, however,
on the agricultural intensity of the perennial grass cropping system (e.g., the extent of fertilizer
and pesticide use) and the land use that is replaced. In general, both switchgrass and Giant
Miscanthus have demonstrated positive responses to fertilization and water supplements, more so
for switchgrass with nitrogen and for Giant Miscanthus with water (Heaton et al., 2004b). These
responses vary substantially (Heaton et al., 2004a; Lewandowski et al., 2000; Wullschleger et al.,
2010; Wang et al., 2010). However, inputs for managed perennial grass cropping systems will
likely be higher than for unmanaged lands. Table 3-3 shows inputs needed to grow perennial
grasses compared to agricultural intensity metrics associated with growing conventional crops.
Table 3-3: Example Comparison of Agricultural Intensity Metrics for Perennial Grass,
Short-Rotation Woody Crops and Conventional Crops
Metric"
Erosionb
(T ac"1 yr"1)
Fertilizer (N P K)
(Ib ac"1 yr"1)
Herbicide
(Ib ac"1 yr-1)
Insecticide
(Ib ac'1 yr1)
Fungicide
(Ib ac'1 yr"1)
Perennial
Grassd
0.1
45 54 | 54
0.22
0.02
0.0009
Short-Rotation
Woody Crops'1
0.9
54 | 13 13
0.35
0.01
0.0001
Cornc
9.7
120 54|71
2.73
0.34
0.0007
Soyc
18.2
18 40 | 62
1.63
0.14
0.0009
Wheat0
6.3
54 31 |40
0.16
0.02
0.0089
a All metric units converted to English units. T/ac'Vyr"1 converted from Mg/ha'Vyr"1; Ib/ac'Vyr"1 converted
from kg/ha"1/yr"1.
b Conditions for average erosion rates: for corn and soy, 4 percent slope clay loam soil; for wheat, 4 percent
other soil; for perennial grass, after establishment; for short-rotation woody crops, 5 percent slope.
0 Fertilizer levels for corn, soy, and wheat are the approximate national average (USDA, 1991). Herbicide,
insecticide, and fungicide levels for corn, wheat, and soy are mean annual projections (USDA, 1991).
d Herbicide, insecticide, and fungicide levels for perennial grass and short-rotation woody crops are from
ORNL (1991). Unpublished estimates from field experiments of the Biofuels Feedstock Development
Program, 1978-1991.
Source: Ranney and Mann, 1994.
3.3.4.1. Nutrient Loading
Nutrients—Surface Water Impacts
Several factors affect losses of nutrients to surface waters, including fertilizer application
rates, irrigation, nutrient uptake rates by the crop, and soil and landscape properties. Results from
over a decade of research from DOE recommend application rates for switchgrass grown for
biofuels ranging from 37 to 107 pounds per acre per year, varying by region (McLaughlin and
Kszos, 2005). These findings are generally upheld by a more recent comparison of 18
publications across 17 states (Wullschleger et al., 2010).
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A meta-analysis of Giant Miscanthus in Europe and its response to management suggests
that nitrogen addition at approximately 90 pounds per acre per year stimulates growth by
approximately 15 percent after the third year of cultivation (Miguez et al., 2008). It should be
noted that this magnitude is small compared to responses of other crops. Similar detailed studies
in the United States are generally lacking (but see Heaton et al., 2008, 2009). A recent study
reported that Giant Miscanthus can fix atmospheric nitrogen, which could explain the relatively
weak responses to nitrogen fertilizer and lead to a large benefit to its use as a feedstock (Davis et
al., 2010). These findings remain to be confirmed in other studies.
Relative to annual row crops such as corn, production of switchgrass and Giant
Miscanthus requires less fertilizer and reduces surface and subsurface nutrient losses (Mclsaac et
al., 2010). Both species are inherently efficient in their nitrogen use, because they store
carbohydrates and nutrients in their roots at the end of the growing season (Beaty et al., 1978;
Beale and Long, 1997; Parrish and Fike, 2005; Heaton et al., 2009). Therefore, the practice of
harvesting the above-ground biomass after translocation of nutrients to below-ground storage
structures reduces the need for fertilization in subsequent growing seasons. In the only field
study to date comparing corn, Giant Miscanthus, and switchgrass under comparable conditions at
the field scale, Mclsaac et al. (2010) found that soil nitrate levels under mature stands of
switchgrass and Giant Miscanthus were lower than under fertilized corn (184 pounds per acre)
by 97 and 93 percent respectively. Less is known when these crops are grown under identical
management conditions or for other fertilizer inputs. However, switchgrass is considered
efficient in its use of potassium and phosphorus (Parrish and Fike, 2005), while Giant
Miscanthus may require additional potassium inputs in some circumstances (Clifton-Brown et
al., 2007).
In total, because of lower nutrient inputs and high efficiencies for switchgrass and Giant
Miscanthus, and lower water requirements especially for switchgrass, conversion of row crops to
perennial grass production will likely reduce surface water impacts from nutrient loading. If
perennial grasses are grown for biomass on CRP acreage, however, nutrient loading to
waterways may increase.
Nutrients—Coastal Waters Impacts
As mentioned above, switchgrass and Giant Miscanthus cropping systems are expected to
require fewer fertilizer additions than traditional row crops, and have been shown to reduce
chemical oxygen demand in runoff when used as filter strips (Keshwani and Cheng, 2009). This
will reduce their impact on the hypoxic zones of U.S. coastal waters if they replace row crops.
3.3.4.2. Sediment
Switchgrass and other perennial grasses are frequently used as an erosion control
management practice to reduce sediment loads from row crops (Hill, 2007; McLaughlin and
Walsh, 1998; U.S. EPA, 2009a). Perennial grasses such as switchgrass have been shown to
reduce erosion by 99.2 percent when compared to an average of corn, wheat, and soybeans (see
Table 3-3). Similar results are expected for Giant Miscanthus, which has been shown to produce
more root biomass in field comparisons with switchgrass (Heaton et al., 2008). Therefore,
because of their perennial root structure and assuming conservation-oriented agricultural
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Chapter 3: Environmental Impacts of Specific Feedstocks
practices, switchgrass and Giant Miscanthus production is not expected to increase sediment
loads to surface waters except possibly during the planting stages.
3.3.4.3. Pesticides
Perennial grasses are generally less susceptible to pests than traditional row crops
(Oyediran et al., 2004; Keshwani and Cheng, 2009). Switchgrass plantings use approximately 90
percent less pesticide than row crops (Keshwani and Cheng, 2009). However, herbicides are used
initially to establish and maintain switchgrass and Giant Miscanthus plantings for harvest
(Lewandowski et al., 2000; Keshwani and Cheng, 2009). Information relevant to potential
pesticide use for Giant Miscanthus in the United States is generally lacking; however,
researchers in Europe have reported that pesticide requirements are lower than for row crops
(Lewandowski et al., 2000).
Switchgrass and Giant Miscanthus have been found to be susceptible to insects such as
the corn leaf aphid, sugarcane aphid (Bradshaw et al., 2010), and fall armyworm (Prasifka et al.,
2009), as well as to nematodes (Tesfamariam et al., 2009) and pathogens (Parrish and Fike,
2005; Garrett et al., 2004; Christian et al., 2001; Lewandowski et al., 2000). However, disease
levels are considered generally low for both species compared to row crops and especially corn
studies. The lack of commercial perennial grass production as biofuel feedstock therefore makes
it difficult to predict how much pesticide would be needed for this application and what the
environmental impacts would be. However, it is likely that chemical inputs (e.g., herbicides)
would be needed during the establishment phase (Parrish and Fike, 2005; Lewandowski et al.,
2000). Research has found that herbicides that are safe for corn application can be safely applied
to Giant Miscanthus (Bullard et al., 2001). In non-commercial production, pesticide releases
from perennial grass plantings are much less than from corn or soybeans (Hill et al., 2006). Most
species are likely to be more susceptible to pests when grown in monocultures than in
polycultures (Hooper et al., 2005).
As an example, cellulosic feedstock production may impact the spread of the western
corn rootworm (WCR), whose soil-borne larval stage is estimated to be responsible for more
than $1 billion in annual losses in the U.S. Corn Belt (Rice, 2003). Recent research reported that
WCR is able to use Giant Miscanthus and several North American grasses as a host, though not
as effectively as corn (Oyediran et al., 2004; Spencer and Raghu, 2009). Similar information on
WCR use of switchgrass as a host is not available, though perennial grasses generally are more
resistant to pests than corn (Lewandowski et al., 2003; Oyediran et al., 2004).
3.3.4.4. Pathogens and Biological Contaminants
The reviewed literature does not directly discuss the effect of perennial grass plantings on
pathogens in runoff or the potential for pathogen loads associated with perennial grass
management (i.e., from manure used as fertilizer). Since perennial grasses require fewer inputs
and take up more impurities from surface water, fewer contaminants are expected from its
growth compared to row crops.
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3.3.5. Water Quantity
3.3.5.1. Water Use
Switchgrass and Giant Miscanthus are both C4 grasses (like corn) that use water
efficiently and are adapted to warmer environments. Neither appears to require water inputs to
attain high yields, except in arid regions, when summers are dry, and in very dry years (Beale et
al., 1999; Lewandowski et al., 2000; Heaton et al., 2004a; McLaughlin and Kszos, 2005; Wang
et al., 2010). However, both species have been found to increase yields with higher water inputs,
more so for Giant Miscanthus than switchgrass (Heaton et al., 2004a). Thus, it is unclear whether
switchgrass or Giant Miscanthus, when grown as bioenergy crops, will be irrigated or not and to
what degree, though it is assumed that both will require fewer water inputs than row crops.
Generally, studies that calculate water use for ethanol produced from switchgrass often assume
that the feedstock is rain-fed, requiring no irrigation, and is capable of tolerating moisture
deficits (e.g., Dominguez-Faus et al., 2009; Wu et al., 2009). In the first comparative study to
date of corn (Zea mays), switchgrass, and Giant Miscanthus, Hickman et al. (2010) found that
the cumulative ET and water use over the growing season was higher for Giant Miscanthus than
corn, with switchgrass as intermediate. This was mostly because the perennial grasses had a
higher leaf area and a longer growing season (Dohleman et al., 2009; Hickman et al., 2010).
High biomass production for Giant Miscanthus did not offset this water usage in terms of
efficiency. Thus, the common presumption that perennial grasses will use less water depends on
the details of how and where they are grown, and what land use they replace.
The upland and lowland types of switchgrass differ in their water use. The upland type
tends to tolerate dry conditions, while the lowland type requires more water (Parrish and Fike,
2005). Switchgrass farmers may be able to minimize potential irrigation withdrawals (and ET)
by cultivating the upland type of switchgrass. Given the clonal origins of most Giant Miscanthus
studied to date, it is likely that the range of sensitivities to water stress will be low, though the
same may not be said of its parent species (M. sinensis andM sacchariflorus\ which are known
to have high genetic variability (Hodkinson et al., 2002).
3.3.5.2. Water Availability
Depending on where perennial grasses are grown, whether irrigation is required, and
what crops they replace (if any), perennial grass production could improve or worsen water
availability. If perennial grasses replace more water-dependent crops, ground water availability
could be improved in places like Nebraska, where aquifers provide 85 percent of the water to
agriculture (Kenny et al., 2009; NASS, 2009a). On the other hand, if ground water-irrigated
perennial grasses replace unmanaged CRP land, water availability would be expected to be
reduced.
Changes in ET as a result of the cultivation of perennial grasses could either increase or
decrease field-level or local water supplies. Higher cumulative ET for Giant Miscanthus and
switchgrass compared to corn (Hickman et al., 2010) suggests that growing perennial grasses
may decrease surface runoff and subsurface infiltration, and increase ET (VanLoocke et al.,
2010). This has been a growing concern in Europe (Richter et al., 2008) and the United States
(VanLoocke et al., 2010). These impacts, along with albedo effects from a longer growing
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Chapter 3: Environmental Impacts of Specific Feedstocks
season, may lead to increases in local and regional humidity and to a local cooling (Georgescu et
al., 2009). A modeling study for an Iowa watershed reported that converting corn-soybean to
perennial grasses (i.e., switchgrass) would increase ET and reduce water yields measured
through annual stream flow by about 25 percent (Schilling et al., 2008). A recent regional
analysis of the impacts of widespread cultivation of Giant Miscanthus in the Midwest found
increases in ET and decreases in surface runoff by 1.6 inches per year or more when Giant
Miscanthus is planted over 25 percent or more of the region (VanLoocke et al., 2010). Dramatic
changes were predicted when cover exceeded 50 percent. However, no significant changes were
found when Giant Miscanthus covered 10 percent of the land area (though coverages between 10
percent and 25 percent were not examined). These simulations may not reflect likely scenarios.
In addition, given the high productivity for these grasses, such high levels of cultivation may be
unlikely to be needed to meet RFS2 standards (VanLoocke et al., 2010). In either case, these
changes could have large impacts on ecosystem services tied to the hydrologic cycle (Brown et
al., 2005). Much more work is needed to determine recommended practices for growing
perennial grasses as a bioenergy feedstock to determine subsequent impacts on water quantity.
3.3.6. Soil Quality
3.3.6.1. Soil Erosion
Both switchgrass and Giant Miscanthus have extensive root systems that prevent the
erosion of soil. In addition, unlike corn and soybeans, these perennial grasses are not planted on
an annual basis, reducing the frequency of soil disturbance. Currently, switchgrass can be planted
in conventional tillage and no-till systems, whereas Giant Miscanthus is planted in tilled fields
(Heaton et al., 2008; Parrish and Fike, 2005). This one-time tillage can increase erosion risk,
particularly in Giant Miscanthus, where plant growth is slow the first year following planting and
does not provide substantial ground cover (Lewandowski et al., 2000). In subsequent years,
however, Giant Miscanthus stands generally have high yields and dense root mats (Heaton et al.,
2008; Lewandowski et al., 2000), and likely provide substantial erosion control benefits relative
to annually planted crops. Erosion control by switchgrass has received more study than that of
Giant Miscanthus. Switchgrass has been extensively planted on CRP acreage for erosion
reduction, and planting switchgrass in riparian zone grass barriers and vegetation strips has been
shown to substantially reduce runoff, sedimentation, and nutrient loss (Eghball et al., 2000;
Blanco-Canqui et al., 2004; FSA, 2009). Switchgrass intensively managed for biofuel feedstock
production, however, may increase nutrient losses relative to switchgrass plantings intended as
erosion control.
3.3.6.2. Soil Organic Matter
In general, soil organic matter increases more under perennial than annual species
because of the continuous accumulation of plant material (Sartori et al., 2006). Soil carbon is a
primary constituent of soil organic matter. If perennial grasses replace annual crops, perennials
will likely increase soil organic matter (Bransby et al., 1998; Schneckenberger and Kuzyakov,
2007; Blanco-Canqui, 2010). McLauchlan (2006) reviewed changes in soil organic matter
following agricultural abandonment, and concluded that soil organic carbon accumulated with
the cessation of agriculture and the establishment of perennial vegetation—although the
perennial vegetation was not subjected to periodic harvesting. Where perennials are planted on
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Chapter 3: Environmental Impacts of Specific Feedstocks
degraded soils with low organic matter content, soil erosion can be reduced and carbon stocks
restored (Clifton-Brown et al., 2007; McLaughlin and Kszos, 2005). For example, using stable
isotope data, switchgrass was predicted to increase soil carbon by approximately 12 percent on a
degraded soil over a decade of production and harvesting (Garten and Wullschleger, 2000).
Switchgrass planted on CRP acreage or former cropland eligible for CRP enrollment has
been shown to increase soil organic matter. When grown on former cropland eligible for CRP
enrollment, switchgrass, with annual harvesting, significantly increased soil organic carbon (in
the top 11.8 inches of soil) by an average annual value of 981 pounds per acre over a five-year
period (Liebig et al., 2008). In this particular study, the 10 switchgrass sites ranged along a
north-south transect from southern Nebraska to northern North Dakota, and the fields received
an average of 172 pounds of nitrogen per hectare per year. In another study conducted on CRP
acreage, switchgrass production increased soil organic matter, but only with the application of
fertilizers (Lee et al., 2007a).
Besides the influence of nitrogen fertilizer, the magnitude of soil organic matter
accumulation under these perennials can depend, in part, on harvest frequency, soil type, and site
preparation (Bianco-Canqui, 2010). Harvesting biomass reduces the amount of plant matter
available for soil organic matter; however, switchgrass production for bioenergy generally results
in the accumulation of soil organic matter (Anderson-Teixeira et al., 2009). Relative to reported
values for corn, soil carbon increased under Giant Miscanthus cultivation when its above-ground
vegetation was harvested annually; however, this result varied according to soil type, with
carbon increasing in a loamy soil but not in a sandier textured soil (Schneckenberger and
Kuzyakov, 2007). Finally, the effect on soil organic matter of preparing land for these biofuel
feedstocks has received little attention to date (Anderson-Teixeira et al., 2009). Soil preparation
for perennial grass cultivation will be much less frequent than for row crops (e.g., every decade
vs. annually) (McLaughlin and Kszos, 2005). Consequently, the effects on soil organic matter
will be smaller. Nevertheless, the amount of soil carbon lost from this conversion and the time
needed for perennials to regain that carbon requires further study.
3.3.7. Air Quality
As mentioned earlier, little is known overall about the extent to which fertilizer,
herbicides, and pesticides will be used to increase perennial grass production. The production of
fertilizer requires fossil fuel inputs, resulting in air pollutant emissions, including SOX and NOX
(U.S. EPA, 2010a). Studies indicate thatNOx emissions should decrease when perennial grasses
replace row crops as a biofuel feedstock (Wu and Wang, 2006). However, if they are instead
grown on marginal or CRP land that does not receive nitrogen inputs, total NOX emissions will
increase. Nitrogen fertilizer rates are based on field trials, which are not extensive (Wu and
Wang, 2006) and may differ from on-farm conditions (Hill et al., 2009). Much less is known
about phosphorus (P2Os) fertilizer requirements for either species, though the prevailing
assumption is that switchgrass and Giant Miscanthus will likely use as much phosphorus as row
crops, or less (Ranney and Mann, 1994; Lewandowski et al., 2000; Parrish and Fike, 2005).
These reductions would translate to lower SC>2 emissions if perennial grasses replace row crops,
and overall increased SO2 emissions if perennial grasses replace lands not receiving chemical
inputs (Wu and Wang, 2006). As described earlier in Section 3.3.4.3, perennial grasses are
expected to require less pesticide and herbicide than row crops, except when initially establishing
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Chapter 3: Environmental Impacts of Specific Feedstocks
perennial grass plantings when inputs can be comparable (Lewandowski et al., 2000; Parrish and
Fike, 2005). The lack of experience with commercial perennial grass production as a biofuel
feedstock precludes firm conclusions about potential air quality impacts.
As with corn and soybeans, harvesting of perennial grasses will involve use of farm
equipment, and thus is expected to generate NOX and PM emissions. However, VOC, CO, NOX,
PMio, PM2.s, and 862 emissions associated with switchgrass production have been reported as
being lower than emissions from corn or soybean production (Wu and Wang, 2006; Hess et al.,
2009b). Thus, similar to above, overall effects depend on whether perennial grasses replace row
crops or unmanaged (or relatively less managed) lands.
3.3.8. Ecosystem Impacts
3.3.8.1. Biodiversity
Research generally indicates that perennial grasses support a greater diversity of species,
including birds, small mammals, and invertebrates, than row crops (Herkert, 2007; Semere and
Slater, 2007a; Fargione et al., 2009; Dale et al., 2010). However, active management and
harvesting of perennial grasses for feedstock production is likely to negatively impact at least
some of these species (e.g., Murray and Best, 2003; Murray et al., 2003; Kaufman and Kaufman,
2008). Much of the scientific literature on biodiversity and biofuels compares row crops with
unmanaged lands or lands enrolled in the CRP, though highly managed perennial grass feedstock
cultivation systems are unlikely to resemble these unmanaged areas. Specific biodiversity
responses will depend on location, perennial grass species, and agricultural and conservation
management practices.
Many studies indicate that a greater diversity of birds and mammals is supported by
perennial grasses and CRP lands than by row crops such as corn or soybean (Herkert, 2007;
Fargione et al., 2009; Dale et al., 2010; Fletcher et al., 2010). Planting switchgrass in tallgrass
ecoregions can increase local grassland bird diversity (Roth et al., 2005). Switchgrass can also
serve as suitable breeding habitat for a variety of bird species and increase their abundance,
depending on the timing of harvest and other management practices (George et al., 1979; Murray
et al., 2003). CRP lands planted using native grass mixtures that include switchgrass generally
have greater bird abundances, diversity, activity, and breeding success in the winter than non-
native grass monocultures and several migratory non-game species of management concern
(Thompson et al., 2009). However, if land currently enrolled in the CRP subsequently is
harvested for switchgrass, some bird species may decline (Murray and Best, 2003; Murray et al.,
2003).
Research from Nebraska and Iowa shows that populations of white-tailed deer are not
likely to decline following conversion of land from corn to native grassland (i.e., dominated by
switchgrass), but may experience a contraction of home ranges to areas near row crops,
increasing crop losses and the potential for disease transmission among wildlife (Walter et al.,
2009). Research has also shown a greater abundance and diversity of beneficial insects in
switchgrass than corn, although additional research is needed on whether these species provide
increased pollination or pest suppression services and whether switchgrass also provides habitat
for insect pests (Gardiner et al., 2010; Landis and Werling, 2010). Overall, little research exists
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Chapter 3: Environmental Impacts of Specific Feedstocks
on the habitat value of managed switchgrass fields for other terrestrial species, such as small
mammals, reptiles, and many invertebrates.
In terms of some specific harvest practices, increases in avian diversity are insensitive to
whether switchgrass is strip harvested or completely harvested (Murray and Best, 2003).
However, field studies have shown that different species prefer habitats under different
management regimes, suggesting that switchgrass cultivation under a mosaic of field ages and
management regimes will maximize total avian diversity over a large landscape (Murray and
Best, 2003; Roth et al., 2005). Other factors also affect habitat quality, such as stand density and
the use of rotating unharvested areas as refuges of wildlife habitat. Research from Iowa found
that dense switchgrass fields managed for biomass often supported generalist species, and did not
support species of management concern (Murray and Best, 2003).
Impacts on aquatic ecosystems have received even less attention thus far. Stream flow in
Iowa rivers has been augmented by agricultural drainage since the mid-20t century, when row
crops came to dominate this area (Schilling et al., 2008), and conversion back to perennial
vegetation could bring surface water availability to more historical levels (see Section 3.3.5.2).
Characteristics of surface water flow are important determinants of aquatic biological
community health (Poff and Zimmerman, 2010). More research is needed to determine how
large-scale perennial grass production and management practices may affect aquatic ecosystems
(Powlson et al., 2005).
Research on how Giant Miscanthus cultivation might affect biodiversity in the United
States is virtually nonexistent, and it is uncertain whether research from Europe would directly
translate to U.S. communities and ecosystems. Nonetheless, studies in the United Kingdom have
shown that Giant Miscanthus can provide improved habitat compared to row crops for many
forms of native wildlife—including ground flora, invertebrates, small mammals, and bird
species—due to the low intensity of the agricultural management system (Semere and Slater,
2007a, 2007b). Research from the United Kingdom shows that non-crop plants from a wide
range of families (Poaceae, Asteraceae, and Polygonaceae) coexist within young Giant
Miscanthus cropping systems due to a lack of herbicide applications. These plots support a
greater diversity of bird populations than annual row crops, but less than with short-rotation
woody crops (SRWCs) such as willow (Bellamy et al., 2009; Sage et al., 2010). These effects are
likely to be transient as fields mature and crop height and coverage become more homogeneous
and dense (Bellamy et al., 2009; Fargione et al., 2009). Similar patterns may be likely for the
United States.
3.3.8.2. Invasive Plants
The risk that switchgrass or Giant Miscanthus (or any other perennial grass feedstock)
will become an agricultural weed or invasive plant depends on their specific biology and their
interaction with the environments in which they are grown. Invasive plant traits include rapid
growth rate, ability to grow in dense stands, efficient resource use, tolerance to a wide range of
environmental conditions, tolerance to disturbance, resistance to pests and diseases, and rapid
and widespread abilities to disperse and establish (Barney and DiTomaso, 2008). Unfortunately,
the traits that make a species potentially invasive often overlap with those of favorable biofuel
feedstocks (Raghu et al., 2006; Barney and DiTomaso, 2008). Properties of the environment that
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Chapter 3: Environmental Impacts of Specific Feedstocks
facilitate invasion include a moderate climate, fertile areas, low levels of pests and/or disease,
and low biodiversity (Stohlgren et al., 1999; Fridley et al., 2007), properties exhibited by many
agricultural locations in the United States. Thus, the potential for invasion exists.
Weed risk assessments are formalized procedures for determining invasion risk. They are
designed to predict invasive and non-invasive species/varieties and distinguish between them
based on a set of questions about their history of invasiveness in other places, biological traits,
and suitability for the environment into which they will be introduced. The most widely accepted
approach, developed for Australia (Pheloung et al., 1999), has been recently adapted and tested
in Florida (Gordon et al., 2008), Hawaii (Daehler and Carino, 2000; Buddenhagen et al., 2009),
and several areas in Europe (Crosti et al., 2010; Krivanek, 2006), with good predictive results.
This weed risk assessment approach, modified for California, indicated that switchgrass
could become invasive if introduced to that state (Barney and DiTomaso, 2008). Similar
potential for switchgrass invasion was found for Hawaii (Buddenhagen et al., 2009). Conversely,
Parrish and Fike (2005) anecdotally reported no records of switchgrass escaping cultivation in
Australia, Europe, and the Pacific Northwest of the United States. While it may be possible for
improved switchgrass varieties to become weedy anywhere in the United States, unimproved
varieties of switchgrass are considered non-invasive in their native range. Switchgrass varieties
for biofuel production are being bred for rapid growth, tolerance to low fertility soils, and the
ability to grow in dense stands (Parrish and Fike, 2005; Rose et al., 2008; Sarath et al., 2008; Das
and Taliaferro, 2009; Yang et al., 2009), all of which could increase invasive potential. On the
other hand, breeding for traits like sterility can be used to reduce the risk of invasion. Reapplying
the aforementioned weed risk assessment in California, assuming switchgrass bred for seed
sterility, yielded a non-invasive result (Barney and DiTomaso, 2008).
Little experimental information exists about the ability of Giant Miscanthus to disperse
from cultivation and persist as a weed or invade natural areas, but testing in Europe since the
mid-1980s has not resulted in any known escapes (Lewandowski et al., 2000). A modified
version of the Australian weed risk assessment recommended no restrictions on planting current
varieties of Giant Miscanthus in the United States, because the plant produces no living seeds
and is therefore unlikely to spread (Barney and DiTomaso, 2008). Using the weed risk
assessment developed for Florida, Gordon et al. (2008) recommended no restrictions on Giant
Miscanthus.20 An earlier study noted that Giant Miscanthus can spread vegetatively and could
undergo genetic changes to produce seeds once more, potentially enhancing invasive potential
(Raghu et al., 2006). However, the likelihood of such an event remains unknown. Relatives of
Giant Miscanthus, especially Miscanthus sinensis, have been grown in the United States for
landscaping and horticultural purposes for decades (Stewart et al., 2009). Several researchers
have highlighted the potential invasiveness of M. sinensis (Raghu et al., 2006; Barney and
DiTomaso, 2008; Davis et al., 2010; Kaufman and Kaufman, 2008).
20 See http://plants.ifas.ufl.edu/assessment/ for a full explanation of the assessment and approved management
practices.
> A O
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Another way a feedstock could escape cultivation is by crossing with free-living
populations of compatible plants. Switchgrass, being native to the United States east of the
Rockies and highly outcrossing, could transfer traits from conventionally bred or genetically
modified cultivated varieties to wild populations. The effect on wild populations would depend
on the frequency of crossing, the traits transferred, and the environment, but could include
outcomes ranging from extinction of wild switchgrass populations to negligible or benign effects
to enhanced invasiveness of crop-wild hybrids (Ellstrand et al., 1999). Because there are no wild
populations of Giant Miscanthus in the United States and it is sterile, there is no possibility of
escape through outcrossing.
Some other grass species that have been considered for use as biofuel feedstocks
currently invade wetlands, including giant reed {Arundo donax) (Bell, 1997) and reed
canarygrass (Phalaris arundinaced) (Lavergne and Molofsky, 2004). Arundo donax has been
evaluated by several weed risk assessment protocols and has a high likelihood of becoming
invasive in Florida, where production is being proposed (Barney and DiTomaso, 2008).
While feedstock cultivation poses the greatest risk for invasive impacts, reproductive
parts from feedstocks could also be dispersed during transport from the field to storage or
ethanol-processing facilities. Roads, railroads, and waterways can act as man-made corridors for
non-native and invasive plants. Harvested switchgrass possesses living seed and Giant
Miscanthus can reproduce vegetatively from plant cuttings, both of which may be dispersed
during feedstock transport.
Several mitigation options for reducing the potentially negative environmental impacts
from perennial grass production have been suggested. A prominent approach is to apply a weed
risk assessment and reject planting species or varieties that are predicted to be invasive
(Pheloung et al., 1999). Such an approach, though recently adopted generally by the U.S.
Invasive Species Advisory Committee (National Invasive Species Council, 2009), is not formally
a part of current RFS2 regulations surrounding cultivation of biofuel feedstocks. USDA's
Biomass Crop Assistance Program (BCAP) does define as ineligible for some forms of crop
assistance payments "any crop that is invasive or noxious or has the potential to become invasive
or noxious" as determined by local, state, and federal entities (USDA, 2010e). Another option is
to avoid cultivation of feedstocks with a history of invasiveness, especially in places that are
climatically similar to where invasion has already occurred. Breeding feedstocks to limit their
dispersal into other fields or natural areas could reduce the probability of invasion. Another
strategy for managing potential invasiveness is cleaning harvesting machinery and vehicles used
to transport harvested feedstock, which would help to decrease unintended dispersal. Though
prevention is most desirable, early detection and rapid response mechanisms could also be put
into place to eradicate persistent populations of feedstock species as they arise, but before they
have the chance to spread widely (DiTomaso et al., 2010). Such early detection and rapid
response mechanisms might involve local monitoring networks and suggested mechanical and
chemical control strategies (timing and application rate of herbicides, for example) devised by
local agricultural extension scientists for specific feedstocks.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Native Grasslands as a Biofuel Feedstock
Recent research has suggested using mixtures of native perennials as a biofuel feedstock on marginal or
infertile lands (Tilman et al., 2006, 2009; Campbell et al., 2008; Weigelt et al, 2009). This practice is limited by
several technological and management hurdles, but it is associated with many environmental benefits not found to
the same degree in other feedstocks discussed in this report. Termed "low-input high-diversity" (LIHD) mixtures,
they are essentially composed of several plant species that perform different functions within the community (e.g.,
high root mass to prevent soil erosion, nitrogen fixation to reduce fertilizer inputs) potentially at different times (e.g.,
spring versus fall) or the same function in a different manner (e.g., root growth and soil carbon sequestration at
shallow versus deeper soil depths). LIHD mixtures, by definition, have more plant biodiversity than other
monoculture-based feedstocks. This higher plant biodiversity is often associated with a variety of benefits, including
higher stability of production, higher quality of habitat for wildlife, lower potential for invasion of the community,
reduced need for chemical inputs (fertilizers, pesticides) (Fargione et al., 2009; Hooper et al., 2005; Loreau et al.,
2002; Reiss et al., 2009). Also, monoculture crops are expected to require more active management (e.g., to prevent
losses from pests) than polycultures such as LIHD (Hill et al., 2006; Tilman et al., 2009; Weigelt et al., 2009). When
systems are viewed as a composite of many co-occurring processes (e.g., primary production, soil stabilization, and
decomposition), polycultures sustain higher levels of multiple processes, sometimes termed "ecosystem
multifunctionality" (Hector and Bagchi, 2007; Fornara and Tilman, 2009; Zavaleta et al., 2010). Diverse mixtures
also often produce more biomass than their average constituent species grown in monoculture; however, the
productivity of the most productive constituent species is in many cases similar to or higher than that of the mixture
(Cardinale et al., 2006, 2007; Loreau et al., 2002). Although it seems likely that highly productive feedstocks (e.g.,
switchgrass and Giant Miscanthus) managed for maximum yield will produce more biomass for biofuel production
than LIHD mixtures, there are no direct field-scale comparisons between LIHD and other feedstocks. The only
comparison to date found that switchgrass grown on fertile lands recently in production across the Midwestern corn
belt (Nebraska, South Dakota, North Dakota) out-produced LIHD grown on unproductive land in Minnesota that
had been abandoned from agriculture (Schmer et al., 2008). Production of a feedstock composed of a mixture of
species will likely face greater technological and management hurdles than production of single-species feedstocks.
For example, a mixture of species, having variable tissue densities and arrangements in the cropping system, may be
more difficult to harvest, transport, and process into biofuel than a relatively uniform feedstock grown from a single
species. Much more research is needed in this area to determine the potential role of LIHD as a biofuel feedstock on
marginal or infertile lands.
3.3.9. Key Findings
Current environmental impacts from the production of perennial grasses as a biofuel
feedstock are considered negligible because no large-scale commercial operations are yet in
existence. The potential benefits of using perennial grasses as a biofuel feedstock instead of
traditional row crops such as corn, however, are substantial. These can include reduced soil
erosion, enhanced soil structure and carbon sequestration, reduced nitrogen loading and
sedimentation to waterways, reduced hypoxia in coastal areas, and greater support for
populations of non-crop plants, as well as animals and soil biota (Fargione et al., 2009; Hill,
2007; Williams et al., 2009). These benefits occur because perennial grasses are likely to require
fewer chemical inputs than traditional row crops, and they have perennial roots that enable
longer planting intervals and less soil disturbance (Parrish and Fike, 2005; Keshwani and Cheng,
2009). However, the magnitude and even the presence of these advantages depends on whether
perennial grasses replace traditional row crops versus lands that are managed less intensively
(e.g., CRP acreage or pasture), as well as how grasses are managed. If perennial grasses replace
lands that received little or no inputs, and are grown with chemical amendments to increase
production in large-scale operations that resemble current row crops, overall environmental costs
may be significant. Studies highlighted above that incorporate agro-economic considerations
suggest that the most plausible land use change is conversion of unmanaged lands (e.g., CRP) to
perennial grass production, rather than conversion of row crops such as corn and soybean, due in
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Chapter 3: Environmental Impacts of Specific Feedstocks
part to the high market value of these row crops. The invasion potential for unimproved varieties
of switchgrass and Giant Miscanthus over most of the United States is considered low, though
little can be predicted about the invasion potential of improved varieties that may be developed.
In total, realizing the potential benefits of perennial grasses as a biofuel feedstock will
necessitate careful consideration of land use changes and management practices, as well as
widespread implementation of BMPs where possible.
For a more comprehensive, qualitative comparison of the environmental impacts of perennial
grasses, including a discussion of the most plausible impacts, see Chapter 6.
3.3.9.1. Key Uncertainties and Unknowns
• Because no commercial-scale facilities exist for converting perennial grasses to
cellulosic ethanol, many uncertainties remain about how perennial grasses will
affect environmental conditions when grown as feedstock at commercial scales.
This holds for all impact categories documented in this report (soil carbon,
leaching, biodiversity etc.), as well as for yields that may be lower in non-
experimental plots that are managed less intensively. This highlights the need for
large-scale studies comparing perennial grass cultivated under a variety of
management regimes with row crops and other feedstocks.
• Environmental impacts from cultivation of perennial grasses will probably be
largely driven by land use changes, which remain poorly understood, and
management practices.
• Most existing literature on switchgrass focuses on its ecology and uses as forage,
or focuses on dynamics in the context of CRP, which may or may not resemble
switchgrass grown for high yields as a biofuel feedstock. In short, this literature
might not be completely applicable.
• It is unclear how the abundant genetic potential for both switchgrass and Giant
Miscanthus (parental lines) can be used to increase their feasibility as feedstocks.
If researchers can develop novel cultivars of these plants with significantly
improved yields, there may be even greater benefits for perennial grasses as
biofuel feedstocks.
• Little is known about region-specific recommendations for fertilizer and pesticide
use for increasing perennial grass production. Precision management strategies
(e.g., minimal fertilization, irrigation, and pest management at specific times) may
increase productivity without deleterious ecological impacts.
• The water requirements of different grass species in different areas of the country
are not documented; however, widespread cultivation of perennial grasses may
negatively impact regional hydrologic cycles and related ecosystem services (e.g.,
aquifer recharge), while improving others (e.g., nutrient runoff).
• The role of nitrogen fixation in explaining the productivity of Giant Miscanthus
requires further study and may have large ramifications on the potential use of
Giant Miscanthus as a feedstock.
• The potential invasiveness of current varieties of switchgrass and Giant
Miscanthus over much of the United States is low, but the invasion risk of
improved varieties remains unknown. Studies to evaluate feedstocks for
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Chapter 3: Environmental Impacts of Specific Feedstocks
biological characteristics associated with invasiveness should be conducted, and
methods to synthesize this information (e.g., weed risk assessments) should be
applied to local situations for anticipating and preventing potential invasions.
• It remains uncertain whether the continual removal of above-ground biomass will
deplete soil nutrients over the long term, particularly on marginal soils. On these
soils, it may be particularly critical to harvest after translocation of nutrients back
into the root systems.
• More landscape-level research is needed to understand how the distribution of
multiple land use systems across a large landscape (e.g., row crops interspersed
with perennial biofuel grasses and native habitat) will affect local and regional
biodiversity.
3.4. Woody Biomass
3.4.1. Introduction
Woody biomass is an attractive energy source because extensive amounts may be
available domestically and, if managed correctly, the production of this feedstock can provide
environmental benefits. Woody biomass includes trees (e.g., removed or thinned from forests);
forest residues (e.g., limbs, tree tops, and other materials generally left on site after logging);
short rotation woody crops (SRWCs, i.e., fast-growing tree species, such as willow [Salix sp.]
and hybrid poplar [Populus sp.], cultivated in plantation-like settings); and milling residues.
Thinning is a common forestry practice that removes trees within a forest stand, stimulating
stand growth by reducing plant competition (e.g., Reukema, 1975). Rotation refers to the length
of time between tree establishment and harvesting. Currently, woody biomass is burned for
electricity generation in select locations in the United States, and pulp and saw mills use residues
to produce heat, steam, and electricity. In 2008, about 10 percent of the renewable electricity
generated in the United States came from woody biomass (White, 2010). Commercial-scale,
cellulosic-ethanol plants using this feedstock are not yet in operation, but demonstration and
development facilities exist.
Estimates of woody biomass available domestically differ widely and vary by price paid
per ton of feedstock. At $40 to $46 per dry ton, it has been estimated that approximately 4 billion
gallons of second-generation biofuel could be made from woody biomass (BRDI, 2008). EPA's
RFS2 RIA notes that at $70 per ton, 40 to 118 million dry tons are potentially available for
biofuel production in 2022 (U.S. EPA, 2010a). At a currently demonstrated conversion rate of 80
gallons of ethanol per dry ton, up to 9.4 billion gallons of ethanol could be produced from 118
million dry tons (Foust et al., 2009). Additionally, the conversion rate of biomass to ethanol or
other biofuels will likely improve in the future.
Not all woody biomass is eligible under the RFS2 requirements. The RFS2 limits the
origin of woody biomass to "planted trees and tree residue from actively managed tree
plantations on non-federal land cleared at any time prior to December 19, 2007" (U.S. EPA,
2010d).
Both forest harvesting residues and thinning operations are expected to be the
predominant sources of woody biomass for future biofuel use, but SRWCs might be important as
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Chapter 3: Environmental Impacts of Specific Feedstocks
well at higher feedstock prices (Perlack et al., 2005; U.S. EPA, 2010a; White, 2010). In the
following sections, the potential environmental impacts of the use of harvest residues, thinning,
and SRWCs are discussed in more detail. For comparison purposes, the environmental impacts
of SRWCs are considered in relation to annual row crops. Economic analyses, however,
conducted before the establishment of RFS2 guidelines, suggest that the most likely sources of
land for SRWC plantations are CRP or fallow agricultural lands, rather than prime agricultural
acres or grasslands (Volk et al., 2006; Walsh et al., 2003). Additionally, SRWCs replacing row
crops, grasslands, or unmanaged forests are ineligible as a biofuel feedstock according to the
RFS2.
3.4.2. Overview of Environmental Impacts
Current environmental impacts of production and use of woody biomass as a biofuel
feedstock are negligible, since no large-scale, commercial operations are yet in existence to
create demand for this feedstock. In the case of forest thinning and residue removal, there are
direct environmental effects of biomass removal, as well as an effect from operation of forestry
machinery. In the case of SRWCs, traditional forestry and agricultural activities undertaken
during feedstock cultivation and harvesting, such as pesticide or fertilizer application, irrigation,
and fuel/energy use, have the potential to impact the environment. If planted on degraded soil,
SRWCs can improve both soil and water quality. The choice of tree species can influence the
risk of establishment and impact of invasive species. All these activities can alter water quality
and availability, soil and air quality, and biodiversity, with resulting effects on ecosystems. The
extent of the impacts depends on each activity's intensity and the management practices in use.
3.4.3. Current and Projected Production Areas
Woody biomass is likely to be produced in major forest harvesting areas, predominantly
in places such as the upper Lake States, the Southeast, and the Pacific Northwest (see Figure
3-8). Since forest residues and biomass thinning will be collected as a byproduct of harvesting
operations, their usage is unlikely to produce land use/land cover changes (Williams et al., 2009).
To reduce the threat of catastrophic wildfires, thinning or other biomass removal may occur in
certain locations of high wildfire risk (USDA, 2005; Gorte, 2009). SRWCs will follow a similar
geographic pattern to that illustrated in Figure 3-7, since these are restricted to existing tree
plantations.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Biomass Resources of the United States
Forest Residues
Thousand
Dry Tonnes/Year
>100
50-100
25-50
10-25
5-10
<5
Not Estimated
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Figure 3-8: Estimated Forest Residues by County
3.4.4. Water Quality
3.4.4.1. Nutrients
Cultivation of woody biomass can affect water quality, primarily through nutrient runoff
and sedimentation. The effects of removing harvest residues on nutrient loads vary depending on
topography, soil nutrient content, and the chemistry of the residues themselves (Titus et al.,
1997). In a review analysis on logging impacts in boreal forests, Kreutzweiser et al. (2008) found
that harvesting with residue removal relative to harvesting-only generally increased soil nutrient
losses, but they failed to observe a clear trend in the export of nutrients to aquatic systems.
Residue removal has been suggested as a management technique to reduce nitrogen in forests
that receive high atmospheric deposition, such as in the northeastern United States (Fenn et al.,
1998; Lundborg, 1997). Under these circumstances, residue removal might decrease nitrogen
loads to waterways (Lundborg, 1997). Compared to forest residue removal, moderate forest
thinning typically does not affect loss of soil nutrients to ground or surface waters (Baeumler and
Zech, 1998; Knight et al., 1991). Baumler and Zech (1999) found that thinning increased stream
ion concentrations, particularly ammonium (NH4+), but the effects returned to pre-thinning
conditions within a year.
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Chapter 3: Environmental Impacts of Specific Feedstocks
As stated in the RFS2, SRWCs are only considered renewable biomass if cultivated on
non-federal, previously managed forest lands or existing forest plantations. For comparative
purposes, however, nutrient losses from SRWCs are, in general, considerably less than in
annually cropped systems (Table 3-3). In willow plantations, the recommended fertilizer
application rate is 89 pounds of nitrogen per acre (100 kilograms per hectare) every three years,
which equates on an annual basis to approximately 22 percent of the average rate for corn
production (Keoleian and Volk, 2005; NASS, 2006). Initially after planting, SRWC plantations
can exhibit losses of nitrogen at rates comparable to conventional corn production, yet following
this establishment phase, nitrogen losses decline to low levels (Aronsson et al., 2000; Goodlass
et al., 2007; Randall et al., 1997). A comparison of nutrient exports from a short-rotation poplar
stand and an undisturbed forest found no difference (Perry et al., 1998), and measurements of
nitrogen in ground water and leaching from established willow plantations generally show little
eutrophication potential for aquatic ecosystems (Keoleian and Volk, 2005). In coppiced systems,
where trees are harvested at the ground level and re-grow from the stump, the harvesting of the
above-ground portion of the tree appears to have little impact on nitrogen leaching (Goodlass et
al., 2007). Losses can be substantially higher when the stand is replanted (Goodlass et al., 2007).
Longer rotation lengths would likely improve nutrient retention on site and reduce losses to
waterways.
Pesticides might be used with SRWCs; for purposes of comparison, it is noted that the
amount used would be significantly less than that for corn or soybeans (Table 3-3; Ranney and
Mann, 1994).
3.4.4.2. Sediment
Forest soils generally exhibit low erosion rates and thus small sediment losses to surface
waterways (Neary et al., 2009). Forested riparian buffers reduce sediment and nutrient runoff
into adjacent streams compared to row crops or pasture land (Zaimes et al., 2004). Additionally,
erosion rates at harvested sites are relatively short-lived and decline once vegetation is re-
established (Aust et al., 1991; Miller et al., 1988). However, harvesting residues left on-site
physically shield soil particles from wind and water erosion, and promote soil stability through
the addition of organic matter. Thus, relative to harvesting-only operations, combined harvesting
and removal of residues could increase erosion and associated sediment loading to surface
waters, especially on steeper slopes (Edeso et al., 1999). Relative to undisturbed forests, thinning
can temporarily increase erosion on steeper slopes or in semi-arid areas with high risk of wind
erosion (Cram et al., 2007; Whicker et al., 2008).
3.4.4.3. Forestry Best Management Practices
According to the 2006 EPA National Assessment Database, forestry practices are a
relatively small source of water quality impairment to streams and other surface waters (though
the majority of states did not report this information) (U.S. EPA, 2006d). Louisiana, for example,
reported that about 3.5 percent of impaired stream miles were likely due to forestry practices,
compared to those attributed to such sources as agriculture (15.3 percent) and municipal
discharges (11.5 percent) (U.S. EPA, 2006d).
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Chapter 3: Environmental Impacts of Specific Feedstocks
BMPs have been demonstrated to be effective in reducing water quality impairment from
forestry activity, and may help ameliorate impacts from increased demand for woody biomass as
a result of biofuels (Shepard, 2006). Overall, there are generally high implementation rates for
forestry BMPs, although actual practices and rates of implementation vary by state (NCASI,
2009). BMPs include establishing stream-side management/buffer zones, minimizing the
construction of roads and stream crossings, using portable stream crossing structures, and
choosing low-impact equipment that is of the appropriate size and scope for the site (Phillips et
al., 2000; Aust and Blinn, 2004; Shepard, 2006). These BMPs have been shown to decrease
erosion and sedimentation to waterways. Improved logging road construction and maintenance
practices, for example, have been linked to decreases in sedimentation to streams in Oregon
watersheds (Reiter et al., 2009). In a Texas watershed study, McBroom et al. (2008) found that
modern harvesting techniques with proper use of BMPs significantly reduced erosion compared
to past logging activities.
3.4.5. Water Quantity
3.4.5.1. Water Use
The use of harvest residues from mature stands of trees and thinning does not require
additional water use at the feedstock production stage.
For the most part, growth of SRWCs will likely occur in areas with high water
availability, such as the Northeast, Southeast, and Northwest. Because they are usually not
irrigated, trees require less total water than row crops (Evans and Cohen, 2009). However, they
can still have a large impact on regional water availability due to their much higher ET rate. For
example, conversion of natural pine savanna and low-intensity pasture to plantations of slash
pine (Pinus elliotif) and loblolly pine (Pinus taedd) in the Southeast could result in nearly 1,000
gallons of additional water consumed per gallon of ethanol (Evans and Cohen, 2009). Further, in
certain locations and in some years, additional irrigation water may be required to maintain high
biomass accumulation (Hansen, 1988), though precision application systems can reduce the
amount of water applied. However, since SRWCs are only considered renewable biomass if
cultivated on previously managed forest lands or existing forest plantations, the risk of increased
ET rates is very low.
3.4.5.2. Water Availability
The use of forest harvest residues should have little or no effect on water availability at
the feedstock production stage. Forest thinning can increase streamflow, but data suggest that at
least 20 percent of the basal area of stand may need to be removed before a change in flow is
detectable (Troendle et al., 2010). Removal of woody biomass that has overgrown traditional
savannah grassland and dry forest ecosystems, largely due to fire exclusion, could provide a
benefit of increased streamflow for a period of time.
Plantations of SRWCs may reduce runoff into streams and rivers compared to traditional
row crops like corn and soybeans, potentially benefiting water quality (Updegraff et al., 2004).
However, some experts warn that reduced runoff coupled with high water requirements for
SWRCs could reduce or eliminate stream flow (Jackson et al., 2005). In places with seasonal
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flooding, modulation of surface water flow closer to pre-agricultural development levels could
possibly mitigate flooding risk (Perry et al., 2001). Like most feedstock production impacts, the
positive benefits or negative effects will depend on the location and practices used.
3.4.6. Soil Quality
3.4.6.1. Soil Erosion
The soil erosion impacts of SRWCs will depend on harvesting and planting frequencies;
impacts are lower when time between planting intervals is longer. Some species of SRWCs may
require intensive soil preparation for successful establishment, and it is during this brief
establishment phase that erosion rates can be high (Keoleian and Volk, 2005). For example,
higher sediment losses were observed within the first three years of seedling establishment in
sweetgum (Liquidamber styraciflua) plantations compared to no-till corn or switchgrass
(Nyakatawa et al., 2006). The slow-developing canopy failed to provide adequate ground cover
to protect against erosion as a result of rainfall (Nyakatawa et al., 2006). In established SRWC
plantations, soil erosion rates are much lower than those of annually harvested row crops
(Keoleian and Volk, 2005; Blanco-Canqui, 2010). The use of a cover crop can also significantly
reduce erosion caused by SRWC establishment (Nyakatawa et al., 2006), and the soil erosion
effects of SRWCs are likely to be lower under a coppicing system, which reduces the frequency
of soil disturbance by keeping the root systems intact. Willows are generally managed by the
coppicing system and harvested at three- to four-year intervals for a total of seven to 10 harvests
(Keoleian and Volk, 2005). This allows 21 to 40 years between soil disturbances.
3.4.6.2. Soil Organic Matter
Harvesting of forest residues removes plant material that could otherwise become soil
organic matter. A review study suggested that, on average, a complete, one-time removal of
forest residues slightly decreased soil organic matter in coniferous forests, but did not affect
levels in hardwood or mixed stands (Johnson and Curtis, 2001). A recent meta-analysis found no
significant impact on soil carbon with a one-time harvest and residue removal (Nave et al.,
2010). The importance of residues to soil organic matter can vary with forest type and soil.
Leaving logging residues can be particularly important for soils with low organic matter content,
and repeated harvesting of residues in the same location could lead to overall declines in soil
organic matter (Thiffault et al., 2006). The addition of commercial or organic fertilizers can
increase soil organic matter; therefore, this could be a management strategy to offset potential
losses due to residue removal (Johnson and Curtis, 2001). Thinning of forests has been shown to
reduce carbon in forest floor layers, but less evidence is available regarding its impact on soil
(Grady and Hart, 2006; Jandl et al., 2007). The effect of thinning over the long term will depend
on both the frequency and intensity of the specific thinning operations.
Production of SRWCs can add organic matter to the soil, sequestering carbon, but the net
benefits of these crops depend upon time between harvests and prior land use. If frequently
harvested short-rotation forests, particularly with residue removal, replace longer-rotation
forests, then the overall effect on soil organic matter over time is likely to be negative (Johnson
et al., 2010). Though a one-time harvest with residue removal might not by itself decrease soil
organic matter (see above; Johnson and Curtis, 2001), repeated removals of biomass at a greater
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frequency than longer-rotation forests are likely to decrease soil organic carbon over the long
term (Johnson et al., 2010). If SRWCs are planted on degraded, abandoned agricultural lands,
there is much greater potential to enhance soil organic matter (Schiffman and Johnson, 1989;
Huntington, 1995; Richter et al., 1999). Some initial soil carbon can be lost during forest
establishment in a former agricultural field (Paul et al., 2002). The amount of time it takes for
soil carbon to accumulate varies. In hybrid poplar plantations in Minnesota, it was estimated to
take 15 years to meet the carbon levels of the agricultural field replaced (Grigal and Berguson,
1998). A review study suggested that on average it can take 30 years to exceed soil carbon levels
of abandoned agricultural fields; though when the forest floor was also considered, carbon
accumulation rates were higher, reducing the time needed to regain carbon from the initial forest
establishment (Paul et al., 2002).
3.4.6.3. Soil Nutrients
Use of harvesting residues removes a potential source of soil nutrients that can be used by
the regenerating forest. Residue removal might reduce nitrogen loads in forests that receive high
atmospheric deposition (Fenn et al., 1998; Lundborg 1997), yet this risks depletion of calcium
and other nutrients critical for plant growth (Federer et al., 1989). Harvesting with residue
removal can lead to declines in soil nutrients and forest productivity, but in some cases, it can be
sustainable for at least one rotation (McLaughlin and Phillips, 2006; Thiffault et al., 2006).
Powers et al. (2005), in a survey of forest stands across North America, found that a one-time
harvest with residual removal did not affect stand productivity. In a subset of those sites, located
in North Carolina and Louisiana, Sanchez et al. (2006) observed a similar result, but did find
declines of soil phosphorus availability in the Louisiana stands. The cumulative effects of
repeated removals from the same site require further study. Application of commercial or organic
fertilizers may be necessary to compensate for nutrients lost. Overall, residue removal may be
less problematic on high-fertility soils than on coarser-textured, low-fertility soils (Page-
Dumroese et al., 2010). Since thinning operations remove less biomass than harvesting with
residue removal, the risk posed to soil nutrients by thinning is likely to be smaller (Luiro et al.,
2010).
There is concern that continual harvesting of SRWCs will deplete soil nutrients over the
long term (Adegbidi et al., 2001). Commercial fertilizers or organic waste products, such as
municipal effluent, can be used to offset these losses (Stanton et al., 2002). Nutrient removal
from such effluents by SRWCs could provide an additional environmental benefit, though it
remains unclear how much nitrogen, other nutrients, or contaminants might leach from these
systems if this technique is used.
3.4.7. Air Quality
Air quality impacts during harvesting of forest residues and thinning are associated with
emissions from combustion of fossil fuels by logging equipment. Few data are available for
evaluating air emissions from SRWCs such as hybrid poplar and willow. As with switchgrass,
SRWCs require less tillage (reducing fugitive dust emissions) and fewer applications of fertilizer
relative to row crops (reducing emissions associated with fertilizer production and application).
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However, some species such as poplar and willow that are potential feedstocks for
cellulosic ethanol are known to emit biogenic VOCs such as isoprene (U.S. EPA, 2010a),
although emissions of VOCs from these species are moderate compared to emissions from some
others (Isebrands et al., 1999). Compared to non-woody crops that emit relatively little isoprene,
these trees could affect ozone concentrations if planted extensively. This effect will be highly
sensitive to environmental conditions, preexisting vegetative cover, and the presence of other
atmospheric chemicals, especially NOX (Hess et al., 2009a; U.S. EPA, 2006b).
3.4.8. Ecosystem Impacts
3.4.8.1. Biodiversity
Both positive and negative consequences of residue removal on forest biodiversity have
been reported in the scientific literature. Forest residues or debris are habitat for many mammal,
bird, amphibian, reptile, and invertebrate species; function as plant germination sites; and are
positively related to the structure and composition of the understory plant community (Franklin
et al., 2002; Scheller and Mladenoff, 2002; Waddell, 2002; Janowiak and Webster, 2010).
Species diversity in forest ecosystems is strongly linked to structural diversity, of which forest
residues and woody debris are a component (Janowiak and Webster, 2010). The extent and
intensity of residue or debris harvesting and type of management employed will determine the
level of impact on biodiversity, both in terms of species diversity and abundances (Janowiak and
Webster, 2010). While understory cover and diversity often increase with increased levels of
forest thinning (Thomas et al., 1999), plant species diversity is generally highest in old-growth
forests and decreases under various forest management scenarios from selective cutting to clear
cutting (Scheller and Mladenoff, 2002; Khanina et al., 2007). Similar results have been
documented for amphibians (e.g., Karraker and Welsh, 2006) where abundance is greatest in
older forests, and not significantly different in thinned forests for some species. Some small
mammal species also increase in abundance under a variety of forest management practices (e.g.,
Homyack et al., 2005); and bird diversity and abundance are higher in thinned forests than more
intensively managed areas (e.g., Kalies et al., 2010). The results of these studies suggest that a
landscape with forest patches of different ages and careful management can support relatively
high species diversity and abundances, although questions remain about species-specific
responses, long-term conditions, and demographic consequences (Karraker and Welsh, 2006;
Niemela et al., 2007; Kalies et al., 2010).
Tree harvesting activities can impact aquatic biodiversity in a number of ways. For
example, removal of woody biomass by harvesting of forest residues or thinning in riparian areas
may reduce woody debris in headwater streams, an important component for aquatic habitat
(Angermeier and Karr, 1984; Chen and Wei, 2008; Stout et al., 1993; Thornton et al., 2000). In
addition, tree canopies over streams help maintain cooler water temperatures conducive to cold-
water smallmouth bass, trout, or salmon populations (Binkley and Brown, 1993; U.S. EPA,
2006c). Thinning practices in riparian areas that are consistent with widely applied forestry
BMPs are less likely to negatively impact aquatic communities, particularly when these practices
do not significantly reduce riparian canopy cover and increase stream temperatures (Chizinski et
al., 2010).
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The biodiversity effects of SRWCs versus other managed forests will likely depend upon
how much habitat complexity can develop during intervals between harvests. Several studies
have documented that bird species diversity on woody biomass plantations is comparable to that
of natural shrubland and forest habitats (Dhondt et al., 2007; Perttu, 1995; Volk et al., 2006),
although this is not always the case (Christian et al., 1998). Bird and small mammal species
found on SRWC plantations tend to be habitat generalists that can also use open habitats like
agricultural lands, while birds and small mammal species in mature forests are more specialized
and require forest cover (Christian et al., 1998). Changes in the type and amount of edge habitat
also can alter species interactions, since edges can serve as dispersal barriers or filters, influence
mortality, contribute to overall habitat use that maintains populations, and generate new
interactions (e.g., predation, competition); again, these processes are largely species-specific
(Fagan et al., 1999). Therefore, habitat edges can benefit some species and be detrimental for
others. If there is enough time between harvests to allow understory plants to establish in SRWC
plantations, bird species diversity can increase due to increases in habitat complexity (Christian
et al., 1998). Post-logging studies of birds also show species-specific responses, with some
species increasing in abundance immediately after logging and others increasing a decade after
harvest (Schlossberg and King, 2009). For comparison purposes, there is some evidence that
planting SRWCs can improve species habitat relative to agricultural crops (Christian et al.,
1998).
3.4.8.2. Invasive Plants
Like perennial grasses, woody plants cultivated for biofuel feedstock could become
invasive. This is based on documentation that trees used in forestry have become invasive,
though one estimate suggests most invasive trees were introduced for landscaping, not
production forestry (Reichard and Hamilton, 1997). Woody plant invasions can negatively affect
biodiversity and water availability (Richardson, 1998).
Predictive frameworks based on past invasions help identify what conditions and woody
plant traits make invasions more likely in the future. Different frameworks often consider
different factors. A study of determinants of woody plant invasion in Central Europe concluded
that long residence time (>180 years since introduction) and high planting intensity correlated
with escape and naturalization, while long residence time and ability to withstand low
temperatures correlated well with invasions (Pysek et al., 2009). If these factors hold true for the
United States, large-scale, widespread planting of woody biofuel species may pave the way for
invasion, though possibly not until the next century or beyond. In a study focused on North
America, woody plants that were native outside the continent or not sterile hybrids were more
likely to be invasive (Reichard and Hamilton, 1997). These results suggest that using species that
are native to the United States, or that are sterile hybrids between two species, could reduce the
risk of invasion. Finally, an assessment of risk factors in woody plant invasions of New England
identified plants that were invasive elsewhere and had a high growth rate as more likely to be
invasive (Herron et al., 2007), two factors that could be considered when promoting or
discouraging particular species as feedstocks.
In at least one case, a predictive assessment has been applied specifically to a woody
species discussed as a potential biofuel feedstock: Eucalyptus grandis in Florida (Rockwood et
al., 2008). The predictive assessment was based on the Australian Weed Risk Assessment
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(Pheloung et al., 1999) and modified for Florida growing conditions (Gordon et al., 2008). It has
been validated with 158 species introduced to Florida and has proven to possess good predictive
power. It correctly identified 92 percent of species independently determined to be invasive and
73 percent of species known to be non-invasive. E. grandis has been cultivated in Florida for
more than two decades and has not invaded. However, because this species could be planted
widely as a biofuel feedstock, when the predictive assessment was applied in 2009, E. grandis
received a conclusion of "Predict to be invasive; recommend only under specific management
practices that have been approved by the University of Florida's Institute of Food and
Agricultural Sciences Invasive Plant Working Group." Approved management practices for four
different cultivars include maintenance of a buffer around production areas and harvesting prior
to seed maturation.21
As with biofuels crops and grasses, it is possible that varieties of woody species, both
native and non-native to the United States, could be developed as biofuel feedstocks that have
significantly different traits than either varieties in production now or those woody species used
to develop predictive assessments. Some, like E. urograndis (E. grandis x E. urophylla)
genetically modified for freeze tolerance, may be grown in locations where they never have
before. Additionally, woody plants that have been selectively bred or genetically modified and
are also reproductively compatible with related species in the natural environment could transfer
those novel traits into wild populations. In all situations described, it would be important to
assess the likelihood of invasion or the transfer of novel traits to wild populations specifically
and carefully.
3.4.9. Key Findings
Current environmental impacts of production and use of woody biomass as a biofuel
feedstock are negligible, since no large-scale, commercial operations are yet in existence to
create demand for this feedstock. However, estimates suggest that the potential for biofuel
production from woody biomass is substantial, with predominant sources coming from forest
harvest residues, thinning, and SRWCs. The removal of forest harvest residues is the largest
source of woody biomass assumed in the RFS2 RIA (U.S. EPA 2010a). The most plausible
impacts from residue removal appear to be slightly negative for air and soil quality, especially
with multiple removals on nutrient-poor soils in the case of the latter. In some cases, the
application of fertilizers may be necessary to offset losses in soil nutrients. Other impacts appear
to be relatively negligible, particularly regarding water quantity and invasiveness. The
environmental impacts of moderate thinning regimes without residue removal appear to be
relatively modest.
Although woody biomass plantings eligible under RFS2 can be grown only on non-
federal, managed forested land, there are considerable benefits of planting SRWCs to replace
row crops or on degraded, abandoned agricultural land. For example, woody biomass species
require fewer inputs of fertilizer and pesticides than row crops, resulting in reduced runoff of
these substances into surface and ground water. In contrast, SRWCs grown to replace traditional
21 See http://plants.ifas.ufl.edu/assessment/ for a full explanation of the assessment and approved management
practices.
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managed forest land can exhibit a range of environmental impacts, depending on management.
SRWCs will have the most negative consequences if they significantly reduce forest replanting
intervals and require high water and chemical inputs. Additionally, the introduction of non-native
species or genetic modification that enhances invasiveness could increase the risk to native
populations. Conversely, if native species are planted and managed with limited soil disturbance
and low chemical and water inputs, SRWCs can provide environmental benefits relative to other
short-rotation managed forests.
For a more comprehensive, qualitative comparison of the environmental impacts of
woody biomass, including a discussion of the most plausible impacts, see Chapter 6.
3.4.9.1. Key Uncertainties and Unknowns
• Though there are commercial-scale power plants that generate electricity from
woody biomass, this biomass source is not yet converted to liquid biofuel on any
large scale. A mature cellulosic ethanol industry might demand more feedstock
than these current power plants, so its environmental impacts could be greater and
possibly differ. This uncertainty regarding future demand creates unknowns for
any projection of this feedstock's environmental effects, positive or negative.
• Specific environmental impacts will vary depending on forest and soil type,
topography, climate, and other factors.
• Lack of information about the amount and relative proportion of woody biomass
that would come from harvest residues, thinning, and SRWCs to support large-
scale operations creates substantial uncertainty. The potential effects of harvest
residues and thinning are easier to assess because a body of literature from other
forestry applications, such as whole-tree harvesting, does exist. Even so,
uncertainties arise from variations in the percent of residues removed during
harvesting and in the degree of thinning, which can range from small to large
proportions of the existing stand.
• Quantifying impacts of SRWCs to ecosystems and biodiversity will depend on
knowing where and under what agronomic conditions SRWCs are grown and how
they are managed. Uncertainty about these factors limits understanding of the
potential impacts of this feedstock.
3.5. Algae
3.5.1. Introduction
Algae are of interest as a biofuel feedstock because of their high oil content, ability to
recycle waste streams from other processes, and minimal land requirements (U.S. EPA, 2010a).
Algae production demands less land area per gallon of fuel produced than other feedstocks
(Dismukes et al., 2008; Smith et al., 2009).
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99
In the case of biofuels, the word "algae" typically refers to microalgae. There are many
different types of algae, methods to cultivate them, and processes to recover oil from them.
Algae grown photosynthetically are limited to growth during daylight hours and require carbon
dioxide. Heterotrophic algae, which do not use photosynthesis, can be grown continuously in the
dark, but require a fixed carbon source such as sugars because they cannot use carbon dioxide
directly (Day et al., 1991).
Basic research on algae as a biofuel feedstock was conducted by DOE under a program
known as the Aquatic Species Program (ASP) (Sheehan et al., 1998). The ASP focused on the
production of biodiesel from high-lipid-content algae grown in ponds, using waste CC>2 from
coal-fired power plants. Over the almost two decades of this program, advances were made in
the science of manipulating the metabolism of algae and the engineering of algae production
systems. However, very little research focused on the environmental consequences of large-scale
algae production. Research and pilot studies have shown that the lipids and carbohydrates in
microalgae can be refined and distilled into a variety of biodiesel- and alcohol-based fuels,
including diesel, ethanol, methanol, butanol, and gasoline (U.S. EPA, 2010a). Algae also have
the potential to serve as feedstock for other types of fuels, including bio-oil, bio-syngas, and bio-
hydrogen. This section focuses on the use of algae for biodiesel, because biodiesel is the most
likely near-term pathway for algae use as biofuel.
Cultivation of algae feedstocks can take place in photobioreactor facilities with closed-
cycle recirculation systems or in open-system-style impoundments. Open systems use pumps and
paddle wheels to circulate water, algae, and nutrients through shallow, uncovered containments
of various configurations. Closed systems employ flat plate and tubular photobioreactors and can
be located outdoors or indoors. Variations include hybrid (combined open and closed) cultivation
and heterotrophic cultivation (which uses organic carbon instead of light as an energy source).
Different algae cultivation strategies are being studied to determine which is most suitable for
supporting large-scale biofuel production (Chisti, 2007; U.S. EPA, 2010a).
Harvesting requires that the algae be removed, dewatered, and dried. Dewatering is
usually done mechanically using a screw press, while drying can use solar, drum, freeze, spray,
or rotary techniques (U.S. EPA, 2010a). After harvesting, the biofuel production process begins:
oil is extracted from the algae through chemical, mechanical, or electrical processes (U.S. EPA,
2010a). Algal oil can then be refined with the same transesterification process used for other
biofuel feedstocks such as soybean oil.
While the different methods of algae cultivation and recovery will clearly have very
different environmental impacts, such as energy consumption and chemical use and disposal, it is
premature to draw definitive conclusions about these impacts, given the nascent state of
cultivating algae for biofuel. Likewise, relatively few scientific studies have examined the
environmental impacts of algal biofuel production, although the literature was developing rapidly
as this report went to publication. The second triennial report to Congress will likely contain
22 The term "microalgae" refers to photo synthetic and heterotrophic organisms too small to be easily seen with the
naked eye—distinguished from macroalgae, otherwise known as seaweed. Macroalgae is generally not grown as an
energy crop. In this report the terms "algae" and "microalgae" are used interchangeably.
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much more information—from both industry and academia—on the environmental impacts of
algal biofuel production.
3.5.2. Overview of Environmental Impacts
Algae-based biofuel production systems are still being investigated at the pilot stage
using smaller-scale prototype research facilities. The potential environmental and resource
impacts of full-scale production are highly uncertain because much of the current relevant data is
proprietary or otherwise unavailable, and many key parameters are unknown, including where
and how algae will be produced and what species and strains of algae will be used as feedstocks.
Algae cultivation can require the use of pesticides, fertilizers, water, and fuel. Each of
these activities, in turn, can impact air quality, water quality, and water availability (soil quality
is likely not a concern). In addition to these impacts, there is potential for invasive algae strains
to escape from cultivation (Flynn et al., 2010). Industrial oil extraction and biodiesel production,
biodiesel and byproduct transport and storage, and biodiesel and byproduct end use also entail
environmental impacts, which are discussed further in Chapter 4.
3.5.3. Current and Projected Cultivation
Land use is one of the primary drivers behind interest in algae as a biofuel feedstock.
Relative to other feedstock resources, algal biomass has significantly higher productivity per
cultivated acre (Chisti, 2007). Moreover, algae cultivation requires relatively little land (e.g.,
about 2 percent compared to soybeans) (Smith et al., 2009). Algae's lack of dependence on
fertile soil and rainfall essentially eliminates competition among food, feed, and energy
production facilities for land resources (Muhs et al., 2009). Because algae-based biofuel
production facilities do not require specific land types, they may be sited closer to demand
centers, reducing the need to transport significant quantities of either biofuel or feedstock from
one region of the country (e.g., the Midwest) to another (e.g., coastal population centers).
Despite these potential advantages, significant long-term research and development will be
required to make microalgal biofuels processes economically competitive (Huesemann and
Brenemann, 2009).
Proximity to input sources (such as carbon dioxide sources) and output markets, as well
as the availability of affordable land, will likely drive algae production facility siting decisions.
The U.S. Southwest is viewed as a promising location for economical algae-to-biofuel
cultivation due to the availability of saline ground water, high exposure to solar radiation, and
low current land use development. Based on pilot studies and literature on algae cultivation,
likely areas for siting algae-based biofuels facilities also include coasts, marginal lands, and even
co-location with wastewater plants (Sheehan et al., 2004; U.S. EPA, 2010a). Algae grown in
conjunction with animal and human wastewater treatment facilities can reduce both freshwater
demands and fertilizer inputs, and may even generate revenue by reducing wastewater treatment
costs. U.S. companies are already using wastewater nutrients to feed algae in intensively
managed open systems for treatment of hazardous contaminants (Munoz and Guieysse, 2006).
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3.5.4. Water Quality
Scaled production of algae oil for biofuels has not yet been demonstrated; therefore,
water quality impacts associated with large-scale use of algae-based biofuels are currently
speculative. Wastewater is a key factor influencing water quality impacts of algae production
facilities, including whether wastewater is used as a water source for algae cultivation, and
whether wastewater is discharged from the algae cultivation site. Depending on the treatment
requirements, release of wastewater could introduce chemicals, nutrients, additives (e.g., from
flocculation), and algae, including non-native species, into receiving waters. Releases of
nutrient-rich growth media could affect water quality by inducing higher productivity of native
algae, which can contribute to eutrophication.
Co-locating algae production facilities with wastewater treatment plants, fossil fuel
power plants, or other industrial pollution sources can improve water quality and utilize waste
heat that contributes to thermal pollution, while reducing freshwater demands and fertilizer
inputs (Baliga and Powers, 2010; Clarens et al., 2010). When these facilities are co-located,
partially treated wastewater acts as the influent to the algae cultivation system. Algae remove
nutrients as they grow, which improves the quality of the wastewater and reduces nutrient inputs
to receiving waters. If fresh surface water or ground water is used as the influent, nutrients must
be added artificially in the form of fertilizer.
Significant environmental benefits could be associated with the ability of algae to thrive
in polluted wastewater. Algae can improve wastewater quality by removing not only nutrients,
but also metals and other contaminants, and by emitting oxygen. Thus, algae can effectively
provide some degree of "treatment" for the wastewater (Darnall et al., 1986; Hoffmann, 1998).
3.5.5. Water Quantity
3.5.5.1. Water Use
Water is a critical consideration in algae cultivation. Factors influencing water use
include the algae species cultivated, the geographic location of production facilities, the
production process employed, and the source water chemistry and characteristics. EPA has
estimated that an open-system biofuel facility generating 10 million gallons of biofuel each year
would use between 2,710 and 9,740 million gallons of water each year; a similar-scale
photobioreactor-type facility would use between 250 and 720 million gallons of water annually
(U.S. EPA, 2010a).
The harvesting and extraction processes also require water, but data on specific water
needs for these steps are limited (U.S. EPA, 2010a). Compared to the water required for algae
growth, however, demands are expected to be much lower.
3.5.5.2. Water Availability
The use of fresh water versus brackish, saline, or wastewater will largely determine the
effects of algae cultivation on water availability. If fresh water is employed, algae production
could exacerbate or create water availability problems, especially in promising locations like the
Southwest, which are already experiencing water shortages. However, the water used to grow
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algae does not have to be high-quality fresh water. Algae can thrive in brackish water, with salt
concentrations up to twice that of seawater, and can obtain nutrients from wastewater such as
industrial, agricultural, coal plant, and ethanol plant effluent (U.S. EPA, 2010a). Thus,
competition for freshwater resources may be mitigated by siting facilities in areas that can
provide suitable brackish or wastewater sources. Additionally, co-locating algae production
facilities with wastewater treatment plants can reduce, but not eliminate, water demands (Clarens
et al., 2010). Evaporation losses from open ponds could still reduce water availability if
wastewater could otherwise be treated and re-used. Relative to open ponds, the water availability
impacts of algae production can also be mitigated in large part by using photobioreactors, which
require less water and land area than open systems (U.S. EPA, 2010a).
3.5.6. Soil Quality
Very little peer-reviewed literature exists on the soil impacts of algae production. These
impacts are likely to be negligible and have therefore not been the subject of much study.
3.5.7. Air Quality
The effects of algae-based biofuels on air quality have received little attention to date in
peer-reviewed literature. As a result, additional research is needed to determine whether anything
unique to algae production processes would raise concern about air emissions.
Open or hybrid open systems appear to have greater potential to impact air quality
compared to enclosed photobioreactors, given the highly controlled nature of the latter systems.
No studies are yet available, however, to characterize or quantify emissions associated with open
systems used to produce algae for biofuel. Studies have measured air emissions of open-system
algae ponds that are part of wastewater treatment systems (Van der Steen et al., 2003), but these
studies may have very limited applicability to open systems for commercial-scale production of
algae oil for biodiesel. Additional research will be required to estimate and characterize
emissions from pumping, circulation, dewatering, and other equipment used to produce algae for
biofuel.
3.5.8. Ecosystem Impacts
3.5.8.1. Biodiversity
Algae production is likely to have fewer biodiversity impacts than production of other
feedstocks because algae typically require less land, fertilizer, and pesticide than do other
feedstocks, and because algae production plants may be co-located with wastewater treatment
plants. As mentioned above, the location of algae production facilities will be a key factor
affecting the potential for impacts. Using wastewater to capture nutrients for algae growth could
help reduce nutrient inputs to surface waters (Rittmann, 2008). Algae also require lower inputs of
fertilizers and pesticides than other feedstocks, which may translate into fewer ecological
impacts to aquatic ecosystems (Groom et al., 2008). Production facilities for algae that need
sunlight to grow could be located in arid regions with ample sunlight (Rittmann, 2008); however,
growing algae in areas with limited water resources could impact the amount of water available
for the ecosystem because of draws on ground water. It is unknown what impacts an accidental
algae release might have on native aquatic ecosystems, particularly if the algae released have
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been artificially selected or genetically engineered to be highly productive and possibly
adaptable to a range of conditions.
3.5.8.2. Invasive Algae
The potential for biofuel algae to be released into and survive and proliferate in the
environment is, at present, highly uncertain. It will depend on what species and strains of
naturally occurring, selectively bred, or genetically engineered algae are used and how they are
cultivated.
The risk of algae dispersal into the environment is much lower in closed bioreactor
systems than open system production, though unintentional spills from bioreactors in enclosed
production facilities are possible. High winds blowing across open systems may carry algae long
distances, depositing them in water bodies, including wetlands. Wildlife that enter the ponds may
also disperse algae to other water bodies. Closed systems, in addition to limiting algae dispersal,
have the benefit of protecting algal media from being contaminated with other microbes, which
could compete with the cultivation strains for nutrient resources.
Effluent from algal biomass dewatering processes may contain residual algae, which
could thrive in receiving waters. Treatment strategies will need to be developed to prevent algae
in effluent from contaminating the surrounding ecosystem.
The ability of cultivated algae to survive and reproduce in the natural environment is
unknown: one theoretical study suggests that native algae would out-compete some, but not all,
strains with the most desirable commercial characteristics (Flynn et al., 2010). Further empirical
work is critical to determine competitive and hybridizing abilities of biofuel algae in the natural
environment and to measure possible effects on algal community dynamics and ecosystem
services.
3.5.9. Key Findings
Current environmental impacts of production and use of algae as a biofuel feedstock are
negligible, since no large-scale, commercial operations are yet in existence. Due to the lack of
data on commercial-scale, the future environmental impacts of algae production are highly
uncertain. Nevertheless, some key findings can be ascertained from the established literature.
Unlike other feedstocks presented in this report, algae production does not require large amounts
of land. This means it could have a much smaller environmental footprint than other feedstocks;
its influence on water quality and quantity will largely determine its environmental impacts. This
influence, in turn, will depend on the type of water used and the production system. Algae
production using wastewater effluent, for example, can treat high levels of nutrients. Thus,
combining commercial-scale algae production with wastewater treatment plants may create
synergies that increase algae yields, while decreasing the environmental impacts of both
facilities. In contrast, using freshwater for production of algal biofuels will potentially decrease
water availability in areas such as the Southwest, where water is already scarce. Algae
production in open water ponds requires substantial amounts of water relative to the use of
photobioreactor systems.
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Though highly uncertain, the most plausible impacts of growing algae in open ponds
using wastewater are likely positive for water quality, slightly negative for water quantity, and
relatively negligible for other environmental end points. Open system cultivation systems may
have a greater potential than photobioreactor systems to adversely affect air quality, but no
studies have yet evaluated air pollutant emissions associated with these systems. Little is known
about how increases in algal biofuel production might affect biodiversity. Algae require lower
inputs of fertilizers and pesticides than other feedstocks, which may also translate into fewer
ecological impacts to aquatic ecosystems. The ability of cultivated algae to escape into and
survive in the natural environment is uncertain. Experts speculate that photobioreactor
cultivation systems would be superior to open systems in preventing the escape of cultivated
algae.
For a more comprehensive, qualitative comparison of the environmental impacts of algae,
including a discussion of the most plausible impacts, see Chapter 6.
3.5.9.1. Key Uncertainties and Unknowns
• Very little is known about the environmental impacts of commercial-scale algae
production.
• Most of the uncertainties related to the production of algae for biodiesel stem
from a lack of knowledge about which technologies may be used in future
commercial applications, where they will be located, and what species and strains
of algae will be used.
• Water availability impacts from feedstock growth will depend on where the algae
are grown, if open or closed systems are used, and whether water is recycled.
3.6. Waste-Based Feedstocks
3.6.1. Introduction
Diverse wastes, including construction debris, municipal solid waste (MSW), yard waste,
food waste, and animal waste, have the potential to serve as biofuel feedstocks. Depending on
the waste, conversion system, and product, potential exists for municipalities, industries, and
farmers to transform a material with high management costs to a resource that generates energy
and profits. Tapping into waste energy sources has many challenges, including dispersed
locations and potentially high transport costs, lack of long-term performance data, the cost of
converting waste to energy, and the possibility that the resulting biofuel might not meet quality
or regulatory specifications for use (Bracmort and Gorte, 2010).
Use of wastes as biofuel feedstocks will vary based on their availability, the ability of
conversion technologies to handle the material, and the comparative economics of their use for
fuel versus power and other products. Types and quantities of wastes used will vary by region. A
large number and variety of waste-based materials are being investigated and implemented as
feedstocks for ethanol and biodiesel, mostly on local scales. For example, several states—e.g.,
Massachusetts (Advanced Biofuels Task Force, 2008; Timmons et al., 2008), California (Chester
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Chapter 3: Environmental Impacts of Specific Feedstocks
9^
et al., 2007), and Ohio —have explored waste availability and its potential to meet regional
energy needs, either for power or for transportation fuel. Feedstocks may be converted to biofuel
or used as an energy source to power a biorefinery.
3.6.2. Municipal Solid Waste
The biogenic portion of MSW (paper, wood, yard trimmings, textiles, and other materials
that are not plastic- or rubber-based), could be a contributing feedstock for ethanol and other
biofuels. Using 2005 data, the U.S. EIA calculated that 94 million tons (MT) (about 56 percent)
of the 167.8 MT of MSW waste generated that year had biogenic BTU content (U.S. EIA, 2007).
This estimate included food waste—the third largest component by weight, and a potentially
viable biofuel feedstock in addition to biogenic material listed above. It is estimated by Shi et al
(2009) that at least 21billion gallons of waste paper-derived cellulosic ethanol can be produced
globally from MSW (Shi et al., 2009). While this is not a likely scenario (since, for example,
some of the biogenic fraction—paper, wood, etc.—would be recycled or reused), it demonstrates
that MSW could be a significant source for biofuel. In addition, there are significant
environmental co-benefits associated with using MSW for biofuel, including diverting solid
waste from landfills and incinerators, extending their useful life, and reserving that capacity for
materials that cannot be recycled or reused.
3.6.3. Other Wastes
Several types of waste materials that currently present environmental and economic
challenges have the potential to be harnessed as feedstock for biofuel. These materials include
waste oil and grease, food processing wastes, and livestock waste (Antizar-Ladislao and Turrion-
Gomez, 2008).
The DOE estimates that the restaurant industry generates 9 pounds of waste oil per
person annually, and that the nation's wastewater contains roughly 13 pounds of grease per
person per year (Wiltsee, 1998). Several municipalities and industries have implemented
collection programs, and are converting these wastes to biodiesel.
Annually, the United States generates an estimated 48 million tons of food processing
wastes (i.e., food residues produced during agricultural and industrial operations), not including
food waste disposed and processed through wastewater treatment plants (Kantor et al., 1997).
These wastes have potential as biofuel feedstocks.
The United States generates over 1 billion tons of manure, biosolids, and industrial
byproducts each year (ARS, n.d.). The amount of manure generated at confined and other types
of animal feeding operations in the United States is estimated to exceed 335 million tons of dry
matter per year (ARS, n.d.). While much of this manure is applied to cropland and pasture as
fertilizer, excess is often available and could be tapped as a biofuel feedstock. It has been
23 Specifically, a partnership between the Solid Waste Authority of Central Ohio and Quasar Energy Group to
produce ethanol from municipal solid waste (see http://www.quasarenergygroup.com/pages/home.html), as well as
the "Deploying Renewable Energy—Transforming Waste to Value" grant program (see
http://www.biomassintel.com/ohio-10-million-available-waste-to-energy-grant-program/).
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estimated that around 10 percent of current manure production could be used for bioenergy
purposes under current land use patterns once sustainability concerns are met (i.e., this manure is
available after primary use of manure on soils to maintain fertility) (Perlack et al., 2005).
Methane emissions from livestock manure management systems, which account for a significant
percentage (10 percent or 17.0 million metric tonnes of carbon equivalent [3.0 teragrams] in
1997) of the total U.S. methane emissions, are another potential energy source (U.S. EPA, 1999).
Using any of these excess waste materials as biofuel feedstocks could create a higher-
value use with significant environmental and economic benefits.
3.6.4. Environmental Impacts of Waste-Based Biofuel
Among other environmental benefits, using waste-based biofuels diverts waste from
landfills (avoiding the generation of landfill methane) and diverts waste and trap greases (helping
to avoid costly plant disruptions that contribute to combined sewer overflow). Biorefmeries that
use wastes, particularly MSW, tend to be located near the sources of those wastes; accordingly,
they are also near dense populations of end-users of transportation fuels, which helps reduce the
GHG life cycle footprint of waste-derived fuels (Antizar-Ladislao and Turrion-Gomez, 2008;
Williams et al., 2009).
More information is needed to understand and evaluate the environmental effects of
waste-based biofuels. Different wastes have different characteristics, including size, volume,
heterogeneity, moisture content, and energy value. These characteristics will, to a large degree,
determine feasible and appropriate collection, processing, and conversion methods, which in turn
will determine net energy gain, as well as environmental impacts such as air and GHG
emissions. Research is needed to compare the benefits and impacts of various technological
options for converting MSW to biofuel, and to compare, on a regional basis, the environmental
benefits and impacts of MSW to other biofuel feedstocks. Currently, data are lacking for such
comparisons. Comparative life cycle assessments that consider both the direct impacts or
benefits and indirect impacts or benefits (e.g., impacts of reduced landfilling of MSW) are
needed to understand the true value of waste as an alternative feedstock.
3.6.4.1. Key Findings and Uncertainty
There have been comparatively few attempts at assessing the environmental impacts
associated with the production and use of waste-based biofuels (Williams et al., 2009). In
general, waste as a feedstock is expected to have a smaller environmental impact than
conventional feedstocks. However, the choice of waste management options and the particular
technology for energy recovery will influence the environmental medium impacted and the level
of impact (Chester and Martin, 2009; Kalogo et al., 2007). As the number of waste conversion
facilities increases, environmental monitoring and research will be needed to address the
information gaps that currently limit environmental assessment.
3.7. Summary of Feedstock-Dependent Impacts on Specialized Habitats
EISA Section 204 requires an assessment of the impacts of biofuels on a variety of
environmental and resource conservation issues, including impacts on forests, grasslands, and
wetlands. This section provides an overview of impacts on these specific habitats.
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3.7.1. Forests
Section 21 l(o) of the Clean Air Act limits (CAA) planting of SRWC and harvesting of
tree residue to actively managed tree plantations on non-federal land that was cleared before
December 19, 2007, or to non-federal forestlands; it limits removal of slash and pre-commercial
thinning to non-federal forestlands. However, as described in Table 3-4, a variety of activities
associated with producing woody biomass feedstock may have direct impacts on forests.
While row crop cultivation is not expected to directly affect forests, there may be indirect
effects. Recent economic modeling has predicted a net decrease in the acres of forested lands in
the United States in response to an expansion of cropland needed to satisfy future demand for
ethanol (Keeney and Hertel, 2009; Taheripour et al., 2010; Hertel et al., 2010a, 2010b). Woody
biomass is the feedstock most likely to affect forests in place; algae and most perennial grasses
are unlikely to have an impact on this habitat.
Table 3-4: Overview of Impacts on Forests from Different Types of Biofuel Feedstocks
Feedstock
Row crops
Perennial
grasses
Woody
biomass
Algae
Forest Impact
No direct impacts are likely since the conversion of forests to row crops is ineligible
under RFS2; may have indirect impacts.
Use of forested buffers as conservation practices to control erosion and nutrient
runoff can increase forest habitat and connectivity for some species.
Most grass species are unlikely to have impacts.
Use of forested buffers as a best management practice to control erosion and nutrient
runoff can increase forest habitat and connectivity for some species.
SRWC plantations may deplete soil nutrients with repeated, frequent harvesting,
particularly on marginal soils, but may sustain levels with coppicing, longer
rotations, and strategic use of cover crops.
SRWC plantations can sustain high species diversity, although bird and mammal
species in these plantations tend to be habitat generalists.
Some tree species under consideration, like Eucalyptus, may invade forests in certain
locations.
Harvesting with residue removal can be sustainable for at least one rotation, yet
multiple harvests and removals at the same site may pose a risk to forest growth,
particularly on nutrient-poor soils.
Harvesting forest residues may decrease woody debris available for species habitat.
Unlikely to have any significant impacts.
Report
Section
3.7.1
3.2.8
3.3.4.2
3.4.4
3.4.4.1
3.4.8.1
3.4.8.2
3.4.6.2;
3.2.6.1
3.4.8.1
3.5.1
3.7.2. Grasslands
In addition to the restrictions on forested sources of renewable biomass mentioned above,
Section 21 l(o) of the CAA more broadly limits the lands on which any biofuel feedstock can be
produced to those that were cleared or cultivated at any time before December 19, 2007, either in
active management or fallow and non-forested. Therefore, grassland that remained uncultivated
as of December 19, 2007, is not included in the RFS2 Final Rule and would not be considered
eligible for renewable biomass production. However, in the Midwest approximately 96, 59, and
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50 percent, respectively, of the historical tallgrass, mixed grass, and short grass prairie have
already been converted for human purposes (Samson and Knopf, 1994).
Most of the lands that would be eligible for renewable biomass production under the
CAA, because they were cultivated at some point prior to December 19, 2007, are now part of
the CRP (see Section 3.2.3). Multiple studies project that some conversion of CRP to cropland
will occur (Malcolm et al., 2009; Beach and McCarl, 2010). Because the vast majority of land
enrolled in CRP uses native or introduced grasses (FSA, 2010), it is likely that the conversion of
CRP lands to biomass production will impact grassland ecosystems (Table 3-5). However,
cultivation of perennial grasses in conjunction with conservation practices could have some
positive effects on previously degraded grasslands.
Table 3-5: Overview of Impacts on Grasslands from Different Types of Biofuel Feedstocks
Feedstock
Row crops
Perennial
grasses
Woody
biomass
Algae
Grasslands Impact
Conversion of grasslands (e.g., CRP) to row crops particularly impacts grassland-
obligate species, potentially leading to declines, including declines in duck species.
Higher proportions of corn within grassland ecosystems lead to fewer grassland bird
species.
Use of grassland buffer strips as conservation measures to mitigate erosion and nutrient
runoff will increase grassland area and can provide habitat for some grassland species
depending on management regimes.
Conversion of row crops to switchgrass and use of grassland buffer strips as
conservation measures to mitigate erosion and nutrient runoff may improve grassland
habitat for some species depending on management regimes.
Commercial grassland production as a feedstock may require chemical inputs and can
negatively impact water quality.
Overall biodiversity will be impacted by harvesting and management regimes.
Cultivation of perennial grasses outside their native ranges and/or introduction of more
vigorous varieties of native species could lead to invasions of pastures and native
grasslands.
Unlikely to have significant impacts, since eligible woody biomass is restricted to
managed forest lands under RFS2.
Unlikely to have any significant impacts.
Report
Section
3.2.8.1
3.2.8.1
3.2.4.1
3.3.4.1
3.3.4.3
3.3.8.1
3.3.8.2
3.4.1
3.5.9
3.7.3. Impacts on Wetlands
Provisions in both the Food Security Act of 1985 (commonly known as the Swampbuster
Program) and the Clean Water Act (Section 404 Regulatory Program) offer disincentives that
limit the conversion and use of wetlands for agricultural production. These programs have
reduced the rate of wetland losses due to agricultural development, although some wetlands are
still lost due to partial drainage and indirect effects of altered volume and timing of runoff (Dahl,
2000; Blann et al., 2009). Continued losses of wetlands have consequences for the landscape
mosaic of habitat, reducing connectivity for a variety of organisms (Blann et al., 2009). Current
legislation also does not protect all types and sizes of wetlands, making some (e.g., small,
isolated, or seasonal wetlands) more vulnerable to direct losses or indirect impacts of drainage
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Chapter 3: Environmental Impacts of Specific Feedstocks
(Blann et al., 2009). Therefore, the feedstocks assessed in this report are still expected to impact
wetlands (Table 3-6).
Table 3-6: Overview of Impacts on Wetlands from Different Types of Biofuel Feedstocks
Feedstock
Row crops
Perennial
grasses
Woody
biomass
Algae
Wetlands Impact
Increased sediment, nutrients, chemicals, and pathogens from runoff flow into
downstream wetlands and change wetlands community structure.
Possible loss of or impacts on small, isolated, or seasonal wetlands due to conversion
or partial drainage with consequences for other species.
Increase in wetland habitat if wetlands are constructed to control erosion or nutrient
runoff.
Reduced sediment and nutrient loadings, leading to improved water quality (but
dependent on specific management practice).
Some grass species under consideration may invade wetlands, including giant reed
(Arundo donax) and reed canary grass (Phalaris amndinacea).
Possible loss of or impacts on small, isolated or seasonal wetlands due to conversion
or partial drainage with consequences for other species.
SRWC plantations can initially increase runoff of nutrients and sediment to water
bodies, yet these losses rapidly decline to low levels after the establishment phase.
Algal strains created may escape from cultivation, potentially affecting wetlands.
Report
Section
3.2.4
3.2.8;
3.7.3
3.2.4.1
3.3.4.1;
3.3.4.2
3.3.8.2
3.3.8;
3.4.4.1
3.5.8.2
3.8. Genetically Engineered Feedstocks
Genetic engineering of crops has a history of research, development, and
commercialization that extends back for more than 15 years. Along with the growth of this
biotechnology industry, the United States established a coordinated framework for regulatory
oversight in 1986 (OSTP, 1986). Since then, the relevant agencies (EPA, USD A, and the Food
and Drug Administration) have implemented risk assessment programs that allow informed
environmental decision-making prior to commercialization. These programs have been
independently assessed over the years (NRC, 2000, 2001, 2002) and improvements made to
ensure the safety of the products. At the same time, the methodology for biotechnology risk
assessment has been scrutinized and general frameworks created to facilitate robust approaches
and harmonize the processes internationally (Conner et al., 2003; Pollard et al., 2004; Andow
and Zwalen, 2006; Raybould, 2007; Auer, 2008; Craig et al., 2008; Nickson, 2008; Romeis et al.,
2008;). Nonetheless, there are environmental concerns associated with genetically modified
organisms (GMOs) that are currently used as biofuel feedstocks, as well as anticipated concerns
for GMOs that will be developed for the next generation of biofuel feedstocks.
Brookes and Barfoot (2006, 2008, 2009, 2010) conducted a series of extensive post-
commercialization assessments of genetically engineered maize, soybeans, cotton, sugar beets,
and canola varieties at 10-year intervals. In these analyses, the authors found consistent
reductions in the amounts of pesticides used and a reduction in GHG emissions for agricultural
systems where these GMO crops are grown. These results are supported by others (Brinmer et
al., 2005; Knox et al., 2006), although regional differences in the reductions have been noted
(Kleter et al., 2008). The results for corn and soybean are consistent with the general trends
(Brookes and Barfoot, 2010). Assuming that current genetically engineered varieties of corn and
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soybeans receive continued regulatory oversight, no additional environmental concerns are
anticipated with these organisms in their current genetic configuration, even with an increase in
their production. However, as feedstocks for biofuel change to accommodate cellulosic
technologies and algae production, the range of environmental considerations, including impacts
from GMO varieties, will change as well (Wilkinson and Tepfer, 2009; Lee et al., 2009).
To harness the full potential of biomass, the genetic engineering of feedstocks has been
recognized as a key technology (Gressel, 2008; Antizar-Ladislao and Turrion-Gomez, 2008;
Sexton et al., 2009). The approaches being considered include increasing plant biomass by
delaying flowering, altering plant growth regulators, and manipulating photosynthetic processes;
modifying traits (e.g., herbicide tolerance, insect resistance) in non-row crop plants that reduce
cultivation inputs; and modifying cellulose/lignin composition and other traits that result in cost
reductions in bioprocessing (i.e., facilitating the biorefmery process) (Sticklen, 2007, 2009;
Ragauskas et al., 2006; Gressel, 2008). These new varieties may have implications for the
environment beyond what has been considered in first-generation biotechnology crops, and the
scientific community has begun to examine whether and how well existing risk assessment
procedures will work for bioenergy crops (Chapotin and Wolt, 2007; Firbank, 2007; Lee et al.,
2009; Wilkinson and Tepfer, 2009; Wolt, 2009).
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
4. BIOFUEL PRODUCTION, TRANSPORT, STORAGE, AND END USE
4.1. Introduction
This chapter addresses potential environmental impacts of post-harvest activities of the
biofuel supply chain (see Figure 4-1). These activities comprise feedstock logistics (Section 4.2)
and biofuel production (including handling of wastes and byproducts) (Section 4.3), distribution
(Section 4.4), and end use (Section 4.5).
Production of biofuel from feedstock takes place at biofuel production facilities through a
variety of conversion processes. The biofuel is transported to blending terminals and retail
outlets by a variety of means, including rail, barge, tankers, and trucks. Biofuel distribution
almost always includes periods of storage. Once dispensed at the final outlet, biofuel is
combusted in vehicles and other types of engines, usually as a blend with gasoline or diesel, or in
some cases in neat form.
Feedstock
Production
Land Use/
Conversion
Feedstock
Cultivation &
Harvest
Feedstock
Logistics
Transport, Storage &
Distribution
Biofuel
Production
Conversion of
Feedstock to
Biofuel
Biofuel
Distribution
Handling, Blending,
Transport & Storage
Vehicle Fueling &
Operation
Figure 4-1: Biofuel Supply Chain and Use of Biofuel
Biofuel production, distribution, and end use primarily affect air and water, with some
consequences for aquatic ecosystems. Air emissions may be released by a variety of sources.
Many factors affect the quantity and characteristics of these emissions, including the type and
age of equipment used, and operating practices and conditions.
Air emissions associated with end use of ethanol combustion are relatively independent
of feedstock or conversion process, whereas biodiesel emissions are highly dependent on
feedstock type. As discussed later in the chapter, biofuel combustion may result in higher
emissions of some pollutants compared to gasoline combustion, and lower emissions of others.
Biofuel production requires the use of water, which may contribute to ground water
depletion or lower surface water flow, depending on the amount of water withdrawn and water
availability. Potential water quality impacts include wastewater discharge during the conversion
process and the potential for leaks and spills to surface and ground water during biofuel
handling, transport, and storage. Additionally, phosphorus runoff from the manure of animals
that have been fed an ethanol byproduct—for example, dried distillers grains with solubles,
which have a high phosphorus content (Regassa et al., 2008)—may have the potential to impact
water quality and aquatic ecosystem condition.
Possible air and water impacts associated with ethanol and biodiesel, as well as
opportunities for mitigation, are discussed in Sections 4.2 to 4.5. Discussion focuses primarily on
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
the impacts of corn ethanol and diesel from soybean oil, because these constitute the vast
majority of biofuel produced and used in the United States as of July 2010.
4.2. Feedstock Logistics
4.2.1. Handling, Storage, and Transport
Feedstock logistics comprise activities associated with handling, storing, and transporting
feedstocks after harvest to the point where the feedstocks are converted to biofuel. Though
alternative feedstock logistic systems have recently been proposed—e.g., the Uniform-Format:
Solid Feedstock Supply System (Hess et al., 2009a)—this report considers the conventional
system of transporting biomass directly to refinery without prior processing. The most significant
environmental impacts of these activities are the emissions associated with energy use. Both
greenhouse gases (GHGs) and criteria pollutant emissions result from the combustion of fuels
used during transportation. In general, feedstock logistics may be optimized, and emissions
reduced, by integrating feedstocks, processing facilities, and consumer demands at a regional
scale to minimize transport distances.
4.2.1.1. Ethanol
Harvested corn is transported to a biorefinery, where it is converted to ethanol and a
number of co-products. Air quality will be impacted by emissions from the combustion of fuels
used for transportation vehicles and equipment.
4.2.1.2. Biodiesel
After harvest, soybeans or other vegetable oil seeds used as biodiesel feedstocks are
transported from fields to the drying site, storehouse, or collection center, followed by transport
to the biodiesel refinery. In the case of soybeans, mechanical crushing is typically used to
separate soybean hulls from soybean oil. Air quality may be affected by emissions from the
combustion of fuels used for transportation vehicles and equipment.
4.3. Biofuel Production
4.3.1. Biofuel Conversion Processes
4.3.1.1. Ethanol
As of November 2009, there were 180 corn starch ethanol facilities in the United States
9/1
with a combined capacity of 12 billion gallons per year (bgy) (U.S. EPA, 2010a). At that time,
27 of these (representing 1,400 million gallons per year [mgy] of capacity) were idled, and
another 10 facilities (representing a combined capacity of 1,301 mgy), were under construction
(U.S. EPA, 2010a). The majority of corn starch ethanol facilities are located in the country's
24 Sources include the Renewable Fuels Association's Ethanol Biorefinery Locations (updated October 22, 2009)
and Ethanol Producer Magazine's producing plant list (last modified on October 22, 2009), in addition to
information gathered from producer websites and follow-up correspondence.
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
major corn-producing states: Iowa (with the largest production capacity and the greatest number
of plants) followed by Nebraska, Minnesota, Indiana, and Illinois (U.S. EPA, 2010a).
Conventional ethanol is produced from the fermentation of corn starch. Two methods are
currently used:
• Dry milling, in which the corn kernel is first ground into a meal, usually without
separating out the various component parts of the grain. The meal is then slurried
with water and cooked at high temperatures to form a mash, which then
undergoes fermentation. Dry milling is more commonly used than wet milling.
• Wet milling, in which the kernels are steeped in water to separate out the germ,
fiber, and gluten (fractionation). From this initial separation, co-products such as
corn meal, corn gluten meal, and corn gluten feed are recovered. The remaining
mash contains the water-soluble starch, which undergoes further processing for
biofuel.
In both processes, soluble starch is subsequently converted to a simple sugar (glucose)
through saccharification, an enzyme-catalyzed hydrolysis reaction. This is followed by yeast
fermentation of the glucose to ethanol. Following fermentation, the mash is distilled to collect
the ethanol as a mixture of 95 percent alcohol and 5 percent water. A subsequent dehydration
step is required to remove the aqueous portion to yield 99.5 percent pure ethanol. Efforts to
improve conversion efficiency have resulted in increased ethanol yields per bushel of corn. A
2008 survey of dry mill corn ethanol plants reported requiring 5.3 percent less corn than in 2001
to produce an equivalent amount of ethanol (Mueller, 2010).
Substantial efforts are under way to develop processes to convert feedstocks containing
cellulose into biofuels. These cellulosic feedstocks are primarily composed of cellulose,
hemicellulose, and lignin polymers. Currently, two major pathways exist for converting
cellulosic feedstocks into biofuel:
• Biochemical conversion using a physical and chemical process to liberate tightly
bound cellulose and hemicellulose from lignin. The process uses strong acid or
enzymes (cellulases) to hydrolyze the cellulose and hemicelluloses to glucose and
other simple sugars, followed by microbial fermentation of the sugars into
ethanol.
• Thermochemical conversion involving gasification or pyrolysis.
— In the gasification process, biomass is heated at high temperatures with a
controlled amount of oxygen to decompose the cellulosic material. This
yields a mixture composed mainly of carbon monoxide and hydrogen
known as syngas.
— In. pyrolysis, the biomass is heated in the absence of oxygen at lower
temperatures than used in gasification. The product is a liquid bio-oil that
can be used subsequently as a feedstock for a petroleum refinery.
Other cellulosic conversion processes are in various stages of development, from concept
stage to pilot-scale development to construction of demonstration plants. Although no U.S.
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
commercial-scale plants are operating as of July 2010, several companies are expected to have
facilities operating within the next few years.
4.3.1.2. Biodiesel
As of November 2009, there were approximately 191 biodiesel facilities in the United
States, with a combined capacity of 2.8 bgy (U.S. EPA, 2010a). Total domestic production of
biodiesel in 2009 was 505 mgy—much less than domestic production capacity. The dominant
technology used to produce biodiesel involves a transesterification reaction in which
triglycerides (fats) from the oil are converted to esters in the presence of an alcohol and a catalyst
such as potassium hydroxide. Plant oils (soy, algae, etc.) and other feedstocks (e.g., animal-
derived oil such as lard and tallow, recycled oil and grease from restaurants and food processing
plants) provide sources of triglycerides for conversion to biodiesel. Free glycerol, or glycerin, is
a major co-product in transesterification, constituting an estimated 10 percent of the final product
(U.S. EPA, 2010a). Table 3-2 shows the breakdown of feedstocks used to produce biodiesel in
the United States in 2009. Vegetable oils, including soybean oil, made up the majority of
biodiesel feedstock—nearly 60 percent.
Commercial processes for large-scale algae production and algal oil collection are
currently being developed as another plant oil source for biodiesel (U.S. EPA, 2010a). Lipid
extraction and drying currently are energy-intensive steps in the algae diesel production process.
Other processing techniques are currently being investigated, including enzymatic conversion
and catalytic cracking of algal oil, pyrolysis, and gasification of algae. However, lipid extraction
via solvents followed by transesterification remains the most commonly used method for algal
oil processing (U.S. DOE, 2010). Until commercial facilities using mature technologies go into
production, the impacts from algae conversion will be uncertain.
In addition to transesterification, other methods for converting seed oils, algal oils, and
animal fats into biofuel have been developed recently using technologies that are already widely
employed in petroleum refineries (Huo et al., 2009). Hydrotreating technologies use seed oils or
animal fats to produce an isoparaffm-rich diesel substitute referred to as "green diesel" or
renewable diesel, which is distinctly different from biodiesel, which is generated using the
transesterification process (Huo et al., 2008).
Although the transesterification process can generate much more diesel product than the
other processes, as noted above, it requires more energy and chemical inputs (Huo et al., 2008).
In some cases, inputs, which are very energy-intensive to produce, must also be taken into
consideration in a full life cycle assessment in order to adequately evaluate energy efficiency of
each fuel production process. Compared with conventional diesel and biodiesel, renewable diesel
fuels have much higher cetane numbers—a measure of diesel fuel quality (Huo et al., 2008).
4.3.2. Air Quality
The net changes in volatile organic compounds (VOCs), carbon monoxide (CO), nitrogen
oxides (NOX), and particulate matter (PM) emissions associated with biofuel production can be
attributed to two countervailing effects: (1) emission increases connected with biofuel production
and (2) emission decreases associated with reductions in gasoline production and distribution as
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ethanol displaces gasoline. EPA (2010a) determined that increases in fine particles less than 2.5
micrometers in diameter (PM2.s), sulfur oxide (SOX), and especially NOX were driven by
stationary combustion emissions from the substantial increase in corn and cellulosic ethanol
production.
Increasing the production and distribution of ethanol was also found to lead to higher
ethanol vapor emissions. To a lesser degree, the production and distribution of greater amounts
of ethanol would lead to increases in emissions of formaldehyde and acrolein, as well as very
small decreases in benzene, 1,3-butadiene, and naphthalene emissions relative to the total
volume of these emissions in the United States. Additional details on EPA's analysis of changes
in emissions associated with the revised Renewable Fuels Standard program (RFS2) volumes can
be found in www.epa.gov/otaq/fuels/renewablefuels/regulations.htm.
Air pollutant emissions associated with the conversion of biomass to fuel may be
mitigated through the use of cleaner fuels during the conversion process and more efficient
process and energy generation equipment. The majority of ethanol plants built in recent years,
and expected to be built in the near future, use dry mill technology (Wang et al., 2007a). Because
they use similar production processes, differences in environmental impacts between plants are
primarily due to each plant's choice of fuel. EPA's RFS2 Regulatory Impact Analysis (RIA)
assumes a dry mill for the base scenario.
EPA's RFS2 RIA examines the impacts of using energy-saving technologies such as
combined heat and power (CHP). CHP is an effective means to reduce air emissions associated
with biofuel production (both ethanol and biodiesel). CHP generates electricity by burning
natural gas, biogas, or byproducts such as lignin, and then employs a heat recovery unit to
capture heat from the exhaust stream as thermal energy. Using energy from the same fuel source
significantly reduces the total fuel used by facilities along with the corresponding emissions of
carbon dioxide (CO2) and other pollutants. Fractionation, membrane separation, and raw starch
hydrolysis are additional technologies examined in EPA's RFS2 RIA that increase process
efficiencies by enabling producers to sell distillers grains (a co-product of the corn-ethanol
conversion process) wet rather than dry, thereby reducing GHG emissions and other possible
environmental impacts (since drying distillers grains is an energy-intensive process).
4.3.2.1. Ethanol
Ethanol production requires electricity and the use of steam. Electricity is either
purchased from the grid or produced on site, and steam is typically produced on site from natural
gas. Power and the energy used to fuel boilers are responsible for emissions of VOCs, PM, CO,
SOX and NOX (U.S. EPA, 2010a; Wang et al., 2007b). For corn-based ethanol, fossil fuels such as
natural gas are typically used to produce heat during the conversion process, although a number
of corn ethanol facilities are exploring new technologies with the potential to reduce their energy
requirements. A 2008 survey of dry corn mill ethanol plants highlighted recent efficiency gains.
The survey reported that, compared to 2001, ethanol produced in 2008 required 28.2 percent less
thermal energy and 32.1 percent less electricity (Mueller, 2010). A continuation of such
efficiency improvements could further reduce the environmental impacts of ethanol production.
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A number of processes at ethanol production facilities result in emissions of air toxics.
These processes include fermentation, distillation of the resultant mash, and drying of spent wet
grain to produce animal feed. Emissions of air toxics vary tremendously from facility to facility
due to a variety of factors, and it is difficult to determine how differences in the production
processes individually impact emissions (U.S. EPA, 2010a). Ethanol vapor and air toxic
emissions associated with biofuel production were projected to increase in EPA's RFS2 RIA, but
these increases would be very small compared to current emissions (U.S. EPA, 2010a).
4.3.2.2. Biodiesel
While the production processes for biodiesel and ethanol are fundamentally different,
both require thermal and electrical energy for production. The thermal energy required for
biodiesel production is usually met using steam generated using a natural gas boiler. In certain
situations, the glycerol co-product may also be burned to produce process heat, or a biomass
boiler may be used to replace natural gas.
Air quality issues associated with a natural gas-fired biodiesel production process are
similar to those for other natural gas applications such as ethanol production, and include
emissions of VOCs, PM, CO, SOx, and NOX. Glycerol or solid fuel biomass boilers have
emissions characteristics similar to those anticipated for cellulosic ethanol plants, including
increased particulates and the potential for VOCs, NOX, and SOX.
Biodiesel production using a closed hot oil heater system would have none of the air
emissions associated with traditional steam production. Air emissions associated with these
systems would be associated with the production of the electricity, which would take place
outside the biodiesel plant boundary.
Additionally, the extraction of vegetable oil to create biodiesel in large chemical
processing plants is typically achieved using hexane, a VOC that EPA has classified as a
hazardous air pollutant. Hexane is also commonly used to extract algal oils. Fugitive emissions
of hexane may result from increased biodiesel manufacture (Hess et al., 2009a).
4.3.3. Water Quality and Availability
All biofuel facilities use process water to convert biomass to fuel. Water used in the
biorefming process is modest in absolute terms compared to the water applied and consumed in
growing the plants used to produce biofuel. However, the use of water at production facilities
may be locally significant, whereas agricultural water use may be more geographically dispersed.
The impacts associated with water use at conversion facilities depend on the location of the
facility in relation to water resources. In some regions where water is abundant, increased
withdrawals may have little effect. Ground water depletion may result in increased costs to pump
water from deeper wells, loss of stream flow, and subsidence of the overlying land (Reilly et al.,
2008). Several areas of the country that are already experiencing lowered ground water levels
(e.g., the High Plains aquifer, the Lower Mississippi River alluvial aquifer) correspond with
regions where increased biofuel production is expected. In addition, minimum in-stream flow for
aquatic life can be affected by ground water depletion because ground water discharge into
streams is a major source of stream base flow. In some areas, streams have run dry due to ground
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water depletion, while in other areas, minimum stream flow during the summer has been
sustained because of irrigation return flow to streams (Bartolino and Cunningham, 2003). In the
case of sole source aquifers, ground water depletion may severely impact drinking water
availability, because these areas have no readily available alternative freshwater sources (Levin
et al., 2002).
Comprehensive local, state, and regional water planning, as well as state regulatory
controls, are critical to ensure that facilities are located in watersheds that can sustain the
increased withdrawal without affecting other uses. Siting of biofuel facilities may also be
influenced by state laws and regulations designed to avoid or mitigate conflicts among water
uses. These vary by state. For example, withdrawals associated with biofuel production facilities
may need a state permit to ensure that the proposed withdrawal does not result in unacceptable
impacts on other users or on aquatic life. In addition, different states assign water rights in
different ways. Some exercise the prior appropriation rule (i.e., water rights are determined by
priority of beneficial use, meaning that the first person to use the water can acquire individual
rights to the water); some are based on the English law of absolute ownership (i.e., rights to use
water are connected to land ownership); some limit withdrawals based on stream flow
requirements for aquatic life; and some have a hierarchy to prioritize uses of the water.
Like water quantity impacts, water quality impacts depend on a number of factors
including facility location, water source, receiving water, type of feedstock used, biorefinery
technology, effluent controls, and water re-use/recycling practices. Water quality impacts are
associated with the wastewater discharge from the conversion process. Pollutants of concern
discharged from ethanol facilities include biological oxygen demand (BOD), brine, ammonia-
nitrogen, and phosphorus. BOD, glycerin, and to a certain extent, total suspended solids (TSS)
are primary pollutants of concern found in biodiesel facility effluent. Regulatory controls placed
on the quality of biofuel production wastewater discharge can mitigate some water quality and
aquatic ecosystem impacts. Discharges to publicly owned wastewater treatment works (POTWs)
are subject to general pre-treatment standards (40 CFR 403.5) in the Clean Water Act. Biofuel
facilities that discharge their wastewater to POTWs are subject to pre-treatment limitations that
are in effect for the receiving POTW. For those facilities that treat and discharge their own
wastewater, EPA has enforceable regulations to control production facility effluent discharges of
BOD, sediment, and ammonia-nitrogen through the National Pollutant Discharge Elimination
System (NPDES) permit program.
Whether effluent is discharged to a POTW or treated on site at the production facility,
BOD can lead to methane emissions during the wastewater treatment process. To mitigate the
release of methane to atmosphere, facilities can install anaerobic digesters as a treatment step.
Anaerobic digesters treat the biosolids contained in wastewater effluent, generating biogas that is
approximately 60 to 65 percent methane. This biogas can then either be flared or captured and
used as a clean energy source at the biofuel production facility or elsewhere.
Currently there are no effluent limitation guidelines or categorical pretreatment standards
that regulate process wastewater discharges from ethanol and biodiesel manufacturing facilities.
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4.3.3.1. Ethanol
In 2007-2008, EPA evaluated biodiesel and corn ethanol manufacturing facilities. No
major effluent quality issues were found from corn ethanol plants discharging to either surface
waters or to wastewater treatment plants.
While some ethanol facilities get their process water from municipal water supplies, most
use onsite wells (Wu et al., 2009). However, most untreated ground water sources are generally
not suitable for process water because of their mineral content. Ground water high in mineral
content is commonly treated by reverse osmosis, which requires energy and concentrates ground
water minerals into reject water, with potential water quality impacts upon their release. For
every two gallons of pure water produced, about a gallon of brine is discharged as reject water
(U.S. EPA, 2010a). Methods to reduce the impact associated with reject water high in mineral
concentration include (1) further concentration and disposal or (2) use of in-stream dilution.
Some ethanol facilities have constructed long pipelines to access additional water sources to
dilute the effluent to levels that meet water quality standards.
Once process water is treated, most is lost as steam during the ethanol production
process. Water use varies depending on the age of the facility and the type of milling process.
Older generation production facilities use 4 to 6 gallons of process water to produce a gallon of
ethanol; newer facilities generally use less than 3. Most of this water savings is gained through
improved recycling of water and heat in the process. Dry milling facilities consume on average
3.45 gallons of fresh water per gallon of ethanol produced (Wu, 2008); newer facilities tend to
consume about 21 percent less water (Wu et al., 2009). Wet mill facilities consume an average of
3.92 gallons of fresh water per gallon of ethanol produced (Wu, 2008). Most estimates of water
consumption in ethanol production are based on the use of clean process water and do not
include the water discharged as reject water.
Ethanol plants are designed to recycle water within the plant, and improvements in water
use efficiency of ethanol facilities are expected through steam condensate reuse and treated
process water recycling (Wu et al., 2009). Continued development of new technologies that
improve water efficiency will help mitigate water quantity impacts.
Because no large-scale cellulosic ethanol production facilities are currently operating,
water demand for production of cellulosic ethanol is not certain. However, for most cellulosic
feedstocks, including agricultural residues like corn stover and dedicated energy crops like
switchgrass, water demand is estimated to be between 2 and 10 gallons of water per gallon of
ethanol, depending on the conversion technology, with volumes greater than 5 gallons of water
per gallon of ethanol cited more often (NRC, 2008; Williams et al., 2009; Wu et al., 2009). Some
studies assume water demand for processing woody biomass will be similar to processing
cellulosic material from agricultural residues or dedicated energy crops (up to 10 gallons of
water per gallon of ethanol) (Evans and Cohen, 2009). Other studies state that new technologies
like fast pyrolysis will require less than half that amount of water per gallon of ethanol (Wu et
al., 2009). Consumptive use of water is declining as ethanol producers increasingly incorporate
recycling and other methods of converting feedstocks to fuels that reduce water use (NRC, 2008;
Laser et al., 2009).
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Cellulosic ethanol facilities that employ biochemical conversion would be expected to
have similar water requirements and brine discharges as the current operating corn ethanol
facilities. The additional steps required to separate the lignin from the cellulose could produce
wastewater streams high in BOD that would require treatment on site or at wastewater treatment
plants.
4.3.3.2. Distillers Grain with Solubles
One important co-product of ethanol production is dried distillers grain with solubles
(DDGS). Due to the increase in ethanol production and the prices of corn and soybeans, DDGS
has become an increasingly important feed component for confined livestock. About one-third of
the corn processed into ethanol is converted into DDGS; therefore, approximately 45 million
tons of DDGS will be produced in conjunction with the 15 billion gallons of corn ethanol
produced by 2015.
Livestock producers may partially replace corn or other feeds with DDGS for both
economic and production reasons. Different livestock species can tolerate varying amounts of
DDGS in their diets. Although specific analysis of DDGS can vary among ethanol plants, DDGS
are higher in crude protein (nitrogen) and three to four times higher in phosphorus compared to
corn (Regassa et al., 2008).
The increase in nitrogen and phosphorus from DDGS in livestock feed has potential
implications for water quality and aquatic ecosystems. When nitrogen and phosphorus are fed in
excess of animals' needs, excess nutrients are excreted in urine and manure. Livestock manure
may be applied to crops, especially corn, as a source of nutrients. When manure is applied at
rates above the nutrient needs of the crop or when the crop cannot use the nutrients, the nitrogen
and phosphorus can run off to surface waters or leach into ground waters. Excess nutrients from
manure nutrients have the same impact on water quality as excess nutrients from other sources.
Livestock producers may limit the potential pollution from manure applications to crops
through a variety of techniques. USD A's Natural Resources Conservation Service (NRCS) has
developed a standard for a comprehensive nutrient management plan to address the issue of
proper use of livestock manure (NRCS, 2009).
4.3.3.3. Biodiesel
Biodiesel facilities use much less water than ethanol facilities to produce biofuel. The
primary consumptive water use at biodiesel plants is associated with washing and evaporative
processes. Water use is variable, but is usually less than one gallon of water for each gallon of
biodiesel produced (U.S. EPA, 2010a); some facilities recycle washwater, which reduces overall
water consumption (U.S. EPA, 2010a). However, water use has been reported as high as 3
gallons of water per gallon of biodiesel (Pate et al., 2007). Larger well-designed facilities use
water more sparingly, while smaller producers tend to use more water per production volume
(U.S. EPA, 2010a). New technologies that improve water efficiency will help mitigate water
quantity impacts. Recent plant designs have included either waterless processes or water
recycling.
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In addition to water use in the washing and evaporation processes, sources of wastewater
include steam condensate; process water softening and treatment to eliminate calcium and
magnesium salts, iron, and copper; and wastewaters from the glycerin refining process (U.S.
EPA, 2008c). In a joint U.S. Department of Energy (DOE)/USDA study, it was estimated that
consumptive water use at a biodiesel refinery accounts for approximately one-third of the total
water use, or about 0.32 gallons of water per gallon of biodiesel produced (Sheehan et al.,
1998b). New technologies have reduced the amount of wastewater generated at facilities. Process
wastewater disposal practices include direct discharges (to waters of the United States), indirect
discharges (to wastewater treatment plants), septic tanks, land application, and recycling (U.S.
EPA, 2008c).
Most biodiesel manufacturing processes result in the generation of process wastewater
with free fatty acids (as soap) and glycerin (a major co-product of biodiesel production);
however, the quantity of wastewater will be significantly reduced for facilities with waterless
processes or water recycling. Despite the existing commercial market for glycerin, the rapid
development of the biodiesel industry caused a glut of glycerin production, which resulted in
many facilities disposing of glycerin. Glycerin disposal may be regulated under several EPA
programs, depending on the practice. Glycerin can be marketed as a feedstock following
methanol recovery and additional refining. Significant research on alternative beneficial uses for
glycerin is ongoing (U.S. EPA, 2008a). Some potential options for the catalytic and biological
conversion of glycerin into value-added products, included bio-based alternatives to petroleum-
derived chemicals, have been identified (Johnson and Taconi, 2007).
Other constituents in the wastewater of biodiesel manufacturing include: organic residues
such as esters, soaps, inorganic acids and salts, traces of methanol, and residuals from process
water softening and treatment (U.S. EPA, 2008c). Solvents used to extract lipids from algae,
including hexane, alcohols, and chloroform, could also impact water quality if discharged to
surface or ground water. Typical wastewater from biodiesel facilities has high concentrations of
conventional pollutants—BOD, TSS, oil, and grease—and also contains a variety of non-
conventional pollutants (U.S. EPA, 2008c).
Some biodiesel facilities discharge their wastewater to POTWs for treatment and
discharge. In some cases, wastewater with sufficiently high glycerin levels has disrupted
wastewater treatment plant function (U.S. EPA, 2010a). There have been several cases of
treatment plant upsets due to high BOD loadings from releases of glycerin (U.S. EPA, 2010a).
To mitigate wastewater issues, some biodiesel production systems reclaim glycerin from the
wastewater. As another option, closed-loop systems in which water and solvents can be recycled
and reused can reduce the quantity of water that must be pretreated before discharge.
4.3.4. Impacts from Solid Waste Generation
Biofuels may also lead to significant environmental impacts stemming from solid waste
generated by various production processes. EPA defines "solid wastes" as any discarded
material, such as spent materials, byproducts, scrap metals, sludge, etc., except for domestic
wastewater, nonpoint-source industrial wastewater, and other excluded substances (U.S. EPA,
2010e). Further study is needed to investigate this potential hazard and to examine mitigation
strategies.
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4.4. Biofuel Distribution
The vast majority of biofuel feedstocks and finished biofuel are currently transported by
rail, barge, and tank truck. Ethanol and biodiesel are both generally blended at the end of the
distribution chain, just before delivery to retail outlets. Storage of biofuels typically occurs in
above-ground tanks at blending terminals, in underground storage tanks (USTs), and at retail
outlets (as a petroleum-biofuel blend).
The primary impacts related to transport and storage of biofuels relate to air quality (i.e.,
emissions from transport vehicles and evaporative emissions) and water quality (i.e., leaks and
spills). It should be noted that these impacts are not unique to ethanol and biodiesel, but are
associated with the storage, distribution, and transportation system of all fuels.
4.4.1. Air Quality
4.4.1.1. Ethanol
Air pollution emissions associated with distributing fuel come from two sources: (1)
evaporative, spillage, and permeation emissions from storage and transfer activities and (2)
emissions from vehicles and pipeline pumps used to transport the fuels (see Figure 4-1).
Emissions of ethanol occur both during transport from production facilities to bulk terminals, and
after blending at bulk terminals.
Although most ethanol facilities are concentrated in the midwestern United States,
gasoline consumption is highest along the East and West Coasts. Fleet transport of biofuel, often
by barge, rail, and truck, increases emissions of air pollutants such as CC>2, NOX, and PM due to
the combustion of fuels by transport vehicles. EPA's RFS2 RIA found relatively small increases
in criteria and air toxics emissions associated with transportation of biofuel feedstocks and fuels
(U.S. EPA, 2010a). In addition, transport and handling of biofuel may result in small but
significant evaporative emissions of VOCs (Hess et al., 2009a). With the exception of benzene
emissions, which were projected to decrease slightly, EPA's RFS2 RIA projected relatively
small increases in emissions of air pollutants associated with evaporation (U.S. EPA, 2010a).
Pipeline transport decreases air emissions associated with fleet transport of biofuel
because fuel is not combusted in the transport process. However, transport of biofuels by
pipeline raises potential technical issues, including internal corrosion and stress corrosion
cracking in pipeline walls, and the potential to degrade performance of seals, gaskets, and
internal coatings. Additionally, ethanol's solvency and affinity for water can generate concerns
about product contamination (U.S. EPA, 2010a). Dedicated ethanol pipelines may alleviate these
issues; however, they are costly to construct. Due to the incompatibility issues with the existing
petroleum pipeline infrastructure, the growth in ethanol production is expected to increase
emissions of criteria and toxic air pollutants from freight transport, while a corresponding
decrease in gasoline distribution would decrease emissions related to pipeline pumping (Hess et al.,
2009a).
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4.4.1.2. Biodiesel
Air pollution emissions from fuel combustion in transport vehicles related to biodiesel
feedstocks and fuels are not materially different than those associated with ethanol. Currently,
pipeline distribution of biodiesel is still in the experimental phase. Significant evaporative
emissions are not expected from storage and transport of biodiesel fuel due to its low volatility
(U.S. EPA, 2010a).
4.4.2. Water Quality
Leaks and spills from above-ground, underground, or transport tanks may occur during
biofuel transport and storage, potentially contaminating ground water, surface water, or drinking
water supplies.
For bulk transport, the major concern is based on an accident scenario in which the
transport tank is damaged and a large amount of fuel is spilled. In addition, leaks might occur
during transport because of certain fuel-related factors, such as the fuel's corrosivity. Ethanol is
slightly acidic and can corrode some active metals; biodiesel is also slightly corrosive. The
possibility of leaks during transport is minimized by the selection of appropriate materials and
proper design in accordance with the applicable material standards.
Leaks from USTs are also a major concern. Most states report that USTs are a major
source of ground water contamination (U.S. EPA, 2000). Releases of biofuels blended with
petroleum fuels can migrate to ground and surface water and contaminate drinking water
sources. Other health and environmental risks, including the potential for vapor intrusion, are
also associated with leaking USTs. Although it is not possible to quantify the risk at this time,
EPA is developing modeling software to assess ground water impacts from fuels of varying
composition (U.S. EPA, 2010a).
EPA's Office of Underground Storage Tanks is working with other agencies to better
understand material compatibility issues associated with UST systems, in order to assess the
ability of these systems to handle new fuel blends (U.S. EPA, 2009b). Because most of the
current underground storage tank equipment, including approximately 600,000 active USTs, was
designed and tested for use with petroleum fuels, many UST system components currently in use
may be constructed of materials that are incompatible with ethanol blends greater than 10 percent
(U.S. EPA, 2009c) or biodiesel blends greater than 20 percent (NREL, 2009a).
Several measures are already in place to help prevent and mitigate potential water quality
impacts. Under the Resource Conservation and Recovery Act (RCRA), owners and operators of
regulated UST systems must comply with requirements for financial responsibility, corrosion
protection, leak detection, and spill and overfill prevention. Federal regulations require that
ethanol and biodiesel storage containers are compatible with the fuel stored. For USTs, leak
detection equipment is required and must be functional. Through the Spill Prevention, Control,
and Countermeasure (SPCC) rule, EPA has enforceable regulations to control water quality
impacts from spills or leaks of biofuel products and byproducts.
Additional details specific to ethanol and biodiesel are discussed below.
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4.4.2.1. Ethanol
Ethanol is stored in neat form at the production facility, in denatured form at terminals
and blenders, and as E85 (nominally 85 percent ethanol and 15 percent gasoline) and E10 (10
percent ethanol and 90 percent gasoline) mixtures at retail facilities. There is growing availability
of blender pumps, primarily in the Midwest, where the consumer can select the desired blend of
ethanol in a flex-fuel vehicle. Although there are limited data on the compatibility of storage
tanks with ethanol blends greater than 10 percent, studies indicate that mid-level ethanol blends
may be more degrading to some materials than the lower ethanol blends (NREL, 2009b).
There are unique fate and transport implications associated with releases of ethanol-
gasoline blends compared to releases of gasoline without ethanol. Ethanol is water soluble and
can be degraded by microorganisms commonly present in ground water (U.S. EPA, 2009d). In
ground water, ethanol's high oxygen demand and biodegradability changes the attenuation of the
constituents in ethanol-gasoline blends. This can cause reduced biodegradation of benzene,
toluene, and xylene (up to 50 percent for toluene and 95 percent for benzene) (Mackay et al.,
2006; U.S. EPA, 2009d). The presence of ethanol can restrict the rate and extent of
biodegradation of benzene, which can cause the plumes of benzene to be longer than they would
have been in the absence of ethanol (Corseuil et al., 1998; Powers et al., 2001; Ruiz-Aguilar et
al., 2002). This could be a significant concern to communities that rely on ground water supplies
with the potential to be impacted by leaks or spills (Powers et al., 2001; Ruiz-Aguilar et al.,
2002). In surface waters, rapid biodegradation of ethanol can result in depletion of dissolved
oxygen with potential mortality to aquatic life (U.S. EPA, 2010a).
There are other potential hazards in addition to those associated with chemical toxicity.
Some spills of ethanol-gasoline blends may produce methane concentrations in the soil that pose
a risk of explosion (Da Silva and Alvarez, 2002; Powers et al., 2001).
4.4.2.2. Biodiesel
In general, if biodiesel is blended with petroleum diesel, another petroleum product, or a
hazardous substance, then state UST regulations may apply to those blends. One-hundred percent
biodiesel contains no petroleum-based products or hazardous substances. Therefore, UST
regulations generally do not apply to 100 percent biodiesel. However, 100 percent biodiesel also
has material compatibility issues with storage and dispensing equipment. According to the
National Renewable Energy Laboratory's (NREL's) "Biodiesel Handling and Use Guide"
(NREL, 2009a), 100 percent biodiesel is not compatible with some hoses, gaskets, seals, metals,
and plastics. These compatibility issues are minimized at lower biodiesel blends; 20 percent
biodiesel (B20) and 5 percent biodiesel (B5) are commonly used blends that have not shown
significant material compatibility issues with engine or storage tank components. However, it is
important that the biodiesel fuels used in these blends meet fuel quality specifications, as
outlined in ASTM D6751, the standard specification for biodiesel fuel blend stock.
Biodiesel, like petroleum diesel, is not water soluble. However, when released to the
environment, biodiesel degrades approximately four times faster than petroleum diesel. In
aquatic environments, biodiesel degrades fairly extensively (Kimble, n.d.). Results of aquatic
toxicity testing of biodiesel indicate that it is less toxic than petroleum diesel (Kahn et al., 2007).
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Biodiesel does have a high oxygen demand in aquatic environments, and can cause fish kills as a
result of oxygen depletion (Kimble, n.d.). Water quality impacts associated with spills at
biodiesel facilities generally result from discharge of glycerin, rather than biodiesel itself
(Kimble, n.d.).
4.5. Biofuel End Use
Most vehicles on the road today can operate on low-level ethanol blends containing up to
10 percent ethanol (E10). Over 90 percent of U.S. gasoline is a low-level ethanol blend such as
E10 to boost octane for more complete combustion or to meet air quality requirements
(Alternative Fuels and Advanced Vehicles Data Center, 2010). E85 is another form in which
ethanol is consumed, but it can only be used in flex-fuel vehicles, which can run on any gasoline
ethanol blend up to 85 percent ethanol. Under current market circumstances, greater deployment
of flex-fuel vehicles may be needed to meet the Energy Independence and Security Act (EISA)
mandated volume standards.
Biodiesel is also commonly used as a blend with petroleum diesel. Because of biodiesel's
chemical properties, it is interchangeable with petroleum-based diesel fuel up to a 5 percent
blend, as long as it meets the ASTM D6751 biodiesel fuel specification. Biodiesel blends up to
20 percent are also commonly used in the United States, especially for fleet vehicles (NREL,
2009a).
Biodiesel can also be used in its pure form, known as "neat biodiesel" or B100, but most
vehicle and engine manufacturers do not recommend its use in non-approved engines and
vehicles. Previously, there were some concerns regarding maintenance issues related to engines
operated on biodiesel blends greater than 20 percent (B20), because the fuel has been shown to
soften and degrade certain types of elastomers and natural rubber compounds over time. This
will impair fuel system components such as fuel hoses and fuel pump seals. Such component
degradation can lead to leaks, poor performance, and other problems that are likely to result in
increased emissions and subsequent environmental impacts. This issue is limited to vehicles
from the early 1990s or earlier that used natural or nitrile rubber fuel system components; newer
vehicles use biodiesel-resistant fuel system components made of materials such as Teflon®,
Viton®, fluorinated plastics, and nylon. Compatibilities between B100 and specific materials
have been identified. In general, there are no material compatibility issues with B20 or blends
with lower biodiesel fraction, unless the fuel has been oxidized (NREL, 2009a).
Biofuels for jet aircraft require additional refining or need to be blended with typical jet
fuels to meet the standards of commercial aviation fuels. There are few long-term studies of
biofuel performance on large diesel engines such as stationary power generators, ships,
locomotives, and jet engines.
4.5.1. Air Quality
The primary impact associated with biofuel end use is air quality. Section 21 l(v) of the
Clean Air Act (CAA) requires EPA to study the air quality impacts associated with the use of
biofuel and biofuel blends. EPA has already adopted mobile source emission control programs
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
that reduce air pollution emissions and improve air quality. If necessary, EPA will issue further
regulations to mitigate adverse air quality impacts as a result of increases in biofuels.
4.5.1.1. Ethanol
The following discussion is based on E10, because considerably more information is
available about its use. A wide variation in evaporative and tailpipe emissions has been reported
due to a range of factors, such as the age of the vehicle, the power output and operating condition
of the engine, the fuel characteristics, how the vehicle is operated, and ambient temperatures
(Graham et al., 2008; Yanowitz and McCormick, 2009; Ginnebaugh et al., 2010). In 2010, a
partial waiver was granted by EPA under Section 21 l(f)(4) of the CAA that allowed the use of
E15 in certain vehicles. Specifically, this waiver allowed the use of E15 in model year 2007 and
new light-duty vehicles (i.e., cars, light-duty trucks, and medium-duty passenger vehicles) (U.S.
EPA, 2010f). It also denied the use of E15 in model year 2000 and older light-duty vehicles, as
well as all heavy-duty gasoline engines and vehicles, highway and off-highway motorcycles, and
non-road engines, vehicles, and equipment. Currently, an additional waiver is under
consideration by EPA for El5 use in other model year vehicles.
The emission impacts of the 2022 RFS2 volumes in the RFS2 RIA (U.S. EPA, 2010a)
were quantified relative to two reference cases: (1) the original RFS program (RFS1) mandate
volume of 7.5 billion gallons of renewable fuel (6.7 billion gallons ethanol) and (2) the U.S.
Department of Energy (DOE) Annual Energy Outlook (AEO) 2007 projected 2022 volume of
13.6 billion gallons of renewable fuels. In the RFS2 RIA, EPA projected decreases in emissions
of CO, benzene, and acrolein in 2022 under the RFS2-mandated volumes of biofuels, while NOX,
hydrocarbons (HC), and the other air toxics, especially ethanol and acetaldehyde, were projected
to increase. The inclusion of E85 emissions effects would be expected to yield larger reductions
in CO, benzene, and 1,3-butadiene, but more significant increases in ethanol, acetaldehyde, and
formaldehyde (U.S. EPA, 2010a).
4.5.1.2. Biodiesel
Air emissions from combustion of some biofuels, such as ethanol, are relatively
independent of feedstock or conversion process. However, biodiesel emissions may be highly
variable depending on the feedstock type (U.S. EPA, 2002; Lapuerta et al., 2008). With respect
to carbon content, plant-based biodiesel is slightly higher percentage-wise than animal-based
biodiesel in gallon-per-gallon comparisons. For NOX, PM, and CO, plant-based biodiesel tends to
have higher emissions than animal-based biodiesel for all percent blends (U.S. EPA, 2002).
Recent advances in diesel engine emission control technology have resulted in significantly
lower levels of air pollutant emissions.
Studies of biodiesel and biodiesel blends show varying results depending on the fuel (i.e.,
type of biodiesel, biodiesel blend, type of base diesel), the vehicle being tested, and the type of
testing. In general, combustion of biodiesel has been shown to decrease PM, CO, and HC
emissions, increase NOX emissions, and increase ozone-forming potential (Gaffney and Marley,
2009; U.S. EPA, 2002). However, it should be noted that petroleum-based diesel-fueled vehicles
are expected to emit significantly lower amounts of SO2 because of the Heavy-Duty Engine and
Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements (2007 Heavy-Duty
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Chapter 4: Biofuel Production, Transport, Storage, and End Use
Highway Rule) and the availability of low-sulfur diesel fuel in the marketplace, which must be
accounted for when considering the emission benefits of low SOX biodiesel (U.S. EPA, 2001).
Blending biodiesel in low percentages will not have much impact on sulfur emissions.
EPA's RFS2 RIA investigated the impacts of 20 percent by volume biodiesel fuels on
NOX, PM, HC, and CO emissions from heavy-duty diesel vehicles, compared to using 100
percent petroleum-based diesel. Average NOX emissions were found to increase 2.2 percent,
while PM, HC, and CO were found to decrease 15.6 percent, 13.8 percent, and 14.1 percent,
respectively, for all test cycles run on 20 percent by volume soybean-based biodiesel fuel.
Biodiesel results were included in the EPA analysis; however, the biodiesel contribution to
overall emissions is quite small (U.S. EPA, 2010a).
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Chapter 5: International Considerations
5. INTERNATIONAL CONSIDERATIONS
5.1. Introduction
In the global context, biofuel demands from an increasing number of countries will have
direct and indirect impacts, not only on countries that produce biofuels, but also on countries that
currently rely on imports of agricultural commodities from biofuel producers (Hertel et al.,
2010a, 2010b; Pimentel et al., 2009; Zah and Ruddy, 2009). Section 204 of the Energy
Independence and Security Act (EISA) calls for EPA to report to Congress on the environmental
impacts outside the United States caused by U.S. biofuel use. Therefore, this chapter focuses on
potential impacts in foreign countries from implementation of the revised Renewable Fuels
Standard program (RFS2) standards. Specifically, this chapter presents the current international
production and consumption of two biofuels (ethanol and biodiesel), discusses the composition
of future biofuel production, examines current and projected import and export volumes, and
discusses the environmental and other impacts of direct and indirect land use changes.
International trade is the primary mechanism through which U.S. biofuel policy will
affect foreign nations. Ethanol and, to a much smaller degree, biodiesel, have become global
commodities. Both are produced in many countries (Figure 5-1) and both are traded in
international markets. Primary producers of ethanol are Brazil, the United States, the European
Union, India, and China. Brazil is the only significant exporter of ethanol (See Table 5-1). Based
on computer modeling, changes in U.S. production and consumption volumes, such as those in
RFS2, are predicted to result in land allocation impacts that have global ramifications through
international trade and market price. As a crop price rises, land may be reallocated to grow more
of that crop in response to market price; conversely, as a crop price declines, land may tend to be
reallocated to grow less of that crop in response to market price. The extent of such conversions
will depend on many factors, such as local land use policies and incentives, knowledge of
alternatives, access to international markets, and cultural norms. There are differing opinions on
the result of possible tradeoffs between land uses and it is not possible at this time to predict with
any certainty what type of land use change will result from increased U.S. demand for biofuel
and what its environmental consequences will be (Fargione et al., 2008; Goldemberg et al., 2008;
Searchinger et al., 2008; Hertel et al., 2010b).
Resulting environmental impacts, both positive and negative, include effects from land
use change and impacts on air quality, water quality, and biodiversity. From a U.S. perspective,
the severity of these impacts will depend on the volume and location of future imports and
exports, both of biofuel and displaced agricultural goods.
In 2008, the United States and Brazil together produced 89 percent of the world's fuel
ethanol, with the United States producing around 9 billion gallons (see Table 5-1) (U.S. EIA,
n.d.[b]). In 2009, U.S. ethanol production increased to 10.9 billion gallons, and similar increases
occurred in most ethanol-producing nations as they attempted to increase the portion of biofuel
in their energy mix (U.S. EIA, n.d.[b]). Total world production has nearly doubled from 10.9
billion gallons in 2006 to 20.3 billion gallons in 2009. Figure 5-1 shows the geographical
distribution of biofuel production. Patterns of ethanol consumption generally matched those of
production, with the largest producers also being the largest consumers (U.S. EIA, n.d.[b]).
5-1
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Chapter 5: International Considerations
Biofuel production
Colombia
Sweden
Germany C
Denmark: Poland
France
China
.
Spain
Italy
Czech Republic
Slovakia
Austria
India
Sources: EarthTrends Environmental
Information Portal, World Resources Institute,
2007 (using WorldWatch 2006: US Department
of Energy, 2006): REN21. Renewables 2006
global status report, WorldWatch Institute; F. O.
Licht world ethanol & biofuels report 2005.
Thousand million litres
16,5
:. Ethanol
Biodiesel
Source: UNEP/GRID-Arendal, 2009.
Figure 5-1: International Production of Biofuels
Table 5-1: Top Fuel Ethanol-Producing Countries from 2005 to 2009
(All Figures Are in Millions of Gallons)
Country/Region
United States
Brazil
European Union
China
Canada
Jamaica
Thailand
India
Colombia
Australia
Other
Total world
production
2005
3,904
4,237
216
317
67
34
18
57
8
6
93
8,957
2006
4,884
4,693
427
369
67
80
34
63
71
20
216
10,924
2007
6,521
5,959
477
440
212
74
46
69
72
21
276
14,167
2008
9,283
7,148
723
526
250
98
87
71
67
38
393
18,684
2009
10,938
6,896
951
567
287
106
106
89
80
54
274
20,348
Source: U.S. EIA, n.d.[b].
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Chapter 5: International Considerations
On the other hand, the market—and thus the global production—for biodiesel is
concentrated in Europe, which represented about 60 percent of world production as of 2009
(U.S. EIA, n.d.[a]). The other 40 percent of global production is largely made up by the United
States, Brazil, Argentina, and Thailand, with U.S. production estimated at 505 million gallons for
2009, or about 10 percent of world biodiesel production (U.S. EIA, n.d.[a]). World biodiesel
production has been rapidly increasing over the past decade, from 242 million gallons in 2000 to
about 4.7 billion gallons in 2009 (U.S. EIA, n.d.[a]). These production increases have been
driven by increased consumption targets. For example, Brazil has planned to increase its
biodiesel blend from 5 to 10 percent by 2015.
5.2. Import/Export Volumes
U.S. biofuel import volumes will depend largely on the relative costs of U.S. biofuel
production and imported ethanol. These costs will be determined by domestic production
capacity, including the efficiency of the domestic ethanol-producing sector, and the yields
attained.
With respect to production capacity, as discussed in Chapter 2, the renewable fuel
volume mandates under EISA require that U.S. biofuel consumption steadily increase to 36
billion gallons by 2022. This biofuel will be composed of both conventional and advanced
biofuel (including cellulosic ethanol, algal biodiesel, and other forms of advanced biofuel). Most
of the 10.9 billion gallons of conventional ethanol that the United States produced in 2009 came
from corn starch. By 2015, the 10.9 billion gallons is expected to increase to the targeted volume
of 15 billion gallons provided for in the RFS2 program (as required under EISA) (GAO, 2007;
U.S. EPA, 2010a). Future production volumes of advanced biofuel that have not yet been
commercially developed are uncertain. In its RFS2 Regulatory Impact Analysis (RIA), EPA
estimated that cellulosic technologies could combine to provide an additional 16 billion gallons
of ethanol by 2022, with a substantial portion of this, 7.8 billion gallons worth, using corn stover
as a cellulosic feedstock source (U.S. EPA, 2010a). In addition, some estimates place U.S.
biodiesel production at roughly 1.3 billion gallons by 2019 (FAPRI, 201 Ob). In 2022, the RFS2
RIA projects that the remaining 4 billion gallons needed to meet the EISA mandate would be
composed of a combination of imported sugarcane ethanol from Brazil as well as "other
advanced biofuel" (U.S. EPA, 2010a). Figure 5-2 shows the projected import volumes forecasted
in the RIA for each year from 2011 to 2022.
Figure 5-2 shows that import volumes are expected to be very low in years preceding
2015, followed by a significant increase in import volumes between 2015 and 2022. This is in
part because domestic corn starch ethanol production is expected to increase until it reaches the
2015 peak under RFS2. The total renewable fuel targets may not be reached with domestic
production until 2018 or beyond (see Table 2-1). It should also be noted that 2010 import figures
have been much lower than those expected when forecasts were made in 2009. Imports of fuel
ethanol for the first three-quarters of 2010 have totaled 17 million gallons (USDA, n.d.)—well
below EPA's 200 million gallons forecast (U.S. EPA, 2010a). U.S. biofuel imports and exports
will also be influenced by trade policy, including tariffs and other incentives in the United States
and other countries. Even if the United States succeeds in meeting the RFS2 targets, the United
States likely will continue to import and export biofuel as individual producers take advantage of
international price differences. Over the past decade (2002 to 2009), U.S. ethanol import
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Chapter 5: International Considerations
quantities varied (see Figure 5-2), mostly due to volatility in the prices of related commodities
such as corn, sugar, and other feedstocks, as well as prices of energy commodities such as oil.
16
^ Projected
14 ^
* U.5. Production
12 '*
10
Projected Imports
2002 2004 2006 2008 2010 2012 2014 2016 2018 2020 2022
Sources: For 2000 to 2009 production data, U.S. EIA, n.d.[b]. For 2000 to 2009 import data, U.S. EIA, n.d.[c].
For 2011 to 2022 production and import projections, U.S. EPA, 2010a.
Figure 5-2: Annual U.S. Domestic Ethanol Production and Imports Volumes Reported
(2002 to 2009) and Projected (2011 to 2022)
The bulk of U.S. ethanol imports are sugarcane-based ethanol from Brazil. In 2008, the
United States was the largest importer of Brazilian ethanol, followed by the Netherlands and a
number of Caribbean countries (see Table 5-2). However, foreign-produced ethanol is also
imported to the United States via these Caribbean countries where the Caribbean Basin Initiative
(CBI), a regional trade agreement, enables up to 7 percent of the biofuel consumed in the United
States to be imported duty-free from CBI member countries (Yacobucci, 2005; Farinelli et al.,
2009). Therefore, most of the Brazilian exports shown as going to CBI member countries such as
Costa Rica, Jamaica, El Salvador, and Trinidad and Tobago (see Table 5-2) is eventually re-
exported to the United States (U.S. EIA, n.d., [c]). Looking closer at the Brazilian export figures
in Table 5-2, it is evident that ethanol trade changed somewhat dramatically in 2009, with most
destinations experiencing a significant decline in imports. A large part of this decline was due to
the drop in U.S. imports caused by a change in energy prices, as well as an increase in sugar
prices that made imported Brazilian ethanol less competitive in the U.S. market (Lee and
Sumner, 2010). These rising sugar prices, as well as the recent strengthening of Brazil's
currency, could significantly hinder Brazil's ability to supply the U.S. market moving forward.
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Chapter 5: International Considerations
While there is currently a tariff in place through December 2011, these factors may limit future
imports even were the tariff to expire (USD A, 2010d).
Table 5-2: 2008-2009 Brazilian Ethanol Exports by Country of Destination
Destination Country
Total
United States
Netherlands
Jamaica
El Salvador
Japan
Trinidad and Tobago
Virgin Islands (U.S.)
Republic of Korea (South Korea)
Costa Rica
Nigeria
United Kingdom
Volume (Million Gallons)
2008
1,352.9
401.6
351.9
115.3
94.1
69.6
59.3
49.7
49.3
28.9
25.9
18.4
% of Total
100%
29.7%
26.0%
8.5%
7.0%
5.1%
4.4%
3.7%
3.6%
2.1%
1.9%
1.4%
2009
870.8
71.9
179.2
115.6
18.8
74.0
37.0
3.4
82.9
26.5
30.6
42.7
% of Total
100%
8.3%
20.6%
13.3%
2.2%
8.4%
4.2%
0.4%
9.5%
3.0%
3.5%
4.9%
Source: SECEX, n.d.
Note: Percentages do not sum to 100 percent because some destinations are not listed. Original data were
converted from liters to gallons.
The United States also exports biofuel (including ethanol and biodiesel) to foreign
countries. Canada has been the primary recipient of U.S. exports, with Europe becoming a more
prevalent destination beginning in 2004 (see Figure 5-3) as its biofuel consumption has
increased. U.S. ethanol exports have increased in recent years due to increased production.
However, export levels, ranging from about 50 million to 175 million gallons, are no more than 1
percent of domestic production and are far outweighed by imports. Exports are likely to continue
to lag behind imports in the near term as consumption rises.
Table 5-3 shows the 2008 U.S. biodiesel trade balance. In 2008, 46.8 percent of
domestically produced biodiesel was exported. Biodiesel export volume has increased
dramatically in recent years, from about 9 million gallons in 2005 to nearly 677 million gallons
in 2008 (U.S. EIA, n.d.[a]). In 2009, biodiesel export volume fell dramatically to only 266
million gallons (USDA, n.d.). Current projections have net U.S. biodiesel exports (i.e., exports
minus imports) falling for the next few years and then rising back up to around 100 million
gallons by the end of the decade (FAPRI, 201 Ob).
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Chapter 5: International Considerations
• Other
Mexico
• Australia
• European Union
• United Arab Emirates
• Canada
2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09
Market Year
Source: ERS, 2010a.
Note: Original data were converted from liters to gallons.
Figure 5-3: Historic U.S. Ethanol Export Volumes and Destinations
Table 5-3: 2008 U.S. Biodiesel Balance of Trade
Item
U.S. production
U.S. consumption
Production - consumption =
U.S. imports
U.S. exports
Exports - imports =
Quantity
774 million gallons
412 million gallons
362 million gallons
315 million gallons
677 million gallons
362 million gallons
5.3.
Source: U.S. EIA, 2009, n.d.[b].
Environmental Impacts of Direct and Indirect Land Use Changes
EISA requires that "direct emissions and significant indirect emissions such as significant
emissions from land use change" be considered as part of the analysis of environmental impacts
stemming from domestic biofuel production and consumption. The issue of land use change
inherently includes international considerations, because the demand for biofuel in the United
States can influence the international availability of crops such as corn and soybeans for both
biofuel and agricultural markets, which in turn can incentivize land use changes in other
countries to meet that demand. Land use changes are considered either direct or indirect. In the
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Chapter 5: International Considerations
context of biofuels, direct land use change refers to land conversion that is directly related to the
biofuel supply chain. An example of direct land use change would be the planting of biofuel
feedstock on land, which was previously native forest, to increase the supply of ethanol to export
to the United States. Indirect land use change refers to land conversion that is a market-oriented
response to changes in the supply and demand of goods that arise from increased production of
biofuel feedstocks. An example of indirect land use change would be the clearing of foreign land
to plant corn in response to an increase in global commodity prices caused by a decrease in U.S.
corn exports. Some have argued that these indirect impacts should not be counted as part of the
biofuel carbon footprint because they are too difficult to relate back to biofuel production and
because of the disparity of highly variable responses based on local policies and conditions. It is
instructive, however, to consider the potential impacts if they were to be realized, and this has
been done routinely through the use of economic modeling.
In the RFS2 RIA, EPA estimated greenhouse gas (GHG) impacts of direct and indirect
land use change using the FAPRI-CARD model.25 This model predicts world prices by equating
excess supply and demand across countries. Changes in world prices determine changes in
worldwide commodity production and trade. Under this model, two primary domestic effects
directly affect a commodity's worldwide use and trade: changes in U.S. exports and changes in
domestic U.S. prices (U.S. EPA, 2010a). Using this model, the RFS2 RIA analysis compares
2022 crop area and production (by crop type and country) predicted to result with and without
(i.e., "business as usual") EISA requirements. The results of this analysis are shown in Figures
5-4 through 5-7 and in Table 5-4. In Figures 5-4 through 5-7, each column shows the marginal
impact of a scenario that focuses on that particular feedstock in isolation.
The RFS2 RIA forecasts that, by 2022, for every increase of 1,000 gallons of corn starch
ethanol production in the United States, corn exports will have decreased by 4 tons. Similarly,
for every increase of 1,000 gallons of soybean-based biodiesel produced domestically, soybean
oil exports will have decreased by just over 2 tons (see Figure 5-4) (U.S. EPA, 2010a). Thus, as
the United States increases domestic production of corn starch ethanol and soybean diesel,
exports of corn and soybean for agricultural or other uses are expected to decline, which might
result in indirect land use change in the form of land conversion to agriculture in other countries.
This result is consistent with the results of a 2009 study, which predicted that due to production
increases required by EISA, U.S. coarse grain exports will decrease to all destinations and this
could cause dominant export competitors and trading partners, likely in Latin America, China,
and the Pacific Rim, to convert more of their lands to make up the difference (Hertel et al.,
2010a; Keeney and Hertel, 2009). However, given that RFS2 limits the amount of corn starch
ethanol that can be counted toward the mandated volume targets at 15 billion gallons—a level
the United States is expected to reach by 2015 or sooner (GAO, 2007; U.S. EPA, 2010a)—
indirect land use change impacts resulting from changing trade patterns of corn and other grains
may level off at that point. Assuming agricultural yield improvements continue and cellulosic or
other production technologies develop to commercialization and replace conventional ethanol
production, U.S. biofuel consumption could decrease pressure on conversion of land to
agricultural use internationally.
25 FAPRI-CARD is a worldwide agricultural sector economic model. For the RIA, the model was run by the Center
for Agricultural and Rural Development at Iowa State University on behalf of EPA.
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Chapter 5: International Considerations
1.0
-5.0
Corn Ethanol
Soy Biodiesel
Sw ifchgrass Bhanol
Imported Bhanol
Source: U.S. EPA, 2010a.
Figure 5-4: Change in U.S. Exports by Crop Anticipated to Result from EISA
Requirements by 2022
The RFS2 RIA also estimates that the additional biofuel produced to meet the EISA
mandates (2.7 billion gallons of corn starch ethanol, 0.5 billion gallons of soy-based biodiesel,
1.6 billion gallons of sugarcane ethanol, and 7.9 billion gallons of switchgrass cellulosic ethanol)
compared to "business as usual," will lead to the creation of additional international cropland
(approximately 2 million acres of corn, 3.4 million acres of soybeans, 1.1 million acres of
sugarcane, and 1.7 million acres of switchgrass) (see Table 5-4) to supply U.S. biofuel imports
and respond to the U.S. reductions in exports shown in Figure 5-4 (U.S. EPA, 2010a).
Table 5-4: Increases in International Crop Area Harvested by Renewable Fuel Anticipated
to Result from EISA Requirements by 2022
Feedstock's Marginal Effect
Considered
Corn starch ethanol
Soy-based biodiesel
Sugarcane ethanol
Switchgrass ethanol
International Crop Area Increase
(Thousands of Acres)
1,950
1,675
1,063
3,356
Normalized Crop Area Increase
(Acres per Billion BTU)
9.74
26.32
10.82
5.56
Source: U.S. EPA, 2010a.
Note: Figures converted from hectares to acres. Crop area changes were normalized by dividing by the incremental
increase in renewable fuel production in a given scenario and year, on an energy-content basis.
Further, according to the EPA analysis, assuming few or weak local controls that reduce
ability or incentive for land conversion, these direct and indirect land use changes will lead to
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Chapter 5: International Considerations
significant GHG emissions (before accounting for GHG savings resulting from petroleum
displaced as the biofuel is consumed). Figure 5-5 shows that, based on the model presented in the
RFS2 RIA, soy-based biodiesel causes the largest release of GHG emissions (measured in
kgCO2e/mmBTU) resulting from international land use change. The RFS2 RIA model results
indicate that the majority of emissions resulting from international land use change originate in
Brazil in the scenarios for corn ethanol and switchgrass ethanol. This is largely a consequence of
projected pasture expansion in Brazil, and especially in the Amazon region where land clearing
causes substantial GHG emissions. Of the renewable fuels analyzed, the analysis found that
sugarcane ethanol causes the least amount of emissions resulting from land use change. This is
due largely to the EPA projection that sugarcane crops would expand onto grasslands in south
and southeast Brazil, which results in a net sequestration because sugarcane sequesters more
biomass carbon than the grasslands it would replace. Recent data indicate that deforestation rates
in Brazil are declining (INPE, n.d.). Given that the largest component of life cycle GHG
emissions for corn starch ethanol in the RFS2 RIA results from indirect land use change in Brazil
(U.S. EPA, 2010a), understanding the drivers and trends in Brazilian deforestation is important.
Various factors influence deforestation rates, including investments in enforcement and
monitoring, expanding protected areas, improving land titles for small and medium sized land
holders, commitments from agricultural industries, and the establishment of government
programs. Changes in land use are being followed closely and more recent analyses may change
the outlooks reported here.
m
E
E
• Soy Biodiesel
• Corn Ethanol
Sugarcane Ethanol
• Switchgrass Ethanol
Brazil
Rest of World
World
Source: U.S. EPA, 2010a.
Figure 5-5: International Land Use Change GHG Emissions Projected to Result from EISA
Requirements by 2022
The GHG emissions shown in Figure 5-5 can be seen as an international "carbon debt"
(Fargione et al., 2008). Clearing forested areas or pasture land for new cropland results in
enhanced microbial decomposition of organic carbon and elevated GHG emissions. As described
in the RFS2 RIA, the location of land use change is a critical factor determining the GHG
impacts of land use change, because these impacts will vary substantially by region (U.S. EPA,
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Chapter 5: International Considerations
2010a). The conversion of higher carbon-storing types of land such as tropical rainforest will
lead to more carbon emissions (U.S. EPA, 2010a).
As noted previously, the results of modeling projected impacts are diverse and it is not
possible at this time to predict with any certainty what type of land use change in other countries
will result from increased U.S. demand for biofuel or what its environmental consequences will
be. (Compare, for example, Fargione et al., 2008; Goldemberg et al., 2008; Hertel et al., 2010b;
and Searchinger et al., 2008.) However, if natural ecosystems are converted to cropland, it may
take many years for biofuel consumption to "pay down" the carbon debt created from production
with GHG savings compared to displaced petroleum. On the other hand, biofuel made from more
sustainable grasses or woody crops using higher-yield cellulosic technologies, or from waste
biomass or biomass grown on degraded and abandoned agricultural lands, results in much
smaller carbon debts and is more likely to lead to overall GHG reductions (Fargione et al., 2008).
Figure 5-6 shows forecasted crop area changes by region, with the heaviest impacts occurring in
Brazil. It should be noted that the FAPRI-CARD model does not predict what type of cropland
will emerge in foreign countries if land use change does occur. This is an important source of
uncertainty and GHG and other environmental impacts could vary significantly depending on
what crops are grown to offset decreasing U.S. agricultural exports.
• SoyBiodiesel
• CornEthanot
Sugarcane Ethanol
iSwitchgrass
Ethanol
Africa & Asia Oceania Brazil Canada Eastern India Other Rest of United Western World
Middle Europe & Latin World States Europe
East Russia America
Source: U.S. EPA, 2010a.
Figure 5-6: Harvested Crop Area Changes Projected to Result from EISA Requirements
by 2022
Brazil could continue to be a supplier of U.S. ethanol and will have an important role in
international trade of coarse grains and soybeans, so it is informative to consider potential land
use changes there. Brazil faces challenges of multiple forms of land use change, both direct and
indirect. Land use changes could occur if Brazil increases ethanol production by converting more
land from growing other agricultural goods, or from use as pasture land, to grow sugarcane. As
pasture lands are converted to sugarcane production, ranchers are pressured to "intensify"
livestock production or clear more land (possibly Amazon rainforest or Cerrado woodland)
(Bustamante et al., 2009). Figures 5-5 and 5-7 isolate the impacts on Brazil alone. The model
results presented in Figure 5-7 appear to be consistent with the prediction that pasture land will
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Chapter 5: International Considerations
decrease in Brazil, while increasing in the rest of the world. However, it is unclear if this would
result in rainforest loss or simply mean a greater number of livestock animals per acre. Recent
monitoring of the rain forests indicates that deforestation rates in Brazil are declining (INPE,
n.d.).
i
-10
I Corn Ethanol
I Soy Biodiesel
Sugarcane Ethanol
I Switchgrass Ethanol
Amazon Central- Northeast North- South Southeast Brazil
Biome West Coast Northeast
Cerrados Cerrados
Source: U.S. EPA, 2010a.
Figure 5-7: Modeling of Pasture Area Changes in Brazil Anticipated to Result from EISA
Requirements by 2022
5.4. Other Environmental Impacts
While production of biofuel feedstocks places only one of many demands on water,
fertilizer, and other inputs, its impacts will increase as its production increases. Studies have
shown that water tables are already declining in the western United States, North India, Pakistan,
North China, Mexico, and the Mediterranean (Shah et al., 2007). These trends indicate the
vulnerability of various regions to water scarcity issues. The choice of feedstock, cultivation
practices, and the location of cultivation will greatly influence how production of biofuel impacts
water availability.
Water quality and flooding issues are also relevant. As described in Chapter 3, U.S. corn
production has been a key driver of hypoxia in the Gulf of Mexico. Similar water quality issues
could arise or be exacerbated in other countries if feedstock production increases and appropriate
management practices are not used. Conversion of land to biofuels feedstock production could
have varying impacts, depending on prior ecological function of the converted land and the types
of management practices employed. Impacts could include encroachment on wetlands and the
discharge of excess nutrients to water resources. For example, Brazilian surface waters suffered
from hypoxia during the early stages of their biofuel development when the vinasse, a byproduct
of the sugarcane-ethanol production process rich in nitrogen and potassium, was routinely
discarded into rivers, lakes, and reservoirs, causing extensive eutrophication (Simpson et al.,
2009). Brazilian federal law has prohibited the dumping of vinasse into any water body since
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Chapter 5: International Considerations
1978. The effluent is now returned to the field as fertilizer, and water quality has improved
significantly. However, if other developing countries opt to produce biofuel and do not properly
regulate water quality impacts, eutrophication could damage these nations' aquatic ecosystems.
Also, if biofuel-related land use change does occur and if it results in deforestation and loss of
wetlands, then increased flooding, sedimentation, and lower stream base flows are also likely to
occur.
Biofuel production also affects international air quality. While the displacement of
petroleum fuels by biofuels does have a positive impact, the air quality issues associated with
biofuel feedstock harvesting, refining, and transport could erode these savings if poor
management practices are allowed to occur. For instance, the practice of burning sugarcane
fields prior to harvesting is a serious air pollution issue in Brazil. It has resulted in large aerosol
and trace gas emissions, significant effects on the composition and acidity of rainwater over
large areas of southern regions, and elevated ozone levels in those areas affected by the burning.
However, harvest burning practices are being phased out in Brazil through state regulations. In
2007, state laws ensured that 40 percent of the sugarcane was harvested without burning in the
state of Sao Paulo, and this is forecast to reach 50 percent by 2010 and about 90 percent by 2022
(Goldemberg et al., 2008; U.S. EPA, 2010a). Like many of the effects discussed so far, the
severity of air emissions will be highly sensitive to local policies which influence the feedstock
selected, location of production, and management practices.
Finally, if increased biofuel consumption in the United States does lead to indirect land
use changes and more natural habitat is cleared to create agricultural lands, a loss of biodiversity
will occur. Many biofuel production regions coincide with areas with high biodiversity value.
For example, many ecosystems in Brazil support high levels of biodiversity. Depending on
where biofuel feedstock production occurs, and the manner in which it occurs, impacts on
biodiversity could be significant.
5.5. Conclusions about International Impacts
Simulations prepared for the RFS2 indicate that the EISA biofuel targets could alter U.S.
and international trade patterns and commodity prices (U.S. EPA, 2010a). The manner in which
countries respond to U.S. market conditions, including influences from deforestation, could
affect net GHG savings derived from biofuels. As with biofuel production in the United States,
these impacts will depend largely on where the crops are grown, forest and agricultural
management practices and technologies used, and the efficacy of environmental policies. Global
mitigation strategies will have to consider the international implications of biofuel production.
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Chapter 6: Synthesis, Conclusions, and Recommendations
6. SYNTHESIS, CONCLUSIONS, AND RECOMMENDATIONS
6.1. Introduction
This chapter presents a qualitative synthesis, major conclusions, and recommendations
derived from information assessed in this report. This synthesis is based upon a consensus view
of the authors of this report given the broad range of assumptions found in the scientific
literature. The synthesis and conclusions illustrate an assessment of the environmental impacts
attributable to activities in the biofuels supply chain, from feedstock production to biofuel
production, transport and storage. End use impacts and international considerations are also
synthesized. The synthesis discusses the range, magnitude, and uncertainty of environmental
impacts from the six feedstocks (corn starch, soybean, corn stover, perennial grasses, woody
biomass and algae) and three fuels examined (corn ethanol, soybean biodiesel and cellulosic
ethanol). This constitutes a set of initial expectations based on available literature through July
2010—it should not be construed as a definitive prediction. Salient points are derived from
Chapters 3, 4, and 5 across feedstocks and fuels, domestically and internationally, organized by
environmental impact category. Finally, the recommendations comprise a set of suggestions
concerning environmental assessment, research coordination, impact mitigation, and sustainable
biofuels practices. Each of these recommendations will advance approaches for the next Report
to Congress, and hopefully promote favorable environmental outcomes as biofuel usage expands
in the United States.
6.2. Assessment Scenarios
The published peer-reviewed literature reviewed for this report shows that the production
of biofuels can result in a wide range of environmental impacts, including both negative and
positive impacts. This range of impacts depends largely on land use changes, management
approaches, and regional characteristics such as climate, soil, and ecological factors. In order to
effectively synthesize the literature, the authors developed assessment scenarios that represent
the range of impacts, as revealed from the literature. The construct of these scenarios is
presented below.
6.2.1. Assumptions Underlying the Synthesis of Feedstock Production Impacts
Domestic environmental impacts associated with feedstock production depend upon the
conditions under which they are grown. The authors examined available peer-reviewed
information to identify reasonable conditions under which a "most negative" and "most positive"
environmental impact could arise for each feedstock and impact category. Land-use changes
considered were restricted to those allowable under the RFS2 program (U.S. EPA, 2010a). Other
conditions considered included: management approaches, regional characteristics, and
technologies. For example, it was determined from the literature that the most negative water
quality impact from producing corn starch as a feedstock would likely arise if corn grown with
conventional tillage and high chemical inputs replaced uncultivated land such as that in the
Conservation Reserve Program (CRP). Conversely, the most positive water quality impact from
producing corn starch would arise if corn grain was merely diverted from other uses with no
increase in corn acreage; utilizing land already in corn production would likely result in a
"negligible effect," because sedimentation and nutrient contamination would remain at near
6-1
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Chapter 6: Synthesis, Conclusions, and Recommendations
current levels. This approach was repeated for each feedstock and impact category and the
results are highlighted in associated tables (Tables 6-1, 6-2).
The authors also considered the impacts of the "most plausible" conditions under which a
feedstock might be produced. The term "plausible" is used rather than "probable" to make clear
that these are not probabilistic predictions. The state of science and advances in technology in
this rapidly growing field do not permit a quantitative determination of the likelihood of future
practices at this time. "Most plausible" impacts are based on sets of assumptions commonly
considered in the literature and include type of land converted, management approaches, regional
influences, and technologies, as shown in the last column of Table 6-1.
Because corn and soybeans are both currently used in commercial production of biofuels,
the impacts depicted can be thought of as plausible now and in the future. On the other hand,
impacts attributable to the remaining feedstocks are plausible in the future only since they are not
yet in full-scale commercial use.
6.2.2. Assumptions Underlying the Synthesis of Biofuel Production, Transport, and Storage
Impacts
In evaluating the potential range of domestic environmental impacts associated with the
production, transport, and storage of each of three biofuels, the same iterative process described
above was used to determine "most negative" and "most positive". One notable difference is that
previous land use is not as essential to this determination. For example, an examination of the
literature found that the "most negative" water quality impact from producing corn grain ethanol
occurred when biofuel refinery effluent had high biological oxygen demand (BOD); dried
distillers grain (DDG) byproduct was fed to livestock with inadequate waste management
practices; and the fuel was stored in leaking underground storage tanks (USTs).
Table 6-2 lists key assumptions involving mostly production and storage practices and
technologies (because transportation will be similar, though not identical) found in the literature
that produce the "most plausible" impacts. Because corn grain ethanol and soybean biodiesel are
commercially produced, the impacts depicted can be thought of as plausible now and in the
future. On the other hand, impacts attributable to cellulosic ethanol are plausible in the future
only since it is not yet in full-scale commercial use. Sets of assumptions underlying the most
plausible impacts do not necessarily represent future practices, since technology is rapidly
changing.
6.3. Synthesis
EISA Section 204 calls for EPA to report to Congress every three years on the
environmental and resource conservation impacts of increased biofuel production and use,
including air and water quality, soil quality and conservation, water availability, ecosystem
health and biodiversity, invasive species, and international impacts. EPA interpreted the
requirements of Section 204 to be those environmental impacts beyond the reductions in
greenhouse gas emissions associated with the RFS program and recently analyzed in EPA's
RFS2 Regulatory Impact Analysis (U.S. EPA, 2010a). Using the peer-reviewed published
6-2
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Chapter 6: Synthesis, Conclusions, and Recommendations
Table 6-1: Assumptions Underlying the Synthesis of Feedstock Production Impacts
Environmental Impact Per Unit Area
Most negative
Negligible
Most positive
Most plausible
-C
u
k.
re
55
c
3
Soybean
k.
g
o
4-1
in
c
O
u
Perennial Grasses
Woody Biomass
cu
re
M
<
Corn grown with conventional
tillage, irrigation, and high
chemical inputs replaces
uncultivated land such as that
in the Conservation Reserve
Program (CRP).
Soy grown with conventional
tillage, irrigation, and high
chemical inputs replaces
uncultivated land such as that
in the CRP.
High rate of stover removal on
highly erodible land requiring
additional equipment passes
after corn grain harvesting
replaces same with no stover
removal.
Invasive perennial grasses
established with conventional
tillage and grown with a short
planting interval, high rates of
chemical inputs, and irrigation
replace uncultivated land such
as that in the CRP.
Invasive short-rotation woody
crops (SRWC) with short
replanting intervals, high
chemical inputs, high isoprene
emissions, and no coppicing
replace mature, managed,
low-isoprene-emitting tree
plantations.
Invasive species of algae grown
in open raceway ponds in drier
regions with freshwater and
high chemical inputs that are
not recycled.
Existing corn grown
with conservation
practices diverted to
biofuel supply chain.
No change in land use.
Existing soy grown
with conservation
tillage diverted to
biofuel supply chain.
No change in land use.
Existing corn grown with
conservation practices
diverted to biofuel supply
chain. No change in land use.
t Exception for water quantity
Soy grown with
comprehensive conservation
practices replaces corn grown
with conventional tillage and
high chemical inputs.
Existing corn with appropriate rate of stover removal to
minimize erosion, soil organic matter loss, and fertilizer
application given site-specific characteristics replaces
same with no stover removal. Single pass harvest with
corn.
Perennial grasses from
currently mowed
pasture or other
managed grasslands
diverted to biofuel
supply chain. No
change in land use.
Removal of managed
forest harvest residues
at rates that maintain
soil organic matter
and minimize erosion
replaces residues left
on site.
Non-invasive algae
grown with water
where it is abundant,
in closed bioreactors;
treated effluent is
recycled for further
use.
Non-invasive perennial grasses
established with no till and
grown with a long replanting
interval, low chemical inputs
and no irrigation replace
irrigated corn grown with
conventional tillage and high
chemical inputs.
Non-invasive, coppiced SRWC
with long replanting intervals,
low chemical inputs, and low
isoprene emissions replace
non-coppiced, managed
forests with short replanting
intervals and high isoprene
emissions. OR Low to
moderate rates of forest
residue removal orthinning
replaces residues left on site.
Non-invasive algae grown with
wastewater in closed
bioreactors; treated effluent is
recycled forfurther use.
Conventionally managed, tilled corn in
regions not requiring irrigation replaces
conventionally managed, no-till soy or other
row crops. Overall trend as reported by
USDA is increasing acreage of corn planted
since 2005 (see section 3.2.3).
Existing soy grown with conservation tillage
diverted to biofuel supply chain to meet
relatively small volumetric RFS2 biodiesel
requirements. Overall trend as reported by
USDA is relatively stable acreage of soybeans
planted since 2005 (excluding 2007, see
section 3.2.3).
Stover removal at "logistically removable"
rate (see USDA's Billion Ton Study), without
considering local characteristics, from
conventionally managed, tilled corn in
regions not requiring irrigation replaces
same with no stover removal. Impacts shown
are beyond corn cultivation and from
separate pass harvest.
Switchgrass grown with fertilizer in regions
not requiring irrigation replaces CRP and
other low management lands. Switchgrass
(unlike Giant Miscanthus) cultivated for
farm-scale studies on CRP in many areas of
US (see section 3.3.3).
Removal rate of managed forest harvest
residues without considering local
characteristics replaces residues left on site.
This is the greatest source of woody biomass
assumed underthe RFS2 RIA (EPA 2010b).
Algae grown in open ponds on marginal land
using nutrient-rich wastewater (see section
3.5.3).
*Sets of assumptions commonly used in the literature.
^Corn replaces CRP with relatively high annual evaporation in non-irrigated areas.
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Chapter 6: Synthesis, Conclusions, and Recommendations
literature, this report reviews impacts and mitigation strategies across the entire biofuel supply
chain, including feedstock production and logistics, and biofuel production, distribution, and use.
This literature demonstrates that production of biofuel feedstocks can result in a wide range of
environmental impacts, including negative and positive potential impacts. This range of
feedstock impacts depends largely on land use changes, management approaches and regional
climate, soil and other ecological characteristics.
Table 6-2: Assumptions Underlying the Synthesis of Biofuel Production, Transport and
Storage Impacts
Biofuel
Corn
Ethanol
Soybean
Biodiesel
Cellulosic
Ethanol
Environmental Impact Per Unit Volume
Most negative Negligible Most positive
Coal powered facility using
3-6 gallons of water per
gallon of ethanol; effluent
with high biological oxygen
demand (BOD); dried
distillers grain (DDG)
byproduct fed to livestock
with inadequate waste
management practices;
leaking underground
storage tanks (USTs).
Coal powered facility using
<1 gallon of water per gallon
of biodiesel; effluent with
high BOD, total suspended
solids (TSS) and glycerin
content; USTs leak.
Coal powered facility using
10 gallons of water per
gallon of ethanol; effluent
with high BOD; USTs leak.
Given current
knowledge, unlikely
that corn ethanol
facilities will have
negligible
environmental
impacts.
Given current
knowledge, biodiesel
facilities may approach
negligible
environmental impacts
on water quantity, but
not for other impact
categories.
Given current
knowledge, unlikely
that cellulosic ethanol
facilities will have
negligible
environmental
impacts.
Natural gas powered facility with
combined heat and power (CHP)
using <3 gallons of water per
gallon of ethanol by improving
water use efficiency and recycling;
effluent effectively treated for
BOD; DDG-fed livestock waste
used within comprehensive
nutrient management plan; USTs
do not leak.
Natural gas power facility with
CHP using <1 gallon of water per
gallon of biodiesel; effluent
effectively treated for BOD, TSS
and glycerin; USTs do not leak.
Natural gas powered or biomass
with CHP using <10 gallons per
gallon of ethanol by improving
water use efficiency and recycling;
effluent treated for BOD; USTs do
not leak.
Most plausible*
Facility uses ~3 gallons of
water per gallon of ethanol,
utilizes natural gas for heat,
produces DDG byproducts
fed to livestock with current
waste management
techniques. Spills and
storage tank leaks at
currently observed rates
Facility produces effluent
with current range of
pollutants (e.g., glycerin,
high BOD), uses <1 gallon of
water per gallon of
biodiesel, and utilizes
natural gas for heat. Spills
and storage tank leaks at
currently observed rates.
Facility uses >B gallons of
water per gallon of ethanol
and utilizes natural gas for
heat. Spills and storage tank
leaks at same rate as corn
ethanol.
*Sets of assumptions commonly used in the literature.
6.3.1. Feedstock Production
Synthesis of the feedstock production phase of the biofuel supply chain. Figure 6-1
provides a qualitative synthesis, based on the scientific literature, of the environmental impacts
of producing corn, soybeans, corn stover, perennial grasses, woody biomass, and algae. This
synthesis is meant to summarize, not substitute, the information contained in this document,
providing an illustration of the potential range and the most plausible environmental impacts
along the biofuel supply chain. It is based on EPA's review of the scientific literature through
July 2010 using a consensus of the authors to assign relative, qualitative values across
feedstocks, biofuels, and impact categories.
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Chapter 6: Synthesis, Conclusions, and Recommendations
The impacts presented in Figure 6-1 are on a per unit area basis, rather than another basis
of comparison (e.g., per gallon of biofuel) for five reasons: (1) environmental impacts are the
focus of this report and are most naturally described on a per unit area basis; (2) the dominant
driver of environmental impacts of feedstock production appears to be real changes in land use;
(3) a per unit area basis provides a foundation for mapping region-specific impacts; (4)
commonly used comparators (e.g., per unit energy) are insufficient for some impacts; and (5)
uncertainties in future commercial production were considered too large to develop an alternate
consistent unit of comparison. Impacts shown in this figure are relevant for only a unit area of
those regions where each feedstock is likely to be grown (see Chapter 3).
Limitations. No attempt has been made to compare impacts to those of petroleum
production, nor do impacts represent possible environmental benefits gained by petroleum
displacement. Comparison of petroleum and biofuels with respect to GHGs is presented in the
RFS2 Regulatory Impact Analysis (RIA) (U.S. EPA, 2010a); research comparing petroleum and
biofuels in all other impact categories is beyond the scope of this report, but is proposed for
future reports. In particular, the air quality impacts do not include changes in greenhouse gas
(GHG) emissions.
Within impact categories, impacts are evaluated strictly relative to each other; no attempt
was made to create a common scale to compare the impacts across environmental impacts. For
example, the maximum negative impact for water quality is not comparable to the maximum
negative impact for air quality. There is more confidence in the synthesis conclusions for corn
starch and soybean because we have more experience with them at commercial scales. In
general, we have lower confidence in the degree of environmental impacts for the remaining
feedstocks.
Figure 6-1 presents an overview of potential impacts by the environmental endpoints
called for in EISA Section 204.
Land use. Many of the potential environmental impacts of biofuel production can arise from
land use conversion. An increase in cropland extent in response to increasing demand for
biofuels has been projected in numerous modeling studies, primarily at the expense of pasture
and other less-productive agricultural land. Of the land use conversions allowable under RFS2,
the production of row crops such as corn and soybeans on uncultivated land such as that formerly
enrolled in the Conservation Reserve Program (CRP) will result in the greatest negative
environmental impacts. Since 2006, the year preceding EISA, cropland planted to corn has
increased by almost 10 million acres. However, there is little evidence that substantial amounts
of land have been converted to cropland to date. Recent crop trends suggest that an annual
increase in acres planted to corn has displaced plantings of other row crops. Algae production
has the smallest potential land use implications.
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Chapter 6: Synthesis, Conclusions, and Recommendations
High«—
Low-^—
Low-^—
Wet/Fertile
Diversion of existing crop production
CRP conversion
Chemical inputs and irrigation
Region characteristics
Low
High
High
Dry/Infertile
Most Positive Scenario
Most Plausible Scenario
Most Negative Scenario
KEY
Negligible known impact
Low negative impact
Intermediate negative impact
High negative impact.
I Negligible known impact
I Low positive impact
I Intermediate positive impact
I High positive impact.
Figure 6-1: Most Positive, Negative, and Plausible Environmental Impacts (on a Per Unit
Area Basis) from Feedstock Production
Water quality. Impacts on water quality from biofuels in the United States are, and
likely will be, primarily driven by chemical inputs at the feedstock production stage. Though
there are other impacts, including effluent discharge and other factors associated with processing
biomass into biofuel, these will likely be small in comparison and are already regulated. Impacts
to date from EISA are considered moderately negative, resulting primarily from an
intensification of corn production, which leads to greater erosion and requires more chemical
inputs than other feedstocks, especially of nitrogen fertilizer and pesticides. Increased fertilizer
runoff contributes to eutrophication, coastal hypoxia, and other areas of concern. Conservation
practices, if widely employed, can mitigate these impacts. Cultivation of perennial grasses on
land currently used for row crops offers substantial environmental benefits, though such
conversion is considered unlikely under current market conditions. These grasses require fewer
chemical inputs and have perennial root structures that can lead to lower sediment and nutrient
losses to the surrounding environment. Algae grown using wastewater also offer water quality
benefits.
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Chapter 6: Synthesis, Conclusions, and Recommendations
Water quantity. Water use for feedstock production will likely not change appreciably if
production takes place, as the majority does now, in regions where irrigation is not needed.
However, water availability for other uses may increase if corn replaces CRP that is covered in
relatively high-evapotranspiring perennial grasses. Water use, on the other hand, will increase if
feedstock production expands in regions where irrigation is required to achieve profitable yields.
Irrigation water use will increase more if row crops are cultivated (with an additional possible
requirement if stover is removed from corn fields) than if perennial grasses are cultivated. When
used, irrigation can amount to 100 to 1,000 times the volume of water required to convert
feedstocks into a given volume of biofuel. Moderate forest thinning and residue removal is
unlikely to significantly affect water availability overall. Algae production could consume fresh
water, brackish water, saline water or wastewater. The nature of water availability and all its
associated impacts on human and ecological communities resulting from feedstock production
are difficult to generalize, but impacts are most likely to be adverse in already stressed aquifers
or surface watersheds.
Soil quality. Biofuel feedstock production can impact soil quality in a number ways,
including through erosion, organic matter content and nutrient losses. High stover removal rates
are of particular concern with regard to soil erosion and organic matter. Generally, annual crops,
such as soybeans and corn, result in higher erosion rates, lower soil organic matter content, and
increased nitrogen and phosphorus losses to waterways compared to perennial feedstocks, such
as grasses and woody biomass. However, these impacts may be ameliorated, at least in part, by
the use of conservation practices. Perennial feedstocks may not directly replace row crops, and,
in such a case, their environmental impacts will be relative to other land uses, such as CRP
acreage or abandoned agricultural land. Perennial feedstocks have the potential to improve soil
quality on abandoned or idle agricultural land. The opposite is likely if short-rotation woody
crops (SRWCs) are planted to replace existing forest land currently managed on longer rotations.
Thus, the specific land use conversion will, in large part, determine the soil quality impacts.
Air quality. Combustion of fuels associated with cultivation and harvesting of biofuel
feedstocks and airborne particles (dust) generated during tillage and harvesting result in air
pollutant emissions, which adversely affect air quality, with effects varying by region. Production
of row crops will adversely affect air quality more than non-row crops. Air emissions also result
from the production of fertilizers and pesticides used in corn and soybean cultivation, and their
application in the field.
Biodiversity. Biofuel feedstock cultivation could significantly affect biodiversity through
habitat conversion, especially if CRP lands are put into production. Effects include exposure of
flora and fauna to pesticides; sedimentation and eutrophication in water bodies resulting from
soil erosion and nutrient runoff, respectively; or water withdrawals resulting in decreased
streamflows.
• Forests. Changes in existing forests to shorter harvest intervals for SRWCs and
residue harvesting can decrease habitat availability and biodiversity, while
moderate thinning can increase species diversity and abundances for some
species. Use of riparian buffers to reduce erosion and pesticide and fertilizer
runoff can increase the availability of forest habitat.
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Chapter 6: Synthesis, Conclusions, and Recommendations
• Grasslands. Conversion of grasslands, such as pasture or CRP lands, to row
crops negatively impacts grassland-obligate species, while their conversion to
perennial grass feedstocks is likely to have fewer impacts. Use of grassland
buffers to reduce erosion and pesticide and fertilizer runoff can increase habitat
availability.
• Wetlands. Some agricultural practices can convert small, unregulated wetlands
and increase sediment, nutrient, pesticide, and pathogen runoff into downstream
wetlands; while conservation practices, such as constructed or restored wetlands,
can improve habitat availability for some species and improve freshwater habitat
conditions.
Invasiveness. Corn and soybeans pose negligible risk of becoming weedy or invasive in
the United States. Weed risk assessments predict that in certain regions, switchgrass and some
woody crop species or varieties could become invasive in some regions if cultivated without
preventative measures, but that the perennial grass Giant Miscanthus poses little risk of
becoming invasive. Transport to biofuel production facilities of feedstocks with live seed or
vegetative reproduction could facilitate invasion along transportation corridors. The risk of algae
escape from production with subsequent establishment is highly uncertain.
6.3.2. Biofuel Production, Transport, and Storage
Key conclusions and synthesis of environmental impacts of biofuel production, transport and
storage follow.
Water quality. Pollutants in the wastewater discharged from biofuel production impact
water quality. Biological oxygen demand (BOD), brine, ammonia-nitrogen, and phosphorus are
primary pollutants of concern from ethanol facilities. BOD, total suspended solids, and glycerin
pose the major water quality concerns in biodiesel facility effluent. Actual impacts depend on a
range of factors, including the type of feedstock processed, biorefinery technology, effluent
controls, and water re-use/recycling practices, as well as the facility location and source and
receiving water.
Leaks and spills of biofuel from above-ground, underground, and transport tanks can
contaminate ground, surface, and drinking water. A leaking tank can also present other health
and environmental risks, including the potential for fire and explosion. Enforcement of existing
regulations concerning corrosion protection, leak detection, and spill and overfill prevention will
minimize water contamination. Selection and use of appropriate materials and proper design in
accordance with the applicable material standards or equipment manufacturer recommendations
will help prevent biofuel leaks.
Water quantity. Expansion of biofuel production facilities will increase localized water
withdrawals. Volume of withdrawals will depend on the size and water recycling capacity of the
facility. On a per volume basis, biofuel production uses 100 to 1,000 times less water than
feedstock production. The nature of water availability and associated impacts on human and
ecological communities resulting from biofuel production are most likely to be adverse in
already stressed aquifers or surface watersheds.
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Chapter 6: Synthesis, Conclusions, and Recommendations
Ecosystem health. Effluent discharges high in nutrients, TSS, and other contaminants
decrease aquatic habitat condition and can lead to the loss of sensitive species in rivers and
streams. Increased water withdrawals can lead to more frequent low-flow conditions that reduce
the availability of aquatic habitat. In areas where low flows and high nutrients, TSS or other
contaminants co-occur, aquatic condition will be further reduced.
Air quality. Emissions from biofuel production facilities are generated by a number of
processes, such as fermentation and distillation of resulting mash, as well as the stationary
combustion equipment used for energy production. Because biofuel production facilities are
regulated under the Clean Air Act and subject to state/local permits, enforcement of existing
regulations will mitigate air quality impacts. Emissions can be further reduced through use of
cleaner fuels (e.g., natural gas instead of coal) and more efficient processes and energy
generation equipment. Using energy-saving technologies such as combined heat and power
(CHP) is an effective means to reduce air emissions associated with biofuel production (both
ethanol and biodiesel).
Air quality will be affected by emissions from biofuel transport via rail, barge, and tank
truck and by evaporative, spillage, and permeation emissions from transfer and storage activities.
However, the impacts are not expected to be significant.
6.3.3. End-Use
Air Quality: End-use impacts are primarily air-quality impacts. Evaporative and tailpipe
emissions from biofuel combustion show great variability due to a range of factors, including the
vehicle age, how the vehicle is operated, and ambient temperatures. For ethanol, emissions are
expected to be higher for some pollutants (such as nitrogen oxides and hydrocarbons) and lower
for others, with large decreases in carbon monoxide emissions in particular. Biodiesel
combustion also exhibits a pattern of increases (nitrogen oxide emissions) and decreases (PM,
CO, and HC emissions). Emissions from ethanol use are independent of feedstock; in contrast,
emissions from biodiesel use differ according to the feedstock. Particulate matter, N2O, and CO
emissions are higher for plant-based biodiesel than for animal-based biodiesel.
In EPA's RFS2 RIA (U.S. EPA, 2010a), these emissions changes were used in air quality
models to assess anticipated impacts on ambient concentrations in 2022 as a result of the EISA-
mandated biofuel volumes in comparison to two reference scenarios. The effects of ethanol or
biodiesel were not separated: rather, the entire landscape of biofuels was assessed collectively.
Details of note include findings for ozone and PM2.5 levels (two pollutants of ongoing concern
because concentrations already exceed National Ambient Air Quality Standards in many areas of
the country) and for air toxics.
EISA-mandated biofuels production is expected to increase PM levels in some areas and
decrease them in others. The increases are expected as a result of biofuel production and
transportation, which is more prevalent in the Midwest. Ozone concentrations over much of the
United States are expected to rise: however, ozone air quality improvements are projected in a
few highly populated areas that currently have poor air quality (U.S. EPA, 2010a). Ground-level
ozone is formed by the reaction of VOCs and NOx in the atmosphere in the presence of heat and
sunlight. The projected ozone changes described in the RIA are likely a result of the emissions
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Chapter 6: Synthesis, Conclusions, and Recommendations
changes due to the increased volumes of renewable fuels combined with the photochemistry
involved, the different background concentrations of VOCs and NOx in different areas of the
country, and the different meteorological conditions in different areas of the country.
The RIA's air quality impacts assessment also included compounds that were identified
as national- and regional-scale cancer and noncancer risk drivers in past National-Scale Air
Toxics Assessments and were also likely to be significantly impacted by the standards. These
compounds include benzene, 1,3-butadiene, formaldehyde, acetaldehyde, and acrolein. In
addition to these explicit model species, photochemical processes mechanisms model the
formation of some of these compounds in the atmosphere from precursor emissions. This aspect
of the air quality model requires inventories for a large number of precursor compounds,
including compounds such as ethene and methane, and uses atmospheric reaction pathways
including that of aldehydes and peroxyacetyl nitrate (PAN). Thus, although numerous other
species are not explicitly discussed, their impacts are accounted for in the RIA air quality
analysis. Refer to the RIA for additional details and results (U.S. EPA, 2010a).
The RIA found some localized impacts for air toxics, but relatively small changes in
national average ambient concentrations. Some urban areas may have small decreases of
acetaldehyde and formaldehyde, while some ethanol-producing regions may have small
increases (less than 1 percent). Concentrations of 1,3-butadiene and acrolein are expected to
decrease in some southern areas and increase in some northern areas with high altitudes. Small
decreases (1 to 10 percent) of benzene are expected.
Finally, the RIA also found the renewable fuel volumes required by RFS2 lead to
significant nationwide increases in ambient ethanol concentrations. Increases ranging between 10
to 50 percent are seen across most of the country. The largest increases (more than 100 percent)
occur in urban areas with high amounts of nonroad emissions and in rural areas associated with
new ethanol plants (U.S. EPA, 2010a).
6.4. Conclusions
Evidence to date from the scientific literature suggests that current environmental impacts
from increased biofuels production and use associated with EISA 2007 are negative but
limited in magnitude.
• Environmental impacts along the supply chain are greatest at the feedstock
production stage. Most activities, processes, and products, particularly those
occurring after feedstock production, are regulated and subject to limitations.
• Current environmental impacts are largely the result of corn production.
Corn starch-derived ethanol constituted 95 percent of the biofuel produced in
2009. In general, feedstock demand has been met by diverting existing corn
production or by replacing other row crops with corn, resulting in modest
additional environmental impacts.
Published scientific literature suggests a potential for both positive and negative
environmental effects in the future.
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Chapter 6: Synthesis, Conclusions, and Recommendations
• Technological advances and market conditions will determine what
feedstocks are feasible, and where and how they will be cultivated.
• The magnitude of effects will be largely determined by the feedstock(s)
selected, land use changes, and cultivation practices.
• Overall impacts given most plausible land use changes and production
practices will likely be neutral or slightly negative (Figure 6-1). More adverse
or beneficial environmental outcomes are possible.
• Second-generation feedstocks have a greater potential for positive
environmental outcomes relative to first-generation feedstocks (Figure 6-1).
However, current production levels of second-generation biofuels are negligible
and limited by economic and technological barriers.
EISA goals for biofuels production can be achieved with minimal environmental impacts if
existing conservation and best management practices are widely employed, concurrent
with advances in technologies that facilitate the use of second-generation feedstocks (Figure
6-1).
• The feedstocks considered in this report all have the potential to support
sustainable domestic energy production. Realizing this potential will require
implementation and monitoring of conservation and best management practices,
improvements in production efficiency, and implementation of innovative
technologies at the commercial scale.
• International partnerships and federal coordination are needed to accelerate
progress towards sustainable and secure energy production.
6.5. International Considerations
Increases in U.S. biofuel production and consumption volumes will affect many different
countries as trade patterns and prices adjust to equate global supply and demand. This will result
in environmental impacts, both positive and negative, including effects from land use change and
effects on air quality, water quality, and biodiversity. Direct and indirect land use changes could
occur internationally as the United States and other biofuel feedstock-producing countries alter
their agricultural sectors to allow for greater biofuel production. Many locations where biofuel
production is growing are areas of high biodiversity value. For example, Brazil (sugar ethanol)
contains ecosystems with high biodiversity. Depending on where biofuel feedstock production
occurs, and the manner in which it occurs, impacts to biodiversity could be significant. However,
because corn ethanol is limited by the RFS2 and is likely to reach this limit in the next few years,
these international impacts projected in the RIA could level off as corn starch ethanol production
levels off or is replaced by more advanced technologies.
As with domestic production, the choice of feedstock, how and where it is grown, the
resulting land use changes, and how it is produced and transported will have a large effect on
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Chapter 6: Synthesis, Conclusions, and Recommendations
how biofuel production and use affects water quality and availability, air quality (e.g., due to
emissions from burning crop residue), and biodiversity. The specific impacts will reflect a
country's particular circumstances.
6.6. Recommendations
EISA Section 204 specifies that EPA must include recommendations for actions to
address any adverse impacts identified in this report. Responding specifically to this request
requires a clear understanding of biofuel impacts and their causes and the recognition of the high
degree of uncertainty in many areas surrounding the progress of the technologies and
implementation of mitigation procedures to ameliorate impacts. For corn starch and soybean
production, the impacts are relatively well understood, but more information is needed about the
adverse impacts associated with production of other feedstocks and with the production and use
of advanced biofuel. This section presents four recommendations to address adverse impacts.
Because biofuel impacts cross multiple topics and EPA responsibilities, EPA likely will address
these recommendations through continued and strengthened cooperation with other federal
agencies and international partners.
6.6.1. Comprehensive Environmental Assessment
The biofuel industry is poised for significant expansion in the next few years. A variety
of new technologies will likely be implemented and old technologies will be modified to meet
the demands of affordable and sustainable alternatives to petroleum fuel. As emphasized by
Congress in requiring triennial biofuel impact assessments, it is important to evaluate the
environmental implications associated with the ongoing growth of the dynamic biofuel industry.
While there is currently available sufficient scientific information to inform environmental
decisions, the inherent complexity and uncertainty of environmental impacts across the biofuel
supply chain present a challenge to providing definitive assessments and further research is
necessary.
RECOMMENDATION: Develop and evaluate environmental life cycle assessments for
biofuels. With this report, EPA, USD A, and DOE have begun to develop a framework and
partnership that provide an important foundation for future assessments. Future assessments will
address advanced biofuel production associated with specific feedstocks and associated
byproducts and provide a context for comparison to fossil fuels. As described in Chapter 7,
future assessments should be comprehensive, region-specific and address the major
environmental parameters affected by increased biofuel production and use. These assessments
will identify gaps and uncertainties in the knowledge base, inform the design and implementation
of monitoring strategies and measures for evaluating impacts, provide comprehensive tools for
comparing and evaluating development options, and provide the scientific bases for regulatory
agencies and the biofuel industry to make environmentally conscious decisions.
6.6.2. Coordinated Research
The expansion of the biofuel industry will be shaped to a large degree by the research
behind the technological developments that make biofuel production feasible. It will be
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Chapter 6: Synthesis, Conclusions, and Recommendations
important for the scientific infrastructure that supports policy and decision-making to keep pace
with industry developments.
RECOMMENDATION: Ensure the success of current and future environmental biofuel
research through improved cooperation and sustained support. The Biomass Research and
Development Board, co-chaired by DOE and USD A, currently monitors interagency cooperation
in biofuel research. The Board recently proposed that an inventory be conducted of federal
activities and jurisdictions relevant to environmental, health, and safety issues associated with
biofuel production in order to identify issues of concern, research needs, and mitigation options.
Efforts to adjust and expand existing research programs to conduct biofuel-relevant research
have been initiated. Prioritization and collaboration by the research community will be critical to
provide meaningful results in the near term and to meet the wide variety of research needs,
including many that have already been identified, that will be important to the industry and to
appropriate regulatory oversight.
6.6.3. Mitigation of Impacts from Feedstock Production
As the biofuel industry expands, it will be important to optimize benefits while
minimizing adverse impacts. Because many of the known adverse impacts are due to feedstock
production, this report has described the potential for mitigation of those impacts through the
adoption of conservation systems and practices on farms. USDA has a variety of programs that
help agriculture producers implement these conservation systems. As USDA's Conservation
Effects Assessment Project (CEAP) report on the upper Mississippi River basin demonstrates,
much more needs to be done to control pollution from agriculture, especially from nitrogen. A
collaborative effort is needed to develop and foster application of consistent and effective
monitoring and mitigation procedures to protect the environment and conserve biodiversity and
natural resources as biofuel production expands and advanced biofuels are commercially
produced.
RECOMMENDATION: Improve the ability of federal agencies (within their existing
authorities) and industry to develop, implement, and monitor best management and
conservation practices and policies that will minimize negative environmental impacts and
maximize the positive environmental effects of biofuel production and use. This will involve
coordination among diverse stakeholders, including state agencies, research scientists, and
landowners. These policies and practices should be aligned and assessed within the context of
the environmental life cycle assessment and take a multi-factor and multi-scale view of biofuels
and their potential environmental effects. Priority areas for development include (1) improved
containment processes and technologies that minimize environmental exposure from air
emissions and runoff into surface and ground water and (2) methods to monitor, track, and report
biofuel environmental impacts.
6.6.4. International Cooperation to Implement Sustainable Biofuel Practices
EISA specifically identifies "significant emissions from land use change" as a potential
environmental impact stemming from domestic biofuel production and consumption. This
concern is relevant to all countries engaged in biofuel production, but as the United States
increases domestic production of corn starch ethanol and soybean diesel, exports of corn and
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Chapter 6: Synthesis, Conclusions, and Recommendations
soybean for agricultural or other uses are expected to decline, which may result in indirect land
use change in the form of land conversion to agriculture in other countries. Additional biofuel
produced to meet the EISA mandates will potentially lead to increases in acreages of
international cropland, although these increases may level off after 2015 (see Section 5.3).
RECOMMENDATION: Engage the international community in cooperative efforts to
identify and implement sustainable biofuel and land use practices that minimize
environmental impact. U.S. and international capacity to minimize the consequences of land
use change will depend not only on the willingness of governments and industry to make
environmentally sound choices regarding biofuel production, processing, and use, but also on the
availability of cost-effective mitigation strategies and sustainable land use practices. The United
States can significantly contribute to such an effort by actively engaging the scientific
community and biofuel industry to collaboratively develop the body of knowledge needed to
support sound environmental decision-making. This effort will be facilitated by a greater
understanding and appreciation of how increased biofuel demand may impact the environment
internationally, particularly in countries that are most active, or most likely to become active, in
biofuel production.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
7. ASSESSING ENVIRONMENTAL IMPACTS FROM BIOFUELS: 2013 TO 2022
7.1. Introduction
In requiring EPA to report triennially under EISA Section 204, Congress recognized that
the environmental and resource conservation impacts of increased biofuel production and use
will be dynamic, changing over time in both nature and scope, based on the amount, type, and
location of biofuels produced and used. This first triennial Report to Congress, which reflects the
state of scientific knowledge as of July 2010, is a first step toward identifying information that
supports future assessment of environmental impacts from increased biofuel production and use.
This chapter outlines an approach EPA may use for its future assessments, beginning
with the second (2013) report to Congress. In developing future assessments, EPA will work
closely with the U.S. Departments of Agriculture and Energy (USDA and DOE), and other
interested federal agencies, such as the Department of Defense, and will seek extensive input
from industry and other stakeholders and peer review from the scientific community to create
substantive, science-based analyses that facilitate environmental decision-making. Future
assessments will benefit from advances in the science of environmental assessment and increased
availability of relevant research results on this important topic.
EPA anticipates that additional research and analyses will allow for more robust and
quantitative assessments of biofuel environmental impacts than are reported here. For example,
life cycle assessment (LCA) tools and approaches that are currently used for evaluating "cradle-
to-grave" resource consumption and waste disposal for specific products can be integrated into
risk assessment to form a powerful composite approach for assessing environmental impacts. An
approach to more comprehensive environmental analyses that is consistent with the integration
of LCA and risk assessment methods has been used in different assessments (Davis and Thomas,
2006; Davis, 2007). This approach would necessitate extending consideration of factors across
the entire biofuel life cycle, including current and future feedstock production and biofuel
conversion, distribution, and use. The Agency has already applied LCA to assess greenhouse gas
(GHG) emissions as part of its revised Renewable Fuel Standard (RFS2) program (U.S. EPA,
2010a) and could adapt this approach to analyze other aspects of biofuel production and use,
such as water consumption; evaluation of fossil fuels versus biofuels; net energy balance;
production and use scenarios; and market impacts (economics).
7.2. Components of the Second Assessment
This section briefly describes key components that EPA will consider in conducting the
next report. A comprehensive environmental assessment framework would facilitate evaluation
and quantification of risk and benefits of biofuel production and use. Such a framework would
integrate models such as the Soil Water and Assessment Tool (SWAT), the Environmental
Policy Integrated Climate Model (EPIC), the Community Multiscale Air Quality Model
(CMAQ), and the Daily Century Model (DAYCENT). These modeling efforts would allow
greater quantification of the potential impacts of biofuel production and allow for mapping their
spatial distribution. For example, the use of EPIC could provide estimates of the soil erosion risk
of growing biofuel feedstocks on Conservation Reserve Program (CRP) lands.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
A comprehensive framework would also include LCA and environmental risk
assessment. The latter could be used to systematically assess environmental risks, both human
health risks and ecological risks, for each stage in the life cycle, as well as the potentially
cumulative impacts. Conceptual models will illustrate the important factors being considered in
each stage of the life cycle and indicate how these factors are interrelated. Where possible,
environmental indicators and other metrics will be developed over the next several years to track
the impacts of biofuel production and use throughout its life cycle and measure the effectiveness
of regulatory and voluntary practices in ameliorating these impacts. A scenario-based approach
is currently envisioned to provide a comparative basis for projecting and assessing how biofuel
production and use might affect the environment in future years. Finally, the next assessment
will include other components, such as a comparison to fossil fuels, net energy balance, and
analysis of market impacts, that are important to evaluating biofuel impacts.
7.2.1. Life Cycle Assessments
LCAs have been widely used to assess the potential benefits and potential pitfalls for bio-
ethanol as a transportation fuel (Von Blottnitz and Curran, 2007; Gnansounou et al., 2009). The
majority of such analyses have focused on particular components such as GHG emissions and
energy balances (Hill, 2009). Economic models can provide estimates of environmental costs by
monetizing ecosystem and human health effects (NRC, 201 Ob) with varied results depending on
the assumptions and input parameters driving the assessments. In some cases, the scientific
community seems close to reconciling the various assumptions used by different investigators
(Anex and Lifset, 2009). To better address the EISA reporting mandate, however, a broader
profile of potential environmental impacts should be considered. This approach has been used in
several studies (Von Blottnitz and Curran, 2007) and applied to evaluating trade-offs for fuel
options (Davis and Thomas, 2006). As part of the next assessment, EPA anticipates using LCA
in a broad context, one that considers a full range of potential environmental effects and their
magnitude. A variety of environmental LCA approaches have been developed that would prove
useful for such an effort (Puppan, 2002; Ekvall, 2005; Hill et al., 2006; Landis et al., 2007;
Duncan et al., 2008).
7.2.2. Environmental Risk Assessment
Environmental risk assessment will be fundamental for systematically evaluating the
human and environmental impacts of the activities involved in biofuel production and use.
Environmental risk assessment can be used to estimate the risks associated with each stage of the
biofuel life cycle, from production of raw materials, through transportation and consumption, to
the generation of waste products. Environmental risk assessment is initiated by clearly
articulating the problem (i.e., problem formulation); describing the critical sources, stressors, and
effects, and the linkages among these factors; quantifying human/ecological exposure and
effects; and subsequently characterizing and estimating the risks associated these effects.
Environmental risk assessment will identify which stages in the biofuel life cycle contribute the
greatest risk so that more informed risk management practices can be developed and
implemented for these stages.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
7.2.3. Human Health Assessment
Increasing biofuel use presents the potential for distinct health effects separate from the
known impacts of fossil fuels. The fate and transport of these new fuel blends in the environment
and the subsequent exposures and human health effects have not been fully studied. Drawing
definitive conclusions on health impacts is not realistic at this time, given the unknowns
surrounding the feedstocks, technologies, and fuel blends that will be used to meet target
volumes, and the relatively limited availability of toxicological data to directly evaluate the
potential health effects of the various emissions.
Health effects will be assessed in the next report, provided adequate data are available. In
examining the health risks and benefits of increased biofuel use, it will be important to
understand the unique characteristics of the new fuel blends, how and when releases occur, the
fate and transport of these releases, the relevant routes and duration of exposures to humans, and
the toxic effects of those exposures. Both individual and population exposures will be important
to consider. For example, populations in regions that both produce and use biofuel will
experience different exposures than those in regions that only use the fuel. Individuals within the
same region may experience different exposures (i.e., occupational, consumer, or public
exposures), and vulnerable populations may be at greater risk of adverse effects, depending on
their sensitivity.
7.2.4. Conceptual Models
A number of tools are available for use in problem formulation, including conceptual
diagrams, which hypothesize relationships between activities and impacts. These diagrams can
support multiple purposes, including defining system boundaries; enhancing understanding of
the system being analyzed; and supporting communication among assessors, between assessors
and stakeholders, and, ultimately, with risk managers.
The information provided in Chapters 3, 4, and 5 of this current assessment lays a
foundation for constructing initial conceptual models to show relationships among biofuel
activities and impacts. Figures 7-1 and 7-2 present generalized conceptual models for feedstock
and biofuel production, respectively. Appendix C provides detailed conceptual diagrams for each
of the feedstocks and fuels considered in this report. Based on the information gathered during
this current assessment, the diagrams show the activities (e.g., crop rotation, water use)
associated with the model's domain area and how, through a series of relationships indicated
with lines and arrows, these activities are associated with products and impacts. These diagrams
are the first step in linking evidence from the literature to show the degree of support for
different pathways. They can also lead to mathematically simulating the system and quantifying
impacts. Diagrams such as these will be important tools for assessments in EPA's future reports
to Congress.
7.2.5. Monitoring, Measures, and Indicators
EPA's ability to accurately assess impacts attributable to biofuels production and use will
depend on having timely, relevant, and accurate monitoring information that tracks potential
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
impacts. It will also depend on how effective regulatory and voluntary management practices,
risk management practices, and other measures are in protecting the environment.
Current environmental monitoring by various agencies looking at the impacts of
traditional land management and energy impacts can provide helpful information, and targeted
monitoring for potential biofuel impacts may be needed. Improved monitoring systems will
require a collaborative effort across multiple agencies and other organizations. Improved
monitoring of indicators and measures are important for a variety of environmental effects,
including GHG emissions, human and ecological health, eutrophication, and many other effects.
Metrics surrounding these effects will inform decisions at all levels along the biofuel supply
chain and well beyond the scope of the individual decision.
7.2.6. Scenarios
EPA's next report to Congress will assess the environmental impacts of all five stages in
the biofuel supply chain (see Figure 2-2). One approach may be to create scenarios based on
volumetric biofuel requirements for 2022 as presented in the RFS2 (see Table 2-1). Three
illustrative scenarios are as follows:
• Scenario A. 2022 RFS2-projected feedstock mix produced with comprehensive
conservation systems and efficient technologies. Conservation systems include
maintenance of crop rotation practices; increased use of conservation tillage,
nutrient management, and efficient irrigation systems; crop breeding that results
in improved yields and decreased fertilizer, pesticide, and irrigation inputs;
minimal expansion of crop land to uncultivated land; and harvest of stover and
woody biomass that minimizes soil erosion and nutrient depletion. Efficient
technologies include improved fuel conversion processes that require fewer
production inputs like energy and fresh water.
• Scenario B. 2022 RFS2-projected feedstock mix produced with minimal
conservation practice implementation and current technologies. Conventional
production practices and non-conservation practices that could be used include
decreased crop rotation; minimal use of conservation tillage, nutrient
management, and water-saving irrigation; exclusive reliance on increased
fertilizer, pesticide, and irrigation inputs to improve crop yields; conversion of
CRP and marginal land to crop production that requires fertilizer and irrigation;
and harvest of stover and woody biomass that results in erosion and decreased soil
nutrients. Current technologies are those now used to convert biomass to fuel with
energy and fresh water inputs remaining at current levels.
• Scenario C. 2022 conventional feedstock mix (corn starch, corn stover, and
soybean) produced with minimal conservation practice implementation. Practices
are as in Scenario B, but no perennial grasses, woody biomass, or algae are used
as feedstocks to fulfill RFS2 volumetric requirements.
7-4
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demand LEGEND
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Feedstock Production
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Figure 7-2: Conceptual Diagram of the Potential Environmental Impacts of Biofuel
Production and Use
Assessing Environmental Impacts from Biofuels: 2013 to 2022
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
As noted earlier, the landscape of feedstock/biofuel production, conversion, and use is
highly dynamic and constantly evolving. Which feedstocks and technologies are used and to
what extent they are used will be influenced by technological developments and market forces
that are difficult to predict. Development of scenarios for future assessments will need to model
or otherwise account for key factors that influence the biofuel market dynamics and associated
environmental impacts. These factors include:
• Regional considerations. In general, biofuel conversion facilities will tend to be
sited at reasonable distances from feedstock production areas, because cost
considerations limit the distances over which biofuel feedstocks can be
transported. Consequently, environmental impacts of both feedstock production
and biofuel conversion will tend to be concentrated in particular regions.
• Scale and volume of future commercial biofuel operations. Future
development and application of commercially viable biofuel technologies will
change the nature of energy feedstocks and conversion processes in use, as well as
the scale of their operation. Fossil fuel prices can affect investment in, and
adoption of, new biofuel technologies. While the continued use of corn starch for
ethanol will likely not change, the future portfolio of feedstocks and biofuels is
likely to vary from those used in 2010. However, which feedstock and biofuel
will actually be used and to what extent is highly uncertain and largely dependent
on technology advances for the production of second-generation feedstocks.
• Hybrid processes. Biofuel conversion processes (e.g., biochemical and
thermochemical processes) may evolve in the future to be hybrid processes that
would produce not only biofuel but also synthetic chemicals and other industrial
co-products. Integrated biorefmeries may have the ability to make use of a
biofuel-only or a hybrid conversion platform. Each new conversion option will
present its own range of potential environmental impacts.
• Changes in vehicle technologies. Changes in vehicle technologies, patterns of
vehicle sales, and fueling behavior will be needed to accommodate higher ethanol
production volumes. Conversely, changes in vehicle technologies driven by other
considerations, such as the development of plug-in hybrid electric or all-electric
vehicles, could change the demand for liquid biofuels.
• Changes in agricultural practices due to biofuel production and implications
for environmental impacts. Recent increases in ethanol production have
expanded the market demand for corn grain, and farmers have responded to this
increased demand by, for example, changing crop rotation practices and/or
replacing other row crops with corn. It is not clear what the effects of production
shifts, agricultural residue use, and associated farm-level management practice
changes will be in the short term.
7.2.7. Other Components
In addition to the above components, EPA plans to include in the next assessment several
analyses that provide important perspective for understand and evaluating the impacts of biofuel
production and use, as described below.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
Comparison of fossil fuel to biofuel. While this current report provides a starting point
for comparing the relative impacts associated with a range of different biofuel feedstock and
production processes, it is critical to assess biofuel impacts in the larger context of the
conventional petroleum fuels that are being displaced under the RFS2 mandates. Ideally, this
comparison would cover the full life cycle for each fuel. Such an evaluation would facilitate
comprehensive assessment of the relative costs and benefits of RFS2 beyond GHG impacts, and
support identification of effective mitigation measures for key impacts. This type of evaluation
has been recommended by the National Advisory Council for Environmental Policy and
Technology (NACEPT) as a means of conducting integrated environmental decision-making
(NACEPT, 2008). Given the limitations of currently available information, a comparative
assessment of petroleum fuel and biofuel impacts would be largely qualitative, with significant
data gaps and uncertainties. Nevertheless, EPA anticipates that even a qualitative comparative
analysis will be an important component of the next assessment.
Net energy balance. Net energy balance (i.e., the amount of energy used to develop
biofuels compared to the energy value derived from biofuels) is an important metric that will
likely be addressed in the next assessment. It enables comparison of biofuel produced from
different feedstocks and via different conversion processes, as well as comparison between
biofuel and gasoline. The net energy balance will include consideration of energy embedded in
co-products of the fuel conversion process. For example, increases in corn ethanol production
will increase the amount of co-products used in animal feed, which in turn displaces whole corn
and soybean meal used for the same purpose—the "displaced" energy is credited to the ethanol
system and offsets some of the energy required for production (Hammerschlag, 2006; Liska et
al., 2008).
Market impacts. Biofuels displace fossil energy resources, but also consume petroleum
products, natural gas, electricity (much of which comes from nonrenewable energy sources), and
even coal at different points along their supply chain. Consequently, changes in fossil fuel prices
will impact the economics of biofuel production in unpredictable ways. The next report will
likely address market impacts and incorporate modeling of coupled energy systems and
agricultural markets.
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Chapter 8: References
8. REFERENCES
Adegbidi, HG; Volk, TA; White, EH; Abrahamson, LP; Briggs, RD; Bickelhaupt, DH. 2001.
Biomass and nutrient removal by willow clones in experimental bioenergy plantations in
New York State. Biomass and Bioenergy 20(6): 399-411.
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Appendix A
Appendix A
Glossary and Acronyms
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Appendix A
advanced biofuel: A renewable fuel, other than ethanol derived from corn starch, that has life
cycle greenhouse gas emissions that are at least 50 percent less than life cycle GHG emissions
from petroleum fuel. Cellulosic biofuels must achieve a 60 percent reduction in GHG to get
credit for being "advanced."
agricultural residue: Plant parts, primarily stalks and leaves that are not removed from fields
used for agriculture during harvesting of the primary food or fiber product. Examples include
corn stover (stalks, leaves, husks, and cobs), wheat straw, and rice straw.
algae: Plant-like organisms (usually photosynthetic and aquatic) that do not have true roots,
stems, leaves, or vascular tissue, and that have simple reproductive structures. Algae are
distributed worldwide in the sea, in fresh water, and in wastewater. Most are microscopic, but
some are quite large (e.g., some marine seaweeds that can exceed 50 meters in length).
B20: A fuel mixture that includes 20 percent biodiesel and 80 percent conventional diesel and
other additives. Similar mixtures, such as B5 or BIO, also exist and contain 5 and 10 percent
biodiesel, respectively.
B100: Pure (i.e., 100 percent) biodiesel, also known as "neat biodiesel."
best management practices (BMPs): The techniques, methods, processes, and activities that are
commonly accepted and used to facilitate compliance with applicable requirements, and that
provide an effective and practicable means of avoiding or reducing the potential environmental
impacts.
biodiesel (also known as "biomass-based diesel"): A renewable fuel produced through
transesterification of organically derived oils and fats. May be used as a replacement for or
component of diesel fuel. According to 40 CFR 80.1401, biodiesel means "a mono-alkyl ester
that meets ASTM D6751 ('Standard Specification for Biodiesel Fuel Blend Stock (B100) for
Middle Distillate Fuels')."
biodiversity: The variety and variability among living organisms and the ecological complexes
in which they occur. Biodiversity can be defined as the number and relative frequency of
different items, from complete ecosystems to the biochemical structures that are the molecular
basis of heredity. Thus, the term encompasses ecosystems, species, and genes.
biofuel: Any fuel made from organic materials or their processing and conversion derivatives.
biofuel blend: Fuel mixtures that include a blend of renewable biofuel and petroleum-based fuel.
This is opposed to "neat form" biofuel that is pure, 100 percent renewable biofuel.
biofuel distribution: Transportation of biofuel to blending terminals and retail outlets by a
variety of means, including rail, barge, tankers, and trucks. This almost always includes periods
of storage.
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Appendix A
biofuel end use: Combustion of biofuel in vehicles and various types of engines, usually as a
blend with gasoline or diesel, or in some cases in neat form.
biofuel life cycle: All the consecutive and interlinked stages of biofuel production and use, from
feedstock generation to biofuel production, distribution, and end use by the consumer.
biofuel production: The process or processes involved in converting a feedstock into a
consumer-ready biofuel.
biofuel supply chain: The five main stages involved in the life cycle of a biofuel: feedstock
production, feedstock logistics, fuel production, fuel distribution, and fuel use.
biogenic: Produced by living organisms or a biological process.
biomass: Any plant-derived organic matter (e.g., agricultural crops and crop wastes; wood and
wood wastes and residues; aquatic plants; perennial grasses).
biomass-based diesel: See "biodiesel" above. Biomass-based diesel includes non-co-processed
renewable diesel, which does not use the transesterification technology.
According to 40 CFR 80.1401, biomass-based diesel is "a renewable fuel that has lifecycle
greenhouse gas emissions that are at least 50 percent less than baseline lifecycle greenhouse gas
emissions and meets all of the following requirements:
• Is a transportation fuel, transportation fuel additive, heating oil, or jet fuel;
• Meets the definition of either biodiesel or non-ester renewable diesel; and
• Registered as a motor vehicle fuel or fuel additive under 40 CFR part 79, if the
fuel or fuel additive is intended for use in a motor vehicle.
Renewable fuel that is coprocessed with petroleum is not biomass-based diesel."
cellulosic biofuel: A renewable fuel derived from lignocellulose (a plant biomass composed of
cellulose, hemicellulose, and lignin that is a main component of nearly every plant, tree, and
bush in meadows, forests, and fields). Lignocellulose is converted to cellulosic biofuel by
producing sugars from the residual material, mostly lignin, and then fermenting, distilling, and
dehydrating this sugar solution. According to 40 CFR 80.1401, cellulosic biofuel is "renewable
fuel derived from any cellulose, hemicelluloses, or lignin that has lifecycle greenhouse gas
emissions that are at least 60 percent less than the baseline lifecycle greenhouse gas emissions."
Conservation Reserve Program (CRP): A U.S. Department of Agriculture program that
provides technical and financial assistance to eligible farmers and ranchers to address soil, water,
and related natural resource concerns on their lands in an environmentally beneficial and cost-
effective manner. It encourages farmers to convert highly erodible cropland or other
environmentally sensitive acreage to vegetative cover, such as tame or native grasses, wildlife
plantings, trees, filter strips, or riparian buffers. Farmers receive an annual rental payment for the
term of the multi-year contract.
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Appendix A
conservation tillage: Any cultivation system that leaves at least one-third of the land surface
covered with residue after planting in order to reduce soil erosion and conserve soil productivity.
One example would be "no-till," where fields are not tilled at all and crops are planted directly
into the existing residue. Other variations include "strip-till" or "ridge-till," which remove some,
but not all, of the residue from the harvested area.
conventional biofuel: In the context of this report, "conventional biofuel" refers to ethanol
derived from corn starch that does not lead to at least a 50 percent reduction in greenhouse gas
emissions compared to petroleum. EISA 2007 requires conventional biofuel to achieve a 20
percent reduction in life cycle GHG emissions compared to gasoline.
corn stover: The stalks, leaves, husks, and cobs that are not removed from the fields when corn
is harvested.
crop yield: The quantity of grains or dry matter produced from a particular area of land. (In this
report, crop yield is most often measured in corn or soybean bushels per acre.)
direct land use change: In the context of biofuel, "direct land use change" refers to land
conversion that is directly related and easily attributable to the biofuel supply chain. For
example, conversion by a U.S. farmer of grasslands to corn for ethanol would be considered a
direct land use change.
double cropping: The process of planting two different crops (not including cover crops) on the
same piece of land over the course of a growing season.
dry milling: A process for producing conventional corn starch ethanol in which the kernels are
ground into a fine powder and processed without fractionating the grain into its component parts.
Most ethanol comes from dry milling.
E10: A fuel mixture of 10 percent ethanol and 90 percent gasoline based on volume.
E85: A fuel mixture of 85 percent ethanol and 15 percent gasoline based on volume.
ecosystem health: The ability of an ecosystem to maintain its metabolic activity level and
internal structure and organization, and to resist external stress over time and space scales
relevant to the ecosystem.
effluent: Liquid or gas discharged in the course of industrial processing activities, usually
containing residues from those processes.
Energy Independence and Security Act (EISA): Signed into law as Public Law 110-140 on
December 19, 2007, this legislation established energy management goals and requirements
while also amending portions of the National Energy Conservation Policy Act. EISA's stated
goals are to move the U.S. toward greater energy independence and security; increase production
of clean renewable fuels; protect consumers; increase the efficiency of products, buildings, and
vehicles; promote research on and deploy greenhouse gas capture and storage options; and
improve the energy performance of the federal government.
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Appendix A
environmental life cycle assessment: In the context of this report, an environmental life cycle
assessment is an assessment in which the LCA methodology (see "life cycle assessment") is
applied to address the full range of potential environmental impacts over all environmental
media.
ethanol (also known as "bioethanol"): A colorless, flammable liquid produced by fermentation
of sugars. Ethanol is generally blended with gasoline and used as a fuel oxygenate.
eutrophication: Nutrient enrichment of aquatic ecosystems, in which excessive nutrient levels
cause accelerated algal growth, which in turn can reduce light penetration and oxygen levels in
water necessary for healthy aquatic ecosystems. Eutrophication can cause serious deterioration of
both coastal and inland water resources and can lead to hypoxia.
feedstock: In the context of biofuel, "feedstock" refers to a biomass-based material that is
converted for use as a fuel or energy product.
feedstock logistics: All activities associated with handling, storing, and transporting feedstocks
after harvest to the point where the feedstocks are converted to biofuel.
feedstock production: All activities associated with cultivation and harvest of biofuel feedstock.
filter strip: A strip or area of herbaceous vegetation that may reduce nutrient loading, soil
erosion, and pesticide contamination by removing soil particles and contaminants from overland
water flow.
forest residue: Includes tops, limbs, and other woody material not removed in forest harvesting
operations in commercial hardwood and softwood stands.
forest thinning: Removal of trees from overgrown forests to reduce forest fire risk or increase
forest productivity. These trees are typically too small or damaged to be sold as round wood but
can be used as biofuel feedstock.
genetically engineered feedstock: Plants, trees, and other organisms that have been modified by
the application of recombinant DNA technology and produce the biomass-based material
converted for use as a fuel or energy product.
greenhouse gases (GHGs): Gases that trap the heat of the sun in the Earth's atmosphere,
producing the greenhouse effect. Greenhouse gases include water vapor, carbon dioxide,
hydrofluorocarbons, methane, nitrous oxide, perfluorocarbons, and sulfur hexafluoride.
hemicellulose: any of various plant polysaccharides less complex than cellulose and easily
hydrolysable to monosaccharides (simple sugars) and other products.
hybrid: A plant species created from the offspring of genetically different parents, both within
and between species. Hybrids combine the characteristics of the parents or exhibit new ones.
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Appendix A
hypoxia: The state of an aquatic ecosystem characterized by low dissolved oxygen levels (less
than 2 to 3 parts per million) due to accelerated algal growth and reduced light penetration
because of excessive nutrient levels (eutrophication). Low dissolved oxygen can reduce fish
populations and species diversity in the affected area.
indirect land use change: In the context of biofuel, "indirect land use change" refers to land
conversion that occurs as a market response to changes in the supply and demand of goods other
than biofuel (e.g., food commodities) that result from changes in biofuel demand. For example,
clearing of foreign land to plant corn as a food crop in response to reduced U.S. corn exports
caused by increased use of U.S. corn to produce ethanol is considered to be an indirect land use
change.
integrated pest management (IPM): An environmentally sensitive approach to pest
management that uses current, comprehensive information on the life cycles of pests and their
interaction with the environment to manage pest damage by the most economical means, and
with the least possible hazard to people, property, and the environment.
invasive plant (also called an invasive or a noxious plant): A novel species or genotype whose
introduction does or is likely to cause economic or environmental harm or harm to human health.
land cover: Vegetation, habitat, or other material covering a land surface.
land use: The human use of land involving the management and modification of natural
environment or wilderness into human-dominated environments such as fields, pastures, and
settlements.
legumes: Plants belonging to the pea family that typically host symbiotic nitrogen-fixing
bacteria.
life cycle assessment: A comprehensive systems approach for measuring the inputs, outputs, and
potential environmental impacts of a product or service over its life cycle, including resource
extraction/generation, manufacturing/production, use, and end-of-life management.
life cycle greenhouse gas emissions: The aggregate quantity of greenhouse gas emissions
(including direct emissions and significant indirect emissions such as significant emissions from
land use changes), as determined by the EPA Administrator, related to the full fuel life cycle,
where the mass values for all greenhouse gases are adjusted to account for their relative global
warming potential. (See above for definition of "biofuel life cycle.")
milling residues (primary and secondary): Wood and bark residues produced in processing (or
milling) logs into lumber, plywood, paper, furniture, or other wood-based products.
mitigation: In the context of the environment, action to reduce adverse environmental impacts.
neat biofuel: See "B100"
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Appendix A
net energy balance: In the context of biofuel, refers to the energy content in the resulting
biofuel minus the total amount of energy used over the production and distribution process.
nitrogen fixation: The transformation of atmospheric nitrogen into nitrogen compounds that
growing plants can use. Nitrogen-fixing species, such as soybeans, can accomplish this process
directly.
nutrient loading: A process in which compounds from waste and fertilizers, such as nitrogen
and phosphorus, enter a body of water. This can happen, for example, when sewage is managed
poorly, when animal waste enters ground water, or when fertilizers from residential and
agricultural runoff wash into a stream, river, or lake.
oxygenated fuels: Fuels, typically gasoline, that have been blended with alcohols or ethers that
contain oxygen in order to reduce carbon monoxide and other emissions.
ozone: A form of oxygen consisting of three oxygen atoms. In the stratosphere (7 to 10 miles or
more above the Earth's surface), ozone is a natural form of oxygen that shields the Earth from
ultraviolet radiation. In the troposphere (the layer extending up 7 to 10 miles from the Earth's
surface), ozone is a widespread pollutant and major component of photochemical smog.
perennial grass: A species of grass that lives more than two years and typically has low nutrient
demand and diverse geographical growing range, and offers important soil and water
conservation benefits.
photobioreactor: A vessel or closed-cycle recirculation system containing some sort of
biological process that incorporates some type of light source. Often used to grow small
phototrophic organisms such as cyanobacteria, moss plants, or algae for biodiesel production.
renewable biomass: As defined by the 2007 Energy Independence and Security Act, renewable
biomass is any of the following:
• Planted crops and crop residue from agricultural land cleared before December
19, 2007, and actively managed or fallow on that date.
• Planted trees and tree residue from tree plantations cleared before December 19,
2007, and actively managed on that date.
• Animal waste material and byproducts.
• Slash and pre-commercial thinnings from non-federal forestlands that are neither
old-growth nor listed as critically imperiled or rare by a State Natural Heritage
program.
• Biomass cleared from the vicinity of buildings and other areas at risk of wildfire.
• Algae.
• Separated yard waste and food waste.
renewable fuel: A fuel produced from renewable biomass that is used to replace or reduce the
use of fossil fuel.
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Appendix A
Renewable Fuels Standard (RFS) program: An EPA program created under the Energy Policy
Act of 2005 that established the first renewable fuel volume mandate in the United States. The
original RFS program (RFS1) required 7.5 billion gallons of renewable fuel to be blended into
gasoline by 2012. (See below for RFS2.)
RFS2: The Renewable Fuels Standard program as revised in response to requirements of the
2007 Energy Independence and Security Act. RFS2 increased the volume of renewable fuel
required to be blended into transportation fuel to 36 billion gallons per year by 2022.
RFS2 Regulatory Impact Analysis (RIA): EPA's analysis of the impacts of the increase in
production, distribution, and use of the renewable fuels need to meet the RFS2 volumes
established by Congress in the 2007 Energy Independence and Security Act.
riparian forest buffer: An area of trees and shrubs adjacent to streams, lakes, ponds, and
wetlands that may reduce nutrient loading, soil erosion, and pesticide contamination by removing
soil particles and contaminants from overland water flow.
row crop: A crop planted in rows wide enough to allow cultivators between the rows. Examples
include corn, soybeans, peanuts, potatoes, sorghum, sugar beets, sunflowers, tobacco, vegetables,
and cotton.
sedimentation: Soil particles, clay, sand, or other materials settle out of a fluid suspension into
the bottom of a body of water.
short-rotation woody crop (SRWC): Fast-growing tree species grown on plantations and
harvested in cycles shorter than is typical of conventional wood products, generally between
three and 15 years. Examples include hybrid poplars (Populus spp.), willow (Salix spp.), and
eucalyptus.
soil erosion: The movement and loss of soil by the action of wind or water or a combination
thereof.
soil organic matter: Decomposed plant and animal material fully incorporated into the soil.
soil quality: The capacity of a specific kind of soil to function, within natural or managed
ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and
air quality, and support human health and habitation.
sugarcane bagasse: The fibrous material that remains after sugar is pressed from sugarcane.
sweet sorghum pulp: The bagasse or dry refuse left after the juice is extracted from sweet
sorghum stalks during the production of ethanol and other sweet sorghum products. The pulp is
usually treated as farm waste in plantations that grow sweet sorghum for biofuel production.
transesterification: In the context of biofuel, the chemical process that reacts an alcohol with
triglycerides in vegetable oils and animal fats to produce biodiesel and glycerin.
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Appendix A
turbidity: A cloudy condition in water due to suspended silt or organic matter.
vegetative reproduction: A form of asexual reproduction in plants by which new individuals
arise without the production of seeds or spores. It can occur naturally or be induced by
horticulturists.
water availability: In the context of this report, water availability refers to the amount of water
that can be appropriated from surface water sources (e.g., rivers, streams, lakes) or ground water
sources (e.g., aquifers) for consumptive uses.
water quality: Water quality is a measure of the suitability of water for a particular use based on
selected physical, chemical, and biological characteristics. It is most frequently measured by
characteristics of the water such as temperature, dissolved oxygen, and pollutant levels, which
are compared to numeric standards and guidelines to determine if the water is suitable for a
particular use.
wet milling: In the context of biofuel, a process for producing conventional corn starch ethanol
in which the corn is soaked in water or dilute acid to separate the grain into its component parts
(e.g., starch, protein, germ, oil, kernel fibers) before converting the starch to sugars that are then
fermented to ethanol.
woody biomass: Tree biomass thinned from dense stands or cultivated from fast-growing
plantations. This also includes small-diameter and low-value wood residue, such as tree limbs,
tops, needles, and bark, which are often byproducts of forest management activities.
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Appendix B
Appendix B
Summary of EPA Statutory Authorities
Having Potential Impact on the Production
and Use of Biofuels
B-l
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
I
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Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Clean Air Act (CAA) (http://www.epa.gov/air/caa/)
td
to
The CAA defines EPA's
responsibilities for protecting and
improving air quality and
stratospheric ozone. It requires EPA
to set national ambient air quality
standards (NAAQS) for widespread
pollutants from numerous and
diverse sources considered harmful
to public health and the
environment. EPA and states must
develop regulations to achieve and
maintain the NAAQS and to control
other pollutants.
Vehicles used for the
transportation of
feedstock may be subject
to an inspection and
maintenance program for
tailpipe emissions and
vehicle emission
standards for air quality.
A biofuel plant will need to obtain an air operating
permit for day-to-day facility operations. Based on
potential-to-emit, a facility may be required to
obtain a Title V Air Operating Permit. Operating
permits will be issued containing emission limits,
monitoring, and recordkeeping requirements.
Pre-construction permits will be required for initial
construction and for changes made to the plant.
There are two types of major pre-construction
permits under the New Source Review (NSR)
Program: Prevention of Significant Deterioration
permits and Nonattainment NSR permits. A minor
pre-construction permit would be required if major
NSR is not required.
A vehicle used to transport biofuels may be subject
to an inspection and maintenance program.
The CAA regulates the amount of
ethanol mixed in gasoline as part of
the reformulated gasoline program.
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Clean Water Act (CWA) (http://www.epa.gov/watertrain/cwa/)
The goal of the CWA is to restore
and maintain the chemical,
physical, and biological integrity of
the nation's waters.
Entities that discharge to waters of
the United States through point
sources (i.e., pipes, ditches,
concentrated animal feeding
operations), must obtain a National
Pollutant Discharge Elimination
System (NPDES) permit. These
entities include many municipal,
industrial, and construction-related
sources of stormwater.
States develop water quality
standards (WQS) that define the
goals for a water body by
designating its uses, setting criteria
to protect those uses, and
establishing provisions to protect
that water body. The CWA requires
states to identify waters not meeting
WQS and to develop Total
Maximum Daily Loads (TMDLs)
for those waters. TMDLs identify
point- and nonpoint-source loads
that can be discharged to a water
body and still meet WQS.
Agricultural stormwater
and irrigation returns
flows are exempted from
NPDES permit
requirements.
Under Section 319, EPA
provides grants to states
to address nonpoint
sources of pollution.
A biofuel production facility typically uses water for
cooling and also for washing the biofuel product to
remove impurities. The wastewater is discharged either
directly to a water body or indirectly to a municipal
wastewater treatment plant. Both are point-source
discharges, regardless whether the facility uses a septic
tank or treatment prior to discharge. Any discharge
into a water body by a point source must have an
NPDES permit prior to discharge. Permits may be
required for discharge to a municipal wastewater
treatment system, which could include pre-treatment
requirements. Land application of wastewater may be
covered by an NPDES permit if it is determined that
pollutants run off the application site to a waterway in
a discernible channel or pipe.
To minimize the impact of site runoff on water quality,
a NPDES stormwater permit must be obtained for
discharges to waters of the United States from any
construction activity that disturbs 1 acre or more of
land (including smaller sites that are part of a larger
common plan of development).
Management of emergency response
oil discharges must be reported to
the National Response Center if they
are in a quantity that "may be
harmful."
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
CWA: Section 404 Wetlands Program (www.epa.gov/owow/wetlands/laws/)
Section 404 addresses the
discharges of dredged or fill
material into waters of the United
States, including wetlands.
Permits are required for activities
such as expanded water resource
projects (including dams,
impoundments, and levees) and
altering or dredging a water of the
United States.
Most ongoing
agricultural maintenance
practices are exempt
from Section 404.
Generally, Section 404 requires a permit before these
materials may be placed in a U.S. water, such as a
wetland, stream, river, slough, lake, bay, etc., during
construction activities.
Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) (http://www.epa.gov/lawsregs/laws/cercla.html)
CERCLA provides a federal
"Superfund" to cleanup
uncontrolled or abandoned
hazardous waste sites as well as
accidents, spills, and other
emergency releases of pollutants
and contaminants into the
environment. Through CERCLA,
EPA was given authority to ensure
responsible parties' cooperation in
site cleanup. CERCLA also
regulates the property transfer of
these sites.
Requirements under CERCLA that may apply include:
• Reporting requirements for hazardous substances.
• Implementation and periodic revision of the National
Contingency Plan.
• Management by emergency response authorities and
responses to discharges of biofuels.
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td
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Emergency Planning and Community Right-to-Know ACT (EPCRA) (http://www.epa.gov/oecaagct/lcra.html)
The objective of the EPCRA is to:
(1) allow state and local planning
for chemical emergencies, (2)
provide for notification of
emergency releases of chemicals,
and (3) address communities' right-
to-know about toxic and hazardous
chemicals.
td
Section 302 requires any facility with regulated
chemicals (extremely hazardous substances) above
threshold planning quantities to notify the state
emergency response commission (SERC) and the local
emergency planning committee (LEPC). Section 304
requires the facility to report a release of an extremely
hazardous substance. Section 311 requires the facility
to have material safety data sheets (MSDSs) on site for
hazardous chemicals, as defined by the Occupational
Safety and Health Act, that exceed certain quantities
and to submit copies to its SERC, LEPC, and local fire
department. Section 312 establishes reporting for any
hazardous chemical or extremely hazardous chemical
that is stored at a facility in excess of the designated
threshold planning quantity. These reports are also
known as the Tier II hazardous chemical inventory
form. Section 313 requires owners or operators of
certain facilities that manufacture, process, or
otherwise use any listed toxic chemicals, or chemical
categories, in excess of threshold quantities to report
annually to EPA and to the state in which such
facilities are located.
Electric utilities are subject to
EPCRA Section 313, "Toxics
Release Inventory Reporting."
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (http://www.epa.gov/oecaagct/lfra.html)
The objective of FIFRA is to
provide federal control of pesticide
distribution, sale, and use.
EPA reviews and
registers pesticides for
specified uses and can
cancel the registration if
information shows
continued use would pose
unreasonable risk.
Consideration is given to
worker exposure
ecological exposure and
food-chain imports.
Hazardous Materials Transportation Act (Regulations Codified 49 CFR) (http://www.phmsa.dot.gov/hazmat/regs and
http://www.fmcsa.dot.gov/safety-security/hazmat/security-plan-guide.htm)
The Department of Transportation
regulations require procedures to be
put in place ensuring the safe
transport of hazardous materials.
Also, regulation HM-232 requires
companies to complete a written
security assessment and to develop
a security plan based on the
assessment.
Requirements are in place for shippers and carriers of
hazardous materials to prepare shipments for transport,
placard containers for easy identification of hazards,
and ensure the safe loading, unloading, and transport
of materials. HM-232 requires companies to complete
a written security assessment and to develop a security
plan based on the assessment.
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
National Environmental Policy Act (NEPA) (http://www.epa.gov/compliance/nepa/)
NEPA requires federal agencies to
integrate environmental values into
their decision-making processes by
considering the environmental
impacts of their proposed actions
and reasonable alternatives to those
actions. To meet NEPA
requirements in certain
circumstances, federal agencies
prepare a detailed statement known
as an Environmental Impact
Statement (EIS).
If federal money is being used to partially or entirely
finance the construction of a biofuel plant or any
associated facility, such as an access road or water
supply facility, then construction of the plant may be
subject to NEPA. NEPA requires federal agencies to
incorporate environmental considerations in their
planning and decision-making and to prepare a
detailed statement assessing the environmental impact
of activities and alternatives that significantly affect
the environment.
Oil Pollution Act (OP A) of 1990 (http://www.epa.gov/lawsregs/laws/opa.html)
The OPA of 1990 streamlined and
strengthened EPA's ability to
prevent and respond to catastrophic
oil spills. A trust fund financed by a
tax on oil is available to clean up
spills when the responsible party is
incapable or unwilling to do so. The
OPA requires oil storage facilities
and vessels to submit to the federal
government plans detailing how
they will respond to large
discharges.
Provides that the responsible party for a vessel or
facility from which oil is discharged, or which poses a
substantial threat of a discharge, is liable for: (1)
certain specified damages resulting from the
discharged oil; and (2) removal costs incurred in a
manner consistent with the National Contingency Plan.
Provides for spill contingency plans and mandates
development of response plans for worst case
discharge; provides requirements for spill removal
equipment. Oil Spill Plans must be in place before
operation at facilities that could spill oil to navigable
waters.
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
I
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Cd
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Renewable Fuel Standard (RFS) (http://www.epa.gov/otaq/fuels/renewablefuels/index.htm)
The RFS program was created
under the Energy Policy Act
(EPAct) of 2005, and established
the first renewable fuel volume
mandate in the United States. As
required under EPAct, the original
RFS program (RFS1) required 7.5
billion gallons of renewable fuel to
be blended into gasoline by 2012.
Under the Energy Independence
and Security Act (EISA) of 2007,
the RFS program was expanded.
EISA also required EPA to apply
life cycle greenhouse gas (GHG)
performance threshold standards.
The GHG requirement is that the
life cycle GHG emissions of a
qualifying renewable fuel must be
less than the life cycle GHG
emissions of the 2005 baseline
average gasoline or diesel fuel that
it replaces. Four different levels of
reductions are required for the four
different renewable fuel standards:
Renewable Fuel (20 percent);
Advanced Biofuel (50 percent);
Biomass-based Diesel (50 percent);
and Cellulosic Biofuel (60 percent).
If a facility produces 10,000 gallons or more of
renewable fuel per year, it may participate in the RFS
program, though it is not required to do so. A facility
that chooses to participate in the RFS program must
satisfy the following criteria:
• Register
• Generate renewable identification
• Transfer renewable identification numbers with fuel
• Provide product transfer documents
• Follow blending requirements
• Follow exporting requirements
• Follow non-road use of fuel
• Attest engagements
• Keep records for five years
• Report quarterly
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Resource Conservation and Recovery Act (RCRA) (http://www.epa.gov/lawsregs/laws/rcra.html)
RCRA gives EPA the authority to
control hazardous waste generation,
transportation, treatment, storage,
and disposal of hazardous waste.
Any facility that handles hazardous
waste must obtain an operating
permit from the state agency or
EPA. RCRA regulates USTs.
Regulatory issues related to solid and hazardous waste
generated by biofuel production include:
• New regulations on storage and transport of fuel
related to expanded use of biofuels.
• New concerns related to assessing compatibility of
fuel storage systems, managing water in storage
tanks, protecting against corrosiveness and
conductivity, managing methane formation, and
detecting, preventing and responding to storage tank
and pipe leaks and spills.
• Management of emergency response authorities and
responses to biofuel spills.
UST leak detection and prevention
are required.
Safe Drinking Water Act (SDWA) (http://www.epa.gov/ogwdw/sdwa/)
SDWA is the federal law that
protects the safety of water
distributed by public water systems.
Under SDWA, EPA has National
Primary Drinking Water
Regulations for more than 90
contaminants and rules regarding
monitoring of treated drinking
water as well as reporting and
public notification.
There are a number of
threats to drinking water:
anthropogenic chemicals
including pesticides and
improperly disposed
chemicals, animal wastes,
and naturally occurring
substances. A primary
impact to drinking water
is nitrate pollution from
row crops.
Wastewater from biofuel production facilities or corn
starch ethanol facilities and leaking biofuel storage
tanks can contaminate surface and ground drinking
water resources, requiring treatment under SDWA.
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Safe Drinking Water Act: Underground Injection Control (UIC) Program (http://www.epa.gov/safewater/uic/)
The UIC program protects
underground sources of drinking
water by regulating the
construction, operation, permitting,
and closure of injection wells that
place fluids underground for
storage or disposal.
Agriculture drainage
wells are Class V UIC
wells. They are primarily
regulated under state law.
A biofuels plant is subject to the requirements of the
UIC Program if any of the following apply:
• It is disposing of stormwater, cooling water, or
industrial or other fluids into the subsurface via an
injection well.
• It has an onsite sanitary waste disposal system (e.g.,
aseptic system) that serves or has the capacity to
serve 20 or more persons.
• It has an onsite sanitary waste disposal system that is
receiving other than a solely sanitary waste stream
regardless of its capacity.
• It is undergoing a remediation process where fluids
are being introduced into the subsurface via an
injection well to facilitate or enhance the cleanup.
Spill Prevention, Control and Countermeasure (SPCC) and Facility Response Plans (FRP) (http://www.epa.gov/oem/content/spcc/index.htm)
The SPCC rule includes
requirements for oil spill
prevention, preparedness, and
response to prevent oil discharges
to navigable waters and adjoining
shorelines. The rule requires
specific facilities to prepare,
amend, and implement SPCC
Plans. The SPCC rule is part of the
Oil Pollution Prevention regulation,
which also includes the FRP rule.
The SPCC program
requires certain farms
(e.g., those that store oil
and could reasonably be
expected to discharge oil
to waters of the United
States) to prepare and
implement SPCC Plans.
A biofuel facility is subject to this regulation if the
following apply:
• It is non-transportation-related.
• It has a total above-ground oil storage capacity
greater than 1,320 gallons or a completely buried oil
storage capacity greater than 42,000 gallons.
• There is a reasonable expectation of an oil discharge
into or upon navigable waters of the United States
or adjoining shorelines.
• Secondary containment cannot be provided for all
regulated oil storage tanks.
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Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Life Cycle
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Toxic Substances Control Act (TSCA) (http://www.epa.gov/lawsregs/laws/tsca.html)
TSCA gives EPA broad authority to
identify and control chemical
substances that may pose a threat to
human health or the environment.
EPA's Office of Pollution
Prevention and Toxics operates
both the New Chemicals Program
and the Biotechnology Program
under Section 5 of TSCA. Both
programs were established to help
manage the potential risk from
chemical substances and genetically
engineered (intergeneric)
microorganisms new to the
marketplace or applied in
significant new uses. Additional
sections of TSCA give EPA the
broad authority to issue toxicity
testing orders or to regulate the use
of any existing chemicals that pose
unreasonable risk.
Notification and review
of new intergeneric
genetically engineered
microbes (e.g., bacteria,
fungi and algae) used to
produce biofuel
feedstocks.
Mandatory notification and approval for new
chemicals and new biological products, before
manufacture and commercial use. New uses of
chemicals are subject to review for potential
environmental hazards under the Significant New Use
Notification process. As a result of the review process,
health and environmental effects testing of existing or
new chemicals that pose unreasonable risk may be
required. EPA may also restrict use and handling of
chemicals or biological products as a result of their
review.
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Appendix C
Appendix C
Conceptual Models
c-i
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Appendix C
As described in this report, the activities associated with cultivation of biofuel feedstocks
and their conversion to fuel result in a complex set of inter-related environmental impacts.
Conceptual models provide a useful tool to describe, understand, and communicate the complex
pathways by which these activities lead to impacts. As noted in Chapter 7, EPA anticipates
developing and using conceptual models as an important tool for the assessment in its next
Report to Congress. The conceptual models presented in this appendix lay a foundation for this
future effort. Figures C-l to C-7 present conceptual models for feedstock cultivation and harvest.
Figures C-8 and C-9 present models for biofuel production and distribution. (Note that models
are not included for end use of biofuel.) These early renditions graphically present the
environmental effects most commonly identified in current peer-reviewed literature; while
comprehensive, they do not attempt to include all possible effects.
Terms and Abbreviations Used in the Conceptual Models
From the Legend
• biotic response: Response of living parts of terrestrial or aquatic ecosystems, in terms of either number of
species or numbers of individuals of a particular species
• ecosystem service: Direct or indirect contribution of the environment to human well-being
• environmental parameter: A measureable attribute of the environment
From the Diagrams
• aquatic life use support: A beneficial use designation in which the water body provides suitable habitat for
survival and reproduction of desirable fish, shellfish, and other aquatic organisms (this is a synthetic quality
made up of many different environmental parameters)
• BOD: biological oxygen demand
• contamination: Release of nutrients or pesticides used in feedstock production to waterways or bodies of
water
• PM: participate matter
• T &E species: threatened and endangered species
• VOC: volatile organic compound
Feedstock Production
Figures C-l to C-7 present seven models for six feedstocks covered in this report: corn
starch, soybeans, corn stover, perennial grass, woody biomass (short-rotation woody crops and
forest thinning/residue removal), and algae production.
Different pathways are introduced at the tops of several of these feedstock models. These
pathways were selected because (1) they will likely be pursued in combination in order to grow
enough feedstock to meet RFS2 2022 biofuel requirements (see Chapter 2 for a description of
requirements) and (2) they result in different environmental impacts.
Arrows in the impact boxes (below the initial row of activities) depict whether the
impacts are negative or positive. The number(s) by each arrow designate the pathway to which
the arrows refer. A few pathways can have both negative and positive impacts (e.g., corn starch
cultivation could result in increased or decreased use of ground and surface water). Dotted
borders denote impacts that have a relatively large degree of uncertainty due to a lack of
C-2
-------
Appendix C
information. Dotted boxes without arrows depict highly uncertain impacts that nonetheless are
described in the literature.
Fuel Production and Distribution
Figures C-8 and C-9 present conceptual models for production and distribution of the two
biofuels covered in this report: ethanol and biodiesel.
Ethanol Production
Figure C-8 shows the activities and impacts associated with production and distribution
of ethanol from both starch (i.e., corn grain) and cellulosic feedstocks, including corn stover,
perennial grasses, and woody biomass. A single model is provided for these four types of
feedstocks because their impacts and associated uncertainty are largely similar, with a few
exceptions (e.g., water use will likely be slightly higher for cellulose conversion).
As depicted in the upper left of Figure C-8, conversion of starch to ethanol consists of
several sequential steps, including milling, hydrolysis, and fermentation. There currently are two
distinct alternatives for converting cellulosic feedstock into ethanol: (1) biochemical conversion
(which is preceded by a catalysis step to separate cellulose and hemicellulose from their tightly
bound state with lignin), and (2) thermochemical conversion. These alternatives involve slightly
different chemical processes and byproducts. As with Figures C-l to C-7, a dotted border is used
to denote impacts with relatively large uncertainty due to a lack of information.
Biodiesel Production
Figure C-9 shows the activities and impacts associated with production of biodiesel from
soybeans and algae. Several techniques may be used to convert plant oils into biodiesel,
including hydrogenation, catalytic cracking, and transesterification. All these processes produce
biodiesel, with glycerin as a byproduct.
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Figure C-l: Pathways for Potential Environmental Impacts of Corn Starch Feedstock Cultivation
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Figure C-2: Pathways for Potential Environmental Impacts of Soybean Feedstock Cultivation
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Appendix C
Figure C-3: Pathways for Potential Environmental Impacts of Corn Stover Feedstock Cultivation*
*Corn stover is a waste product of corn starch cultivation. The impacts of corn cultivation are shown in Figure C-1. Figure C-3 highlights the environmental
impacts of stover removal above and beyond those impacts attributable to corn grain production.
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Figure C-4: Pathways for Potential Environmental Impacts of Perennial Grass Feedstock Cultivation
f
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managed, non-federal
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Figure C-5: Pathways for Potential Environmental Impacts of Short-Rotation Woody Crop Feedstock Cultivation
*These particular land use changes may not currently be allowable under RFS2.
I
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N
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Figure C-6: Pathways for Potential Environmental Impacts of Forest Thinning and Residue Removal
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Figure C-7: Potential Environmental Impacts of Algae Feedstock Production
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/ feedstock/
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v ;
Figure C-8: Potential Environmental Impacts of Producing and Distributing Conventional and Cellulosic Ethanol
(Impacts of Fuel Use Not Included)
f
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/Soybean/algae/ >| oil extraction I 5\conversion of oil to biodiese
/ feedstock / | | |
LEGEND
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I
6
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Figure C-9: Potential Environmental Impacts of Producing and Distributing Biodiesel
(Impacts of Fuel Use Not Included)
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