oEPA
United States
Environmental Protection
Agency
EPA/600/R-10/183A
January 2011
External Review Draft
DRAFT
DO NOT CITE OR QUOTE
Biofuels and the Environment:
First Triennial Report to Congress
NOTICE
THIS DOCUMENT IS A PRELIMINARY DRAFT. It has not been formally released by the
U.S. Environmental Protection Agency and should not at this stage be construed to represent
Agency policy. It is being circulated for comment on its technical accuracy and policy
implications.
National Center for Environmental Assessment
Office of Research and Development
U.S. Environmental Protection Agency
Washington, DC
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DISCLAIMER
This document is distributed solely for the purpose of pre-dissemination peer review
under applicable information quality guidelines. It has not been formally disseminated by EPA.
It does not represent and should not be construed to represent any Agency determination or
policy. Mention of trade names or commercial products does not constitute endorsement or
recommendation of use.
This document is a draft for review purposes only and does not constitute Agency policy.
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Executive Summary
Executive Summary
This report is the first of the U.S. Environmental 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.
EISA Section 204 calls for EPA to report to Congress 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. This report reviews impacts and mitigation tools across the
entire biofuel supply chain, including feedstock production and logistics, and biofuel production,
distribution, and use. The report focuses on:
• Six feedstocks: The two most predominantly used {corn starch and soybeans),
and four others {corn stover, perennial grasses, woody biomass, and algae) that
represent a range of feedstocks currently under development. Because the RFS2
limits the amount of corn starch-derived biofuel that counts toward the volume
requirement in 2022 to 15 billion gallons, an increased reliance on other
feedstocks is predicted.
• Two biofuels: Ethanol (both conventional and cellulosic) and biomass-based
diesel, because they are the most commercially viable in 2010 and/or projected to
be the most commercially available by 2022.
This first report represents peer-reviewed information available through July 2010 and
reflects the current uncertainty about biofuel production and use. Quantitative assessments are
presented, where possible, however, in most cases only qualitative assessments were feasible due
to uncertainties and the lack of data and analyses in the peer-reviewed literature. Conclusions,
which do not account for existing or potential future mitigation measures or regulations, include:
• Life Cycle Assessment. Some segments of the biofuel life cycle result in
greenhouse gas (GHG) emissions; however, as noted in EPA's RFS2 Regulatory
Impact Analysis, when the entire biofuel life cycle is considered, the EISA-
mandated revisions to the RFS2 program are expected to achieve a 138-million
metric ton reduction in carbon dioxide-equivalent emissions by 2022 compared to
continued reliance on petroleum-based fuels.
• Water Quality. Ground and surface water quality can be impacted by erosion and
runoff of fertilizers and pesticides when feedstocks, particularly row crops such as
corn, are cultivated for biofuel; through pollutants in the wastewater discharged
from biofuel production facilities; and from leaks and spills during fuel transport.
This document is a draft for review purposes only and does not constitute Agency policy.
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Executive Summary
• Water Quantity. Effects of feedstock production on water availability vary
greatly by feedstock, processes used to produce the feedstock, and location.
Depending on location, the amount of water required to grow corn and soybean
for biofuel can be far greater than that required to grow perennial grasses, woody
biomass, and algae. Water used by biofuel production facilities is modest
compared to that required to produce biofuel feedstocks, and impacts depend on
the location of the facility in relation to water resources.
• Soil Quality. Increased cultivation of biofuel feedstocks is likely to affect soil
quality in various ways, depending on the feedstock. Some feedstocks may
contribute to detrimental effects, including increased soil erosion, decreased soil
organic matter content, increased soil GHG emissions, and increased nitrogen and
phosphorus losses to ground and surface waters. Other feedstocks may contribute
to advantageous effects such as increased soil carbon and reduced erosion.
• Air Quality. Air quality may be impacted by pollutants from feedstock
production, such as farm equipment emissions and soil/dust particles made
airborne during field tillage and fertilizer application; by emissions from
combustion equipment used for energy production at biofuel production facilities;
and by evaporative and tailpipe emissions from combustion in vehicles.
• Ecosystem. Increased cultivation of feedstocks for biofuel could significantly
affect biodiversity through habitat alteration when uncultivated land is put into
production; from exposure of flora and fauna to pesticides; or through
sedimentation and eutrophication in water bodies resulting from soil erosion and
nutrient runoff, respectively. Invasiveness potential of cultivated feedstocks is
also a concern, but varies by feedstock.
• International. Increases in U.S. biofuel production and consumption volumes
will affect many different countries as trade patterns and prices adjust in response
to global supply and demand. This will result in land use change and effects on air
quality, water quality, and biodiversity. Direct and indirect land use changes will
likely occur across the globe as the U.S. and other biofuel feedstock-producing
countries alter their agricultural sectors to allow for greater biofuel production.
Many locations where biofuel production is growing, such as Indonesia,
Malaysia, and Brazil, are also areas of high biodiversity value. Depending where
biofuel feedstock production occurs, and to what extent the level of production
increases with time, impacts to biodiversity could be significant.
Most activities, processes, and products associated with the biofuel supply chain are
already regulated, subject to limitations, or mitigated through various approaches. To further
address adverse impacts, EPA recommends:
• Developing and evaluating Environmental Life Cycle Assessments for biofuels.
• Ensuring the success of current and future environmental biofuel research through
improved cooperation and sustained support.
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Executive Summary
• Improving the ability of federal agencies (within their existing authorities) to
develop and implement best management and conservation practices and policies
that will avoid or mitigate negative environmental effects from biofuel production
and use.
• Engaging the international scientific community in cooperative efforts to identify
and implement sustainable biofuel practices that minimize environmental impact.
Because biofuel impacts cross many topics and Agency responsibilities, EPA likely will
address these recommendations through continued and strengthened cooperation with federal
agencies and international partners, including the U.S. Departments of Agriculture and Energy.
This document is a draft for review purposes only and does not constitute Agency policy.
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Table of Contents
Table of Contents
Page
Executive Summary i
1. Introduction 1-1
2. Background and Approach 2-1
2.1 EISA and RFS2 Requirements for Biofuel Production and Use 2-1
2.2 Projected Fuel and Feedstock Use to Meet Required RFS2 Targets through
2022 2-2
2.3 Assessment of the Environmental and Resource Conservation Impacts of
Biofuels 2-4
2.3.1 Approach 2-4
2.3.2 Biofuel Supply Chain 2-5
2.3.3 Feedstocks and Fuels Discussed in This Report 2-5
2.3.4 Impacts Discussed in This Report 2-6
2.4 Regulatory Authority Relevant to Biofuel Environmental Impacts 2-9
3. Environment at Impacts of Specific Feedstocks 3-1
3.1 Introduction 3-1
3.2 Row Crops (Corn, Corn Stover, Soybeans) 3-2
3.2.1 Introduction 3-2
3.2.1.1 Current and Projected Cultivation 3-3
3.2.1.2 Overview of Environmental Impacts 3-6
3.2.2 Water Quality 3-9
3.2.2.1 Nutrient Loading 3-10
3.2.2.2 Sediment 3-15
3.2.2.3 Pesticides 3-16
3.2.2.4 Pathogens and Biological Contaminants 3-17
3.2.3 Water Quantity 3-18
3.2.3.1 WaterUse 3-18
3.2.3.2 Water Availability 3-19
3.2.4 Soil Quality 3-20
3.2.4.1 Soil Erosion 3-20
3.2.4.2 Soil Organic Matter 3-21
3.2.5 Air Quality 3-22
3.2.5.1 Cultivation and Harvesting 3-22
3.2.5.2 Fertilizers and Pesticides 3-23
3.2.6 Ecosystem Impacts 3-23
3.2.6.1 Eutrophication, Erosion, and Biodiversity Loss 3-23
3.2.6.2 Invasive Plants 3-25
3.2.7 Assessment 3-25
3.2.7.1 Key Uncertainties and Unknowns 3-26
3.3 Perennial Grasses 3-28
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Table of Contents
TABLE OF CONTENTS (Continued)
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3.3.1 Introducti on 3-28
3.3.1.1 Current and Proj ected Cultivation 3-30
3.3.1.2 Overview of Environmental Impacts 3-31
3.3.2 Water Quality 3-31
3.3.2.1 Nutrient Loading 3-32
3.3.2.2 Sediment 3-32
3.3.2.3 Pesticides 3-33
3.3.2.4 Pathogens and Biological Contaminants 3-33
3.3.3 Water Quantity 3-33
3.3.3.1 WaterUse 3-33
3.3.3.2 Water Availability 3-34
3.3.4 Soil Quality 3-34
3.3.4.1 Soil Erosion 3-34
3.3.4.2 Soil Organic Matter 3-34
3.3.5 Air Quality 3-35
3.3.6 Ecosystem Impacts 3-36
3.3.6.1 Biodiversity 3-36
3.3.6.2 Invasive Plants 3-36
3.3.7 Assessment 3-38
3.3.7.1 Key Uncertainties and Unknowns 3-38
3.4 Woody Biomass 3-39
3.4.1 Introduction 3-39
3.4.1.1 Current and Projected Production Areas 3-40
3.4.1.2 Overview of Environmental Impacts 3-41
3.4.2 Water Quality 3-41
3.4.2.1 Nutrients 3-42
3.4.2.2 Sediment 3-43
3.4.2.3 Pesticides 3-43
3.4.3 W ater Quantity 3-43
3.4.3.1 WaterUse 3-43
3.4.3.2 Water Availability 3-44
3.4.4 Soil Quality 3-44
3.4.4.1 Soil Erosion 3-44
3.4.4.2 Soil Organic Matter 3-44
3.4.4.3 Soil Nutrients 3-45
3.4.5 Air Quality 3-45
3.4.6 Ecosystem Impacts 3-46
3.4.6.1 Biodiversity 3-46
3.4.6.2 Invasive Plants 3-46
3.4.7 Assessment 3-47
3.4.7.1 Key Uncertainties and Unknowns 3-47
3.5 Algae 3-48
3.5.1 Introduction 3-48
3.5.1.1 Current and Proj ected Cultivation 3 -49
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TABLE OF CONTENTS (Continued)
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3.5.1.2 Overview of Environmental Impacts 3-49
3.5.2 Water Quality 3-49
3.5.3 Water Quantity 3-50
3.5.3.1 WaterUse 3-50
3.5.3.2 Water Availability 3-50
3.5.4 Soil Quality 3-51
3.5.5 Air Quality 3-51
3.5.6 Ecosystem Impacts 3-51
3.5.6.1 Biodiversity 3-51
3.5.6.2 Invasive Algae 3-52
3.5.7 Assessment 3-52
3.5.7.1 Current and Future Impacts 3-52
3.5.7.2 Key Uncertainties and Unknowns 3-53
3.6 Waste-Based Feedstocks 3-54
3.6.1 Introduction 3-54
3.6.2 Municipal Solid Waste 3-54
3.6.3 Other Wastes 3-55
3.6.4 Environmental Impacts of Waste-Based Biofuel 3-55
3.7 Summary of Feedstock-Dependent Impacts on Specialized Habitats 3-56
3.7.1 Forests 3-56
3.7.2 Grasslands 3-57
3.7.3 Impacts on Wetlands 3-58
3.8 Genetically Engineered Feedstocks 3-59
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
4.2.1.1 Ethanol 4-2
4.2.1.2 Biodiesel 4-2
4.3 Biofuel Production 4-3
4.3.1 Biofuel Conversion Processes 4-3
4.3.1.1 Ethanol 4-3
4.3.1.2 Biodiesel 4-4
4.3.2 Air Quality 4-5
4.3.2.1 Ethanol 4-7
4.3.2.2 Biodiesel 4-7
4.3.2.3 Greenhouse Gases 4-7
4.3.3 Water Quality and Availability 4-9
4.3.3.1 Ethanol 4-10
4.3.3.2 Distillers Grain with Solubles 4-11
4.3.3.3 Biodiesel 4-12
4.3.4 Impacts from Solid Waste Generation 4-13
4.4 Biofuel Distribution 4-13
This document is a draft for review purposes only and does not constitute Agency policy.
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TABLE OF CONTENTS (Continued)
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4.4.1 Air Quality 4-13
4.4.1.1 Ethanol 4-13
4.4.1.2 Biodiesel 4-14
4.4.2 Water Quality 4-14
4.4.2.1 Ethanol 4-15
4.4.2.2 Biodiesel 4-16
4.5 Biofuel End Use 4-16
4.5.1 Air Quality 4-17
4.5.1.1 Ethanol 4-17
4.5.1.2 Biodiesel 4-17
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
5.4 Other Environmental Impacts 5-10
5.5 Concluding Remarks 5-12
6. Conclusions and Recommendations 6-1
6.1 Conclusions 6-1
6.1.1 Emissions Reduction 6-1
6.1.2 Feedstock Production 6-1
6.1.2.1 Overview 6-1
6.1.2.2 Conclusions 6-3
6.1.3 Biofuel Production, Transport, and Storage 6-4
6.1.3.1 Overview 6-4
6.1.3.2 Biofuel Transport and Storage 6-7
6.1.4 Biofuel End Use 6-7
6.1.5 International Considerations 6-7
6.2 Recommendations 6-8
6.2.1 Comprehensive Environmental Assessment 6-8
6.2.2 Coordinated Research 6-8
6.2.3 Mitigation of Impacts from Feedstock Production 6-9
6.2.4 International Cooperation to Implement Sustainable Biofuel
Practices 6-9
7. Assessing Environmental Impacts from Biofuels: 2013 to 2022 7-1
7.1 Introduction 7-1
7.2 Components of the 2013 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 7-2
7.2.4 Conceptual Model s 7-3
7.2.5 Monitoring, Measures, and Indicators 7-3
7.2.6 Scenarios 7-6
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TABLE OF CONTENTS (Continued)
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7.2.7 Other Components 7-8
8. References 8-1
Appendix A: GLOSSARY AND ACRONYMS A-l
Appendix B: SUMMARY OF SELECTED STATUTORY AUTHORITIES HAVING
POTENTIAL IMPACT ON THE PRODUCTION
AND USE 01 BIOFUELS B-l
Appendix C: BASIS FOR FIGURES 6-1, 6-2, AND 7-3 C-l
Appendix D: CONCEPTUAL MODELS D-l
This document is a draft for review purposes only and does not constitute Agency policy.
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List of Tables
186 LIST OF TABLES
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188 Page
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190 Table 2-1: RFS2 Renewable Fuel Requirements (billion gallons per year) 2-2
191 Table 2-2: Overview of Environmental and Resource Conservation Impacts Addressed in
192 This Report 2-7
193 Table 2-3: Overview of Environmental and Resource Conservation Impacts on Specific
194 Ecosystems Addressed in This Report 2-8
195 Table 3-1: Primary Fuels and Feedstocks Discussed in this Report 3-2
196 Table 3-2: Impacts Associated with Biofuel Feedstock Production (Corn Starch, Corn
197 Stover, and Soybean) 3-7
198 Table 3-3: Comparison of Agricultural Intensity Metrics for Perennial Grass and
199 Conventional Crops 3-32
200 Table 3-4: Comparison of Agricultural Intensity Metrics for Short-Rotation Woody Crops
201 and Conventional Crops 3-42
202 Table 3-5: Overview of Impacts on Forests from Different Types of Biofuel Feedstocks 3-57
203 Table 3-6: Overview of Impacts on Grasslands from Different Types of Biofuel
204 F eedstocks 3-58
205 Table 3-7: Overview of Impacts on Wetlands from Different Types of Biofuel Feedstocks.... 3-58
206 Table 4-1. 2009 Summary of Inputs to U.S. Biodiesel Production 4-4
207 Table 4-2. Lifecycle GHG Thresholds Specified in EISA (percent reduction from 2005
208 baseline) 4-8
209 Table 5-1: Top Fuel Ethanol-Producing Countries from 2005 to 2009 (All figures are in
210 millions of gallons) 5-2
211 Table 5-2: RFS2 RIA Projected Imports and Corn Ethanol Production, 2011-2022 5-3
212 Table 5-3: Historical U.S. Domestic Ethanol Production and Imports 5-4
213 Table 5-4: 2008-2009 Brazilian Ethanol Exports by Country of Destination 5-4
214 Table 5-5: 2008 U.S. Biodiesel Balance of Trade 5-6
215 Table 5-6: Changes in International Crop Area Harvested by Renewable Fuel Anticipated
216 to Result from EISA Requirements by 2022 5-8
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List of Figures
217 LIST OF FIGURES
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221 Figure 2-1: Projected Renewable Fuel Volumes to Meet RFS2 Targets 2-3
222 Figure 2-2: Examples of Feedstocks Available for Biofuel Production 2-4
223 Figure 2-3: Five Stages of the Biofuel Supply Chain 2-5
224 Figure 2-4: Environmental and Resource Conservation Issues Addressed in this Report 2-6
225 Figure 3-1: U.S. Corn Production 3-2
226 Figure 3-2: Planted Corn Acres by County, for Selected States (2009) 3-3
227 Figure 3-3: Planted Soybean Acres by County (2009) 3-6
228 Figure 3-4: Change in Number of U.S. Coastal Areas Experiencing Hypoxia from 1960
229 to 2008 3-13
230 Figure 3-5: Generalized Map of Potential Rain-fed Feedstock Crops in the Conterminous
231 United States Based on Field Plots and Soil, Prevailing Temperature, and Rainfall
232 Patterns 3-31
233 Figure 3-6: Estimated Forest Residues by County 3-41
234 Figure 4-1: Sources of Criteria Air Pollutant and Toxics Emissions Associated with
235 Production and Use of Biofuel 4-1
236 Figure 5-1: Biofuel Production Map 5-1
237 Figure 5-2: Historic U.S. Ethanol Export Volumes and Destinations 5-5
238 Figure 5-3: Change in U.S. Exports by Crop Anticipated to Result from EISA
239 Requirements by 2022 (tons per 1,000 gallons of renewable fuel) 5-7
240 Figure 5-4: International Land Use Change GHG Emissions by Renewable Fuel
241 Anticipated to Result from EISA Requirements by 2022 (kgC02e/mmBTU) 5-8
242 Figure 5-5: Harvested Crop Area Changes by Region Anticipated to Result from EISA
243 Requirements by 2022, 2022 (ha / billion BTU) 5-9
244 Figure 5-6: Pasture Area Changes in Brazil by Renewable Fuel Anticipated to Result
245 from EISA Requirements by 2022 (ha / billion BTU) 5-10
246 Figure 6-1: Maximum Potential Range of Environmental Impacts (on a Per Unit Area
247 Basis) Resulting from Cultivation and Harvesting of the Six Biofuel Feedstocks
248 Considered in This Report 6-2
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List of Figures
249 Figure 6-2: Maximum Potential Range of Environmental Impacts (on a Per Unit Volume
250 Basis) Resulting from Ethanol and Biodiesel Production, Transport, and Storage 6-6
251 Figure 7-1: Conceptual Diagram of the Environmental Impacts of Biofuel Feedstock
252 Production 7-4
253 Figure 7-2: Conceptual Diagram of the Environmental Impacts of Biofuel Production and
254 Use 7-5
255 Figure 7-3: Cumulative Domestic Environmental Impacts of All Steps in the Biofuel
256 Supply Chain System under Three Scenarios in 2022 7-7
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Chapter 1: Introduction
1. Introduction
In December 2007, Congress enacted the Energy Independence and Security Act (Public
Law 110-140) (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. Accordingly, EISA requires the U.S. Environmental Protection Agency (EPA) to revise
the Renewable Fuel Standard (RFS) program, created under the 2005 Energy Policy Act,a to
increase the volume of renewable fuelb 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). Meeting RFS2 in 2022 will result in biofuels
making up an estimated 7 percent of fuels (by volume) used for transportation (U.S. EPA,
2010a). 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
Actc on the following:
1. Environmental issues, including air quality, effects on hypoxia, pesticides, d
sediment, nutrient and pathogen levels in waters, acreage andfunction 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.
4. .... The report shall include the annual volume of imported renewable fuels and
feedstocks for renewable fuels, and the environmental impacts outside the United
a 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.
b To be considered "renewable," fuels produced by biorefineries 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.
0 EISA 2007 amended Section 21 l(o) of the Clean Air Act to include the definitions and requirements of RFS2.
d Pesticides include antimicrobials, fungicides, herbicides, insecticides, and rodenticides.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 1: Introduction
States of producing such fuels andfeedstocks. The report required by this
subsection shall include recommendations for actions to address any adverse
impacts found.
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 mitigation tools
to reduce these impacts, across major components of the biofuel supply chain: feedstock
production, feedstock logistics, biofuel production, biofuel distribution, and biofuel use.
This report emphasizes domestic impacts; however, the substantial market created for
biofuels by the U.S, Brazil, and other countries has important global implications. For example,
countries that produce feedstocks, now or in the future, which are converted to biofuels that
qualify for use in the U.S. will experience direct impacts; other countries 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 from the U.S Departments of Agriculture and Energy, with whom EPA consulted during
development of this report. Quantitative assessments are presented, where possible, using 2010
or the most recently available data; however, in most cases only qualitative assessments were
feasible due to uncertainties and lack of data and analyses in the peer-reviewed literature. 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.
This document is a draft for review purposes only and does not constitute Agency policy.
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2. Background and Approach
2.1 EISA and RFS2 Requirements for Biofuel Production and Use
RFS2 (the Renewable Fuel Standard as amended by the Energy Independence and
Security Act [EISA]) establishes new specific annual volume standards for four categories of
renewable fuels that must be used in transportation fuel5: cellulosic biofuel, biomass-based
diesel, advanced biofuel, and total renewable fuel (see 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
that EPA conducted as part of its Regulatory Impact Analysis [RIA] during the final RFS2
rulemaking).
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 each November to set the volume standards for the following year based
in part on information provided by the Energy Information Administration (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
o
standard. 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. (This contrasts with the original RFS [RFS1], which did not provide credit for renewable fuel
blended into non-road 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. 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.
This document is a draft for review purposes only and does not constitute Agency policy.
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Table 2-1: RFS2 Renewable Fuel Requirements (billion gallons per year)a b
Year
Renewable Fuel
Conventional
Biofuel
Advanced Biofuel
Total
Renewable Fuel
Cellulosic Biofuel
Biomass-Based
Diesel
Advanced Biofuel0
2008
9.0
n/a
n/a
n/a
9.0
2009
10.5
n/a
0.5
0.6
11.1
2010
12.0
0.1 d
0.65
0.95
12.95
2011
12.6
0.25
0.80
1.35
13.95
2012
13.2
0.5
1.0
2.0
15.2
2013
13.8
1.0
TBD e
2.75
16.55
2014
14.4
1.75
TBD e
3.75
18.15
2015
15.0
3.0
TBD e
5.5
20.5
2016
15.0
4.25
TBD e
7.25
22.25
2017
15.0
5.5
TBD e
9.0
24.0
2018
15.0
7.0
TBD e
11.0
26.0
2019
15.0
8.5
TBD e
13.0
28.0
2020
15.0
10.5
TBD e
15.0
30.0
2021
15.0
13.5
TBD e
18.0
33.0
2022
15.0
16.0
TBD e
21.0
36.0
a - The requirements for cellulosic biofuel, bioinass-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,
c - 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 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, 2010b.
2.2 Projected Fuel and Feedstock Use to Meet Required RFS2 Targets through 2022
Figure 2-1 summarizes the fuel types and volumes projected to meet the required targets
through 2022, as estimated in the RFS2 Regulatory Impact Analysis. Although actual volumes
and feedstocks will likely be different, EPA believes the projections are within the range of
expected outcomes when the standards are met (U.S. EPA, 2010b).
This document is a draft for review purposes only and does not constitute Agency policy.
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35
30
25
Total Biofuel
20
Corn Ethanol
15
10
Cell ulosic Biofuel
5
Other Advanced Biofuel
Biomass-based Diesel
0
2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022
Source: U.S. EPA, 2010b.
Figure 2-1: Projected 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; El A, 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 (Figure 2-2) (U.S. EPA, 2010b). Present research is focused on
improving technologies to convert different feedstocks to biofuels in an economically viable
manner, and determining sustainable biofuel production methods.
This document is a draft for review purposes only and does not constitute Agency policy.
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Conventional Cellulosic Biomass-Based Other Advanced
Biofuel Biofuel Diesel Biofuel
Corn starch
Organic matter
(e.g., corn starch)
for alcohols
Sugar or starch
(other than
corn)
Wastewater
biogas
Landfill gas
Corn oil extracted
from ethanol
process
Yellow
grease/rendered
fats
Virgin plant oils
(e.g., soy)
Algae
Dedicated energy
crops (e.g.,
switchgrass)
Agricultural
residues (e.g.,
corn stover)
Urban waste
Wood
residues
Figure 2-2: Examples of Feedstocks Available for Biofuel Production
With respect to biodiesel, EPA expects continued use of soybean oil, which made up 54
percent of feedstock used for biodiesel in 2009 (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 4-1 for a more detailed breakdown) (U.S. EPA, 2010b). Algae could potentially
provide large volumes of oil for the production of biomass-based diesel. However, several
hurdles, including technical issues, will likely limit production volumes within the 2022
timeframe (U.S. EPA, 2010b).
Imported sugarcane ethanol, also represents a significant potential supply of biofuel by
2022 (U.S. EPA, 2010b). In 2009, the United States imported 198 million gallons of ethanol
(EIA, n.d [d]). Import volumes are expected to grow as U.S. demand increases to meet the
biofuel targets.
2.3 Assessment of the Environmental and Resource Conservation Impacts of Biofuels
2.3.1 Approach
This report presents a comprehensive survey of environmental evaluations across the
biofuel supply chain (see below), including current and anticipated future feedstock production
and logistics and biofuel production, distribution, and use. It 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
This report therefore is the first step towards conducting a biofuels environmental life cycle
assessment (LCA), which EPA will conduct for its future Reports to Congress (see Chapter 7).
Life cycle assessment evaluates environmental impacts resulting from all stages of a
product's development—from extraction of fuel for power to production, marketing, use, and
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
87 disposal. EPA has begun to collaborate with partners and stakeholders to formulate specific
88 questions, establish boundaries, and identify critical assessment endpoints to be used in modeling
89 the input and output data for comprehensively assessing potential impacts across the biofuel
90 supply chain and integrating environmental risk assessment (ERA) tools. Although this report
91 does not attempt a comprehensive biofuel s environmental LCA, as part of the EISA-mandated
92 revisions to the RFS program, EPA conducted a life cycle assessment of GHG emissions from
93 increased renewable fuels use, which projected a 138-million metric ton reduction in CO2-
94 equivalent emissions by 2022 (U.S. EPA, 2010b). Section 4.3.2.3 provides more details about the
95 LCA methodology and results. This work, which will provide the foundation for future versions
96 of this Report to Congress, will draw from the considerable work that has already been done to
97 develop LCA and other methodologies, including ecological and human health risk assessment,
98 to assess impacts of specific biofuel products and processes.
99 2.3.2 Biofuel Supply Chain
100 There are five main stages in the biofuel supply chain: feedstock production, feedstock
101 logistics, fuel production, fuel distribution, and fuel use (Figure 2-3). The specific impacts
102 associated with a particular feedstock or biofuel will vary depending on many factors, including
103 the type, source, and method of feedstock production; the technology used to convert the
104 feedstock to fuel; methods used and distances traveled to transport biofuels; the types and
105 quantities of biofuels used; and controls in place to avoid or mitigate any impacts.
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
Biofuel Use
Vehicle Fueling &
Operation
106
107 Figure 2-3: Five Stages of the Biofuel Supply Chain
108 2.3.3 Feedstocks and Fuels Discussed in This Report
109 There is uncertainty regarding which feedstocks will be used to meet the RFS2 targets in
110 the mid- to long-term time horizon. A few feedstocks are already in use, including primarily corn
111 and soybean, as well as others in smaller quantities. Other feedstocks are in the early stages of
112 research and development or their potential future commercial viability is still unknown. This
113 report focuses on six feedstocks: the most predominantly used (corn and soybeans) and four
114 others (corn stover, perennial grasses, woody biomass, and algae) that represent a range of
115 feedstocks currently under development. The biofuels highlighted in this report are ethanol (both
116 conventional and cellulosic) and biomass-based diesel. Ethanol and biomass-based diesel are the
117 focus because they are currently the most commercially viable and/or are projected to be the
118 most commercially available by 2022, and they are the primary fuels currently projected to meet
119 RFS2. Future reports will analyze other feedstocks and fuels.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
2.3.4 Impacts Discussed in This Report
This report focuses on specific environmental and resource conservation impacts
specified in EISA Section 204, as shown in Figure 2-4 and described in Tables 2-2 and 2-3. This
report does not include extensive discussion of carbon dioxide or other greenhouse gas
emissions; interested readers are referred to the EPA's RFS2 Regulatory Impact Analysis (U.S.
EPA, 2010b). A short discussion is provided in Section 4.3.2.3 of this report. 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
analysis of these important complexities as enhanced data and analysis tools become available.
This report does not attempt to conduct a quantitative analysis of the range of impacts associated
with increased production of biofuel. Instead, it represents a compilation of available information
and analyses that can inform the nature and extent of impacts that might be expected to occur.
Thus, this report does not use a baseline year, per se, against which future impacts can be
measured. Different impacts have been assessed using applicable baselines cited in the literature
or, as appropriate, in the RFS2 RIA. Generally, however, the primary reference point used in this
document is consistent with the primary reference case used in the RFS2 RIA. This reference
case is a projection made by the U.S. Energy Information Administration prior to EISA in their
2007 Annual Energy Outlook of renewable fuel volumes expected in 2022.
RFS2-Mandated Use of
Biofuels
I
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 aquatic ecosystems
Figure 2-4: Environmental and Resource Conservation Issues Addressed in This Report
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
Chapter 3 focuses on feedstock production, including cultivation and harvest. Chapter 4
covers impacts of feedstock logistics and biofuel production, distribution, and use. Many
activities, processes, and products associated with the biofuel supply chain are already regulated,
are subject to limitations, or are mitigated through various approaches, as discussed in these
chapters. The potential impacts associated with imported biofuels are discussed in Chapter 5.
Currently, imported ethanol and biodiesel supply a relatively small percentage of U.S. biofuel
consumption—approximately 9 percent in 2008 (EIA, 2009, n.d.[a]; U.S. ITC, 2010; ERS,
2010a). If these percentages increase, future versions of this report may provide expanded
analysis of international impacts associated with imported biofuels.
EPA's ability to assess environmental and resource conservation impacts is limited by
uncertainties associated with even a qualitative assessment of the direct impacts. Many feedstock
technologies are in the early stages of research and development, therefore empirical and
monitoring data relevant to environmental impacts are limited and projections of their potential
future use are highly speculative. Recommendations in Chapter 6 and the approach to future
assessments described in Chapter 7 address how the EPA intends to bolster data availability and
analysis to improve understanding of environmental impacts in future reports.
Table 2-2: Overview of Environmental and Resource Conservation Impacts
Addressed in This Reporta
l-'eedslock Production and
1 ransporlalion
l-'uel Production. Dislrihulion. and I se
Water Quality
• Pollution of ground, surface, and
drinking water due to runoff containing
sediments, nutrients, pesticides, and
metals
• Loss of aquatic habitat due to pollution
and sedimentation.
• Water quality impacts of converting
pasture or marginal or non-cultivated
land to feedstock production
• Contamination of surface, ground, and
drinking water by wastewater from
biofuel production facilities and from
leaks and spills during fuel transportation
and storage
Water Availability
• Reduced availability of local or regional
water due to withdrawals of water
needed to irrigate feedstocks
• Loss of aquatic habitat due to lowered
stream flow
• Lowered stream flow and aquifer levels
due to water withdrawals for biofuel
conversion.
• Reduced availability of water due to
contamination (see above)
Soil Quality and Soil
Conservation
• Degradation in soil quality due to (1)
changes in land use; (2) increased use of
nutrients, pesticides, and tillage and (3)
harvesting of agricultural and forest
residue
• Soil contamination from use of
pesticides
• Soil contamination from leaks and spills
during fuel transportation and storage
• Addition of methane to soil gas resulting
from biodegradation of spilled biofuel
Air Quality
• Emissions of criteria pollutants, air
toxics, and greenhouse gases by farm
and transportation vehicles
• Fugitive dust from feedstock production
operations
• Emissions of criteria pollutants, air
toxics, and greenhouse gases during
conversion and by transportation
vehicles and off-road equipment
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
Table 2-2: Overview of Environmental and Resource Conservation Impacts
Addressed in This Reporta
l-ccdslock Production and
Transportation
l-'uol Production. Dislrihulion. and I sc
l-'.cosj slcin
Health/Biodiversity
(including invasive
and noxious plants)
• 1 lipids on Horn ;ind liiuiui ;ind loss of
ecosystem services due to pollution and
habitat changes
• Establishment and spread of invasive or
noxious plants
• 1 isUiblislimeiil ;ind spread of iii\ nsi\ e or
noxious plants
158 a - The impacts in this table are generalized and do not take into account location or effectiveness of mitigation
159 practices.
160
Table 2-3: Overview of Environmental and Resource Conservation Impacts on Specific
Ecosystems Addressed in This Reporta
l-'ccdslock Production
Forests
• Short rotation woody crop (SRWC) plantations may deplete soil nutrients over the long
run, but appropriate management techniques may increase soil nutrients.
• SRWC plantations can sustain high species diversity, although bird and mammal species
tend to be habitat generalists.
• Some tree species under consideration as feedstocks may invade forests in certain
locations.
• Forest thinning can reduce the threat of catastrophic wildfires.
• Forest thinning can increase nutrient availability in soils over the short term.
• Harvesting forest residues decreases nutrient availability, soil organic matter, and habitat
for some forest species.
Grasslands
• Conversion of grasslands to row crops impacts grassland-obligate species, potentially
leading to declines in wildlife habitat.
• Higher proportions of corn within grassland ecosystems leads to fewer grassland bird
species.
• Growing more switchgrass may improve grassland habitat for some species depending
on management regimes.
• Conversion of Conservation Reserve Program lands to perennial grasses or harvesting of
existing grasslands is likely to have low impacts on grassland species, particularly if
harvesting occurs after the breeding season.
• Use of native mixtures of perennial grasses can restore some native biodiversity.
• Cultivation of switchgrass outside of its native range may lead to invasions of native
grasslands.
• Cultivation of Miscanthus may lead to invasions of pasture and other grasslands.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
Table 2-3: Overview of Environmental and Resource Conservation Impacts on Specific
Ecosystems Addressed in This Reporta
l-eedslock Production
Wetlands
• Increased sediments, nutrients, pesticides, and pathogens from runoff can flow into
downstream wetlands.
• Increased nutrient loadings can lead to changes in wetlands community structure.
• Reduced sediment and nutrient loadings can lead to improved water quality, depending
on the specific management practice used.
• Some grass species under consideration may invade wetlands, including giant reed
(Arundo donax) and reed canary grass (Phalaris arundinacea).
• Harvesting forest residues and forest thinning may increase nutrient loads, depending on
slopes, soils, presence of buffer zones, and use of best management practices to reduce
runoff.
• Algal strains created may escape from cultivation and invade wetlands.
a - The impacts in this table are generalized and do not take into account location or effectiveness of mitigation
practices.
2.4 Regulatory Authority Relevant to Biofuel Environmental Impacts
EPA, as well as states, tribes, and local environmental agencies, has statutory
responsibility to assess and control 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.
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);
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 Clean Water Act requires permits
for point source discharges to waters of the U.S, and development of water quality standards, 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 by-products. 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.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 2: Background and Approach
Generally, EPA headquarters 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 has prepared two
documents to help biofuel facilities understand the full range of regulatory requirements (U.S.
EPA, 2007a, 2008a). While EPA has oversight authority for federal environmental regulatory
programs and regulations, state agencies and tribes are often "delegated" the responsibility for
issuing permits, conducting inspections, ensuring compliance, and taking enforcement action.
EPA regulations establish minimum requirements. States can enact more stringent standards,
although several states have enacted legislation that prohibits adopting requirements stronger
than those set by EPA.
This document is a draft for review purposes only and does not constitute Agency policy.
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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 textbox). 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
U.S. was produced from corn and refined almost entirely in the form of conventional corn starch
ethanol (FAPRI, 2010a). 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 biofuel production in the U.S. (U.S. EPA, 2010b) in the near future. As of July
2010, there was no significant commercial-scale production of ethanol from cellulosic or
hemicellulosic feedstocks, nor was there significant biodiesel production from oil seed
feedstocks other than soybean in the U.S.
As science and technology improves,
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, sweet sorghum pulp), forestry
biomass, urban waste, and dedicated energy
crops (e.g., switchgrass) (U.S. EPA, 2010b).
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 and semi-
commercial facilities. EPA expects biodiesel
from these feedstocks to gain a wider market
share as their production becomes more
economically and technologically feasible
(U.S. EPA, 2010b).
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.
This chapter reviews the actual (where known) and potential environmental impacts of
producing these six feedstocks, including impacts on water quality and quantity, soil and air
Requirements for Renewable Fuels
Under the Energy Independence and Security Act, all
renewable fuel must be made from feedstocks that
meet the EISA definition of renewable biomass,
which includes:
• 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 by-products.
• 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.
Currently, as described in the final RFS2 rule, EPA
deems renewable fuel producers using domestically
grown crops and crop residue as feedstock to be in
compliance with the renewable biomass requirements.
However, EPA will annually review U.S. Department
of Agriculture (USD A) data on lands in agricultural
production to determine if these conclusions remain
valid.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 3: Environmental Impacts of Specific Feedstocks
quality, and ecosystem health/biodiversity. Feedstock production impacts are considered during
the cultivation and harvest processes (see Figure 2-3). 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 commonalities, are discussed in Section 3.2.
Sections 3.3 to 3.5 present potential effects associated with switchgrass, woody biomass, and
algae.
Table 3-1: Primary Fuels and Feedstocks Discussed in this
Report
EISA Biofuel Type
Biofuel
Feedstock
Conventional Biofuel
Ethanol
Corn Starch
Cellulosic Biofuel
Ethanol
Corn Stover
Perennial Grasses
Woody Biomass
Biomass-Based Diesel
Biomass-Based
Diesel
Soybeans
Algae
In addition to the six primary feedstocks examined in this report, Section 3.6 briefly
discusses waste materials as potential emerging feedstocks for biofuels. In addition to general
ecosystem impacts, Section 3.7 reviews impacts on specialized habitats (forests, grasslands, and
wetlands), as required under EISA Section 204. Section 3.8 reviews environmental concerns
associated with genetic engineering of feedstocks, commonly referred to as genetically modified
organisms (GMOs).
3.2 Row Crops (Corn, Corn Stover, Soybeans)
3.2.1 Introduction
U.S. corn and soybean production
have increased steadily over the past
several decades. Increased demand for
biofuel provides additional incentive to
continue research and development for
increasing crop yields. As shown in Figure
3-1, U.S. corn production increased by
more than a factor of four between 1950
and 2010. These increases were largely
due to gains in efficiency and crop yield.
Soybean yields have also increased. For
example, soybean yields increased from
21.7 bushels per acre in 1950 to 43.9
bushels per acre in 2010 (NASS, 2010a).
U.S. Corn Production
1950 1955 1960 1965 1970 1975 1980 1985
Source: NASS, 2010a.
1990 1995 2000 2005 2010
Fisure 3-1: U.S. Corn Production
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Chapter 3: Environmental Impacts of Specific Feedstocks
71 Actual environmental impacts will vary, depending on the number of acres in production,
72 cropping techniques, implementation of conservation practices, and the location of the crop
73 acreage including hydrology, soils, and other geographic factors.
74 3.2.1.1 Current and Projected Cultivation
75 In 20099, U.S. farmers planted 86 million acres of corn, harvesting 13.1 billion bushels
76 (NASS, 2010a). Approximately 4.6 billion bushels of corn from the 2009 harvest were used to
77 produce corn ethanol. In 2010, U.S. farmers planted 88 million acres of corn, harvesting 12.5
78 billion bushels (NASS, 2010a). Approximately 4.8 billion bushels (or 38.4 percent) of corn are
79 projected to be used to produce corn starch ethanol biofuel between September 2010 and August
80 2011 (ERS, 2010c), up from 11.2 percent in the 2004-2005 harvest year (ERS, 2010b, 2010c).
81 Corn is grown throughout the U.S., but the vast majority of the crop is grown in 12 states:
82 Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska, Ohio,
83 South Dakota, and Wisconsin. Figure 3-2 shows a map of planted acres by county (for selected
84 states) in 2009.
85
86
87
88
9 As of January 2011,2009 was the last year for which USD A NASS and EIA had complete datasets.
Source: NASS, 2010b.
Figure 3-2: Planted Corn Acres by County, for Selected States (2009)
U& OepiiTTwr tfAgrcuiuie' rutoruiApKuT-iH Sulfites
Corn for All Purposes 200*9
Planted Acres by County
f or Selected States
Not Estimated
* 10.0CG
la.coa- 24 593
25.000- 49»8»
5Q.CCO- 9&.SG9
1&D.0M. 148,89$
150.000 +
Acres
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Chapter 3: Environmental Impacts of Specific Feedstocks
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 (EIA, n.d.[c]), is expected to meet this
target through a combination of increased corn yield, increased acreage, and, potentially,
improved efficiency in converting corn starch to ethanol. U.S. Department of Agriculture
(USDA) estimates that planted corn acreage will remain at 88 million acres through 2021(USDA
does not project acreage beyond 10 years), as U.S. demand for biofuel increases (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 acreage dedicated to ethanol could rise from the
current 38 percent to as high as 41 percent in 2022 (U.S. EPA, 2010b).
Concern has been raised that the demand for corn ethanol may put pressure on the
USDA's Conservation Reserve Program (CRP) (Secchi and Babcock, 2007). This program
provides farmers with financial incentives to set aside a certain portion of their cropland for
buffer zones in order to conserve wildlife habitat, reduce erosion, protect water quality, and
support other environmental goals. CRP lands are not precluded by the feedstock requirements
for renewable fuels (see text box on page 3-1) from being used to grow biofuel feedstocks.
Therefore their conversion to biofuel feedstocks could reduce the effectiveness of the CRP
program in protecting the environment, and could result in increased environmental impacts,
depending on the nature (i.e., crop) and extent of the conversion. One estimate, which examined
the state of Iowa, predicted that high corn prices could lead to the recultivation of up to 70
percent of the expiring acreage enrolled in the CRP (Secchi and Babcock, 2007). Other states
may not have such high rates of recultivation given that much of the land in the CRP is marginal
and would be expensive to cultivate.
The Food, Conservation, and Energy Act of 2008 (Farm Bill) capped CRP acreage at 32
million, reducing enrollment by 7.2 million acres from the 2002 Farm Bill and potentially
making more acreage available for corn production (ERS, 2008). In 2007, approximately 28.5
million acres or 78 percent of all CRP lands consisted of some type of grassland (FSA, 2008).
A USDA study estimates that, to meet the renewable fuel standard, total cropland will
increase 1.6 percent over 2008 baseline conditions by 2015, with corn acreage expanding 3.5
percent, accounting for most of the cropland increase (Malcolm et al., 2009). While corn acreage
is expected to expand in every region, this USDA study estimates that traditional corn-growing
areas would likely see the largest increases—up 8.6 percent in the Northern Plains, 1.7 percent in
the Corn Belt, and 2.8 percent in Great Lakes States (Malcolm et al., 2009). Historically, corn
has been grown in rotation with other crops such as wheat, hay, oats, and especially soybeans.
However, high corn prices have created incentives for continuous cultivation of corn (NASS,
2007a), and in some cases conversion of non-cropland to corn.
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 RIA, EPA 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 is no commercial production of
cellulosic ethanol from corn stover.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Because corn stover protects underlying soil from wind and water erosion, the use of corn
stover as a feedstock could increase soil erosion and environmental impacts compared to existing
practices (Sheehan et al., 2004; Williams et al., 2009). The USDA's Natural Resource
Conservation Service (NRCS) has established soil loss tolerance levels, and farmers harvesting
corn stover are encouraged to maintain a minimum level of groundcover or using other practices
to minimize soil loss. Under current rotation and tillage practices, approximately 30 to 40 percent
of stover could be collected cost effectively, taking into consideration erosion reduction, soil
moisture needs and nutrient replacement (Graham et al., 2007; Perlack et al., 2005).
Maintaining soil carbon levels is another concern that should be taken into account when
determining the extent of stover harvesting. To maintain soil carbon levels, a significant portion
of the corn stover would need to be left on fields, reducing the amount of the biomass that could
be collected for feedstock. Sustainable residue removal rates depend on tillage practices, with no-
till allowing for the greatest level of sustainable removal. Developing a single national estimate
of the amount of residue that must remain on the ground to meet conservation goals is difficult
because much depends on site-specific conditions.
After corn, soybean is the second largest agricultural crop (in terms of acreage) in the
U.S. In 2009, American farmers planted 77.4 million acres and harvested 3.4 billion bushels. In
2010, American farmers planted 77.7 million acres of soybeans and again harvested 3.4 billion
bushels (NASS, 2010a). Soybean oil is the principal oil used for commercial production of
biodiesel in the U.S., responsible for about half of total biodiesel production, with the rest
coming from various other vegetable oils such as canola oil as well as waste fats, tallow and
greases (see Table 4-1 for more detailed breakdown) (EIA, 2010). In harvest year 2008/2009,
approximately 5.6 percent of the soybean harvest, or about 1.9 billion pounds of soybean oil
(USDA, 2010b), went to biodiesel production and yielded 505 million gallons in calendar year
2009 (EIA, n.d. [d]). This was a significant decline from the production total in 2008 of 676
million gallons (EIA, n.d. [d]). Nonetheless, USDA expects the percentage of soybean harvest
going to biodiesel to increase to 7.8 percent by 2012 and holding steady through 2019. USDA
also projects that soybean oil used for biodiesel will represent 13-15 percent of total use of
soybean oil-approximately 400 million gallons of biodiesel (USDA, 2010b).10 USDA estimates
that soybean acreage will level off at approximately 76 million acres through 2019 (USDA,
2010b).
In terms of cultivation, soybeans are typically grown in the same locations as corn. Figure
3-3 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.
10 Percentages were calculated by multiplying together the percentage of soybean crop converted to soybean oil,
percentage of soybean oil converted to biodiesel, and total bushels produced, then dividing by total bushels
produced.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 3: Environmental Impacts of Specific Feedstocks
166
167 Source: NASS, 2010b.
168 Figure 3-3: Planted Soybean Acres by County (2009)
169 Much of the recent expansion in corn acreage for ethanol production has come at the
170 expense of land previously used for other crops, especially soybeans (Fargione et al., 2009;
171 Keeney and Hertel, 2009). In 2007, corn acreage expanded 23 percent in response to high prices
172 and the demand for corn ethanol production (Mitchell, 2008). This expansion resulted in a 16
173 percent decline in soybean acreage, which reduced soybean production and contributed to a 75
174 percent rise in soybean prices between April 2007 and April 2008 (Mitchell, 2008). Much of the
175 soybean acreage decrease occurred as a result of changing agricultural rotation, for example
176 some corn-soybean-corn rotations were replaced by continuous corn (Fargione et al., 2009). In
177 2008, corn acreage declined by 7.5 million acres, to 86 million acres, while soybean acreage
178 increased by almost 11 million acres. A large proportion of the soybean acreage increase came
179 from the reduction in corn acreage as well as switching crops other than corn to soybeans, loss of
180 CRP land, and an increase in soybean double cropping (Babcock and McPhail, 2009). Such
181 tradeoffs between food crops, energy crops, and CRP lands may become more critical in the
182 future, especially as climate change affects global cropland area and water availability for
183 irrigation. One study predicted that climate change will reduce global cropland area by 9 percent
184 by the year 2050, although noting that this could be buffered by the increased use of water
185 management strategies (Rost et al., 2009).
186 3.2.1.2 Overview of Environmental Impacts
187 Corn and soybean production entails the use of pesticides, fertilizer, water, and
188 fuel/energy, in addition to drainage systems, each of which can affect water quality, water
Soybeans 2009
Planted Acres by County
Mot£iJ
* I0.WQ
1U.CC0 ¦ 24
2$.000 -*0.«0
».DQ0 M.M9
IOC WO - I W OW
ysDA §
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Chapter 3: Environmental Impacts of Specific Feedstocks
189 availability, soil quality, air quality, and ecosystem health. Changes in land cover, vegetation,
190 and habitat have additional impacts on the environment. Table 3-2 summarizes these impacts and
191 the factors that influence them. (Note: Because corn stover is essentially a by-product of corn
192 production, only direct environmental impacts from stover harvest are considered for discussion
193 of this feedstock's impacts.)
Table 3-2: Impacts Associated with Biofuel Feedstock Production
(Corn Starch, Corn Stover, and Soybean)
Impiicl/Ki'suiiriT
I so (
Corn Siiirch
Iliincsl of Corn S(o\cr
So;tl>c;in
Water Quality
Corn production can lead to
erosion of sediment and the
runoff and leaching of
fertilizers such as nitrogen and,
phosphorus, and pesticides
such as atrazine. Artificial
drainage like tile drains
increases loss of nitrogen to
surface waters.
Actual water quality impacts
depend on a number of
geographic and management
factors: for instance, the rate,
timing, and method of
application of fertilizers,
manure, and pesticides; and the
use of erosion control practices
such as edge of field controls
like vegetative buffers,
controlled drainage, or
constructed wetlands.
Removal of corn stover
will require increases in
fertilizer application rates,
which can result in the
pollution of surface and
ground waters.
Erosion can also increase
as more stover is removed,
providing less ground
cover.
Actual water quality
impacts will depend on a
variety of geographic and
management factors.
The majority of soybean
acreage is managed with
conservation tillage,
minimizing erosion.
Though soybean
production requires smaller
amounts of many nutrients—
especially nitrogen—than does
corn production, it often still
requires potassium and
phosphorus, which may impact
water quality.
Actual water quality impacts
depend on a variety of
geographic and management
factors.
Water Quantity
In areas where corn production
requires irrigation, surface and
ground water quantities may
be affected.
Irrigation requirements depend
on rainfall, relative humidity,
soil properties, and crop yield.
Additional water use for
stover production is likely
to be minimal.
In areas where soybean
production necessitates
irrigation, surface and ground
water quantities may be
affected.
Irrigation requirements depend
on rainfall, relative humidity,
soil properties, and crop yield.
This document is a draft for review purposes only and does not constitute Agency policy.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Table 3-2: Impacts Associated with Biofuel Feedstock Production
(Corn Starch, Corn Stover, and Soybean)
linpiicl/Kcsoiii'co
I so (
Corn Sisirch
Iliini'sl of Corn S(o\cr
Stnliciin
Soil Quality
The conversion of uncultivated
land or marginal cropland to
corn production may lead to
higher soil erosion and lower
quantities of soil organic
matter.
Soil quality is maintained
through management practices
that include reduced use of
tillage, use of crop rotations,
and the return of organic
matter to the soil through cover
crops, manure, or crop
residues.
Excess removal of corn
stover can increase erosion,
decrease soil organic
matter and degrade water
quality. These impacts
depend on management
practices and local
conditions, including slope,
soil type, and prior land
use.
The majority of soybean
acreage is managed with
conservation tillage practices,
mitigating erosion and impacts
on soil organic matter.
Air Quality
Emissions of criteria and air
toxic pollutants are associated
with several sources, including
combustion of fossil fuels by
farm equipment; airborne
particles (dust) generated
during tillage and harvesting;
and the production and
application of fertilizers and
pesticides.
Actual impacts depend on use
rates and formulations of
fertilizers, and pesticides;
tillage methods; the type of
fuel and agricultural
equipment; and conditions at
time of tillage and harvest.
Corn stover harvesting may
affect air quality if it
requires the combustion of
additional diesel or
gasoline beyond that used
to harvest corn, if it leads
to additional fertilization of
fields, or if additional dust
is released into the air
during harvest operations.
Emissions of criteria and air
toxic pollutants are associated
with several sources, including
combustion of fossil fuels by
farm equipment; airborne
particles (dust) generated
during tillage and harvesting;
and the production and
application of fertilizers and
pesticides.
Actual impacts depend on use
rates and formulations of
fertilizers and pesticides; tillage
methods; the type of fuel and
agricultural equipment; and
conditions at time of tillage and
harvest.
Ecosystem Impacts
The type and extent of
ecosystem impacts depend on
local conditions and
management. Nutrients,
sediment, and pesticides can
contaminate surface waters and
wetlands, leading to changes in
biodiversity.
Corn stover harvest may
decrease soil biodiversity.
The water quality impacts
described above may affect
wetland biodiversity.
The ecosystem impacts of
stover removal depend on a
variety of geographic and
management factors,
including the amount of
stover removed.
The type and extent of
ecosystem impacts depend on
local conditions and
management. Nutrients,
sediment, and pesticides can
contaminate surface waters and
wetlands, leading to changes in
biodiversity.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Table 3-2: Impacts Associated with Biofuel Feedstock Production
(Corn Starch, Corn Stover, and Soybean)
linpiicl/Kcsoiii'co
I so (
Corn Sisirch
Iliini'sl of Corn S(o\cr
Stnliciin
Invasiveness
Potential
Corn is non-invasive.
See "Corn"
Soybean is non-invasive.
a - Impacts associated with corn production are described in the "Corn Starch" column.
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 systems may be used to reduce or minimize the impact
of row crop agriculture on the environment. The systems support 1) controlled application of
nutrients and pesticides through proper rate, timing, and method of application, 2) controlling
erosion in the field (i.e., reduced tillage, terraces, or grassed waterways), and 3) trapping losses
of soil at the edge of fields or in fields through practices such as cover crops, riparian buffers,
controlled drainage for tile drains, and constructed/restored wetlands (Blanco-Canqui et al.,
2004; Dinnes et al., 2002; NRCS, 2010).
The effectiveness of conservation practices, however, depends upon their adoption. The
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, 2010).
Further, even when erosion practices are reliably implemented, conservation practices
and best management practices (BMPs) are not a panacea. A case study in the Chesapeake Bay
(CENR, 2010) found that, although 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), lower nutrient input has not improved
dissolved oxygen levels overall in the Chesapeake Bay, with the exception of small-scale
reversals in hypoxia.
3.2.2 Water Quality
Water quality impacts from increased corn and soybean production for biofuel may be
significant, and 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 predict that increased production of crops for biofuels will exacerbate
water quality problems in the Gulf of Mexico and other U.S. coastal waters if the crops are not
grown under improved agricultural conservation practices and expanded nutrient BMPs (Greene
et al., 2009, and Rabalais et al., 2009, cited in CENR, 2010).
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Chapter 3: Environmental Impacts of Specific Feedstocks
3.2.2.1 Nutrient Loading
Nutrients—Surface Water Impacts
Increased production of row crops for biofuel, especially corn, will increase nitrogen and
phosphorus loading to surface waters if not managed appropriately. Excessive levels of nutrients
in a body of water can cause accelerated algal growth, reducing light penetration and oxygen
levels. Low dissolved oxygen (i.e., hypoxia) can kill fish, reducing their populations and the
species diversity in the affected area. This nutrient enrichment process (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, p. 88). Further, the National Summary of Impaired Waters
(U.S. EPA, 2010c)11 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 U.S. were impaired due to nutrient enrichment. The 2007 National Estuarine
Eutrophi cation Assessment found that the Mid-Atlantic is the region most impacted by hypoxia,
with almost 60 percent of the waters affected by anthropogenic land-based sources of nutrient
pollution, agriculture being the largest contributor (CENR, 2010). The National Summary of
Impaired Waters also reported that in 2008 over 68,000 miles of streams and rivers and over 1.3
million acres of lakes and reservoirs in the Mississippi River Basin states were impaired because
of nutrients. Increased corn and soybean production for biofuels could exacerbate this situation
due to the nutrients from additional fertilizer or increases in the acreage or extent and density of
subsurface tile drainage. The Committee on Environment and Natural Resources cites a 2008
report that predicts the average annual flux of dissolved inorganic nitrogen to the Gulf of Mexico
could increase by 10 to 34 percent, based on a "pessimistic" scenario in which corn production
acreage increases by up to 9 percent (Donner and Kucharik, 2008, cited in CENR, 2010).
In evaluating the potential for water quality impacts due to increased nutrient loads to
surface waters, there is some debate about which nitrogen compounds to consider. Not all
nitrogen compounds can be easily used by algae (i.e., are bioavailable) and thus some forms of
nitrogen impact eutrophi cation more than others. Ammonia is the inorganic nitrogen compound
that is easiest for most algae to use, followed by nitrate and nitrite (Cole, 1983). Total nitrogen is
a measure of the sum of the nitrogen present in both inorganic and organic compounds in water.
Although many studies track total nitrogen, some researchers argue that it is more
appropriate to consider inorganic nitrogen compounds only, as those are most likely to impact
water quality through eutrophi cation. When tracking the fate and transport of nitrogen in surface
waters within large watersheds (e.g., in the Mississippi River Basin), it is important to remember
that inorganic nitrogen compounds are readily converted to organic nitrogen compounds and
back to inorganic compounds by organisms present in surface waters and sediments. At the basin
scale, measuring total nitrogen provides insight into the potential maximum impact of nitrogen
inputs into surface waters.
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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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, 2010b). 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). An Iowa State University study found that each acre of harvested corn also
requires about 55 pounds of phosphorus (in the form P2O5) (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
fields 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 compared to corn and at much lower rates
(U.S. EPA, 2010b). 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, the
USDA's National Agricultural Statistics Service 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,
2007b). 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. Similar to corn,
the conversion of idled acreage to soybeans is estimated to result in losses of nitrogen and
phosphorus from the soil (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 runoff and leaching of the pollutants to water. One study estimated that 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, meaning that most of the nitrogen
runoff was due to corn production (Powers, 2005).
While the total amount of nitrogen lost from corn fields tends to be higher than losses
from soybean fields (Powers, 2005), loss of inorganic nitrogen from corn and soybean fields
tends to be similar. This suggests that eutrophic effects of nitrogen will be similar for runoff
from both corn and soybean fields in surface waters near the fields. However, when considering
impacts at the basin scale, it is more relevant to consider the total amount of nitrogen contributed
by each crop.
Use of corn stover for ethanol production would not necessarily result in increased corn
production. However, the removal of corn stover could lead to loss of soil surface cover if 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 non-point source pollutants (Blanco-Canqui and Lai, 2009a).
Typically, for each ton of corn stover harvested, an additional 16 pounds of nitrogen fertilizer
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and 6 pounds of phosphorus fertilizer must be added to the soil, though these quantities vary
considerably (Sawyer and Mallarino, 2007).
Mitigating the loss of nitrogen and other nutrients to water bodies is a research priority
for the USDA. Since drainage systems are a key conduit for nutrient loading, new research is
focusing on alternative surface and subsurface drainage solutions. 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 technology 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 its discharge into streams and rivers. Surface water runoff
control, another conservation method used to stop water erosion, reduces the loss of nutrients to
the surrounding environment through overland flow, 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). 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).
However, none of these practices guarantee environmentally sustainable biofuel
production on an industrial scale. The interactions between various BMPs need to be investigated
more closely, as there can sometimes be unexpected adverse consequences from new
technologies. For example, the 2010 report by the Committee on Environment and Natural
Resources notes that the introduction of tile-drainage systems in the Midwest has improved
agricultural yields but worsened water quality by accelerating nutrient-loaded runoff to streams
and rivers without allowing natural processes to filter the nutrients (CENR, 2010).
Nutrients—Coastal Waters Impacts
Nutrient enrichment is a major concern for coastal waters across the U.S., 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 areas documented as experiencing hypoxia increased from 12 in
1960 to over 300 in 2008 (see Figure 3-4) (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 (CENR,
2010).
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Note: Map does not display one hypoxic system in Alaska and one in Hawaii.
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Figure 3-4: Change in number of U.S. coastal areas experiencing hypoxia
from 1960 to 2008
Hypoxia in the Gulf of Mexico has been a long-standing environmental and economic
issue that threatens commercial and recreational fisheries in the Gulf (U.S. EPA, 2010b). 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 will exacerbate the problem (U.S. EPA, 2010b). U.S. Geological Survey
(USGS) SPARROW1" 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 (upstream of Cairo, Illinois) using SWAT! 4 modeling
indicated that, on average, it contributes 39 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 water through atmospheric
deposition). Atmospheric nitrogen from all sources, including power plant emissions, is
estimated to contribute 15 to 20 percent of the nitrogen loading to the Gulf of Mexico (Alexander
et al., 2008), and about 30 percent of the nitrogen loading to Chesapeake Bay (Paerl et al., 2002).
12 SPARROW (SPAlialh 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 phosphoras 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.
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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 a 1.7 percent increase in nitrogen loads to surface
water, with the greatest increases in nitrogen load occurring in the Corn Belt and Northern Plains
(Malcolm et al., 2009). EPA used the SWAT model to predict the impacts of increased corn
production to meet the RFS2 corn starch ethanol targets on water quality in Upper Mississippi
River Basin, which empties into the Gulf of Mexico. The modeling found a maximum increase
in nitrogen load to the Gulf of Mexico of 1.9 percent, and a maximum of 1 percent increase in
phosphorus load. The SWAT model also indicated that, by 2022, increased corn yields could
reduce the need for increasing the amount of land in corn, so nutrient loads could decrease from
earlier peaks (SAB, 2007).
Ecological features such as wetlands and riparian buffers play an important role in
absorbing nutrients before they run into surface waters. 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 to 78 percent of phosphorous, 76 percent of nitrogen, and 89 percent of total
suspended solids (TSS) (Schwer and Clausen, 1989).14
Nutrients—Ground Water Impacts
Excess nutrients from fertilizers can leach into ground water, which can discharge to
surface waters, thereby contributing to surface water nutrient loading. About two-thirds of the
nitrogen lost to subsurface flow eventually returns to surface water (U.S. EPA, 2010b, p. 971).
Ground water can also 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 U.S. in predominantly
agricultural areas from 1988 to 2004 and found significant increases in concentrations of nitrate
in 7 of the 24 well networks. In 3 of the 7 well networks, USGS found nitrate concentrations that
exceeded the federal drinking water standards of 10 mg/L of nitrate-nitrogen (Rupert, 2008).
Increased corn and soybean 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 (Malcolm et al., 2009). Similar estimates for soybean production
were not identified. Studies of nitrate leaching from corn and soybean rotation cropping systems
are inconclusive about whether these systems increase or decrease leaching rates (Kanwar et al.,
1997; Klocke et al.; 1999; Weed and Kanwar, 1996; Zhu and Fox, 2003).
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. The USD A
14 See also
http://cfpub.epa.gOv/npdes/stonmvater/menuofbmps/i ndex.cfm?action=factslieet_results&vievv=specific&bmp=X2.
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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 eutrophication. There may also be economic incentives for implementing fertilizer
management strategies. In 2006, the University of Minnesota Extension, an agricultural research
partnership between federal, state and county governments, estimated that 86 percent of
Minnesota farmers could save more than $6 per acre and 56 percent could save more than $10
per acre in fertilizer costs by following better informed nutrient application rates (Minnesota
Department of Agriculture, 2010).
3.2.2.2 Sediment
Nutrients and sediment are the two major water quality problems in the U.S., and much
attention has been focused on these issues in the Mississippi River Basin and the Gulf of Mexico
(NRC, 2008, p. 88). Use of soil erosion control practices is widespread, yet 15 percent of acres in
the Upper Mississippi River Basin experience excessive sediment loss (NRCS, 2010). The
National Water 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, 2010c).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 viable
seeds sufficiently to prevent germination (Gleason et al., 2003). EPA and USDA have evaluated
the impact of the RFS2 rule on sediment loads. As reported in the water quality analysis
conducted by EPA for the RFS2 rule, it is estimated that annual sediment loads to the Mississippi
River from the Upper Mississippi River Basin would increase by 6.22 million tons (15 percent)
between 2005 and 2022, assuming corn stover remained on the field following harvest
(AquaTerra, 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 is expected to increase
sediment yield to surface waters and wetlands, but rates are highly variable depending on soils,
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
(AquaTerra, 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, 2010b).
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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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 the USD A, 41 percent of planted acreage in the U.S. uses
conservation tillage as a mitigation strategy (ARS, 2006). These techniques have been shown to
reduce erosion by as much as 60 to 90 percent, depending on the conservation tillage method
(Minnesota Department of Agriculture, 2010). In 2002, the USDA Agricultural Research Service
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).
3.2.2.3 Pesticides
According to the National Summary of Impaired Waters (i.e., waters that do not meet the
water quality standards) (U.S. EPA, 2009a, 2010d), over 16,000 miles of streams and rivers and
over 370,000 acres of lakes and reservoirs in the U.S. were impaired in 2008 because of
pesticides, with atrazine (commonly used in corn production) specifically cited by several states
(U.S. EPA, 2010c). Atrazine was also estimated to be the most common pesticide lost from
agricultural lands in the Upper Mississippi River Basin (NRCS, 2010).
Corn production uses more pesticides than predicted for any other potential biofuel crop
produced in the U.S. (Pimentel and Patzel, 2005; Pimentel and Pimentel, 2008, p. 380; Ranney
and Mann, 1994). USDA's NASS estimates that insecticides were applied to 16 percent of the
2006 soybean-planted acreage (NASS, 2007b). 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 (Hill et al., 2006).
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 FIFRA registration process is intended to minimize these risks. Many factors
contribute to the relative risks of pesticides on the environment, including fate and transport
characteristics, method of application, depth to ground water, and proximity to receiving waters.
To protect consumers against risks posed by ingestion of these pesticides, FFDCA requires the
establishment of pesticide residue tolerances on food using a standard of reasonable certainty of
no harm.
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 prior to planting to
partially incorporate the residue into the soil.
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Growing continuous corn (rather than 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). A USDA study projects that
cropland dedicated to continuous corn will increase by more than 4 percent by 2015 to reach the
15 billion gallons per year of ethanol from corn target (Malcolm et al., 2009). In addition,
increases in corn acreage and any conversion to corn of crops other than corn will most likely
increase total herbicide use. Increased corn and soybean production can result in the increased
use of herbicides that can run off or leach into surface water or ground water sources.
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 very
precise timing of pesticide applications to minimize pesticide use. In addition to providing
environmental benefits of lower pesticide use, IPM often results in lower chemical pesticide
expenses and pest damage to crops, as well as preventing the development of pesticide-resistant
pests (Minnesota Department of Agriculture, 2010). 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).
3.2.2.4 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—
may be released into surface or ground water when manure is applied to fields (Brooks et al.,
2009; Lee et al., 2007a; 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 (i.e., distance
to surface or ground water) 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 prior to application
can reduce runoff. 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).
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3.2.3 Water Quantity
3.2.3.1 Water Use
Over the entire biofuel supply chain (see Figure 2-3 in Chapter 2), crop irrigation is by
far the most significant use of water in the ethanol production process, and it tends to be much
higher than water use for most other non-renewable forms of energy on an energy content basis
(Wu et al., 2009). In some geographic locations this could lead to serious impacts on already
stressed water supplies, while in other locations water supply availability impacts are less likely
to occur. Future assessment of biofuel feedstocks will need to consider restrictions on water use
due to competing demand for water resources (Berndes, 2002).
For both corn and soybeans, the source for water used to irrigate crops varies from region
to region. In the West, surface water is largely used to irrigate crops; in the Great Plains and
Midwest, where the majority of corn and soybean production takes place, farmers rely heavily on
ground water (Kenny et al., 2009). In the future, as corn production increases to meet ethanol
demands, both geographical factors and the type of land/crop conversion will determine water
use impacts. Water use will increase as land in pasture or other low- or non-irrigated uses are
converted to irrigated corn production, especially in places like the Great Plains, where water
demand for corn irrigation is high. Converting other crops, soybeans in particular, into corn will
have little effect on water use in the Midwest, but could increase the total amount of water used
for irrigation in the Plains because of corn's relatively high water use intensity on a per area
basis (NRC, 2008).
Corn
Corn is relatively water-intensive compared to other crops. In some parts of the country,
water demands for corn are met by natural rainfall, while in other places supplemental irrigation
is required. For instance, in Iowa in 2007, less than 1 percent of the more than 14 million acres
planted in corn was irrigated. In contrast, over 60 percent of Nebraska's 9.5 million acres of corn
was irrigated in the same year (NASS, 2009).
Irrigation use for U.S. corn has been estimated to vary from a low of approximately 8
gallons of water per gallon of ethanol on average in Midwest states in one study (Wu et al.,
2009) to a high of up to 1,000 gallons for states in the Great Plains in another study (Dominguez-
Faus et al., 2009). While the data and methodology used to calculate these estimates are not
uniform across studies, in general, water use is likely to be less than 500 gallons (perhaps
substantially less) of irrigation water per gallon of ethanol in the Midwest and greater than 500
gallons per gallon of ethanol in more arid parts of the country (supporting information for Chiu
et al., 2009). Taking into account the total volume of corn starch ethanol produced, this might
translate into approximately 5 billion gallons of irrigation water in a single season in places like
Iowa and Illinois versus 300 billion gallons in Nebraska (Chiu et al., 2009). The 2007 U.S.
national ethanol-production-weighted average farm-to-fuel pump water requirement per gallon
of ethanol in the U.S. was estimated to be 142 gallons (Chiu et al., 2009).
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Corn Stover
Allocation of proportionate water use based on the energy captured from corn starch
versus stover may be studied in the future as corn stover becomes a more common biofuel
feedstock. Water use for corn stover above and beyond corn cultivation is likely to be minimal or
negligible if undertaken with resource conservation practices, especially in the most productive
corn-growing regions of the U.S. where corn stover is not functionally necessary for retention of
soil moisture. If, however, corn stover is removed from dry corn cultivation areas with
supplemental irrigation (states like Nebraska), loss of soil moisture that would have otherwise
been retained by corn stover cover and contributed to productivity of the next season's crop
(Blanco-Canqui and L al., 2009b) could necessitate additional irrigation.
Soybeans
Water for soybean cultivation, like corn, also comes from both natural precipitation and
through irrigation. In some places, the water requirements are largely met with precipitation. For
example, in 2007 in the leading soybean-producing state of Iowa, 8.6 million acres of soybeans
were grown of which less than 1 percent was irrigated (NASS, 2009). In 2007 Nebraska grew 3.8
million acres of soybeans, of which over 40 percent was irrigated (NASS, 2009).
Average nationwide rates of soybean irrigation are estimated at 3,000 to 6,000 gallons of
irrigation water to produce a volume of biodiesel equivalent to a gallon of gasoline (U.S. DOE,
2006; Dominguez-Faus et al., 2009). These rates are not applicable to states such as Iowa, where
most soybeans are grown without irrigation. In Nebraska, however, where irrigation is heavily
utilized, greater than 4,000 gallons of irrigation water per gallon of gas equivalent is not an
unusual investment of water resources for biofuel production (supplemental information to
Dominguez-Faus et al., 2009). Overall, irrigation estimates for soybeans tend to be greater than
those needed to produce a volume of corn starch ethanol equivalent to a gallon of gasoline
(Dominguez-Faus et al., 2009).
3.2.3.2 Water Availability
Because agriculture accounts for such a large share of water use in the U.S. (35 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. In particular, land conversion to corn for increased production of ethanol could
create more demand for water, adding to existing water constraints and potentially creating new
ones. The Great Plains states already have shortages, and water availability may decrease further
when typically non-irrigated pasture and CRP land is converted to irrigated corn production.
Converting other crops, soybeans in particular, into corn will have little effect on water use and
availability in the Midwest, but could increase the total amount of water used for irrigation in the
Plains because corn requires more water than soybeans on a per area basis in that region (NRC,
2008).
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
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water availability required for other purposes such as power generation, public water use, 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. Because over 85
percent of irrigation withdrawals come from underground aquifers, ground water availability is
likely to be affected the most.
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 is largely affected
by ground water withdrawals for irrigation. The consequences of excessive ground water
withdrawal can include reduced water quality, prohibitive increases in the costs of pumping,
reduced surface water levels through hydrological connections, and subsidence (Reilly et al.,
2008). Several regions (e.g., High Plains aquifer, Lower Mississippi River alluvial aquifer) that
are already experiencing water shortages could be substantially impacted by increased corn
production for ethanol. Ground water withdrawals also have indirect impacts on stream flow.
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).
3.2.4 Soil Quality
3.2.4.1 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 relative to the remaining soil (Brady and Weil, 2000). 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, 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, 2010). Moreover, CRP acreage in riparian areas
slows runoff, promoting the deposition of sediment, nutrients, and other chemicals. The USDA's
Farm Service Agency 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 U.S. Southern
Piedmont region, for example, can exhibit soil stability equal to forested or conservation-tilled
land; converting this type of land to conventional corn production will increase soil erosion
(Franzluebbers et al., 2000). In contrast, if much of the increase in corn or soybean production
comes from a shift from other crops (in 2007, for example, the increase in corn acreage came
predominantly from a decrease in soybeans), the effect on soil erosion is likely to be much
smaller. Allocation of a higher percentage of corn or soybeans for biofuel production to land
currently in agricultural use likely will not alter soil erosion rates.
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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 the CEAP report, conservation tillage
is practiced on 96 percent of all crop acreage in the Upper Mississippi River Basin, with 23
percent in no-till, and only 5 percent in continuous conventional tillage (NRCS, 2010).
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 are classified as highly erodible land, where tillage practices are generally restricted by
the conservation compliance provisions of the 1985 Food Security Act (Secchi et al., 2009).
These compliance provisions can require corn-soybean rotations with no-till cultivation (Secchi
et al., 2009).
Finally, removal of corn stover beyond a certain threshold may increase soil erosion
rates. Due to this and cost concerns, a recent study suggested that only approximately 30 percent
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of corn stover would be available for sustainable harvesting in the U.S. if erosion rates were to
be kept lower than soil loss tolerances (T-values) as defined by the USD A NRCS (Graham et al.,
2007). Because of wind erosion, the potential for corn stover removal in the Western Plain 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 are estimated to increase from approximately 30 to 50
percent (Graham et al., 2007). Yet, even with no-till management, corn stover removal rates at or
higher than 50 percent have been shown to increase erosion potential (Blanco-Canqui and Lai,
2009a).
3.2.4.2 Soil Organic Matter
Soil organic matter is critical 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 cultivated acreage.
Corn production will negatively impact soil quality on acreage where organic matter has
accumulated over time—for example, grasslands. If conventional tilling is used, a loss of organic
matter both to erosion and to the atmosphere as carbon dioxide due to increased microbial
decomposition is likely to occur (Reicosky et al., 1995). Estimates of carbon loss following
conventional tilling of previously undisturbed soils range from 20 to 40 percent—although how
much carbon is respired to the atmosphere versus lost to erosion is unclear (Davidson and
Ackerman, 1993). Assuming carbon loss to the atmosphere, it has been estimated that conversion
of grasslands in CRP to corn production would create a carbon debt requiring approximately 48
years to repay (Searchinger et al., 2008). In contrast, 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 (Adviento-
17 Defined as any tillage practice that leaves less than 15 percent of crop residues on the soil surface after planting.
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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Borbe et al., 2007; Drinkwater et al., 1998; Lai, 2003). While soil quality degrades overtime,
yields and production can be maintained by the use of fertilizers both commercial and organic.
The harvesting of crop residues, such as corn stover, removes plant material that would
otherwise remain on and potentially be incorporated into the soil. The removal of corn stover
therefore has important implications for soil quality, chiefly via effects on soil retention, organic
matter content, nutrients, and compaction. 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). Therefore, there is concern that high stover removal rates may
decrease soil carbon sequestration and lower crop yields (Karlen et al., 2009). Whatever the
removal rate for a particular site, it has been recommended that soil erosion and organic matter
content 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). Research to date suggests corn stover
removal rates should be determined based on site-specific criteria to maximize soil quality.
3.2.5 Air Quality
Air quality impacts during cultivation and harvesting of corn and soybeans are associated
with emissions from combustion of fossil fuels by farm equipment and from airborne particles
(dust) generated during tillage and harvesting. Soil and related dust particles (e.g., fertilizer,
pesticide, manure) become airborne as a result of field tillage, especially in drier areas of the
country. In addition, emissions result from the production 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. Subsequent stages in the biofuel supply chain (see Figure 2-3),
including feedstock logistics and biofuel production, distribution, and use, also affect air quality
and are discussed in Chapter 4.
3.2.5.1 Cultivation and Harvesting
Cultivating and harvesting corn and soybeans require a range of mechanized equipment
that utilize different fuels, including diesel, gasoline, natural gas, and electric power (Sheehan et
al., 1998a). 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 (SO2) (primarily from gasoline), and
coarse and fine particulate matter (PM10 and PM2.5). Gasoline use may also result in benzene,
formaldehyde, and acetaldehyde emissions. For corn, approximately 14 gallons of diesel fuel is
used per acre for tillage, harvest, and hauling. Fuel use for tillage comprises more than half of
this amount; actual usage depends on soil properties and conditions (Iowa State University,
2009). 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).
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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).
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 SO2,
NOx, carbon dioxide (C02), and mercury emissions.
Corn with a moisture content of over 18-20 percent may require drying prior to storage
to avoid spoilage (South Dakota State University, 2009). Grain driers use liquid 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.
3.2.5.2 Fertilizers and Pesticides
Pesticides are commonly used on both corn and soybeans, with corn having more
intensive application rates (NRC, 2008, p. 3, as cited in U.S. EPA, 2010b) 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,
2007b). Soybeans have the capacity to derive nitrogen from the atmosphere and therefore require
less external nitrogen fertilization than corn, resulting in less nitrogen runoff in the surface water.
Air emissions associated with fertilizer manufacturing and transport include NOx, VOC,
CO, and particulate matter (PMi0 and PM2.5), while pesticide production and blending may result
in emissions of 1,3-butadiene, benzene, and formaldehyde.
Application of fertilizers and pesticides may result in releases to the air and volatilization
of pesticide ingredients. The primary pollutants associated with the releases to air are benzene
and acrolein. The results described are consistent with another study, which found increases in
benzene, formaldehyde, acetaldehyde, and butadiene emissions, although that study included
feedstock transport and so is not directly comparable (Winebrake et al., 2001). 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).
3.2.6 Ecosystem Impacts
3.2.6.1 Eutrophication, Erosion, and Biodiversity Loss
The impact of increased corn and soybean cultivation on ecosystem and biodiversity
depends, in large part, on where crop production occurs and what management techniques are
used. Major ecosystem-related impacts that could result from additional corn and soybean
production are eutrophication, soil erosion and its associated increase in turbidity of receiving
waters and sedimentation in basins, and impacts to biodiversity. Eutrophication can occur as
fertilizer application increases nutrient loadings (nitrogen and phosphorus) in surface waters such
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as streams, rivers, lakes, wetlands, and estuaries (U.S. EPA, 2010b). Increased phosphorus
concentration has been correlated with declines in invertebrate community structure, and high
concentrations of ammonia nitrogen are known to be toxic to aquatic animals. Severe oxygen
depletion and pH increases, both of which are correlated with eutrophication, have been known
to cause growth problems and mortality in fish and invertebrates (U.S. EPA, 2010b). In addition,
as aquatic systems become more enriched by nutrients, algal growth can cause a shift in species
composition. Hypoxia threatens commercial and recreational fisheries in the Gulf of Mexico
(U.S. EPA, 2010b) and limits biodiversity (Wang et al., 2007a).
Soil erosion can also lead to an increase in wetland sedimentation, which may, depending
on sediment depths, cover viable seeds sufficiently to prevent germination (Gleason et al., 2003).
In aquatic ecosystems, sediments increase turbidity and water temperatures and bury stream
substrates, limiting habitat for coldwater fish (U.S. EPA, 2006a).
In areas where corn production is already significant, increased corn acreage can further
reduce landscape diversity (Landis et al., 2008), which might in turn impact other aspects of
biological diversity and the ecosystem services associated with biodiversity. In Iowa, Michigan,
Minnesota, and Wisconsin, biological control of soybean aphids was found to decline as the
proportion of corn in the local landscape increased, resulting in increased expenditures for
pesticides and reduced yields (Landis et al., 2008). In the Prairie Pothole region of Iowa,
Minnesota, North Dakota, and South Dakota, landscapes with higher proportions of corn acreage
had comparatively fewer grassland bird indicator species (Brooke et al., 2009). If landscape
diversity decreases (especially in the case of transforming CRP land into corn production),
migratory birds will lose habitat and likely decline in numbers. On CRP lands, several grassland
bird species have increased in abundance, and it is estimated that, without the 3 million hectares
of CRP in the Prairie Pothole region of the U.S., 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
has potential consequences on aquatic ecosystems and local biodiversity. Removing crop
residues from farm fields has been shown to affect both terrestrial and soil biota. Crop residue
removal has been correlated with decreases in the diversity of biota (Lai, 2009; Johnson et al.,
2006).
Intensification of soybean production and pesticide use may also threaten biodiversity
and nearby biota (Artuzi and Contiero, 2006; Koh and Ghazoul, 2008; Pimentel, 2006). The
change in local habitat from corn-soybean-corn rotation to continuous corn production may
decrease the support for biological control in soybean cropping systems, as reduced landscape
diversity decreases the habitat availability of many insects and animals in the local region
(Landis et al., 2008). Also, agricultural herbicides affect the composition of local plant
communities, which then affects the abundance of natural enemy arthropods and the food supply
of local game birds (Taylor et al., 2006). Fungicide pollution from runoff events has been shown
to impact algae and aquatic invertebrates in areas where soybeans are intensively grown (Ochoa-
Acuna et al, 2009).
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3.2.6.2 Invasive Plants
Modern varieties of corn and soybeans under production today in the U.S. 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 U.S. However, since U.S. seed and biotechnology companies
working to improve feedstocks may propagate corn in areas such as Mexico where corn and its
progenitors originated, it is possible that novel corn cultivars or their hybrids could spread
beyond the cultivated fields and survive. This potential for intermixing genetically modified
plants with ancestral land acres is the subject of international scientific and regulatory interest
(Mercer and Wainwright, 2008).
The extensive cultivation of row crops that are genetically engineered to resist the
herbicide glyphosate 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 ten agricultural weeds in the U.S.; loss of effectiveness of glyphosate could
encourage the use of more toxic herbicides (NRC, 2010).
3.2.7 Assessment
Corn and Soybean Acreage: Between September 2010 and August 2011, approximately
38.4 percent of corn consumed domestically is projected to be converted into ethanol biofuel
(NASS, 2010a; ERS, 2010c). 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 85.9 million acres
to 90 million acres in 2019 to meet the 15 billion gallons per year annual target under EISA
(USD A, 2010c). Currently, 5.6 percent of the soybean harvest goes to biodiesel production, and
USDA expects this percentage to increase to 7.8 percent by 2012 and hold steady through 2019.
USDA also expects that soybean acreages will hold steady at 76 million acres, though this
number may be higher to meet the EISA target. Moreover, it may be necessary to increase
acreage yield, or the portion of the soybean harvest that is devoted to biodiesel in order to meet
EISA targets (FAPRI, 2010a). Use of corn stover for ethanol production is not expected to
increase acreage dedicated to corn.
Land Use/Land Cover Change: 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 previously uncultivated acreage will likely have varying degrees of
environmental impacts, depending on site-specific characteristics.
Water Quality: Increasing production of corn for ethanol and soybeans for biodiesel may
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. Private drinking water wells could see increases in nitrate and
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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 offset by
increasing per-acre corn and soybean yields and by implementing comprehensive conservation
systems. 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 nitrogen and phosphorus to surface waters; harvesting corn stover
may reduce soil nutrient availability, leading to increased fertilizer applications
Water Availability: The magnitude of environmental impact from increased corn and/or
soybean production for biofuel will vary geographically. If corn replaces other crops in the
Midwest, water availability will be minimally impacted. Increased corn and soybean production
in areas requiring irrigation, such as 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 U.S.
Soil: Impacts of expanding corn and soybean production will vary, depending on the
converted land use. Negative soil quality impacts will arise from converting acreage protected
with perennial vegetation to conventional corn and soybean production, which will likely
increase soil erosion, sedimentation, and nutrient losses. Removal of corn stover for ethanol may
lead to a decline in organic matter, decreasing soil carbon sequestration and adversely impacting
crop yields. Impacts can be minimized through site-specific BMPs that limit soil erosion and
ensure that the amount of residue remaining on the field sustains soil quality and nutrient inputs
for subsequent crop productivity.
Air Quality: 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 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: Ecosystem health/biodiversity impacts include
degradation of aquatic life due to eutrophication, 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.
Invasive Species: Corn and soybean typically are not invasive in the U.S. corn and
soybean-growing regions.
3.2.7.1 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 soybean and corn production are determined by where
the production occurs and the types of management practices employed, including
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the extent of tile drainage. However, it is highly uncertain where production will
occur and the extent to which BMPs will be employed. In particular:
— Increased corn and soybean yields may offset the need for increased acres
in production to achieve EISA goals in 2022. However, the extent to
which yield increases will occur 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 BMPs are currently implemented on cropland
nationally is unknown, and the potential for future improvements,
including improvements in yield; management of nutrients, 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
National Agricultural Statistics Services.
• 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. Estimates of water use to
produce soybeans for biodiesel are even less certain than those for corn
production. The connection between water use for corn and soybean production
and impacts on water availability and water shortages is also surrounded by
uncertainty. 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, 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. For example, if
the USDA soybean acreage projections hold and additional soybean acreage is not
required to meet biodiesel demand, then the impact of soybeans for biodiesel on
soil quality is likely to be relatively minimal. However, if soybean acreage
increases beyond current levels, determining how much land is being converted,
the previous crop-type of that land, and its geographical location will be necessary
to assess the impact of this increase on soil quality. More studies on land use/land
cover changes as a result of ethanol and biodiesel demand are needed.
• Secondarily, uncertainties regarding the effect on soil quality are caused by lack
of detailed land management data. For example, more frequent and detailed
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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 water quality with respect to fertilizer and
pesticide use and application. In addition, NOx emission rates from fertilized soil
are highly uncertain and variable as they rely on microbial conversion of fertilizer
to nitrate which in turn is influenced by environmental conditions. The extent to
which cover crops and tillage practices are employed, both of which can reduce
fugitive dust emissions, are also highly uncertain. 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 highly
impacted by uncertain environmental factors such as nutrient and sediment runoff.
Nutrient loadings from row crop production into surface waters depend on a
variety of factors, including variations due to weather and are therefore widely
variable (Powers, 2007). Regardless, the ability to reduce chemical exposure of
biota will 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.
• There is substantial uncertainty regarding the impacts of climate change on
regional precipitation patterns and temperatures, which could significantly change
water demand and availability, crop yield, runoff, and soil loss.
3.3 Perennial Grasses
3.3.1 Introduction
Perennial grasses are herbaceous plants that grow in successive years from the same root
system. They lack the sugar and starch content to be converted directly into ethanol using
conventional methods, but can be converted using cellulosic conversion technologies. While
cultivation of perennial grasses has potential environmental advantages over traditional row
crops such as corn and soybeans, major technological challenges exist for the development of
these more advanced biofuel conversion technologies. Currently, no commercial-scale facilities
for converting perennial grasses to cellulosic ethanol are operating in the U.S.; however, six
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), hereafter
referred to as Miscanthus. Research suggests that an aggressive genetics program to create fast-
growing strains could increase production of both feedstocks dramatically over current
production levels (Vogel and Masters, 1998). The research community is also exploring mixtures
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Chapter 3: Environmental Impacts of Specific Feedstocks
of native grassland species—referred to as low-input high-diversity (LIHD) mixtures—as a
feedstock (see text box on next page). Compared to their constituent monoculture perennial
grasses, LIHD mixtures have often demonstrated higher bioenergy yields (i.e., gallons of biofuel
produced per unit of land), and a greater ability to grow in infertile soils, although much less is
known about their commercial potential (Tilman and Lehman, 2006). Most research and
development has been conducted on monocultures of switchgrass and Miscanthus, therefore,
these species are the focus of this section.
Switchgrass, a native plant of North America, has historically been grown in the U.S. as
forage for grazing livestock (Parrish and Fike, 2005). Recently, it has entered breeding programs
and agronomic testing as a biofuel feedstock. Miscanthus, which is native to Asia, has been
developed and tested as a biofuel feedstock largely in Europe. Considerable genetic variation in
both these species has yet to be explored to optimize feedstock production and biofuel refining
(Keshwani and Cheng, 2009), but promising traits, including low lignin and ash content, and late
or absent flowering periods (Jakob et al., 2009), indicate ample potential for high crop yields and
efficient conversion to ethanol (Jakob et al., 2009). While standard irrigation, fertilizer, and
pesticide use practices have yet to be developed, recent small-scale farming and larger-scale
studies, such as those conducted by the U.S. Department of Energy's Regional Biomass Energy
Feedstock Partnership, continue to inform estimates of biofuel perennial grass cultivation and
resource requirements (Parrish and Fike, 2005). Farm-scale studies have demonstrated that
ethanol yield from switchgrass ranges from approximately 240-370 gallons per acre compared to
an average of 330 gallons per acre for corn grain (Schmer et al., 2008).
EISA and Section 21 l(o) of the Clean Air Act limit land conversion for biofuels to
existing agricultural land cleared or cultivated prior to Dec. 19, 2007, or land that was non-
forested and actively managed or fallow on Dec. 19, 2007 (Clean Air Act, Section 21 l[o]). As of
November 2009, approximately 28 million of the 31.2 million CRP acres were vegetated with
mixtures of native or introduced grasses for a variety of environmental purposes, including
wildlife habitat, erosion control, and water quality. Economic modeling of global bioenergy
markets (POLYSYS) estimates that approximately 8-13 million acres of CRP land and 10-23
million acres of agricultural cropland in the U.S. could possibly (but not necessarily likely) be
converted to switchgrass production, depending on economic factors (Walsh et al., 2003). The
gross impact on CRP land already growing switchgrass would be minimal, and the estimated
combined conversion of "idle" and "pasture" lands to switchgrass production could be between
0.78 and 5.58 million acres (Walsh et al., 2003). Comparable quantitative information is not
available for Miscanthus, however, high biomass yields on areas with poor soil quality in
southern Illinois demonstrate the potential for Miscanthus on low fertility lands (Pyter et al.,
2004). In addition to CRP land, abandoned cropland is hypothetically available for perennial
grass cultivation. Assuming suitable technology and infrastructure exists, an estimated 25 billion
gallons of ethanol could potentially be produced annually if switchgrass is grown on the
approximately 146 million acres of abandoned agricultural land in the U.S., as long as these
lands do not fall under restrictions described in Section 21 l(o) of the Clean Air Act (U.S. EPA,
2010b, Chapter 6).
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Native Grasslands as a Biofuel Feedstock
Recent research has suggested using mixtures of native perennials as a feedstock on marginal or infertile
lands (Tilman et al., 2006; Tilman et. al, 2009; Campbell et al., 2008; Weigelt et al., 2009). This practice
is limited by several technological and management hurdles, yet also enjoys 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 comprised 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), and reduced potential for plant disease and crop losses
(Fargione et al., 2009; Hooper et al., 2005; Loreau et al., 2002; Reiss 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; Zavaleta, 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 that of the mixture (Cardinale et al., 2006;
Loreau et al., 2002; Cardinale, 2007). Although it seems likely that highly productive feedstocks (e.g.,
switchgrass and Miscanthus) managed for maximum production will produce more biomass for biofuel
production than LIHD mixtures, there are no direct field-scale comparisons between LIHD and other
feedstocks with which to evaluate this assumption. The only comparison to date found that switchgrass
grown on productive lands across the Midwestern corn belt (Nebraska, South Dakota, North Dakota) out-
produced LIHD grown on unproductive land in Minnesota (Schmer et al., 2008). However, 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). 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.
3.3.1.1 Current and Projected Cultivation
Perennial grasses could thrive across many regions of the contiguous U.S. (see
Figure 3-5). Since many of these species, including switchgrass, have historically dominated
much of the Midwestern landscape, they are well suited to grow over much of the agricultural
region.
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1056
1057 Source: Dale et al., 2010, updated from Wright 1994
1058 Figure 3-5: Generalized Map of Potential Rain-fed Feedstock Crops in the Conterminous
1059 United States Based on Field Plots and Soil, Prevailing Temperature, and Rainfall Patterns
1060 3.3.1.2 Overview of Environmental Impacts
1061 As production of biofuel from perennial grass becomes technologically and economically
1062 viable, demand for perennial grass will increase. This will result in conversion of qualifying land
1063 to perennial grasses, the location and extent of which will depend on region-specific agricultural
1064 and economic conditions. Perennial grass production will likely require traditional agricultural
1065 activities, including pesticide, fertilizer, water, and fuel/energy usage. The intensity of these
1066 activities relative to the land management practices they are replacing will determine the extent
1067 to which perennial grass production impacts water quality, water availability, air quality, and soil
1068 quality. Finally, perennial grass feedstock transport, which often involves seed movement, may
1069 result in unintended dispersal and the spread of invasive grasses.
1070 3.3.2 Water Quality
1071 Perennial grasses, sometimes grown as a conservation practice along the margins of
1072 agricultural fields to reduce sediment and nutrient runoff into surface water and wetlands, are
1073 expected to have fewer water quality impacts than conventional agricultural crops (Keshwani
1074 and Cheng, 2009). This will depend, however, on the agricultural intensity of the perennial grass
1075 cropping system (e.g., the extent of fertilizer and pesticide use). Table 3-3 shows inputs needed
1076 to grow perennial grasses compared to agricultural intensity metrics associated with growing
1077 conventional crops.
Willows
Hybrid Poplars
Miscanthus
Hybrid Poplars
Switchgrass
Sorghum
Switchgrass
Hybrid Poplars
Switchgrass
Hybrid Poplars
Miscanthus
Pine
Sorghum
Sweetgum
Switchgrass
Sorghum
Switchgrass
Energy Cane
Eucalyptus
Pine
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Table 3-3: Comparison of Agricultural Intensity Metrics for
Perennial Grass and Conventional Crops
Mdric
Reduction Kcl;ili\c to ( orn-W lic;il-Su\l>ciin A\cr;iiic
Erosion
125 fold
Fertilizer
1.1 fold
Herbicide
6.8 fold
Insecticide
9.4 fold
Fungicide
3.9 fold
Source: Ranney and Mann, 1994.
3.3.2.1 Nutrient Loading
Nutrients—Surface Water Impacts
Relative to annual crops, such as corn and soybeans, production of switchgrass and
Miscanthus requires less fertilizer and reduces nutrient runoff. Switchgrass is inherently efficient
in its nitrogen use, as well as its use of potassium and phosphorus (Parrish and Fike, 2005).
Switchgrass and Miscanthus are both nutrient-efficient because they store carbohydrates and
nutrients in their roots at the end of the growing season (Beale and Long, 1997; Beaty et al.,
1978; Simpson et al., 2008). Therefore, the practice of harvesting the above-ground biomass
reduces the need for fertilization in subsequent growing seasons. A recent study reported that
Miscanthus can fix atmospheric nitrogen, which could be a large benefit to its use as a feedstock
(Davis et al., 2010). Studies have shown no response in Miscanthus growth to nitrogen additions,
suggesting these fertilizers are not needed in its production (Clifton-Brown et al., 2007;
Danalatos et al., 2007). In contrast, switchgrass yields increase with nitrogen fertilization, with
recommended application rates for switchgrass grown for biofuels ranging from 41 to 120 kg
nitrogen/ha/year (37 to 107 lbs nitrogen/acre/year), varying by region (McLaughlin and Kszos,
2005). Data for switchgrass and Miscanthus have been generally based on experimental plots,
and management and yields may differ at the farm-scale. However, if these lower nitrogen
fertilization rates hold, average nitrogen losses to surface waters should be lower relative to the
production of corn starch ethanol (ORNL, n.d.).
Nutrients— Coastal Waters Impacts
As mentioned above, switchgrass and Miscanthus cropping systems are expected to
require fewer fertilizer additions compared to 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 minimize their impact on the hypoxic zones of U.S. coastal waters.
3.3.2.2 Sediment
Switchgrass and other perennial grasses have been 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 have been shown to reduce erosion 125-fold
when compared to an average of corn, wheat, and soybeans (see Table 3-3). Therefore, assuming
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good agricultural practices, switchgrass production is not expected to increase sediment loads to
surface waters.
3.3.2.3 Pesticides
Perennial grasses, such as switchgrass (native to the U.S.), are generally less susceptible
to pests than traditional row crops (Oyediran et al., 2004; Keshwani and Cheng, 2009). A 2004
controlled greenhouse study found that recovery of a dominant pest (western corn rootworm)
was 0.2 to 82 times more likely from corn than from 20 other grass species native to the Midwest
(Oyediran et al., 2004). However, most species are likely to be more susceptible to pests when
grown in monocultures as compared to polycultures. 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. In non-commercial
production, pesticide releases from perennial grass plantings are much less than from corn or
soybeans (Hill et al., 2006). 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 plantings for harvest. Switchgrass filter strips have been shown to
reduce dissolved atrazine and metachlor concentrations in runoff (Keshwani and Cheng, 2009).
Information relevant to potential pesticide use for Miscanthus in the U.S. is generally lacking;
however, researchers in Europe have reported that pesticide requirements are low compared to
row crops (Lewandowski et al., 2000).
Of particular concern is how 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 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).
3.3.2.4 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.
3.3.3 Water Quantity
3.3.3.1 Water Use
Switchgrass is an important native grass in prairies across North America and does not
require additional irrigation. As such, 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 (Dominguez-Faus et al., 2009; Wu et al., 2009). Nonetheless,
greenhouse and field studies indicate switchgrass significantly increases biomass production with
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access to ample water (Barney et al., 2009; Heaton et al., 2004). Thus, farmers may irrigate crops
to maximize biomass production, though likely at much lower levels than required for row crops.
Two major subtypes of switchgrass that differ in their water use characteristics have been
identified in the wild: an upland and a lowland type. The upland type tends to tolerate dry
conditions, though there is considerable variation in growth characteristics based on
environment, which is likely due to limited crop selection and improvement. The lowland type
requires more water (Parrish and Fike, 2005). Switchgrass farmers may be able to minimize
water use by cultivating the upland type of switchgrass.
Miscanthus appears to be at least as efficient at using water for growth as corn and likely
more so (Beale et al., 1999), though considerable variation exists in the productivity of
Miscanthus based on the identity of the cultivar, where it is grown, and the irrigation regime
(Clifton-Brown et al., 2001; Richter et al., 2008). Published field studies testing Miscanthus in
the U.S. are limited, however, and water use practices have not been established.
3.3.3.2 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 water availability.
Ground water availability, in particular, could be improved in places like Nebraska, where
aquifers provide 85 percent of the water to agriculture (Kenny et al., 2009), if perennial grasses
replace more water-dependent crops (NASS, 2009). Water availability will be minimally
affected in areas requiring little or no irrigation.
3.3.4 Soil Quality
3.3.4.1 Soil Erosion
Both switchgrass and Miscanthus have extensive root systems that prevent the erosion of
soil and, 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 Miscanthus is planted in tilled fields (Heaton et al., 2008;
Parrish and Fike, 2005). This one-time tillage can increase erosion risk, particularly in
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, 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 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 (Blanco-Canqui et al., 2004).
3.3.4.2 Soil Organic Matter
In general, soil organic matter increases more under perennial species 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. The production of both switchgrass and Miscanthus
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can increase soil carbon, but these organic matter benefits are likely to depend on the particular
land use replaced and specific management practices. Where perennials are planted on 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, on such a soil,
switchgrass has been predicted to increase soil carbon by approximately 12 percent following
one decade of production and harvesting (Garten and Wullschleger, 2000). If perennial grasses
replace annual crops, perennials will likely increase soil organic matter, though direct
comparisons are limited (Bransby et al., 1998; Schneckenberger and Kuzyakov, 2007). In one
such study, relative to reported values for corn, soil carbon increased under 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). Soil organic matter accumulation under these
perennials depends, in part, on harvest frequency, and, in the case of switchgrass, on the potential
application of nitrogen fertilizer (Lee et al., 2007b). On the other hand, the effect on soil organic
matter of preparing previously undisturbed land for these biofuel feedstocks has received little
attention to date. Estimates of carbon loss following conventional tilling of undisturbed soils
range from 20 to 40 percent (Davidson and Ackerman, 1993). The amount of time needed for
these perennials to restore soil carbon lost following site preparation is uncertain.
3.3.5 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. Grasses require
significantly less nitrogen fertilizer than corn or soybean, and studies indicate that NOx emissions
should decrease when switchgrass is used as a feedstock (Wu and Wang, 2006). However,
switchgrass is not currently grown on large scales under typical farm conditions. 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). Similarly, switchgrass has been shown to
require lower amounts of phosphorus (P2O5) fertilizer, which translates to lower SO2 emissions
(Wu and Wang, 2006)
As described earlier in Section 3.3.2.3, perennial grasses are expected to require less
pesticide and herbicide than row crops (except when initially establishing perennial grass
plantings); however, 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 switchgrass will involve use of farm
equipment, and thus is expected to generate NOx and PM emissions. However, VOCs and NOx
and PM emissions associated with switchgrass harvesting have been found to be much lower
than those associated with corn harvesting (Hong and Wang, 2009). Decreases in VOCs, CO,
NOx, PM10, PM2.5, and SO2 emissions associated with switchgrass production as compared to
corn or soybean have been reported (Wu and Wang, 2006; Hess et al., 2009).
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3.3.6 Ecosystem Impacts
3.3.6.1 Biodiversity
Models indicate that a greater diversity of birds are supported by switchgrass than by row
crops (corn or soy), though some non-priority species such as horned lark (Eremophila alpestris)
and killdeer (iCharadrius vociferous) may decline (Murray and Best, 2003; Murray et al., 2003).
One study found that perennial grass crops can provide substantially improved habitat for many
forms of native wildlife—including ground flora, small mammals, and bird species—due to the
low intensity of the agricultural management system (Semere and Slater, 2006). 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). 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 contraction of home
ranges to areas near row crops, increasing crop losses and the potential for disease transmission
among wildlife (Walter et al., 2009). Though similar studies for Miscanthus in the U.S. are
lacking, research from the United Kingdom shows that non-crop plants from a wide range of
families (Poaceae, Asteraceae, and Polygonaceae) coexist within young Miscanthus cropping
systems due to a lack of herbicide applications, and support a greater diversity of bird
populations than annual row crops (especially of passerines, game birds, and thrushes) (Bellamy
et al., 2009). These effects are likely to be transient as fields mature and crop height and
coverage become more homogeneous (Bellamy et al., 2009; Fargione et al., 2009). Similar
patterns are likely for the U.S. Use of native mixtures of perennial grasses can restore some
native biodiversity (Tilman et al., 2006).
3.3.6.2 Invasive Plants
Grasses are successful at reproducing, dispersing, and growing under diverse
environmental conditions. This helps explain their dominance across many areas of the globe,
and contributes to their potential risk as agricultural weeds and invasive plants. The risk that
switchgrass or Miscanthus will become an agricultural weed or invasive plant depends on their
specific biology and their interaction with the environments in which they are grown. One study
noted that well-managed biofuel feedstock production must not only prevent feedstock crops
from invading local habitat, but also prevent the crops from genetically invading native species
(Firbank, 2007).
Switchgrass produces large amounts of seed, a trait that correlates with the ability to
spread, though it remains unclear how much and how far switchgrass seed can disperse.
Switchgrass is being bred for vegetative reproduction, tolerance to low fertility soils, and the
ability to grow in dense stands (Parrish and Fike, 2005), all of which could increase invasive
potential. On the other hand, breeding for traits like sterility can be utilized to reduce the risk of
escape and likelihood of negative impacts. For example, hybrid Miscanthus cultivars have been
bred to produce almost no viable seed.
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The location where a feedstock is grown and the interaction between the feedstock and
the local environment will be important for determining its invasion potential. Using species
native to the area they are cultivated minimizes the risk of invasion into natural areas.
Switchgrass is native east of the Rocky Mountains, although a variety could be bred or
engineered to be substantially different from local populations. Switchgrass in any form is not
native west of the Rockies. One risk assessment of introducing switchgrass to California
indicated that it could become invasive relatively easily (Barney and DiTomaso, 2008). The
potential for switchgrass to become a weed of other agricultural crops, even within its native
range, is not known.
Unlike switchgrass, Miscanthus x giganteus (the variety of Miscanthus that has been
tested in Europe as a biofuel feedstock) is not native anywhere in the U.S. Little information
exists about the ability ofM x giganteus to disperse from cultivation and persist as a weed or
invade natural areas. One risk assessment recommended no restrictions on planting in the U.S.
because the plant produces no living seeds and is therefore unlikely to spread easily (Barney and
DiTomaso, 2008). A different study, however, noted that Miscanthus can spread vegetatively and
could undergo genetic changes to produce seeds once more—making it potentially invasive
(Raghu et al., 2006). Miscanthus sinensis has been grown in the U.S. for landscaping and
horticultural purposes. Herbarium specimens and field observations indicate that it can disperse
live seeds and persist in areas beyond where it was originally planted. Miscanthus sinensis, a
species related to Giant Miscanthus, has been grown in the U.S. for landscaping and horticultural
purposes, and is also being developed as a biofuel feedstock. Herbarium specimens and field
observations indicate that it can disperse live seeds and persist in areas beyond where it was
originally planted, including a variety of habitats like pasture, clearcut forests, and residential
areas (Quinn et al., 2010). A recent study found that Miscanthus sinensis spreads quickly enough
to be labeled invasive (Quinn and Stewart, 2010). Some other grass species that have been
considered for use as biofuel currently invade wetlands, including giant reed (Arundo donax)
(Bell, 1997) and reed canary grass (Phalaris arundinacea) (Lavergne and Molofsky, 2004).
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 Miscanthus can
reproduce vegetatively from plant cuttings, both of which may be dispersed during feedstock
transport.
One mitigation option for reducing the potentially negative environmental impacts from
perennial grass production is avoiding cultivation of feedstocks with a history of invasiveness,
especially in places that are climatically similar to where invasion has already occurred. Another
option is to breed feedstocks to limit their dispersal into other fields or natural areas (e.g., the
sterile Miscanthus x giganteus). For instance, sterile, seedless switchgrass cultivars would be less
likely to become invasive than current, seed-bearing cultivars. Often, higher reproduction
correlates with lower biomass, so aggressive breeding programs to increase biomass and
decrease seed production could produce multiple benefits.
Another strategy for managing potential invasiveness is cleaning harvesting machinery
and vehicles used to transport harvested feedstock, which would help to decrease unintended
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Chapter 3: Environmental Impacts of Specific Feedstocks
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.
3.3.7 Assessment
Perennial grasses are likely to require less pesticide, fertilizer, and water than traditional
row crops used for biofuel production (Downing et al., 1995). The benefits of perennial grasses
as a feedstock 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). Use of perennial grasses as a biofuel feedstock
carries many advantages to ecosystem services and to biodiversity relative to traditional row
crops. The magnitude of these advantages depends on resolving some uncertainties and also on
whether perennial grasses are replacing CRP land, row crop farmland, or other lands such as
pasture land, and whether they are grown in a monoculture or in a mixture of species. The
maintenance of landscape-level biodiversity (e.g., including non-cultivated, protected areas
nearby) will depend on the spatial arrangement of reserves promoting connectivity and
population persistence, local management practices, and potential for biofuel crops and their
pests to spread beyond managed boundaries.
3.3.7.1 Key Uncertainties and Unknowns
• Because no commercial-scale facilities exist for converting perennial grasses to
cellulosic ethanol, many uncertainties remain about how growing perennial
grasses as a feedstock will affect environmental conditions when grown at
commercial scales. This holds for all endpoints documented in this report (soil
carbon, leaching, etc.) and highlights the need for large-scale studies comparing
perennial grass cultivated under a variety of management regimes with row crops
and other feedstocks.
• Most existing literature on switchgrass examines the plant's rangeland and
ecological purposes; this literature might not be completely applicable to
switchgrass used as a biofuel feedstock.
• Much genetic potential for both Miscanthus and switchgrass remains to be
explored for increasing their feasibility as feedstocks. If researchers are able to
develop novel cultivars of these plants with significantly improved yields, there
may be less potential for environmental damage from Miscanthus and switchgrass
production.
• Little is known about usage of fertilizer and pesticides for increasing perennial
grass production. The usage of precision management strategies (e.g., minimal
fertilization, irrigation, and pest management at specific times) may potentially
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increase productivity without deleterious ecological impacts. Depending on where
these crops are grown and what crops or other land use they are replacing, they
may improve water quality relative to the previous land use.
• The water requirements of different grass species in different areas of the country
are not documented, and the use and preferred method of irrigation remains to be
determined.
• The role of nitrogen fixation in explaining the productivity of Miscanthus requires
further study and may have large ramifications on the potential use of Miscanthus
as a feedstock.
• The potential invasiveness of switchgrass in the western U.S. and Miscanthus
across all the entire U.S. is relatively unknown. Studies to evaluate feedstocks for
the biological characteristics associated invasiveness, including rate of seed
production, rate and maximum distance of dispersal from field-scale plots, modes
of dispersal (e.g., wind, water, bird), rate of hybridization with already invasive
relatives, resistance to chemical or mechanical control, etc., are crucial for
anticipating and preventing negative impacts and for determining which
alternative feedstocks might pose lower risks.
• 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 includes trees (e.g., removed or "thinned" from forests to reduce fire
hazard or stimulate growth of remaining stands); 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 cultivated in plantation-like settings) and milling residues. Woody biomass
is an attractive energy source because of its widespread availability and capacity to store carbon.
However, to date woody biomass has been of limited use for energy production, with the
exception of pulp and saw mill residues burned to produce heat, steam, and electricity. Woody
biomass has been of particular interest as a biofuel feedstock because some forests might benefit
from thinning and/or residue removal: removing forest residues from forests could reduce the
threat of catastrophic wildfires, at least in some ecosystems, while providing a feedstock for
energy production (Gorte, 2009). No commercial-scale biofuel plants using woody biomass as a
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feedstock are yet in operation, but demonstration and development facilities exist, and woody
biomass is projected to be a future source of cellulosic biofuels.
The U.S. has substantial domestic capacity for producing fuel from woody biomass.
Estimates of the amount of woody biomass available for biofuel production differ widely and
vary by price paid per ton of feedstock. EPA's RFS2 RIA notes that, at $70 per ton, 40 to 118
million dry tons of woody biomass may be available for biofuel production in 2022 (U.S. EPA,
2010b, p. 49). 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 will likely improve in the future.
Under the RFS2 requirements, not all woody biomass would be available. 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,
201 Oh, p. 56). Both forest harvesting residues and thinning operations are expected to be the
predominant sources of woody biomass for future biofuel use, but SRWCs may be important as
well at higher feedstock prices (Perlack et al., 2005; U.S. EPA, 2010b, pp. 38-49; White, 2010).
In the following sections, the potential impacts of harvest residues, thinning, and SRWCs are
discussed in more detail. For comparison purposes, the environmental impacts of SRWCs are
considered in relationship to annual row crops. However, economic analyses suggest that the
most likely sources of land for SRWC plantations are CRP or fallow agricultural lands, rather
than prime agricultural acres or grasslands; therefore, SRWCs are generally unlikely to replace
row crops (Volk et al., 2006; Walsh et al., 2003).
3.4.1.1 Current and Projected Production Areas
The potential sources of woody biomass vary by region of the country, and only SRWC
plantations are likely to result in land use/land cover changes. Forest harvest residues are
produced in major forest harvesting areas, predominantly in places such as the upper Lake States,
the Southeast and the Pacific Northwest (see Figure 3-6). Since these residues will most likely be
collected as a by-product of harvesting operations, the use of forest harvest residues is unlikely to
produce land use/land cover changes (Williams et al., 2009). However, a rise in price paid per
ton for woody biomass may provide an incentive for additional harvesting. Woody biomass from
forest thinning will also occur in major forest harvesting areas, and potentially in areas of high
wildfire risk. In contrast, SRWC plantations can have substantial land use/land cover effects.
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Chapter 3: Environmental Impacts of Specific Feedstocks
1427
1428 Source: Milbrandt, 2005.
1429 Figure 3-6: Estimated Forest Residues by County
1430 3.4.1.2 Overview of Environmental Impacts
1431 Several activities associated with woody biomass as a feedstock may impact the
1432 environment. In the case of forest thinning and residue removal, there may be a direct
1433 environmental impact of biomass removal, as well as an impact from operation of forestry
1434 machinery. In the case of SRWCs, traditional forestry and agricultural activities undertaken
1435 during feedstock cultivation and harvest, such as pesticide, fertilizer, water, and fuel/energy use,
1436 have the potential to impact the environment. In addition, the choice of tree species may
1437 influence the risk of establishment, invasion, and impact during both feedstock production and
1438 transport. All these activities can alter air quality, water quality, water availability, and soil
1439 quality, with resulting impacts on ecosystems, though the extent of the impacts depends on each
1440 activity's intensity.
1441 3.4.2 Water Quality
1442 Use of woody bi omass as a feedstock can impact water quality, primarily through
1443 nutrient runoff and sedimentation. However, the impacts of harvesting trees or removing forest
1444 residues can be limited through implementation of forestry best management practices. The
1445 extent to which SRWCs have a lower water quality impact than conventional crops will depend
1446 on the agricultural intensity of the short rotation woody crops production system (e.g., the extent
Biomass Resources of the United States
Pun»*l Ruhiiiuvft
Pry TMWM/TMf
> ion
SO- XMl
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10 JR
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Mol E it-molcd
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of fertilizer, pesticide use and replanting interval). Table 3-4 shows inputs needed to grow
SRWCs compared to agricultural intensity metrics associated with growing conventional crops.
Table 3-4: Comparison of Agricultural Intensity Metrics for
Short-Rotation Woody Crops and Conventional Crops
Mdric
Reduction Kclc;iii A\cr;iiic
Erosion
12.5 fold
Fertilizer
2.1 fold
Herbicide
4.4 fold
Insecticide
19 fold
Fungicide
39 fold
Source: Ranney and Mann, 1994.
3.4.2.1 Nutrients
The literature is mixed on whether residue removal increases (Kreutzweiser et al., 2008)
or decreases (Lundborg, 1997) nutrient loads to surface water bodies, including wetlands. The
impacts of removing tree harvest residues on nutrient loads vary depending on topography
(slope), soil nutrient content, and the chemistry of the residues themselves (Titus et al., 1997).
Compared to forest residue removal, moderate forest thinning typically does not increase loss of
soil nutrients to ground or surface waters (Baeumler and Zech, 1998; Knight et al., 1991).
Forestry Best Management Practices (BMPs) such as buffer zones (vegetated setbacks
from water bodies) are used to reduce water quality impacts. Careful planning to minimize the
construction of roads and stream crossings or the use of portable stream crossing structures can
help reduce erosion and sedimentation (Aust and Blinn, 2004; Shepard, 2006). Other BMPs
include: using energy efficient machinery, minimizing traffic in buffer zones and choosing low-
impact equipment that is of the appropriate size and scope for the site (Phillips et al., 2000). The
draft 2010 National Report on Sustainable Forests by USDA's U.S. Forest Service suggests
widespread adoption of forestry BMPs to protect water resources, although many states failed to
respond to a request for data (U.S. Forest Service, 2010). If practices are followed, impacts can
be minimized; outreach, education, and monitoring to ensure implementation and effectiveness
are ongoing.
As described above, SRWCs are unlikely to directly replace row crops; however, for
comparative purposes, it is noted that nutrient losses from SRWCs are in general considerably
less than in annually cropped systems, depending in part on the harvesting and replanting
interval. In willow plantations, the recommended fertilization rate is 89 pounds of nitrogen per
acre (100 kg/hectare) every 3 years, which equates on an annual basis to approximately 22
percent of the average rate for corn production (Keoleian and Volk, 2005; NASS, 2006). In the
first year or two following planting, SRWC plantations can exhibit losses of nitrogen at rates
comparable to conventional grain production, yet following this initial 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 a native forest
found no difference (Perry et al., 1998), and measurements of nitrogen in ground water and
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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 aboveground 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.
3.4.2.2 Sediment
Forest soils generally exhibit low erosion rates and thus small sediment losses to surface
waterways (Neary et al., 2009). However, when forests are harvested and the soil prepared for
the next stand without using BMPs, erosion rates can increase significantly (McBroom et al.,
2008). 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, removal of
harvest residues is an element of harvest operations that could increase erosion and associated
sediment loading to surface waters, especially on steeper slopes (Edeso et al., 1999). Thinning
can also increase erosion and sediment loads to surface waters, depending on the site
characteristics and the methods used (Cram et al., 2007; U.S. Forest Service, 2005; Whicker et
al., 2008). Research indicates that proper use of BMPs, such as road design and buffer zones, can
significantly reduce sediment impacts to surface waters (Aust and Blinn, 2004; Shepard, 2006).
In addition, erosion rates at harvested sites decline once vegetation re-colonizes the site (Aust et
al., 1991; Miller et al., 1988). See Section 3.4.4.1 for discussion of impacts of SRWCs on soil
erosion and sedimentation.
3.4.2.3 Pesticides
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 (Ranney and Mann,
1994).
3.4.3 Water Quantity
3.4.3.1 Water Use
The utilization 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
evapotranspiration rate. In places where high-intensity tree plantations replace existing
ecosystems with lower evapotranspiration rates, the potential for increased water consumption is
significant. A study of southern pine in the Southeast found that an additional 865 gallons of
water is consumed per gallon of ethanol produced from woody biomass (roughly 1,300 gallons
of water per gallon of gasoline equivalent), due to land conversion for woody biomass
production (Evans and Cohen, 2009). Further, in certain locations and in some years, additional
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irrigation water may be required to maintain high biomass accumulation (Hansen, 1988).
Precision application systems can reduce the amount of water applied.
3.4.3.2 Water Availability
Use of forest harvest residues and biomass from thinning should have little or no effect
on water availability at the feedstock production stage. 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 could reduce or eliminate stream flow (Jackson et
al., 2005). In places with seasonal flooding, modulation of surface water flow closer to pre-
agricultural development levels could possibly mitigate flooding (Perry et al., 2001).
3.4.4 Soil Quality
3.4.4.1 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. Short-rotation woody crops
require intensive soil preparation for successful establishment, and it is during this brief
establishment phase that erosion rates can be a high (Keoleian and Volk, 2005). For example,
higher sediment losses were observed within the first 3 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). However, in established
SRWC plantations, soil erosion rates are likely much lower than those of annually harvested row
crops. 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 3-
to 4-year intervals for a total of 7 to 10 harvests (Keoleian and Volk, 2005). This allows 21 to 40
years between soil disturbances.
3.4.4.2 Soil Organic Matter
Harvesting of forest residues removes plant material that could otherwise become soil
organic matter. A review analysis suggested that, on average, a complete, one-time removal of
forest residues slightly decreases soil organic matter in coniferous forests, but may not affect
levels in hardwood or mixed stands (Johnson and Curtis, 2001). Leaving logging residues is
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). Further
research is needed to determine the cumulative effect of repeated removals. Thinning of forests
has been shown to reduce carbon in forest floor layers, but less evidence is available regarding
its impact on mineral soil organic matter levels (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.
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Production of SRWCs can add organic matter to the soil, sequestering carbon, but the net
soil organic matter benefits of these crops depend on land-use change and time between harvests.
Generally, soil organic matter, including carbon, is initially lost when a forest is planted because
the amount of organic matter entering the soil from the reestablishing plants is typically small
and is exceeded by decomposition (Paul et al., 2002). Over time, substantial amounts of organic
matter accumulate in the trees, the forest floor layer and the soil, greatly exceeding the carbon
contained in abandoned agricultural systems (Schiffman and Johnson 1989; Huntington 1995;
Richter et al., 1999). The amount of time it takes for soil carbon to re-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 those 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). Overall, if
frequently harvested SRWCs replace longer rotation, managed forest lands, then the net effect on
soil organic matter is likely to be negative; but, if they are grown using longer rotations,
particularly on degraded former agricultural land, substantial amounts of organic matter are
likely to added to the soil (Schiffman and Johnson, 1989; Huntington 1995).
3.4.4.3 Soil Nutrients
Use of harvesting residues removes a potential source of soil nutrients that can be utilized
by the regenerating forest. Harvesting with residue removal generally leads 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). The cumulative effects of repeated
removals from the same site are likely negative, but require further study. Residue removal has
been suggested as a management technique to reduce nitrogen in forests that receive high
atmospheric deposition, such as in the northeastern U.S. (Fenn et al., 1998). However, this may
lead to depletion of calcium and other nutrients critical for plant growth (Federer et al., 1989).
Overall, residue removal may be less problematic on high fertility soils compared to coarser-
textured, low fertility soils. The risk posed to soil nutrients by thinning is likely to be much
smaller than that of the removal of harvesting residues (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 may 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.
3.4.5 Air Quality
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 (reducing emissions associated with fertilizer production and
application). However, some species such as poplar and willow that are potential feedstocks for
either cellulosic ethanol or biodiesel are significant emitters of biogenic VOCs such as isoprene.
Compared to non-woody crops that emit relatively little isoprene, extensive plantations of these
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1600 trees have the potential to significantly impact ozone concentrations, although this effect will be
1601 highly sensitive to environmental conditions, preexisting vegetative cover, and the presence of
1602 other atmospheric chemicals, especially NOx (Hess et al., 2009; U.S. EPA, 2006b).
1603 3.4.6 Ecosystem Impacts
1604 3.4.6.1 Biodiversity
1605 Tree harvesting activities can impact aquatic biodiversity in a number of ways. For
1606 example, removal of woody biomass by harvesting of forest residues or thinning in riparian areas
1607 may reduce the woody debris in headwater streams, which is an important component for aquatic
1608 habitat (Angermeier and Karr, 1984; Chen and Wei, 2008; Stout et al., 1993; Thornton et al.,
1609 2000). In addition, tree canopies over streams help maintain cooler water temperatures conducive
1610 to cold-water smallmouth bass, trout, or salmon populations (Binkley and Brown, 1993; U.S.
1611 EPA, 2006c). These benefits may be lost when trees are harvested.
1612 There is some evidence that planting SRWCs can improve species habitat relative to
1613 agricultural crops (Christian et al., 1998). Several studies have documented that bird species
1614 diversity on woody biomass plantations is comparable to that of natural shrubland and forest
1615 habitats (Dhondt et al., 2007; Perttu, 1995; Volk et al., 2006), though this is not always the case
1616 (Christian et al., 1998). Bird and small mammal species found on SRWC plantations tend to be
1617 habitat generalists that can also use open habitats like agricultural lands, while birds and small
1618 mammal species in mature forests are more specialized and require forest cover (Christian et al.,
1619 1998). If understory plants become prevalent in SRWC plantations, species diversity can
1620 increase due to increases in habitat complexity (Christian et al., 1998).
1621 3.4.6.2 Invasive Plants
1622 Like perennial grasses, woody plants cultivated for biofuel feedstock can become
1623 invasive. However, because many woody plants have a longer life cycle than many (though not
1624 all) grasses, they tend to reproduce and spread more slowly, making the evidence of their
1625 invasion and effects on natural areas less immediate. Trees used in forestry can sometimes be
1626 highly invasive, negatively affecting biodiversity and water availability (Richardson, 1998).
1627 Proposed SRWCs, such as willow or poplar, are native or hybrids of natives in the U.S.,
1628 but Eucalyptus species, which are non-native, may pose an invasive risk. Eucalyptus is an
1629 important genus of forestry plants worldwide, and its future development as a biofuel feedstock
1630 in plantations has been discussed for Florida (Rockwood et al., 2008). Several species of
1631 Eucalyptus, including E. globulus and E. grandis, have been introduced to Florida and bred
1632 conventionally and using biotechnology for traits like cold tolerance. The intent is to expand
1633 their future cultivated range to include much of the Southeast. While introduced Eucalyptus or
1634 their improved varieties have not become invasive in the Southeast, E. globulus is a listed
1635 invasive plant in California, and recently, several cultivars of E. grandis were found to be
1636 potentially invasive by the Institute of Food and Agricultural Science at the University of Florida
1637 and are recommended for planting only under limited conditions. Reassessment of the species
1638 will take place again in two years after continued monitoring for invasion.
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3.4.7 Assessment
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 biofuels made
from woody biomass is substantial, with predominant sources coming from forest harvest
residues, thinning, and SRWCs. Of these, the removal of harvesting residues from logging sites
is likely to have the most negative impacts on soil and water quality. Complete removal of
residues poses the risk of increased nutrient and sediment losses to waterways, and decreased
plant nutrient availability and forest productivity. In comparison, moderate thinning regimes will
have relatively few impacts on soil and water quality, particularly on stable slopes and finer-
textured soils.
The environmental effects of SRWCs as a source of woody biomass are more complex,
since these require a shift in land use/land cover type. In general, SRWCs are expected to result
in lower nutrient and sediment loads to surface waters relative to that of row crops, especially
once the canopy is established. Woody biomass species require fewer inputs of fertilizer and
pesticides, resulting in reduced runoff of these substances into surface and ground water. Woody
biomass production requires considerable water use, but if undertaken in appropriate regions
with adequate water supplies, water quality benefits may outweigh possible water availability
drawbacks.
3.4.7.1 Key Uncertainties and Unknowns
• Woody biomass is not yet converted to biofuel on a large-scale; this creates
considerable unknowns and uncertainties when projecting the potential
environmental effects, both positive and negative, of this feedstock.
• Specific environmental impacts will vary, depending on soil type, soil chemistry,
topography, climate, and other factors (e.g., the land use SRWCs would replace).
• 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 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. For example, it is not known whether repeated
removal of biomass from SRWCs will deplete soil nutrients over the long term,
particularly on marginal soils.
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3.5 Algae
3.5.1 Introduction
Algae are of interest as a biofuel feedstock because of their high oil content, low water
demand, ability to recycle waste streams from other processes, and ability to grow on marginal
lands (EPA, 2010b). Algae production demands much less land area per gallon of fuel produced
compared to most other feedstocks.
Research and pilot studies have shown that the lipids and carbohydrates in microalgae19
can be refined and distilled into a variety of biodiesel- and alcohol-based fuels, including diesel,
ethanol, methanol, butanol, and gasoline. 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 algal use as
biofuel.
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 utilize 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). 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, 2010b).
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 (NRDC, 2009). After harvesting, the biofuel production process begins
when oil is extracted from the algae through chemical, mechanical, or electrical processes (U.S.
EPA, 2010b, p. 61). Algal oil can then be refined with the same transesterification process used
for other biofuel feedstocks such as soybeans.
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.
19 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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3.5.1.1 Current and Projected Cultivation
Land use consideration is one of the primary drivers behind interest in algae as a biomass
feedstock. Relative to other feedstock resources, algal biomass has significantly higher
productivity per cultivated acre. For example, meeting half the current U.S. transport fuel
demand with soybean-based biodiesel would require an arable land area in excess of 300 percent
of the area of all 2007 U.S. cropland, while the land area required to meet those same fuel needs
using algal biodiesel would be less than 3 percent of all U.S. cropland in 2007 (Chisti, 2007).
Moreover, algae cultivation does not require arable land. 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).
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 economic 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, 2010b). 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).
3.5.1.2 Overview of Environmental Impacts
Algae-based biofuel production systems are still being investigated at the pilot stage
using smaller-scale prototype research facilities. Evaluating the potential environmental and
resource impacts of full-scale production is 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 not a concern.) In addition to these impacts, there is potential for invasive algae strains to
escape from cultivation (NRDC, 2009). 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.
3.5.2 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
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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. According to the National
Resources Defense Council, wastewater from the dewatering stages of algae production could be
released directly, sent to a treatment unit and released, or recycled back as make up water,
depending on the process (NRDC, 2009). Depending on the treatment requirements, release of
wastewater could potentially introduce chemicals, nutrients, additives (e.g., from flocculation),
and algae, including non-native species, into receiving waters.
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). By co-locating these facilities, 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 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).
3.5.3 Water Quantity
3.5.3.1 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. Estimates for
water consumption vary widely, ranging from 25 to 974 gallons of water per gallon of biodiesel
produced (U.S. EPA, 2010b). EPA has estimated that an open-system-type biofuel facility
generating 10 million gallons of biofuel each year would use between 2,710 and 9,740 million
gallons of saline water each year; a similar scale photobioreactor-type facility would use between
250 and 720 million gallons of saline water annually (U.S. EPA, 2010b, Table 2.4-56, p. 426).
The harvesting and extraction processes also require water, but data on specific water
needs for these steps are limited (U.S. EPA, 2010b). Compared to the water required for algae
growth, however, demands are expected to be much lower.
3.5.3.2 Water Availability
Depending on the cultivation system, 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 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 (U.S. EPA, 2010b), as well as in contaminated wastewater such as agricultural,
animal, or municipal effluent; or even coal, pharmaceutical, or metal plating wastewater (NRDC,
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1796 2009). Thus, competition for freshwater resources may be mitigated by siting facilities in areas
1797 that can provide suitable brackish or wastewater sources.
1798 In addition to the water quality benefits described above, co-locating algae production
1799 facilities with wastewater treatment plants can reduce water demands (Clarens et al., 2010). The
1800 water availability impacts of algae production for biofuel can also be mitigated in large part
1801 using photobioreactors, which require less water and land area than open systems (U.S. EPA,
1802 2010b, Table 2.4-56, p. 426).
1803 3.5.4 Soil Quality
1804 Very little peer-reviewed literature exists on the soil impacts of algae production because
1805 these impacts are likely to be negligible and have therefore not been the subject of much study.
1806 Presumably, the primary mechanism affecting soil quality would be transport and migration into
1807 soil of wastewater, particularly highly salinated wastewater, that has been released into
1808 freshwater ecosystems (NRDC, 2009).
1809 3.5.5 Air Quality
1810 The effects of algae-based biofuels on air quality have received little attention to date in
1811 peer-reviewed literature. As a result, additional research is needed to determine whether anything
1812 unique to algae production processes would raise concern about air emissions.
1813 Open or hybrid open systems appear to have greater potential to impact air quality
1814 compared to enclosed photobioreactors, given the highly controlled nature of the latter systems.
1815 No studies are yet available, however, to characterize or quantify emissions associated with open
1816 systems used to produce algae for biofuel. Studies have measured air emissions of open-system
1817 algae ponds that are part of wastewater treatment systems (Van der Steen et al., 2003), but these
1818 studies may have very limited applicability to open systems for commercial-scale production of
1819 algae oil for biodiesel. Additional research will be required to estimate and characterize
1820 emissions from pumping, circulation, dewatering, and other equipment used to produce algae for
1821 biofuel.
1822 3.5.6 Ecosystem Impacts
1823 3.5.6.1 Biodiversity
1824 Algal production has fewer biodiversity impacts than production of other feedstocks
1825 because algae typically require less fertilizer, pesticide, and water than do other feedstocks, and
1826 because algal production plants may be co-located with wastewater treatment plants. As
1827 mentioned above, the location of algae production facilities will be a key factor affecting the
1828 potential for impacts. Using wastewater to capture nutrients for algal growth could help reduce
1829 nutrient inputs to surface waters (Rittmann, 2008). Algae also require low inputs of fertilizers
1830 and pesticides compared to other feedstocks, which may translate into fewer ecological impacts
1831 to aquatic ecosystems (Groom et al., 2008). Production facilities for algae that need sunlight to
1832 grow could be located in arid regions with ample sunlight (Rittmann, 2008); however, growing
1833 algae in areas with limited water resources could impact the amount of water available for the
1834 ecosystem because of draws on ground water. It is unknown what impacts an accidental algae
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release might have on native aquatic ecosystems, particularly if the algae released have been
artificially selected or genetically engineered to be highly productive and possibly adaptable to a
range of conditions.
3.5.6.2 Invasive Algae
The potential for biofuel algae to be released into and survive and proliferate in the
environment is, at present, highly uncertain. This potential will vary, depending 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, near and far. Designers of coastal
algae production plants must take into account hurricanes and other severe storms that could
disperse algae over large areas. Wildlife, including birds, may also disperse algae. 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 some, but not all, strains with the most desirable
commercial characteristics would be out-competed by native algae (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.
3.5.7 Assessment
3.5.7.1 Current and Future Impacts
With the exception of nutrients, open system cultivation requires far more resources than
photobioreactor systems. Regardless which type of system is used commercially, future increases
in production of algal biomass have the potential to impact water availability and quality, air
quality and atmospheric climate, and ecosystem health and biodiversity. However, due to the
lack of data on commercial-scale algal biofuel production processes, it is uncertain what these
impacts will be.
In some cases, the algal production process could prove environmentally beneficial. For
example, use of wastewater effluent, particularly partially treated wastewater, to cultivate algae
provides benefits of removing nutrients from the wastewater and reduces the environmental
impact of the production process. Combining commercial-scale algae production facilities with
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wastewater treatment plants may therefore create synergies that increase algae yields while
decreasing environmental impacts of both facilities.
Key points to understanding the potential environmental impacts of using algae for
biofuel production are described below.
Water Quality: The water quality impacts of algal biofuel production will depend on both
the source of water used for cultivation and the quality of the water released from the production
facility. Algae production facilities co-located with water treatment plants, fossil fuel power
plants, or other industrial sources of pollution could have a positive impact on water quality.
However, release of wastewater from an algal biofuel production process—especially salinated
wastewater released into a freshwater environment—could adversely affect water quality.
Water Quantity: Water is an important input in the algae cultivation process; increased
production of algal biofuels will impact water availability, especially in areas where water is
already scarce. However, algae may be less water intensive than other feedstocks. Moreover,
because algae can thrive in brackish and untreated waters, they are an ideal feedstock for water-
stressed locations.
Soil Quality: Soil quality impacts are likely to be minimal, based on existing studies.
Air Quality: Little is known about how algal biofuel production will affect air quality.
However, preliminary data suggest that open system cultivation systems have a greater potential
than photobioreactor systems to adversely affect air quality.
Ecosystem Health/Biodiversity: Little is known about how increases in algal biofuel
production might affect biodiversity. Because algae demands substantial amounts of water, its
cultivation could adversely impact native species in water-stressed locations. Compared with
other feedstocks, however, algae is not water intensive. Also unknown are what impacts an
accidental release of algae might have on native aquatic ecosystems. Algae require low inputs of
fertilizers and pesticides compared to other feedstocks, which may also translate into fewer
ecological impacts to aquatic ecosystems
Invasive Species: 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.
3.5.7.2 Key Uncertainties and Unknowns
• 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.
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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. In some instances, diverting waste that cannot be recycled or reused to fuel has been
found to reduce land-filled materials by 90 percent, helping to also extend the lifetime capacity
of the landfill (Helou et al., 2010).
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
20
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 municipal solid waste (paper, wood, yard trimmings, textiles, and
other materials that are not plastic- or rubber-based), has the potential to be a significant
feedstock for ethanol and other biofuels. Using 2005 data, the U.S. Energy Information
Administration calculated that 94 million tons (MT) (about 56 percent) of the 167.8 MT of MSW
waste generated that year had biogenic BTU content (EIA, 2007). This estimate included food
waste (the third largest component by weight), which is also potentially viable as a biofuel
feedstock in addition to biogenic material listed above. Some producers claim to have
thermochemically-based technology that can yield 120 gallons of ethanol per ton of MSW, and
therefore, this could serve as a rough MSW yield estimate. (Fulcrum Bioenergy, 2009).
Accepting this estimate, the 94 MT of biogenic MSW generated in the U.S. in 2005 would have
the potential to generate up to 11 billion gallons of ethanol. 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
20 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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Chapter 3: Environmental Impacts of Specific Feedstocks
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; Helou et al., 2010).
The U.S. Department of Energy 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 U.S. 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 a biofuel feedstocks.
The U.S. generates over 1 billion tons of manure, biosolids, and industrial by-products
each year (ARS, n.d.). The amount of manure generated at confined and other types of animal
feeding operations in the U.S. 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 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 [MMTCE] [3.0 teragrams, or Tg] 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 has potential to create a
higher value use with significant environmental and economic benefits.
3.6.4 Environmental Impacts of Waste-Based Biofuel
Waste-based biofuels are expected to have both environmental benefits and impacts. On
the positive side, for example, diverting waste from landfills avoids generation of landfill
methane gases, and diverting waste and trap greases from wastewater treatment plants helps
avoid costly plant upsets that contribute to combined sewer overflow. Biorefineries that use
wastes, particularly MSW, tend to be located in proximity to the waste source, which correlates
well with the densely populated end-users of transportation fuels and helps reduce the GHG
lifecycle 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,
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Chapter 3: Environmental Impacts of Specific Feedstocks
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.
Assessment 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.
3.7.1 Forests
Woody biomass is the feedstock most likely to affect forests; row crops, algae, and most
perennial grasses are unlikely to have an impact on this habitat.
Section 21 l(o) of the Clean Air Act limits planting of short-rotation woody crops and
harvesting of tree residue to actively managed tree plantations on non-federal land that was
cleared prior to December 19, 2007, or to non-federal forestlands; and limits removal of slash
and pre-commercial thinning to non-federal forestlands. However, as described in Table 3-5, a
variety of activities associated with producing woody biomass feedstock may impact forests.
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Chapter 3: Environmental Impacts of Specific Feedstocks
Table 3-5: Overview of Impacts on Forests from Different Types of Biofuel Feedstocks
IVedslnck
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Section
Row Crops
Unlikely to have impacts.
Perennial
Grasses
Most grass species are unlikely to have impacts.
3.3.6.2
Woody
Biomass
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.
3.4.4.3
SRWC plantations can sustain high species diversity, although bird and mammal
species tend to be habitat generalists.
3.4.5.1
Some tree species under consideration, like Eucalyptus, may invade forests in certain
locations.
3.4.5.2
Harvesting forest residues may decrease nutrient availability, soil organic matter,
and woody debris available for species habitat.
3.4.4.2;
3.4.4.3;
3.4.6.1
Algae
Unlikely to have impacts.
3.7.2 Grasslands
Production of row crops and perennial grasses for biofuel feedstocks can impact
grasslands, although perennial grasses may also have some positive effects on grasslands.
In addition to the restrictions on forested sources of renewable biomass mentioned above,
Section 21 l(o) of the Clean Air Act more broadly limits the lands on which any biofuel
feedstock can be produced to those that were cleared or cultivated at any time prior to December
19, 2007, either in active management or fallow and non-forested. Therefore, grassland that
remained uncultivated as of December 19, 2007, may not be converted to grow biofuel. Most of
lands that would be eligible for renewable biomass production under the Clean Air Act, because
they were cultivated at some point prior to December 19, 2007, are now part of the Conservation
Reserve Program (see Section 3.2.1.1). The USDA estimates that the vast majority (78 percent)
of lands that will be taken out of the CRP to grown biofuel feedstock will be grasslands (FSA,
2008). Therefore, conversion of CRP lands to grow biofuels will impact grassland ecosystems, as
will other aspects of biofuel feedstock production (Table 3-6).
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Chapter 3: Environmental Impacts of Specific Feedstocks
Table 3-6: Overview of Impacts on Grasslands from Different Types of Biofuel Feedstocks
Tccdslnck
(•riissliinds Impiicl
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Section
Row Crops
Conversion of grasslands to row crops impacts grassland-obligate species, potentially
leading to declines, including declines in duck species.
3.2.6.1
Higher proportions of corn within grassland ecosystems leads to fewer grassland bird
species.
3.2.6.1
Perennial
Grasses
Conversion of row crops to switchgrass may improve grassland habitat for some species
depending on management regimes.
3.3.6.1
Conversion of CRP lands to perennial grasses or harvesting of existing grasslands is
less likely to have negative impacts on grassland species, particularly if harvesting
occurs after the breeding season.
Use of native mixtures of perennial grasses can restore some native biodiversity.
3.3.6.1
Cultivation of switchgrass outside its native range may lead to invasions of native
grasslands.
3.3.6.2
Cultivation of Miscanthus may lead to invasions of pasture and other grasslands.
3.3.6.2
Woody
Biomass
Unlikely to have impacts.
Algae
Depends on siting.
2034
2035 3.7.3 Impacts on Wetlands
2036 Provisions in both the Food Security Act of 1985 (commonly known as the Swampbuster
2037 Program) and Clean Water Act (Section 404 Regulatory Program) offer disincentives that limit
2038 the conversion and use of wetlands for agricultural production. Nevertheless, impacts to wetlands
2039 are still expected from the feedstocks assessed in this report (Table 3-7).
Table 3-7: Overview of Impacts on Wetlands from Different Types of Biofuel Feedstocks
l-ccdslock
Wclliinds Impiicl
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Section
Row Crops
Increased sediment, nutrients, chemicals, and pathogens from runoff flow into
downstream wetlands.
3.2.2
Increased nutrient loadings, leading to changes in wetlands community structure.
3.2.2.1
Perennial
Grasses
Reduced sediment and nutrient loadings, leading to improved water quality (but
dependant on specific management practice).
3.3.2.1
Some grass species under consideration may invade wetlands, including giant reed
(Arundo donax) and reed canary grass (Phalaris arundinacea).
3.3.6.2
Woody
Biomass
Harvesting forest residues and thinning may increase nutrient loads, depending on
slopes, soils, any buffer zones, and use of best management practices to reduce runoff.
3.4.2.1
Algae
Algal strains created may escape from cultivation and invade wetlands. As noted in
Section 3.5.2, use of algae for biofuel may also have positive impacts: 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 would otherwise contribute to thermal pollution, while reducing freshwater
demands and fertilizer inputs.
3.5.6.2
2040
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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 U.S. established a coordinated framework for regulatory oversight in
1986 (OSTP, 1986). Since then, the relevant agencies (EPA, USD A, and 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 (Craig et al., 2008; Auer, 2008; Nickson, 2008; Romeis et al., 2008;
Raybould, 2007; Andow and Zwalen, 2006; Conner et al., 2003; Pollard et al., 2004). This
section describes 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.
As indicated earlier in this chapter, great advantage has already been taken for genetically
engineered corn and soybean, which are now grown worldwide, along with other engineered
crops. Brookes and Barfoot have conducted a series of extensive post-commercialization
assessments of genetically engineered maize, soybeans, cotton, sugar beets, and canola varieties
at 10-year intervals (Brookes and Barfoot, 2006, 2008, 2009, 2010). 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 independently
are consistent with the general trends (Brookes and Barfoot, 2010). Assuming that current
genetically engineered varieties of corn and 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 biorefinery 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 (Wolt, 2009; Chapotin and Wolt, 2007; Wilkinson and
Teper, 2009; Firbank 2007; Lee et al. 2009). For example, some first attempts have been made at
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Chapter 3: Environmental Impacts of Specific Feedstocks
2084 evaluating feedstocks with particular traits; suggestions for minimizing environmental impacts
2085 are incorporated (Kausch et al., 2010a, 2010b).
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Chapter 4: Biofuel Production, Transport, Storage and End Use
1 4. Biofuel Production, Transport, Storage and End Use
2 4.1 Introduction
3 This chapter addresses potential environmental impacts of post-harvest activities of the
4 biofuel supply chain (see Figure 4-1). These activities comprise feedstock logistics (discussed in
5 Section 4.2) and biofuel production (Section 4.3), distribution (Section 4.4), and end use (Section
6 4.5).
7 Production of biofuel from feedstock takes place at biofuel production facilities through a
8 variety of conversion processes. The resulting biofuel is transported to blending terminals and
9 retail outlets by a variety of means, including rail, barge, tankers, and trucks. Biofuel distribution
10 almost always includes periods of storage. Once dispensed at the final outlet, biofuel is
11 combusted in vehicles and other types of engines, usually as a blend with gasoline or diesel, or in
12 some cases in neat form.
13 Biofuel production, distribution, and end use result primarily in impacts to air and water.
14 Air emissions may be released by a variety of sources (see Figure 4-1). Many factors affect the
15 quantity and characteristics of these emissions, including the type and age of equipment used,
16 and operating practices and conditions.
Emissions from:
• Farm equipment
• Transportation (rail,
« Combustion of fuels
• Exhaust from
• Exhaust
* Fertilizer& pesticide
truck) vehicle exhaust
(gas, coal, electricity)
transportation vehicles
• Evaporation
production &
* Production of fuels
used in the production
(rail, barge, tankers,
application
used in transport
facility
trucks)
• Electricity generation
• Methane emissions
• Exhaust from pipeline
for pumping irrigation
from wastewater
pumps
water& drying grain
treatment plants
• Production of fuels
* Fugitive dust
used in transport
• Evaporation from
handling, spills & leaks
• Permeation emissions
i
1
¦
Feedstock
Production
• Land Use/
Conversion
• Feedstock
Cultivation &
Harvest
i
1
1
1
Feedstock
Logistics
Transport, Storage &
Distribution
i
i
i
i
Biofuel
Production
Conversion of
Feedstock to
Biofuel
4
¦
Biofuel
Distribution
Handling, Blending,
Transport & Storage
1
1
1
¦
Biofuel Use
Vehicle Fueling &
Operation
17
18 Figure 4-1: Sources of Criteria Air Pollutant and Toxics Emissions Associated with
19 Production and Use of Biofuel
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Chapter 4: Biofuel Production, Transport, Storage and End Use
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 may require 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 groundwater during biofuel handling,
transport, and storage. Additionally, phosphorus runoff from the manure of animals that have
been fed an ethanol by-product, dried distillers grains with solubles, which has a high
phosphorus content (Regassa et al., 2008), may have the potential to impact water quality.
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
the impacts of corn ethanol and diesel from soybean, since these constitute the vast majority of
biofuel produced and used in the U.S. 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. The most
significant environmental impacts of these activities are the emissions associated with energy
use. Both greenhouse gases (GHG) 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 are transported from fields to the drying site, storehouse, or
collection center, followed by transport to the biodiesel refinery. Air quality may be affected by
emissions from the combustion of fuels used for transportation vehicles and equipment.
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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 U.S. with a
21
combined capacity of 12 billion gallons per year (bgy) (U.S. EPA, 2010b, footnote 250). At
that time, 27 of these (representing 1,400 million gallons per year (mgy) of capacity) were idled,
and another 10 facilities, with a combined capacity of 1,301 mgy, were under construction (U.S.
EPA, 2010b, p. 137). These facilities are located in the major corn-producing region of the
country: Iowa (the largest production capacity and the greatest number of plants) followed by
Nebraska, Minnesota, Indiana, and Illinois (U.S. EPA, 2010b).
Conventional ethanol is produced from the fermentation of corn starch. Two methods are
currently utilized:
• 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.
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.
21 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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• 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 comprised 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, and to demonstration plant construction. Although no U.S.
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 U.S., with
a combined capacity of 2.8 billion gallons per year (bgy) (U.S. EPA, 2010b). 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, rape, palm, 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, comprising an
estimated 10 percent of the final product (U.S. EPA, 2010b). Table 4-1, below shows the
breakdown of feedstocks used to produce biodiesel in the U.S. in 2009. Soybean oil made up the
majority of biodiesel feedstock, comprising 54 percent.
Table 4-1. 2009 Summary of Inputs to U.S. Biodiesel Production
111 pill
2009 Total (lbs.)
Percentage ol* Total
Feedstock Inputs
Vegetable Oils
Corn Oil
84
2.3%
Soybean Oil
1,974
54.0%
Other
Vegetable Oil
7
0.2%
Animal Fats
Poultry Fat
127
3.5%
Tallow
524
14.3%
Animal Fats
White Grease
307
8.4%
Other Animal
Fats
82
2.2%
Recycled
Feedstock
Yellow Grease
156
4.3%
Other
Recycled
Feedstock
13
0.4%
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Table 4-1. 2009 Summary of Inputs to U.S. Biodiesel Production
111 pill
2009 Total (lbs.)
Percentage ol* Total
Other Inputs
Alcohol
328
9.0%
Catalysts
56
1.5%
Source: EI A, 2010
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, 2010b). 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 algal 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 utilize seed oils
or animal fats to produce an isoparaffin-rich diesel substitute referred to as "green diesel" or
renewable diesel (Huo et al., 2008).
Although the transesterification process can generate a much larger amount of diesel
product than the other processes, as noted above, it requires more energy and chemical inputs
(Huo et al., 2008). In the case of biodiesel hydro-generation technology, inputs such as
hydrogen, which are very energy-intensive to produce, must 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).
4.3.2 Air Quality
Air quality impacts associated with the production of biofuels occur throughout the
production chain (Figure 4-1). EPA's Regulatory Impact Analysis (RIA) of the revisions to the
national Renewable Fuel Standard Program (RFS2) assessed the air pollutant emissions and air
quality impacts of the biofuel volumes (see Table 2-1 in Chapter 2) required under the 2007
Energy Independence and Security Act (EISA). The discussion below summarizes the RIA
results; the interested reader is referred to the RIA for additional details (U.S. EPA, 2010b).
22 23
The RIA analysis ' focused on the projected impact of the renewable fuel volumes
required in 2022, and accounted for GHG life cycle emissions, as well as the displaced
petroleum consumption associated with use of biofuels. The emission impacts of the 2022 RFS2
22 The RIA's assessment of air quality relied on data from the EPA's 2005 National Emissions Inventory,
supplemented with the most up-to-date information where possible.
23 For assessment of electrical energy demand, the RIA used a national energy source profile (i.e., coal, hydro, wind,
natural gas) rather than regional source profiles, which can vary across the country.
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volumes 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. The RIA analysis found decreases in overall emissions
for carbon monoxide (CO) and benzene, and increases in overall emissions for nitrogen oxide
(NOx), volatile organic compounds (VOCs), PM, and several air toxics, especially ethanol and
acetaldehyde. Overall emissions of sulfur dioxide (SO2) exhibited mixed results, depending on
the fuel effect specified.
For biofuel production and distribution, the net change in VOC, CO, NOx, and PM
emissions can be attributed to two effects: 1) emission increases connected with biofuel
production, and 2) emission decreases associated with reductions in gasoline production and
distribution as ethanol displaces gasoline. Increases in fine particles less than 2.5 micrometers in
diameter (PM2.5), sulfur oxide (SOx), and especially NOx were determined to be driven by
stationary combustion emissions from the substantial increase in corn and cellulosic ethanol
production. Substantial fugitive dust and particulate increases are also associated
with agricultural operations.
The RIA found that increasing the production and distribution of ethanol would 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 U.S. Emissions of ammonia are expected to increase
substantially due to increased ammonia from fertilizer use. Additional details on EPA's analysis
of changes in emissions associated with the RFS2 volumes can be found in
www. epa. gov/otaq/fuel s/renewabl efuel s/regul ati on s. 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, utilize dry mill technology (Wang et al., 2007a).
Because most ethanol plants utilize similar dry milling production processes, differences in
environmental impacts among plants are primarily due to each plant's choice of fuel. EPA's RIA
assumes a dry mill for the base scenario.
EPA's 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 or
biogas, 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 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 greenhouse gas emissions and other possible environmental impacts (since drying
distillers grains is an energy-intensive process).
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4.3.2.1 Ethanol
Ethanol production requires electricity and the use of steam. Electricity is either
purchased from the grid or produced onsite, and steam is typically produced onsite 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, 2010b; 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 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, 2010b). Ethanol vapor and air toxic
emissions associated with biofuel production were projected to increase in EPA's RFS2 RIA, but
these would be very small compared to current emissions (U.S. EPA, 2010b).
4.3.2.2 Biodiesel
While the production process for biodiesel is fundamentally different from ethanol,
thermal and electrical energy are still required 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 those 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., 2009).
4.3.2.3 Greenhouse Gases
Fuel combustion at ethanol and biodiesel facilities releases greenhouse gases.
Fermentation to ethanol also releases CO2. Combustion-related greenhouse gas emissions are
released to the atmosphere, but some ethanol facilities capture, purify, and sell their CO2
associated with fermentation to the beverage industry for carbonation or to food processors for
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flash freezing. Opportunities for CO2 reuse depend on the proximity of ethanol refineries to local
users. The industrial gas supplier Airgas estimates that the ethanol industry captures and recovers
5 to 7 percent of all CO2 that it produces from the ethanol fermentation process (spreadsheet
provided to EPA by Bruce Woerner at Airgas on August 14, 2009, cited in U.S. EPA, 2010b, p.
133). Other sources of GHG emissions, such as those from electricity generation produced from
coal or other GHG-emitting sources, are not currently recovered by the industry.
EISA Section 204 does not include GHG emissions in the set of environmental issues to
be examined in this report. However, EPA did analyze life cycle GHG emissions from increased
renewable fuels use as part of the EISA-mandated revisions to the RFS program. 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. These life cycle performance improvement thresholds are listed in Table 4-2.
Table 4-2. Lifecycle GHG Thresholds Specified in EISA
(percent reduction from 2005 baseline)
Renewable fuela
20%
Advanced biofuel
50%
Biomass-based diesel
50%
Cellulosic biofuel
60%
a - The 20% criterion generally applies to renewable fuel from new
facilities that commenced construction after December 19, 2007.
EPA's methodology for conducting the GHG life cycle assessment included use of
agricultural 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 DOE's GREET model defaults and Intergovernmental Panel on
Climate Change (IPCC) emission factors. The GHGs considered in the analysis were CO2,
methane (CH4), 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 projected that (U.S. EPA, 2010b):
• Ethanol produced from corn starch at a new (or expanded capacity from an
existing) natural gas-fired 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.
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• 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 CCVequivalent emissions by 2022 compared to projected 2022 emissions without
the EISA-mandated changes (see the RFS2 RIA [U.S. EPA, 2010b] for details).
4.3.3 Water Quality and Availability
All biofuel facilities utilize process water to convert biomass to fuel. Water used in the
biorefining process is modest in absolute terms compared to the water applied and consumed in
growing the plants used to produce biofuel. 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., High Plains aquifer, 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 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, since 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. The first step in mitigating water availability
concerns associated with increased biofuel production is to locate production facilities where
water sources are adequate to meet production needs without impacting 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. Biological oxygen
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demand (BOD), brine, ammonia-nitrogen, and phosphorus are primary pollutants of concern
from ethanol facilities, while discharges of BOD, glycerin, and to a certain extent, total
suspended solids (TSS) pose the major water quality concerns from biodiesel facility effluent.
Regulatory controls placed on the quality of biofuel production wastewater discharge can
mitigate water quality impacts. Discharges to publicly owned wastewater treatment works
(POTWs) are subject to general pre-treatment standards in the Clean Water Act (40 CFR 403.5).
Biofuel facilities that discharge their wastewater to POTWs are subject to whatever pre-treatment
limitations are in force 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 onsite 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.
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, 2010b). 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 gallons of water in the production process.
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 et al., 2009); newer facilities tend to consume about 27 percent less water. Wet
mill facilities consume an average of 3.95 gallons of fresh water per gallon of ethanol produced
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(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). New technologies that improve water efficiency will
help mitigate water quantity impacts.
Wastewater effluent from corn starch ethanol facilities is high in BOD (Powers, 2007).
For example, one report found that ethanol production from corn produces wastewater with BOD
from 18,000 to 37,000 mg/L (Pimentel and Pimentel, 2008, p. 380). Ethanol wastewater effluent
can also contain ammonia-nitrogen and phosphorus.
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).
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 onsite 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 price of corn, 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).
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The increase in nitrogen and phosphorus from DDGS in livestock feed has potential
implications for water quality. 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 runoff 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. USDA'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, 2010b); some facilities recycle washwater, which reduces overall
water consumption (U.S. EPA, 2010b). However, water use has been reported as high as three
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, 2010b). New technologies that improve water efficiency will help mitigate water
quantity impacts.
In addition to water use in the washing and evaporation processes, other 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 DOE/USD A 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 gallon 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 wastewaters
with free fatty acids and glycerin (a major co-product of biodiesel production). Despite the
existing commercial market for glycerin, the rapid development of the biodiesel industry has
caused a glut of glycerin production, resulting in many facilities disposing glycerin. Glycerin
disposal may be regulated under several EPA programs, depending on the practice. However,
there have been incidences of glycerin dumping, including an incident in Missouri that resulted
in a large fish kill (U.S. EPA, 2010b).
Other constituents in the biodiesel manufacturing process wastewater 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
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431 to surface or ground water. Typical wastewater from biodiesel facilities has high concentrations
432 of conventional pollutants—BOD, TSS, oil, and grease—and also contains a variety of non-
433 conventional pollutants (U.S. EPA, 2008c).
434 Some biodiesel facilities discharge their wastewater to municipal wastewater treatment
435 systems for treatment and discharge. In some cases, wastewater with sufficiently high glycerin
436 levels has disrupted municipal wastewater treatment plant function (U.S. EPA, 2010b). There
437 have been several cases of municipal wastewater treatment plant upsets due to high BOD
438 loadings from releases of glycerin (U.S. EPA, 2010b). To mitigate wastewater issues, some
439 production systems reclaim glycerin from the wastewater. As another option, closed-loop
440 systems in which water and solvents can be recycled and reused can reduce the quantity of water
441 that must be pretreated before discharge.
442 4.3.4 Impacts from Solid Waste Generation
443 Biofuels may also lead to significant environmental impacts stemming from solid waste
444 generated by various production processes. EPA defines "solid wastes" as any discarded
445 material, such as spent materials, by-products, scrap metals, sludge, etc., except for domestic
446 wastewater, non-point source industrial wastewater, and other excluded substances (U.S. EPA,
447 2010i). A type of solid waste that is of particular interest in the case of biofuel production is the
448 diatomaceous earth that is used as a filter to remove impurities from methyl esters, such as
449 biodiesel. Several reports have indicated that diatomaceous earth may be spontaneously
450 combustible, and disposal sites consider it a potential hazardous waste (Missouri Department of
451 Natural Resources, 2008; Nebraska Department of Environmental Quality, 2009). The high
452 surface area of the diatomaceous earth and the oil sets up a rapid decomposition that creates heat.
453 Further study is needed to investigate this potential hazard and look into mitigation strategies.
454 4.4 Biofuel Distribution
455 The vast majority of biofuel feedstocks and finished biofuel are currently transported by
456 rail, barge, and tank truck. Ethanol and biodiesel are both generally blended at the end of the
457 distribution chain, just before delivery to retail outlets. Storage of biofuels typically occurs in
458 above-ground tanks at blending terminals, in underground storage tanks (USTs), and at retail
459 outlets (as a petroleum-biofuel blend).
460 The primary impacts related to transport and storage of biofuels relate to air quality (i.e.,
461 emissions from transport vehicles and evaporative emissions) and water quality (i.e., leaks and
462 spills).
463 4.4.1 Air Quality
464 4.4.1.1 Ethanol
465 Air pollution emissions associated with distributing fuel come from two sources: 1)
466 evaporative, spillage, and permeation emissions from storage and transfer activities, and 2)
467 emissions from vehicles and pipeline pumps used to transport the fuels (see Figure 4-1).
468 Emissions of ethanol occur both during transport from production facilities to bulk terminals, and
469 after blending at bulk terminals.
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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 CO2, 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, 2010b). In addition, transport and handling of biofuel may result in small but
significant evaporative emissions of VOCs (Hess et al., 2009). 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, 2010b).
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 product
contamination concerns (U.S. EPA, 2010b). 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.,
2009).
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, 2010b).
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 storage tanks are also a major concern. Most states report that underground
storage tanks (USTs) are a major source of ground water contamination (U.S. EPA, 2000).
Preliminary research has shown that any concentration of biofuel in an underground tank also
containing petroleum-based fuels increases the potential for groundwater migration (EPA
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OSWER Biofuels Compendium, http://www.epa.gov/oust/altfuels/bfcompend.htm). A leaking
UST can also present other health and environmental risks, including the potential for fire and
explosion.
EPA's Office of Underground Storage Tanks is working with other agencies to better
understand material compatibility issues associated with older 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 617,000 active USTs, was designed and
tested for use with petroleum fuels, many UST systems currently in use may contain materials
that are incompatible with ethanol blends greater than 10 percent (U.S. EPA, 2009c) or biodiesel.
Although it is not possible to quantify the risk at this time, EPA is developing modeling software
to assess fuels of varying composition on ground water (U.S. EPA, 2010b).
Biodiesel and ethanol blend fuels degrade many non-metallic materials, such as natural
rubber, polyurethane, older adhesives, certain elastomers and polymers used in flex piping,
bushings, gaskets, meters, filters, and materials made of cork. Biodiesel and ethanol blend fuels
also degrade soft metals such as zinc, brass, and aluminum. If a fuel system does contain these
materials and users wish to fuel with blends over B20 (i.e., with fuel containing more than 20
percent biodiesel), replacement with compatible elastomers is needed. In many instances,
especially with older equipment, the exact composition of elastomers cannot be obtained and it is
recommended they be replaced if using blends over B20.
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 by-products.
Further testing and certification of the acceptability of storage tanks and leak detection
systems performance will be crucial to safe storage of biofuels. In addition, developing storage
materials that are resistant to biofuel leaks and spills locating will help prevent spills, and
locating USTs away from ground water supplies, and will mitigate water quality impacts in case
a spill or leak does occur.
Additional details specific to ethanol and biodiesel are discussed below.
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 (85 percent ethanol and 15 percent gasoline) and E10 (10 percent
ethanol and 90 percent gasoline) mixtures at retail. 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 gasoline/ethanol blends. This can cause reduced biodegradation of benzene, toluene, and
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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, 2010b).
There are other potential hazards in addition to those associated with chemical toxicity.
Some spills of gasoline with ethanol 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, 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.
Biodiesel is not water soluble. 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 regular diesel
(Kahn et al., 2007). 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 E10. Nearly half of U.S. gasoline is an
E10 mixture 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 either
conventional gasoline or ethanol blended into gasoline up to 85 percent. Under current market
circumstances, greater deployment of flex-fuel vehicles may be needed to meet the EISA
mandated volume standards. Because of biodiesel's chemical properties, it is not interchangeable
with petroleum-based diesel fuel. For this reason, its blend level is specifically labeled when it is
blended with petroleum diesel (U.S. EPA, 2010b). Biodiesel can 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. There are some concerns regarding maintenance
issues related to engines operated on biodiesel, 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.
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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 211 (v) of the
Clean Air Act 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 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 have 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 (Ginnebaugh et al., 2010; Graham et al., 2008; Yanowitz and McCormick, 2009).
As stated in section 4.3.2, the emission impacts of the 2022 RFS2 volumes in the RFS2
RIA 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 carbon monoxide, benzene, and acrolein in 2022 under the RFS2-mandated
volumes of biofuels, while NOx, 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, 2010b).
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 (Lapuerta et al., 2008; U.S. EPA, 2002). 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).
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). It should be kept in mind 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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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 SOxbiodiesel (U.S. EPA, 2001).
Blending biodiesel in low percentages will not have much impact on sulfur emissions.
With respect to carbon content, plant-based biodiesel is slightly higher than animal-based
biodiesel percentage-wise. 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).
EPA's RFS2 RIA investigated the impacts of 20 volume percent 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 volume percent 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, 2010b).
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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 on countries that
currently rely on imports of agricultural commodities from biofuel producers (Hertel et al., 2010;
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 the environmental impacts outside the
United States caused by U.S. biofuel use. Thus, the following discussion focuses on potential
impacts in foreign countries that may result from implementation of the RFS2 standards.
International trade is the primary mechanism through which foreign nations will be
impacted by U.S. biofuel policy. Ethanol and, to a much smaller degree, biodiesel, have become
global commodities. They are produced in many countries (Figure 5-1) and traded in
international markets. Primary producers of ethanol are Brazil, the U.S., the European Union,
India, and China. Brazil is the only significant exporter of ethanol (Fabiosa, 2010). Changes in
U.S. production and consumption volumes, such as those in RFS2, will result in land allocation
impacts that have global ramifications through international trade and market price. As a crop
price rises, land will be reallocated to grow more of that crop in response to market price;
conversely declining prices for a particular crop will tend to reallocate land away from that less
profitable crop in favor of a more profitable one. Increased competition for arable land is
expected to result in more land being allocated for crop production (Fabiosa, 2010).
z'
Biofuel production
Canada
United States
Colombia
Sweden
Germany
Poland
Denmark
France
China
o
Czech Republic
Slovakia
Austria^ O India
¦-S /
Brazil
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. 0.
Licht world ethanol & biofuels report 2005.
/
C Ethanol
Biodiesel
Thousand mil ion litres
Source: UNEP/GRID-Arendal, 2009.
Figure 5-1: Biofuel Production Map
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Chapter 5: International Considerations
Resulting environmental impacts, both positive and negative, include effects from land
use change and effects 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 U.S. producing around 9 billion gallons (see Table 5-1) (EIA, n.d. [c]). 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
(EIA, n.d. [c]). As a result, 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 (EIA, n.d. [c]).
Table 5-1: Top Fuel Ethanol-Producing Countries from 2005 to 2009
(All figures are in millions of gallons)
C'oiiiKrv/ko^ion
2005
2006
2007
200S
2009
United States
3,904
4,884
6,521
9,283
10,938
Brazil
4,237
4,693
5,959
7,148
6,896
European Union
216
427
477
723
951
China
317
369
440
526
567
Canada
67
67
212
250
287
Jamaica
34
80
74
98
106
Thailand
18
34
46
87
106
India
57
63
69
71
89
Colombia
8
71
72
67
80
Australia
6
20
21
38
54
Other
93
216
276
393
274
Total World
Production
8,957
10,924
14,167
18,684
20,348
Source: EIA, n.d. [c].
The market for the other major biofuel, biodiesel, is concentrated in Europe, which
represented about 60 percent of world production as of 2009 (EIA, n.d. [b]). The other 40 percent
of the market 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 the world total (EIA,
n.d. [b]). 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 (EIA, n.d. [b]). These production
increases have been driven by increased consumption targets. For instance, Brazil has planned to
increase its biodiesel blend from 5 to 10 percent by 2015.
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5.2 Import/Export Volumes
U.S. biofuel import volumes will depend largely on domestic production capacity,
including the efficiency of the domestic ethanol-producing sector, the yields attained, and any
excess demand left to be met via imported biofuel or biofuel feedstocks.
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 comprised 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 U.S. produced in 2009 came from
corn starch; by 2015, this figure is expected to increase to the targeted volume provided for in the
revised Renewable Fuel Standards (RFS2) program (as required under EISA) of 15 billion
gallons (GAO, 2007; U.S. EPA, 2010b). Future production volumes of advanced biofuel that
have not yet been commercially developed are not quite as certain. 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, 2010b). In addition,
U.S. biodiesel production is projected to increase to roughly 1.3 billion gallons by 2019 (FAPRI,
2010d). The RFS2 RIA also projected that the remaining 4 billion gallons needed to meet the
EISA 2022 mandate would be comprised of a combination of imported sugarcane ethanol from
Brazil as well as "other advanced biofuel," including cellulosic biofuel, biomass-based diesel,
and co-processed renewable diesel (U.S. EPA, 2010b). Table 5-2 shows the projected import
volumes forecasted in the RIA for each year from 2011 to 2022.
Table 5-2: RFS2 RIA Projected Imports and Corn Ethanol Production, 2011-2022
2011
2012
2013
2014
2015
201ft
20 r
20IS
2019
2020
2021
2022
l S Cum
Ldianol
Production
12,070
12,830
13,420
14,090
14,790
15,000
15,000
15,000
15,000
15,000
15,000
15,000
Projected Imports
160
180
190
200
390
630
1,070
1,510
1,960
1,880
1,810
2,240
Source: U.S. EPA, 2010b, pp. 77-78.
Figures are in millions of gallons.
As Table 5-2 shows, import volumes will be at or below 200 million gallons 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 rapidly up
until 2015 and then level off, and also because the RFS2 total renewable fuel requirements
increase more rapidly in the later years. 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 (USDA, n.d.) have totaled 17 million gallons -well below
EPA's 200 million gallons forecast (EPA, 2010b). Therefore, ethanol imports may be
significantly lower than the projections in Table 5-2. U.S. biofuel imports and exports will also
be influenced by trade policy, including tariffs and other incentives in the U.S. and in other
countries. Even if the U.S. succeeds in meeting the RFS2 targets, the U.S. likely will continue to
import and export biofuel as individual producers take advantage of international price
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Chapter 5: International Considerations
differences. Over the past decade (2002 to 2009), U.S. ethanol import quantities varied
considerably (see Table 5-3), 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.
Table 5-3: Historical U.S. Domestic Ethanol Production and Imports
2002
2003
2004
2005
200(»
200"7
200S
200')
U.S. Production
2,140
2,804
3,395
3,904
4,884
6,521
9,283
10,938
Imports
13
12
149
136
731
439
530
198
Source: EIA, n.d. [c] for production figures; EIA, n.d. [d] for import figures.
Note: Figures are in millions of gallons.
The bulk of U.S. ethanol imports are sugarcane-based ethanol from Brazil. In 2008, the
U.S. was the largest importer of Brazilian ethanol, followed by the Netherlands and a number of
Caribbean countries (see Table 5-4). However, foreign-produced ethanol is also imported to the
U.S. 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 U.S. to be imported from CBI
member countries duty-free (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, Trinidad and Tobago, (see Table 5-4), is eventually re-exported to the United States.
Looking closer at these Brazilian export figures in Table 5-4, 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 is due to the drop in U.S. imports caused by a
change in energy prices, as well 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
Table 5-4: 2008-2009 Brazilian Ethanol Exports by Country of Destination
Volume (million pillions)
Dosliiiiilioii ( onillr\
200S
V'ii of l oCil
200')
V ii ol° 1 (Hill
Total
1,352.9
100%
870.8
100%
United States
401.6
29.7%
71.9
8.3%
Netherlands
351.9
26.0%
179.2
20.6%
Jamaica
115.3
8.5%
115.6
13.3%
El Salvador
94.1
7.0%
18.8
2.2%
Japan
69.6
5.1%
74.0
8.4%
Trinidad and Tobago
59.3
4.4%
37.0
4.2%
Virgin Islands (U.S)
49.7
3.7%
3.4
0.4%
Korea, Republic of (South Korea)
49.3
3.6%
82.9
9.5%
Costa Rica
28.9
2.1%
26.5
3.0%
Nigeria
25.9
1.9%
30.6
3.5%
United Kingdom
18.4
1.4%
42.7
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.
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Chapter 5: International Considerations
well as the recent strengthening of Brazil's currency, could significantly hinder Brazil's ability to
supply the U.S. market moving forward. Even if the 54-cent-per-gallon tariff on ethanol imports
does expire as planned at the end of 2010, these factors may limit future imports (USDA,
2010d).
The U.S. 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 5-2) 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.
2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09
Harvest Year
~ Other
SUAE
m India
0 Austrailia
BEU
¦ Mexico
H Canada
Source: ERS, 2010a.
Note: Original data were converted from liters to gallons, graph was created by ERG.
Figure 5-2: Historic U.S. Ethanol Export Volumes and Destinations
Table 5-5 shows the 2008 U.S. biodiesel trade balance. At that time, 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 in 2008
(EIA, n.d.[b]). 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, 2010d).
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Table 5-5: 2008 U.S. Biodiesel Balance of Trade
llem
Quantify
U.S. Production
774 million gallons
U.S. Consumption
412 million gallons
Production - consumption =
362 million gallons
U.S. Imports
315 million gallons
U.S. Exports
677 million gallons
Exports - Imports =
362 million gallons
Source: EIA, 2009, n.d.[c].
5.3 Environmental Impacts of Direct and Indirect Land Use Changes
The issue of land use change inherently includes international considerations, as the
demand for biofuel in the U.S. 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. In this report, land use is defined as "the human
use of land involving the management and modification of natural environment or wilderness
into built environment such as fields, pastures, and settlements". Land use changes are
considered either direct or indirect. In the context of biofuels, direct land use change (DLUC)
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 sugarcane on Brazilian land, which was previously
native forest or used for another non-biofuel crop, for the purpose of increasing the supply of
ethanol to export to the United States. Indirect land use change (ILUC) 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 reduced U.S. corn exports caused by
increased U.S. corn ethanol production. 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. However, 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.
In its RFS2 Regulatory Impact Analysis, EPA estimated greenhouse gas (GHG) impacts
of direct and indirect land use change using the FAPRI-CARD model.24 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: change in U.S.
exports and changes in domestic U.S. prices (U.S. EPA, 2010b). Using this model, along with
MODIS satellite data and other models, the 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 5-3, 5-4, 5-5, and
24 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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5-6 and in Table 5-6. In Figures 5-3, 5-4, 5-5, and 5-6, each column shows the marginal impact
of a scenario that focuses on that particular feedstock in isolation.
The model forecasts that, by 2022, for every increase of 1,000 gallons of corn starch
ethanol production in the U.S., 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 5-3) (U.S. EPA, 2010b). Thus, as the U.S.
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 may 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 will 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., 2010; 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 U.S. is expected to
reach by 2015 or sooner (GAO, 2007; U.S. EPA, 2010b), indirect land use change impacts
resulting from changing trade patterns of corn and other grains may level off at that point. In
fact, U.S. biofuel consumption could decrease pressure on conversion of land to agricultural use
if agricultural yield improvements occur or if cellulosic technologies develop to replace
conventional ethanol production.
a> Wheat
'/. Sorghum
¦ Rice
¦ Cotton
Barley
¦ DG
¦ Soybean Meal
¦ Soybean Oil
¦ Soybeans
¦ Corn
Corn Ethanol
Switchgrass Bhanol Imported Bhanol
Source: U.S. EPA, 2010b.
Figure 5-3: Change in U.S. Exports by Crop Anticipated to Result from EISA
Requirements by 2022 (tons per 1,000 gallons of renewable fuel)
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The model also predicts that the additional biofuel produced to meet the EISA mandates
compared to "business as usual" (2.7 billion gallons of corn starch ethanol, 7.9 billion gallons of
switchgrass cellulosic ethanol, 1.6 billion gallons of imported sugarcane ethanol, and 0.5 billion
gallons of soybean biodiesel) will lead to the creation of 2 million acres, 3.4 million acres, 1.1
million acres, and 1.7 million acres, respectively, of additional international cropland (see Table
5-6) to supply U.S. biofuel imports and also to make up for the U.S. reductions in exports shown
in Figure 5-3 (U.S. EPA, 2010b).
Table 5-6: Changes in International Crop Area Harvested by Renewable Fuel Anticipated
to Result from EISA Requirements by 2022
Feedstock's Marginal Effect
Considered
International Crop Area Change
(000s acres)
Normalized Crop Area Change
(acre / billion BTU)
Corn Ethanol
1,950
9.74
Soy-Based Biodiesel
1,675
26.32
Sugarcane Ethanol
1,063
10.82
Switchgrass Ethanol
3,356
5.56
Source: U.S. EPA, 2010b.
Note: Figures converted from hectare to acre
Further, these direct and indirect land use changes will lead to significant GHG emissions
according to the model (before accounting for GHG savings resulting from petroleum displaced
as the biofuel is consumed). Figure 5-4 shows that, based on the model presented in the RIA,
soy-based biodiesel causes the largest release of international land use change GHG
emissions. The majority of international land use change emissions originate in Brazil in the corn
ethanol and switchgrass ethanol scenarios. This is largely a consequence of projected pasture
expansion in Brazil, and especially in the Amazon region where land clearing causes substantial
14
L
I Soy Biodiesel
I Com Ethanol
Sugarcane Ethanol
I Switchgrass Ethanol
Brazil
Source: U.S. EPA, 2010b.
Rest of World
World
Figure 5-4: International Land Use Change GHG Emissions by Renewable Fuel
Anticipated to Result from EISA Requirements by 2022 (kgC02e/mmBTU)
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GHG emissions. Of the renewable fuels analyzed, the model found that sugarcane ethanol causes
the least amount of land use change emissions. This was 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.
The GHG emissions shown above can be seen as an international "carbon debt"
(Fargione et al., 2008). Clearing forested areas or pasture land for new cropland creates this
carbon debt in which microbial decomposition of organic carbon stored in plant biomass (e.g.
branches, leaves, and fine roots) and soils leads to a prolonged period of GHG emissions. As
described in the 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,
2010b). The conversion of higher carbon-storing types of land such as tropical rainforest will
lead to more carbon emissions (U.S. EPA, 2010b). A 2008 study forecasted that land conversion
of natural ecosystems to cropland would release an estimated 17 to 420 times as much carbon
dioxide as the biofuels themselves can reduce per year by displacing petroleum fuel (Fargione et
al., 2008). Therefore, biofuel consumption may take many years to "pay down" the carbon debt
created from production through the GHG savings from 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 5-5 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 cropland will emerge in foreign countries if land use change does occur. This
is an important source of uncertainty as GHG and other environmental impacts could vary
significantly depending on what crops are grown to offset decreasing U.S. agricultural exports.
8 -
2 -
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, 2010b.
I Soy Biodiesel
¦ Corn Ethanol
Sugarcane Ethanol
I Switchgrass
Ethanol
Figure 5-5: Harvested Crop Area Changes by Region Anticipated to Result from EISA
Requirements by 2022, 2022 (ha / billion BTU)
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Because Brazil will likely be a major supplier of U.S. ethanol, it is informative to
consider land use changes there. Brazil faces challenges of multiple forms of land use change,
both direct and indirect. Land use changes would occur as Brazil increases ethanol production by
converting more land previously used to grow other agricultural goods or pasture lands to grow
sugarcane. As pasture lands are converted to sugarcane production, ranchers are pressured to
"intensify" livestock on smaller portions of land or clear more land (possibly Amazon rainforest
or Cerrado woodland) (Bustamante et al., 2009). Figures 5-4 and 5-6 isolate the impacts on
Brazil alone. The data presented in Figure 5-6 appear consistent with the prediction that pasture
land will decrease in Brazil, while increasing in the rest of the world. However, it is unclear if
this will result in rainforest loss or simply mean a greater number of livestock per acre. There are
differing opinions on the result of this tradeoff 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). A recent study (Fabiosa et al., 2010) suggests that sugarcane-
based ethanol production in Brazil has less significant impact on existing arable land allocation
than corn-based ethanol expansion in the United States. Fabiosa also notes that increasing corn
starch-based ethanol to 15 billion gallons in the U.S. would increase corn crop area in the United
States by nearly 13 percent (corn crop area in Argentina and Brazil would increase by 9.5 and
4.5 percent, respectively).
2
0
-2
¦ Corn Ethanol
¦ Soy Biodiesel
-4
¦ Sugarcane Ethanol
¦ Switchgrass Ethanol
-6
-8
-10
Amazon Central- Northeast North- South Southeast Brazil
Biome West Coast Northeast
Cerrados Cerrados
Source: U.S. EPA, 2010b.
Figure 5-6: Pasture Area Changes in Brazil by Renewable Fuel Anticipated to Result from
EISA Requirements by 2022 (ha / billion BTU)
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. It has been
suggested that, because biofuel production requires approximately 70 to 400 times as much water
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Chapter 5: International Considerations
as other energy sources such as fossil fuels, wind, and solar, an increase in biofuel crop
production could further strain global supplies of water (Gerbens-Leenes et al., 2008). 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 agricultural use from feedstock production
expands. Conversion of land to feedstock production will 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 by-product 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 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. Examples of this have already been seen around
the world. For instance, in Southeast Asia, tropical peat swamps have been degraded because of
loss of forest cover due to logging for timber and conversion of forests to oil-palm plantations for
biofuel (Wosten et al., 2006). However, biofuel production was not the only cause of land
conversion, and it is possible that food-related demands for palm oil would have caused similar
deforestation.
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. This method 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, 2010b). Like many of the effects discussed
so far, the severity of air emissions will be highly sensitive to the feedstock chosen, location of
production, and management practices.
Finally, if increased biofuel consumption in the U.S. 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
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Chapter 5: International Considerations
example, Indonesia (palm oil), Malaysia (palm oil), and Brazil (sugar ethanol) all contain
ecosystems with well above average biodiversity. Depending where biofuel feedstock production
occurs, and the manner in which it occurs, impacts to biodiversity could be significant.
5.5 Concluding Remarks
Projections indicate that the EISA biofuel targets will likely alter U.S. and international
trade patterns. How countries respond to U.S. market conditions could affect net GHG savings
derived from biofuel consumption and the environmental impacts that result from biofuel
production. As with biofuel production in the U.S., these impacts will depend largely on where
the crops are grown and what agricultural practices are used to grow them. To the extent that
local environmental impacts will have broader implications, such as contributing to global
warming, global mitigation strategies will have to consider the international implications of
biofuel production. Decisions made about what feedstocks to use, where to produce them, and
what production methods to employ will have significant environmental and economic
implications.
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Chapter 6: Conclusions and Recommendations
6. Conclusions and Recommendations
6.1 Conclusions
A variety of factors make it difficult to draw conclusions about the potential
environmental and resource conservation impacts of the increased biofuel production and use
mandated by the Energy Independence and Security Act. Of the six feedstocks discussed in this
Report, only corn starch and soybean have been implemented at commercial scale to produce
ethanol and biodiesel, respectively. Production of biofuel from the other four feedstocks
discussed in this report is in various stages of research and development. Even for corn starch
and soybean, data needed to perform a thorough environmental life cycle assessment are
incomplete and the relevant available data often have a high degree of uncertainty. Nevertheless,
initial conclusions can be drawn about how increased biofuel production and use likely will
affect (or is affecting, in the case of corn starch and soybean) water quality and quantity, soil and
air quality, and ecosystems (biodiversity and invasive species) based on the data available as of
July 2010. These conclusions are presented below for the full greenhouse gas (GHG biofuel life
cycle (Section 6.1.1) and for stages in the life cycle: feedstock production (Section 6.1.2); biofuel
production, transport, and storage (Section 6.1.3); and biofuel end use (Section 6.1.4). (See
Figure 2-3 in Chapter 2 for life cycle description.) These conclusions do not account for existing
or potential future mitigation measures or regulations.
6.1.1 Emissions Reduction
Fuel combustion at ethanol and biodiesel facilities releases GHGs. However, when the
entire biofuel life cycle is considered (as described in Chapter 4, Section 4.3.2.3), the revisions to
the Renewable Fuel Standard (RFS2) program mandated by the Energy Independence and
Security Act (EISA) are expected to achieve a 138-million metric ton reduction in CO2-
equivalent emissions by 2022.
6.1.2 Feedstock Production
6.1.2.1 Overview
Figure 6-1 provides a qualitative overview, based on EPA's best professional judgment,
of the maximum potential range of domestic environmental and resource conservation impacts
associated with per unit area production of the six feedstocks discussed in this Report.
Qualitative assessment is grounded in information and data published in the peer-reviewed
literature through July 2010, which are described in Chapter 3. Range extremes for each impact
category were determined by considering plausible conditions under which a "most negative"
and "most positive" environmental impact would likely arise. Key assumptions for these
conditions appear in Figure 6-1; for full, detailed elaboration of the conditions, which encompass
a variety of factors, including land use, feedstock production management choices, region,
technology used, regulatory control, and mitigation measures, see Appendix C, Table C-l.
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Chapter 6: Conclusions and Recommendations
Impact Category
^Rej3ortSection^_
Maximum Potential
Range of Environmental
Impacts per Unit Area1
Key Assumptions
Maximum Potential i Maximum Potential
Negative Environmental [ Positive Environmental
Impact I Impact
Water Quality (3.2.2)
Water Quantity (3.2.3)
Soil Quality (3.2.4)
Air Quality (3.2.5)
Biodiversity (3.2.6.1)
Invasiveness (3.2.6.2)
Production of non-irr. corn
Conventionallymanagedcorn ¦ Dive rsi on of ex isti ng corn prod u ctio n
replaces CRP J to fuel
Irrigated (irr.) corn replaces non-irr.
land
Conventionallymanagedcorn jDiversionofexistingcornproduction
replaces CRP 1 to fuel
Irrigated corn replaces non-irrigated 1 Diversion of existing corn production
land ¦ to fuel
Conventionallymanagedcorn 1 Dive rsi on of ex isti ng corn prod u ctio n
replaces CRP J to fuel
Negligible known impact
Water Quality (3.2.2)
Water Quantity (3.2.3)
Soil Quality (3.2.4)
Air Quality (3.2.5)
Biodiversity (3.2.6.1)
Invasiveness (3.2.6.2)
Soy replaces CRP
Irr. soy replaces non-irr. land
Soy replaces CRP
Irr. soy replaces non-irr. land
Soy replaces CRP
Soy replaces corn
Non-irr. soy replaces irr. corn
Soy replaces corn
Non-irr. soy replaces irr. corn
Soy replaces corn
Negligible known impact
Water Quality (3.2.2)
Water Quantity (3.2.3)
Soil Quality (3.2.4)
Air Quality (3.2.5)
Biodiversity (3.2.6.1)
Invasiveness (3.2.6.2)
1=31
m
1=9
High removal on erodible land
High removal on irr. land
High removal on erodible land
Extra harvesting pass required
High removal on erodible land
Site-specific removal to minimize
erosion
Site-specific removal to minimize
need for irrigation
Site-specific removal to minimize
erosion
Single-pass harvest with grain
Site-specific removal to minimize
erosion
Negligible known impact
Water Quality (3.4.2)
Water Quantity (3.4.3)
Soil Quality (3.4.4)
Air Quality (3.4.5)
Biodiversity (3.4.6.1)
Invasiveness (3.4.6.2)
Short interval woody crop replaces 1
mature plantation J
SRWC that is irrigated 1
Short interval woody crop replaces 1
mature plantation 1
See "Water Quality" + woody crop J
emits isoprene ,
Short interval woody crop replaces (
mature plantation 1
Woody crop (ex. Eucaluptus) 1
invades [
Long interval woody crop replaces
short interval plantation
Thinning or non-irr. woody crop
Long interval woody crop replaces
short interval plantation
See "Water Quality" + woody crop
with low isoprene emissions
Long interval woody crop replaces
short interval plantation
Non-invasive woody crop used
Water Quality (3.3.2)
Water Quantity (3.3.3)
Soil Quality (3.3.4)
Air Quality (3.3.5)
Biodiversity (3.3.6.1)
Invasiveness (3.3.6.2)
Conventionally managed grass r
replaces CRP J
Irr. grass replaces non-irr. land use 1
Conventionallymanagedg rass 1
replaces CRP 1
Irr. grass replaces non-irr. land use |
Uniformly managed grass replaces 1
CRP [
N on - nativ e g rasses invade 1
Conservation managed grass
replaces conventional corn
Non-irr. grass replaces irr. corn
Conservation managed grass
replaces conventional corn
Conservation managed, non-irr.
grass replaces irr. corn
Diversely managed grass replaces
conventional corn
Non-invasive grasses used
Water Quality (3.5.2)
Water Quantity (3.5.3)
Soil Quality (3.5.4)
Air Quality (3.5.5)
Biodiversity (3.5.6.1)
Invasiveness (3.5.6.2)
Untreated effluent is discharged
Grown with wastewater
Ci
l=Z>
, .1 Recycled wastewater, closed
Freshwater, open pond in dry region.
K K 1 bioreactor
Negligible known impact
Manufactured nutrients added 1 Wastewater nutrients used
Negligible known impact
Non-invasive algae in closed
Algae in open ponds invade
bioreactors
Bars are conditioned on key assumptions described briefly here and fully elaborated in Appendix C, Table C-1.
Legend
Maanitude
Tvce of Effects
Certainty
(length of bar)
Negative effects
Negligible effect
Positive effects (shading)
Relatively large
I 1
O
1 1 Least certain
Moderate
l—i
O
1 | MnriP.ratP.ly rp-t+ain
Relatively minor
•
Most certain
Figure 6-1: Maximum Potential Range of Environmental Impacts (on a Per Unit Area
Basis) Resulting from Cultivation and Harvesting of the Six Biofuel Feedstocks
Considered in This Report
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Impacts shown in this figure are only relative to each other. No attempt has been made to
compare impacts to those of petroleum production, nor do impacts represent possible
environmental benefits gained by petroleum displacement. In addition, impacts are only relevant
for those regions where each feedstock is likely to be grown (see Chapter 3). Impacts for corn
stover do not include the impacts of corn production itself but rather impacts of stover removal
above and beyond corn cultivation and harvest. Air quality impacts do not include changes in
GHG emissions.
Bar direction signifies whether the effect is negative (left) or positive (right). Bar length
indicates the anticipated magnitude of effect, and shading density depicts the associated degree
of certainty. A circle signifies that no net effect is anticipated. Section numbers next to the
impact category indicate where in this Report the information that provides the basis for the bars
in this figure can be found.
When the potential range of production conditions is considered, four feedstocks
(soybean, woody biomass, perennial grasses, and algae) are anticipated to have both negative and
positive environmental impacts. The most positive environmental outcome for corn starch and
corn stover is no net effect, achieved largely through minimization of land use change and
through site-specific agricultural management, including comprehensive conservation practices.
Most feedstocks (corn starch, soybean, corn stover, woody biomass, and perennial grasses) have
the potential to have impacts in at least five of the six environmental categories shown in the
figure; algae are anticipated to have impacts in only four of the categories (water quality, water
quantity, air quality and invasiveness). A higher degree of certainty is associated with the two
feedstocks that are already commercially produced (corn starch and soybean) than with those in
development (corn stover, woody biomass, perennial grasses, and algae).
6.1.2.2 Conclusions
Key conclusions concerning environmental impacts of biofuel feedstock cultivation are
as follows:
Water Quality. Increased cultivation of feedstocks for biofuel may affect water quality
and hypoxia conditions in the Gulf of Mexico and other vulnerable water bodies through
increased erosion and runoff and leaching of fertilizers and pesticides to ground and surface
waters. Cellulosic feedstocks may have less water quality impact than corn starch and corn
stover due to projected decreased fertilizer use and decreased soil erosion. Comprehensive
management systems and practices are one tool that may mitigate some of these impacts if they
are widely and effectively implemented. Compared to corn and soybeans, cultivation of some
cellulosic feedstocks may provide benefits, including soil stabilization, reduced soil erosion and
nutrient runoff, and increased nutrient filtration.
Water Quantity. Effects of feedstock production on water availability vary greatly by
feedstock, processes used to produce the feedstock, and location. Corn and soybean cultivation
for biofuel production have a greater water demand than perennial grasses, woody biomass, and
algae. Regional differences are mostly due to precipitation which, when insufficient, necessitates
supplemental irrigation, which can be a significant water use in the biofuel production process.
In irrigated regions, the method and efficiency of irrigation can also affect the amount of water
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used. For both corn and soybeans, the source for irrigation water varies from region to region,
potentially affecting water tables and/or surface waters. Removal of corn stover can reduce soil
moisture, resulting in a need for increased irrigation. Water quantity effects may be mitigated by
growing feedstocks in areas that do not require irrigation and by using efficient irrigation
practices, such as reclaimed water use.
Soil Quality. Increased cultivation of corn, soybean, woody biomass, and perennial
grasses will affect soil quality in various ways, depending on the feedstock. Effects include
increased soil erosion, decreased soil organic matter content, increased soil GHG emissions, and
increased nitrogen and phosphorus losses to ground and surface waters. Annual crops, such as
soybean and corn, will have higher erosion rates than non-row crops, such as perennial grasses
and woody biomass. However, cultivation of corn or soybean at higher rates (i.e., greater yield
per acre) on existing corn or soybean acreage likely will not alter soil erosion rates significantly.
Soil quality impacts from biofuel feedstocks may be ameliorated by the choice of feedstock and
by the diligent use of generally accepted conservation practices.
Air Quality. Activities associated with growing biofuel feedstocks emit air pollutants,
which affect air quality, with effects varying by region. Production of row crops will affect air
quality more than non-row crops. Pollutants from row crops include farm equipment emissions
and soil and related dust particles (e.g., fertilizer, pesticide, and manure) made airborne as a
result of field tillage and fertilizer application, especially in drier areas of the country.
Biodiversity. Increased cultivation of corn and soy feedstocks could significantly affect
biodiversity (1) through habitat alteration when uncultivated land is moved into production, and
(2) from exposure of flora and fauna to high pesticides concentrations. Aquatic habitat may be
impaired by soil erosion and nutrient runoff. Biodiversity impacts can be mitigated by choosing
crop and cultivation methods that minimize habitat alteration and runoff.
Invasiveness. Corn and soybean pose little risk of becoming weedy or invasive in the
U.S. In certain regions, some perennial grasses, short-rotation woody crops, and algae strains
pose greater, though uncertain, risk of becoming an agricultural weed or invasive in natural
areas. Transport of grass and short-rotation woody crop seeds and plant parts capable of
vegetative reproduction from the field to biofuel production facilities may increase the
opportunity for seeds and plant parts capable of vegetative reproduction to establish themselves
in feral populations along transportation corridors. Algae produced in photo-bioreactors are less
likely to become invasive than algae produced in open ponds.
6.1.3 Biofuel Production, Transport, and Storage
As described below, biofuel production, transport, and storage can impact water quality,
water quantity, and air quality.
6.1.3.1 Overview
Figure 6-2 provides a qualitative overview, based on EPA's best professional judgment,
of the maximum potential range of domestic environmental and resource conservation impacts
associated with per unit volume production, transport, and storage of ethanol from corn and
cellulosic feedstocks and biodiesel from soybean (though biodiesel from algae should not be
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appreciably different). Qualitative assessment is grounded in information and data published in
the peer-reviewed literature through July 2010, which are described in Chapter 4. As with Figure
6-1, range extremes for each impact category were determined by considering plausible
conditions under which a "most negative" and "most positive" environmental impact would
likely arise. Key assumptions for these conditions appear in Figure 6-2; for full, detailed
elaboration of the conditions, which encompass a variety of factors, including region, technology
used, regulatory control, and mitigation measures, see Appendix C, Table C-2.
Impacts shown in this figure are only relative to each other. No attempt has been made to
compare impacts to those of petroleum production, nor do impacts represent possible
environmental benefits gained by petroleum displacement.
Bar conventions used in Figure 6-1 are the same as those used in Figure 6-2.
As Figure 6-2 illustrates, the environmental impacts of biofuel production, transport, and
storage are expected to be largely negative (see Chapter 4 for more details). However, for all
three fuel types, impacts can be minimized through appropriate facility siting, waste treatment,
and improved, more efficient technology.
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.
Water Quantity. Biofuel production facilities draw on local water supplies to produce
fuel, but the quantity of water used is modest compared to that required to produce biofuel
feedstocks. Impacts will depend on the location of the facility in relation to water resources.
Water availability issues can be mitigated by siting production facilities where water is abundant.
Air Quality. Emissions from biofuel production facilities are generated primarily by the
stationary combustion equipment used for energy production. Compared to two scenarios ([1]
the original renewable fuel standard of 7.5 billion gallons, and [2] a 2022 renewable fuel volume
of 13.6 billion gallons projected by the Department of Energy's 2007Annual Energy Outlook),
RFS2-mandated increased biofuel production will likely result in decreased emissions of carbon
monoxide and benzene, and increased emissions of nitrogen oxides, volatile organic compounds,
particulate matter, and several air toxics. Since 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 process and energy generation equipment.
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Chapter 6: Conclusions and Recommendations
Impact Category
(Report section)
Maximum Potential
Range of Environmental
Impacts per Unit
Volume1'2
Key Assumptions
Maximum Potential
Negative Environmental
Impact
Maximum Potential
Positive Environmental
Impact
Corn
Ethanol
Water Quality
(4.4.2, 4.6.2)
Water Quantity
(4.3.3)
Air Quality3
(4.3.2, 4.4.1, 4.5.1, 4.6.1)
i
High BOD effluent; DDG byproduct | Eff|uen( treated; DDG_fed
fed to livestock with poor waste ¦ , .
, , . livestock waste managed;
management; underground storage1 , 3
tanks (USTs) leak | USTs do not leak
1
1
3-6 gallons water/gallon 1 . . .
... i Improved water use efficiency
ethanol .
i
i
i
.. aaa~ , , . Ethanol facility natural gas-
Ethanol facility coal-powered 1 ,
i powered
i
N
Soybean
Biodiesel
Water Quality
(4.4.2, 4.6.2)
Water Quantity
(4.3.3)
Air Quality3
(4.3.2, 4.4.1, 4.5.1, 4.6.1)
i
i
i
High BOD, total suspended i .
r i , ¦ i*. Effluent treated
solids (TSS), glycerin effluent 1
i
i
i
i
<1 gallon water/gallon 1 <1 gallon water/gallon
biodiesel biodiesel
i
i
i
f • §¦. , Biodiesel facility natural gas-
Biodiesel facility coal-powered 1 .
i powered
i
<
N
Cellulosic
Ethanol
Water Quality
(4.4.2, 4.6.2)
Water Quantity
(4.3.3)
Air Quality3
(4.3.2, 4.4.1, 4.5.1, 4.6.1)
l=
i
i
¦ I- i . ii^t , , i Effluent treated; USTs do not
High BOD effluent; USTs leak ,
i leak
i
i
i
i
10 gallons of water/gallon > . . .
„ . . . i Improved water use efficiency
cellulosic ethanol
i
i
i
i
ir aa,, , , 1 Ethanol facility natural gas-
Ethanol facility coal-powered ¦ ,
i powered
i
N
1 Bars are conditioned on key assumptions described briefly here and fully elaborated in Appendix C, Table C-2.
Comparisons are made on the basis of equal volumes of the biofuels indicated.
3lmpacts shown are immediate impacts from biofuel production to end use. No attempt is made in this table
259 to represent air quality impacts based on displaced gasoline emissions. See Section 4.5 for more information.
160
Legend
Maanitude
Tvoe of Effects
Certainty
(length of bar)
Negative effects
Negligible effect
Positive effects (shading)
Relatively large
1 1
O
1 1 Least certain
Moderate
1=1
O
1 | Moderately certain
Relatively minor
*
•
Most certain
162 Figure 6-2: Maximum Potential Range of Environmental Impacts (on a Per Unit Volume
163 Basis) Resulting from Ethanol and Biodiesel Production, Transport, and Storage
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6.1.3.2 Biofuel Transport and Storage
Biofuel transport and storage may impact water and air quality.
Water Quality. Leaks and spills of biofuel from above-ground, underground, and
transport tanks can potentially contaminate ground, surface, and drinking water. A leaking
underground storage 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 will also prevent biofuel leaks.
Air Quality. 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.
6.1.4 Biofuel End Use
Air Quality. 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. Emissions in 2022 are expected to be higher for some pollutants and
lower for others compared to two scenarios (described in 6.1.3.1). In general, biodiesel
combustion has been shown to decrease particulate matter, carbon monoxide, and hydrocarbon
emissions, increase nitrogen oxide emissions, and increase ozone-forming potential compared to
fossil fuel diesel. Emissions from ethanol use are independent of feedstock; in contrast,
emissions from biodiesel use differ according to the feedstock. Particulate matter, nitrous oxide,
and carbon monoxide emissions are higher for plant-based biodiesel than for animal-based
biodiesel.
6.1.5 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 will
likely occur across the globe as the U.S. 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, Indonesia (palm oil),
Malaysia (palm oil), and Brazil (sugar ethanol) all contain ecosystems with well-above-average
biodiversity. Depending where biofuel feedstock production occurs, impacts to biodiversity
could be significant. Particularly in Malaysia and Indonesia, which have already lost
considerable forest cover due to their large timber industries, expansion of palm oil plantations
for biodiesel could potentially compound impacts on natural resources. However, because corn
ethanol, the biofuel with the greatest potential for international impact in terms of trade pattern
changes, is limited by the RFS2 and is likely to reach this limit in the next few years, these
international impacts could level off as corn starch ethanol production levels off or is replaced by
more advanced technologies.
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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
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.
6.2 Recommendations
EISA Section 204 specifies that EPA 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. Impacts from corn starch and soybean
production are relatively well understood, however, 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.
6.2.1 Comprehensive Environmental Assessment
The biofuel industry is poised for significant expansion in the next few years. A variety
of new technologies likely will be implemented and old technologies modified to meet the
demands of affordable and sustainable petroleum fuel alternatives. 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. However, as
noted earlier, the inherent complexity and uncertainty of environmental impacts across the
biofuel supply chain make it difficult to provide assessments that are sufficiently definitive to
inform environmental decisions.
Recommendation: Develop and evaluate environmental life cycle assessments for
biofuels. With this Report, EPA and the U.S. Departments of Agriculture and Energy (USDA
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 by-products and provide a comparative
context to fossil fuels. As described in Chapter 7, future assessments will be comprehensive and
will 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.
6.2.2 Coordinated Research
The biofuel industry is expected to expand rapidly and broadly. This expansion will be
shaped to a large degree by the research behind the technological developments that make
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Chapter 6: Conclusions and Recommendations
biofuel production feasible. It will be 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 biofuel
research cooperation. 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.
6.2.3 Mitigation of Impacts from Feedstock Production
As the biofuel industry expands, it will be important to optimize benefits while
minimizing adverse impacts. Since 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 and implement best management and conservation
practices and policies that will avoid or mitigate negative environmental effects from
biofuel production and use. 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 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.
6.2.4 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 U.S. 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 may result in indirect land use change in
the form of land conversion to agriculture in other countries. Additional biofuel produced to
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meet the EISA mandates will potentially lead to increases in acreages of international cropland,
although these increases may level off after 2015 (see Section 5.2).
Recommendation: Engage the international community in cooperative efforts to
identify and implement sustainable biofuel practices that minimize environmental impact.
U.S. and international capacity to minimize the consequences of land use change will depend not
only 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. The U.S. 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 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 will use for its future assessments, beginning with
the 2013 Report to Congress. In developing future assessments, EPA will work closely with the
U.S. Departments of Agriculture and Energy (USD A and DOE) 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, 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,
2010b) 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 2013 Assessment
This section briefly describes key components that EPA plans to utilize in conducting its
2013 assessment. Comprehensive environmental assessment (CEA) would provide an organizing
framework for evaluating and, where possible quantifying, risk and benefits of biofuel
production and use. CEA would integrate LCA, described in Section 7.2.1, and environmental
risk assessment, described in Section 7.2.2. The latter could be used to systematically assess
environmental risks, both human health (see Section 7.2.3) and ecological, for each stage in the
life cycle and potentially cumulative impacts. Conceptual models (Section 7.2.4) 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 (Section
7.2.5) 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
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
42 practices in ameliorating these impacts. A scenario-based approach (Section 7.2.6) is currently
43 envisioned to provide a comparative basis for projecting and assessing how biofuel production
44 and use will affect the environment in future years. Finally, the 2013 assessment will include
45 other components, such as a comparison to fossil fuels, net energy balance, and analysis of
46 market impacts (Section 7.2.7), that are important to evaluating biofuel impacts.
47 7.2.1 Life Cycle Assessments
48 LCAs have been widely used to assess the potential and pitfalls for bio-ethanol as a
49 transportation fuel (von Blottnitz and Curran, 2007). The majority of such analyses have focused
50 on particular components such as GHG emissions and energy balances (Hill, 2009), with varied
51 results based on the assumptions and input parameters used to drive assessments. In some cases,
52 the scientific community seems close to reconciling the various assumptions used by different
53 investigators (Anex and Lifset, 2009). To better address the EISA reporting mandate, however, a
54 broader profile of potential environmental impacts should be considered. This approach has been
55 used in several studies (von Blottnitz and Curran, 2007) and applied to evaluating trade-offs for
56 fuel options (Davis and Thomas, 2006). As part of the 2013 assessment, EPA anticipates
57 utilizing LCA in a broad context, one that considers a full range of potential environmental
58 effects and their magnitude. A variety of environmental LCA approaches have been developed
59 that would prove useful for such an effort (Duncan et al., 2008; Ekvall, 2005; Hill et al., 2006;
60 Puppan, 2002).
61 7.2.2 Environmental Risk Assessment
62 Environmental risk assessment will be fundamental for systematically evaluating the
63 human and environmental impacts of the activities involved in biofuel production and use.
64 Environmental risk assessment can be used to estimate the risks associated with each stage of the
65 biofuel life cycle, from production of raw materials through transportation to waste products.
66 Environmental risk assessment is initiated by clearly articulating the problem (i.e., problem
67 formulation), describing the critical factor, pathways, and linkages among these factors,
68 quantifying human/ecological exposure and effects, and subsequently characterizing and
69 estimating the risks associated these effects. Environmental risk assessment will identify which
70 stages in the biofuel life cycle contribute the greatest risk so that more informed risk
71 management practices can be developed and implemented for these stages.
72 7.2.3 Human Health Assessment
73 Increasing biofuel use presents the potential for distinct health effects separate from the
74 known impacts of fossil fuels. The fate and transport of these new fuel blends in the environment
75 and the subsequent exposures and human health effects have not been fully studied. Drawing
76 definitive conclusions on health impacts is not realistic at this time, given the unknowns
77 surrounding the feedstocks, technologies, and fuel blends that will be used to meet target
78 volumes, and the relatively limited availability of toxicological data to directly evaluate the
79 potential health effects of the various emissions.
80 Health effects will be assessed in the 2013 report, provided adequate data are available.
81 In examining the health risks and benefits of increased biofuel use, it will be important to
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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 2010 assessment lay 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 D provides detailed conceptual diagrams for each
of the feedstocks and fuels considered in this Report. Based on the information gathered during
this 2010 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 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
impacts, and how effective regulatory and voluntary management practices, risk management
practices, and other measures are in protecting the environment. While current environmental
monitoring by various agencies can provide helpful information, targeted monitoring for
potential biofuel impacts will be needed, requiring a collaborative effort across multiple agencies
and other organizations. Indicators and measures will be important for a variety of environmental
effects, including GHG emissions, human and ecological health indicators, eutrophication, and
many others. These metrics will inform decisions at all levels along the biofuel supply chain and
well beyond the scope of the individual decision.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
ethanol/bio dies el
demand
LEGEND
activity
product
land
portion yield
to biofuel
crop
rotation
yield improvement
environmental
impact
feedstock
fe e dsto ck pro duction
pesticide use
fertiliser use
fuel&
energy use
water use
A land cover
A invasive
species
A soil quality
A air quality
A water quality
[A water availability;
A ecosystem
biodiversity
117
118 Figure 7-1: Conceptual Diagram of the Environmental Impacts of Biofuel
119 Feedstock Production
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
A air quality
A water quality
A ecosystem
biodiversity
(A water availability)
energy use
water use
chemical use
biofuel
product
activity
biofuel end use
biofuel production
LEGEND
environmental
impact
120
121 Figure 7-2: Conceptual Diagram of the Environmental Impacts of Biofuel
122 Production and Use
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
7.2.6 Scenarios
EPA's 2013 Report to Congress will assess the environmental impacts of all five stages
in the biofuel supply chain (Figure 2-3). One approach may be to create scenarios based on
volumetric biofuel requirements for 2022 as presented in the RFS2 (see Table 2-1). For example:
• Scenario A: 2022 RFS2-projected feedstock mix produced with comprehensive
conservation systems.
• Scenario B: 2022 RFS2-projected feedstock mix produced with existing levels of
conservation practice implementation.
• Scenario C: 2022 conventional feedstock mix (corn starch, corn stover, and
soybean) produced with existing levels of conservation practice implementation.
Figure 7-3 shows possible impacts in all six impact categories for these three scenarios
based on the feedstocks and fuels discussed in this Report. Scenarios are for illustrative purposes
only to show the potential rage of environmental impacts given assumptions about feedstock
production locations and practices; fuel production, transport, storage, and use patterns and
technologies; and target volumes (Appendix C, Table C-3). They do not necessarily represent the
most likely future developments in biofuel production systems. The magnitude, direction, and
certainty of bars (see figure legend) are based on expert interpretation of all available scientific,
peer-reviewed literature as of July 2010. Bars are relative to one another and do not reflect a
comparison with petroleum-based transportation fuel. Future versions of this Report to Congress
will expand and update this assessment.
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 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, since 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. While the continued use of corn starch for ethanol will likely
not change, the future profile of feedstocks and biofuels could vary from those
used in 2010, but which will actually be used and to what extent is highly
uncertain.
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
165
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Impact Category
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Production Volume
Water Quality
Water Quantity
Soil Quality
Air Quality
Biodiversity
Invasiveness
Sc. A: Envir. impacts
from 2022 RFS2
projected feedstock mix
produced with
conservation/ BMPs and
efficient technologies1
15 BG
BG
i
0.1 BG
7.9 BG
0.66 BG
BG
Sc. B: Envir. impacts
from 2022 RFS2
projected feedstock mix
produced with minimal
conservation/ BMPs and
current technologies1
15 BG
4.9 BG
I=ji
l=i>
J.
0.1 BG
7.9 BG
t=
l=
l=
t=
0.66 BG
l=
l=
l=
0.1 BG
Sc. C: Envir. Impacts from
2022 conventional
feedstock mix produced
with minimal
conservation/ BMPs and
current technologies1
15 BG
16 BG
!¦
I=
0 BG
0 BG
1.0 BG
0 BG
Bars represent total environmental impacts based on impacts from feedstock production on a per area basis;
fuel production, distribution, storage and use on a per volume basis; total volume produced; and assumptions of each
scenario fully described in Appendix C, Table C-3.
Legend
166
Maqnitude
Direction of Effect
Certaintv
(length of bar)
Negative effect
Negligible net effect
Positive effect
(shading)
Relatively large
1 1
O
1 1
Least certain
Moderate
1—i
O
1 1
Moderately certain
Relatively minor
*
•
*
Most certain
167 Figure 7-3: Cumulative Domestic Environmental Impacts of All Steps in the Biofuel Supply
168 Chain System under Three Scenarios in 2022
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
• 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 biorefineries 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 changing production practices from corn-soy rotations to corn-corn-
soy or even continuous corn production. 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, the 2013 assessment will include a several analyses
that provide important perspective for understand and evaluating the impacts of biofuel
production and use, as described below.
Comparison of Fossil Fuel to Biofuel. While this report provides a starting point for
comparing the relative impacts associated with a range of different biofuel feedstock and
production processes, it will also be useful 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 will 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 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 will 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 2013 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 be
addressed in the 2013 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
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Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022
213 the amount of co-products used in animal feed, which in turn displaces whole corn and soybean
214 meal used for the same purpose; the "displaced" energy is credited to the ethanol system and
215 offsets some of the energy required for production (Hammerschlag, 2006; Liska et al., 2008).
216 Market Impacts. Biofuels displace fossil energy resources, but also consume petroleum
217 products, natural gas, electricity (much of which comes from nonrenewable energy sources), and
218 even coal at different points along their supply chain. Consequently, changes in fossil fuel prices
219 will impact the economics of biofuel production in unpredictable ways. The 2013 assessment
220 will address market impacts and incorporate modeling of coupled energy systems and
221 agricultural markets.
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Chapter 8: References
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Whicker, JJ; Pinder, JE; Breshears, DD. 2008. Thinning semiarid forests amplifies wind erosion
comparably to wildfire: Implications for restoration and soil stability. Journal of Arid
Environments 72(4): 494-508.
White, EM. 2010. Woody biomass for bioenergy and biofuels in the United States—a briefing
paper. Gen. Tech. Rep. PNW-GTR-825. U.S. Department of Agriculture.
Wilkinson, M; Tepfer, M. 2009. Fitness and beyond: Preparing for the arrival of GM crops with
ecologically important novel characters. Environmental Biosafety Research 8: 1-14.
Williams, PR; Inman, DD; Aden, A; Heath, GA. 2009. Environmental and sustainability factors
associated with next-generation biofuels in the U.S.: What do we really know?
Environmental Science and Technology 43: 4763-4775.
Wiltsee, G. 1998. Urban waste grease resource assessment. NREL/SR-570-26141. National
Renewable Energy Laboratory. Available at:
http://www.biodiesel.org/resources/sustainability/pdfs/NREL%20Urban%20Waste%20G
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Winebrake, J; Wang, M; He, D. 2001. Toxic emissions from mobile sources: A total fuel-cycle
analysis for conventional and alternative fuel vehicles. Journal of the Air and Waste
Management Association 51: 1073-1086.
Wolt, JD. 2009. Advancing environmental risk assessment for transgenic biofeedstock crops.
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Wosten, JHM; van den Berg, J; van Eijk, P; Gevers, GHM; Giesen, WBJT; Hooijer, A; Idris, A;
Leenman, PH; Rais, DS; Siderius, C; Silvius, MJ; Suryadiputra, N; Wibisono, IT. 2006.
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forests. International Journal of Water Resources Development 22(1): 157-174.
Wright LL. 1994. Production technology status of woody and herbaceous crops. Biomass and
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Wu, M. 2008. Analysis of the efficiency of the U.S. ethanol industry. Center for Transportation
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Wu, M; Wang, M. 2006. Energy and emission benefits of alternative transportation liquid fuel
derived from switchgrass: A fuel life-cycle assessment. Biotechnology Progress 22(4):
1012-1024.
This document is a draft for review purposes only and does not constitute Agency policy.
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Yanowitz, J; McCormick, R. 2009. Effect of E85 on tailpipe emissions from light-duty vehicles.
Journal of the Air and Waste Management Association 59: 172-182.
Zah, R; Ruddy, TF. 2009. International trade in biofuels: An introduction to the special issue.
Journal of Cleaner Production 17: S1-S3.
Zavaleta, ES; Pasari, JR; Hulvey, KB; Tilman, GD. 2010. Sustaining multiple ecosystem
functions in grassland communities requires higher biodiversity. Proceedings of the
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Zhu, Y; Fox, RH. 2003. Corn-soybean rotation effects on nitrate leaching. Agronomy
Journal 95: 1028-1033.
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Appendix A
1 Appendix A
2
3 Glossary and Acronyms
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advanced biofuel: A renewable fuel, other than ethanol derived from corn starch that has life
cycle greenhouse gas (GHG) emissions that are at least 50 percent less than life cycle GHG
emissions from petroleum fuel. A 60-percent reduction in GHG is required from cellulosic
biofuels to get credit for being an "advanced" biofuel.
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: Any plant-like organisms that are usually photosynthetic and aquatic, but 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).
B100: Pure (i.e., 100 percent) biodiesel, also known as "neat biodiesel."
B20: A fuel mixture that includes 20 percent biodiesel and 80 percent conventional diesel and
other additives. Similar mixtures, such as B5 or B10, also exist and contain 5 and 10 percent
biodiesel, respectively.
Best Management Practices (BMPs): Best management practices are the techniques, methods,
processes, and activities 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.
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.
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.
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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.
cellulosic biofuel: A renewable fuel derived from lignocellulose (i.e., plant biomass comprised
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
separating the sugars from the residual material, mostly lignin, and then fermenting, distilling,
and dehydrating this sugar solution.
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.
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.
corn stover: The stalks, leaves, husks, and cobs that are not removed from the fields when the
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.)
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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, a U.S. farmer deciding to take land out of the Conservation Reserve Program in order
to grow more 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 (Public Law 110-140) (EISA): Signed into law 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.
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 used directly as a fuel and 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.
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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 1) tops, limbs, and other woody material not removed in forest
harvesting operations in commercial hardwood and softwood stands; and 2) woody material
resulting from forest management operations such as pre-commercial thinning and removal of
dead and dying trees.
forest thinning: Removal of residues from overgrown forests to reduce forest fire risk or
increase forest productivity. Residues are typically too small or damaged to be sold as round
wood but can be used as biofuel feedstock.
greenhouse gases: 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.
harvesting forest residue: See "forest thinning" above.
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.
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.
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invasive plants (also called invasives or noxious plants): An alien species 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 built environment such as fields, pastures, and settlements.
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.")
low-till: See "conservation tillage."
milling residues (primary and secondary): Wood and bark residues produced in processing (or
milling) logs into lumber, plywood, and paper.
mitigation: In the context of the environment, action to reduce adverse environmental impacts,
neat biofuel: See "B100."
net energy balance: In the context of biofuel, refers to the energy content in the resulting
biofuel less the total amount of energy used over the production and distribution process.
nitrogen fixation: The transformation of atmospheric nitrogen into nitrogen compounds that can
be used by growing plants. 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.
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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 means each of the following:
• Planted crops and crop residue from agricultural land cleared prior to December
19, 2007, and actively managed or fallow on that date.
• Planted trees and tree residue from tree plantations cleared prior to 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.
Renewable Fuels Standard (RFS) program: An EPA program created under the Energy Policy
Act (EPAct) 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 (EISA).
riparian forest buffer: An area of trees and shrubs located 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.
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sedimentation: The process of solids settling out of water due to gravity.
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 3 to
15 years. Examples include: hybrid poplars (Populus spp.), willow (Salix spp.), Loblolly pine
(Pinus taeda), and Eucalyptus.
soil erosion: The wearing away of land by the action of wind, water, gravity, or a combination
thereof.
soil organic matter: Decomposing plant and animal material in 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.
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.
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Appendix A
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325 woody biomass: Tree biomass thinned from dense stands or cultivated from fast-growing
326 plantations. This also includes small-diameter and low-value wood residue, such as tree limbs,
327 tops, needles, and bark, which are often by-products of forest management activities.
328
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Appendix B
Appendix B:
Summary of Selected Statutory Authorities
Having Potential Impact on the Production
and Use of Biofuels
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyelc
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Clean Air Act (CAA) (http://www.cpa.gov/air/caa/)
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 record keeping 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 for the transportation of 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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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Clean Water Act (CWA) (http://www.cpa.gov/watcrtrain/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 U.S. 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 storm water
and irrigation returns
flows are exempted from
NPDES permit
requirements.
Under Section 319, EPA
provides grants to states
to address non-point
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 discernable 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 U.S. 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."
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-3 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofucl Production, Transport, and Storage
Use of Biofucl
CWA: Section 404 Wetlands Program (www.cpa.gov/owow/wctlands/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.cpa.sov/lawsrcgs/laws/ccrcla.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 assure
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.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-4 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifecycle
Feedstock Production
and Transport
Biofucl Production, Transport, and Storage
Use of Biofucl
Emergency Planning and Community Right Know ACT (EPCRA) (http://www.cpa.gov/occaagct/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.
Section 302 requires facilities 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
facilities 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 their 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 (Toxics Release
Inventory) 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 the
EPA and to the state in which such facilities are
located.
Electric utilities are subject to
EPCRA Section 313 - Toxic Release
Inventory Reporting.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-5 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofucl Production, Transport, and Storage
Use of Biofucl
Federal Insectieide, Fungicide, and Rodcnticidc Act (FI.FRA) (http://www.cpa.gov/occaagct/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/rcgs and
http://www.fmcsa.dot.sov/safcty-sccurity/hazmat/sccurity-plan-guidc.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 that is 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 that is based on the assessment.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-6 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
National Environmental Policy Act (NEPA) (http://www.cpa.gov/compliancc/ncpa/)
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 (OPA) of 1990 (http://www.cpa.gov/lawsrcgs/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; and provides for requirements for spill
removal equipment. Oil Spill Plans must be in place
prior to operation, at facilities that have the potential to
spill oil to navigable waters.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-7 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccvclc
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Renewable Fuel Standard (RFS) (http://www.cpa.gov/otaq/fucls/rcncwablcfucls/indcx.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
lifecycle greenhouse gas (GHG)
performance threshold standards.
The GHG requirement is that the
lifecycle GHG emissions of a
qualifying renewable fuel must be
less than the lifecycle 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%); Advanced
Biofuel (50%); Biomass-based
Diesel (50%); and Cellulosic
Biofuel (60%).
If a facility produces 10,000 gallons or more of
renewable fuel per year, then it may participate in the
RFS program, though it is not required to do so. If a
facility chooses to participate in the RFS program, it
must satisfy the following criteria:
• Register
• Generate renewable identification
• Transfer RINs with fuel
• Provide product transfer documents
• Follow blending requirements
• Follow exporting requirements
• Follow non-road use of fuel
• Attest engagements
• Keep records for 5 years
• Report quarterly
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-8 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofuel Production, Transport, and Storage
Use of Biofuel
Resource Conservation and Recovery Act (RCRA) (http://www.cpa.gov/lawsregs/laws/rcra.html)
RCRA gives EPA the authority to
control hazardous waste generation,
transportation, treatment, storage,
and disposal of hazardous waste.
Facilities that handle hazardous
waste are required to obtain an
operating permit from the state
agency or EPA. RCRA regulates
USTs.
Regulatory issues related to waste generated by biofuel
production - solid and hazardous waste 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 biofuels spills.
UST leak detection and prevention
are required.
Safe Drinking Water Act (SDWA) (http://www.cpa.gov/ogwdw/sdwa/)
The 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.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-9 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofucl Production, Transport, and Storage
Use of Biofucl
Safe Drinking Water Act: Underground Injection Control (UIC) Program (http://www.cpa.gov/safcwatcr/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 storm water, cooling water,
industrial or other fluids into the subsurface via an
injection well;
• It has an on-site sanitary waste disposal system
(e.g., septic system) that serves or has the capacity
to serve 20 or more persons;
• It has an on-site sanitary waste disposal system that
is receiving other than a solely sanitary waste stream
regardless of its capacity; or
• 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 Countcrmeasurc (SPCC) and Facility Response Plans (FRP) (http://www.cpa.gov/ocm/contcnt/spcc/indcx.litm)
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 Facility
Response Plan (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 US) to
prepare and implement an
SPCC Plan.
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 U.S. or
adjoining shorelines.
• Secondary containment cannot be provided for all
regulated oil storage tanks.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-10 DRAFT—DO NOT CITE OR QUOTE
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Appendix B
Table B-l: Summary of Selected Statutory Authorities Having Potential Impact on the Production and Use of Biofuels
Summary of Statute/Program
Stage of Lifccyclc
Feedstock Production
and Transport
Biofucl Production, Transport, and Storage
Use of Biofucl
Toxic Substances Control Act (TSCA) (http:/Avww.cpa.;»ov/lawsrcj»s/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 biofuels
feedstocks.
Mandatory notification and approval for new
chemicals and new biological products, prior to
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.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 B-l 1 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Appendix C
Basis for Figures 6-1, 6-2, and 7-3
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-l DRAFT—DO NOT CITE OR QUOTE
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Appendix C
4 This appendix presents three tables, Tables C-l, C-2, and C-3, which summarize the information providing the basis for
5 Figures 6-1, 6-2, and 7-3, respectively. For each of the six feedstocks included in this report, Tables C-l and C-2 briefly describe the
6 current production status (Background), as well as the conditions anticipated to result in the most negative environmental effect (Most
7 Negative Future Scenario) and the most positive environmental effect (Most Positive Future Scenario) in each of the environmental
8 media considered. Table C-3 describes the basis for the three scenarios included in Figure 7-3.
9
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Corn Starch
Most current corn
feedstock cultivation for
biofuel production is a
result of either 1)
displacing soy production,
2) diverting existing corn
grain to processing for
fuel, or 3) placing former
agricultural land back into
production.
Water Quality
Corn grown with conventional tillage and
liigli chemical inputs replaces lands in the
Conservation Reserve Program (CRP).
Corn grown with comprehensive
conservation practices replaces corn grown
with existing production systems.
Water Quantity
Irrigated corn replaces non-irrigated land
use in drier area.
Production of non-irrigated corn.
Soil Quality
Corn grown with conventional tillage and
high chemical inputs replaces lands in the
Conservation Reserve Program (CRP).
Corn grown with comprehensive
conservation practices replaces corn grown
with existing production systems.
Air Quality
Irrigated corn grown with conventional
tillage and high chemical inputs replaces
lands in the Conservation Reserve Program
(CRP).
Corn grown with comprehensive
conservation practices replaces corn grown
with existing production systems.
Biodiversity
Corn grown with conventional tillage and
high chemical inputs replaces lands in the
Conservation Reserve Program (CRP).
Corn grown with comprehensive
conservation practices replaces corn grown
with existing production systems.
Invasiveness
Negligible known effect.
Negligible known effect.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-2 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Most current soybean
biofuel production comes
from increased allocation
of existing harvest to
Water Quality
Soy replaces lands in the Conservation
Reserve Program (CRP).
Soy grown with comprehensive conservation
practices replaces corn grown with
conventional tillage and high chemical
inputs.
biodiesel.
Water Quantity
Irrigated soy replaces non-irrigated land
use in drier area.
Non-irrigated soy replaces irrigated corn.
a
a
^.
Soil Quality
Soy replaces lands in the Conservation
Reserve Program (CRP).
Soy grown with comprehensive conservation
practices replaces corn grown with
conventional tillage and high chemical
inputs.
o
00
Air Quality
Irrigated soy replaces non-irrigated land
use in drier area.
Non-irrigated soy grown with comprehensive
conservation practices replaces corn grown
with conventional tillage and high chemical
inputs.
Biodiversity
Soy replaces lands in the Conservation
Reserve Program (CRP).
Soy grown with comprehensive conservation
practices is diverted from existing production
systems.
Invasiveness
Negligible known effect.
Negligible known effect.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-3 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Not currently produced
commercially for biofuel
feedstock.
Water Quality
High rate of stover removal on highly
erodible land.
Appropriate rate of stover removal to
minimize erosion given site-specific
characteristics and management practices.
O
-t—>
pj
Water Quantity
High rate of stover removal on irrigated
land in drier areas.
Appropriate rate of stover removal to
minimize additional irrigation given site-
specific characteristics and management
practices.
Soil Quality
High rate of stover removal on highly
erodible land with low organic matter soil.
Appropriate rate of stover removal to
minimize erosion given site-specific
characteristics and management practices.
u
o
U
Air Quality
High stover removal requires additional
harvesting pass and increased subsequent
fertilizer applications.
Appropriate rate of stover removal to
minimize subsequent fertilizer applications;
stover removed with corn in a single
harvesting pass.
Biodiversity
High rate of stover removal on highly
erodible land that results in sedimentation
to aquatic systems.
Appropriate rate of stover removal to
minimize erosion given site-specific
characteristics and management practices.
Invasiveness
Negligible known effect.
Negligible known effect.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-4 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Woody Biomass
Not currently produced
commercially for biofuel
feedstock.
Water Quality
Short-rotation woody crops (SRWC) with
short replanting intervals and high
chemical inputs, and without coppicing
replace mature, managed tree plantations.
Short-rotation, coppiced woody crops with
long replanting intervals, and low chemical
inputs replace non-coppiced, managed forests
with short replanting intervals, and high
chemical inputs.
Water Quantity
Irrigated SRWCs are grown in drier
regions.
Production of non-irrigated SRWC in wetter
regions.
or
Low to moderate rate of forest residue
removal or thinning.
Soil Quality
SRWC with short replanting intervals and
without coppicing replace mature,
managed tree plantations.
Short-rotation, coppiced woody crops with
long replanting intervals, and low chemical
inputs replace non-coppiced, managed forests
with short replanting intervals, and high
chemical inputs.
Air Quality
SRWC with short replanting intervals, high
chemical inputs, high isoprene emissions,
and without coppicing replace mature,
managed, low-isoprene emitting tree
plantations.
Short-rotation, coppiced woody crops with
long replanting intervals, low chemical
inputs and low isoprene emissions replace
non-coppiced, managed forests with short
replanting intervals, high chemical inputs,
and high isoprene emissions.
Biodiversity
SRWC with short replanting intervals and
high chemical inputs, and without
coppicing replace mature, managed tree
plantations.
Long rotation woody crop stands replace
SRWC with short replanting intervals and
high chemical inputs.
Invasiveness
Woody species (e.g., E. grandis) are grown
and become invasive.
Production and harvesting of non-invasive
woody species.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-5 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Not currently produced
commercially for biofuel
feedstock.
Water Quality
Perennial grasses established with
conventional tillage and grown with a short
planting interval and chemical inputs
replace land in the CRP.
Perennial grasses established with no till
grown with low chemical inputs and a long
replanting interval replace corn grown with
conventional tillage and high chemical
inputs.
Water Quantity
Irrigated perennial grasses replace non-
irrigated land use in drier regions.
Non-irrigated perennial grasses replace
irrigated corn.
Xfl
cn
o
Soil Quality
Perennial grasses established with
conventional tillage and grown with a short
planting interval and chemical inputs
replace land in the CRP.
Perennial grasses established with no till with
a long replanting interval replace
conventionally tilled row crops.
• T-H
s
-------
Appendix C
Table C-l: Basis for Figure 6-1 (Maximum Potential Range of Environmental Impacts [on a Per Unit Area Basis] Resulting
from Cultivation and Harvesting of the Six Biofuel Feedstocks Considered in this Report)
Background
Impact Category
Conditions for Maximum
Potential Negative Environmental
Impact
Conditions for Maximum Potential
Positive Environmental Impact
Algae
Not currently produced
commercially for biofuel
feedstock.
Water Quality
Untreated effluent, from growing algae is
discharged to the environment.
Algae arc grown with wastewater: treated
effluent is recycled for further use.
Water Quantity
Algae are grown in drier regions (e.g.,
Southwest) with freshwater in open ponds.
Algae are grown with wastewater in closed
bioreactors; treated effluent is recycled for
further use.
Soil Quality
Negligible known effect.
Negligible known effect
Air Quality
Algae grown with added nutrients.
Algae grown with nutrients in wastewater.
Biodiversity
Negligible known effect.
Negligible known effect.
Invasiveness
Invasive algae species grown in open
ponds escape and proliferate.
Production of non-invasive algae species in
closed bioreactors.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-l DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-2: Basis for Figure 6-2 (Maximum Potential Range of Environmental Impacts [on a Per Unit Volume Basis] Resulting
from Ethanol and Biodiesel Production, Transport, Storage and Use)
Background
Impact Category
Conditions for Maximum
Potential Negative
Environmental Impact
Conditions for Maximum
Potential Positive Environmental
Impact
Corn Ethanol
As of 2009. 180 corn ethanol facilities
were operating in the U.S., mostly in the
Midwest. Future corn ethanol production
is expected to expand in the same region.
Water Quality
Effluent with high biological
oxygen demand (BOD); Dried
Distillers Grain (DDG) byproduct
fed to livestock with inadequate
waste management practices;
under-ground storage tanks (UST)
leak.
Effluent effectively treated for BOD:
DDG-fed livestock waste incorporated into
comprehensive nutrient management plan;
USTs do not leak.
Water Quantity
3-6 gallons of water required per
gallon of ethanol produced.
Improvement in water use efficiency and
recycling.
Air Quality
Ethanol facility powered by coal.
Ethanol facility powered by natural gas.
Soybean
Biodiesel
In 2009, 191 biodiesel facilities were
operating in the U.S., many producing
under their capacity.
Water Quality
Effluent with high BOD, total
suspended solids (TSS) and
glycerin content.
Effluent effectively treated for BOD, TSS
and glycerin.
Water Quantity
<1 gallon of water required per
gallon of biodiesel produced.
<1 gallon of water required per gallon of
biodiesel produced.
Air Quality
Biodiesel facility powered by coal.
Biodiesel facility power by natural gas.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-8 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-2: Basis for Figure 6-2 (Maximum Potential Range of Environmental Impacts [on a Per Unit Volume Basis] Resulting
from Ethanol and Biodiesel Production, Transport, Storage and Use)
Background
Impact Category
Conditions for Maximum
Potential Negative
Environmental Impact
Conditions for Maximum
Potential Positive Environmental
Impact
Cell ul osic
Ethanol
As of 2009. there were no commercially
operating cellulosic ethanol facilities in
the U.S. There is uncertainty about when
and where the first facilities will start
producing.
Water Quality
Effluent possiblv with high BOD:
USTs leak.
Effluent effectively treated for BOD: USTs
do not leak.
Water Quantity
10 gallons of water required per
gallon of cellulosic ethanol.
Improvement in water use efficiency and
recycling.
Air Quality
Ethanol facility powered by coal.
Ethanol facility powered by natural gas.
11
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-9 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-3: Description of Scenarios in Figure 7-3 (Cumulative Domestic Environmental Impacts of All Steps in the Biofuel
Supply Chain System under Three Scenarios in 2022)
Feedstock
Scenario A
2022 RFS2-projccled feedstock mix produced with
conservation/best management practices (BMPs) and efficient
technologies
Scenario B
2022 RFS2-projecled feedstock mix
produced with minimal
conscrvation/BMPs and current
technologies
Scenario C
2022 conventional feedstock mix (corn
starch, corn stover, and soybean)
produced with minimal
conscrvalion/BMPs and current
technologies
Conventional Ethanol
15 BG
• No decrease in crop rotation with soybeans.
• Increased use of continuous corn production and reduction in crop rotation.
o
J-H
00
• Increases in grain yield primarily due to breeding new
varieties that also require fewer production inputs, including
fertilizer, pesticides, and irrigation.
• Increased grain yields using greater production inputs, including fertilizer,
pesticides, and irrigation.
• No conversion of marginal lands to corn production.
• Conversion of marginal land to corn production, including in areas that
require irrigation.
o
o
• Increased use of conservation practices, including
conservation tillage, nutrient management, and efficient
irrigation delivery.
• No increases in conservation practices.
• Increased fuel conversion efficiency and reductions in fuel
production inputs, including fresh water.
• No increases in fuel conversion efficiency nor reductions in fuel production
inputs.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-10 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-3: Description of Scenarios in Figure 7-3 (Cumulative Domestic Environmental Impacts of All Steps in the Biofuel
Supply Chain System under Three Scenarios in 2022)
Feedstock
Scenario A
2022 RFS2-projccled feedstock mix produced with
conservation/best management practices (BMPs) and efficient
technologies
Scenario B
2022 RFS2-projecled feedstock mix
produced with minimal
conscrvation/BMPs and current
technologies
Scenario C
2022 conventional feedstock mix (corn
starch, corn stover, and soybean)
produced with minimal
conscrvation/BMPs and current
technologies
Ccllulosic Ethanol
Corn
Stover
4.9 BG
16 BG
• Stover harvest limited to acreage with low erosion potential,
or erosion is mitigated with conservation tillage.
• Stover harvested with single-pass harvester.
• Increased use of conservat ion practices.
• Stover harvested on acreage
regardless of erosion potential.
• Stover harvested with multi-pass han
• No increase in use of conservation pr
/ester,
acticcs.
Woody
Biomass
0.1 BG
0 BG
• Biomass produced via light-lo-modcralc forest thinning or
from short-rotation woody crops cultivated with long
planting intervals on non-federal land currently in managed
forest with short planting intervals.
• Short-rotation woody crops with
short planting intervals and high
chemical inputs cultivated on non-
federal land currently in mature,
managed forest plantations.
Perennial Grass
7.9 BG from dedicated energy crops
0 BG
• Switchgrass production area limited to east of Rockv
Mountains.
• Conversion of land currently in row crop production to
switchgrass production.
• Conversion of low diversity, marginal land to conservation
managed switchgrass production.
• Increased fuel conversion efficiency and reductions in fuel
production inputs, including fresh water.
• Ccllulosic feedstock (switchgrass or
Miscanthus) produced on marginal
land requiring high production
inputs, including fertilizer,
pesticides, and irrigation.
• No increases in fuel conversion
efficiency or reductions in fuel
production inputs, including fresh
water.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-l 1 DRAFT—DO NOT CITE OR QUOTE
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Appendix C
Table C-3: Description of Scenarios in Figure 7-3 (Cumulative Domestic Environmental Impacts of All Steps in the Biofuel
Supply Chain System under Three Scenarios in 2022)
Feedstock
Scenario A
2022 RFS2-projccled feedstock mix produced with
conservation/best management practices (BMPs) and efficient
technologies
Scenario B
2022 RFS2-projecled feedstock mix
produced with minimal
conscrvation/BMPs and current
technologies
Scenario C
2022 conventional feedstock mix (corn
starch, corn stover, and soybean)
produced with minimal
conscrvalion/BMPs and current
technologies
Biomass-bascd Diesel
Soybean
0.66 BG
1 BG
• increases in yield primarily due to breeding new varieties
that also require fewer production inputs, including
fertilizer, pesticides, and irrigation.
• No conversion of marginal lands to soybean production.
• Increased use of conservation practices, including
conservation tillage, nutrient management, and efficient
irrigation delivery.
• Increases in yield primarily due to higher production inputs, including
fertilizer, pesticides, and irrigation.
• Conversion of marginal lands to soybean production, including areas
requiring irrigation.
• No increase in use of conservation practices (i.e., conservation tillage,
nutrient management, and efficient irrigation delivery).
Algae
0.1 BG
0 BG
• Algae production co-located with stationary carbon dioxide
source on marginal land.
• Nutrient inputs from wastewater or other waste sources.
• Closed bioreactors co-located with publicly owned
treatment works and other wastewater treatment facilities.
• Algae produced on land converted
from natural cover.
• Large nutrient inputs from non-
waste sources.
• Open pond production using fresh
water.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 C-12 DRAFT—DO NOT CITE OR QUOTE
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Appendix D
1 Appendix D:
2
3 Conceptual Models
4
5
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-l DRAFT—DO NOT CITE OR QUOTE
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6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
Appendix D
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 2013
Report to Congress. The conceptual models presented in this appendix lay a foundation for this
future effort. Figures D-l to D-7 present conceptual models for feedstock cultivation and harvest.
Figures D-8 and D-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 and, while
comprehensive, 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, either in terms of 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 - particulate matter
• T & E species- threatened and endangered species
• VOC - volatile organic compound
Feedstock Production
Figures D-l to D-7 present seven models for the six feedstocks covered in this report:
corn starch; soybean; corn stover; perennial grass; woody biomass (short-rotation woody crops
and forest thinning/residue removal); and algae production.
Different pathways are introduced at the top of several of these feedstocks 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
This document is a draft for review purposes only and does not constitute Agency policy.
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32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
Appendix D
information. Dotted boxes without arrows depict highly uncertain impacts that nonetheless are
described in the literature.
Fuel Production and Distribution
Figures D-8 and D-9 present conceptual models for production and distribution of the
two biofuels covered in this report: ethanol and biodiesel.
Ethanol Production
Figure D-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 the Figure D-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 vary slightly in
terms of their chemical processes and by-products. As with Figures D-l to D-7, a dotted border
is used to denote impacts with relatively large uncertainty due to a lack of information.
Biodiesel Production
Figure D-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 by-product.
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-3 DRAFT—DO NOT CITE OR QUOTE
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Appendix D
4, CRP/pasture land
(Pathway 2)
T corn
yield/proportion of
crop to energy
(Pathway 3)
¦4/ soy production
(Pathway 1)
T corn production
tile
drainage
pesticide
application
fertilizer
application
irrigation
harvest
wcorn starch
feedstock
transport
0(3), 1(1,2)
fertilizer usage
0(3), 1[1,2)
pesti cide
usage
mi 1(1,2)
fuel usage
&{3l Ml), T(1,2)
ground & surface
water usage
®(3), T(1,2)
nutrient
contamination
0(1,3), 1 (1,2}
fugitive dust
0(3), 1(1,2)
SO., NQ^ VOC
CO, PM
emissions
0(3), T (1,2)
CO. emissions
0(1,3), M2)
wetlands
0(3), 1(1,2)
pesti cide
contamination
4^ fo re ste d/gra ssl a n d
riparian buffers
0(3), 1(1),
Ml,2)
0 3), 1 (1,2)
water
benzene
0(3), 1(1,2) BOD &
hypoxia
availability
0(3), MD
1(1,2)
soil erosion
aero ein
0(1,3), M2)
habitat
availability
e Ti ss o ns
0(3), 1(1)
Ml,2}
soil organic
matter
0(3), Ml), 1(1,2)
sedimentation
0(3), 4>(1,2)
air quality
0(1,3), M2)
water purification
I natural pest&
pathogen control
LEGEND
environmental
parameters
0(3), 1(1),
Ml,2)
soil fertility
activity1
microbial
diversity
0(1,3), M2)
flood control potential
Dotted= i
Uncertain
impact due to
lack of data
ecosystem
services
product
0(1,3), Ml,2)
T & E species
support
0(3), Ml,2)
aquatic life use
support
1
0(3), Ml,2)
water
quality
lanted=conne
to next diagra
biotic
responses
0(1,3), Ml,2) K
T & E species
0(1,3), M2)
diversity & abundance of
terrestrial biota
0(3), Ml2)
I diversity & abundance of
^ aquatic biota
0,-X- or 1 and numbers al ongsi de refer to
directionality of effects resulting from numbered
scenarios depicted at top of figure.
Figure D-l: Pathways for Potential Environmental Impacts of Corn Starch Feedstock Cultivation
This document is a draft for review purposes only and does not constitute Agency policy.
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Appendix D
4- corn production,
(Pathway 1)
4, CRP/pasture land
(Pathway 2)
1 soy production
1 soy
¦ yield/proportion of
crop to energy
(Pathway 3)
tile
drai nage
irrigation
tillage
pesticide
application
fertilizer
application
¦¦l fo re ste d/gra ssl a n d
riparian buffers
0(1,3), MZ}
wetlands
—
| 0(1,3), M2) 1
0(1,3), M2)
1 habitat 1
habitat
j connectivity J
availability
0(3), Ml), 1*11,2)
ground and surface
water usage
J 0(3), 'f(l),
I Ml,2)
j water
availability'
0(3), Ml), 1(2)
pesticide usage
0(3), MD, 1(2)
fertilizer usage
I natural pest&
1 pathogen control
. __J,
0(2, J), 442) ,
water purification
I
I
v_ J
0(31 Ml), 1(2)
pesti cide
contamination
0(3), Ml), 1(2) ,
nutrient
contamination
harvest
>/ soybean
feedstock
transport
0(3), Ml), 1(2)
fuel usage
0(3), 1{l,2)f Ml)
fugitive dust
0(3), Ml), 1(2) CO
emissions
0(3), 1(1),
Ml2)
soil organic
matter
0(3), MD,
1(1,2)
soil erosion
0(3), Ml), 1(2) BOD
& hypoxia
0(3), MD,
¦T(2) benzene,
acrol ein
emissions
0(3), Ml), 1(2)
S02, NO^ VOC, CO
PM emissions
I
0(3), Ml), 1(1,2)
sedimentation
0(3), t(l), M2)
air quality
LEGEND
, 0(1,3), M2)
j flood control potential
^
0(13}, M2) I
diversity & abundance of k-
terrestrial biota
0(3), -t(1),
Ml,2)
„ soil fertility
0(1,3), 1(1), M2)
T & E species
support
1m 4,(2} ^
. T & E species \
microbial
diversity
activity
environmental
parameters
product
0(3), 1(1),
M2)
water quality
0(3), 1(1), M2)
aquatic life use
support
:l ante d= con ne
to next diagrai
f
ecosystem
services
biotic
responses
Dotted= I
Uncertain
impact due to '
lack of data 1
J 0(3), 1(1), M2)
j diversity & abundance of
^ aquatic biota
0, 4^ or -f and numbers alongside refer to
directionality of effects resulting from numbered
scenarios depicted at top of figure.
Figure D-2: Pathways for Potential Environmental Impacts of Soybean Feedstock Cultivation
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-5 " DRAFT—DO NOT CITE OR QUOTE
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Appendix D
-Is com production
storage
tile
drainage
pestidde
application
fertilizer
application
tillage
harvest
stover removal
-ycorn stover
/ feedstock
'transport.
^ fuel usage
3,1s fertilizer usage
fin 5(sb5&j. yrs.)
0,/fs ground &
surface water usage
(m subsaj. yrs.)
0,t nutrient
contamination
t- C02.. NO„ VOC, CO,
S02, PM emissions
fugitive
dust
0,'T' benzene,
acrol ein
0, -l- water |
availability |
hypoxia
0, t
soil erosion
4-soil organic
matter
0, -f - sedimentation
0 A", ^
air quality
-f soil
compaction
4- soil
fertility"
4/ microbial
diversity
LEGEND
environmental
parameters
activity
Dotted=
Uncertain
impact due to
lack of data
0, 4- T & E
spedes support
0, 4 aquati c I ife
use support
0, 4 diversity & abundance |
of aquatic bi ota
ecosystem
product
water
quality
x:
£1 ante d= con nei
to next diagrarr
biotic
responses
i, 4 diversity & abundance k-
of terrestrial biota
0, sj, or -T and numbers alongside refer to
directionality of effects resultingfrom numbered
scenarios depicted at top of figure.
Figure D-3: Pathways for Potential Environmental Impacts of Corn Stover Feedstock Cultivation*
*Com stover is a waste product of corn starch cultivation. The impacts of corn cultivation are shown in Figure D-l. Figure D-3 highlights the
environmental impacts of stover removal above and beyond those impacts attributable to corn grain production.
This document is a draft for review purposes only and does not constitute Agency policy.
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Appendix D
4, CRP/pasture land
(Pathway 2)
4/ corn/soy
production
(Pathway 1)
T perennial grass production
transport
perennial
pesticide
application
fertilizer
application
irrigation
harvest
feedstock
transport
y
j-T• (1,2), 0(1,2} \
I weeds & r~^
weed &
nvas v e
Mnvasive grass |
Ml), T{1,2)
fuel usage
Ml), Tf2), 0(2)
fertilizer usage
control
I MD,t{2)f0{2)
I ground & surface
water usage
Ml), T(12)f
pesticide usage
T(2l Ml)
fugitive
dust
weeds
4/ forested
¦I, wetlands
ripanan
Mi), i (2), m)
nutrient
contamination
buffers
•t {l,2)t 0(2)
ow^ diversity
grassland
habitat
Ml), r{2) so
NO , VOC, CO PM
emissions
Ml), Tf2) CO
emissions
Ml), T{1,2)
0(2) pesticide
contamination
MD, T(2),
m
benzene,
acrol ein
t (i), sim,
water
Ml), T{2), 0(2)
BOD & hypoxia
availability
Mil T{2)
im
soil erosion
erni55tons
til), 0(2)
soil organic
matter
I tM, MZ). |
I 0(2) habitat
T (1), |
Ml,2), 0(2) |
habitat I
Ml), M2)
air quality
water
purification
connectivity
Ml), T(2), 0(2}
sedimentation
availability I
LEGEND
MD, M2)
natural pest &
pathogen control
environmental
parameters
activity
r(i), 0(2)
soil fertility
' Dotted= I
Uncertain
impact due to
lack of data 1
microbial
diversity
ecosystem
services
product
I flood control potential j
_ _y.
[ tffl, M2),
0(2)
t {1,2), M12),
=J 0(2)
( T & E species
' support j
I 1(1,2), 4,(1,2), '
r \
tII), 4,(21, 0(2) aquatic
lanted=conne
to next diagra
biotic
responses
water
quality
t (1,2), Ml,2), 0(2)
I .. , , r
. 0(2)
T & E species J
diversity & abundance of
terrestrial biota
life use support
i:
t(l), M2), 0(2) diversity &
abundance of aquatic biota
0, 4/ or t and numbers alongside refer to
directionality of effects resulting from numbered
scenarios depicted at top of figure.
Figure D-4: Pathways for Potential Environmental Impacts of Perennial Grass Feedstock Cultivation
This document is a draft for review purposes only and does not constitute Agency policy.
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Appendix D
4, CRP/pasture land*
(Pathway 2)
•Jx corn/soy
production*
(Pathway 1)
vjz managed, non-federal
forest (Pathway 3)
T SRWC production
transport
pesticide
application
fertilizer
application
irrigation
woody
harvest
biomass
feedstock
transport
I invasive trees | ^
invasive
tree
control
Mil T(2,3)
fuel usage
Ml), T(2,3)
fertilizer usage
_jy
to
in vnsi yss
(zee left) ,
I Mlir{2,3),m
I ground & surface
I water usage
s1(1), -t (2,3)
pesticide usage
-1(1).. T(2,3)
[fugitive dust!
grasslands
¦I, wetlands
Ml), T(2,3), m)
nutrient
contamination
Ml), T(2,3)
SO-,, NO^ VOC
CO, PM
emissions
Ml}, t(2,3)
CO., emissions
T(l,2), 0(3)
low-diversity
forest habitat
Ml), T(2,3)
pesticide
contamination
Ml), t(2,3)
m
I water
1 availability
benzene
aero ein
emissions
I -Ml), f(2,3), 0(2)
I BOD & hypoxia j
Mlh T(2,3)
m)
soil erosion
t (D,-1(2,3)
0(1,2)
soil organic
matter
|t (1,2), M2,3) I
I 0(3) habitat
T (1,2), |
M2), 0(3) I
habitat I
T(l), -l (2,3)
air quality
water
I connectivity |
Ml), T(2,3), 0(1}
sedimentation
purification
availability I
LEGEND
environmental
parameters
natural pest &
pathogen control
act vi ty
Ml}, -I (2,3), i
0(1,2) soil k
fertility
Dotted= "
Uncertain
impact due to
lack of data 1
microbial
diversity
ecosystem
services
product
I flood control potential j
¦f(l), U2,3), l
m
I water
1 quality f
1
t (1), M2,3), 0(3)
aquatic life use
support
Ml,2), M2,3),
^ 0(3}
1 T & E species
' support j
I -T(l,2), M2,3), 1
lanted=conne
to next diagra
biotic
responses
) 0(2,3)
T & E species J
1,2), M2,3), 0(2,3)
diversity & abundance of
terrestrial biota
* tfl), -U2,3), 0(3) diversity &
abundance of aquatic biota
0, or t and numbers alongside refer to
directionality of effects resulting from numbered
scenarios depicted at top of figure.
Figure D-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.
This document is a draft for review purposes only and does not constitute Agency policy.
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Appendix D
'f forest residue removal
(Pathway 1)
•T forest thinning
(Pathway 2)
[ 0 j
I ground & surface |
I water usage |
I water I
' availability I
v L.j
j A* habitat I
. availshilitv I
1s ah 0 m
soil erosion
^(Ih 0 (2)
sedimentation
| ±{lh®{l,2) I
I soil organic matter J
{ -i-(110(1,2) J
l soil fertility \
-------
Appendix D
4- natural land cover
4, marginal land cover
•T- algae culture
r —
I'f'invasivel
I algae r~
I invasive
j algae
control
pond/aqueous
pesti cide
nutrient
co2
bi oreactor fill
application
application
provision
j'T" wastewaterj j •T' pesticide |
I -t* nutrient")
, L
—1 1—i—j 1
r n
1 -Is ground & j
i
1 surface waterl
i i
i i
1 -T" pesticide j
usage
i
j
1 contamination 1
"T"J ,i
I 4- habitat | j 4^ habitat i
connectivity | (availability'
4/ water
availability
"T
J
1:::
I T, 4- BOD & 1
I hypoxia '
'"T"
harvest/dewater
feedstock
I T fuel & 1
I energy usage I
T. 4- CO
emissions
CO, PM
emissions
T, 4- aif
quality
1 "t, 4- water
J 4- T&E |
^nprip<: ^ijnnnrt l~
—I J quality
I
I species support
4, diversity &
J abundance of terrestrial
biota
'f f 4- T&E
species
quality
:j:
¦T, 4- aquatic life
use support
activity
environmental
parameters
product
ecosystem
services
¦f, 4' diversity &
abundance of aquatic
biota
£1 ante d= conned
/to next diagram
' Dotted= I
Uncertain I
t impact due to
biotic
responses
0, 4- or ^ and numbers alongside refer to
directionality of effects resulting from numbered
scenarios depicted at top of figure.
Figure D-7: Potential Environmental Impacts of Algae Feedstock Production
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-10 DRAFT—DO NOT CITE OR QUOTE
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Appendix D
£orn starch j
feedstock r
conversion of
starch to ethanol
f cell ulosic
feedstock j
LEGEND
activity
environmental
parameters
product
ecosystem
sen/ices
<^by-product^>
biotic
responses
;| ante d= con ne
to next diagrai
f\
Dotted= I
Uncertain
impact due to '
lack of data '
0, 4/ or 1s and numbers alongsi de
refer to directionality of effects
resulting from numbered scenarios
depicted at top of figure.
milling (wet or dry)
m
starch hydrolysis
I ~
glucose
fermentation
"f- groundwater
usage
X
/dry-di still ers^
X
conversion of cellulose
to ethanol
catalysis
(ex., acid)
thermochemical
conversion
biochemical
conversion
chemical usage
T' energy usage
"T4 process & waste
water discharge
1 4, water I
'v _availa^ility_ J
't4 BOD & hypoxia
^ chemical
contamination
4, T & E species
support |
4^ water
quality
ethanol
lignin
.»<' bioc har^X
t S02. NOx,
VOC, CO, PM
emissions
"T* ethanol
vapor
-i- aquatic life use support I
'i
I
4^ air quality
j 4, T & E species J
4, diversity & abundance of aquatic biota
) ¦)/cell ul osic
\ diesel
5 by-product stora
ge
1
by-product transp
ort
ethanol
storage
ethanol
transport
•T fuel usage
Figure D-8: Potential Environmental Impacts of Producing and Distributing Conventional and Cellulosic Ethanol
(Impacts of Fuel Use Not Included)
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-ll DRAFT—DO NOT CITE OR QUOTE
-------
Appendix D
oybean/algae •
feedstock /
oil extraction
LEGEND
activity
environmental
parameters
product
ecosystem
sen/ices
<^by-product^>
biotic
responses
;| ante d= con ne
to next diagrai
f\
Dotted= I
Uncertain
impact due to '
lack of data '
0, 4/ or 1s and numbers alongsi de
refer to directionality of effects
resulting from numbered scenarios
depicted at top of figure.
conversion of oil to biodiesel
algae carbs.&
protein
soybean meal
hydrogenation
catalytic cracking
trans-
esterification
¦T- groundwater usage
¦f chemical
usage
energy
usage
't- process &
waste water
discharge
glycerin
. byproduct
byproduct
storage
transport
biodiesel
biodiesel
storage
biodiesel
transport
¦t SOj, NO^
VOC, CO, PM
emissions
1s fuel
usage
T total
suspended
so ids
t BOD &
hypoxia
' 4, water I
J availability J
•f-chemical
contamination
j 4/ T&E species
4/ air quality
support
i ^ -j
I 4, T&E species I
4' water
quality
4, aquatic life use
support
j 4^ diversity & abundance J
of aquatic biota
Figure D-9: Potential Environmental Impacts of Producing and Distributing Biodiesel
(Impacts of Fuel Use Not Included)
This document is a draft for review purposes only and does not constitute Agency policy.
1/19/11 D-12 DRAFT—DO NOT CITE OR QUOTE
------- |