DRAFT EPA/600/R-10/183A 

DO NOT CITE OR QUOTE January 2011 

 External Review Draft

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 
 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 DRAFT—DO NOT CITE OR QUOTE

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. 
Executive Summary

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 i DRAFT—DO NOT CITE OR QUOTE

1 EXECUTIVE SUMMARY

 2 

3 This report is the first of the U.S. Environmental Agency’s (EPA’s) triennial reports to 

4 Congress required under the 2007 Energy Independence and Security Act (EISA). EISA requires 

5 EPA to revise the Renewable Fuel Standard (RFS) program to increase the volume of renewable

6 fuel blended into transportation fuel from 9 billion gallons per year in 2008 to 36 billion gallons 

7 per year by 2022. The revised standards (RFS2), finalized in 2010, establish new specific annual 

8 volume requirements for cellulosic biofuel, biomass-based diesel, advanced biofuel, and total

9 renewable fuel in transportation fuel. 

10 EISA Section 204 calls for EPA to report to Congress on the environmental and resource 

11 conservation impacts of increased biofuel production and use, including air and water quality, 

12 soil quality and conservation, water availability, ecosystem health and biodiversity, invasive 

13 species, and international impacts. This report reviews impacts and mitigation tools across the 

14 entire biofuel supply chain, including feedstock production and logistics, and biofuel production, 

15 distribution, and use. The report focuses on: 

16 • Six feedstocks: The two most predominantly used (corn starch and soybeans), 

17 and four others (corn stover, perennial grasses, woody biomass, and algae) that 

18 represent a range of feedstocks currently under development. Because the RFS2 

19 limits the amount of corn starch-derived biofuel that counts toward the volume 

20 requirement in 2022 to 15 billion gallons, an increased reliance on other 

21 feedstocks is predicted.

22 

23 • Two biofuels: Ethanol (both conventional and cellulosic) and biomass-based 

24 diesel, because they are the most commercially viable in 2010 and/or projected to 

25 be the most commercially available by 2022.

 26 

27 This first report represents peer-reviewed information available through July 2010 and 

28 reflects the current uncertainty about biofuel production and use. Quantitative assessments are 

29 presented, where possible, however, in most cases only qualitative assessments were feasible due 

30 to uncertainties and the lack of data and analyses in the peer-reviewed literature. Conclusions, 

31 which do not account for existing or potential future mitigation measures or regulations, include:

32 • Life Cycle Assessment. Some segments of the biofuel life cycle result in 

33 greenhouse gas (GHG) emissions; however, as noted in EPA’s RFS2 Regulatory 

34 Impact Analysis, when the entire biofuel life cycle is considered, the EISA35 mandated revisions to the RFS2 program are expected to achieve a 138-million 

36 metric ton reduction in carbon dioxide-equivalent emissions by 2022 compared to 

37 continued reliance on petroleum-based fuels.

38 

39 • Water Quality. Ground and surface water quality can be impacted by erosion and 

40 runoff of fertilizers and pesticides when feedstocks, particularly row crops such as 

41 corn, are cultivated for biofuel; through pollutants in the wastewater discharged 

42 from biofuel production facilities; and from leaks and spills during fuel transport. 

43 
Executive Summary

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44 • Water Quantity. Effects of feedstock production on water availability vary 

45 greatly by feedstock, processes used to produce the feedstock, and location. 

46 Depending on location, the amount of water required to grow corn and soybean 

47 for biofuel can be far greater than that required to grow perennial grasses, woody 

48 biomass, and algae. Water used by biofuel production facilities is modest 

49 compared to that required to produce biofuel feedstocks, and impacts depend on 

50 the location of the facility in relation to water resources.

51 

52 • Soil Quality. Increased cultivation of biofuel feedstocks is likely to affect soil 

53 quality in various ways, depending on the feedstock. Some feedstocks may 

54 contribute to detrimental effects, including increased soil erosion, decreased soil 

55 organic matter content, increased soil GHG emissions, and increased nitrogen and 

56 phosphorus losses to ground and surface waters. Other feedstocks may contribute 

57 to advantageous effects such as increased soil carbon and reduced erosion. 

58 

59 • Air Quality. Air quality may be impacted by pollutants from feedstock 

60 production, such as farm equipment emissions and soil/dust particles made 

61 airborne during field tillage and fertilizer application; by emissions from 

62 combustion equipment used for energy production at biofuel production facilities; 

63 and by evaporative and tailpipe emissions from combustion in vehicles. 64 

65 • Ecosystem. Increased cultivation of feedstocks for biofuel could significantly 

66 affect biodiversity through habitat alteration when uncultivated land is put into 

67 production; from exposure of flora and fauna to pesticides; or through 

68 sedimentation and eutrophication in water bodies resulting from soil erosion and 

69 nutrient runoff, respectively. Invasiveness potential of cultivated feedstocks is 

70 also a concern, but varies by feedstock. 71 

72 • International. Increases in U.S. biofuel production and consumption volumes 

73 will affect many different countries as trade patterns and prices adjust in response 

74 to global supply and demand. This will result in land use change and effects on air 

75 quality, water quality, and biodiversity. Direct and indirect land use changes will 

76 likely occur across the globe as the U.S. and other biofuel feedstock-producing 

77 countries alter their agricultural sectors to allow for greater biofuel production. 

78 Many locations where biofuel production is growing, such as Indonesia, 

79 Malaysia, and Brazil, are also areas of high biodiversity value. Depending where 

80 biofuel feedstock production occurs, and to what extent the level of production 

81 increases with time, impacts to biodiversity could be significant.

 82 

83 Most activities, processes, and products associated with the biofuel supply chain are 

84 already regulated, subject to limitations, or mitigated through various approaches. To further 

85 address adverse impacts, EPA recommends:

86 • Developing and evaluating Environmental Life Cycle Assessments for biofuels.

87 

88 • Ensuring the success of current and future environmental biofuel research through 

89 improved cooperation and sustained support. 

90 
Executive Summary

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91 • Improving the ability of federal agencies (within their existing authorities) to 

92 develop and implement best management and conservation practices and policies 

93 that will avoid or mitigate negative environmental effects from biofuel production 

94 and use. 

95 

96 • Engaging the international scientific community in cooperative efforts to identify 

97 and implement sustainable biofuel practices that minimize environmental impact.

98 Because biofuel impacts cross many topics and Agency responsibilities, EPA likely will 

99 address these recommendations through continued and strengthened cooperation with federal 

100 agencies and international partners, including the U.S. Departments of Agriculture and Energy.

 101 
Table of Contents

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1 Table of Contents

 2 

3 Page 

4 EXECUTIVE SUMMARY ...................................................................................................................... I

5 1. INTRODUCTION ................................................................................................................. 1-1

6 2. BACKGROUND AND APPROACH ......................................................................................... 2-1

7 2.1 EISA and RFS2 Requirements for Biofuel Production and Use ......................... 2-1

8 2.2 Projected Fuel and Feedstock Use to Meet Required RFS2 Targets through 

9 2022...................................................................................................................... 2-2

10 2.3 Assessment of the Environmental and Resource Conservation Impacts of 

11 Biofuels ................................................................................................................ 2-4

12 2.3.1 Approach ................................................................................................ 2-4

13 2.3.2 Biofuel Supply Chain ............................................................................... 2-5

14 2.3.3 Feedstocks and Fuels Discussed in This Report ...................................... 2-5

15 2.3.4 Impacts Discussed in This Report............................................................ 2-6

16 2.4 Regulatory Authority Relevant to Biofuel Environmental Impacts .................... 2-9

17 3. ENVIRONMENTAL IMPACTS OF SPECIFIC FEEDSTOCKS ...................................................... 3-1

18 3.1 Introduction .......................................................................................................... 3-1

19 3.2 Row Crops (Corn, Corn Stover, Soybeans) ......................................................... 3-2

20 3.2.1 Introduction .............................................................................................. 3-2

21 3.2.1.1 Current and Projected Cultivation ......................................... 3-3

22 3.2.1.2 Overview of Environmental Impacts ..................................... 3-6

23 3.2.2 Water Quality ........................................................................................... 3-9

24 3.2.2.1 Nutrient Loading .................................................................. 3-10

25 3.2.2.2 Sediment .............................................................................. 3-15

26 3.2.2.3 Pesticides.............................................................................. 3-16

27 3.2.2.4 Pathogens and Biological Contaminants ............................. 3-17

28 3.2.3 Water Quantity ....................................................................................... 3-18

29 3.2.3.1 Water Use............................................................................. 3-18

30 3.2.3.2 Water Availability ................................................................ 3-19

31 3.2.4 Soil Quality ............................................................................................ 3-20

32 3.2.4.1 Soil Erosion .......................................................................... 3-20

33 3.2.4.2 Soil Organic Matter.............................................................. 3-21

34 3.2.5 Air Quality ............................................................................................. 3-22

35 3.2.5.1 Cultivation and Harvesting .................................................. 3-22

36 3.2.5.2 Fertilizers and Pesticides...................................................... 3-23

37 3.2.6 Ecosystem Impacts................................................................................. 3-23

38 3.2.6.1 Eutrophication, Erosion, and Biodiversity Loss .................. 3-23

39 3.2.6.2 Invasive Plants ..................................................................... 3-25

40 3.2.7 Assessment ............................................................................................. 3-25

41 3.2.7.1 Key Uncertainties and Unknowns ....................................... 3-26

42 3.3 Perennial Grasses ............................................................................................... 3-28
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43 3.3.1 Introduction ............................................................................................ 3-28

44 3.3.1.1 Current and Projected Cultivation ....................................... 3-30

45 3.3.1.2 Overview of Environmental Impacts ................................... 3-31

46 3.3.2 Water Quality ......................................................................................... 3-31

47 3.3.2.1 Nutrient Loading .................................................................. 3-32

48 3.3.2.2 Sediment .............................................................................. 3-32

49 3.3.2.3 Pesticides.............................................................................. 3-33

50 3.3.2.4 Pathogens and Biological Contaminants ............................. 3-33

51 3.3.3 Water Quantity ....................................................................................... 3-33

52 3.3.3.1 Water Use............................................................................. 3-33

53 3.3.3.2 Water Availability ................................................................ 3-34

54 3.3.4 Soil Quality ............................................................................................ 3-34

55 3.3.4.1 Soil Erosion .......................................................................... 3-34

56 3.3.4.2 Soil Organic Matter.............................................................. 3-34

57 3.3.5 Air Quality ............................................................................................. 3-35

58 3.3.6 Ecosystem Impacts................................................................................. 3-36

59 3.3.6.1 Biodiversity .......................................................................... 3-36

60 3.3.6.2 Invasive Plants ..................................................................... 3-36

61 3.3.7 Assessment ............................................................................................. 3-38

62 3.3.7.1 Key Uncertainties and Unknowns ....................................... 3-38

63 3.4 Woody Biomass ................................................................................................. 3-39

64 3.4.1 Introduction ............................................................................................ 3-39

65 3.4.1.1 Current and Projected Production Areas .............................. 3-40

66 3.4.1.2 Overview of Environmental Impacts ................................... 3-41

67 3.4.2 Water Quality ......................................................................................... 3-41

68 3.4.2.1 Nutrients ............................................................................... 3-42

69 3.4.2.2 Sediment .............................................................................. 3-43

70 3.4.2.3 Pesticides.............................................................................. 3-43

71 3.4.3 Water Quantity ....................................................................................... 3-43

72 3.4.3.1 Water Use............................................................................. 3-43

73 3.4.3.2 Water Availability ................................................................ 3-44

74 3.4.4 Soil Quality ............................................................................................ 3-44

75 3.4.4.1 Soil Erosion .......................................................................... 3-44

76 3.4.4.2 Soil Organic Matter.............................................................. 3-44

77 3.4.4.3 Soil Nutrients ....................................................................... 3-45

78 3.4.5 Air Quality ............................................................................................. 3-45

79 3.4.6 Ecosystem Impacts................................................................................. 3-46

80 3.4.6.1 Biodiversity .......................................................................... 3-46

81 3.4.6.2 Invasive Plants ..................................................................... 3-46

82 3.4.7 Assessment ............................................................................................. 3-47

83 3.4.7.1 Key Uncertainties and Unknowns ....................................... 3-47

84 3.5 Algae .................................................................................................................. 3-48

85 3.5.1 Introduction ............................................................................................ 3-48

86 3.5.1.1 Current and Projected Cultivation ....................................... 3-49
Table of Contents

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87 3.5.1.2 Overview of Environmental Impacts ................................... 3-49

88 3.5.2 Water Quality ......................................................................................... 3-49

89 3.5.3 Water Quantity ....................................................................................... 3-50

90 3.5.3.1 Water Use............................................................................. 3-50

91 3.5.3.2 Water Availability ................................................................ 3-50

92 3.5.4 Soil Quality ............................................................................................ 3-51

93 3.5.5 Air Quality ............................................................................................. 3-51

94 3.5.6 Ecosystem Impacts................................................................................. 3-51

95 3.5.6.1 Biodiversity .......................................................................... 3-51

96 3.5.6.2 Invasive Algae ..................................................................... 3-52

97 3.5.7 Assessment ............................................................................................. 3-52

98 3.5.7.1 Current and Future Impacts ................................................. 3-52

99 3.5.7.2 Key Uncertainties and Unknowns ....................................... 3-53

100 3.6 Waste-Based Feedstocks .................................................................................... 3-54

101 3.6.1 Introduction ............................................................................................ 3-54

102 3.6.2 Municipal Solid Waste ........................................................................... 3-54

103 3.6.3 Other Wastes .......................................................................................... 3-55

104 3.6.4 Environmental Impacts of Waste-Based Biofuel ................................... 3-55

105 3.7 Summary of Feedstock-Dependent Impacts on Specialized Habitats ............... 3-56

106 3.7.1 Forests .............................................................................................. 3-56

107 3.7.2 Grasslands .............................................................................................. 3-57

108 3.7.3 Impacts on Wetlands .............................................................................. 3-58

109 3.8 Genetically Engineered Feedstocks ................................................................... 3-59

110 4. BIOFUEL PRODUCTION, TRANSPORT, STORAGE AND END USE ......................................... 4-1

111 4.1 Introduction .......................................................................................................... 4-1

112 4.2 Feedstock Logistics .............................................................................................. 4-2

113 4.2.1 Handling, Storage, and Transport ............................................................ 4-2

114 4.2.1.1 Ethanol ................................................................................... 4-2

115 4.2.1.2 Biodiesel ................................................................................ 4-2

116 4.3 Biofuel Production ............................................................................................... 4-3

117 4.3.1 Biofuel Conversion Processes.................................................................. 4-3

118 4.3.1.1 Ethanol ................................................................................... 4-3

119 4.3.1.2 Biodiesel ................................................................................ 4-4

120 4.3.2 Air Quality ............................................................................................... 4-5

121 4.3.2.1 Ethanol ................................................................................... 4-7

122 4.3.2.2 Biodiesel ................................................................................ 4-7

123 4.3.2.3 Greenhouse Gases .................................................................. 4-7

124 4.3.3 Water Quality and Availability ................................................................ 4-9

125 4.3.3.1 Ethanol ................................................................................. 4-10

126 4.3.3.2 Distillers Grain with Solubles .............................................. 4-11

127 4.3.3.3 Biodiesel .............................................................................. 4-12

128 4.3.4 Impacts from Solid Waste Generation ................................................... 4-13

129 4.4 Biofuel Distribution ........................................................................................... 4-13
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130 4.4.1 Air Quality ............................................................................................. 4-13

131 4.4.1.1 Ethanol ................................................................................. 4-13

132 4.4.1.2 Biodiesel .............................................................................. 4-14

133 4.4.2 Water Quality ......................................................................................... 4-14

134 4.4.2.1 Ethanol ................................................................................. 4-15

135 4.4.2.2 Biodiesel .............................................................................. 4-16

136 4.5 Biofuel End Use ................................................................................................. 4-16

137 4.5.1 Air Quality ............................................................................................. 4-17

138 4.5.1.1 Ethanol ................................................................................. 4-17

139 4.5.1.2 Biodiesel .............................................................................. 4-17

140 5. INTERNATIONAL CONSIDERATIONS ................................................................................... 5-1

141 5.1 Introduction .......................................................................................................... 5-1

142 5.2 Import/Export Volumes ....................................................................................... 5-3

143 5.3 Environmental Impacts of Direct and Indirect Land Use Changes ..................... 5-6

144 5.4 Other Environmental Impacts ............................................................................ 5-10

145 5.5 Concluding Remarks .......................................................................................... 5-12

146 6. CONCLUSIONS AND RECOMMENDATIONS .......................................................................... 6-1

147 6.1 Conclusions .......................................................................................................... 6-1

148 6.1.1 Emissions Reduction ................................................................................ 6-1

149 6.1.2 Feedstock Production ............................................................................... 6-1

150 6.1.2.1 Overview ................................................................................ 6-1

151 6.1.2.2 Conclusions ............................................................................ 6-3

152 6.1.3 Biofuel Production, Transport, and Storage ............................................ 6-4

153 6.1.3.1 Overview ................................................................................ 6-4

154 6.1.3.2 Biofuel Transport and Storage ............................................... 6-7

155 6.1.4 Biofuel End Use ....................................................................................... 6-7

156 6.1.5 International Considerations .................................................................... 6-7

157 6.2 Recommendations ................................................................................................ 6-8

158 6.2.1 Comprehensive Environmental Assessment ............................................ 6-8

159 6.2.2 Coordinated Research .............................................................................. 6-8

160 6.2.3 Mitigation of Impacts from Feedstock Production .................................. 6-9

161 6.2.4 International Cooperation to Implement Sustainable Biofuel 

162 Practices ................................................................................................ 6-9

163 7. ASSESSING ENVIRONMENTAL IMPACTS FROM BIOFUELS: 2013 TO 2022........................... 7-1

164 7.1 Introduction .......................................................................................................... 7-1

165 7.2 Components of the 2013 Assessment .................................................................. 7-1

166 7.2.1 Life Cycle Assessments ........................................................................... 7-2

167 7.2.2 Environmental Risk Assessment.............................................................. 7-2

168 7.2.3 Human Health Assessment ...................................................................... 7-2

169 7.2.4 Conceptual Models .................................................................................. 7-3

170 7.2.5 Monitoring, Measures, and Indicators ..................................................... 7-3

171 7.2.6 Scenarios ................................................................................................ 7-6
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172 7.2.7 Other Components ................................................................................... 7-8

173 8. REFERENCES ..................................................................................................................... 8-1

 174 

175 Appendix A: GLOSSARY AND ACRONYMS ...................................................................... A-1 

 176 

177 Appendix B: SUMMARY OF SELECTED STATUTORY AUTHORITIES HAVING 

178 POTENTIAL IMPACT ON THE PRODUCTION 

179 AND USE OF BIOFUELS ..................................................................................B-1 

 180 

181 Appendix C: BASIS FOR FIGURES 6-1, 6-2, AND 7-3 .........................................................C-1 

 182 

183 Appendix D: CONCEPTUAL MODELS ................................................................................. D-1 

 184 

 185 
List of Tables

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186 LIST OF TABLES

 187 

188 Page 

 189 

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 Feedstocks ...................................................................................................................... 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
List of Figures

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217 LIST OF FIGURES

218 

219 Page 

 220 

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 (kgCO2e/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
List of Figures

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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

257 
Chapter 1: Introduction

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1 1. INTRODUCTION

2 In December 2007, Congress enacted the Energy Independence and Security Act (Public 

3 Law 110-140) (EISA) to reduce U.S. energy consumption and dependence on foreign oil, and to 

4 address climate change through research and implementation of strategies to reduce greenhouse 

5 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 6 to

increase the volume of renewable fuelb

9 EPA finalized revisions to the RFS program in February 2010. The revised statutory 

10 requirements (commonly known as the RFS2) establish new specific annual volume standards 

11 for cellulosic biofuel, biomass-based diesel, advanced biofuel, and total renewable fuel that must 

12 be used in transportation fuel (see Chapter 2). Meeting RFS2 in 2022 will result in biofuels 

13 making up an estimated 7 percent of fuels (by volume) used for transportation (U.S. EPA, 

14 2010a). The purpose of this report is to examine the environmental and resource conservation 

15 impacts of this change, as required under EISA Section 204. 

7 required to be blended into transportation fuel from 9 

8 billion gallons per year in 2008 to 36 billion gallons per year by 2022. 

16 EISA Section 204 calls for EPA to report to Congress every three years on the 

17 environmental and resource conservation impacts of increased biofuel production and use as

18 follows:

19 In General. Not later than 3 years after the enactment of this section and every 3 years

20 thereafter, the Administrator of the Environmental Protection Agency, in consultation with the 

21 Secretary of Agriculture and the Secretary of Energy, shall assess and report to Congress on the 

22 impacts to date and likely future impacts of the requirements of Section 211(o) of the Clean Air

Actc

1. Environmental issues, including air quality, effects on hypoxia, pesticides,

23 on the following: 

d

27 2. Resource conservation issues, including soil conservation, water availability, and 

28 ecosystem health and biodiversity, including impacts on forests, grasslands, and 

29 wetlands. 

24 

25 sediment, nutrient and pathogen levels in waters, acreage and function of waters, 

26 and soil environmental quality. 

30 3. The growth and use of cultivated invasive or noxious plants and their impacts on 

31 the environment and agriculture. 

32 4. .... The report shall include the annual volume of imported renewable fuels and 

33 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. c EISA 2007 amended Section 211(o) of the Clean Air Act to include the definitions and requirements of RFS2.

d Pesticides include antimicrobials, fungicides, herbicides, insecticides, and rodenticides.
Chapter 1: Introduction

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34 States of producing such fuels and feedstocks. The report required by this

35 subsection shall include recommendations for actions to address any adverse 

36 impacts found. 

 37 

38 This is the first of EPA’s triennial reports on the current and potential future

39 environmental impacts associated with the requirements of Section 211(o) of the Clean Air Act.

40 This report reviews environmental and resource conservation impacts, as well as mitigation tools 

41 to reduce these impacts, across major components of the biofuel supply chain: feedstock 

42 production, feedstock logistics, biofuel production, biofuel distribution, and biofuel use. 

43 This report emphasizes domestic impacts; however, the substantial market created for

44 biofuels by the U.S, Brazil, and other countries has important global implications. For example, 

45 countries that produce feedstocks, now or in the future, which are converted to biofuels that 

46 qualify for use in the U.S. will experience direct impacts; other countries will have to adapt to 

47 changing agricultural commodity distributions that result from diversion of food exports to 

48 biofuel production. As required under EISA Section 204, this report describes the impacts of 

49 increased feedstock and biofuel production in other countries as a result of U.S. policy. 

50 This first triennial Report to Congress represents the best available information through 

51 July 2010 and reflects the current understanding about biofuel production and use, including 

52 input from the U.S Departments of Agriculture and Energy, with whom EPA consulted during 

53 development of this report. Quantitative assessments are presented, where possible, using 2010 

54 or the most recently available data; however, in most cases only qualitative assessments were 

55 feasible due to uncertainties and lack of data and analyses in the peer-reviewed literature. Future 

56 reports will reflect the evolving understanding of biofuel impacts in light of new research results 

57 and data as they become available. This initial report to Congress serves as a starting point for

58 future assessments and for taking action to achieve the goals of EISA. 

 59 
Chapter 2: Background and Approach

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1 2. BACKGROUND AND APPROACH

2.1

3 RFS2 (the Renewable Fuel Standard as amended by the Energy Independence and 

4 Security Act [EISA]) establishes new specific annual volume standards for four categories of 

renewable fuels that must be used in transportation fuel

2 EISA and RFS2 Requirements for Biofuel Production and Use

5 5 : cellulosic biofuel, biomass-based 

6 diesel, advanced biofuel, and total renewable fuel (see Glossary in Appendix A for fuel 

7 definitions). Under RFS2, conventional biofuel (i.e., ethanol derived from corn starch) with a 

maximum volume target and “additional renewable fuels”6 8 are included as eligible fuels to meet 

9 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

14 Table 2-1 shows the RFS2 annual renewable fuel standards through 2022. Total 

15 renewable fuel under the standard will increase to 36 billion gallons per year (bgy) by 2022 (of 

16 which corn starch ethanol is not to exceed 15 bgy). 

10 including new 

11 greenhouse gas emission (GHG) reduction thresholds (as determined by the life cycle assessment

12 that EPA conducted as part of its Regulatory Impact Analysis [RIA] during the final RFS2 

13 rulemaking). 

17 While EISA establishes the renewable fuel volumes shown in Table 2-1, it also requires 

18 the EPA Administrator each November to set the volume standards for the following year based 

19 in part on information provided by the Energy Information Administration (EIA) and other data 

20 indicating the commercial capacity for producing cellulosic biofuels. EISA therefore requires the 

21 EPA Administrator to adjust the cellulosic standard, and potentially the total advanced biofuel 

22 and total renewable fuel standards, each year based on this assessment. For 2010, the 

23 Administrator adjusted the cellulosic standard from 0.1 bgy (100 million gallons per year) in 

24 RFS2 to 5.0 million gallons, but did not adjust the total advanced or total renewable fuel 

standard.8

 

5 Transportation fuel includes fuels used in motor vehicles, motor vehicle engines, non-road vehicles, or non-road

engines (except for ocean-going vessels). 

25 Therefore, the final 2010 standard for total renewable fuel is set at 12.95 bgy, with 

26 specific targets for cellulosic biofuel (5.0 million gallons per year), biomass-based diesel (1.15 

27 bgy [combining the 2009 and 2010 standards as proscribed in RFS2]), and total advanced biofuel 

28 (0.95 bgy). 

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 II.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.
Chapter 2: Background and Approach

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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

Cellulosic Biofuel Renewable Fuel

Biomass-Based

Diesel Advanced Biofuel c

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

29 a – The requirements for cellulosic biofuel, biomass-based diesel, advanced biofuel, and total renewable fuel are 

30 minimum required volumes that must be achieved and may be exceeded. The conventional biofuel requirement is a 

31 cap that cannot be exceeded.

32 b – Note that the RFS2 volume requirements are nested: cellulosic biofuel and biomass-based diesel are forms of 

33 advanced biofuel; and advanced biofuel and conventional biofuel are forms of total renewable fuel.

34 c – Note that the sum of the required amounts of cellulosic biofuel and biomass-based diesel is less than the required 

35 volume of advanced biofuel. The additional volume to meet the advanced fuel requirement may be achieved by the 

36 additional cellulosic biofuel and biomass-based diesel (i.e., beyond the required minimum) and/or by other fuels that 

37 meet the definition of advanced biofuel (e.g., sugarcane ethanol).

38 d – As described above, and as allowed under EISA, the EPA Administrator determined that original RFS2 standard

39 of 0.1 bgy for cellulosic biofuel was not achievable for 2010 and therefore decreased this standard to 5 million

40 gallons for 2010. 

41 e – To be determined by EPA through a future rulemaking, but no less than 1.0 billion gallons. This requirement was 

42 designated under EISA as “to be determined” with a minimum requirement because of the uncertainty about future 

43 capacity to produce fuel that meets the biomass-based diesel definition.

44 Source: U.S. EPA, 2010b.

 45 

2.2

47 Figure 2-1 summarizes the fuel types and volumes projected to meet the required targets 

48 through 2022, as estimated in the RFS2 Regulatory Impact Analysis. Although actual volumes 

49 and feedstocks will likely be different, EPA believes the projections are within the range of 

50 expected outcomes when the standards are met (U.S. EPA, 2010b). 

46 Projected Fuel and Feedstock Use to Meet Required RFS2 Targets through 2022
Chapter 2: Background and Approach

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51 

52 Source: U.S. EPA, 2010b.

53 Figure 2-1: Projected Renewable Fuel Volumes to Meet RFS2 Targets

54 In 2009, corn ethanol constituted 95 percent of total U.S.-produced renewable fuel, with 

55 biodiesel made from soybean oil, other virgin vegetable oils, rendered fats, greases, and corn oil 

56 from ethanol production accounting for almost all the remaining biofuel consumed (FAPRI, 

57 2010a; EIA, 2010). However, as technologies improve, EPA expects more advanced cellulosic

58 feedstocks, such as agricultural residues (e.g., corn stover, sugarcane bagasse, wheat residue, 

59 sweet sorghum pulp), forestry biomass, urban biomass waste, and dedicated energy crops (e.g., 

60 switchgrass) to produce biofuels (Figure 2-2) (U.S. EPA, 2010b). Present research is focused on 

61 improving technologies to convert different feedstocks to biofuels in an economically viable 

62 manner, and determining sustainable biofuel production methods. 
Chapter 2: Background and Approach

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63 

64 Figure 2-2: Examples of Feedstocks Available for Biofuel Production 

65 With respect to biodiesel, EPA expects continued use of soybean oil, which made up 54 

66 percent of feedstock used for biodiesel in 2009 (EIA, 2010), as well as a varying percentage of 

67 other vegetable oils, rendered fats, greases, and corn oil from ethanol production through 2022 

68 (see Table 4-1 for a more detailed breakdown) (U.S. EPA, 2010b). Algae could potentially 

69 provide large volumes of oil for the production of biomass-based diesel. However, several 

70 hurdles, including technical issues, will likely limit production volumes within the 2022 

71 timeframe (U.S. EPA, 2010b). 

72 Imported sugarcane ethanol, also represents a significant potential supply of biofuel by 

73 2022 (U.S. EPA, 2010b). In 2009, the United States imported 198 million gallons of ethanol 

74 (EIA, n.d. [d]). Import volumes are expected to grow as U.S. demand increases to meet the 

75 biofuel targets.

2.3

77 2.3.1 Approach 

76 Assessment of the Environmental and Resource Conservation Impacts of Biofuels

78 This report presents a comprehensive survey of environmental evaluations across the 

79 biofuel supply chain (see below), including current and anticipated future feedstock production 

80 and logistics and biofuel production, distribution, and use. It summarizes much of the available

81 information and identifies research needed to evaluate potential environmental impacts from a 

82 life cycle perspective and quantify them using more substantive and systematic assessment tools. 

83 This report therefore is the first step towards conducting a biofuels environmental life cycle

84 assessment (LCA), which EPA will conduct for its future Reports to Congress (see Chapter 7). 

85 Life cycle assessment evaluates environmental impacts resulting from all stages of a 

86 product’s development—from extraction of fuel for power to production, marketing, use, and
Chapter 2: Background and Approach

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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 biofuels 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.

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.
Chapter 2: Background and Approach

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* 

** 

* 

120 2.3.4 Impacts Discussed in This Report 

121 This report focuses on specific environmental and resource conservation impacts

122 specified in EISA Section 204, as shown in Figure 2-4 and described in Tables 2-2 and 2-3. This 

123 report does not include extensive discussion of carbon dioxide or other greenhouse gas

124 emissions; interested readers are referred to the EPA’s RFS2 Regulatory Impact Analysis (U.S. 

125 EPA, 2010b). A short discussion is provided in Section 4.3.2.3 of this report. The environmental 

126 and resource conservation impacts discussed in this report reflect a complex set of interactions

127 and feedbacks between land, soil, air, and water; future versions of this report will explore 

128 analysis of these important complexities as enhanced data and analysis tools become available.

129 This report does not attempt to conduct a quantitative analysis of the range of impacts associated 

130 with increased production of biofuel. Instead, it represents a compilation of available information 

131 and analyses that can inform the nature and extent of impacts that might be expected to occur. 

132 Thus, this report does not use a baseline year, per se, against which future impacts can be 

133 measured. Different impacts have been assessed using applicable baselines cited in the literature 

134 or, as appropriate, in the RFS2 RIA. Generally, however, the primary reference point used in this 

135 document is consistent with the primary reference case used in the RFS2 RIA. This reference 

136 case is a projection made by the U.S. Energy Information Administration prior to EISA in their 

137 2007 Annual Energy Outlook of renewable fuel volumes expected in 2022. 

138 

139 * Includes pesticides, sediments, nutrients, pathogens, and acreage/function of wetlands

140 ** Includes invasive/noxious plants, forests, grasslands, wetlands, and aquatic ecosystems

141 Figure 2-4: Environmental and Resource Conservation Issues Addressed in This Report
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142 Chapter 3 focuses on feedstock production, including cultivation and harvest. Chapter 4 

143 covers impacts of feedstock logistics and biofuel production, distribution, and use. Many

144 activities, processes, and products associated with the biofuel supply chain are already regulated, 

145 are subject to limitations, or are mitigated through various approaches, as discussed in these 

146 chapters. The potential impacts associated with imported biofuels are discussed in Chapter 5. 

147 Currently, imported ethanol and biodiesel supply a relatively small percentage of U.S. biofuel 

148 consumption—approximately 9 percent in 2008 (EIA, 2009, n.d.[a]; U.S. ITC, 2010; ERS, 

149 2010a). If these percentages increase, future versions of this report may provide expanded 

150 analysis of international impacts associated with imported biofuels. 

151 EPA’s ability to assess environmental and resource conservation impacts is limited by

152 uncertainties associated with even a qualitative assessment of the direct impacts. Many feedstock

153 technologies are in the early stages of research and development, therefore empirical and

154 monitoring data relevant to environmental impacts are limited and projections of their potential 

155 future use are highly speculative. Recommendations in Chapter 6 and the approach to future 

156 assessments described in Chapter 7 address how the EPA intends to bolster data availability and

157 analysis to improve understanding of environmental impacts in future reports. 

Table 2-2: Overview of Environmental and Resource Conservation Impacts

Addressed in This Report a

Feedstock Production and 

Transportation Fuel Production, Distribution, and Use

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
Chapter 2: Background and Approach

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Table 2-2: Overview of Environmental and Resource Conservation Impacts

Addressed in This Report a

Feedstock Production and 

Transportation Fuel Production, Distribution, and Use

Ecosystem

Health/Biodiversity

(including invasive

and noxious plants)

• Impacts on flora and fauna and loss of 

ecosystem services due to pollution and 

habitat changes

• Establishment and spread of invasive or

noxious plants

• Establishment and spread of invasive 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 Report a

Feedstock 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.
Chapter 2: Background and Approach

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Table 2-3: Overview of Environmental and Resource Conservation Impacts on Specific 

Ecosystems Addressed in This Report a

Feedstock 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.

161 a – The impacts in this table are generalized and do not take into account location or effectiveness of mitigation 

162 practices. 

 163 

2.4

165 EPA, as well as states, tribes, and local environmental agencies, has statutory 

166 responsibility to assess and control air emissions, water discharges, use of toxic substances,

167 microbial and pesticide use, and waste disposal. Many existing environmental regulations and

168 programs are applicable to the biofuel supply chain, including feedstock production and

169 logistics; biofuel production and distribution, and biofuel use. 

164 Regulatory Authority Relevant to Biofuel Environmental Impacts

170 EPA’s primary federal regulatory authority is derived from the Clean Air Act (CAA); the 

171 Clean Water Act (CWA), the Federal Insecticide Fungicide and Rodenticide Act (FIFRA); 

172 Resource Conservation and Recovery Act (RCRA) and the Toxic Substances Control Act 

173 (TSCA). Under the CAA, EPA has broad direct statutory authority to regulate fuel quality and

174 emissions from refining and production facilities for all fuels, including biofuels. The CAA also 

175 establishes limits for mobile source (vehicular) emissions. The Clean Water Act requires permits 

176 for point source discharges to waters of the U.S, and development of water quality standards, and 

177 Total Maximum Daily Loads (TMDLs) for water bodies where water quality standards have not 

178 been met. FIFRA establishes standards for storage and use of pesticides in a manner that does 

179 not harm human health or the environment. RCRA governs the generation, storage, treatment, 

180 transport, and disposal of hazardous waste. TSCA requires manufacturers and importers of new 

181 chemicals to submit “pre-manufacture” notices for EPA review prior to manufacture and

182 commercial use of new chemicals, including new fuels, new biological materials, and new 

183 genetically engineered microorganisms used to produce biofuels or co-products. Through the 

184 CWA’s Spill Prevention, Control and Countermeasure rule, EPA has enforceable regulations to

185 control water quality impacts from spills or leaks of biofuel products and by-products. In 

186 addition, the Safe Drinking Water Act establishes maximum contaminant levels (MCLs) for 

187 more than 90 drinking water contaminants to ensure public health. These statutes provide 

188 opportunities within the existing regulatory framework to regulate and mitigate some of the 

189 potential adverse health and environmental effects of biofuels. Selected environmental laws 

190 relevant to the production and use of biofuels are summarized in Appendix B.
Chapter 2: Background and Approach

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191 Generally, EPA headquarters offices develop policies and regulations for these federal

192 statutes, while regional EPA offices, in partnership with the states and tribes, implement these

193 programs, ensure compliance, and enforce regulations. EPA and its regional offices work closely

194 with states and tribes to review permit applications for new facilities and to monitor 

195 environmental impacts to ensure compliance with all permit conditions. EPA has prepared two 

196 documents to help biofuel facilities understand the full range of regulatory requirements (U.S. 

197 EPA, 2007a, 2008a). While EPA has oversight authority for federal environmental regulatory 

198 programs and regulations, state agencies and tribes are often “delegated” the responsibility for

199 issuing permits, conducting inspections, ensuring compliance, and taking enforcement action. 

200 EPA regulations establish minimum requirements. States can enact more stringent standards, 

201 although several states have enacted legislation that prohibits adopting requirements stronger 

202 than those set by EPA. 
Chapter 3: Environmental Impacts of Specific Feedstocks 

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1 3. ENVIRONMENTAL IMPACTS OF SPECIFIC FEEDSTOCKS

3.1

3 The Energy Independence and Security Act (EISA) requires that all renewable fuel be 

4 made from feedstocks that meet the definition of renewable biomass (see textbox). Many 

5 different feedstocks meet these requirements and can be used to produce ethanol, other biofuels 

6 or biofuel components. 

2 Introduction

7 In 2009, 95 percent—or 10.9 billion gallons—of total renewable fuel produced in the 

8 U.S. was produced from corn and refined almost entirely in the form of conventional corn starch 

9 ethanol (FAPRI, 2010a). Soybean oil-based biodiesel accounted for most of the remainder—505 

10 million gallons. EPA expects that corn and soybean feedstocks will continue to account for a 

11 large share of biofuel production in the U.S. (U.S. EPA, 2010b) in the near future. As of July 

12 2010, there was no significant commercial-scale production of ethanol from cellulosic or 

13 hemicellulosic feedstocks, nor was there significant biodiesel production from oil seed 

14 feedstocks other than soybean in the U.S. 

15 As science and technology improves, 

16 EPA expects an increase in the use of 

17 cellulosic feedstocks to produce advanced 

18 biofuel. Such feedstocks include agricultural 

19 residues (e.g., corn stover, sugarcane 

20 bagasse, sweet sorghum pulp), forestry 

21 biomass, urban waste, and dedicated energy 

22 crops (e.g., switchgrass) (U.S. EPA, 2010b). 

23 Technologies for producing biodiesel from 

24 vegetable oils, recycled oils, rendered fats, 

25 greases, and algal oils have been developed 

26 and tested at various scales from the 

27 laboratory to demonstration plants and semi28 commercial facilities. EPA expects biodiesel 

29 from these feedstocks to gain a wider market 

30 share as their production becomes more 

31 economically and technologically feasible 

32 (U.S. EPA, 2010b). 

33 The feedstocks discussed in this 

34 chapter include corn and soybeans, as well 

35 as four others currently under development: 

36 corn stover, perennial grasses, woody 

37 biomass, and algae (see Table 3-1). These 

38 feedstocks represent different cultivation 

39 and production practices. 

40 This chapter reviews the actual (where known) and potential environmental impacts of 

41 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 nonfederal 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 (USDA) data on lands in agricultural 

production to determine if these conclusions remain 

valid.
Chapter 3: Environmental Impacts of Specific Feedstocks 

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42 quality, and ecosystem health/biodiversity. Feedstock production impacts are considered during 

43 the cultivation and harvest processes (see Figure 2-3). Impacts associated with the subsequent 

44 four stages of the biofuel supply chain are presented in Chapter 4. Row crop feedstocks (corn, 

45 corn stover, and soybean), which share many commonalities, are discussed in Section 3.2. 

46 Sections 3.3 to 3.5 present potential effects associated with switchgrass, woody biomass, and 

47 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

 48 

49 In addition to the six primary feedstocks examined in this report, Section 3.6 briefly 

50 discusses waste materials as potential emerging feedstocks for biofuels. In addition to general 

51 ecosystem impacts, Section 3.7 reviews impacts on specialized habitats (forests, grasslands, and 

52 wetlands), as required under EISA Section 204. Section 3.8 reviews environmental concerns 

53 associated with genetic engineering of feedstocks, commonly referred to as genetically modified 

54 organisms (GMOs).

3.2

56 3.2.1 Introduction

55 Row Crops (Corn, Corn Stover, Soybeans)

57 U.S. corn and soybean production 

58 have increased steadily over the past 

59 several decades. Increased demand for 

60 biofuel provides additional incentive to 

61 continue research and development for

62 increasing crop yields. As shown in Figure 

63 3-1, U.S. corn production increased by 

64 more than a factor of four between 1950 

65 and 2010. These increases were largely 

66 due to gains in efficiency and crop yield. 

67 Soybean yields have also increased. For 

68 example, soybean yields increased from 

69 21.7 bushels per acre in 1950 to 43.9 

70 bushels per acre in 2010 (NASS, 2010a). 

Source: NASS, 2010a.

Figure 3-1: U.S. Corn Production 
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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

In 20099

85 

75 , 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. 

86 Source: NASS, 2010b.

87 Figure 3-2: Planted Corn Acres by County, for Selected States (2009) 

 88 

 

9 As of January 2011, 2009 was the last year for which USDA NASS and EIA had complete datasets.
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89 EISA establishes 15 billion gallons as the maximum amount of corn starch ethanol that 

90 can contribute to meeting the 36 billion gallon per year renewable fuel target in 2022. Domestic 

91 production, which totaled 10.9 billion gallons in 2009 (EIA, n.d.[c]), is expected to meet this 

92 target through a combination of increased corn yield, increased acreage, and, potentially, 

93 improved efficiency in converting corn starch to ethanol. U.S. Department of Agriculture 

94 (USDA) estimates that planted corn acreage will remain at 88 million acres through 2021(USDA 

95 does not project acreage beyond 10 years), as U.S. demand for biofuel increases (USDA, 2010a). 

96 In the RFS2 analysis, EPA estimates that in order to produce 15 billion gallons of corn starch 

97 ethanol per year by 2022, the percentage of corn acreage dedicated to ethanol could rise from the 

98 current 38 percent to as high as 41 percent in 2022 (U.S. EPA, 2010b). 

99 Concern has been raised that the demand for corn ethanol may put pressure on the 

100 USDA’s Conservation Reserve Program (CRP) (Secchi and Babcock, 2007). This program 

101 provides farmers with financial incentives to set aside a certain portion of their cropland for 

102 buffer zones in order to conserve wildlife habitat, reduce erosion, protect water quality, and 

103 support other environmental goals. CRP lands are not precluded by the feedstock requirements 

104 for renewable fuels (see text box on page 3-1) from being used to grow biofuel feedstocks. 

105 Therefore their conversion to biofuel feedstocks could reduce the effectiveness of the CRP 

106 program in protecting the environment, and could result in increased environmental impacts, 

107 depending on the nature (i.e., crop) and extent of the conversion. One estimate, which examined 

108 the state of Iowa, predicted that high corn prices could lead to the recultivation of up to 70 

109 percent of the expiring acreage enrolled in the CRP (Secchi and Babcock, 2007). Other states 

110 may not have such high rates of recultivation given that much of the land in the CRP is marginal 

111 and would be expensive to cultivate. 

112 The Food, Conservation, and Energy Act of 2008 (Farm Bill) capped CRP acreage at 32 

113 million, reducing enrollment by 7.2 million acres from the 2002 Farm Bill and potentially 

114 making more acreage available for corn production (ERS, 2008). In 2007, approximately 28.5 

115 million acres or 78 percent of all CRP lands consisted of some type of grassland (FSA, 2008). 

116 A USDA study estimates that, to meet the renewable fuel standard, total cropland will 

117 increase 1.6 percent over 2008 baseline conditions by 2015, with corn acreage expanding 3.5 

118 percent, accounting for most of the cropland increase (Malcolm et al., 2009). While corn acreage 

119 is expected to expand in every region, this USDA study estimates that traditional corn-growing 

120 areas would likely see the largest increases—up 8.6 percent in the Northern Plains, 1.7 percent in 

121 the Corn Belt, and 2.8 percent in Great Lakes States (Malcolm et al., 2009). Historically, corn 

122 has been grown in rotation with other crops such as wheat, hay, oats, and especially soybeans. 

123 However, high corn prices have created incentives for continuous cultivation of corn (NASS, 

124 2007a), and in some cases conversion of non-cropland to corn. 

125 Corn stover—the stalks, leaves, husks, and cobs that are not removed from the fields 

126 when the corn grain is harvested—provides another potential feedstock for meeting EISA 

127 requirements. In the RFS2 RIA, EPA estimated that 7.8 billion gallons of ethanol could be 

128 produced from corn stover by 2022. Most corn stover harvesting for biofuel is expected to be 

129 from the major corn producing states. As of July 2010, there is no commercial production of 

130 cellulosic ethanol from corn stover. 
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131 Because corn stover protects underlying soil from wind and water erosion, the use of corn 

132 stover as a feedstock could increase soil erosion and environmental impacts compared to existing 

133 practices (Sheehan et al., 2004; Williams et al., 2009). The USDA’s Natural Resource 

134 Conservation Service (NRCS) has established soil loss tolerance levels, and farmers harvesting 

135 corn stover are encouraged to maintain a minimum level of groundcover or using other practices 

136 to minimize soil loss. Under current rotation and tillage practices, approximately 30 to 40 percent 

137 of stover could be collected cost effectively, taking into consideration erosion reduction, soil 

138 moisture needs and nutrient replacement (Graham et al., 2007; Perlack et al., 2005). 

139 Maintaining soil carbon levels is another concern that should be taken into account when 

140 determining the extent of stover harvesting. To maintain soil carbon levels, a significant portion 

141 of the corn stover would need to be left on fields, reducing the amount of the biomass that could 

142 be collected for feedstock. Sustainable residue removal rates depend on tillage practices, with no143 till allowing for the greatest level of sustainable removal. Developing a single national estimate 

144 of the amount of residue that must remain on the ground to meet conservation goals is difficult 

145 because much depends on site-specific conditions. 

146 After corn, soybean is the second largest agricultural crop (in terms of acreage) in the 

147 U.S. In 2009, American farmers planted 77.4 million acres and harvested 3.4 billion bushels. In 

148 2010, American farmers planted 77.7 million acres of soybeans and again harvested 3.4 billion 

149 bushels (NASS, 2010a). Soybean oil is the principal oil used for commercial production of 

150 biodiesel in the U.S., responsible for about half of total biodiesel production, with the rest 

151 coming from various other vegetable oils such as canola oil as well as waste fats, tallow and 

152 greases (see Table 4-1 for more detailed breakdown) (EIA, 2010). In harvest year 2008/2009, 

153 approximately 5.6 percent of the soybean harvest, or about 1.9 billion pounds of soybean oil 

154 (USDA, 2010b), went to biodiesel production and yielded 505 million gallons in calendar year 

155 2009 (EIA, n.d. [d]). This was a significant decline from the production total in 2008 of 676 

156 million gallons (EIA, n.d. [d]). Nonetheless, USDA expects the percentage of soybean harvest 

157 going to biodiesel to increase to 7.8 percent by 2012 and holding steady through 2019. USDA 

158 also projects that soybean oil used for biodiesel will represent 13-15 percent of total use of 

159 soybean oil–approximately 400 million gallons of biodiesel (USDA, 2010b).10 USDA estimates 

160 that soybean acreage will level off at approximately 76 million acres through 2019 (USDA, 

161 2010b). 

162 In terms of cultivation, soybeans are typically grown in the same locations as corn. Figure 

163 3-3 shows that soybean production is centered in the Upper Midwest and along the Mississippi 

164 River Valley, with Iowa, Illinois, Indiana, Minnesota, and Nebraska representing the top 

165 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. 
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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 
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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) 

Impact/Resource 

Use Category Corn Starch a Harvest of Corn Stover Soybean

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. 
Chapter 3: Environmental Impacts of Specific Feedstocks 

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Table 3-2: Impacts Associated with Biofuel Feedstock Production 

(Corn Starch, Corn Stover, and Soybean) 

Impact/Resource 

Use Category Corn Starch a Harvest of Corn Stover Soybean

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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Table 3-2: Impacts Associated with Biofuel Feedstock Production 

(Corn Starch, Corn Stover, and Soybean) 

Impact/Resource 

Use Category Corn Starch a Harvest of Corn Stover Soybean

Invasiveness 

Potential

Corn is non-invasive. See “Corn” Soybean is non-invasive. 

194 a – Impacts associated with corn production are described in the “Corn Starch” column. 

 195 

196 Cultivation of row crops such as corn and soybeans may lead to high levels of soil 

197 erosion, nutrient loss, and pesticide and water use if not managed adequately (Groom et al., 

198 2008, Table 1). Agricultural conservation systems may be used to reduce or minimize the impact 

199 of row crop agriculture on the environment. The systems support 1) controlled application of 

200 nutrients and pesticides through proper rate, timing, and method of application, 2) controlling 

201 erosion in the field (i.e., reduced tillage, terraces, or grassed waterways), and 3) trapping losses 

202 of soil at the edge of fields or in fields through practices such as cover crops, riparian buffers, 

203 controlled drainage for tile drains, and constructed/restored wetlands (Blanco-Canqui et al., 

204 2004; Dinnes et al., 2002; NRCS, 2010). 

205 The effectiveness of conservation practices, however, depends upon their adoption. The 

206 USDA Conservation Effects Assessment Project (CEAP) recently released a major study 

207 quantifying the effects of conservation practices commonly used on cultivated cropland in the 

208 Upper Mississippi River Basin. It found that, while erosion control practices are commonly used, 

209 there is considerably less adoption of proper nutrient management techniques to mitigate 

210 nitrogen loss to water bodies (NRCS, 2010). 

211 Further, even when erosion practices are reliably implemented, conservation practices 

212 and best management practices (BMPs) are not a panacea. A case study in the Chesapeake Bay

213 (CENR, 2010) found that, although the implementation of BMPs since 2000 has significantly 

214 lowered loadings of nitrogen (72 percent of sites showed downward trends), total phosphorus (81 

215 percent of sites), and sediment (43 percent of sites), lower nutrient input has not improved 

216 dissolved oxygen levels overall in the Chesapeake Bay, with the exception of small-scale 

217 reversals in hypoxia.

218 3.2.2 Water Quality

219 Water quality impacts from increased corn and soybean production for biofuel may be 

220 significant, and are caused by pollution from nutrients, sediment, and pesticides, as well as 

221 biological contaminants such as pathogens that are released when animal manure is applied as 

222 fertilizer. Multiple studies predict that increased production of crops for biofuels will exacerbate 

223 water quality problems in the Gulf of Mexico and other U.S. coastal waters if the crops are not 

224 grown under improved agricultural conservation practices and expanded nutrient BMPs (Greene 

225 et al., 2009, and Rabalais et al., 2009, cited in CENR, 2010). 
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226 3.2.2.1 Nutrient Loading 

227 Nutrients—Surface Water Impacts 

228 Increased production of row crops for biofuel, especially corn, will increase nitrogen and 

229 phosphorus loading to surface waters if not managed appropriately. Excessive levels of nutrients 

230 in a body of water can cause accelerated algal growth, reducing light penetration and oxygen 

231 levels. Low dissolved oxygen (i.e., hypoxia) can kill fish, reducing their populations and the 

232 species diversity in the affected area. This nutrient enrichment process (eutrophication) can cause 

233 serious deterioration of both coastal and inland water resources. According to a 2008 report by 

234 the National Research Council, excess nutrients and sediment from the high corn-producing 

235 Midwest are the primary sources of water quality degradation in the Mississippi River Basin and 

236 the Gulf of Mexico (NRC, 2008, p. 88). Further, the National Summary of Impaired Waters

(U.S. EPA, 2010c)11

251 In evaluating the potential for water quality impacts due to increased nutrient loads to 

252 surface waters, there is some debate about which nitrogen compounds to consider. Not all 

253 nitrogen compounds can be easily used by algae (i.e., are bioavailable) and thus some forms of 

254 nitrogen impact eutrophication more than others. Ammonia is the inorganic nitrogen compound 

255 that is easiest for most algae to use, followed by nitrate and nitrite (Cole, 1983). Total nitrogen is 

256 a measure of the sum of the nitrogen present in both inorganic and organic compounds in water. 

237 documented that in 2008, nationwide, approximately 50 percent of the 3.5 

238 million miles of stream and rivers and 66 percent of the over 41 million acres of lakes and 

239 reservoirs in the U.S. were impaired due to nutrient enrichment. The 2007 National Estuarine 

240 Eutrophication Assessment found that the Mid-Atlantic is the region most impacted by hypoxia, 

241 with almost 60 percent of the waters affected by anthropogenic land-based sources of nutrient 

242 pollution, agriculture being the largest contributor (CENR, 2010). The National Summary of 

243 Impaired Waters also reported that in 2008 over 68,000 miles of streams and rivers and over 1.3 

244 million acres of lakes and reservoirs in the Mississippi River Basin states were impaired because 

245 of nutrients. Increased corn and soybean production for biofuels could exacerbate this situation 

246 due to the nutrients from additional fertilizer or increases in the acreage or extent and density of 

247 subsurface tile drainage. The Committee on Environment and Natural Resources cites a 2008 

248 report that predicts the average annual flux of dissolved inorganic nitrogen to the Gulf of Mexico

249 could increase by 10 to 34 percent, based on a “pessimistic” scenario in which corn production 

250 acreage increases by up to 9 percent (Donner and Kucharik, 2008, cited in CENR, 2010). 

257 Although many studies track total nitrogen, some researchers argue that it is more 

258 appropriate to consider inorganic nitrogen compounds only, as those are most likely to impact 

259 water quality through eutrophication. When tracking the fate and transport of nitrogen in surface 

260 waters within large watersheds (e.g., in the Mississippi River Basin), it is important to remember 

261 that inorganic nitrogen compounds are readily converted to organic nitrogen compounds and 

262 back to inorganic compounds by organisms present in surface waters and sediments. At the basin 

263 scale, measuring total nitrogen provides insight into the potential maximum impact of nitrogen 

264 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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265 Corn has the highest fertilizer use per acre of any of the biofuel feedstocks, and it 

266 accounts for the largest portion of nitrogen fertilizer use among all feedstocks discussed in this 

267 report (U.S. EPA, 2010b). By one estimate, which surveyed 19 U.S. states, approximately 96 

268 percent of corn acreage received nitrogen fertilizer in 2005, with an average of 138 pounds per 

269 acre (NASS, 2006). An Iowa State University study found that each acre of harvested corn also 

270 requires about 55 pounds of phosphorus (in the form P2O5) (Iowa State University, 2008). 

271 Assuming a yield of 154 bushels per acre (NASS, 2010c) and an ethanol conversion rate of 2.7 

272 gallons per bushel (Baker and Zahniser, 2006), this results in 0.33 pounds of nitrogen and 0.13 

273 pounds of phosphorus applied per gallon of ethanol produced. Nitrogen discharged from corn 

274 fields via runoff, sediment transport, tile/ditch drainage, and subsurface flow averages 24 to 36 

275 percent of the nitrogen applied (and can range from 5 percent in drought years to 80 percent in 

276 flood years) (Dominguez-Faus et al., 2009). 

277 Nutrients are applied to fewer soybean acres compared to corn and at much lower rates 

278 (U.S. EPA, 2010b). However, losses of nitrogen and phosphorus from soybeans can occur at 

279 quantities that can degrade water quality (Dinnes et al., 2002; Randall et al., 1997). In 2006, the 

280 USDA’s National Agricultural Statistics Service estimated that nitrogen and phosphorus 

281 fertilizers were applied to 18 percent and 23 percent of soybean acreage, respectively, with an 

282 average of 16 pounds of nitrogen and 46 pounds of phosphate applied per acre fertilized (NASS, 

283 2007b). The quantity of nitrogen fertilizer applied to soybean fields ranged from 0 to 20 pounds 

284 per acre, while the quantity of phosphate ranged from 0 to 80 pounds per acre. Similar to corn, 

285 the conversion of idled acreage to soybeans is estimated to result in losses of nitrogen and 

286 phosphorus from the soil (Simpson et al., 2008). 

287 Corn requires less fertilizer when grown in rotation with soybeans. Therefore, crop 

288 rotation provides an effective strategy for reducing the amount of fertilizer and pesticide applied 

289 to fields, and therefore runoff and leaching of the pollutants to water. One study estimated that 2 

290 to 40 percent of the total nitrogen leached from fields planted alternately with corn and soybeans 

291 came from the fields when they were planted with soybeans, meaning that most of the nitrogen 

292 runoff was due to corn production (Powers, 2005). 

293 While the total amount of nitrogen lost from corn fields tends to be higher than losses 

294 from soybean fields (Powers, 2005), loss of inorganic nitrogen from corn and soybean fields 

295 tends to be similar. This suggests that eutrophic effects of nitrogen will be similar for runoff 

296 from both corn and soybean fields in surface waters near the fields. However, when considering 

297 impacts at the basin scale, it is more relevant to consider the total amount of nitrogen contributed 

298 by each crop.

299 Use of corn stover for ethanol production would not necessarily result in increased corn 

300 production. However, the removal of corn stover could lead to loss of soil surface cover if NRCS 

301 guidelines are not followed, thereby increasing runoff of nitrogen and phosphorus to surface 

302 waters, including wetlands (Kim and Dale, 2005). Even partial removal of corn stover can result 

303 in nutrient losses to water due to increased runoff (Kim and Dale, 2005; Lal, 2004). In addition, 

304 corn stover removal can lead to the loss of soil nutrients needed for corn growth, and higher 

305 fertilizer rates are likely to be required to sustain crop productivity, increasing the likelihood of 

306 increased runoff and transport of non-point source pollutants (Blanco-Canqui and Lal, 2009a).

307 Typically, for each ton of corn stover harvested, an additional 16 pounds of nitrogen fertilizer 
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308 and 6 pounds of phosphorus fertilizer must be added to the soil, though these quantities vary 

309 considerably (Sawyer and Mallarino, 2007). 

310 Mitigating the loss of nitrogen and other nutrients to water bodies is a research priority 

311 for the USDA. Since drainage systems are a key conduit for nutrient loading, new research is 

312 focusing on alternative surface and subsurface drainage solutions. An interagency Agricultural 

313 Drainage Management Systems Task Force, formed in 2003 and recently expanded, is working 

314 to reduce the loss of nitrogen and phosphorus from agricultural lands through drainage water 

315 management (CENR, 2010). One emerging conservation technology that addresses water quality 

316 degradation is the creation of wetlands on the perimeter of fields in order to receive surface 

317 runoff and filter out nutrients prior to its discharge into streams and rivers. Surface water runoff 

318 control, another conservation method used to stop water erosion, reduces the loss of nutrients to 

319 the surrounding environment through overland flow, but increases infiltration and loss of soluble 

320 nitrogen and phosphorus. A third strategy, lowering the water table during planting and 

321 harvesting, has been predicted to lower nitrogen losses in the Chesapeake watershed by 40 

322 percent (CENR, 2010). Other strategies, such as planting perennial grasses over subsurface tile 

323 drains or placing wood chips in drainage ditches, are also being explored. Implementing 

324 strategies such as these on agricultural lands that contribute a disproportionate share of nitrogen 

325 loads will maximize the environmental benefit of their application (CENR, 2010). 

326 However, none of these practices guarantee environmentally sustainable biofuel 

327 production on an industrial scale. The interactions between various BMPs need to be investigated 

328 more closely, as there can sometimes be unexpected adverse consequences from new 

329 technologies. For example, the 2010 report by the Committee on Environment and Natural 

330 Resources notes that the introduction of tile-drainage systems in the Midwest has improved 

331 agricultural yields but worsened water quality by accelerating nutrient-loaded runoff to streams 

332 and rivers without allowing natural processes to filter the nutrients (CENR, 2010). 

333 Nutrients—Coastal Waters Impacts 

334 Nutrient enrichment is a major concern for coastal waters across the U.S., including the 

335 Gulf of Mexico, Chesapeake Bay, other estuaries, and the Great Lakes. For example, almost 15 

336 percent of the coastal waters in the Gulf of Mexico and Northeast have poor water quality as 

337 measured by nutrient concentrations, extent of hypoxia, and water clarity (U.S. EPA, 2008b). 

338 The number of U.S. coastal areas documented as experiencing hypoxia increased from 12 in 

339 1960 to over 300 in 2008 (see Figure 3-4) (CENR, 2010). While these impacts are due to a 

340 number of types of nutrient inputs, such as lawn fertilizers, other agricultural uses, atmospheric 

341 deposition, and wastewater discharges, increased corn and soybean production for biofuel will 

342 likely increase nutrient loading in those watersheds where increased production occurs (CENR, 

343 2010). 
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344

345 Note: Map does not display one hypoxic system in Alaska and one in Hawaii.

346 Source: CENR, 2010.

347 Figure 3-4: Change in number of U.S. coastal areas experiencing hypoxia 

348 from 1960 to 2008 

349 Hypoxia in the Gulf of Mexico has been a long-standing environmental and economic 

350 issue that threatens commercial and recreational fisheries in the Gulf (U.S. EPA, 2010b). The 

351 primary cause of hypoxia in the Gulf of Mexico is excess nitrogen and phosphorus loadings from 

352 the Upper Midwest flowing into the Mississippi River, suggesting that increased corn and 

353 soybean production will exacerbate the problem (U.S. EPA, 2010b). U.S. Geological Survey 

(USGS) SPARROW12 354 modeling of the sources of nutrient loadings to the Gulf of Mexico 

355 estimated that agricultural sources contributed more than 70 percent of the delivered nitrogen 

356 and phosphorus to the Gulf of Mexico (Alexander et al., 2008). Corn and soybean production 

357 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 SWAT13

 

12 SPARROW (SPAtially Referenced Regressions On Watershed) is a watershed model developed by USGS 

relating water quality measurements at monitoring stations to other watershed attributes. The model estimates 

nitrogen and phosphorus entering a stream per acre of land, and evaluates the contributions of nutrient sources and 

watershed properties that control nutrient transport.

358 modeling 

359 indicated that, on average, it contributes 39 percent of the nitrogen load to the Gulf of Mexico, 

360 and 26 percent of the phosphorus load (SAB, 2007). One study estimated that corn production 

361 contributes between 60 and 99 percent of the total nitrogen load to the Mississippi River from 

362 eastern Iowa watersheds (Powers, 2007). Other studies have also determined that the majority of 

363 nitrate in the Mississippi River originates in the Corn Belt (Donner et al., 2004; Goolsby et al., 

364 1999). Nitrogen from fertilizers can also volatilize (and then return to water through atmospheric 

365 deposition). Atmospheric nitrogen from all sources, including power plant emissions, is 

366 estimated to contribute 15 to 20 percent of the nitrogen loading to the Gulf of Mexico (Alexander 

367 et al., 2008), and about 30 percent of the nitrogen loading to Chesapeake Bay (Paerl et al., 2002). 

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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368 A USDA study projects that reaching 15 billion gallons per year of ethanol from corn 

369 starch (i.e., not including stover) will result in a 1.7 percent increase in nitrogen loads to surface 

370 water, with the greatest increases in nitrogen load occurring in the Corn Belt and Northern Plains 

371 (Malcolm et al., 2009). EPA used the SWAT model to predict the impacts of increased corn 

372 production to meet the RFS2 corn starch ethanol targets on water quality in Upper Mississippi 

373 River Basin, which empties into the Gulf of Mexico. The modeling found a maximum increase 

374 in nitrogen load to the Gulf of Mexico of 1.9 percent, and a maximum of 1 percent increase in 

375 phosphorus load. The SWAT model also indicated that, by 2022, increased corn yields could 

376 reduce the need for increasing the amount of land in corn, so nutrient loads could decrease from 

377 earlier peaks (SAB, 2007).

378 Ecological features such as wetlands and riparian buffers play an important role in 

379 absorbing nutrients before they run into surface waters. Conserving wetlands where they exist, or 

380 creating artificial vegetated riparian buffers between waters and croplands, is a way to mitigate 

381 the impacts of nutrient loading. Riparian buffers and filter strips prevent potential pollutants in 

382 agricultural runoff (sediment, nutrients, pesticides, pathogens) from reaching surface waters. 

383 While the effectiveness of these buffers can vary depending on many factors, including slope, 

384 width, vegetation used, and how well they are maintained, studies have shown that they can 

385 remove up to 78 percent of phosphorous, 76 percent of nitrogen, and 89 percent of total 

suspended solids (TSS) (Schwer and Clausen, 1989).14

387 Nutrients—Ground Water Impacts 

386 

388 Excess nutrients from fertilizers can leach into ground water, which can discharge to 

389 surface waters, thereby contributing to surface water nutrient loading. About two-thirds of the 

390 nitrogen lost to subsurface flow eventually returns to surface water (U.S. EPA, 2010b, p. 971). 

391 Ground water can also be used for public and private drinking water supplies, and fertilizers can 

392 increase the concentration of nitrate in ground water wells, especially shallow wells (less than 

393 200 feet deep). USGS sampled 495 wells in 24 well networks across the U.S. in predominantly 

394 agricultural areas from 1988 to 2004 and found significant increases in concentrations of nitrate 

395 in 7 of the 24 well networks. In 3 of the 7 well networks, USGS found nitrate concentrations that 

396 exceeded the federal drinking water standards of 10 mg/L of nitrate-nitrogen (Rupert, 2008). 

397 Increased corn and soybean production for biofuels could worsen the problem of contaminated 

398 well water because of additional nitrogen inputs from fertilizer used to grow more corn. USDA 

399 projects that reaching 15 billion gallons per year of ethanol from corn will result in a 2.8 percent 

400 increase in nitrogen leaching to ground water, with the greatest increases occurring in the Great 

401 Lakes states and the Southeast (Malcolm et al., 2009). Similar estimates for soybean production 

402 were not identified. Studies of nitrate leaching from corn and soybean rotation cropping systems 

403 are inconclusive about whether these systems increase or decrease leaching rates (Kanwar et al., 

404 1997; Klocke et al.; 1999; Weed and Kanwar, 1996; Zhu and Fox, 2003). 

405 Fertilizer application management strategies aim to reduce nitrogen leaching by 

406 maximizing the efficiency of applied fertilizer. Such strategies focus on collecting precise 

407 information on soil nutrient content in order to better inform application rates. The USDA 

 

14 See also 

http://cfpub.epa.gov/npdes/stormwater/menuofbmps/index.cfm?action=factsheet_results&view=specific&bmp=82. 
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408 reports that phosphorus accumulation on farms has reached levels that often exceed crop needs

409 (ARS, 2003). Better information on these conditions could help reduce nutrient runoff that leads 

410 to eutrophication. There may also be economic incentives for implementing fertilizer 

411 management strategies. In 2006, the University of Minnesota Extension, an agricultural research 

412 partnership between federal, state and county governments, estimated that 86 percent of 

413 Minnesota farmers could save more than $6 per acre and 56 percent could save more than $10 

414 per acre in fertilizer costs by following better informed nutrient application rates (Minnesota 

415 Department of Agriculture, 2010). 

416 3.2.2.2 Sediment

417 Nutrients and sediment are the two major water quality problems in the U.S., and much 

418 attention has been focused on these issues in the Mississippi River Basin and the Gulf of Mexico 

419 (NRC, 2008, p. 88). Use of soil erosion control practices is widespread, yet 15 percent of acres in 

420 the Upper Mississippi River Basin experience excessive sediment loss (NRCS, 2010). The 

421 National Water Summary of Impaired Waters stated that in 2008 over 70,000 miles of streams 

422 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

436 Removal of corn stover from fields for use in biofuel production is expected to increase 

437 sediment yield to surface waters and wetlands, but rates are highly variable depending on soils, 

438 slope, management of fields, and the proportion of stover harvested (Cruse and Herndl, 2009; 

439 Kim and Dale, 2005). Results of SWAT modeling of the Upper Mississippi River Basin

440 (AquaTerra, 2010) indicated that leaving corn stover on fields helps reduce soil erosion and 

441 sediment transport, even when the amount of land in corn production increases. However, the 

442 amount of soil erosion that agricultural cropland experiences is a function of many factors, 

443 including not only residue left on the field, but also field operations (field preparation, tillage, 

444 etc.) in preparation for the next crop, timing of field operations, and other site-specific factors 

445 noted above (U.S. EPA, 2010b). 

Nelson et al. (2006) 423 reported 

424 that row crops, such as corn and soybean, result in higher erosion rates and sediment loads to 

425 surface waters, including wetlands, than non-row crops that might be used as biofuel feedstock, 

426 such as grasses. Sedimentation rates in agricultural wetlands can be higher than in natural 

427 grassland landscapes; increased sedimentation may, depending on sediment depths, cover viable 

428 seeds sufficiently to prevent germination (Gleason et al., 2003). EPA and USDA have evaluated 

429 the impact of the RFS2 rule on sediment loads. As reported in the water quality analysis 

430 conducted by EPA for the RFS2 rule, it is estimated that annual sediment loads to the Mississippi 

431 River from the Upper Mississippi River Basin would increase by 6.22 million tons (15 percent) 

432 between 2005 and 2022, assuming corn stover remained on the field following harvest 

433 (AquaTerra, 2010). A USDA study estimates that nationally, sediment loads in 2015 will be 1.6 

434 percent greater with implementation of RFS2 than without, assuming ethanol production from 

435 corn starch only (Malcolm et al., 2009). 

 

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

461 3.2.2.3 Pesticides

446 can 

447 reduce erosion by leaving at least 30 percent of the ground covered by crop residue and by 

448 limiting soil disturbance. According to the USDA, 41 percent of planted acreage in the U.S. uses 

449 conservation tillage as a mitigation strategy (ARS, 2006). These techniques have been shown to 

450 reduce erosion by as much as 60 to 90 percent, depending on the conservation tillage method 

451 (Minnesota Department of Agriculture, 2010). In 2002, the USDA Agricultural Research Service 

452 studied the effect of ridge tillage on Northern Corn Belt plantations. The study showed that ridge 

453 tillage not only reduced erosion and sediment loading but also increased profitability, reduced 

454 fuel and labor use, and reduced economic risk relative to conventional tillage for a corn and 

455 soybean rotation (ARS, 2006). Additionally, these alternative tillage approaches can reduce trips 

456 across the field, lowering fuel use and improving the energy balance of the resulting biofuel. The 

457 use of conservation tillage, in combination with BMPs, such as cover crops, may partially 

458 compensate for the increase in erosion potential caused by cover stover removal (Blanco-Canqui 

459 and Lal, 2009b). Depending on the soil type, these practices may allow a percentage of stover to 

460 be harvested sustainably (Blanco-Canqui and Lal, 2009b). 

462 According to the National Summary of Impaired Waters(i.e., waters that do not meet the 

463 water quality standards) (U.S. EPA, 2009a, 2010d), over 16,000 miles of streams and rivers and 

464 over 370,000 acres of lakes and reservoirs in the U.S. were impaired in 2008 because of 

465 pesticides, with atrazine (commonly used in corn production) specifically cited by several states

466 (U.S. EPA, 2010c). Atrazine was also estimated to be the most common pesticide lost from 

467 agricultural lands in the Upper Mississippi River Basin (NRCS, 2010). 

468 Corn production uses more pesticides than predicted for any other potential biofuel crop 

469 produced in the U.S. (Pimentel and Patzel, 2005; Pimentel and Pimentel, 2008, p. 380; Ranney 

470 and Mann, 1994). USDA’s NASS estimates that insecticides were applied to 16 percent of the 

471 2006 soybean-planted acreage (NASS, 2007b). USDA also estimates that herbicides were 

472 applied to 98 percent of the planted soybean acreage in 2006. Soybean production releases less 

473 pesticide to surface and ground water per unit of energy gained (Hill et al., 2006). 

474 While effective pest control may be critical to achieving the yield gains that underpin 

475 EISA biofuel projections and targets (Perkins, 2009), there are risks associated with the use of 

476 pesticides. The FIFRA registration process is intended to minimize these risks. Many factors 

477 contribute to the relative risks of pesticides on the environment, including fate and transport 

478 characteristics, method of application, depth to ground water, and proximity to receiving waters. 

479 To protect consumers against risks posed by ingestion of these pesticides, FFDCA requires the 

480 establishment of pesticide residue tolerances on food using a standard of reasonable certainty of 

481 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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482 Growing continuous corn (rather than in rotation with other crops) can increase 

483 population densities of pests such as the corn rootworm, resulting in increased pesticide 

484 applications to control these pest species (Whalen and Cissel, 2009). A USDA study projects that 

485 cropland dedicated to continuous corn will increase by more than 4 percent by 2015 to reach the 

486 15 billion gallons per year of ethanol from corn target (Malcolm et al., 2009). In addition, 

487 increases in corn acreage and any conversion to corn of crops other than corn will most likely 

488 increase total herbicide use. Increased corn and soybean production can result in the increased 

489 use of herbicides that can run off or leach into surface water or ground water sources. 

490 Integrated pest management (IPM) practices may help reduce pesticide use by tailoring 

491 treatment to pest infestation cycles, and by more precisely targeting the amount and timing of 

492 applications. IPM focuses on extensive monitoring of pest problems, comprehensive 

493 understanding of the life cycles of pests and their interaction with the environment, and very 

494 precise timing of pesticide applications to minimize pesticide use. In addition to providing 

495 environmental benefits of lower pesticide use, IPM often results in lower chemical pesticide 

496 expenses and pest damage to crops, as well as preventing the development of pesticide-resistant 

497 pests (Minnesota Department of Agriculture, 2010). The use of cover crops is an IPM practice 

498 that can dramatically reduce chemical application and soil erosion. USDA research in the 

499 Midwest in 2006 demonstrated that autumn-planted small grain cover crops reduced soil erosion, 

500 nitrate leaching, and suppressed weeds (Teasdale et al., 2007). 

501 National adoption of IPM strategies varies. Corn and soybean growers reported scouting 

502 for weeds, insects, and diseases on 50 percent of acres or more in 2000, but reported adjusting 

503 planting or harvest dates to manage pests on less than 20 percent of acres (Weibe and Gollehon, 

504 2006). 

505 3.2.2.4 Pathogens and Biological Contaminants 

506 The use of animal manure as a fertilizer has been tied to an increased risk of viruses and 

507 bacteria leaching into the water supply. Pathogens such as Salmonella sp., Campylobacter sp., 

508 and Clostridium perfringens—along with additives such as livestock antibiotics and hormones—

509 may be released into surface or ground water when manure is applied to fields (Brooks et al., 

510 2009; Lee et al., 2007a; Unc and Goss, 2004). The USDA Report to Congress on use of manure 

511 for fertilizer and energy reports that approximately 12 percent of corn and 1 percent of soybeans 

512 are fertilized with manure (MacDonald et al., 2009). 

513 The flow paths by which pathogens can contaminate ground or surface water are the 

514 subject of current research. Transport through soil has been shown to remove harmful bacteria in 

515 some cases, though this may depend on soil characteristics, the hydrologic regime (i.e., distance 

516 to surface or ground water) and the pathogens in question (Malik et al., 2004; Unc and Goss, 

517 2004). Contamination rates likely are greater where there is higher runoff relative to infiltration, 

518 a high water table, or a direct surface-ground water connection. Implementation of manure 

519 management practices, such as covering or storage at elevated temperatures prior to application 

520 can reduce runoff. In addition, applying manure during times of low runoff potential can reduce 

521 the risk of water contamination (Moore et al., 1995; Guan and Holley, 2003). 
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522 3.2.3 Water Quantity 

523 3.2.3.1 Water Use 

524 Over the entire biofuel supply chain (see Figure 2-3 in Chapter 2), crop irrigation is by 

525 far the most significant use of water in the ethanol production process, and it tends to be much 

526 higher than water use for most other non-renewable forms of energy on an energy content basis 

527 (Wu et al., 2009). In some geographic locations this could lead to serious impacts on already 

528 stressed water supplies, while in other locations water supply availability impacts are less likely 

529 to occur. Future assessment of biofuel feedstocks will need to consider restrictions on water use 

530 due to competing demand for water resources (Berndes, 2002). 

531 For both corn and soybeans, the source for water used to irrigate crops varies from region 

532 to region. In the West, surface water is largely used to irrigate crops; in the Great Plains and 

533 Midwest, where the majority of corn and soybean production takes place, farmers rely heavily on 

534 ground water (Kenny et al., 2009). In the future, as corn production increases to meet ethanol 

535 demands, both geographical factors and the type of land/crop conversion will determine water 

536 use impacts. Water use will increase as land in pasture or other low- or non-irrigated uses are 

537 converted to irrigated corn production, especially in places like the Great Plains, where water 

538 demand for corn irrigation is high. Converting other crops, soybeans in particular, into corn will 

539 have little effect on water use in the Midwest, but could increase the total amount of water used 

540 for irrigation in the Plains because of corn’s relatively high water use intensity on a per area 

541 basis (NRC, 2008). 

542 Corn 

543 Corn is relatively water-intensive compared to other crops. In some parts of the country, 

544 water demands for corn are met by natural rainfall, while in other places supplemental irrigation 

545 is required. For instance, in Iowa in 2007, less than 1 percent of the more than 14 million acres 

546 planted in corn was irrigated. In contrast, over 60 percent of Nebraska’s 9.5 million acres of corn 

547 was irrigated in the same year (NASS, 2009). 

548 Irrigation use for U.S. corn has been estimated to vary from a low of approximately 8 

549 gallons of water per gallon of ethanol on average in Midwest states in one study (Wu et al., 

550 2009) to a high of up to 1,000 gallons for states in the Great Plains in another study (Dominguez551 Faus et al., 2009). While the data and methodology used to calculate these estimates are not 

552 uniform across studies, in general, water use is likely to be less than 500 gallons (perhaps 

553 substantially less) of irrigation water per gallon of ethanol in the Midwest and greater than 500 

554 gallons per gallon of ethanol in more arid parts of the country (supporting information for Chiu 

555 et al., 2009). Taking into account the total volume of corn starch ethanol produced, this might 

556 translate into approximately 5 billion gallons of irrigation water in a single season in places like 

557 Iowa and Illinois versus 300 billion gallons in Nebraska (Chiu et al., 2009). The 2007 U.S. 

558 national ethanol-production-weighted average farm-to-fuel pump water requirement per gallon 

559 of ethanol in the U.S. was estimated to be 142 gallons (Chiu et al., 2009). 
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560 Corn Stover 

561 Allocation of proportionate water use based on the energy captured from corn starch 

562 versus stover may be studied in the future as corn stover becomes a more common biofuel 

563 feedstock. Water use for corn stover above and beyond corn cultivation is likely to be minimal or 

564 negligible if undertaken with resource conservation practices, especially in the most productive 

565 corn-growing regions of the U.S. where corn stover is not functionally necessary for retention of 

566 soil moisture. If, however, corn stover is removed from dry corn cultivation areas with 

567 supplemental irrigation (states like Nebraska), loss of soil moisture that would have otherwise 

568 been retained by corn stover cover and contributed to productivity of the next season’s crop 

569 (Blanco-Canqui and L al., 2009b) could necessitate additional irrigation. 

570 Soybeans 

571 Water for soybean cultivation, like corn, also comes from both natural precipitation and 

572 through irrigation. In some places, the water requirements are largely met with precipitation. For 

573 example, in 2007 in the leading soybean-producing state of Iowa, 8.6 million acres of soybeans 

574 were grown of which less than 1 percent was irrigated (NASS, 2009). In 2007 Nebraska grew 3.8 

575 million acres of soybeans, of which over 40 percent was irrigated (NASS, 2009). 

576 Average nationwide rates of soybean irrigation are estimated at 3,000 to 6,000 gallons of 

577 irrigation water to produce a volume of biodiesel equivalent to a gallon of gasoline (U.S. DOE, 

578 2006; Dominguez-Faus et al., 2009). These rates are not applicable to states such as Iowa, where 

579 most soybeans are grown without irrigation. In Nebraska, however, where irrigation is heavily 

580 utilized, greater than 4,000 gallons of irrigation water per gallon of gas equivalent is not an 

581 unusual investment of water resources for biofuel production (supplemental information to 

582 Dominguez-Faus et al., 2009). Overall, irrigation estimates for soybeans tend to be greater than 

583 those needed to produce a volume of corn starch ethanol equivalent to a gallon of gasoline 

584 (Dominguez-Faus et al., 2009). 

585 3.2.3.2 Water Availability 

586 Because agriculture accounts for such a large share of water use in the U.S. (35 percent of 

587 withdrawals nationwide in 2005, and a much larger percentage in some parts of the country, 

588 according to Kenny et al., 2009), changes in agricultural production could impact future water 

589 availability. In particular, land conversion to corn for increased production of ethanol could 

590 create more demand for water, adding to existing water constraints and potentially creating new 

591 ones. The Great Plains states already have shortages, and water availability may decrease further 

592 when typically non-irrigated pasture and CRP land is converted to irrigated corn production. 

593 Converting other crops, soybeans in particular, into corn will have little effect on water use and 

594 availability in the Midwest, but could increase the total amount of water used for irrigation in the 

595 Plains because corn requires more water than soybeans on a per area basis in that region (NRC, 

596 2008). 

597 To a large extent, the current capacity to produce biodiesel from soybeans resides in 

598 states with rain-fed soybean cultivation. Such strategic siting of biodiesel production facilities 

599 minimizes both demands for irrigation water for biodiesel feedstock and potential conflicts over 
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600 water availability required for other purposes such as power generation, public water use, and 

601 recreation. However, if biodiesel production develops in places requiring greater soybean 

602 irrigation such as the Great Plains, water availability could be reduced. This is especially true if 

603 irrigated soybean cultivation replaces other low or non-irrigated land uses. Because over 85 

604 percent of irrigation withdrawals come from underground aquifers, ground water availability is 

605 likely to be affected the most.

606 Both surface water and ground water withdrawals can negatively impact aquatic life. 

607 Surface water withdrawals can reduce flood flows (or peak flow regimes), as well as reduce total 

608 flow (or discharge) during summer months when irrigation requirements are high and surface 

609 water levels are low (Poff and Zimmerman, 2010). Ground water availability is largely affected 

610 by ground water withdrawals for irrigation. The consequences of excessive ground water 

611 withdrawal can include reduced water quality, prohibitive increases in the costs of pumping, 

612 reduced surface water levels through hydrological connections, and subsidence (Reilly et al., 

613 2008). Several regions (e.g., High Plains aquifer, Lower Mississippi River alluvial aquifer) that 

614 are already experiencing water shortages could be substantially impacted by increased corn 

615 production for ethanol. Ground water withdrawals also have indirect impacts on stream flow. 

616 Withdrawals from hydrologically connected aquifers can lower base flow to rivers and streams 

617 that depend on ground water to maintain year-round stream flow. In some areas, stream flow has 

618 been reduced to zero because of ground water depletion, but in other areas, minimum stream 

619 flow during the summer has been sustained because of irrigation return flow to streams 

620 (Bartolino and Cunningham, 2003). 

621 3.2.4 Soil Quality

622 3.2.4.1 Soil Erosion 

623 Soil erosion can have substantial negative effects on soil quality by preferentially 

624 removing the finest, uppermost soil particles, which are higher in organic matter, plant nutrients, 

625 and water-holding capacity relative to the remaining soil (Brady and Weil, 2000). The soil 

626 erosion impact of growing corn or soybeans for biofuel will vary, largely depending on the 

627 particular land use/land-cover change and tillage practices. Conversion of uncultivated land, such 

628 as CRP acreage, to corn or soybeans for biofuels is the land use change scenario most likely to 

629 increase erosion and sedimentation. The USDA CEAP report on the Upper Mississippi River 

630 Basin found that for land in long-term conserving cover, like CRP, soil erosion and sediment loss 

631 were almost completely eliminated (NRCS, 2010). Moreover, CRP acreage in riparian areas 

632 slows runoff, promoting the deposition of sediment, nutrients, and other chemicals. The USDA’s 

633 Farm Service Agency estimated that, in 2008, CRP land collectively prevented 445 million tons 

634 of soil from eroding (FSA, 2009). The soil-erosion effects of converting former or current 

635 pasture land to corn will vary depending on prior erosion rates. Pasture land in the U.S. Southern 

636 Piedmont region, for example, can exhibit soil stability equal to forested or conservation-tilled 

637 land; converting this type of land to conventional corn production will increase soil erosion 

638 (Franzluebbers et al., 2000). In contrast, if much of the increase in corn or soybean production 

639 comes from a shift from other crops (in 2007, for example, the increase in corn acreage came 

640 predominantly from a decrease in soybeans), the effect on soil erosion is likely to be much 

641 smaller. Allocation of a higher percentage of corn or soybeans for biofuel production to land 

642 currently in agricultural use likely will not alter soil erosion rates.
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643 Tillage practices can mitigate soil erosion on current agricultural lands. Conventional 

tilling17

657 Finally, removal of corn stover beyond a certain threshold may increase soil erosion 

658 rates. Due to this and cost concerns, a recent study suggested that only approximately 30 percent 

of corn stover

644 breaks up soil aggregates, increasing erosion by wind and water (Lal, 2003). In contrast, 

645 conservation tillage—defined as practices that maintain at least 30 percent of the ground covered 

646 by crop residue (Lal, 1997)—can considerably reduce soil erosion (Cassel et al., 1995; Shipitalo 

647 and Edwards, 1998). No-till agriculture, a type of conservation tillage, disturbs the soil only 

648 marginally by cutting a narrow planting slit. According to the CEAP report, conservation tillage 

649 is practiced on 96 percent of all crop acreage in the Upper Mississippi River Basin, with 23 

650 percent in no-till, and only 5 percent in continuous conventional tillage (NRCS, 2010). 

651 Conservation tillage practices may also partially mitigate the impact of converting CRP acreage 

652 to biofuel corn production (Follett et al., 2009). A majority of CRP acreage in areas of the 

653 Midwest are classified as highly erodible land, where tillage practices are generally restricted by 

654 the conservation compliance provisions of the 1985 Food Security Act (Secchi et al., 2009). 

655 These compliance provisions can require corn-soybean rotations with no-till cultivation (Secchi 

656 et al., 2009). 

18

668 3.2.4.2 Soil Organic Matter

659 would be available for sustainable harvesting in the U.S. if erosion rates were to 

660 be kept lower than soil loss tolerances (T-values) as defined by the USDA NRCS (Graham et al., 

661 2007). Because of wind erosion, the potential for corn stover removal in the Western Plain states 

662 may be particularly limited (Graham et al., 2007). Site cultivation practices may partially 

663 compensate for the effects of residue removal. If no-till agriculture were universally adopted, 

664 sustainably harvested corn stover supplies are estimated to increase from approximately 30 to 50 

665 percent (Graham et al., 2007). Yet, even with no-till management, corn stover removal rates at or 

666 higher than 50 percent have been shown to increase erosion potential (Blanco-Canqui and Lal, 

667 2009a). 

669 Soil organic matter is critical because it retains plant nutrients and water, facilitates 

670 carbon sequestration, promotes soil structure, and reduces erosion. The impact of corn and 

671 soybean production for biofuel on soil organic matter will depend on the cultivated acreage. 

672 Corn production will negatively impact soil quality on acreage where organic matter has 

673 accumulated over time—for example, grasslands. If conventional tilling is used, a loss of organic 

674 matter both to erosion and to the atmosphere as carbon dioxide due to increased microbial 

675 decomposition is likely to occur (Reicosky et al., 1995). Estimates of carbon loss following 

676 conventional tilling of previously undisturbed soils range from 20 to 40 percent—although how 

677 much carbon is respired to the atmosphere versus lost to erosion is unclear (Davidson and 

678 Ackerman, 1993). Assuming carbon loss to the atmosphere, it has been estimated that conversion 

679 of grasslands in CRP to corn production would create a carbon debt requiring approximately 48 

680 years to repay (Searchinger et al., 2008). In contrast, increased corn or soybean production on 

681 currently cultivated land will have a smaller effect on soil organic matter, particularly where 

682 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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683 Borbe et al., 2007; Drinkwater et al., 1998; Lal, 2003). While soil quality degrades over time, 

684 yields and production can be maintained by the use of fertilizers both commercial and organic. 

685 The harvesting of crop residues, such as corn stover, removes plant material that would 

686 otherwise remain on and potentially be incorporated into the soil. The removal of corn stover 

687 therefore has important implications for soil quality, chiefly via effects on soil retention, organic 

688 matter content, nutrients, and compaction. Stover removal rates of 25 to 75 percent have been 

689 shown to decrease soil organic matter across several soil types even under no-till management

690 (Blanco-Canqui and Lal, 2009a). Therefore, there is concern that high stover removal rates may 

691 decrease soil carbon sequestration and lower crop yields (Karlen et al., 2009). Whatever the 

692 removal rate for a particular site, it has been recommended that soil erosion and organic matter 

693 content be periodically monitored to allow stover removal rates to be adjusted accordingly 

694 (Andrews, 2006). The effects of crop residue removals on crop yields have been shown to be 

695 highly variable depending on soil type, climate, topography, and tillage management, among 

696 other characteristics (Blanco-Canqui and Lal, 2009b). Research to date suggests corn stover 

697 removal rates should be determined based on site-specific criteria to maximize soil quality.

698 3.2.5 Air Quality

699 Air quality impacts during cultivation and harvesting of corn and soybeans are associated 

700 with emissions from combustion of fossil fuels by farm equipment and from airborne particles 

701 (dust) generated during tillage and harvesting. Soil and related dust particles (e.g., fertilizer, 

702 pesticide, manure) become airborne as a result of field tillage, especially in drier areas of the 

703 country. In addition, emissions result from the production of fertilizers and pesticides used in 

704 corn and soybean production, and the application of fertilizers and pesticides to each crop. Air 

705 emissions associated with cultivation and harvesting of corn and soybeans for biofuel will mostly 

706 occur in sparsely populated areas. Subsequent stages in the biofuel supply chain (see Figure 2-3), 

707 including feedstock logistics and biofuel production, distribution, and use, also affect air quality 

708 and are discussed in Chapter 4. 

709 3.2.5.1 Cultivation and Harvesting

710 Cultivating and harvesting corn and soybeans require a range of mechanized equipment 

711 that utilize different fuels, including diesel, gasoline, natural gas, and electric power (Sheehan et 

712 al., 1998a). Generally, equipment used to produce corn and soybeans consumes more diesel than 

713 for most other crops, while the rate of gasoline consumption is somewhat less than that of other 

714 crops. Primary emissions from fuel use include nitrogen oxides (NOx), volatile organic 

715 compounds (VOCs), carbon monoxide (CO), sulfur dioxide (SO2) (primarily from gasoline), and 

716 coarse and fine particulate matter (PM10 and PM2.5). Gasoline use may also result in benzene, 

717 formaldehyde, and acetaldehyde emissions. For corn, approximately 14 gallons of diesel fuel is 

718 used per acre for tillage, harvest, and hauling. Fuel use for tillage comprises more than half of 

719 this amount; actual usage depends on soil properties and conditions (Iowa State University, 

720 2009). With respect to corn stover, additional fuel use depends on the method of stover harvest. 

721 For example, methods that can simultaneously collect grain and stover will use less fuel than 

722 those requiring multiple passes with a harvester. For this reason, one-pass harvesters are 

723 currently being developed and tested (Shinners et al., 2009). 
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724 Emissions are also associated with generation of electricity used for irrigation water 

725 pumping. Irrigation power needs are estimated to range from 3 to 11 kilowatt-hours (kWh) per 

726 irrigated acre, depending on the region, with a national average of 8 kWh per irrigated acre. For 

727 soybean cultivation, electricity use is estimated to be 4.6 kWh per acre (Sheehan et al., 1998a). 

728 Emissions associated with this use depend on the source of the electricity consumed. Coal is the 

729 predominant fuel source for electricity in the Midwest, accounting for 71.3 percent of generation 

730 in the 12 primary corn-producing states. Coal-fired power plants are significant sources of SO2, 

731 NOx, carbon dioxide (CO2), and mercury emissions.

732 Corn with a moisture content of over 18–20 percent may require drying prior to storage 

733 to avoid spoilage (South Dakota State University, 2009). Grain driers use liquid petroleum gas 

734 (LPG) and electricity. LPG and electricity use depend on grain moisture content at harvest. For 

735 example, typical Midwest grain harvest conditions and yields require 20 gallons of LPG per acre 

736 harvested. The exact amount depends on grain moisture conditions at harvest. 

737 3.2.5.2 Fertilizers and Pesticides 

738 Pesticides are commonly used on both corn and soybeans, with corn having more 

739 intensive application rates (NRC, 2008, p. 3, as cited in U.S. EPA, 2010b) than soybeans. Corn 

740 has the highest nitrogen fertilizer use per acre of any biofuel feedstock. Because soybeans are 

741 legumes, they require much lower amounts of fertilizer, particularly nitrogen (NASS, 2006, 

742 2007b). Soybeans have the capacity to derive nitrogen from the atmosphere and therefore require 

743 less external nitrogen fertilization than corn, resulting in less nitrogen runoff in the surface water. 

744 Air emissions associated with fertilizer manufacturing and transport include NOx, VOC, 

745 CO, and particulate matter (PM10 and PM2.5), while pesticide production and blending may result 

746 in emissions of 1,3-butadiene, benzene, and formaldehyde. 

747 Application of fertilizers and pesticides may result in releases to the air and volatilization 

748 of pesticide ingredients. The primary pollutants associated with the releases to air are benzene 

749 and acrolein. The results described are consistent with another study, which found increases in 

750 benzene, formaldehyde, acetaldehyde, and butadiene emissions, although that study included 

751 feedstock transport and so is not directly comparable (Winebrake et al., 2001). Emissions of CO, 

752 NOx, and SO2 increased with the use of corn stover as a feedstock in a hypothetical system (i.e., 

753 a simulation based on corn stover life-cycle data), with higher NOx emissions mainly due to 

754 denitrification of increased amounts of nitrogen fertilizers added to farm soils (Sheehan et al., 

755 2004). 

756 3.2.6 Ecosystem Impacts 

757 3.2.6.1 Eutrophication, Erosion, and Biodiversity Loss 

758 The impact of increased corn and soybean cultivation on ecosystem and biodiversity 

759 depends, in large part, on where crop production occurs and what management techniques are 

760 used. Major ecosystem-related impacts that could result from additional corn and soybean 

761 production are eutrophication, soil erosion and its associated increase in turbidity of receiving 

762 waters and sedimentation in basins, and impacts to biodiversity. Eutrophication can occur as 

763 fertilizer application increases nutrient loadings (nitrogen and phosphorus) in surface waters such 
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764 as streams, rivers, lakes, wetlands, and estuaries (U.S. EPA, 2010b). Increased phosphorus 

765 concentration has been correlated with declines in invertebrate community structure, and high 

766 concentrations of ammonia nitrogen are known to be toxic to aquatic animals. Severe oxygen

767 depletion and pH increases, both of which are correlated with eutrophication, have been known 

768 to cause growth problems and mortality in fish and invertebrates (U.S. EPA, 2010b). In addition, 

769 as aquatic systems become more enriched by nutrients, algal growth can cause a shift in species 

770 composition. Hypoxia threatens commercial and recreational fisheries in the Gulf of Mexico 

771 (U.S. EPA, 2010b) and limits biodiversity (Wang et al., 2007a). 

772 Soil erosion can also lead to an increase in wetland sedimentation, which may, depending 

773 on sediment depths, cover viable seeds sufficiently to prevent germination (Gleason et al., 2003). 

774 In aquatic ecosystems, sediments increase turbidity and water temperatures and bury stream 

775 substrates, limiting habitat for coldwater fish (U.S. EPA, 2006a). 

776 In areas where corn production is already significant, increased corn acreage can further 

777 reduce landscape diversity (Landis et al., 2008), which might in turn impact other aspects of 

778 biological diversity and the ecosystem services associated with biodiversity. In Iowa, Michigan, 

779 Minnesota, and Wisconsin, biological control of soybean aphids was found to decline as the 

780 proportion of corn in the local landscape increased, resulting in increased expenditures for 

781 pesticides and reduced yields (Landis et al., 2008). In the Prairie Pothole region of Iowa, 

782 Minnesota, North Dakota, and South Dakota, landscapes with higher proportions of corn acreage 

783 had comparatively fewer grassland bird indicator species (Brooke et al., 2009). If landscape 

784 diversity decreases (especially in the case of transforming CRP land into corn production), 

785 migratory birds will lose habitat and likely decline in numbers. On CRP lands, several grassland 

786 bird species have increased in abundance, and it is estimated that, without the 3 million hectares 

787 of CRP in the Prairie Pothole region of the U.S., over 25 million ducks would have been lost 

788 from the annual fall migratory flights between 1992 and 2004 (Dale et al., 2010). 

789 The removal of corn stover residues from agricultural corn fields for ethanol production 

790 has potential consequences on aquatic ecosystems and local biodiversity. Removing crop 

791 residues from farm fields has been shown to affect both terrestrial and soil biota. Crop residue 

792 removal has been correlated with decreases in the diversity of biota (Lal, 2009; Johnson et al., 

793 2006). 

794 Intensification of soybean production and pesticide use may also threaten biodiversity 

795 and nearby biota (Artuzi and Contiero, 2006; Koh and Ghazoul, 2008; Pimentel, 2006). The 

796 change in local habitat from corn-soybean-corn rotation to continuous corn production may 

797 decrease the support for biological control in soybean cropping systems, as reduced landscape 

798 diversity decreases the habitat availability of many insects and animals in the local region 

799 (Landis et al., 2008). Also, agricultural herbicides affect the composition of local plant 

800 communities, which then affects the abundance of natural enemy arthropods and the food supply 

801 of local game birds (Taylor et al., 2006). Fungicide pollution from runoff events has been shown 

802 to impact algae and aquatic invertebrates in areas where soybeans are intensively grown (Ochoa803 Acuna et al, 2009). 
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804 3.2.6.2 Invasive Plants

805 Modern varieties of corn and soybeans under production today in the U.S. pose little risk 

806 of dispersing seeds or regenerative plant parts or creating hybrids with related plants that will 

807 become weeds or invasive plants in the future. Corn and soybeans rarely overwinter successfully 

808 in major production areas, but on occasion, seed from the previous year’s crop can emerge in the 

809 following year and the plants persist through a single growing season as a weed. Such 

810 populations of plants do not become a chronic problem, however, because they do not sustain 

811 themselves (Owen, 2005). To date, no cases of invasive corn or soybeans have ever been 

812 reported in natural areas in the U.S. However, since U.S. seed and biotechnology companies 

813 working to improve feedstocks may propagate corn in areas such as Mexico where corn and its 

814 progenitors originated, it is possible that novel corn cultivars or their hybrids could spread 

815 beyond the cultivated fields and survive. This potential for intermixing genetically modified 

816 plants with ancestral land acres is the subject of international scientific and regulatory interest 

817 (Mercer and Wainwright, 2008). 

818 The extensive cultivation of row crops that are genetically engineered to resist the 

819 herbicide glyphosate may result in indirect effects on other weed species and invasive plants. 

820 One study correlated the increased use of this herbicide with the appearance of glyphosate 

821 resistance in at least ten agricultural weeds in the U.S.; loss of effectiveness of glyphosate could 

822 encourage the use of more toxic herbicides (NRC, 2010). 

823 3.2.7 Assessment

824 Corn and Soybean Acreage: Between September 2010 and August 2011, approximately 

825 38.4 percent of corn consumed domestically is projected to be converted into ethanol biofuel 

826 (NASS, 2010a; ERS, 2010c). Corn acreage has increased over 2005 levels in part due to ethanol 

827 demand, and planted acreage is expected to increase from 2008/2009 levels of 85.9 million acres 

828 to 90 million acres in 2019 to meet the 15 billion gallons per year annual target under EISA 

829 (USDA, 2010c). Currently, 5.6 percent of the soybean harvest goes to biodiesel production, and 

830 USDA expects this percentage to increase to 7.8 percent by 2012 and hold steady through 2019. 

831 USDA also expects that soybean acreages will hold steady at 76 million acres, though this 

832 number may be higher to meet the EISA target. Moreover, it may be necessary to increase 

833 acreage yield, or the portion of the soybean harvest that is devoted to biodiesel in order to meet 

834 EISA targets (FAPRI, 2010a). Use of corn stover for ethanol production is not expected to 

835 increase acreage dedicated to corn.

836 Land Use/Land Cover Change: Much of the environmental impact of corn starch ethanol 

837 and soybean biodiesel production depends on the types of land put into cultivation. To date, most 

838 additional acreage has originated from lands currently in crop production. Expanding corn crop 

839 production to CRP or previously uncultivated acreage will likely have varying degrees of 

840 environmental impacts, depending on site-specific characteristics.

841 Water Quality: Increasing production of corn for ethanol and soybeans for biodiesel may 

842 have implications for water quality. Increased corn and soybean production could increase 

843 nutrient, sediment, and pesticide loadings to water bodies, including the Gulf of Mexico, Great 

844 Lakes, and Chesapeake Bay. Private drinking water wells could see increases in nitrate and 
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845 public drinking water systems could see increases in their costs to lower nitrate levels. However, 

846 some of the potential increased nutrient loadings from corn grown for ethanol might be offset by 

847 increasing per-acre corn and soybean yields and by implementing comprehensive conservation 

848 systems. Increased risk of pathogens entering surface waters from application of animal manure 

849 fertilizers is also possible. Removal of corn stover could lead to loss of soil surface cover, 

850 thereby increasing runoff of nitrogen and phosphorus to surface waters; harvesting corn stover 

851 may reduce soil nutrient availability, leading to increased fertilizer applications

852 Water Availability: The magnitude of environmental impact from increased corn and/or 

853 soybean production for biofuel will vary geographically. If corn replaces other crops in the 

854 Midwest, water availability will be minimally impacted. Increased corn and soybean production 

855 in areas requiring irrigation, such as the Great Plains, will increase water usage, potentially 

856 decreasing water availability. Removal of corn stover for ethanol will not affect water 

857 availability in most parts of the U.S.

858 Soil: Impacts of expanding corn and soybean production will vary, depending on the 

859 converted land use. Negative soil quality impacts will arise from converting acreage protected 

860 with perennial vegetation to conventional corn and soybean production, which will likely 

861 increase soil erosion, sedimentation, and nutrient losses. Removal of corn stover for ethanol may 

862 lead to a decline in organic matter, decreasing soil carbon sequestration and adversely impacting 

863 crop yields. Impacts can be minimized through site-specific BMPs that limit soil erosion and 

864 ensure that the amount of residue remaining on the field sustains soil quality and nutrient inputs 

865 for subsequent crop productivity. 

866 Air Quality: An increase in the production of corn and soybean for biofuel will likely 

867 lead to increased pollution from fossil fuels associated with cultivation and harvesting and from 

868 airborne particles (dust) generated during tillage and harvesting. Air emissions also result from 

869 the production of fertilizers and pesticides used in corn and soybean cultivation, and the 

870 application of fertilizers and pesticides for each crop. Increasing their use will likely increase the 

871 volume of emissions. 

872 Ecosystem Health/Biodiversity: Ecosystem health/biodiversity impacts include 

873 degradation of aquatic life due to eutrophication, impaired aquatic habitat due to sedimentation 

874 from soil erosion, and decreases in landscape diversity. Conversion of CRP lands, which are 

875 predominantly grasslands, may lead to declines in grassland birds, ducks, and other wildlife that 

876 use these lands as habitat.

877 Invasive Species: Corn and soybean typically are not invasive in the U.S. corn and 

878 soybean-growing regions.

879 3.2.7.1 Key Uncertainties and Unknowns

880 Uncertainties and a scarcity of data exist in many key areas concerning environmental 

881 impacts of biofuel feedstock production. In particular: 

882 • The impacts of additional soybean and corn production are determined by where 

883 the production occurs and the types of management practices employed, including 
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884 the extent of tile drainage. However, it is highly uncertain where production will 

885 occur and the extent to which BMPs will be employed. In particular: 

 886 

887 — Increased corn and soybean yields may offset the need for increased acres 

888 in production to achieve EISA goals in 2022. However, the extent to 

889 which yield increases will occur is currently unknown, and thus the extent 

890 to which increased production of corn and soybeans will occur on 

891 marginal lands, CRP, and/or via continuous corn production on existing 

892 lands now in rotation with other crops is also uncertain. 

 893 

894 — The extent to which BMPs are currently implemented on cropland 

895 nationally is unknown, and the potential for future improvements, 

896 including improvements in yield; management of nutrients, pesticides, 

897 drainage, and energy use; and erosion control systems, is also uncertain. 

 898 

899 • The ability to track impacts will depend on the quality and consistency of 

900 monitoring fertilizer and pesticide usage, such as data provided by USDA’s 

901 National Agricultural Statistics Services.

 902 

903 • The ability to evaluate current and future water shortages associated with ethanol 

904 and biodiesel production is limited by the available data. Annual measurements of 

905 the extent of irrigation and amounts of surface and ground water used are not 

906 systematically collected nationwide, forcing researchers to use incomplete 

907 information to calculate crude water use estimates. Estimates of water use to 

908 produce soybeans for biodiesel are even less certain than those for corn 

909 production. The connection between water use for corn and soybean production 

910 and impacts on water availability and water shortages is also surrounded by 

911 uncertainty. The availability of fresh water for a particular use is determined by 

912 many factors, including rainfall, soil water retention and ground water recharge, 

913 water demand for competing uses, and water contamination; attribution of water 

914 shortages to a specific use may be difficult to measure without improvements in 

915 data collection (Alley et al., 2002; Reilly et al., 2008). 

 916 

917 • The uncertainties regarding the effect of corn and soybean production on soil 

918 quality arise predominantly from uncertainties regarding the amount and type of 

919 land converted to corn or soybeans as a result of biofuel demand. For example, if 

920 the USDA soybean acreage projections hold and additional soybean acreage is not 

921 required to meet biodiesel demand, then the impact of soybeans for biodiesel on 

922 soil quality is likely to be relatively minimal. However, if soybean acreage 

923 increases beyond current levels, determining how much land is being converted, 

924 the previous crop-type of that land, and its geographical location will be necessary 

925 to assess the impact of this increase on soil quality. More studies on land use/land 

926 cover changes as a result of ethanol and biodiesel demand are needed.

 927 

928 • Secondarily, uncertainties regarding the effect on soil quality are caused by lack 

929 of detailed land management data. For example, more frequent and detailed 
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930 data—including geographical location—on tillage practices employed would 

931 substantially reduce uncertainties surrounding the soil quality response of 

932 producing biofuels. 

933 

934  The key uncertainties with respect to air quality impacts of increased corn and 

935 soybean production are similar to water quality with respect to fertilizer and 

936 pesticide use and application. In addition, NOx emission rates from fertilized soil 

937 are highly uncertain and variable as they rely on microbial conversion of fertilizer 

938 to nitrate which in turn is influenced by environmental conditions. The extent to 

939 which cover crops and tillage practices are employed, both of which can reduce 

940 fugitive dust emissions, are also highly uncertain. For corn stover, there are a 

941 range of assumptions regarding cropping practices, harvest techniques, and farm 

942 inputs that require more study. 

943 

944  Ecosystem health and biodiversity, including fish and wildlife, are highly 

945 impacted by uncertain environmental factors such as nutrient and sediment runoff. 

946 Nutrient loadings from row crop production into surface waters depend on a 

947 variety of factors, including variations due to weather and are therefore widely 

948 variable (Powers, 2007). Regardless, the ability to reduce chemical exposure of 

949 biota will be beneficial to the ecosystem and local biodiversity. In addition to 

950 resolving uncertainties about those factors, more studies are needed on landscape951 level associations between corn and soybean production and terrestrial and 

952 aquatic biodiversity, as well as biodiversity-related services such as pollination 

953 and natural pest control. 

954 

955  There is substantial uncertainty regarding the impacts of climate change on 

956 regional precipitation patterns and temperatures, which could significantly change 

957 water demand and availability, crop yield, runoff, and soil loss. 

958 

959 3.3 Perennial Grasses

960 3.3.1 Introduction 

961 Perennial grasses are herbaceous plants that grow in successive years from the same root 

962 system. They lack the sugar and starch content to be converted directly into ethanol using 

963 conventional methods, but can be converted using cellulosic conversion technologies. While 

964 cultivation of perennial grasses has potential environmental advantages over traditional row 

965 crops such as corn and soybeans, major technological challenges exist for the development of 

966 these more advanced biofuel conversion technologies. Currently, no commercial-scale facilities 

967 for converting perennial grasses to cellulosic ethanol are operating in the U.S.; however, six 

968 switchgrass cellulosic ethanol production facilities are under development (RFA, 2010). 

969 The predominant perennial grasses for biofuels are likely to be monocultures of 

970 switchgrass (Panicum virgatum) or Giant Miscanthus (Miscanthus x giganteus), hereafter 

971 referred to as Miscanthus. Research suggests that an aggressive genetics program to create fast972 growing strains could increase production of both feedstocks dramatically over current 

973 production levels (Vogel and Masters, 1998). The research community is also exploring mixtures 
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974 of native grassland species—referred to as low-input high-diversity (LIHD) mixtures—as a 

975 feedstock (see text box on next page). Compared to their constituent monoculture perennial 

976 grasses, LIHD mixtures have often demonstrated higher bioenergy yields (i.e., gallons of biofuel 

977 produced per unit of land), and a greater ability to grow in infertile soils, although much less is 

978 known about their commercial potential (Tilman and Lehman, 2006). Most research and 

979 development has been conducted on monocultures of switchgrass and Miscanthus, therefore, 

980 these species are the focus of this section.

981 Switchgrass, a native plant of North America, has historically been grown in the U.S. as 

982 forage for grazing livestock (Parrish and Fike, 2005). Recently, it has entered breeding programs 

983 and agronomic testing as a biofuel feedstock. Miscanthus, which is native to Asia, has been 

984 developed and tested as a biofuel feedstock largely in Europe. Considerable genetic variation in 

985 both these species has yet to be explored to optimize feedstock production and biofuel refining 

986 (Keshwani and Cheng, 2009), but promising traits, including low lignin and ash content, and late 

987 or absent flowering periods (Jakob et al., 2009), indicate ample potential for high crop yields and 

988 efficient conversion to ethanol (Jakob et al., 2009). While standard irrigation, fertilizer, and 

989 pesticide use practices have yet to be developed, recent small-scale farming and larger-scale 

990 studies, such as those conducted by the U.S. Department of Energy’s Regional Biomass Energy 

991 Feedstock Partnership, continue to inform estimates of biofuel perennial grass cultivation and 

992 resource requirements (Parrish and Fike, 2005). Farm-scale studies have demonstrated that 

993 ethanol yield from switchgrass ranges from approximately 240-370 gallons per acre compared to 

994 an average of 330 gallons per acre for corn grain (Schmer et al., 2008). 

995 EISA and Section 211(o) of the Clean Air Act limit land conversion for biofuels to 

996 existing agricultural land cleared or cultivated prior to Dec. 19, 2007, or land that was non997 forested and actively managed or fallow on Dec. 19, 2007 (Clean Air Act, Section 211[o]). As of 

998 November 2009, approximately 28 million of the 31.2 million CRP acres were vegetated with 

999 mixtures of native or introduced grasses for a variety of environmental purposes, including 

1000 wildlife habitat, erosion control, and water quality. Economic modeling of global bioenergy 

1001 markets (POLYSYS) estimates that approximately 8-13 million acres of CRP land and 10-23 

1002 million acres of agricultural cropland in the U.S. could possibly (but not necessarily likely) be 

1003 converted to switchgrass production, depending on economic factors (Walsh et al., 2003). The 

1004 gross impact on CRP land already growing switchgrass would be minimal, and the estimated 

1005 combined conversion of “idle” and “pasture” lands to switchgrass production could be between 

1006 0.78 and 5.58 million acres (Walsh et al., 2003). Comparable quantitative information is not 

1007 available for Miscanthus, however, high biomass yields on areas with poor soil quality in 

1008 southern Illinois demonstrate the potential for Miscanthus on low fertility lands (Pyter et al., 

1009 2004). In addition to CRP land, abandoned cropland is hypothetically available for perennial 

1010 grass cultivation. Assuming suitable technology and infrastructure exists, an estimated 25 billion 

1011 gallons of ethanol could potentially be produced annually if switchgrass is grown on the 

1012 approximately 146 million acres of abandoned agricultural land in the U.S., as long as these 

1013 lands do not fall under restrictions described in Section 211(o) of the Clean Air Act (U.S. EPA, 

1014 2010b, Chapter 6). 

1015 

1016 
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1017 Native Grasslands as a Biofuel Feedstock 

1018 

1019 Recent research has suggested using mixtures of native perennials as a feedstock on marginal or infertile 

1020 lands (Tilman et al., 2006; Tilman et. al, 2009; Campbell et al., 2008; Weigelt et al., 2009). This practice 

1021 is limited by several technological and management hurdles, yet also enjoys many environmental benefits 

1022 not found to the same degree in other feedstocks discussed in this report. Termed “low-input high1023 diversity” (LIHD) mixtures, they are essentially comprised of several plant species that perform different 

1024 functions within the community (e.g., high root mass to prevent soil erosion, nitrogen fixation to reduce 

1025 fertilizer inputs) potentially at different times (e.g. spring versus fall) or the same function in a different 

1026 manner (e.g., root growth and soil carbon sequestration at shallow versus deeper soil depths). LIHD 

1027 mixtures, by definition, have more plant biodiversity than other monoculture-based feedstocks. This 

1028 higher plant biodiversity is often associated with a variety of benefits, including higher stability of 

1029 production, higher quality of habitat for wildlife, lower potential for invasion of the community, reduced 

1030 need for chemical inputs (fertilizers, pesticides), and reduced potential for plant disease and crop losses 

1031 (Fargione et al., 2009; Hooper et al., 2005; Loreau et al., 2002; Reiss et al., 2009). When systems are 

1032 viewed as a composite of many co-occurring processes (e.g. primary production, soil stabilization, and 

1033 decomposition), polycultures sustain higher levels of multiple processes, sometimes termed “ecosystem 

1034 multifunctionality” (Hector and Bagchi, 2007; Zavaleta, 2010). Diverse mixtures also often produce more 

1035 biomass than their average constituent species grown in monoculture; however, the productivity of the 

1036 most productive constituent species is in many cases similar to that of the mixture (Cardinale et al., 2006; 

1037 Loreau et al., 2002; Cardinale, 2007). Although it seems likely that highly productive feedstocks (e.g., 

1038 switchgrass and Miscanthus) managed for maximum production will produce more biomass for biofuel 

1039 production than LIHD mixtures, there are no direct field-scale comparisons between LIHD and other 

1040 feedstocks with which to evaluate this assumption. The only comparison to date found that switchgrass 

1041 grown on productive lands across the Midwestern corn belt (Nebraska, South Dakota, North Dakota) out1042 produced LIHD grown on unproductive land in Minnesota (Schmer et al., 2008). However, monoculture 

1043 crops are expected to require more active management (e.g., to prevent losses from pests) than 

1044 polycultures such as LIHD (Hill et al., 2006; Tilman et al., 2009; Weigelt et al. 2009). Production of a 

1045 feedstock composed of a mixture of species will likely face greater technological and management 

1046 hurdles than production of single-species feedstocks. For example, a mixture of species, having variable 

1047 tissue densities and arrangements in the cropping system, may be more difficult to harvest, transport, and 

1048 process into biofuel than a relatively uniform feedstock grown from a single species. Much more research 

1049 is needed in this area to determine the potential role of LIHD as a biofuel feedstock on marginal or 

1050 infertile lands.

1051 3.3.1.1 Current and Projected Cultivation

1052 Perennial grasses could thrive across many regions of the contiguous U.S. (see 

1053 Figure 3-5). Since many of these species, including switchgrass, have historically dominated 

1054 much of the Midwestern landscape, they are well suited to grow over much of the agricultural 

1055 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. 
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Table 3-3: Comparison of Agricultural Intensity Metrics for 

Perennial Grass and Conventional Crops

Metric Reduction Relative to Corn-Wheat-Soybean Average

Erosion 125 fold

Fertilizer 1.1 fold

Herbicide 6.8 fold

Insecticide 9.4 fold

Fungicide 3.9 fold

1078 Source: Ranney and Mann, 1994.

 1079 

1080 3.3.2.1 Nutrient Loading

1081 Nutrients—Surface Water Impacts 

1082 Relative to annual crops, such as corn and soybeans, production of switchgrass and 

1083 Miscanthus requires less fertilizer and reduces nutrient runoff. Switchgrass is inherently efficient 

1084 in its nitrogen use, as well as its use of potassium and phosphorus (Parrish and Fike, 2005). 

1085 Switchgrass and Miscanthus are both nutrient-efficient because they store carbohydrates and 

1086 nutrients in their roots at the end of the growing season (Beale and Long, 1997; Beaty et al., 

1087 1978; Simpson et al., 2008). Therefore, the practice of harvesting the above-ground biomass 

1088 reduces the need for fertilization in subsequent growing seasons. A recent study reported that 

1089 Miscanthus can fix atmospheric nitrogen, which could be a large benefit to its use as a feedstock 

1090 (Davis et al., 2010). Studies have shown no response in Miscanthus growth to nitrogen additions, 

1091 suggesting these fertilizers are not needed in its production (Clifton-Brown et al., 2007; 

1092 Danalatos et al., 2007). In contrast, switchgrass yields increase with nitrogen fertilization, with 

1093 recommended application rates for switchgrass grown for biofuels ranging from 41 to 120 kg 

1094 nitrogen/ha/year (37 to 107 lbs nitrogen/acre/year), varying by region (McLaughlin and Kszos, 

1095 2005). Data for switchgrass and Miscanthus have been generally based on experimental plots, 

1096 and management and yields may differ at the farm-scale. However, if these lower nitrogen 

1097 fertilization rates hold, average nitrogen losses to surface waters should be lower relative to the 

1098 production of corn starch ethanol (ORNL, n.d.). 

1099 Nutrients— Coastal Waters Impacts 

1100 As mentioned above, switchgrass and Miscanthus cropping systems are expected to 

1101 require fewer fertilizer additions compared to traditional row crops, and have been shown to 

1102 reduce chemical oxygen demand in runoff when used as filter strips (Keshwani and Cheng, 

1103 2009). This will minimize their impact on the hypoxic zones of U.S. coastal waters.

1104 3.3.2.2 Sediment

1105 Switchgrass and other perennial grasses have been used as an erosion control 

1106 management practice to reduce sediment loads from row crops (Hill, 2007; McLaughlin and 

1107 Walsh, 1998; U.S. EPA, 2009a). Perennial grasses have been shown to reduce erosion 125-fold 

1108 when compared to an average of corn, wheat, and soybeans (see Table 3-3). Therefore, assuming 
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1109 good agricultural practices, switchgrass production is not expected to increase sediment loads to 

1110 surface waters.

1111 3.3.2.3 Pesticides

1112 Perennial grasses, such as switchgrass (native to the U.S.), are generally less susceptible 

1113 to pests than traditional row crops (Oyediran et al., 2004; Keshwani and Cheng, 2009). A 2004 

1114 controlled greenhouse study found that recovery of a dominant pest (western corn rootworm) 

1115 was 0.2 to 82 times more likely from corn than from 20 other grass species native to the Midwest 

1116 (Oyediran et al., 2004). However, most species are likely to be more susceptible to pests when 

1117 grown in monocultures as compared to polycultures. The lack of commercial perennial grass 

1118 production as biofuel feedstock therefore makes it difficult to predict how much pesticide would 

1119 be needed for this application and what the environmental impacts would be. In non-commercial 

1120 production, pesticide releases from perennial grass plantings are much less than from corn or 

1121 soybeans (Hill et al., 2006). Switchgrass plantings use approximately 90 percent less pesticide 

1122 than row crops (Keshwani and Cheng, 2009). However, herbicides are used initially to establish 

1123 and maintain switchgrass plantings for harvest. Switchgrass filter strips have been shown to 

1124 reduce dissolved atrazine and metachlor concentrations in runoff (Keshwani and Cheng, 2009). 

1125 Information relevant to potential pesticide use for Miscanthus in the U.S. is generally lacking; 

1126 however, researchers in Europe have reported that pesticide requirements are low compared to 

1127 row crops (Lewandowski et al., 2000). 

1128 Of particular concern is how cellulosic feedstock production may impact the spread of 

1129 the western corn rootworm (WCR), whose soil-borne larval stage is estimated to be responsible 

1130 for more than $1 billion in annual losses in the U.S. Corn Belt (Rice, 2003). Recent research 

1131 reported that WCR is able to use Miscanthus and several North American grasses as a host, 

1132 though not as effectively as corn (Oyediran et al., 2004; Spencer and Raghu, 2009). Similar 

1133 information on WCR use of switchgrass as a host is not available, though perennial grasses 

1134 generally are more resistant to pests than corn (Lewandowski et al., 2003; Oyediran et al., 2004). 

1135 3.3.2.4 Pathogens and Biological Contaminants 

1136 The reviewed literature does not directly discuss the effect of perennial grass plantings on 

1137 pathogens in runoff or the potential for pathogen loads associated with perennial grass 

1138 management (i.e., from manure used as fertilizer). Since perennial grasses require fewer inputs 

1139 and take up more impurities from surface water, fewer contaminants are expected from its 

1140 growth compared to row crops. 

1141 3.3.3 Water Quantity

1142 3.3.3.1 Water Use

1143 Switchgrass is an important native grass in prairies across North America and does not 

1144 require additional irrigation. As such, studies that calculate water use for ethanol produced from 

1145 switchgrass often assume that the feedstock is rain-fed, requiring no irrigation, and is capable of 

1146 tolerating moisture deficits (Dominguez-Faus et al., 2009; Wu et al., 2009). Nonetheless, 

1147 greenhouse and field studies indicate switchgrass significantly increases biomass production with 
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1148 access to ample water (Barney et al., 2009; Heaton et al., 2004). Thus, farmers may irrigate crops 

1149 to maximize biomass production, though likely at much lower levels than required for row crops. 

1150 Two major subtypes of switchgrass that differ in their water use characteristics have been 

1151 identified in the wild: an upland and a lowland type. The upland type tends to tolerate dry 

1152 conditions, though there is considerable variation in growth characteristics based on 

1153 environment, which is likely due to limited crop selection and improvement. The lowland type 

1154 requires more water (Parrish and Fike, 2005). Switchgrass farmers may be able to minimize 

1155 water use by cultivating the upland type of switchgrass.

1156 Miscanthus appears to be at least as efficient at using water for growth as corn and likely 

1157 more so (Beale et al., 1999), though considerable variation exists in the productivity of 

1158 Miscanthus based on the identity of the cultivar, where it is grown, and the irrigation regime 

1159 (Clifton-Brown et al., 2001; Richter et al., 2008). Published field studies testing Miscanthus in 

1160 the U.S. are limited, however, and water use practices have not been established. 

1161 3.3.3.2 Water Availability 

1162 Depending on where perennial grasses are grown, whether irrigation is required, and 

1163 what crops they replace (if any), perennial grass production could improve water availability. 

1164 Ground water availability, in particular, could be improved in places like Nebraska, where 

1165 aquifers provide 85 percent of the water to agriculture (Kenny et al., 2009), if perennial grasses 

1166 replace more water-dependent crops (NASS, 2009). Water availability will be minimally 

1167 affected in areas requiring little or no irrigation.

1168 3.3.4 Soil Quality

1169 3.3.4.1 Soil Erosion 

1170 Both switchgrass and Miscanthus have extensive root systems that prevent the erosion of 

1171 soil and, unlike corn and soybeans, these perennial grasses are not planted on an annual basis, 

1172 reducing the frequency of soil disturbance. Currently, switchgrass can be planted in conventional 

1173 tillage and no-till systems, whereas Miscanthus is planted in tilled fields (Heaton et al., 2008; 

1174 Parrish and Fike, 2005). This one-time tillage can increase erosion risk, particularly in 

1175 Miscanthus where plant growth is slow the first year following planting and does not provide 

1176 substantial ground cover (Lewandowski et al., 2000). In subsequent years, however, Miscanthus

1177 stands generally have high yields and dense root mats (Heaton et al., 2008; Lewandowski et al., 

1178 2000), and likely provide substantial erosion control benefits relative to annually planted crops. 

1179 Erosion control by switchgrass has received more study than that of Miscanthus. Switchgrass has 

1180 been extensively planted on CRP acreage for erosion reduction, and planting switchgrass in 

1181 riparian zone grass barriers and vegetation strips has been shown to substantially reduce runoff, 

1182 sedimentation, and nutrient loss (Blanco-Canqui et al., 2004). 

1183 3.3.4.2 Soil Organic Matter

1184 In general, soil organic matter increases more under perennial species than annual species 

1185 because of the continuous accumulation of plant material (Sartori et al., 2006). Soil carbon is a 

1186 primary constituent of soil organic matter. The production of both switchgrass and Miscanthus
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1187 can increase soil carbon, but these organic matter benefits are likely to depend on the particular 

1188 land use replaced and specific management practices. Where perennials are planted on degraded 

1189 soils with low organic matter content, soil erosion can be reduced and carbon stocks restored 

1190 (Clifton-Brown et al., 2007; McLaughlin and Kszos, 2005). For example, on such a soil, 

1191 switchgrass has been predicted to increase soil carbon by approximately 12 percent following 

1192 one decade of production and harvesting (Garten and Wullschleger, 2000). If perennial grasses 

1193 replace annual crops, perennials will likely increase soil organic matter, though direct 

1194 comparisons are limited (Bransby et al., 1998; Schneckenberger and Kuzyakov, 2007). In one 

1195 such study, relative to reported values for corn, soil carbon increased under Miscanthus

1196 cultivation when its above-ground vegetation was harvested annually; however, this result varied 

1197 according to soil type, with carbon increasing in a loamy soil but not in a sandier textured soil 

1198 (Schneckenberger and Kuzyakov, 2007). Soil organic matter accumulation under these 

1199 perennials depends, in part, on harvest frequency, and, in the case of switchgrass, on the potential 

1200 application of nitrogen fertilizer (Lee et al., 2007b). On the other hand, the effect on soil organic 

1201 matter of preparing previously undisturbed land for these biofuel feedstocks has received little 

1202 attention to date. Estimates of carbon loss following conventional tilling of undisturbed soils 

1203 range from 20 to 40 percent (Davidson and Ackerman, 1993). The amount of time needed for 

1204 these perennials to restore soil carbon lost following site preparation is uncertain. 

1205 3.3.5 Air Quality

1206 As mentioned earlier, little is known overall about the extent to which fertilizer, 

1207 herbicides, and pesticides will be used to increase perennial grass production. Grasses require 

1208 significantly less nitrogen fertilizer than corn or soybean, and studies indicate that NOx emissions 

1209 should decrease when switchgrass is used as a feedstock (Wu and Wang, 2006). However, 

1210 switchgrass is not currently grown on large scales under typical farm conditions. Nitrogen 

1211 fertilizer rates are based on field trials, which are not extensive (Wu and Wang, 2006) and may 

1212 differ from on-farm conditions (Hill et al., 2009). Similarly, switchgrass has been shown to 

1213 require lower amounts of phosphorus (P2O5) fertilizer, which translates to lower SO2 emissions

1214 (Wu and Wang, 2006) 

1215 As described earlier in Section 3.3.2.3, perennial grasses are expected to require less 

1216 pesticide and herbicide than row crops (except when initially establishing perennial grass 

1217 plantings); however, the lack of experience with commercial perennial grass production as a 

1218 biofuel feedstock precludes firm conclusions about potential air quality impacts.

1219 As with corn and soybeans, harvesting of switchgrass will involve use of farm 

1220 equipment, and thus is expected to generate NOx and PM emissions. However, VOCs and NOx

1221 and PM emissions associated with switchgrass harvesting have been found to be much lower

1222 than those associated with corn harvesting (Hong and Wang, 2009). Decreases in VOCs, CO, 

1223 NOx, PM10, PM2.5, and SO2 emissions associated with switchgrass production as compared to 

1224 corn or soybean have been reported (Wu and Wang, 2006; Hess et al., 2009). 
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1225 3.3.6 Ecosystem Impacts

1226 3.3.6.1 Biodiversity

1227 Models indicate that a greater diversity of birds are supported by switchgrass than by row 

1228 crops (corn or soy), though some non-priority species such as horned lark (Eremophila alpestris)

1229 and killdeer (Charadrius vociferous) may decline (Murray and Best, 2003; Murray et al., 2003). 

1230 One study found that perennial grass crops can provide substantially improved habitat for many 

1231 forms of native wildlife—including ground flora, small mammals, and bird species—due to the 

1232 low intensity of the agricultural management system (Semere and Slater, 2006). Increases in 

1233 avian diversity are insensitive to whether switchgrass is strip harvested or completely harvested

1234 (Murray and Best, 2003). However, field studies have shown that different species prefer habitats 

1235 under different management regimes, suggesting that switchgrass cultivation under a mosaic of 

1236 field ages and management regimes will maximize total avian diversity over a large landscape

1237 (Murray and Best, 2003; Roth et al., 2005). Research from Nebraska and Iowa shows that 

1238 populations of white-tailed deer are not likely to decline following conversion of land from corn 

1239 to native grassland (i.e., dominated by switchgrass), but may experience contraction of home 

1240 ranges to areas near row crops, increasing crop losses and the potential for disease transmission

1241 among wildlife (Walter et al., 2009). Though similar studies for Miscanthus in the U.S. are 

1242 lacking, research from the United Kingdom shows that non-crop plants from a wide range of 

1243 families (Poaceae, Asteraceae, and Polygonaceae) coexist within young Miscanthus cropping 

1244 systems due to a lack of herbicide applications, and support a greater diversity of bird 

1245 populations than annual row crops (especially of passerines, game birds, and thrushes) (Bellamy 

1246 et al., 2009). These effects are likely to be transient as fields mature and crop height and 

1247 coverage become more homogeneous (Bellamy et al., 2009; Fargione et al., 2009). Similar 

1248 patterns are likely for the U.S. Use of native mixtures of perennial grasses can restore some 

1249 native biodiversity (Tilman et al., 2006). 

1250 3.3.6.2 Invasive Plants 

1251 Grasses are successful at reproducing, dispersing, and growing under diverse 

1252 environmental conditions. This helps explain their dominance across many areas of the globe, 

1253 and contributes to their potential risk as agricultural weeds and invasive plants. The risk that 

1254 switchgrass or Miscanthus will become an agricultural weed or invasive plant depends on their 

1255 specific biology and their interaction with the environments in which they are grown. One study 

1256 noted that well-managed biofuel feedstock production must not only prevent feedstock crops 

1257 from invading local habitat, but also prevent the crops from genetically invading native species 

1258 (Firbank, 2007). 

1259 Switchgrass produces large amounts of seed, a trait that correlates with the ability to 

1260 spread, though it remains unclear how much and how far switchgrass seed can disperse. 

1261 Switchgrass is being bred for vegetative reproduction, tolerance to low fertility soils, and the 

1262 ability to grow in dense stands (Parrish and Fike, 2005), all of which could increase invasive 

1263 potential. On the other hand, breeding for traits like sterility can be utilized to reduce the risk of 

1264 escape and likelihood of negative impacts. For example, hybrid Miscanthus cultivars have been 

1265 bred to produce almost no viable seed. 
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1266 The location where a feedstock is grown and the interaction between the feedstock and 

1267 the local environment will be important for determining its invasion potential. Using species 

1268 native to the area they are cultivated minimizes the risk of invasion into natural areas. 

1269 Switchgrass is native east of the Rocky Mountains, although a variety could be bred or 

1270 engineered to be substantially different from local populations. Switchgrass in any form is not 

1271 native west of the Rockies. One risk assessment of introducing switchgrass to California 

1272 indicated that it could become invasive relatively easily (Barney and DiTomaso, 2008). The 

1273 potential for switchgrass to become a weed of other agricultural crops, even within its native 

1274 range, is not known. 

1275 Unlike switchgrass, Miscanthus x giganteus (the variety of Miscanthus that has been 

1276 tested in Europe as a biofuel feedstock) is not native anywhere in the U.S. Little information 

1277 exists about the ability of M. x giganteus to disperse from cultivation and persist as a weed or 

1278 invade natural areas. One risk assessment recommended no restrictions on planting in the U.S. 

1279 because the plant produces no living seeds and is therefore unlikely to spread easily (Barney and 

1280 DiTomaso, 2008). A different study, however, noted that Miscanthus can spread vegetatively and 

1281 could undergo genetic changes to produce seeds once more—making it potentially invasive

1282 (Raghu et al., 2006). Miscanthus sinensis has been grown in the U.S. for landscaping and 

1283 horticultural purposes. Herbarium specimens and field observations indicate that it can disperse 

1284 live seeds and persist in areas beyond where it was originally planted. Miscanthus sinensis, a 

1285 species related to Giant Miscanthus, has been grown in the U.S. for landscaping and horticultural 

1286 purposes, and is also being developed as a biofuel feedstock. Herbarium specimens and field 

1287 observations indicate that it can disperse live seeds and persist in areas beyond where it was 

1288 originally planted, including a variety of habitats like pasture, clearcut forests, and residential 

1289 areas (Quinn et al., 2010). A recent study found that Miscanthus sinensis spreads quickly enough 

1290 to be labeled invasive (Quinn and Stewart, 2010). Some other grass species that have been 

1291 considered for use as biofuel currently invade wetlands, including giant reed (Arundo donax) 

1292 (Bell, 1997) and reed canary grass (Phalaris arundinacea) (Lavergne and Molofsky, 2004). 

1293 While feedstock cultivation poses the greatest risk for invasive impacts, reproductive 

1294 parts from feedstocks could also be dispersed during transport from the field to storage or 

1295 ethanol-processing facilities. Roads, railroads, and waterways can act as man-made corridors for 

1296 non-native and invasive plants. Harvested switchgrass possesses living seed and Miscanthus can 

1297 reproduce vegetatively from plant cuttings, both of which may be dispersed during feedstock 

1298 transport. 

1299 One mitigation option for reducing the potentially negative environmental impacts from 

1300 perennial grass production is avoiding cultivation of feedstocks with a history of invasiveness, 

1301 especially in places that are climatically similar to where invasion has already occurred. Another 

1302 option is to breed feedstocks to limit their dispersal into other fields or natural areas (e.g., the 

1303 sterile Miscanthus x giganteus). For instance, sterile, seedless switchgrass cultivars would be less 

1304 likely to become invasive than current, seed-bearing cultivars. Often, higher reproduction 

1305 correlates with lower biomass, so aggressive breeding programs to increase biomass and 

1306 decrease seed production could produce multiple benefits. 

1307 Another strategy for managing potential invasiveness is cleaning harvesting machinery 

1308 and vehicles used to transport harvested feedstock, which would help to decrease unintended 
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1309 dispersal. Though prevention is most desirable, early detection and rapid response mechanisms 

1310 could also be put into place to eradicate persistent populations of feedstock species as they arise, 

1311 but before they have the chance to spread widely (DiTomaso et al., 2010). Such early detection 

1312 and rapid response mechanisms might involve local monitoring networks and suggested 

1313 mechanical and chemical control strategies (timing and application rate of herbicides, for 

1314 example) devised by local agricultural extension scientists for specific feedstocks.

1315 3.3.7 Assessment

1316 Perennial grasses are likely to require less pesticide, fertilizer, and water than traditional 

1317 row crops used for biofuel production (Downing et al., 1995). The benefits of perennial grasses 

1318 as a feedstock include reduced soil erosion, enhanced soil structure and carbon sequestration, 

1319 reduced nitrogen loading and sedimentation to waterways, reduced hypoxia in coastal areas, and 

1320 greater support for populations of non-crop plants as well as animals and soil biota (Fargione et 

1321 al., 2009; Hill, 2007; Williams et al., 2009). Use of perennial grasses as a biofuel feedstock 

1322 carries many advantages to ecosystem services and to biodiversity relative to traditional row 

1323 crops. The magnitude of these advantages depends on resolving some uncertainties and also on 

1324 whether perennial grasses are replacing CRP land, row crop farmland, or other lands such as 

1325 pasture land, and whether they are grown in a monoculture or in a mixture of species. The 

1326 maintenance of landscape-level biodiversity (e.g., including non-cultivated, protected areas

1327 nearby) will depend on the spatial arrangement of reserves promoting connectivity and 

1328 population persistence, local management practices, and potential for biofuel crops and their 

1329 pests to spread beyond managed boundaries. 

1330 3.3.7.1 Key Uncertainties and Unknowns

1331 • Because no commercial-scale facilities exist for converting perennial grasses to 

1332 cellulosic ethanol, many uncertainties remain about how growing perennial 

1333 grasses as a feedstock will affect environmental conditions when grown at 

1334 commercial scales. This holds for all endpoints documented in this report (soil 

1335 carbon, leaching, etc.) and highlights the need for large-scale studies comparing 

1336 perennial grass cultivated under a variety of management regimes with row crops 

1337 and other feedstocks. 

 1338 

1339 • Most existing literature on switchgrass examines the plant’s rangeland and 

1340 ecological purposes; this literature might not be completely applicable to 

1341 switchgrass used as a biofuel feedstock. 

 1342 

1343 • Much genetic potential for both Miscanthus and switchgrass remains to be 

1344 explored for increasing their feasibility as feedstocks. If researchers are able to 

1345 develop novel cultivars of these plants with significantly improved yields, there 

1346 may be less potential for environmental damage from Miscanthus and switchgrass 

1347 production. 

 1348 

1349 • Little is known about usage of fertilizer and pesticides for increasing perennial 

1350 grass production. The usage of precision management strategies (e.g., minimal 

1351 fertilization, irrigation, and pest management at specific times) may potentially 
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1352 increase productivity without deleterious ecological impacts. Depending on where 

1353 these crops are grown and what crops or other land use they are replacing, they 

1354 may improve water quality relative to the previous land use.

 1355 

1356 • The water requirements of different grass species in different areas of the country 

1357 are not documented, and the use and preferred method of irrigation remains to be 

1358 determined.

 1359 

1360 • The role of nitrogen fixation in explaining the productivity of Miscanthus requires 

1361 further study and may have large ramifications on the potential use of Miscanthus 

1362 as a feedstock.

 1363 

1364 • The potential invasiveness of switchgrass in the western U.S. and Miscanthus

1365 across all the entire U.S. is relatively unknown. Studies to evaluate feedstocks for 

1366 the biological characteristics associated invasiveness, including rate of seed 

1367 production, rate and maximum distance of dispersal from field-scale plots, modes 

1368 of dispersal (e.g., wind, water, bird), rate of hybridization with already invasive 

1369 relatives, resistance to chemical or mechanical control, etc., are crucial for 

1370 anticipating and preventing negative impacts and for determining which 

1371 alternative feedstocks might pose lower risks. 

 1372 

1373 • It remains uncertain whether the continual removal of above-ground biomass will 

1374 deplete soil nutrients over the long term, particularly on marginal soils. On these 

1375 soils, it may be particularly critical to harvest after translocation of nutrients back 

1376 into the root systems.

 1377 

1378 • More landscape-level research is needed to understand how the distribution of 

1379 multiple land use systems across a large landscape (e.g., row crops interspersed 

1380 with perennial biofuel grasses and native habitat) will affect local and regional 

1381 biodiversity. 

 1382 

3.4

1384 3.4.1 Introduction

1383 Woody Biomass

1385 Woody biomass includes trees (e.g., removed or “thinned” from forests to reduce fire 

1386 hazard or stimulate growth of remaining stands); forest residues (e.g., limbs, tree tops, and other 

1387 materials generally left on-site after logging); short-rotation woody crops (SRWCs; i.e., fast1388 growing tree species cultivated in plantation-like settings) and milling residues. Woody biomass

1389 is an attractive energy source because of its widespread availability and capacity to store carbon. 

1390 However, to date woody biomass has been of limited use for energy production, with the 

1391 exception of pulp and saw mill residues burned to produce heat, steam, and electricity. Woody 

1392 biomass has been of particular interest as a biofuel feedstock because some forests might benefit 

1393 from thinning and/or residue removal: removing forest residues from forests could reduce the 

1394 threat of catastrophic wildfires, at least in some ecosystems, while providing a feedstock for 

1395 energy production (Gorte, 2009). No commercial-scale biofuel plants using woody biomass as a 
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1396 feedstock are yet in operation, but demonstration and development facilities exist, and woody 

1397 biomass is projected to be a future source of cellulosic biofuels. 

1398 The U.S. has substantial domestic capacity for producing fuel from woody biomass. 

1399 Estimates of the amount of woody biomass available for biofuel production differ widely and 

1400 vary by price paid per ton of feedstock. EPA’s RFS2 RIA notes that, at $70 per ton, 40 to 118 

1401 million dry tons of woody biomass may be available for biofuel production in 2022 (U.S. EPA, 

1402 2010b, p. 49). At a currently demonstrated conversion rate of 80 gallons of ethanol per dry ton, 

1403 up to 9.4 billion gallons of ethanol could be produced from 118 million dry tons (Foust et al., 

1404 2009). Additionally, the conversion rate of biomass to ethanol will likely improve in the future. 

1405 Under the RFS2 requirements, not all woody biomass would be available. The RFS2 

1406 limits the origin of woody biomass to “planted trees and tree residue from actively managed tree 

1407 plantations on non-federal land cleared at any time prior to December 19, 2007” (U.S. EPA, 

1408 2010h, p. 56). Both forest harvesting residues and thinning operations are expected to be the 

1409 predominant sources of woody biomass for future biofuel use, but SRWCs may be important as 

1410 well at higher feedstock prices (Perlack et al., 2005; U.S. EPA, 2010b, pp. 38-49; White, 2010). 

1411 In the following sections, the potential impacts of harvest residues, thinning, and SRWCs are 

1412 discussed in more detail. For comparison purposes, the environmental impacts of SRWCs are 

1413 considered in relationship to annual row crops. However, economic analyses suggest that the 

1414 most likely sources of land for SRWC plantations are CRP or fallow agricultural lands, rather 

1415 than prime agricultural acres or grasslands; therefore, SRWCs are generally unlikely to replace 

1416 row crops (Volk et al., 2006; Walsh et al., 2003). 

1417 3.4.1.1 Current and Projected Production Areas

1418 The potential sources of woody biomass vary by region of the country, and only SRWC 

1419 plantations are likely to result in land use/land cover changes. Forest harvest residues are 

1420 produced in major forest harvesting areas, predominantly in places such as the upper Lake States, 

1421 the Southeast and the Pacific Northwest (see Figure 3-6). Since these residues will most likely be 

1422 collected as a by-product of harvesting operations, the use of forest harvest residues is unlikely to 

1423 produce land use/land cover changes (Williams et al., 2009). However, a rise in price paid per 

1424 ton for woody biomass may provide an incentive for additional harvesting. Woody biomass from 

1425 forest thinning will also occur in major forest harvesting areas, and potentially in areas of high 

1426 wildfire risk. In contrast, SRWC plantations can have substantial land use/land cover effects.
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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 biomass 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 
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1447 of fertilizer, pesticide use and replanting interval). Table 3-4 shows inputs needed to grow 

1448 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

Metric Reduction Relative to Corn-Wheat-Soybean Average

Erosion 12.5 fold

Fertilizer 2.1 fold

Herbicide 4.4 fold

Insecticide 19 fold

Fungicide 39 fold

1449 Source: Ranney and Mann, 1994.

 1450 

1451 3.4.2.1 Nutrients

1452 The literature is mixed on whether residue removal increases (Kreutzweiser et al., 2008) 

1453 or decreases(Lundborg, 1997) nutrient loads to surface water bodies, including wetlands. The 

1454 impacts of removing tree harvest residues on nutrient loads vary depending on topography 

1455 (slope), soil nutrient content, and the chemistry of the residues themselves (Titus et al., 1997). 

1456 Compared to forest residue removal, moderate forest thinning typically does not increase loss of 

1457 soil nutrients to ground or surface waters (Baeumler and Zech, 1998; Knight et al., 1991). 

1458 Forestry Best Management Practices (BMPs) such as buffer zones (vegetated setbacks 

1459 from water bodies) are used to reduce water quality impacts. Careful planning to minimize the 

1460 construction of roads and stream crossings or the use of portable stream crossing structures can 

1461 help reduce erosion and sedimentation (Aust and Blinn, 2004; Shepard, 2006). Other BMPs 

1462 include: using energy efficient machinery, minimizing traffic in buffer zones and choosing low1463 impact equipment that is of the appropriate size and scope for the site (Phillips et al., 2000). The 

1464 draft 2010 National Report on Sustainable Forests by USDA’s U.S. Forest Service suggests 

1465 widespread adoption of forestry BMPs to protect water resources, although many states failed to 

1466 respond to a request for data (U.S. Forest Service, 2010). If practices are followed, impacts can 

1467 be minimized; outreach, education, and monitoring to ensure implementation and effectiveness 

1468 are ongoing. 

1469 As described above, SRWCs are unlikely to directly replace row crops; however, for 

1470 comparative purposes, it is noted that nutrient losses from SRWCs are in general considerably 

1471 less than in annually cropped systems, depending in part on the harvesting and replanting 

1472 interval. In willow plantations, the recommended fertilization rate is 89 pounds of nitrogen per 

1473 acre (100 kg/hectare) every 3 years, which equates on an annual basis to approximately 22 

1474 percent of the average rate for corn production (Keoleian and Volk, 2005; NASS, 2006). In the 

1475 first year or two following planting, SRWC plantations can exhibit losses of nitrogen at rates 

1476 comparable to conventional grain production, yet following this initial establishment phase, 

1477 nitrogen losses decline to low levels (Aronsson et al., 2000; Goodlass et al., 2007; Randall et al., 

1478 1997). A comparison of nutrient exports from a short-rotation poplar stand and a native forest 

1479 found no difference (Perry et al., 1998), and measurements of nitrogen in ground water and 
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1480 leaching from established willow plantations generally show little eutrophication potential for 

1481 aquatic ecosystems (Keoleian and Volk, 2005). In coppiced systems, where trees are harvested at 

1482 the ground level and re-grow from the stump, the harvesting of the aboveground portion of the 

1483 tree appears to have little impact on nitrogen leaching (Goodlass et al., 2007). Losses can be 

1484 substantially higher when the stand is replanted (Goodlass et al., 2007). Longer rotation lengths 

1485 would likely improve nutrient retention on-site and reduce losses to waterways.

1486 3.4.2.2 Sediment

1487 Forest soils generally exhibit low erosion rates and thus small sediment losses to surface 

1488 waterways (Neary et al., 2009). However, when forests are harvested and the soil prepared for 

1489 the next stand without using BMPs, erosion rates can increase significantly (McBroom et al., 

1490 2008). Harvesting residues left on-site physically shield soil particles from wind and water 

1491 erosion, and promote soil stability through the addition of organic matter. Thus, removal of 

1492 harvest residues is an element of harvest operations that could increase erosion and associated 

1493 sediment loading to surface waters, especially on steeper slopes (Edeso et al., 1999). Thinning 

1494 can also increase erosion and sediment loads to surface waters, depending on the site 

1495 characteristics and the methods used (Cram et al., 2007; U.S. Forest Service, 2005; Whicker et 

1496 al., 2008). Research indicates that proper use of BMPs, such as road design and buffer zones, can 

1497 significantly reduce sediment impacts to surface waters (Aust and Blinn, 2004; Shepard, 2006). 

1498 In addition, erosion rates at harvested sites decline once vegetation re-colonizes the site (Aust et 

1499 al., 1991; Miller et al., 1988). See Section 3.4.4.1 for discussion of impacts of SRWCs on soil 

1500 erosion and sedimentation. 

1501 3.4.2.3 Pesticides

1502 Pesticides might be used with SRWCs; for purposes of comparison, it is noted that the 

1503 amount used would be significantly less than that for corn or soybeans (Ranney and Mann, 

1504 1994). 

1505 3.4.3 Water Quantity

1506 3.4.3.1 Water Use

1507 The utilization of harvest residues from mature stands of trees and thinning does not 

1508 require additional water use at the feedstock production stage.

1509 For the most part, growth of SRWCs will likely occur in areas with high water 

1510 availability, such as the Northeast, Southeast, and Northwest. Because they are usually not 

1511 irrigated, trees require less total water than row crops (Evans and Cohen, 2009). However, they 

1512 can still have a large impact on regional water availability due to their much higher 

1513 evapotranspiration rate. In places where high-intensity tree plantations replace existing 

1514 ecosystems with lower evapotranspiration rates, the potential for increased water consumption is 

1515 significant. A study of southern pine in the Southeast found that an additional 865 gallons of 

1516 water is consumed per gallon of ethanol produced from woody biomass (roughly 1,300 gallons 

1517 of water per gallon of gasoline equivalent), due to land conversion for woody biomass 

1518 production (Evans and Cohen, 2009). Further, in certain locations and in some years, additional 
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1519 irrigation water may be required to maintain high biomass accumulation (Hansen, 1988). 

1520 Precision application systems can reduce the amount of water applied.

1521 3.4.3.2 Water Availability

1522 Use of forest harvest residues and biomass from thinning should have little or no effect 

1523 on water availability at the feedstock production stage. Plantations of SRWCs may reduce runoff 

1524 into streams and rivers compared to traditional row crops like corn and soybeans, potentially 

1525 benefiting water quality (Updegraff et al., 2004). However, some experts warn that reduced 

1526 runoff coupled with high water requirements could reduce or eliminate stream flow (Jackson et 

1527 al., 2005). In places with seasonal flooding, modulation of surface water flow closer to pre1528 agricultural development levels could possibly mitigate flooding (Perry et al., 2001). 

1529 3.4.4 Soil Quality

1530 3.4.4.1 Soil Erosion 

1531 The soil erosion impacts of SRWCs will depend on harvesting and planting frequencies; 

1532 impacts are lower when time between planting intervals is longer. Short-rotation woody crops 

1533 require intensive soil preparation for successful establishment, and it is during this brief 

1534 establishment phase that erosion rates can be a high (Keoleian and Volk, 2005). For example, 

1535 higher sediment losses were observed within the first 3 years of seedling establishment in 

1536 sweetgum (Liquidamber styraciflua) plantations compared to no-till corn or switchgrass 

1537 (Nyakatawa et al., 2006). The slow-developing canopy failed to provide adequate ground cover 

1538 to protect against erosion as a result of rainfall (Nyakatawa et al., 2006). However, in established 

1539 SRWC plantations, soil erosion rates are likely much lower than those of annually harvested row 

1540 crops. The use of a cover crop can also significantly reduce erosion caused by SRWC 

1541 establishment (Nyakatawa et al., 2006), and the soil erosion effects of SRWCs are likely to be 

1542 lower under a coppicing system, which reduces the frequency of soil disturbance by keeping the 

1543 root systems intact. Willows are generally managed by the coppicing system and harvested at 3- 

1544 to 4-year intervals for a total of 7 to 10 harvests (Keoleian and Volk, 2005). This allows 21 to 40 

1545 years between soil disturbances. 

1546 3.4.4.2 Soil Organic Matter

1547 Harvesting of forest residues removes plant material that could otherwise become soil 

1548 organic matter. A review analysis suggested that, on average, a complete, one-time removal of 

1549 forest residues slightly decreases soil organic matter in coniferous forests, but may not affect 

1550 levels in hardwood or mixed stands (Johnson and Curtis, 2001). Leaving logging residues is 

1551 important for soils with low organic matter content, and repeated harvesting of residues in the 

1552 same location could lead to overall declines in soil organic matter (Thiffault et al., 2006). Further 

1553 research is needed to determine the cumulative effect of repeated removals. Thinning of forests 

1554 has been shown to reduce carbon in forest floor layers, but less evidence is available regarding 

1555 its impact on mineral soil organic matter levels (Grady and Hart, 2006; Jandl et al., 2007). The 

1556 effect of thinning over the long-term will depend on both the frequency and intensity of the 

1557 specific thinning operations. 
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1558 Production of SRWCs can add organic matter to the soil, sequestering carbon, but the net 

1559 soil organic matter benefits of these crops depend on land-use change and time between harvests. 

1560 Generally, soil organic matter, including carbon, is initially lost when a forest is planted because 

1561 the amount of organic matter entering the soil from the reestablishing plants is typically small 

1562 and is exceeded by decomposition (Paul et al., 2002). Over time, substantial amounts of organic 

1563 matter accumulate in the trees, the forest floor layer and the soil, greatly exceeding the carbon 

1564 contained in abandoned agricultural systems (Schiffman and Johnson 1989; Huntington 1995; 

1565 Richter et al., 1999). The amount of time it takes for soil carbon to re-accumulate varies. In 

1566 hybrid poplar plantations in Minnesota, it was estimated to take 15 years to meet the carbon 

1567 levels of the agricultural field replaced (Grigal and Berguson, 1998). A review study suggested 

1568 that on average it can take 30 years to exceed those of abandoned agricultural fields; though 

1569 when the forest floor was also considered, carbon accumulation rates were higher, reducing the 

1570 time needed to regain carbon from the initial forest establishment (Paul et al., 2002). Overall, if 

1571 frequently harvested SRWCs replace longer rotation, managed forest lands, then the net effect on 

1572 soil organic matter is likely to be negative; but, if they are grown using longer rotations, 

1573 particularly on degraded former agricultural land, substantial amounts of organic matter are 

1574 likely to added to the soil (Schiffman and Johnson, 1989; Huntington 1995). 

1575 3.4.4.3 Soil Nutrients

1576 Use of harvesting residues removes a potential source of soil nutrients that can be utilized 

1577 by the regenerating forest. Harvesting with residue removal generally leads to declines in soil 

1578 nutrients and forest productivity, but in some cases, it can be sustainable for at least one rotation 

1579 (McLaughlin and Phillips, 2006; Thiffault et al., 2006). The cumulative effects of repeated 

1580 removals from the same site are likely negative, but require further study. Residue removal has 

1581 been suggested as a management technique to reduce nitrogen in forests that receive high 

1582 atmospheric deposition, such as in the northeastern U.S. (Fenn et al., 1998). However, this may 

1583 lead to depletion of calcium and other nutrients critical for plant growth (Federer et al., 1989).

1584 Overall, residue removal may be less problematic on high fertility soils compared to coarser1585 textured, low fertility soils. The risk posed to soil nutrients by thinning is likely to be much 

1586 smaller than that of the removal of harvesting residues (Luiro et al., 2010). 

1587 There is concern that continual harvesting of SRWCs will deplete soil nutrients over the 

1588 long-term (Adegbidi et al., 2001). Commercial fertilizers or organic waste products, such as 

1589 municipal effluent, can be used to offset these losses (Stanton et al., 2002). Nutrient removal 

1590 from such effluents by SRWCs may provide an additional environmental benefit, though it 

1591 remains unclear how much nitrogen, other nutrients, or contaminants might leach from these 

1592 systems if this technique is used. 

1593 3.4.5 Air Quality

1594 Few data are available for evaluating air emissions from SRWCs such as hybrid poplar 

1595 and willow. As with switchgrass, SRWCs require less tillage (reducing fugitive dust emissions) 

1596 and fewer applications of fertilizer (reducing emissions associated with fertilizer production and 

1597 application). However, some species such as poplar and willow that are potential feedstocks for 

1598 either cellulosic ethanol or biodiesel are significant emitters of biogenic VOCs such as isoprene. 

1599 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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1639 3.4.7 Assessment

1640 Current environmental impacts of production and use of woody biomass as a biofuel 

1641 feedstock are negligible, since no large-scale, commercial operations are yet in existence to 

1642 create demand for this feedstock. However, estimates suggest that the potential for biofuels made 

1643 from woody biomass is substantial, with predominant sources coming from forest harvest 

1644 residues, thinning, and SRWCs. Of these, the removal of harvesting residues from logging sites 

1645 is likely to have the most negative impacts on soil and water quality. Complete removal of 

1646 residues poses the risk of increased nutrient and sediment losses to waterways, and decreased 

1647 plant nutrient availability and forest productivity. In comparison, moderate thinning regimes will 

1648 have relatively few impacts on soil and water quality, particularly on stable slopes and finer1649 textured soils.

1650 The environmental effects of SRWCs as a source of woody biomass are more complex, 

1651 since these require a shift in land use/land cover type. In general, SRWCs are expected to result 

1652 in lower nutrient and sediment loads to surface waters relative to that of row crops, especially 

1653 once the canopy is established. Woody biomass species require fewer inputs of fertilizer and 

1654 pesticides, resulting in reduced runoff of these substances into surface and ground water. Woody 

1655 biomass production requires considerable water use, but if undertaken in appropriate regions 

1656 with adequate water supplies, water quality benefits may outweigh possible water availability 

1657 drawbacks. 

1658 3.4.7.1 Key Uncertainties and Unknowns

1659 • Woody biomass is not yet converted to biofuel on a large-scale; this creates 

1660 considerable unknowns and uncertainties when projecting the potential 

1661 environmental effects, both positive and negative, of this feedstock. 

 1662 

1663 • Specific environmental impacts will vary, depending on soil type, soil chemistry, 

1664 topography, climate, and other factors (e.g., the land use SRWCs would replace). 

 1665 

1666 • Lack of information about the amount and relative proportion of woody biomass 

1667 that would come from harvest residues, thinning, and SRWCs to support large1668 scale operations creates substantial uncertainty. The potential effects of harvest 

1669 residues and thinning are easier to assess because a body of literature from other 

1670 forestry applications does exist. Even so, uncertainties arise from variations in the 

1671 percent of residues removed during harvesting and in the degree of thinning, 

1672 which can range from small to large proportions of the existing stand. 

 1673 

1674 • Quantifying impacts of SRWCs to ecosystems and biodiversity will depend on 

1675 knowing where and under what agronomic conditions SRWCs are grown and how 

1676 they are managed. Uncertainty about these factors limits understanding of the 

1677 potential impacts of this feedstock. For example, it is not known whether repeated 

1678 removal of biomass from SRWCs will deplete soil nutrients over the long term, 

1679 particularly on marginal soils.

 1680 
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3.5

1682 3.5.1 Introduction

1681 Algae

1683 Algae are of interest as a biofuel feedstock because of their high oil content, low water 

1684 demand, ability to recycle waste streams from other processes, and ability to grow on marginal 

1685 lands (EPA, 2010b). Algae production demands much less land area per gallon of fuel produced 

1686 compared to most other feedstocks. 

Research and pilot studies have shown that the lipids and carbohydrates in microalgae19

1693 There are many different types of algae, methods to cultivate them, and processes to 

1694 recover oil from them. Algae grown photosynthetically are limited to growth during daylight 

1695 hours and require carbon dioxide. Heterotrophic algae, which do not utilize photosynthesis, can 

1696 be grown continuously in the dark, but require a fixed carbon source such as sugars because they 

1697 cannot use carbon dioxide directly (Day et al., 1991). Cultivation of algae feedstocks can take 

1698 place in photobioreactor facilities with closed-cycle recirculation systems or in open-system1699 style impoundments. Open systems use pumps and paddle wheels to circulate water, algae, and 

1700 nutrients through shallow, uncovered containments of various configurations. Closed systems

1701 employ flat plate and tubular photobioreactors and can be located outdoors or indoors. Variations 

1702 include hybrid (combined open and closed) cultivation and heterotrophic cultivation (which uses 

1703 organic carbon instead of light as an energy source). Different algae cultivation strategies are 

1704 being studied to determine which is most suitable for supporting large-scale biofuel production 

1705 (Chisti, 2007; U.S. EPA, 2010b). 

1687 

1688 can be refined and distilled into a variety of biodiesel- and alcohol-based fuels, including diesel, 

1689 ethanol, methanol, butanol, and gasoline. Algae also have the potential to serve as feedstock for 

1690 other types of fuels, including bio-oil, bio-syngas, and bio-hydrogen. This section focuses on the 

1691 use of algae for biodiesel, because biodiesel is the most likely near-term pathway for algal use as 

1692 biofuel. 

1706 Harvesting requires that the algae be removed, dewatered, and dried. Dewatering is 

1707 usually done mechanically using a screw press, while drying can use solar, drum, freeze, spray, 

1708 or rotary techniques (NRDC, 2009). After harvesting, the biofuel production process begins 

1709 when oil is extracted from the algae through chemical, mechanical, or electrical processes (U.S. 

1710 EPA, 2010b, p. 61). Algal oil can then be refined with the same transesterification process used 

1711 for other biofuel feedstocks such as soybeans. 

1712 While the different methods of algae cultivation and recovery will clearly have very 

1713 different environmental impacts, such as energy consumption and chemical use and disposal, it is 

1714 premature to draw definitive conclusions about these impacts, given the nascent state of 

1715 cultivating algae for biofuel. 

 

19 The term “microalgae” refers to photosynthetic 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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1716 3.5.1.1 Current and Projected Cultivation 

1717 Land use consideration is one of the primary drivers behind interest in algae as a biomass 

1718 feedstock. Relative to other feedstock resources, algal biomass has significantly higher 

1719 productivity per cultivated acre. For example, meeting half the current U.S. transport fuel 

1720 demand with soybean-based biodiesel would require an arable land area in excess of 300 percent 

1721 of the area of all 2007 U.S. cropland, while the land area required to meet those same fuel needs 

1722 using algal biodiesel would be less than 3 percent of all U.S. cropland in 2007 (Chisti, 2007). 

1723 Moreover, algae cultivation does not require arable land. Algae’s lack of dependence on fertile 

1724 soil and rainfall essentially eliminates competition among food, feed, and energy production 

1725 facilities for land resources (Muhs et al., 2009). Because algae-based biofuel production facilities 

1726 do not require specific land types, they may be sited closer to demand centers, reducing the need 

1727 to transport significant quantities of either biofuel or feedstock from one region of the country 

1728 (e.g., the Midwest) to another (e.g., coastal population centers). 

1729 Proximity to input sources, such as carbon dioxide sources, and output markets, as well 

1730 as the availability of affordable land, will likely drive algae production facility siting decisions. 

1731 The U.S. Southwest is viewed as a promising location for economic algae-to-biofuel cultivation 

1732 due to the availability of saline ground water, high exposure to solar radiation, and low current 

1733 land use development. Based on pilot studies and literature on algae cultivation, likely areas for 

1734 siting algae-based biofuels facilities also include coasts, marginal lands, and even co-location 

1735 with wastewater plants (Sheehan et al., 2004; U.S. EPA, 2010b). Algae grown in conjunction 

1736 with animal and human wastewater treatment facilities can reduce both freshwater demands and 

1737 fertilizer inputs, and may even generate revenue by reducing wastewater treatment costs. U.S. 

1738 companies are already using wastewater nutrients to feed algae in intensively managed open 

1739 systems for treatment of hazardous contaminants (Munoz and Guieysse, 2006). 

1740 3.5.1.2 Overview of Environmental Impacts

1741 Algae-based biofuel production systems are still being investigated at the pilot stage 

1742 using smaller-scale prototype research facilities. Evaluating the potential environmental and 

1743 resource impacts of full-scale production is highly uncertain because much of the current 

1744 relevant data is proprietary or otherwise unavailable, and many key parameters are unknown, 

1745 including where and how algae will be produced and what species and strains of algae will be 

1746 used as feedstocks. 

1747 Algae cultivation can require the use of pesticides, fertilizers, water, and fuel. Each of 

1748 these activities, in turn, can impact air quality, water quality, and water availability. (Soil quality 

1749 is not a concern.) In addition to these impacts, there is potential for invasive algae strains to 

1750 escape from cultivation (NRDC, 2009). Industrial oil extraction and biodiesel production, 

1751 biodiesel and byproduct transport and storage, and biodiesel and byproduct end use also entail

1752 environmental impacts, which are discussed further in Chapter 4. 

1753 3.5.2 Water Quality

1754 Scaled production of algae oil for biofuels has not yet been demonstrated; therefore, 

1755 water quality impacts associated with large-scale use of algae-based biofuels are currently 
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1756 speculative. Wastewater is a key factor influencing water quality impacts of algae production 

1757 facilities, including whether wastewater is used as a water source for algae cultivation, and 

1758 whether wastewater is discharged from the algae cultivation site. According to the National 

1759 Resources Defense Council, wastewater from the dewatering stages of algae production could be 

1760 released directly, sent to a treatment unit and released, or recycled back as make up water, 

1761 depending on the process (NRDC, 2009). Depending on the treatment requirements, release of 

1762 wastewater could potentially introduce chemicals, nutrients, additives (e.g., from flocculation), 

1763 and algae, including non-native species, into receiving waters.

1764 Co-locating algae production facilities with wastewater treatment plants, fossil fuel 

1765 power plants, or other industrial pollution sources can improve water quality and utilize waste 

1766 heat that contributes to thermal pollution, while reducing freshwater demands and fertilizer 

1767 inputs (Baliga and Powers, 2010; Clarens et al., 2010). By co-locating these facilities, partially 

1768 treated wastewater acts as the influent to the algae cultivation system. Algae remove nutrients as 

1769 they grow, which improves the quality of the wastewater and reduces nutrient inputs to receiving 

1770 waters. If fresh water or ground water is used as the influent, nutrients must be added artificially 

1771 in the form of fertilizer.

1772 Significant environmental benefits could be associated with the ability of algae to thrive 

1773 in polluted wastewater. Algae can improve wastewater quality by removing not only nutrients, 

1774 but also metals and other contaminants, and by emitting oxygen. Thus, algae can effectively 

1775 provide some degree of “treatment” for the wastewater (Darnall et al., 1986; Hoffmann, 1998). 

1776 3.5.3 Water Quantity

1777 3.5.3.1 Water Use

1778 Water is a critical consideration in algae cultivation. Factors influencing water use 

1779 include the algae species cultivated, the geographic location of production facilities, the 

1780 production process employed, and the source water chemistry and characteristics. Estimates for 

1781 water consumption vary widely, ranging from 25 to 974 gallons of water per gallon of biodiesel 

1782 produced (U.S. EPA, 2010b). EPA has estimated that an open-system-type biofuel facility 

1783 generating 10 million gallons of biofuel each year would use between 2,710 and 9,740 million 

1784 gallons of saline water each year; a similar scale photobioreactor-type facility would use between 

1785 250 and 720 million gallons of saline water annually (U.S. EPA, 2010b, Table 2.4-56, p. 426). 

1786 The harvesting and extraction processes also require water, but data on specific water 

1787 needs for these steps are limited (U.S. EPA, 2010b). Compared to the water required for algae 

1788 growth, however, demands are expected to be much lower. 

1789 3.5.3.2 Water Availability

1790 Depending on the cultivation system, algae production could exacerbate or create water 

1791 availability problems, especially in promising locations like the Southwest, which are already 

1792 experiencing water shortages. However, the water used to grow algae does not have to be high1793 quality fresh water. Algae can thrive in brackish water, with salt concentrations up to twice that 

1794 of seawater (U.S. EPA, 2010b), as well as in contaminated wastewater such as agricultural, 

1795 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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1835 release might have on native aquatic ecosystems, particularly if the algae released have been 

1836 artificially selected or genetically engineered to be highly productive and possibly adaptable to a 

1837 range of conditions. 

1838 3.5.6.2 Invasive Algae 

1839 The potential for biofuel algae to be released into and survive and proliferate in the 

1840 environment is, at present, highly uncertain. This potential will vary, depending on what species 

1841 and strains of naturally occurring, selectively bred, or genetically engineered algae are used and 

1842 how they are cultivated. 

1843 The risk of algae dispersal into the environment is much lower in closed bioreactor 

1844 systems than open system production, though unintentional spills from bioreactors in enclosed 

1845 production facilities are possible. High winds blowing across open systems may carry algae long 

1846 distances, depositing them in water bodies, including wetlands, near and far. Designers of coastal 

1847 algae production plants must take into account hurricanes and other severe storms that could 

1848 disperse algae over large areas. Wildlife, including birds, may also disperse algae. Closed 

1849 systems, in addition to limiting algae dispersal, have the benefit of protecting algal media from 

1850 being contaminated with other microbes, which could compete with the cultivation strains for 

1851 nutrient resources.

1852 Effluent from algal biomass dewatering processes may contain residual algae, which 

1853 could thrive in receiving waters. Treatment strategies will need to be developed to prevent algae 

1854 in effluent from contaminating the surrounding ecosystem. 

1855 The ability of cultivated algae to survive and reproduce in the natural environment is 

1856 unknown: one theoretical study suggests that some, but not all, strains with the most desirable 

1857 commercial characteristics would be out-competed by native algae (Flynn et al., 2010). Further 

1858 empirical work is critical to determine competitive and hybridizing abilities of biofuel algae in 

1859 the natural environment and to measure possible effects on algal community dynamics and 

1860 ecosystem services.

1861 3.5.7 Assessment

1862 3.5.7.1 Current and Future Impacts

1863 With the exception of nutrients, open system cultivation requires far more resources than 

1864 photobioreactor systems. Regardless which type of system is used commercially, future increases 

1865 in production of algal biomass have the potential to impact water availability and quality, air 

1866 quality and atmospheric climate, and ecosystem health and biodiversity. However, due to the 

1867 lack of data on commercial-scale algal biofuel production processes, it is uncertain what these 

1868 impacts will be.

1869 In some cases, the algal production process could prove environmentally beneficial. For 

1870 example, use of wastewater effluent, particularly partially treated wastewater, to cultivate algae 

1871 provides benefits of removing nutrients from the wastewater and reduces the environmental 

1872 impact of the production process. Combining commercial-scale algae production facilities with 
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1873 wastewater treatment plants may therefore create synergies that increase algae yields while 

1874 decreasing environmental impacts of both facilities. 

1875 Key points to understanding the potential environmental impacts of using algae for 

1876 biofuel production are described below.

1877 Water Quality: The water quality impacts of algal biofuel production will depend on both 

1878 the source of water used for cultivation and the quality of the water released from the production 

1879 facility. Algae production facilities co-located with water treatment plants, fossil fuel power 

1880 plants, or other industrial sources of pollution could have a positive impact on water quality. 

1881 However, release of wastewater from an algal biofuel production process—especially salinated 

1882 wastewater released into a freshwater environment—could adversely affect water quality.

1883 Water Quantity: Water is an important input in the algae cultivation process; increased 

1884 production of algal biofuels will impact water availability, especially in areas where water is 

1885 already scarce. However, algae may be less water intensive than other feedstocks. Moreover, 

1886 because algae can thrive in brackish and untreated waters, they are an ideal feedstock for water1887 stressed locations.

1888 Soil Quality: Soil quality impacts are likely to be minimal, based on existing studies.

1889 Air Quality: Little is known about how algal biofuel production will affect air quality. 

1890 However, preliminary data suggest that open system cultivation systems have a greater potential 

1891 than photobioreactor systems to adversely affect air quality. 

1892 Ecosystem Health/Biodiversity: Little is known about how increases in algal biofuel 

1893 production might affect biodiversity. Because algae demands substantial amounts of water, its 

1894 cultivation could adversely impact native species in water-stressed locations. Compared with 

1895 other feedstocks, however, algae is not water intensive. Also unknown are what impacts an 

1896 accidental release of algae might have on native aquatic ecosystems. Algae require low inputs of 

1897 fertilizers and pesticides compared to other feedstocks, which may also translate into fewer 

1898 ecological impacts to aquatic ecosystems

1899 Invasive Species: The ability of cultivated algae to escape into and survive in the natural 

1900 environment is uncertain. Experts speculate that photobioreactor cultivation systems would be 

1901 superior to open systems in preventing the escape of cultivated algae.

1902 3.5.7.2 Key Uncertainties and Unknowns

1903 • Most of the uncertainties related to the production of algae for biodiesel stem 

1904 from a lack of knowledge about which technologies may be used in future 

1905 commercial applications, where they will be located, and what species and strains 

1906 of algae will be used.

 1907 

1908 • Water availability impacts from feedstock growth will depend on where the algae 

1909 are grown, if open or closed systems are used, and whether water is recycled.

 1910 
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3.6

1912 3.6.1 Introduction

1911 Waste-Based Feedstocks

1913 Diverse wastes, including construction debris, municipal solid waste (MSW), yard waste, 

1914 food waste, and animal waste, have the potential to serve as biofuel feedstocks. Depending on 

1915 the waste, conversion system, and product, potential exists for municipalities, industries, and 

1916 farmers to transform a material with high management costs to a resource that generates energy 

1917 and profits. In some instances, diverting waste that cannot be recycled or reused to fuel has been 

1918 found to reduce land-filled materials by 90 percent, helping to also extend the lifetime capacity 

1919 of the landfill (Helou et al., 2010). 

1920 Tapping into waste energy sources has many challenges, including dispersed locations 

1921 and potentially high transport costs; lack of long-term performance data; the cost of converting 

1922 waste to energy, and the possibility that the resulting biofuel might not meet quality or regulatory 

1923 specifications for use (Bracmort and Gorte, 2010). 

1924 Use of wastes as biofuel feedstocks will vary based on their availability, the ability of 

1925 conversion technologies to handle the material, and the comparative economics of their use for 

1926 fuel versus power and other products. Types and quantities of wastes used will vary by region. A

1927 large number and variety of waste-based materials are being investigated and implemented as 

1928 feedstocks for ethanol and biodiesel, mostly on local scales. For example, several states—e.g., 

1929 Massachusetts (Advanced Biofuels Task Force, 2008; Timmons et al., 2008), California (Chester 

et al., 2007), and Ohio20

1933 3.6.2 Municipal Solid Waste

1930 —have explored waste availability and its potential to meet regional 

1931 energy needs, either for power or for transportation fuel. Feedstocks may be converted to biofuel 

1932 or used as an energy source to power a biorefinery. 

1934 The biogenic portion of municipal solid waste (paper, wood, yard trimmings, textiles, and 

1935 other materials that are not plastic- or rubber-based), has the potential to be a significant 

1936 feedstock for ethanol and other biofuels. Using 2005 data, the U.S. Energy Information 

1937 Administration calculated that 94 million tons (MT) (about 56 percent) of the 167.8 MT of MSW 

1938 waste generated that year had biogenic BTU content (EIA, 2007). This estimate included food 

1939 waste (the third largest component by weight), which is also potentially viable as a biofuel 

1940 feedstock in addition to biogenic material listed above. Some producers claim to have 

1941 thermochemically-based technology that can yield 120 gallons of ethanol per ton of MSW, and 

1942 therefore, this could serve as a rough MSW yield estimate. (Fulcrum Bioenergy, 2009). 

1943 Accepting this estimate, the 94 MT of biogenic MSW generated in the U.S. in 2005 would have 

1944 the potential to generate up to 11 billion gallons of ethanol. While this is not a likely scenario 

1945 (since, for example, some of the biogenic fraction—paper, wood, etc.—would be recycled or 

1946 reused), it demonstrates that MSW could be a significant source for biofuel. In addition, there are 

1947 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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1948 diverting solid waste from landfills and incinerators, extending their useful life, and reserving 

1949 that capacity for materials that cannot be recycled or reused.

1950 3.6.3 Other Wastes

1951 Several types of waste materials that currently present environmental and economic 

1952 challenges have the potential to be harnessed as feedstock for biofuel. These materials include 

1953 waste oil and grease, food processing wastes, and livestock waste (Antizar-Ladislao and Turrion1954 Gomez, 2008; Helou et al., 2010). 

1955 The U.S. Department of Energy estimates that the restaurant industry generates 9 pounds 

1956 of waste oil per person annually, and that the nation’s wastewater contains roughly 13 pounds of 

1957 grease per person per year (Wiltsee, 1998). Several municipalities and industries have 

1958 implemented collection programs, and are converting these wastes to biodiesel.

1959 Annually, the U.S. generates an estimated 48 million tons of food processing wastes (i.e., 

1960 food residues produced during agricultural and industrial operations), not including food waste 

1961 disposed and processed through wastewater treatment plants (Kantor et al., 1997). These wastes 

1962 have potential a biofuel feedstocks. 

1963 The U.S. generates over 1 billion tons of manure, biosolids, and industrial by-products 

1964 each year (ARS, n.d.). The amount of manure generated at confined and other types of animal 

1965 feeding operations in the U.S. is estimated to exceed 335 million tons of dry matter per year 

1966 (ARS, n.d.). While much of this manure is applied to cropland and pasture as fertilizer, excess is 

1967 often available and could be tapped as a biofuel feedstock. It has been estimated that around 10 

1968 percent of current manure production could be used for bioenergy purposes under current land 

1969 use patterns once sustainability concerns are met (i.e., this manure is available after primary use 

1970 of manure on soils to maintain fertility) (Perlack et al., 2005). Methane emissions from livestock 

1971 manure management systems, which account for a significant percentage (10 percent, or 17.0 

1972 million metric tonnes of carbon equivalent [MMTCE] [3.0 teragrams, or Tg] in 1997) of the total 

1973 U.S. methane emissions, are another potential energy source (U.S. EPA, 1999). 

1974 Using any of these excess waste materials as biofuel feedstocks has potential to create a 

1975 higher value use with significant environmental and economic benefits. 

1976 3.6.4 Environmental Impacts of Waste-Based Biofuel 

1977 Waste-based biofuels are expected to have both environmental benefits and impacts. On 

1978 the positive side, for example, diverting waste from landfills avoids generation of landfill 

1979 methane gases, and diverting waste and trap greases from wastewater treatment plants helps 

1980 avoid costly plant upsets that contribute to combined sewer overflow. Biorefineries that use 

1981 wastes, particularly MSW, tend to be located in proximity to the waste source, which correlates 

1982 well with the densely populated end-users of transportation fuels and helps reduce the GHG 

1983 lifecycle footprint of waste-derived fuels (Antizar-Ladislao and Turrion-Gomez, 2008; Williams 

1984 et al., 2009). 

1985 More information is needed to understand and evaluate the environmental effects of 

1986 waste-based biofuels. Different wastes have different characteristics, including size, volume, 
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1987 heterogeneity, moisture content, and energy value. These characteristics will, to a large degree, 

1988 determine feasible and appropriate collection, processing, and conversion methods, which in turn 

1989 will determine net energy gain, as well as environmental impacts such as air and GHG 

1990 emissions. Research is needed to compare the benefits and impacts of various technological 

1991 options for converting MSW to biofuel, and to compare, on a regional basis, the environmental 

1992 benefits and impacts of MSW to other biofuel feedstocks. Currently, data are lacking for such 

1993 comparisons. Comparative life cycle assessments that consider both the direct impacts or 

1994 benefits and indirect impacts or benefits (e.g., impacts of reduced landfilling of MSW) are 

1995 needed to understand the true value of waste as an alternative feedstock. 

1996 Assessment and Uncertainty 

1997 There have been comparatively few attempts at assessing the environmental impacts 

1998 associated with the production and use of waste-based biofuels (Williams et al., 2009). In 

1999 general, waste as a feedstock is expected to have a smaller environmental impact than 

2000 conventional feedstocks. However, the choice of waste management options and the particular 

2001 technology for energy recovery will influence the environmental medium impacted and the level 

2002 of impact (Chester and Martin, 2009; Kalogo et al., 2007). As the number of waste conversion 

2003 facilities increases, environmental monitoring and research will be needed to address the 

2004 information gaps that currently limit environmental assessment.

3.7

2006 EISA Section 204 requires an assessment of the impacts of biofuels on a variety of 

2007 environmental and resource conservation issues, including impacts on forests, grasslands, and 

2008 wetlands. This section provides an overview of impacts on these specific habitats. 

2005 Summary of Feedstock-Dependent Impacts on Specialized Habitats

2009 3.7.1 Forests

2010 Woody biomass is the feedstock most likely to affect forests; row crops, algae, and most 

2011 perennial grasses are unlikely to have an impact on this habitat. 

2012 Section 211(o) of the Clean Air Act limits planting of short-rotation woody crops and 

2013 harvesting of tree residue to actively managed tree plantations on non-federal land that was 

2014 cleared prior to December 19, 2007, or to non-federal forestlands; and limits removal of slash 

2015 and pre-commercial thinning to non-federal forestlands. However, as described in Table 3-5, a 

2016 variety of activities associated with producing woody biomass feedstock may impact forests. 

2017 
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Table 3-5: Overview of Impacts on Forests from Different Types of Biofuel Feedstocks

Feedstock Forest Impact

Report 

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, longerrotations, 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.

 2018 

2019 3.7.2 Grasslands 

2020 Production of row crops and perennial grasses for biofuel feedstocks can impact 

2021 grasslands, although perennial grasses may also have some positive effects on grasslands. 

2022 In addition to the restrictions on forested sources of renewable biomass mentioned above, 

2023 Section 211(o) of the Clean Air Act more broadly limits the lands on which any biofuel 

2024 feedstock can be produced to those that were cleared or cultivated at any time prior to December 

2025 19, 2007, either in active management or fallow and non-forested. Therefore, grassland that 

2026 remained uncultivated as of December 19, 2007, may not be converted to grow biofuel. Most of 

2027 lands that would be eligible for renewable biomass production under the Clean Air Act, because 

2028 they were cultivated at some point prior to December 19, 2007, are now part of the Conservation 

2029 Reserve Program (see Section 3.2.1.1). The USDA estimates that the vast majority (78 percent) 

2030 of lands that will be taken out of the CRP to grown biofuel feedstock will be grasslands (FSA, 

2031 2008). Therefore, conversion of CRP lands to grow biofuels will impact grassland ecosystems, as 

2032 will other aspects of biofuel feedstock production (Table 3-6).

2033 
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Table 3-6: Overview of Impacts on Grasslands from Different Types of Biofuel Feedstocks

Feedstock Grasslands Impact

Report 

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

Feedstock Wetlands Impact

Report 

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

2042 Genetic engineering of crops has a history of research, development, and 

2043 commercialization that extends back for more than 15 years. Along with the growth of this 

2044 biotechnology industry, the U.S. established a coordinated framework for regulatory oversight in 

2045 1986 (OSTP, 1986). Since then, the relevant agencies (EPA, USDA, and Food and Drug 

2046 Administration) have implemented risk assessment programs that allow informed environmental 

2047 decision-making prior to commercialization. These programs have been independently assessed 

2048 over the years (NRC, 2000, 2001, 2002) and improvements made to ensure the safety of the 

2049 products. At the same time, the methodology for biotechnology risk assessment has been 

2050 scrutinized and general frameworks created to facilitate robust approaches and harmonize the 

2051 processes internationally (Craig et al., 2008; Auer, 2008; Nickson, 2008; Romeis et al., 2008; 

2052 Raybould, 2007; Andow and Zwalen, 2006; Conner et al., 2003; Pollard et al., 2004). This 

2053 section describes environmental concerns associated with Genetically Modified Organisms 

2054 (GMOs) that are currently used as biofuel feedstocks, as well as anticipated concerns for GMOs 

2055 that will be developed for the next generation of biofuel feedstocks. 

2041 Genetically Engineered Feedstocks

2056 As indicated earlier in this chapter, great advantage has already been taken for genetically 

2057 engineered corn and soybean, which are now grown worldwide, along with other engineered 

2058 crops. Brookes and Barfoot have conducted a series of extensive post-commercialization 

2059 assessments of genetically engineered maize, soybeans, cotton, sugar beets, and canola varieties 

2060 at 10-year intervals (Brookes and Barfoot, 2006, 2008, 2009, 2010). In these analyses, the 

2061 authors found consistent reductions in the amounts of pesticides used and a reduction in GHG 

2062 emissions for agricultural systems where these GMO crops are grown. These results are 

2063 supported by others (Brinmer et al., 2005; Knox et al., 2006), although regional differences in the 

2064 reductions have been noted (Kleter et al., 2008). The results for corn and soybean independently 

2065 are consistent with the general trends (Brookes and Barfoot, 2010). Assuming that current 

2066 genetically engineered varieties of corn and soybeans receive continued regulatory oversight, no 

2067 additional environmental concerns are anticipated with these organisms in their current genetic 

2068 configuration, even with an increase in their production. However, as feedstocks for biofuel 

2069 change to accommodate cellulosic technologies and algae production, the range of environmental 

2070 considerations, including impacts from GMO varieties, will change as well (Wilkinson and 

2071 Tepfer, 2009; Lee et al., 2009).

2072 To harness the full potential of biomass, the genetic engineering of feedstocks has been 

2073 recognized as a key technology (Gressel 2008; Antizar-Ladislao and Turrion-Gomez, 2008; 

2074 Sexton et al., 2009). The approaches being considered include increasing plant biomass by 

2075 delaying flowering, altering plant growth regulators, and manipulating photosynthetic processes; 

2076 modifying traits (e.g., herbicide tolerance, insect resistance) in non-row crop plants that reduce 

2077 cultivation inputs; and modifying cellulose/lignin composition and other traits that result in cost 

2078 reductions in bioprocessing (i.e., facilitating the biorefinery process) (Sticklen 2007, 2009; 

2079 Ragauskas et al., 2006; Gressel 2008). These new varieties may have implications for the 

2080 environment beyond what has been considered in first generation biotechnology crops, and the 

2081 scientific community has begun to examine whether and how well existing risk assessment 

2082 procedures will work for bioenergy crops (Wolt, 2009; Chapotin and Wolt, 2007; Wilkinson and 

2083 Teper, 2009; Firbank 2007; Lee et al. 2009). For example, some first attempts have been made at 
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2084 evaluating feedstocks with particular traits; suggestions for minimizing environmental impacts 

2085 are incorporated (Kausch et al., 2010a, 2010b). 
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1 4. BIOFUEL PRODUCTION, TRANSPORT, STORAGE AND END USE

4.1

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 

4.5). 6 

2 Introduction

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. 

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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20 Air emissions associated with end use of ethanol combustion are relatively independent 

21 of feedstock or conversion process, whereas biodiesel emissions are highly dependent on 

22 feedstock type. As discussed later in the chapter, biofuel combustion may result in higher 

23 emissions of some pollutants compared to gasoline combustion, and lower emissions of others. 

24 Biofuel production may require use of water, which may contribute to ground water 

25 depletion or lower surface water flow, depending on the amount of water withdrawn and water 

26 availability. Potential water quality impacts include wastewater discharge during the conversion 

27 process and the potential for leaks and spills to surface and groundwater during biofuel handling, 

28 transport, and storage. Additionally, phosphorus runoff from the manure of animals that have 

29 been fed an ethanol by-product, dried distillers grains with solubles, which has a high 

30 phosphorus content (Regassa et al., 2008), may have the potential to impact water quality. 

31 Possible air and water impacts associated with ethanol and biodiesel, as well as 

32 opportunities for mitigation, are discussed in Sections 4.2 to 4.5. Discussion focuses primarily on 

33 the impacts of corn ethanol and diesel from soybean, since these constitute the vast majority of 

34 biofuel produced and used in the U.S. as of July 2010. 

4.2

36 4.2.1 Handling, Storage, and Transport

35 Feedstock Logistics

37 Feedstock logistics comprise activities associated with handling, storing, and transporting 

38 feedstocks after harvest to the point where the feedstocks are converted to biofuel. The most 

39 significant environmental impacts of these activities are the emissions associated with energy 

40 use. Both greenhouse gases (GHG) and criteria pollutant emissions result from the combustion of 

41 fuels used during transportation. In general, feedstock logistics may be optimized, and emissions 

42 reduced, by integrating feedstocks, processing facilities, and consumer demands at a regional 

43 scale to minimize transport distances.

44 4.2.1.1 Ethanol 

45 Harvested corn is transported to a biorefinery where it is converted to ethanol and a 

46 number of co-products. Air quality will be impacted by emissions from the combustion of fuels 

47 used for transportation vehicles and equipment. 

48 4.2.1.2 Biodiesel

49 After harvest, soybeans are transported from fields to the drying site, storehouse, or 

50 collection center, followed by transport to the biodiesel refinery. Air quality may be affected by 

51 emissions from the combustion of fuels used for transportation vehicles and equipment. 
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4.3

53 4.3.1 Biofuel Conversion Processes

52 Biofuel Production

54 4.3.1.1 Ethanol 

55 As of November 2009, there were 180 corn starch ethanol facilities in the U.S. with a 

combined capacity of 12 billion gallons per year (bgy) (U.S. EPA, 2010b, footnote 250).21

62 Conventional ethanol is produced from the fermentation of corn starch. Two methods are 

63 currently utilized: 

56 At 

57 that time, 27 of these (representing 1,400 million gallons per year (mgy) of capacity) were idled, 

58 and another 10 facilities, with a combined capacity of 1,301 mgy, were under construction (U.S. 

59 EPA, 2010b, p.137). These facilities are located in the major corn-producing region of the 

60 country: Iowa (the largest production capacity and the greatest number of plants) followed by 

61 Nebraska, Minnesota, Indiana, and Illinois (U.S. EPA, 2010b). 

64 • Dry milling, in which the corn kernel is first ground into a meal, usually without 

65 separating out the various component parts of the grain. The meal is then slurried 

66 with water and cooked at high temperatures to form a mash, which then 

67 undergoes fermentation. Dry milling is more commonly used than wet milling.

 68 

69 • Wet milling, in which the kernels are steeped in water to separate out the germ, 

70 fiber, and gluten (fractionation). From this initial separation, co-products such as 

71 corn meal, corn gluten meal, and corn gluten feed are recovered. The remaining 

72 mash contains the water-soluble starch, which undergoes further processing for 

73 biofuel. 

 74 

75 In both processes, soluble starch is subsequently converted to a simple sugar (glucose) 

76 through saccharification, an enzyme-catalyzed hydrolysis reaction. This is followed by yeast 

77 fermentation of the glucose to ethanol. Following fermentation, the mash is distilled to collect 

78 the ethanol as a mixture of 95 percent alcohol and 5 percent water. A subsequent dehydration 

79 step is required to remove the aqueous portion to yield 99.5 percent pure ethanol. 

80 Substantial efforts are under way to develop processes to convert feedstocks containing 

81 cellulose into biofuels. These cellulosic feedstocks are primarily composed of cellulose, 

82 hemicellulose, and lignin polymers. Currently, two major pathways exist for converting 

83 cellulosic feedstocks into biofuel: 

84 • Biochemical conversion using a physical and chemical process to liberate tightly 

85 bound cellulose and hemicellulose from lignin. The process uses strong acid or 

86 enzymes (cellulases) to hydrolyze the cellulose and hemicelluloses to glucose and 

87 other simple sugars, followed by microbial fermentation of the sugars into 

88 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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89 • Thermochemical conversion involving gasification or pyrolysis. 

 90 

91 — In the gasification process, biomass is heated at high temperatures with a 

92 controlled amount of oxygen to decompose the cellulosic material. This 

93 yields a mixture comprised mainly of carbon monoxide and hydrogen 

94 known as syngas. 

 95 

96 — In pyrolysis, the biomass is heated in the absence of oxygen at lower 

97 temperatures than used in gasification. The product is a liquid bio-oil that 

98 can be used subsequently as a feedstock for a petroleum refinery. 

 99 

100 Other cellulosic conversion processes are in various stages of development, from concept 

101 stage to pilot-scale development, and to demonstration plant construction. Although no U.S. 

102 commercial-scale plants are operating as of July 2010, several companies are expected to have 

103 facilities operating within the next few years.

104 4.3.1.2 Biodiesel

105 As of November 2009, there were approximately 191 biodiesel facilities in the U.S., with 

106 a combined capacity of 2.8 billion gallons per year (bgy) (U.S. EPA, 2010b). Total domestic 

107 production of biodiesel in 2009 was 505 mgy—much less than domestic production capacity. 

108 The dominant technology used to produce biodiesel involves a transesterification reaction in 

109 which triglycerides (fats) from the oil are converted to esters in the presence of an alcohol and a 

110 catalyst, such as potassium hydroxide. Plant oils (soy, rape, palm, algae, etc.) and other 

111 feedstocks (e.g., animal-derived oil such as lard and tallow, recycled oil and grease from 

112 restaurants and food processing plants) provide sources of triglycerides for conversion to 

113 biodiesel. Free glycerol, or glycerin, is a major co-product in transesterification, comprising an 

114 estimated 10 percent of the final product (U.S. EPA, 2010b). Table 4-1, below shows the 

115 breakdown of feedstocks used to produce biodiesel in the U.S. in 2009. Soybean oil made up the 

116 majority of biodiesel feedstock, comprising 54 percent. 

Table 4-1. 2009 Summary of Inputs to U.S. Biodiesel Production

Input 2009 Total (lbs.) Percentage of 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

Input 2009 Total (lbs.) Percentage of Total

Other Inputs Alcohol 328 9.0%

Catalysts 56 1.5%

117 Source: EIA, 2010

118 

119 Commercial processes for large-scale algae production and algal oil collection are 

120 currently being developed as another plant oil source for biodiesel (U.S. EPA, 2010b). Lipid 

121 extraction and drying currently are energy-intensive steps in the algae diesel production process. 

122 Other processing techniques are currently being investigated, including enzymatic conversion 

123 and catalytic cracking of algal oil, pyrolysis, and gasification of algae. However, lipid extraction 

124 via solvents followed by transesterification remains the most commonly used method for algal 

125 oil processing (U.S. DOE, 2010). Until commercial facilities using mature technologies go into 

126 production, the impacts from algal conversion will be uncertain.

127 In addition to transesterification, other methods for converting seed oils, algal oils, and 

128 animal fats into biofuel have been developed recently using technologies that are already widely 

129 employed in petroleum refineries (Huo et al., 2009). Hydrotreating technologies utilize seed oils 

130 or animal fats to produce an isoparaffin-rich diesel substitute referred to as “green diesel” or 

131 renewable diesel (Huo et al., 2008). 

132 Although the transesterification process can generate a much larger amount of diesel 

133 product than the other processes, as noted above, it requires more energy and chemical inputs 

134 (Huo et al., 2008). In the case of biodiesel hydro-generation technology, inputs such as 

135 hydrogen, which are very energy-intensive to produce, must be taken into consideration in a full 

136 life cycle assessment in order to adequately evaluate energy efficiency of each fuel production 

137 process. Compared with conventional diesel and biodiesel, renewable diesel fuels have much 

138 higher cetane numbers (a measure of diesel fuel quality).

139 4.3.2 Air Quality

140 Air quality impacts associated with the production of biofuels occur throughout the 

141 production chain (Figure 4-1). EPA’s Regulatory Impact Analysis (RIA) of the revisions to the 

142 national Renewable Fuel Standard Program (RFS2) assessed the air pollutant emissions and air 

143 quality impacts of the biofuel volumes (see Table 2-1 in Chapter 2) required under the 2007 

144 Energy Independence and Security Act (EISA). The discussion below summarizes the RIA 

145 results; the interested reader is referred to the RIA for additional details (U.S. EPA, 2010b). 

The RIA analysis22,23

 

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.

146 focused on the projected impact of the renewable fuel volumes 

147 required in 2022, and accounted for GHG life cycle emissions, as well as the displaced 

148 petroleum consumption associated with use of biofuels. The emission impacts of the 2022 RFS2 

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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149 volumes were quantified relative to two reference cases: 1) the original RFS program (RFS1) 

150 mandate volume of 7.5 billion gallons of renewable fuel (6.7 billion gallons ethanol), and 2) the 

151 U.S. Department of Energy (DOE) Annual Energy Outlook (AEO) 2007 projected 2022 volume 

152 of 13.6 billion gallons of renewable fuels. The RIA analysis found decreases in overall emissions 

153 for carbon monoxide (CO) and benzene, and increases in overall emissions for nitrogen oxide 

154 (NOx), volatile organic compounds (VOCs), PM, and several air toxics, especially ethanol and 

155 acetaldehyde. Overall emissions of sulfur dioxide (SO2) exhibited mixed results, depending on 

156 the fuel effect specified.

157 For biofuel production and distribution, the net change in VOC, CO, NOx, and PM 

158 emissions can be attributed to two effects: 1) emission increases connected with biofuel 

159 production, and 2) emission decreases associated with reductions in gasoline production and 

160 distribution as ethanol displaces gasoline. Increases in fine particles less than 2.5 micrometers in 

161 diameter (PM2.5), sulfur oxide (SOx), and especially NOx were determined to be driven by 

162 stationary combustion emissions from the substantial increase in corn and cellulosic ethanol 

163 production. Substantial fugitive dust and particulate increases are also associated

164 with agricultural operations. 

165 The RIA found that increasing the production and distribution of ethanol would lead to 

166 higher ethanol vapor emissions. To a lesser degree, the production and distribution of greater 

167 amounts of ethanol would lead to increases in emissions of formaldehyde and acrolein, as well as 

168 very small decreases in benzene, 1,3-butadiene, and naphthalene emissions relative to the total 

169 volume of these emissions in the U.S. Emissions of ammonia are expected to increase 

170 substantially due to increased ammonia from fertilizer use. Additional details on EPA’s analysis 

171 of changes in emissions associated with the RFS2 volumes can be found in 

172 www.epa.gov/otaq/fuels/renewablefuels/regulations.htm. 

173 Air pollutant emissions associated with the conversion of biomass to fuel may be 

174 mitigated through the use of cleaner fuels during the conversion process and more efficient 

175 process and energy generation equipment. The majority of ethanol plants built in recent years, 

176 and expected to be built in the near future, utilize dry mill technology (Wang et al., 2007a). 

177 Because most ethanol plants utilize similar dry milling production processes, differences in 

178 environmental impacts among plants are primarily due to each plant’s choice of fuel. EPA’s RIA 

179 assumes a dry mill for the base scenario.

180 EPA’s RIA examines the impacts of using energy-saving technologies such as combined 

181 heat and power (CHP). CHP is an effective means to reduce air emissions associated with biofuel 

182 production (both ethanol and biodiesel). CHP generates electricity by burning natural gas or 

183 biogas, and then employs a heat recovery unit to capture heat from the exhaust stream as thermal 

184 energy. Using energy from the same fuel source significantly reduces the total fuel used by 

185 facilities along with the corresponding emissions of carbon dioxide (CO2) and other pollutants. 

186 Fractionation, membrane separation, and raw starch hydrolysis are additional technologies 

187 examined in EPA’s RIA that increase process efficiencies by enabling producers to sell distillers 

188 grains (a co-product of the corn-ethanol conversion process) wet rather than dry, thereby 

189 reducing greenhouse gas emissions and other possible environmental impacts (since drying 

190 distillers grains is an energy-intensive process). 
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191 4.3.2.1 Ethanol 

192 Ethanol production requires electricity and the use of steam. Electricity is either 

193 purchased from the grid or produced onsite, and steam is typically produced onsite from natural 

194 gas. Power and the energy used to fuel boilers are responsible for emissions of VOCs, PM, CO, 

195 SOx and NOx (U.S. EPA, 2010b; Wang et al., 2007b). For corn-based ethanol, fossil fuels such 

196 as natural gas are typically used to produce heat during the conversion process, although a 

197 number of corn ethanol facilities are exploring new technologies with the potential to reduce 

198 their energy requirements.

199 A number of processes at ethanol production facilities result in emissions of air toxics. 

200 These processes include fermentation, distillation of the resultant mash, and drying of spent wet 

201 grain to produce animal feed. Emissions of air toxics vary tremendously from facility to facility 

202 due to a variety of factors, and it is difficult to determine how differences in the production 

203 processes individually impact emissions (U.S. EPA, 2010b). Ethanol vapor and air toxic 

204 emissions associated with biofuel production were projected to increase in EPA’s RFS2 RIA, but 

205 these would be very small compared to current emissions (U.S. EPA, 2010b). 

206 4.3.2.2 Biodiesel

207 While the production process for biodiesel is fundamentally different from ethanol, 

208 thermal and electrical energy are still required for production. The thermal energy required for 

209 biodiesel production is usually met using steam generated using a natural gas boiler. In certain 

210 situations, the glycerol co-product may also be burned to produce process heat, or a biomass 

211 boiler may be used to replace natural gas.

212 Air quality issues associated with a natural gas-fired biodiesel production process are 

213 similar to those for other natural gas applications such as ethanol production, and include 

emissions of VOCs, PM, CO, SOx, 214 and NOx. Glycerol or solid fuel biomass boilers have 

215 emissions characteristics similar to those anticipated for cellulosic ethanol plants, including 

216 increased particulates and the potential for VOCs, NOx, and SOx. 

217 Biodiesel production using a closed hot oil heater system would have none of the air 

218 emissions associated with traditional steam production. Air emissions associated with these 

219 systems would be those associated with the production of the electricity, which would take place 

220 outside the biodiesel plant boundary. 

221 Additionally, the extraction of vegetable oil to create biodiesel in large chemical 

222 processing plants is typically achieved using hexane, a VOC that EPA has classified as a 

223 hazardous air pollutant. Hexane is also commonly used to extract algal oils. Fugitive emissions 

224 of hexane may result from increased biodiesel manufacture (Hess et al., 2009). 

225 4.3.2.3 Greenhouse Gases

226 Fuel combustion at ethanol and biodiesel facilities releases greenhouse gases. 

227 Fermentation to ethanol also releases CO2. Combustion-related greenhouse gas emissions are 

228 released to the atmosphere, but some ethanol facilities capture, purify, and sell their CO2

229 associated with fermentation to the beverage industry for carbonation or to food processors for 
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230 flash freezing. Opportunities for CO2 reuse depend on the proximity of ethanol refineries to local 

231 users. The industrial gas supplier Airgas estimates that the ethanol industry captures and recovers 

232 5 to 7 percent of all CO2 that it produces from the ethanol fermentation process (spreadsheet 

233 provided to EPA by Bruce Woerner at Airgas on August 14, 2009, cited in U.S. EPA, 2010b, p. 

234 133). Other sources of GHG emissions, such as those from electricity generation produced from 

235 coal or other GHG-emitting sources, are not currently recovered by the industry. 

236 EISA Section 204 does not include GHG emissions in the set of environmental issues to 

237 be examined in this report. However, EPA did analyze life cycle GHG emissions from increased 

238 renewable fuels use as part of the EISA-mandated revisions to the RFS program. The Act 

239 established specific life cycle GHG emission thresholds for each of four types of renewable 

240 fuels, requiring a percentage improvement compared to life cycle GHG emissions for gasoline or 

241 diesel (whichever is being replaced by the renewable fuel) sold or distributed as transportation 

242 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 fuel a 20%

Advanced biofuel 50%

Biomass-based diesel 50%

Cellulosic biofuel 60%

243 a – The 20% criterion generally applies to renewable fuel from new 

244 facilities that commenced construction after December 19, 2007. 

245 EPA’s methodology for conducting the GHG life cycle assessment included use of 

246 agricultural sector economic models to determine domestic agriculture sector-wide impacts and 

247 international changes in crop production and total crop. Based on these modeling results, EPA 

248 estimated GHG emissions using DOE’s GREET model defaults and Intergovernmental Panel on 

249 Climate Change (IPCC) emission factors. The GHGs considered in the analysis were CO2, 

250 methane (CH4), and nitrous oxide (N2O). Biofuel process energy use and associated GHG 

251 emissions were based on process models for the different pathways considered. For ethanol and 

252 biodiesel, EPA’s RFS2 RIA projected that (U.S. EPA, 2010b): 

253 • Ethanol produced from corn starch at a new (or expanded capacity from an 

254 existing) natural gas-fired facility using advanced efficient technologies will 

255 comply with the 20 percent GHG emission reduction threshold. 

 256 

257 • Ethanol produced from sugarcane will comply with the 50 percent GHG reduction 

258 threshold for the advanced fuel category.

 259 

260 • Biodiesel from soybean oil and renewable diesel from waste oils, fats, and greases 

261 will comply with the 50 percent GHG threshold for the biomass-based diesel 

262 category.

 263 

264 • Diesel produced from algal oils will comply with the 50 percent GHG threshold 

265 for the biomass-based diesel category.
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266 • Cellulosic ethanol and cellulosic diesel (based on the modeled pathways) will 

267 comply with the 60 percent GHG reduction threshold applicable to cellulosic 

268 biofuels. 

 269 

270 Based on the assessment described above, EPA projected a reduction of 138 million 

271 metric tons of CO2-equivalent emissions by 2022 compared to projected 2022 emissions without 

272 the EISA-mandated changes (see the RFS2 RIA [U.S. EPA, 2010b] for details). 

273 4.3.3 Water Quality and Availability

274 All biofuel facilities utilize process water to convert biomass to fuel. Water used in the 

275 biorefining process is modest in absolute terms compared to the water applied and consumed in 

276 growing the plants used to produce biofuel. The impacts associated with water use at conversion 

277 facilities depend on the location of the facility in relation to water resources. In some regions 

278 where water is abundant, increased withdrawals may have little effect. Ground water depletion 

279 may result in increased costs to pump water from deeper wells, loss of stream flow, and 

280 subsidence of the overlying land (Reilly et al., 2008). Several areas of the country that are 

281 already experiencing lowered ground water levels (e.g., High Plains aquifer, Lower Mississippi 

282 River alluvial aquifer) correspond with regions where increased biofuel production is expected. 

283 In addition, minimum in-stream flow for aquatic life can be affected by ground water depletion 

284 because ground water discharge into streams is a major source of stream base flow. In some 

285 areas, streams have run dry due to ground water depletion, while in other areas, minimum stream 

286 flow during the summer has been sustained because of irrigation return flow to streams 

287 (Bartolino and Cunningham, 2003). In the case of sole source aquifers, ground water depletion 

288 may severely impact drinking water availability, since these areas have no readily available 

289 alternative freshwater sources (Levin et al., 2002). 

290 Comprehensive local, state, and regional water planning, as well as state regulatory 

291 controls, are critical to ensure that facilities are located in watersheds that can sustain the 

292 increased withdrawal without affecting other uses. The first step in mitigating water availability 

293 concerns associated with increased biofuel production is to locate production facilities where 

294 water sources are adequate to meet production needs without impacting other uses. Siting of 

295 biofuel facilities may also be influenced by state laws and regulations designed to avoid or 

296 mitigate conflicts among water uses. These vary by state. For example, withdrawals associated 

297 with biofuel production facilities may need a state permit to ensure that the proposed withdrawal 

298 does not result in unacceptable impacts on other users or on aquatic life. In addition, different 

299 states assign water rights in different ways. Some exercise the prior appropriation rule (i.e., water 

300 rights are determined by priority of beneficial use, meaning that the first person to use the water 

301 can acquire individual rights to the water); some are based on the English law of absolute 

302 ownership (i.e., rights to use water are connected to land ownership); some limit withdrawals 

303 based on stream flow requirements for aquatic life; and some have a hierarchy to prioritize uses 

304 of the water.

305 Like water quantity impacts, water quality impacts depend on a number of factors 

306 including facility location, water source, receiving water, type of feedstock used, biorefinery 

307 technology, effluent controls, and water re-use/recycling practices. Water quality impacts are 

308 associated with the wastewater discharge from the conversion process. Biological oxygen 
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309 demand (BOD), brine, ammonia-nitrogen, and phosphorus are primary pollutants of concern 

310 from ethanol facilities, while discharges of BOD, glycerin, and to a certain extent, total 

311 suspended solids (TSS) pose the major water quality concerns from biodiesel facility effluent. 

312 Regulatory controls placed on the quality of biofuel production wastewater discharge can 

313 mitigate water quality impacts. Discharges to publicly owned wastewater treatment works 

314 (POTWs) are subject to general pre-treatment standards in the Clean Water Act (40 CFR 403.5). 

315 Biofuel facilities that discharge their wastewater to POTWs are subject to whatever pre-treatment 

316 limitations are in force for the receiving POTW. For those facilities that treat and discharge their 

317 own wastewater, EPA has enforceable regulations to control production facility effluent 

318 discharges of BOD, sediment, and ammonia-nitrogen through the National Pollutant Discharge 

319 Elimination System (NPDES) permit program.

320 Whether effluent is discharged to a POTW or treated onsite at the production facility, 

321 BOD can lead to methane emissions during the wastewater treatment process. To mitigate the 

322 release of methane to atmosphere, facilities can install anaerobic digesters as a treatment step. 

323 Anaerobic digesters treat the biosolids contained in wastewater effluent, generating biogas that is 

324 approximately 60 to 65 percent methane. This biogas can then either be flared or captured and 

325 used as a clean energy source at the biofuel production facility or elsewhere.

326 Currently there are no effluent limitation guidelines or categorical pretreatment standards 

327 that regulate process wastewater discharges from ethanol and biodiesel manufacturing facilities.

328 4.3.3.1 Ethanol 

329 In 2007-2008, EPA evaluated biodiesel and corn ethanol manufacturing facilities. No 

330 major effluent quality issues were found from corn ethanol plants discharging to either surface 

331 waters or to wastewater treatment plants.

332 While some ethanol facilities get their process water from municipal water supplies, most 

333 use onsite wells (Wu et al., 2009). However, most untreated ground water sources are generally 

334 not suitable for process water because of their mineral content. Ground water high in mineral 

335 content is commonly treated by reverse osmosis, which requires energy and concentrates ground 

336 water minerals into reject water, with potential water quality impacts upon their release. For 

337 every two gallons of pure water produced, about a gallon of brine is discharged as reject water 

338 (U.S. EPA, 2010b). Methods to reduce the impact associated with reject water high in mineral 

339 concentration include (1) further concentration and disposal, or (2) use of in-stream dilution. 

340 Some ethanol facilities have constructed long pipelines to access additional water sources to 

341 dilute the effluent to levels that meet water quality standards.

342 Once process water is treated, most is lost as steam during the ethanol production 

343 process. Water use varies depending on the age of the facility and the type of milling process. 

344 Older generation production facilities use 4 to 6 gallons of process water to produce a gallon of 

345 ethanol; newer facilities generally use less than 3 gallons of water in the production process. 

346 Most of this water savings is gained through improved recycling of water and heat in the process. 

347 Dry milling facilities consume on average 3.45 gallons of fresh water per gallon of ethanol 

348 produced (Wu et al., 2009); newer facilities tend to consume about 27 percent less water. Wet 

349 mill facilities consume an average of 3.95 gallons of fresh water per gallon of ethanol produced 
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350 (Wu, 2008). Most estimates of water consumption in ethanol production are based on the use of 

351 clean process water and do not include the water discharged as reject water.

352 Ethanol plants are designed to recycle water within the plant, and improvements in water 

353 use efficiency of ethanol facilities are expected through steam condensate reuse and treated 

354 process water recycling (Wu et al., 2009). New technologies that improve water efficiency will 

355 help mitigate water quantity impacts.

356 Wastewater effluent from corn starch ethanol facilities is high in BOD (Powers, 2007). 

357 For example, one report found that ethanol production from corn produces wastewater with BOD 

358 from 18,000 to 37,000 mg/L (Pimentel and Pimentel, 2008, p. 380). Ethanol wastewater effluent 

359 can also contain ammonia-nitrogen and phosphorus. 

360 Because no large-scale cellulosic ethanol production facilities are currently operating, 

361 water demand for production of cellulosic ethanol is not certain. However, for most cellulosic 

362 feedstocks, including agricultural residues like corn stover and dedicated energy crops like 

363 switchgrass, water demand is estimated to be between 2 and 10 gallons of water per gallon of 

364 ethanol, depending on the conversion technology, with volumes greater than 5 gallons of water 

365 per gallon of ethanol cited more often (NRC, 2008; Williams et al., 2009; Wu et al., 2009). Some 

366 studies assume water demand for processing woody biomass will be similar to processing 

367 cellulosic material from agricultural residues or dedicated energy crops (up to 10 gallons of 

368 water per gallon of ethanol) (Evans and Cohen, 2009). Other studies state that new technologies 

369 like fast pyrolysis will require less than half that amount of water per gallon of ethanol (Wu et 

370 al., 2009). Consumptive use of water is declining as ethanol producers increasingly incorporate 

371 recycling and other methods of converting feedstocks to fuels that reduce water use (NRC, 

372 2008). 

373 Cellulosic ethanol facilities that employ biochemical conversion would be expected to 

374 have similar water requirements and brine discharges as the current operating corn ethanol 

375 facilities. The additional steps required to separate the lignin from the cellulose could produce 

376 wastewater streams high in BOD that would require treatment onsite or at wastewater treatment 

377 plants. 

378 4.3.3.2 Distillers Grain with Solubles

379 One important co-product of ethanol production is dried distillers grain with solubles 

380 (DDGS). Due to the increase in ethanol production and the price of corn, DDGS has become an 

381 increasingly important feed component for confined livestock. About one-third of the corn 

382 processed into ethanol is converted into DDGS; therefore, approximately 45 million tons of 

383 DDGS will be produced in conjunction with the 15 billion gallons of corn ethanol produced by 

384 2015. 

385 Livestock producers may partially replace corn or other feeds with DDGS for both 

386 economic and production reasons. Different livestock species can tolerate varying amounts of 

387 DDGS in their diets. Although specific analysis of DDGS can vary among ethanol plants, DDGS 

388 are higher in crude protein (nitrogen) and three to four times higher in phosphorus compared to 

389 corn (Regassa et al., 2008). 
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390 The increase in nitrogen and phosphorus from DDGS in livestock feed has potential 

391 implications for water quality. When nitrogen and phosphorus are fed in excess of animals’ 

392 needs, excess nutrients are excreted in urine and manure. Livestock manure may be applied to 

393 crops, especially corn, as a source of nutrients. When manure is applied at rates above the 

394 nutrient needs of the crop or when the crop cannot use the nutrients, the nitrogen and phosphorus 

395 can runoff to surface waters or leach into ground waters. Excess nutrients from manure nutrients 

396 have the same impact on water quality as excess nutrients from other sources.

397 Livestock producers may limit the potential pollution from manure applications to crops 

398 through a variety of techniques. USDA’s Natural Resources Conservation Service (NRCS) has 

399 developed a standard for a comprehensive nutrient management plan to address the issue of 

400 proper use of livestock manure (NRCS, 2009). 

401 4.3.3.3 Biodiesel

402 Biodiesel facilities use much less water than ethanol facilities to produce biofuel. The 

403 primary consumptive water use at biodiesel plants is associated with washing and evaporative 

404 processes. Water use is variable, but is usually less than one gallon of water for each gallon of 

405 biodiesel produced (U.S. EPA, 2010b); some facilities recycle washwater, which reduces overall 

406 water consumption (U.S. EPA, 2010b). However, water use has been reported as high as three 

407 gallons of water per gallon of biodiesel (Pate et al., 2007). Larger well-designed facilities use 

408 water more sparingly, while smaller producers tend to use more water per production volume 

409 (U.S. EPA, 2010b). New technologies that improve water efficiency will help mitigate water 

410 quantity impacts.

411 In addition to water use in the washing and evaporation processes, other sources of 

412 wastewater include steam condensate; process water softening and treatment to eliminate 

413 calcium and magnesium salts, iron, and copper; and wastewaters from the glycerin refining 

414 process (U.S. EPA, 2008c). In a joint DOE/USDA study, it was estimated that consumptive 

415 water use at a biodiesel refinery accounts for approximately one-third of the total water use, or 

416 about 0.32 gallon of water per gallon of biodiesel produced (Sheehan et al., 1998b). New 

417 technologies have reduced the amount of wastewater generated at facilities. Process wastewater 

418 disposal practices include direct discharges (to waters of the United States), indirect discharges 

419 (to wastewater treatment plants), septic tanks, land application, and recycling (U.S. EPA, 2008c). 

420 Most biodiesel manufacturing processes result in the generation of process wastewaters 

421 with free fatty acids and glycerin (a major co-product of biodiesel production). Despite the 

422 existing commercial market for glycerin, the rapid development of the biodiesel industry has 

423 caused a glut of glycerin production, resulting in many facilities disposing glycerin. Glycerin 

424 disposal may be regulated under several EPA programs, depending on the practice. However, 

425 there have been incidences of glycerin dumping, including an incident in Missouri that resulted 

426 in a large fish kill (U.S. EPA, 2010b). 

427 Other constituents in the biodiesel manufacturing process wastewater include organic 

428 residues such as esters, soaps, inorganic acids and salts, traces of methanol, and residuals from 

429 process water softening and treatment (U.S. EPA, 2008c). Solvents used to extract lipids from 

430 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 non433 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.

4.4

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). 

454 Biofuel Distribution

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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470 Although most ethanol facilities are concentrated in the midwestern United States, 

471 gasoline consumption is highest along the east and west coasts. Fleet transport of biofuel, often 

472 by barge, rail, and truck, increases emissions of air pollutants, such as CO2, NOx, and PM due to 

473 the combustion of fuels by transport vehicles. EPA’s RFS2 RIA found relatively small increases 

474 in criteria and air toxics emissions associated with transportation of biofuel feedstocks and fuels 

475 (U.S. EPA, 2010b). In addition, transport and handling of biofuel may result in small but 

476 significant evaporative emissions of VOCs (Hess et al., 2009). With the exception of benzene 

477 emissions, which were projected to decrease slightly, EPA’s RFS2 RIA projected relatively 

478 small increases in emissions of air pollutants associated with evaporation (U.S. EPA, 2010b). 

479 Pipeline transport decreases air emissions associated with fleet transport of biofuel 

480 because fuel is not combusted in the transport process. However, transport of biofuels by 

481 pipeline raises potential technical issues, including internal corrosion and stress corrosion 

482 cracking in pipeline walls, and the potential to degrade performance of seals, gaskets, and 

483 internal coatings. Additionally, ethanol’s solvency and affinity for water can generate product 

484 contamination concerns (U.S. EPA, 2010b). Dedicated ethanol pipelines may alleviate these 

485 issues; however, they are costly to construct. Due to the incompatibility issues with the existing 

486 petroleum pipeline infrastructure, the growth in ethanol production is expected to increase 

487 emissions of criteria and toxic air pollutants from freight transport, while a corresponding 

488 decrease in gasoline distribution would decrease emissions related to pipeline pumping (Hess et al., 

489 2009). 

490 4.4.1.2 Biodiesel

491 Air pollution emissions from fuel combustion in transport vehicles related to biodiesel 

492 feedstocks and fuels are not materially different than those associated with ethanol. Currently, 

493 pipeline distribution of biodiesel is still in the experimental phase. Significant evaporative 

494 emissions are not expected from storage and transport of biodiesel fuel due to its low volatility 

495 (U.S. EPA, 2010b).

496 4.4.2 Water Quality

497 Leaks and spills from above-ground, underground, or transport tanks may occur during 

498 biofuel transport and storage, potentially contaminating ground water, surface water, or drinking 

499 water supplies. 

500 For bulk transport, the major concern is based on an accident scenario in which the 

501 transport tank is damaged and a large amount of fuel is spilled. In addition, leaks might occur 

502 during transport because of certain fuel-related factors, such as the fuel’s corrosivity. Ethanol is 

503 slightly acidic and can corrode some active metals; biodiesel is also slightly corrosive. The 

504 possibility of leaks during transport is minimized by the selection of appropriate materials and 

505 proper design in accordance with the applicable material standards.

506 Leaks from storage tanks are also a major concern. Most states report that underground 

507 storage tanks (USTs) are a major source of ground water contamination (U.S. EPA, 2000). 

508 Preliminary research has shown that any concentration of biofuel in an underground tank also 

509 containing petroleum-based fuels increases the potential for groundwater migration (EPA 
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510 OSWER Biofuels Compendium, http://www.epa.gov/oust/altfuels/bfcompend.htm). A leaking 

511 UST can also present other health and environmental risks, including the potential for fire and 

512 explosion. 

513 EPA’s Office of Underground Storage Tanks is working with other agencies to better 

514 understand material compatibility issues associated with older UST systems, in order to assess 

515 the ability of these systems to handle new fuel blends (U.S. EPA, 2009b). Because most of the 

516 current underground storage tank equipment, including 617,000 active USTs, was designed and 

517 tested for use with petroleum fuels, many UST systems currently in use may contain materials 

518 that are incompatible with ethanol blends greater than 10 percent (U.S. EPA, 2009c) or biodiesel. 

519 Although it is not possible to quantify the risk at this time, EPA is developing modeling software 

520 to assess fuels of varying composition on ground water (U.S. EPA, 2010b). 

521 Biodiesel and ethanol blend fuels degrade many non-metallic materials, such as natural 

522 rubber, polyurethane, older adhesives, certain elastomers and polymers used in flex piping, 

523 bushings, gaskets, meters, filters, and materials made of cork. Biodiesel and ethanol blend fuels 

524 also degrade soft metals such as zinc, brass, and aluminum. If a fuel system does contain these 

525 materials and users wish to fuel with blends over B20 (i.e., with fuel containing more than 20 

526 percent biodiesel), replacement with compatible elastomers is needed. In many instances, 

527 especially with older equipment, the exact composition of elastomers cannot be obtained and it is 

528 recommended they be replaced if using blends over B20. 

529 Several measures are already in place to help prevent and mitigate potential water quality 

530 impacts. Under the Resource Conservation and Recovery Act (RCRA), owners and operators of 

531 regulated UST systems must comply with requirements for financial responsibility, corrosion 

532 protection, leak detection, and spill and overfill prevention. Federal regulations require that 

533 ethanol and biodiesel storage containers are compatible with the fuel stored. For USTs, leak 

534 detection equipment is required and must be functional. Through the Spill Prevention, Control, 

535 and Countermeasure (SPCC) rule, EPA has enforceable regulations to control water quality 

536 impacts from spills or leaks of biofuel products and by-products. 

537 Further testing and certification of the acceptability of storage tanks and leak detection 

538 systems performance will be crucial to safe storage of biofuels. In addition, developing storage 

539 materials that are resistant to biofuel leaks and spills locating will help prevent spills, and 

540 locating USTs away from ground water supplies, and will mitigate water quality impacts in case 

541 a spill or leak does occur. 

542 Additional details specific to ethanol and biodiesel are discussed below. 

543 4.4.2.1 Ethanol 

544 Ethanol is stored in neat form at the production facility, in denatured form at terminals 

545 and blenders, and as E85 (85 percent ethanol and 15 percent gasoline) and E10 (10 percent 

546 ethanol and 90 percent gasoline) mixtures at retail. Ethanol is water soluble and can be degraded 

547 by microorganisms commonly present in ground water (U.S. EPA, 2009d). In ground water, 

548 ethanol’s high oxygen demand and biodegradability changes the attenuation of the constituents 

549 in gasoline/ethanol blends. This can cause reduced biodegradation of benzene, toluene, and 
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550 xylene (up to 50 percent for toluene and 95 percent for benzene) (Mackay et al., 2006; U.S. EPA, 

551 2009d). The presence of ethanol can restrict the rate and extent of biodegradation of benzene, 

552 which can cause the plumes of benzene to be longer than they would have been in the absence of 

553 ethanol (Corseuil et al., 1998; Powers et al., 2001; Ruiz-Aguilar et al., 2002). This could be a 

554 significant concern to communities that rely on ground water supplies with the potential to be 

555 impacted by leaks or spills (Powers et al., 2001; Ruiz-Aguilar et al., 2002). In surface waters, 

556 rapid biodegradation of ethanol can result in depletion of dissolved oxygen with potential 

557 mortality to aquatic life (U.S. EPA, 2010b). 

558 There are other potential hazards in addition to those associated with chemical toxicity. 

559 Some spills of gasoline with ethanol may produce methane concentrations in the soil that pose a 

560 risk of explosion (Da Silva and Alvarez, 2002; Powers et al., 2001). 

561 4.4.2.2 Biodiesel

562 In general, if biodiesel is blended with petroleum diesel, another petroleum product, or a 

563 hazardous substance, state UST regulations may apply to those blends. One-hundred percent 

564 biodiesel contains no petroleum-based products or hazardous substances. Therefore, UST 

565 regulations generally do not apply to 100 percent biodiesel.

566 Biodiesel is not water soluble. Biodiesel degrades approximately four times faster than 

567 petroleum diesel. In aquatic environments, biodiesel degrades fairly extensively (Kimble, n.d.). 

568 Results of aquatic toxicity testing of biodiesel indicate that it is less toxic than regular diesel 

569 (Kahn et al., 2007). Biodiesel does have a high oxygen demand in aquatic environments, and can 

570 cause fish kills as a result of oxygen depletion (Kimble, n.d.). Water quality impacts associated 

571 with spills at biodiesel facilities generally result from discharge of glycerin, rather than biodiesel 

572 itself (Kimble, n.d.). 

4.5

574 Most vehicles on the road today can operate on E10. Nearly half of U.S. gasoline is an 

575 E10 mixture to boost octane for more complete combustion or to meet air quality requirements 

576 (Alternative Fuels and Advanced Vehicles Data Center, 2010). E85 is another form in which 

577 ethanol is consumed, but it can only be used in flex-fuel vehicles, which can run on either 

578 conventional gasoline or ethanol blended into gasoline up to 85 percent. Under current market 

579 circumstances, greater deployment of flex-fuel vehicles may be needed to meet the EISA 

580 mandated volume standards. Because of biodiesel’s chemical properties, it is not interchangeable 

581 with petroleum-based diesel fuel. For this reason, its blend level is specifically labeled when it is 

582 blended with petroleum diesel (U.S. EPA, 2010b). Biodiesel can be used in its pure form, known 

583 as “neat biodiesel” or B100, but most vehicle and engine manufacturers do not recommend its 

584 use in non-approved engines and vehicles. There are some concerns regarding maintenance 

585 issues related to engines operated on biodiesel, because the fuel has been shown to soften and 

586 degrade certain types of elastomers and natural rubber compounds over time. This will impair 

587 fuel system components such as fuel hoses and fuel pump seals. Such component degradation 

588 can lead to leaks, poor performance, and other problems that are likely to result in increased 

589 emissions and subsequent environmental impacts. 

573 Biofuel End Use
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590 Biofuels for jet aircraft require additional refining or need to be blended with typical jet 

591 fuels to meet the standards of commercial aviation fuels. There are few long-term studies of 

592 biofuel performance on large diesel engines such as stationary power generators, ships, 

593 locomotives, and jet engines. 

594 4.5.1 Air Quality

595 The primary impact associated with biofuel end use is air quality. Section 211 (v) of the 

596 Clean Air Act requires EPA to study the air quality impacts associated with the use of biofuel 

597 and biofuel blends. EPA has already adopted mobile source emission control programs that 

598 reduce air pollution emissions and improve air quality. If necessary, EPA will issue further 

599 regulations to mitigate adverse air quality impacts as a result of increases in biofuels.

600 4.5.1.1 Ethanol 

601 The following discussion is based on E10, because considerably more information is 

602 available about its use. A wide variation in evaporative and tailpipe emissions have been 

603 reported due to a range of factors, such as the age of the vehicle, the power output and operating 

604 condition of the engine, the fuel characteristics, how the vehicle is operated, and ambient 

605 temperatures (Ginnebaugh et al., 2010; Graham et al., 2008; Yanowitz and McCormick, 2009). 

606 As stated in section 4.3.2, the emission impacts of the 2022 RFS2 volumes in the RFS2 

607 RIA were quantified relative to two reference cases: 1) the original RFS program (RFS1) 

608 mandate volume of 7.5 billion gallons of renewable fuel (6.7 billion gallons ethanol), and 2) the 

609 U.S. Department of Energy (DOE) Annual Energy Outlook (AEO) 2007 projected 2022 volume 

610 of 13.6 billion gallons of renewable fuels. In the RFS2 RIA, EPA projected decreases in 

611 emissions of carbon monoxide, benzene, and acrolein in 2022 under the RFS2-mandated 

612 volumes of biofuels, while NOx, HC, and the other air toxics, especially ethanol and 

613 acetaldehyde, were projected to increase. The inclusion of E85 emissions effects would be 

614 expected to yield larger reductions in CO, benzene, and 1,3-butadiene, but more significant 

615 increases in ethanol, acetaldehyde, and formaldehyde (U.S. EPA, 2010b). 

616 4.5.1.2 Biodiesel

617 Air emissions from combustion of some biofuels, such as ethanol, are relatively 

618 independent of feedstock or conversion process. However, biodiesel emissions may be highly 

619 variable depending on the feedstock type (Lapuerta et al., 2008; U.S. EPA, 2002). With respect 

620 to carbon content, plant-based biodiesel is slightly higher percentage-wise than animal-based 

621 biodiesel in gallon-per-gallon comparisons. For NOx, PM, and CO, plant-based biodiesel tends to 

622 have higher emissions than animal-based biodiesel for all percent blends (U.S. EPA, 2002). 

623 Studies of biodiesel and biodiesel blends show varying results depending on the fuel (i.e., 

624 type of biodiesel, biodiesel blend, type of base diesel), the vehicle being tested, and the type of 

625 testing. In general, combustion of biodiesel has been shown to decrease PM, CO, and HC 

626 emissions, increase NOx emissions, and increase ozone-forming potential (Gaffney and Marley, 

627 2009; U.S. EPA, 2002). It should be kept in mind that petroleum-based diesel-fueled vehicles are 

628 expected to emit significantly lower amounts of SO2 because of the Heavy-Duty Engine and 

629 Vehicle Standards and Highway Diesel Fuel Sulfur Control Requirements (2007 Heavy-Duty 
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630 Highway Rule) and the availability of low-sulfur diesel fuel in the marketplace, which must be 

631 accounted for when considering the emission benefits of low SOx biodiesel (U.S. EPA, 2001). 

632 Blending biodiesel in low percentages will not have much impact on sulfur emissions. 

633 With respect to carbon content, plant-based biodiesel is slightly higher than animal-based 

634 biodiesel percentage-wise. For NOx, PM, and CO, plant-based biodiesel tends to have higher 

635 emissions than animal-based biodiesel for all percent blends (U.S. EPA, 2002). 

636 EPA’s RFS2 RIA investigated the impacts of 20 volume percent biodiesel fuels on NOx, 

637 PM, HC, and CO emissions from heavy-duty diesel vehicles, compared to using 100 percent 

638 petroleum-based diesel. Average NOx emissions were found to increase 2.2 percent, while PM, 

639 HC, and CO were found to decrease 15.6 percent, 13.8 percent, and 14.1 percent, respectively, 

640 for all test cycles run on 20 volume percent soybean-based biodiesel fuel. Biodiesel results were 

641 included in the EPA analysis; however, the biodiesel contribution to overall emissions is quite 

642 small (U.S. EPA, 2010b). 
Chapter 5: International Considerations

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1 5. INTERNATIONAL CONSIDERATIONS

5.1

3 In the global context, biofuel demands from an increasing number of countries will have 

4 direct and indirect impacts, not only on countries that produce biofuels, but on countries that 

5 currently rely on imports of agricultural commodities from biofuel producers (Hertel et al., 2010; 

6 Pimentel et al., 2009; Zah and Ruddy, 2009). Section 204 of the Energy Independence and 

7 Security Act (EISA) calls for EPA to report to Congress the environmental impacts outside the 

8 United States caused by U.S. biofuel use. Thus, the following discussion focuses on potential 

9 impacts in foreign countries that may result from implementation of the RFS2 standards. 

2 Introduction

10 International trade is the primary mechanism through which foreign nations will be 

11 impacted by U.S. biofuel policy. Ethanol and, to a much smaller degree, biodiesel, have become 

12 global commodities. They are produced in many countries (Figure 5-1) and traded in 

13 international markets. Primary producers of ethanol are Brazil, the U.S., the European Union, 

14 India, and China. Brazil is the only significant exporter of ethanol (Fabiosa, 2010). Changes in 

15 U.S. production and consumption volumes, such as those in RFS2, will result in land allocation 

16 impacts that have global ramifications through international trade and market price. As a crop 

17 price rises, land will be reallocated to grow more of that crop in response to market price; 

18 conversely declining prices for a particular crop will tend to reallocate land away from that less 

19 profitable crop in favor of a more profitable one. Increased competition for arable land is 

20 expected to result in more land being allocated for crop production (Fabiosa, 2010). 

21 22 

23 Source: UNEP/GRID-Arendal, 2009.

24 Figure 5-1: Biofuel Production Map
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25 Resulting environmental impacts, both positive and negative, include effects from land 

26 use change and effects on air quality, water quality, and biodiversity. From a U.S. perspective, 

27 the severity of these impacts will depend on the volume and location of future imports and 

28 exports, both of biofuel and displaced agricultural goods. 

29 In 2008, the United States and Brazil together produced 89 percent of the world’s fuel 

30 ethanol, with the U.S. producing around 9 billion gallons (see Table 5-1) (EIA, n.d. [c]). In 2009, 

31 U.S. ethanol production increased to 10.9 billion gallons, and similar increases occurred in most 

32 ethanol-producing nations as they attempted to increase the portion of biofuel in their energy mix 

33 (EIA, n.d. [c]). As a result, total world production has nearly doubled from 10.9 billion gallons in 

34 2006 to 20.3 billion gallons in 2009. Figure 5-1 shows the geographical distribution of biofuel 

35 production. Patterns of ethanol consumption generally matched those of production, with the 

36 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)

Country/Region 2005 2006 2007 2008 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

37 Source: EIA, n.d. [c].

 38 

39 The market for the other major biofuel, biodiesel, is concentrated in Europe, which 

40 represented about 60 percent of world production as of 2009 (EIA, n.d. [b]). The other 40 percent 

41 of the market is largely made up by the United States, Brazil, Argentina, and Thailand, with U.S. 

42 production estimated at 505 million gallons for 2009, or about 10 percent of the world total (EIA, 

43 n.d. [b]). World biodiesel production has been rapidly increasing over the past decade, from 242 

44 million gallons in 2000 to about 4.7 billion gallons in 2009 (EIA, n.d. [b]). These production 

45 increases have been driven by increased consumption targets. For instance, Brazil has planned to 

46 increase its biodiesel blend from 5 to 10 percent by 2015. 
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5.2

48 U.S. biofuel import volumes will depend largely on domestic production capacity, 

49 including the efficiency of the domestic ethanol-producing sector, the yields attained, and any 

50 excess demand left to be met via imported biofuel or biofuel feedstocks. 

47 Import/Export Volumes

51 With respect to production capacity, as discussed in Chapter 2, the renewable fuel 

52 volume mandates under EISA require that U.S. biofuel consumption steadily increase to 36 

53 billion gallons by 2022. This biofuel will be comprised of both conventional and advanced 

54 biofuel (including cellulosic ethanol, algal biodiesel, and other forms of advanced biofuel). Most 

55 of the 10.9 billion gallons of conventional ethanol that the U.S. produced in 2009 came from 

56 corn starch; by 2015, this figure is expected to increase to the targeted volume provided for in the 

57 revised Renewable Fuel Standards (RFS2) program (as required under EISA) of 15 billion 

58 gallons (GAO, 2007; U.S. EPA, 2010b). Future production volumes of advanced biofuel that 

59 have not yet been commercially developed are not quite as certain. In its RFS2 Regulatory 

60 Impact Analysis (RIA), EPA estimated that cellulosic technologies could combine to provide an 

61 additional 16 billion gallons of ethanol by 2022, with a substantial portion of this, 7.8 billion 

62 gallons worth, using corn stover as a cellulosic feedstock source (U.S. EPA, 2010b). In addition, 

63 U.S. biodiesel production is projected to increase to roughly 1.3 billion gallons by 2019 (FAPRI, 

64 2010d). The RFS2 RIA also projected that the remaining 4 billion gallons needed to meet the 

65 EISA 2022 mandate would be comprised of a combination of imported sugarcane ethanol from 

66 Brazil as well as “other advanced biofuel,” including cellulosic biofuel, biomass-based diesel, 

67 and co-processed renewable diesel (U.S. EPA, 2010b). Table 5-2 shows the projected import 

68 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 2016 2017 2018 2019 2020 2021 2022

U.S. Corn 

Ethanol 

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

69 Source: U.S. EPA, 2010b, pp. 77-78. 

70 Figures are in millions of gallons.

71 As Table 5-2 shows, import volumes will be at or below 200 million gallons in years 

72 preceding 2015, followed by a significant increase in import volumes between 2015 and 2022. 

73 This is in part because domestic corn starch ethanol production is expected to increase rapidly up 

74 until 2015 and then level off, and also because the RFS2 total renewable fuel requirements 

75 increase more rapidly in the later years. It should also be noted that 2010 import figures have 

76 been much lower than those expected when forecasts were made in 2009. Imports of fuel ethanol 

77 for the first three-quarters of 2010 (USDA, n.d.) have totaled 17 million gallons –well below 

78 EPA’s 200 million gallons forecast (EPA, 2010b). Therefore, ethanol imports may be 

79 significantly lower than the projections in Table 5-2. U.S. biofuel imports and exports will also 

80 be influenced by trade policy, including tariffs and other incentives in the U.S. and in other 

81 countries. Even if the U.S. succeeds in meeting the RFS2 targets, the U.S. likely will continue to 

82 import and export biofuel as individual producers take advantage of international price 
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83 differences. Over the past decade (2002 to 2009), U.S. ethanol import quantities varied 

84 considerably (see Table 5-3) , mostly due to volatility in the prices of related commodities such 

85 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 2006 2007 2008 2009

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

86 Source: EIA, n.d. [c] for production figures; EIA, n.d. [d] for import figures.

87 Note: Figures are in millions of gallons.

 88 

89 The bulk of U.S. ethanol imports are sugarcane-based ethanol from Brazil. In 2008, the 

90 U.S. was the largest importer of Brazilian ethanol, followed by the Netherlands and a number of 

91 Caribbean countries (see Table 5-4). However, foreign-produced ethanol is also imported to the 

92 U.S. via these Caribbean countries where the Caribbean Basin Initiative (CBI), a regional trade 

93 agreement, enables up to 7 percent of the biofuel consumed in the U.S. to be imported from CBI 

94 member countries duty-free (Yacobucci, 2005; Farinelli et al., 2009). Therefore, most of the 

95 Brazilian exports shown as going to CBI member countries such as Costa Rica, Jamaica, El 

96 Salvador, Trinidad and Tobago, (see Table 5-4), is eventually re-exported to the United States. 

97 Looking closer at these Brazilian export figures in Table 5-4, it is evident that ethanol trade 

98 changed somewhat dramatically in 2009, with most destinations experiencing a significant 

99 decline in imports. A large part of this decline is due to the drop in U.S. imports caused by a 

100 change in energy prices, as well an increase in sugar prices that made imported Brazilian ethanol 

101 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

Destination Country

Volume (million gallons)

2008 % of Total 2009 % of Total

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%

102 Source: SECEX, n.d.

103 Note: Percentages do not sum to 100 percent because some destinations are not listed. Original data were 

104 converted from liters to gallons. 
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105 well as the recent strengthening of Brazil’s currency, could significantly hinder Brazil’s ability to 

106 supply the U.S. market moving forward. Even if the 54-cent-per-gallon tariff on ethanol imports 

107 does expire as planned at the end of 2010, these factors may limit future imports (USDA, 

108 2010d). 

109 The U.S. also exports biofuel (including ethanol and biodiesel) to foreign countries. 

110 Canada has been the primary recipient of U.S. exports, with Europe becoming a more prevalent 

111 destination beginning in 2004 (see Figure 5-2) as its biofuel consumption has increased. U.S. 

112 ethanol exports have increased in recent years due to increased production. However, export 

113 levels, ranging from about 50 million to 175 million gallons, are no more than 1 percent of 

114 domestic production and are far outweighed by imports. Exports are likely to continue to lag 

115 behind imports in the near-term as consumption rises. 

116 

117 Source: ERS, 2010a. 

118 Note: Original data were converted from liters to gallons, graph was created by ERG. 119 

120 Figure 5-2: Historic U.S. Ethanol Export Volumes and Destinations

121 Table 5-5 shows the 2008 U.S. biodiesel trade balance. At that time, 46.8 percent of 

122 domestically produced biodiesel was exported. Biodiesel export volume has increased 

123 dramatically in recent years, from about 9 million gallons in 2005 to nearly 677 million in 2008 

124 (EIA, n.d.[b]). In 2009, biodiesel export volume fell dramatically to only 266 million gallons 

125 (USDA, n.d.). Current projections have net U.S. biodiesel exports (i.e., exports minus imports) 

126 falling for the next few years and then rising back up to around 100 million gallons by the end of 

127 the decade (FAPRI, 2010d). 

128 

0

20

40

60

80

100

120

140

160

180

200

2000/01 2001/02 2002/03 2003/04 2004/05 2005/06 2006/07 2007/08 2008/09

Harvest Year

Million Gallons

Other

UAE

India

Austrailia

EU

Mexico

Canada
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Table 5-5: 2008 U.S. Biodiesel Balance of Trade

Item Quantity

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

129 Source: EIA, 2009, n.d.[c]. 

5.3

131 The issue of land use change inherently includes international considerations, as the 

132 demand for biofuel in the U.S. can influence the international availability of crops such as corn 

133 and soybeans for both biofuel and agricultural markets, which in turn can incentivize land use 

134 changes in other countries to meet that demand. In this report, land use is defined as “the human 

135 use of land involving the management and modification of natural environment or wilderness 

136 into built environment such as fields, pastures, and settlements”. Land use changes are 

137 considered either direct or indirect. In the context of biofuels, direct land use change (DLUC)

138 refers to land conversion that is directly related to the biofuel supply chain. An example of direct 

139 land use change would be the planting of sugarcane on Brazilian land, which was previously 

140 native forest or used for another non-biofuel crop, for the purpose of increasing the supply of 

141 ethanol to export to the United States. Indirect land use change (ILUC) refers to land conversion 

142 that is a market-oriented response to changes in the supply and demand of goods that arise from 

143 increased production of biofuel feedstocks. An example of indirect land use change would be the 

144 clearing of foreign land to plant corn in response to reduced U.S. corn exports caused by 

145 increased U.S. corn ethanol production. Some have argued that these indirect impacts should not 

146 be counted as part of the biofuel carbon footprint because they are too difficult to relate back to 

147 biofuel production. However, EISA requires that “direct emissions and significant indirect 

148 emissions such as significant emissions from land use change” be considered as part of the 

149 analysis of environmental impacts stemming from domestic biofuel production and consumption. 

130 Environmental Impacts of Direct and Indirect Land Use Changes

150 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

 

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.

151 This model predicts 

152 world prices by equating excess supply and demand across countries. Changes in world prices 

153 determine changes in worldwide commodity production and trade. Under this model, two 

154 primary domestic effects directly affect a commodity’s worldwide use and trade: change in U.S. 

155 exports and changes in domestic U.S. prices (U.S. EPA, 2010b). Using this model, along with 

156 MODIS satellite data and other models, the RIA analysis compares 2022 crop area and 

157 production (by crop type and country) predicted to result with and without (i.e., “business as 

158 usual”) EISA requirements. The results of this analysis are shown in Figures 5-3, 5-4, 5-5, and 
Chapter 5: International Considerations

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159 5-6 and in Table 5-6. In Figures 5-3, 5-4, 5-5, and 5-6, each column shows the marginal impact 

160 of a scenario that focuses on that particular feedstock in isolation.

161 The model forecasts that, by 2022, for every increase of 1,000 gallons of corn starch 

162 ethanol production in the U.S., corn exports will have decreased by 4 tons. Similarly, for every 

163 increase of 1,000 gallons of soybean-based biodiesel produced domestically, soybean oil exports 

164 will have decreased by just over 2 tons (see Figure 5-3) (U.S. EPA, 2010b). Thus, as the U.S. 

165 increases domestic production of corn starch ethanol and soybean diesel, exports of corn and 

166 soybean for agricultural or other uses are expected to decline, which may result in indirect land 

167 use change in the form of land conversion to agriculture in other countries. This result is 

168 consistent with the results of a 2009 study, which predicted that due to production increases 

169 required by EISA, U.S. coarse grain exports will decrease to all destinations and this will cause

170 dominant export competitors and trading partners, likely in Latin America, China, and the Pacific 

171 Rim, to convert more of their lands to make up the difference (Hertel et al., 2010; Keeney and 

172 Hertel, 2009). However, given that RFS2 limits the amount of corn starch ethanol that can be 

173 counted toward the mandated volume targets at 15 billion gallons─a level the U.S. is expected to 

174 reach by 2015 or sooner (GAO, 2007; U.S. EPA, 2010b), indirect land use change impacts 

175 resulting from changing trade patterns of corn and other grains may level off at that point. In 

176 fact, U.S. biofuel consumption could decrease pressure on conversion of land to agricultural use 

177 if agricultural yield improvements occur or if cellulosic technologies develop to replace 

178 conventional ethanol production. 

179 

180 Source: U.S. EPA, 2010b.

181 Figure 5-3: Change in U.S. Exports by Crop Anticipated to Result from EISA 

182 Requirements by 2022 (tons per 1,000 gallons of renewable fuel) 
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183 The model also predicts that the additional biofuel produced to meet the EISA mandates 

184 compared to “business as usual” (2.7 billion gallons of corn starch ethanol, 7.9 billion gallons of 

185 switchgrass cellulosic ethanol, 1.6 billion gallons of imported sugarcane ethanol, and 0.5 billion 

186 gallons of soybean biodiesel) will lead to the creation of 2 million acres, 3.4 million acres, 1.1 

187 million acres, and 1.7 million acres, respectively, of additional international cropland (see Table 

188 5-6) to supply U.S. biofuel imports and also to make up for the U.S. reductions in exports shown 

189 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

190 Source: U.S. EPA, 2010b.

191 Note: Figures converted from hectare to acre

192 Further, these direct and indirect land use changes will lead to significant GHG emissions 

193 according to the model (before accounting for GHG savings resulting from petroleum displaced 

194 as the biofuel is consumed). Figure 5-4 shows that, based on the model presented in the RIA, 

195 soy-based biodiesel causes the largest release of international land use change GHG 

196 emissions. The majority of international land use change emissions originate in Brazil in the corn 

197 ethanol and switchgrass ethanol scenarios. This is largely a consequence of projected pasture 

198 expansion in Brazil, and especially in the Amazon region where land clearing causes substantial 

199 

200 Source: U.S. EPA, 2010b.

201 Figure 5-4: International Land Use Change GHG Emissions by Renewable Fuel

202 Anticipated to Result from EISA Requirements by 2022 (kgCO2e/mmBTU)
Chapter 5: International Considerations

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Source: U.S. EPA, 2010b.

228 

229 

Figure 5-5: Harvested Crop Area Changes by Region Anticipated to Result from EISA 

Requirements by 2022, 2022 (ha / billion BTU)

230 

231 

203 GHG emissions. Of the renewable fuels analyzed, the model found that sugarcane ethanol causes 

204 

205 

206 

207 

208 

209 

210 

211 

212 

213 

214 

215 

216 

217 

218 

219 

220 

221 

222 

223 

224 

225 

226 

227 

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. 
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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 

di

and

ffe

 w

rin

h

g opinions on the result of this tradeoff and it is not possible at this time to predict with 

any cert

at its

ainty w

 env

hat

ir

 t

o

y

nm

pe o

ental

f land use change will result from increased U.S. demand for biofuel 

consequences will be (Fargione et al., 2008; Goldemberg et al., 

2008; Searchinger et al., 2008). A recent study (Fabiosa et al., 2010) suggests that sugarcanebased 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).

232 

233 

234 

235 

236 

237 

238 

239 

240 

241 

242 

243 

244 

245 

246 

247 

248 

249 

250 

Source: U.S. EPA, 2010b.

251 

252 

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 

253 

254 

256 

257 

258 

255 
Chapter 5: International Considerations

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259 as other energy sources such as fossil fuels, wind, and solar, an increase in biofuel crop 

260 production could further strain global supplies of water (Gerbens-Leenes et al., 2008). Studies 

261 have shown that water tables are already declining in the western United States, North India, 

262 Pakistan, North China, Mexico, and the Mediterranean (Shah et al., 2007). These trends indicate 

263 the vulnerability of various regions to water scarcity issues. The choice of feedstock, cultivation 

264 practices, and the location of cultivation will greatly influence how production of biofuel impacts 

265 water availability.

266 Water quality and flooding issues are also relevant. As described in Chapter 3, U.S. corn 

267 production has been a key driver of hypoxia in the Gulf of Mexico. Similar water quality issues 

268 could arise or be exacerbated in other countries if agricultural use from feedstock production 

269 expands. Conversion of land to feedstock production will have varying impacts, depending on 

270 prior ecological function of the converted land and the types of management practices employed. 

271 Impacts could include encroachment on wetlands and the discharge of excess nutrients to water 

272 resources. For example, Brazilian surface waters suffered from hypoxia during the early stages 

273 of their biofuel development when the vinasse, a by-product of the sugarcane-ethanol production 

274 process rich in nitrogen and potassium, was routinely discarded into rivers, lakes, and reservoirs, 

275 causing extensive eutrophication (Simpson et al., 2009). Brazilian federal law has prohibited the 

276 dumping of vinasse into any water body since 1978. The effluent is now returned to the field as 

277 fertilizer, and water quality has improved significantly. However, if other developing countries 

278 opt to produce biofuel and do not properly regulate water quality impacts, eutrophication could 

279 damage these nations’ aquatic ecosystems. Also, if biofuel-related land use change does occur 

280 and if it results in deforestation and loss of wetlands, then increased flooding, sedimentation, and 

281 lower stream base flows are also likely to occur. Examples of this have already been seen around 

282 the world. For instance, in Southeast Asia, tropical peat swamps have been degraded because of 

283 loss of forest cover due to logging for timber and conversion of forests to oil-palm plantations for 

284 biofuel (Wösten et al., 2006). However, biofuel production was not the only cause of land 

285 conversion, and it is possible that food-related demands for palm oil would have caused similar 

286 deforestation. 

287 Biofuel production also affects international air quality. While the displacement of 

288 petroleum fuels by biofuels does have a positive impact, the air quality issues associated with 

289 biofuel feedstock harvesting, refining, and transport could erode these savings if poor 

290 management practices are allowed to occur. For instance, the practice of burning sugarcane 

291 fields prior to harvesting is a serious air pollution issue in Brazil. This method has resulted in 

292 large aerosol and trace gas emissions, significant effects on the composition and acidity of 

293 rainwater over large areas of southern regions, and elevated ozone levels in those areas affected 

294 by the burning. However, harvest burning practices are being phased out in Brazil through state 

295 regulations. In 2007, state laws ensured that 40 percent of the sugarcane was harvested without 

296 burning in the state of Sao Paulo, and this is forecast to reach 50 percent by 2010 and about 90 

297 percent by 2022 (Goldemberg et al., 2008; U.S. EPA, 2010b). Like many of the effects discussed 

298 so far, the severity of air emissions will be highly sensitive to the feedstock chosen, location of 

299 production, and management practices.

300 Finally, if increased biofuel consumption in the U.S. does lead to indirect land use 

301 changes and more natural habitat is cleared to create agricultural lands, a loss of biodiversity will 

302 occur. Many biofuel production regions coincide with areas with high biodiversity value. For 
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303 example, Indonesia (palm oil), Malaysia (palm oil), and Brazil (sugar ethanol) all contain 

304 ecosystems with well above average biodiversity. Depending where biofuel feedstock production 

305 occurs, and the manner in which it occurs, impacts to biodiversity could be significant.

5.5

307 Projections indicate that the EISA biofuel targets will likely alter U.S. and international 

308 trade patterns. How countries respond to U.S. market conditions could affect net GHG savings 

309 derived from biofuel consumption and the environmental impacts that result from biofuel 

310 production. As with biofuel production in the U.S., these impacts will depend largely on where 

311 the crops are grown and what agricultural practices are used to grow them. To the extent that 

312 local environmental impacts will have broader implications, such as contributing to global 

313 warming, global mitigation strategies will have to consider the international implications of 

314 biofuel production. Decisions made about what feedstocks to use, where to produce them, and 

315 what production methods to employ will have significant environmental and economic 

316 implications.

306 Concluding Remarks

 317 
Chapter 6: Conclusions and Recommendations 

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1 6. CONCLUSIONS AND RECOMMENDATIONS

6.1

3 A variety of factors make it difficult to draw conclusions about the potential 

4 environmental and resource conservation impacts of the increased biofuel production and use 

5 mandated by the Energy Independence and Security Act. Of the six feedstocks discussed in this 

6 Report, only corn starch and soybean have been implemented at commercial scale to produce 

7 ethanol and biodiesel, respectively. Production of biofuel from the other four feedstocks 

8 discussed in this report is in various stages of research and development. Even for corn starch 

9 and soybean, data needed to perform a thorough environmental life cycle assessment are 

10 incomplete and the relevant available data often have a high degree of uncertainty. Nevertheless, 

11 initial conclusions can be drawn about how increased biofuel production and use likely will 

12 affect (or is affecting, in the case of corn starch and soybean) water quality and quantity, soil and 

13 air quality, and ecosystems (biodiversity and invasive species) based on the data available as of 

14 July 2010. These conclusions are presented below for the full greenhouse gas (GHG biofuel life 

15 cycle (Section 6.1.1) and for stages in the life cycle: feedstock production (Section 6.1.2); biofuel 

16 production, transport, and storage (Section 6.1.3); and biofuel end use (Section 6.1.4). (See 

17 Figure 2-3 in Chapter 2 for life cycle description.) These conclusions do not account for existing 

18 or potential future mitigation measures or regulations.

2 Conclusions

19 6.1.1 Emissions Reduction

20 Fuel combustion at ethanol and biodiesel facilities releases GHGs. However, when the 

21 entire biofuel life cycle is considered (as described in Chapter 4, Section 4.3.2.3), the revisions to 

22 the Renewable Fuel Standard (RFS2) program mandated by the Energy Independence and 

23 Security Act (EISA) are expected to achieve a 138-million metric ton reduction in CO2-

24 equivalent emissions by 2022. 

25 6.1.2 Feedstock Production 

26 6.1.2.1 Overview

27 Figure 6-1 provides a qualitative overview, based on EPA’s best professional judgment, 

28 of the maximum potential range of domestic environmental and resource conservation impacts 

29 associated with per unit area production of the six feedstocks discussed in this Report. 

30 Qualitative assessment is grounded in information and data published in the peer-reviewed 

31 literature through July 2010, which are described in Chapter 3. Range extremes for each impact 

32 category were determined by considering plausible conditions under which a “most negative” 

33 and “most positive” environmental impact would likely arise. Key assumptions for these 

34 conditions appear in Figure 6-1; for full, detailed elaboration of the conditions, which encompass 

35 a variety of factors, including land use, feedstock production management choices, region, 

36 technology used, regulatory control, and mitigation measures, see Appendix C, Table C-1. 
Chapter 6: Conclusions and Recommendations 

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37 

Magnitude Certainty 

(length of bar) Negative effects Negligible effect Positive effects (shading)

Relatively large Least certain

Moderate Moderately certain

Relatively minor Most certain

 Type of Effects 

Legend

38 

39 Figure 6-1: Maximum Potential Range of Environmental Impacts (on a Per Unit Area 

40 Basis) Resulting from Cultivation and Harvesting of the Six Biofuel Feedstocks 

41 Considered in This Report

Water Quality (3.2.2) Conventionally managed corn 

replaces CRP

Diversion of existing corn production 

to fuel

Water Quantity (3.2.3) Irrigated (irr.) corn replaces non-irr. 

land Production of non-irr. corn

Soil Quality (3.2.4) Conventionally managed corn 

replaces CRP

Diversion of existing corn production 

to fuel

Air Quality (3.2.5) Irrigated corn replaces non-irrigated 

land

Diversion of existing corn production 

to fuel

Biodiversity (3.2.6.1) Conventionally managed corn 

replaces CRP

Diversion of existing corn production 

to fuel

Invasiveness (3.2.6.2)

Water Quality (3.2.2) Soy replaces CRP Soy replaces corn

Water Quantity (3.2.3) Irr. soy replaces non-irr. land Non-irr. soy replaces irr. corn

Soil Quality (3.2.4) Soy replaces CRP Soy replaces corn

Air Quality (3.2.5) Irr. soy replaces non-irr. land Non-irr. soy replaces irr. corn

Biodiversity (3.2.6.1) Soy replaces CRP Soy replaces corn

Invasiveness (3.2.6.2)

Water Quality (3.2.2) High removal on erodible land Site-specific removal to minimize 

erosion

Water Quantity (3.2.3) High removal on irr. land Site-specific removal to minimize 

need for irrigation

Soil Quality (3.2.4) High removal on erodible land Site-specific removal to minimize 

erosion

Air Quality (3.2.5) Extra harvesting pass required Single-pass harvest with grain

Biodiversity (3.2.6.1) High removal on erodible land Site-specific removal to minimize 

erosion

Invasiveness (3.2.6.2)

Water Quality (3.4.2) Short interval woody crop replaces 

mature plantation

Long interval woody crop replaces 

short interval plantation

Water Quantity (3.4.3) SRWC that is irrigated Thinning or non-irr. woody crop

Soil Quality (3.4.4) Short interval woody crop replaces 

mature plantation

Long interval woody crop replaces 

short interval plantation

Air Quality (3.4.5) See "Water Quality" + woody crop 

emits isoprene

See "Water Quality" + woody crop 

with low isoprene emissions

Biodiversity (3.4.6.1) Short interval woody crop replaces 

mature plantation

Long interval woody crop replaces 

short interval plantation

Invasiveness (3.4.6.2) Woody crop (ex. Eucaluptus ) 

invades Non-invasive woody crop used

Water Quality (3.3.2) Conventionally managed grass 

replaces CRP

Conservation managed grass 

replaces conventional corn

Water Quantity (3.3.3) Irr. grass replaces non-irr. land use Non-irr. grass replaces irr. corn

Soil Quality (3.3.4) Conventionally managed grass 

replaces CRP

Conservation managed grass 

replaces conventional corn

Air Quality (3.3.5) Irr. grass replaces non-irr. land use Conservation managed, non-irr. 

grass replaces irr. corn

Biodiversity (3.3.6.1) Uniformly managed grass replaces 

CRP

Diversely managed grass replaces 

conventional corn

Invasiveness (3.3.6.2) Non-native grasses invade Non-invasive grasses used

Water Quality (3.5.2) Untreated effluent is discharged Grown with wastewater

Water Quantity (3.5.3) Freshwater, open pond in dry region Recycled wastewater, closed 

bioreactor

Soil Quality (3.5.4)

Air Quality (3.5.5) Manufactured nutrients added Wastewater nutrients used

Biodiversity (3.5.6.1)

Invasiveness (3.5.6.2) Algae in open ponds invade Non-invasive algae in closed 

bioreactors

Maximum Potential 

Negative Environmental 

Impact

Negligible known impact

Negligible known impact

1

 Bars are conditioned on key assumptions described briefly here and fully elaborated in Appendix C, Table C-1.

Negligible known impact

Negligible known impact

Impact Category 

(Report Section)

Key Assumptions1

Maximum Potential 

Positive Environmental 

Impact

Negligible known impact

Maximum Potential 

Range of Environmental 

Impacts per Unit Area1

Corn (Starch) Corn Stover Woody Biomass Perennial Grasses Algae Soybean
Chapter 6: Conclusions and Recommendations 

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42 Impacts shown in this figure are only relative to each other. No attempt has been made to 

43 compare impacts to those of petroleum production, nor do impacts represent possible 

44 environmental benefits gained by petroleum displacement. In addition, impacts are only relevant 

45 for those regions where each feedstock is likely to be grown (see Chapter 3). Impacts for corn 

46 stover do not include the impacts of corn production itself but rather impacts of stover removal 

47 above and beyond corn cultivation and harvest. Air quality impacts do not include changes in 

48 GHG emissions.

49 Bar direction signifies whether the effect is negative (left) or positive (right). Bar length

50 indicates the anticipated magnitude of effect, and shading density depicts the associated degree 

51 of certainty. A circle signifies that no net effect is anticipated. Section numbers next to the 

52 impact category indicate where in this Report the information that provides the basis for the bars

53 in this figure can be found. 

54 When the potential range of production conditions is considered, four feedstocks 

55 (soybean, woody biomass, perennial grasses, and algae) are anticipated to have both negative and 

56 positive environmental impacts. The most positive environmental outcome for corn starch and 

57 corn stover is no net effect, achieved largely through minimization of land use change and 

58 through site-specific agricultural management, including comprehensive conservation practices. 

59 Most feedstocks (corn starch, soybean, corn stover, woody biomass, and perennial grasses) have 

60 the potential to have impacts in at least five of the six environmental categories shown in the 

61 figure; algae are anticipated to have impacts in only four of the categories (water quality, water 

62 quantity, air quality and invasiveness). A higher degree of certainty is associated with the two 

63 feedstocks that are already commercially produced (corn starch and soybean) than with those in 

64 development (corn stover, woody biomass, perennial grasses, and algae).

65 6.1.2.2 Conclusions

66 Key conclusions concerning environmental impacts of biofuel feedstock cultivation are 

67 as follows: 

68 Water Quality. Increased cultivation of feedstocks for biofuel may affect water quality

69 and hypoxia conditions in the Gulf of Mexico and other vulnerable water bodies through 

70 increased erosion and runoff and leaching of fertilizers and pesticides to ground and surface 

71 waters. Cellulosic feedstocks may have less water quality impact than corn starch and corn 

72 stover due to projected decreased fertilizer use and decreased soil erosion. Comprehensive 

73 management systems and practices are one tool that may mitigate some of these impacts if they 

74 are widely and effectively implemented. Compared to corn and soybeans, cultivation of some 

75 cellulosic feedstocks may provide benefits, including soil stabilization, reduced soil erosion and 

76 nutrient runoff, and increased nutrient filtration. 

77 Water Quantity. Effects of feedstock production on water availability vary greatly by 

78 feedstock, processes used to produce the feedstock, and location. Corn and soybean cultivation 

79 for biofuel production have a greater water demand than perennial grasses, woody biomass, and 

80 algae. Regional differences are mostly due to precipitation which, when insufficient, necessitates 

81 supplemental irrigation, which can be a significant water use in the biofuel production process. 

82 In irrigated regions, the method and efficiency of irrigation can also affect the amount of water 
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83 used. For both corn and soybeans, the source for irrigation water varies from region to region, 

84 potentially affecting water tables and/or surface waters. Removal of corn stover can reduce soil 

85 moisture, resulting in a need for increased irrigation. Water quantity effects may be mitigated by 

86 growing feedstocks in areas that do not require irrigation and by using efficient irrigation 

87 practices, such as reclaimed water use.

88 Soil Quality. Increased cultivation of corn, soybean, woody biomass, and perennial 

89 grasses will affect soil quality in various ways, depending on the feedstock. Effects include 

90 increased soil erosion, decreased soil organic matter content, increased soil GHG emissions, and 

91 increased nitrogen and phosphorus losses to ground and surface waters. Annual crops, such as 

92 soybean and corn, will have higher erosion rates than non-row crops, such as perennial grasses 

93 and woody biomass. However, cultivation of corn or soybean at higher rates (i.e., greater yield 

94 per acre) on existing corn or soybean acreage likely will not alter soil erosion rates significantly. 

95 Soil quality impacts from biofuel feedstocks may be ameliorated by the choice of feedstock and 

96 by the diligent use of generally accepted conservation practices.

97 Air Quality. Activities associated with growing biofuel feedstocks emit air pollutants, 

98 which affect air quality, with effects varying by region. Production of row crops will affect air 

99 quality more than non-row crops. Pollutants from row crops include farm equipment emissions 

100 and soil and related dust particles (e.g., fertilizer, pesticide, and manure) made airborne as a 

101 result of field tillage and fertilizer application, especially in drier areas of the country. 

102 Biodiversity. Increased cultivation of corn and soy feedstocks could significantly affect 

103 biodiversity (1) through habitat alteration when uncultivated land is moved into production, and 

104 (2) from exposure of flora and fauna to high pesticides concentrations. Aquatic habitat may be 

105 impaired by soil erosion and nutrient runoff. Biodiversity impacts can be mitigated by choosing 

106 crop and cultivation methods that minimize habitat alteration and runoff. 

107 Invasiveness. Corn and soybean pose little risk of becoming weedy or invasive in the 

108 U.S. In certain regions, some perennial grasses, short-rotation woody crops, and algae strains 

109 pose greater, though uncertain, risk of becoming an agricultural weed or invasive in natural 

110 areas. Transport of grass and short-rotation woody crop seeds and plant parts capable of 

111 vegetative reproduction from the field to biofuel production facilities may increase the 

112 opportunity for seeds and plant parts capable of vegetative reproduction to establish themselves 

113 in feral populations along transportation corridors. Algae produced in photo-bioreactors are less 

114 likely to become invasive than algae produced in open ponds.

115 6.1.3 Biofuel Production, Transport, and Storage 

116 As described below, biofuel production, transport, and storage can impact water quality, 

117 water quantity, and air quality.

118 6.1.3.1 Overview

119 Figure 6-2 provides a qualitative overview, based on EPA’s best professional judgment, 

120 of the maximum potential range of domestic environmental and resource conservation impacts 

121 associated with per unit volume production, transport, and storage of ethanol from corn and 

122 cellulosic feedstocks and biodiesel from soybean (though biodiesel from algae should not be 
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123 appreciably different). Qualitative assessment is grounded in information and data published in 

124 the peer-reviewed literature through July 2010, which are described in Chapter 4. As with Figure 

125 6-1, range extremes for each impact category were determined by considering plausible 

126 conditions under which a “most negative” and “most positive” environmental impact would 

127 likely arise. Key assumptions for these conditions appear in Figure 6-2; for full, detailed 

128 elaboration of the conditions, which encompass a variety of factors, including region, technology 

129 used, regulatory control, and mitigation measures, see Appendix C, Table C-2. 

130 Impacts shown in this figure are only relative to each other. No attempt has been made to 

131 compare impacts to those of petroleum production, nor do impacts represent possible 

132 environmental benefits gained by petroleum displacement. 

133 Bar conventions used in Figure 6-1 are the same as those used in Figure 6-2. 

134 As Figure 6-2 illustrates, the environmental impacts of biofuel production, transport, and 

135 storage are expected to be largely negative (see Chapter 4 for more details). However, for all 

136 three fuel types, impacts can be minimized through appropriate facility siting, waste treatment, 

137 and improved, more efficient technology. 

138 Water Quality. Pollutants in the wastewater discharged from biofuel production impact 

139 water quality. Biological oxygen demand (BOD), brine, ammonia-nitrogen, and phosphorus are 

140 primary pollutants of concern from ethanol facilities. BOD, total suspended solids, and glycerin 

141 pose the major water quality concerns in biodiesel facility effluent. Actual impacts depend on a 

142 range of factors, including the type of feedstock processed, biorefinery technology, effluent 

143 controls, and water re-use/recycling practices, as well as the facility location and source and 

144 receiving water.

145 Water Quantity. Biofuel production facilities draw on local water supplies to produce 

146 fuel, but the quantity of water used is modest compared to that required to produce biofuel 

147 feedstocks. Impacts will depend on the location of the facility in relation to water resources. 

148 Water availability issues can be mitigated by siting production facilities where water is abundant. 

149 Air Quality. Emissions from biofuel production facilities are generated primarily by the 

150 stationary combustion equipment used for energy production. Compared to two scenarios ([1]

151 the original renewable fuel standard of 7.5 billion gallons, and [2] a 2022 renewable fuel volume 

152 of 13.6 billion gallons projected by the Department of Energy’s 2007Annual Energy Outlook), 

153 RFS2-mandated increased biofuel production will likely result in decreased emissions of carbon 

154 monoxide and benzene, and increased emissions of nitrogen oxides, volatile organic compounds, 

155 particulate matter, and several air toxics. Since biofuel production facilities are regulated under 

156 the Clean Air Act and subject to state/local permits, enforcement of existing regulations will 

157 mitigate air quality impacts. Emissions can be further reduced through use of cleaner fuels (e.g., 

158 natural gas instead of coal) and more efficient process and energy generation equipment. 
Chapter 6: Conclusions and Recommendations 

159 

 160 

161 

Impact Category

(Report section)

Water Quality 

(4.4.2, 4.6.2)

High BOD effluent; DDG byproduct 

fed to livestock with poor waste 

management; underground storage 

tanks (USTs) leak

Effluent treated; DDG-fed 

livestock waste managed; 

USTs do not leak

Water Quantity 

(4.3.3)

3-6 gallons water/gallon 

ethanol Improved water use efficiency

Air Quality3 

(4.3.2, 4.4.1, 4.5.1, 4.6.1) Ethanol facility coal-powered Ethanol facility natural gaspowered

Water Quality 

(4.4.2, 4.6.2)

High BOD, total suspended 

solids (TSS), glycerin effluent Effluent treated

Water Quantity 

(4.3.3)

<1 gallon water/gallon 

biodiesel

<1 gallon water/gallon 

biodiesel

Air Quality3 

(4.3.2, 4.4.1, 4.5.1, 4.6.1) Biodiesel facility coal-powered Biodiesel facility natural gaspowered

Water Quality 

(4.4.2, 4.6.2) High BOD effluent; USTs leak Effluent treated; USTs do not 

leak

Water Quantity 

(4.3.3)

10 gallons of water/gallon 

cellulosic ethanol Improved water use efficiency

Air Quality3 

(4.3.2, 4.4.1, 4.5.1, 4.6.1) Ethanol facility coal-powered Ethanol facility natural gaspowered

2

Comparisons are made on the basis of equal volumes of the biofuels indicated.

3

Impacts shown are immediate impacts from biofuel production to end use. No attempt is made in this table 

to represent air quality impacts based on displaced gasoline emissions. See Section 4.5 for more information.

Key Assumptions1

Maximum Potential 

Negative Environmental 

Impact

Maximum Potential 

Positive Environmental 

Impact

1

 Bars are conditioned on key assumptions described briefly here and fully elaborated in Appendix C, Table C-2. Corn Ethanol Cellulosic Ethanol Soybean Biodiesel

Maximum Potential 

Range of Environmental 

Impacts per Unit 

Volume1,2

Legend

Magnitude Certainty 

(length of bar) Negative effects Negligible effect Positive effects (shading)

Relatively large Least certain

Moderate Moderately certain

Relatively minor Most certain

 Type of Effects 

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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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164 6.1.3.2 Biofuel Transport and Storage 

165 Biofuel transport and storage may impact water and air quality. 

166 Water Quality. Leaks and spills of biofuel from above-ground, underground, and

167 transport tanks can potentially contaminate ground, surface, and drinking water. A leaking 

168 underground storage tank can also present other health and environmental risks, including the 

169 potential for fire and explosion. Enforcement of existing regulations concerning corrosion 

170 protection, leak detection, and spill and overfill prevention will minimize water contamination. 

171 Selection and use of appropriate materials and proper design in accordance with the applicable 

172 material standards will also prevent biofuel leaks. 

173 Air Quality. Air quality will be affected by emissions from biofuel transport via rail, 

174 barge and tank truck and by evaporative, spillage, and permeation emissions from transfer and 

175 storage activities. However, the impacts are not expected to be significant. 

176 6.1.4 Biofuel End Use 

177 Air Quality. Evaporative and tailpipe emissions from biofuel combustion show great 

178 variability due to a range of factors, including the vehicle age, how the vehicle is operated, and 

179 ambient temperatures. Emissions in 2022 are expected to be higher for some pollutants and 

180 lower for others compared to two scenarios (described in 6.1.3.1). In general, biodiesel 

181 combustion has been shown to decrease particulate matter, carbon monoxide, and hydrocarbon 

182 emissions, increase nitrogen oxide emissions, and increase ozone-forming potential compared to 

183 fossil fuel diesel. Emissions from ethanol use are independent of feedstock; in contrast, 

184 emissions from biodiesel use differ according to the feedstock. Particulate matter, nitrous oxide, 

185 and carbon monoxide emissions are higher for plant-based biodiesel than for animal-based 

186 biodiesel.

187 6.1.5 International Considerations 

188 Increases in U.S. biofuel production and consumption volumes will affect many different 

189 countries as trade patterns and prices adjust to equate global supply and demand. This will result 

190 in environmental impacts, both positive and negative, including effects from land use change and 

191 effects on air quality, water quality, and biodiversity. Direct and indirect land use changes will 

192 likely occur across the globe as the U.S. and other biofuel feedstock-producing countries alter 

193 their agricultural sectors to allow for greater biofuel production. Many locations where biofuel 

194 production is growing are areas of high biodiversity value. For example, Indonesia (palm oil), 

195 Malaysia (palm oil), and Brazil (sugar ethanol) all contain ecosystems with well-above-average 

196 biodiversity. Depending where biofuel feedstock production occurs, impacts to biodiversity 

197 could be significant. Particularly in Malaysia and Indonesia, which have already lost 

198 considerable forest cover due to their large timber industries, expansion of palm oil plantations 

199 for biodiesel could potentially compound impacts on natural resources. However, because corn 

200 ethanol, the biofuel with the greatest potential for international impact in terms of trade pattern 

201 changes, is limited by the RFS2 and is likely to reach this limit in the next few years, these 

202 international impacts could level off as corn starch ethanol production levels off or is replaced by 

203 more advanced technologies. 
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204 As with domestic production, the choice of feedstock, how and where it is grown, the 

205 resulting land-use changes, and how it is produced and transported will have a large effect on 

206 how biofuel production and use affects water quality and availability, air quality (e.g. due to 

207 emissions from burning crop residue), and biodiversity. The specific impacts will reflect a 

208 country’s particular circumstances.

6.2

210 EISA Section 204 specifies that EPA include recommendations for actions to address any 

211 adverse impacts identified in this report. Responding specifically to this request requires a clear 

212 understanding of biofuel impacts and their causes. Impacts from corn starch and soybean 

213 production are relatively well understood, however, more information is needed about the 

214 adverse impacts associated with production of other feedstocks and with the production and use 

215 of advanced biofuel. This section presents four recommendations to address adverse impacts. 

216 Because biofuel impacts cross multiple topics and EPA responsibilities, EPA likely will address 

217 these recommendations through continued and strengthened cooperation with other federal 

218 agencies and international partners. 

209 Recommendations

219 6.2.1 Comprehensive Environmental Assessment

220 The biofuel industry is poised for significant expansion in the next few years. A variety 

221 of new technologies likely will be implemented and old technologies modified to meet the 

222 demands of affordable and sustainable petroleum fuel alternatives. As emphasized by Congress 

223 in requiring triennial biofuel impact assessments, it is important to evaluate the environmental 

224 implications associated with the ongoing growth of the dynamic biofuel industry. However, as 

225 noted earlier, the inherent complexity and uncertainty of environmental impacts across the 

226 biofuel supply chain make it difficult to provide assessments that are sufficiently definitive to 

227 inform environmental decisions. 

228 RECOMMENDATION: Develop and evaluate environmental life cycle assessments for 

229 biofuels. With this Report, EPA and the U.S. Departments of Agriculture and Energy (USDA 

230 and DOE) have begun to develop a framework and partnership that provide an important 

231 foundation for future assessments. Future assessments will address advanced biofuel production 

232 associated with specific feedstocks and associated by-products and provide a comparative 

233 context to fossil fuels. As described in Chapter 7, future assessments will be comprehensive and 

234 will address the major environmental parameters affected by increased biofuel production and 

235 use. These assessments will identify gaps and uncertainties in the knowledge base; inform the 

236 design and implementation of monitoring strategies and measures for evaluating impacts; 

237 provide comprehensive tools for comparing and evaluating development options; and provide the 

238 scientific bases for regulatory agencies and the biofuel industry to make environmentally 

239 conscious decisions. 

240 6.2.2 Coordinated Research

241 The biofuel industry is expected to expand rapidly and broadly. This expansion will be 

242 shaped to a large degree by the research behind the technological developments that make 
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243 biofuel production feasible. It will be important for the scientific infrastructure that supports 

244 policy and decision-making to keep pace with industry developments. 

245 RECOMMENDATION: Ensure the success of current and future environmental biofuel 

246 research through improved cooperation and sustained support. The Biomass Research and 

247 Development Board, co-chaired by DOE and USDA, currently monitors interagency biofuel 

248 research cooperation. The Board recently proposed that an inventory be conducted of federal 

249 activities and jurisdictions relevant to environmental, health, and safety issues associated with 

250 biofuel production in order to identify issues of concern, research needs, and mitigation options. 

251 Efforts to adjust and expand existing research programs to conduct biofuel-relevant research 

252 have been initiated. Prioritization and collaboration by the research community will be critical to 

253 provide meaningful results in the near term and to meet the wide variety of research needs, 

254 including many that have already been identified, that will be important to the industry and to 

255 appropriate regulatory oversight. 

256 6.2.3 Mitigation of Impacts from Feedstock Production 

257 As the biofuel industry expands, it will be important to optimize benefits while 

258 minimizing adverse impacts. Since many of the known adverse impacts are due to feedstock 

259 production, this Report has described the potential for mitigation of those impacts through the 

260 adoption of conservation systems and practices on farms. USDA has a variety of programs that 

261 help agriculture producers implement these conservation systems. As USDA’s Conservation 

262 Effects Assessment Project (CEAP) report on the Upper Mississippi River Basin demonstrates, 

263 much more needs to be done to control pollution from agriculture, especially from nitrogen. A 

264 collaborative effort is needed to develop and foster application of consistent and effective 

265 monitoring and mitigation procedures to protect the environment and conserve biodiversity and 

266 natural resources as biofuel production expands and advanced biofuels are commercially 

267 produced. 

268 RECOMMENDATION: Improve the ability of federal agencies (within their existing 

269 authorities) and industry to develop and implement best management and conservation 

270 practices and policies that will avoid or mitigate negative environmental effects from 

271 biofuel production and use. These policies and practices should be aligned and assessed within 

272 the context of the environmental life cycle assessment and take a multi-factor and multi-scale 

273 view of biofuels and their potential environmental effects. Priority areas for development include 

274 (1) improved containment processes that minimize environmental exposure from air emissions 

275 and runoff into surface and ground water, and (2) methods to monitor, track, and report biofuel 

276 environmental impacts. 

277 6.2.4 International Cooperation to Implement Sustainable Biofuel Practices 

278 EISA specifically identifies “significant emissions from land use change” as a potential 

279 environmental impact stemming from domestic biofuel production and consumption. This 

280 concern is relevant to all countries engaged in biofuel production, but as the U.S. increases 

281 domestic production of corn starch ethanol and soybean diesel, exports of corn and soybean for 

282 agricultural or other uses are expected to decline, which may result in indirect land use change in 

283 the form of land conversion to agriculture in other countries. Additional biofuel produced to 
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284 meet the EISA mandates will potentially lead to increases in acreages of international cropland, 

285 although these increases may level off after 2015 (see Section 5.2). 

286 RECOMMENDATION: Engage the international community in cooperative efforts to 

287 identify and implement sustainable biofuel practices that minimize environmental impact. 

288 U.S. and international capacity to minimize the consequences of land use change will depend not 

289 only the willingness of governments and industry to make environmentally sound choices 

290 regarding biofuel production, processing, and use, but also on the availability of cost-effective 

291 mitigation strategies. The U.S. can significantly contribute to such an effort by actively engaging 

292 the scientific community and biofuel industry to collaboratively develop the body of knowledge 

293 needed to support sound environmental decision-making. This effort will be facilitated by a 

294 greater understanding and appreciation of how increased biofuel demand may impact the 

295 environment internationally, particularly in countries that are most active, or most likely to 

296 become active in biofuel production. 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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1 7. ASSESSING ENVIRONMENTAL IMPACTS FROM BIOFUELS: 2013 TO 2022 

7.1

3 In requiring EPA to report triennially under EISA Section 204, Congress recognized that 

4 the environmental and resource conservation impacts of increased biofuel production and use 

5 will be dynamic, changing in both nature and scope, based on the amount, type, and location of 

6 biofuels produced and used. This first triennial Report to Congress, which reflects the state of 

7 scientific knowledge as of July 2010, is a first step toward identifying information that supports 

8 future assessment of environmental impacts from increased biofuel production and use. 

2 Introduction

9 This chapter outlines an approach EPA will use for its future assessments, beginning with 

10 the 2013 Report to Congress. In developing future assessments, EPA will work closely with the 

11 U.S. Departments of Agriculture and Energy (USDA and DOE) and will seek extensive input 

12 from industry and other stakeholders and peer review from the scientific community to create 

13 substantive, science-based analyses that facilitate environmental decision-making. Future 

14 assessments will benefit from advances in the science of environmental assessment and increased 

15 availability of relevant research results on this important topic. 

16 EPA anticipates that additional research and analyses will allow for more robust and 

17 quantitative assessments of biofuel environmental impacts than are reported here. For example, 

18 life cycle assessment (LCA) tools and approaches that are currently used for evaluating “cradle19 to-grave” resource consumption and waste disposal for specific products can be integrated into 

20 risk assessment to form a powerful composite approach for assessing environmental impacts. An

21 approach to more comprehensive environmental analyses that is consistent with the integration 

22 of LCA and risk assessment methods has been used in different assessments (Davis and Thomas, 

23 2006; Davis 2007). This approach would necessitate extending consideration of factors across 

24 the entire biofuel life cycle, including current and future feedstock production and biofuel 

25 conversion, distribution, use. The Agency has already applied LCA to assess greenhouse gas 

26 (GHG) emissions as part of its revised Renewable Fuel Standard (RFS2) program (U.S. EPA, 

27 2010b) and could adapt this approach to analyze other aspects of biofuel production and use, 

28 such as water consumption; evaluation of fossil fuels versus biofuels; net energy balance; 

29 production and use scenarios; and market impacts (economics). 

7.2

31 This section briefly describes key components that EPA plans to utilize in conducting its 

32 2013 assessment. Comprehensive environmental assessment (CEA) would provide an organizing 

33 framework for evaluating and, where possible quantifying, risk and benefits of biofuel 

34 production and use. CEA would integrate LCA, described in Section 7.2.1, and environmental 

35 risk assessment, described in Section 7.2.2. The latter could be used to systematically assess 

36 environmental risks, both human health (see Section 7.2.3) and ecological, for each stage in the 

37 life cycle and potentially cumulative impacts. Conceptual models (Section 7.2.4) will illustrate 

38 the important factors being considered in each stage of the life cycle and indicate how these 

39 factors are interrelated. Where possible, environmental indicators and other metrics (Section 

40 7.2.5) will be developed over the next several years to track the impacts of biofuel production 

41 and use throughout its life cycle and measure the effectiveness of regulatory and voluntary 

30 Components of the 2013 Assessment
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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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 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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82 understand the unique characteristics of the new fuel blends; how and when releases occur; the 

83 fate and transport of these releases; the relevant routes and duration of exposures to humans; and 

84 the toxic effects of those exposures. Both individual and population exposures will be important 

85 to consider. For example, populations in regions that both produce and use biofuel will 

86 experience different exposures than those in regions that only use the fuel. Individuals within the 

87 same region may experience different exposures (i.e., occupational, consumer, or public 

88 exposures), and vulnerable populations may be at greater risk of adverse effects, depending on 

89 their sensitivity. 

90 7.2.4 Conceptual Models 

91 A number of tools are available for use in problem formulation, including conceptual 

92 diagrams, which hypothesize relationships between activities and impacts. These diagrams can 

93 support multiple purposes, including defining system boundaries; enhancing understanding of 

94 the system being analyzed; and supporting communication among assessors, between assessors 

95 and stakeholders, and, ultimately, with risk managers. 

96 The information provided in Chapters 3, 4, and 5 of this 2010 assessment lay a 

97 foundation for constructing initial conceptual models to show relationships among biofuel 

98 activities and impacts. Figures 7-1 and 7-2 present generalized conceptual models for feedstock 

99 and biofuel production, respectively. Appendix D provides detailed conceptual diagrams for each 

100 of the feedstocks and fuels considered in this Report. Based on the information gathered during 

101 this 2010 assessment, the diagrams show the activities (e.g., crop rotation, water use) associated 

102 with the model’s domain area and how, through a series of relationships indicated with lines and 

103 arrows, these activities are associated with products and impacts. These diagrams are the first 

104 step in mathematically simulating the system and quantifying impacts. Diagrams such as these 

105 will be important tools for assessments in EPA’s future Reports to Congress. 

106 7.2.5 Monitoring, Measures, and Indicators 

107 EPA’s ability to accurately assess impacts attributable to biofuels production and use will 

108 depend on having timely, relevant, and accurate monitoring information that tracks potential 

109 impacts, and how effective regulatory and voluntary management practices, risk management 

110 practices, and other measures are in protecting the environment. While current environmental 

111 monitoring by various agencies can provide helpful information, targeted monitoring for 

112 potential biofuel impacts will be needed, requiring a collaborative effort across multiple agencies 

113 and other organizations. Indicators and measures will be important for a variety of environmental 

114 effects, including GHG emissions, human and ecological health indicators, eutrophication, and 

115 many others. These metrics will inform decisions at all levels along the biofuel supply chain and

116 well beyond the scope of the individual decision. 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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117 

118 Figure 7-1: Conceptual Diagram of the Environmental Impacts of Biofuel 

119 Feedstock Production
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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120 

121 Figure 7-2: Conceptual Diagram of the Environmental Impacts of Biofuel 

122 Production and Use
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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123 7.2.6 Scenarios

124 EPA’s 2013 Report to Congress will assess the environmental impacts of all five stages

125 in the biofuel supply chain (Figure 2-3). One approach may be to create scenarios based on 

126 volumetric biofuel requirements for 2022 as presented in the RFS2 (see Table 2-1). For example: 

127 • Scenario A: 2022 RFS2-projected feedstock mix produced with comprehensive 

128 conservation systems. 

 129 

130 • Scenario B: 2022 RFS2-projected feedstock mix produced with existing levels of 

131 conservation practice implementation. 

 132 

133 • Scenario C: 2022 conventional feedstock mix (corn starch, corn stover, and 

134 soybean) produced with existing levels of conservation practice implementation. 

 135 

136 Figure 7-3 shows possible impacts in all six impact categories for these three scenarios 

137 based on the feedstocks and fuels discussed in this Report. Scenarios are for illustrative purposes 

138 only to show the potential rage of environmental impacts given assumptions about feedstock 

139 production locations and practices; fuel production, transport, storage, and use patterns and 

140 technologies; and target volumes (Appendix C, Table C-3). They do not necessarily represent the 

141 most likely future developments in biofuel production systems. The magnitude, direction, and 

142 certainty of bars (see figure legend) are based on expert interpretation of all available scientific, 

143 peer-reviewed literature as of July 2010. Bars are relative to one another and do not reflect a 

144 comparison with petroleum-based transportation fuel. Future versions of this Report to Congress 

145 will expand and update this assessment. 

146 As noted earlier, the landscape of feedstock/biofuel production, conversion, and use is 

147 highly dynamic and constantly evolving. Which feedstocks and technologies are used and to 

148 what extent will be influenced by technological developments and market forces that are difficult 

149 to predict. Development of scenarios for future assessments will need to model or otherwise 

150 account for key factors that influence the biofuel market dynamics and associated environmental 

151 impacts. These factors include:

152 • Regional considerations. In general, biofuel conversion facilities will tend to be 

153 sited at reasonable distances from feedstock production areas, since cost 

154 considerations limit the distances over which biofuel feedstocks can be 

155 transported. Consequently, environmental impacts of both feedstock production 

156 and biofuel conversion will tend to be concentrated in particular regions. 

 157 

158 • Scale and volume of future commercial biofuel operations. Future development 

159 and application of commercially viable biofuel technologies will change the 

160 nature of energy feedstocks and conversion processes in use, as well as the scale 

161 of their operation. While the continued use of corn starch for ethanol will likely 

162 not change, the future profile of feedstocks and biofuels could vary from those 

163 used in 2010, but which will actually be used and to what extent is highly 

164 uncertain. 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

165 

166 

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

1 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. 

0.66 BG 0.66 BG 1.0 BG

0.1 BG 0.1 BG 0 BG

0.1 BG 0 BG

7.9 BG 7.9 BG 0 BG

15 BG 15 BG 15 BG

4.9 BG 4.9 BG 16 BG

0.1 BG

Sc. B: Envir. impacts 

from 2022 RFS2 

projected feedstock mix 

produced with minimal 

conservation/ BMPs and 

current technologies1

Corn 

Starch

Corn Stover Woody Biomass Perennial Grass Algae 

Sc. C: Envir. Impacts from 

2022 conventional 

feedstock mix produced 

with minimal 

conservation/ BMPs and 

current technologies1

Soybean 

Sc. A: Envir. impacts 

from 2022 RFS2 

projected feedstock mix 

produced with 

conservation/ BMPs and 

efficient technologies1

Conventional 

Ethanol Cellulosic Ethanol

Biomass-based 

Diesel

Legend

Magnitude Certainty 

(length of bar) Negative effect Negligible net effect Positive effect (shading)

Relatively large Least certain

Moderate Moderately certain

Relatively minor Most certain

Direction of Effect

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167 Figure 7-3: Cumulative Domestic Environmental Impacts of All Steps in the Biofuel Supply 

168 Chain System under Three Scenarios in 2022 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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169 • Hybrid processes. Biofuel conversion processes (e.g., biochemical and 

170 thermochemical processes) may evolve in the future to be hybrid processes that 

171 would produce not only biofuel but also synthetic chemicals and other industrial 

172 co-products. Integrated biorefineries may have the ability to make use of a 

173 biofuel-only or a hybrid conversion platform. Each new conversion option will 

174 present its own range of potential environmental impacts.

 175 

176 • Changes in vehicle technologies. Changes in vehicle technologies, patterns of 

177 vehicle sales, and fueling behavior will be needed to accommodate higher ethanol 

178 production volumes. Conversely, changes in vehicle technologies driven by other 

179 considerations, such as the development of plug-in hybrid electric or all-electric 

180 vehicles, could change the demand for liquid biofuels. 

 181 

182 • Changes in agricultural practices due to biofuel production and implications for

183 environmental impacts. Recent increases in ethanol production have expanded the 

184 market demand for corn grain, and farmers have responded to this increased 

185 demand by changing production practices from corn-soy rotations to corn-corn186 soy or even continuous corn production. It is not clear what the effects of 

187 production shifts, agricultural residue use, and associated farm-level management 

188 practice changes will be in the short term. 

 189 

190 7.2.7 Other Components 

191 In addition to the above components, the 2013 assessment will include a several analyses 

192 that provide important perspective for understand and evaluating the impacts of biofuel 

193 production and use, as described below. 

194 Comparison of Fossil Fuel to Biofuel. While this report provides a starting point for 

195 comparing the relative impacts associated with a range of different biofuel feedstock and 

196 production processes, it will also be useful to assess biofuel impacts in the larger context of the 

197 conventional petroleum fuels that are being displaced under the RFS2 mandates. Ideally, this 

198 comparison would cover the full life cycle for each fuel. Such an evaluation will facilitate 

199 comprehensive assessment of the relative costs and benefits of RFS2 beyond GHG impacts, and 

200 support identification of effective mitigation measures for key impacts. This type of evaluation 

201 has been recommended by the National Advisory Council for Environmental Policy and 

202 Technology as a means of conducting integrated environmental decision making (NACEPT 

203 2008). Given the limitations of currently available information, a comparative assessment of 

204 petroleum fuel and biofuel impacts will be largely qualitative, with significant data gaps and 

205 uncertainties. Nevertheless, EPA anticipates that even a qualitative comparative analysis will be 

206 an important component of the 2013 assessment. 

207 Net Energy Balance. Net energy balance (i.e., the amount of energy used to develop 

208 biofuels compared to the energy value derived from biofuels) is an important metric that will be 

209 addressed in the 2013 assessment. It enables comparison of biofuel produced from different 

210 feedstocks and via different conversion processes, as well as comparison between biofuel and 

211 gasoline. The net energy balance will include consideration of energy embedded in co-products 

212 of the fuel conversion process. For example, increases in corn ethanol production will increase 
Chapter 7: Assessing Environmental Impacts from Biofuels: 2013 to 2022

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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.
Chapter 8: References

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Chapter 8: References

This document is a draft for review purposes only and does not constitute Agency policy. 

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952 U.S. EPA (United States Environmental Protection Agency). 2002. A comprehensive analysis of 

953 biodiesel impacts on exhaust emissions. EPA-420-P-02-001. Available at: 

954 http://www.epa.gov/otaq/models/analysis/biodsl/p02001.pdf. 

955 U.S. EPA (United States Environmental Protection Agency). 2006a. Framework for developing 

956 suspended and bedded sediments (SABS) water quality criteria. EPA-822-R-06-001. 

957 Available at: http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=164423. 

958 U.S. EPA (United States Environmental Protection Agency). 2006b. Air quality criteria for 

959 ozone and related photochemical oxidants (2006 final). EPA-600-R-05-004aF-cF.

960 U.S. EPA (United States Environmental Protection Agency). 2006c. Wadeable Streams 

961 Assessment: A collaborative survey of the nation’s streams. EPA-841-B-06-002. 

962 Available at: http://www.epa.gov/owow/streamsurvey. 

963 U.S. EPA (United States Environmental Protection Agency). 2007a. Environmental law 

964 applicable to construction and operation of ethanol plants. EPA-907-B-07-001. Available 

965 at: http://www.epa.gov/region07/priorities/agriculture/pdf/ethanol_plants_manual.pdf. 

966 U.S. EPA (United States Environmental Protection Agency). 2008a. Environmental law 

967 applicable to construction and operation of biodiesel production facilities. EPA-907-B968 08-001. Available at: 

969 http://www.epa.gov/Region7/priorities/agriculture/pdf/biodiesel_manual.pdf. 

970 U.S. EPA (United States Environmental Protection Agency). 2008b. National coastal condition 

971 report—III. EPA-842-R-08-002. Available at: http://www.epa.gov/nccr. 

972 U.S. EPA (United States Environmental Protection Agency). 2008c. Applicability of effluent 

973 guidelines and categorical pretreatment standards to biodiesel manufacturing. Available 

974 at: http://www.epa.gov/npdes/pubs/memo_biodieselpretreatment_aug08.pdf. 

975 U.S. EPA (United States Environmental Protection Agency). 2009a. National water quality 

976 inventory: Report to Congress: 2004 reporting cycle. EPA-841-R-08-001. Available at: 

977 http://www.epa.gov/305b. 

978 U.S. EPA (United States Environmental Protection Agency). 2009b. Biofuels compendium. 

979 Available at: http://www.epa.gov/oust/altfuels/bfcompend.htm. 

980 U.S. EPA (United States Environmental Protection Agency). 2009c. Biofuels compendium—

981 ethanol—equipment compatibility. Available at: 

982 http://www.epa.gov/oust/altfuels/ethcompat.htm. 

983 U.S. EPA (United States Environmental Protection Agency). 2009d. Report to Congress on 

984 public health, air quality, and water resource impacts of fuel additive substitutes for 

985 MTBE, as required by Section 1505 of the Energy Policy Act 2005. 

986 U.S. EPA (United States Environmental Protection Agency). 2010a. Regulation of fuels and fuel 

987 additives: Changes to Renewable Fuel Standard Program: Final rule. Available at: 

988 http://www.regulations.gov/search/Regs/contentStreamer?objectId=0900006480ac93f2&

989 disposition=attachment&contentType=pdf. 

990 U.S. EPA (United States Environmental Protection Agency). 2010b. Renewable fuel standard 

991 program (RFS2) regulatory impact analysis. EPA-420-R-10-006. Available at: 

992 http://www.epa.gov/otaq/renewablefuels/420r10006.pdf. 

993 U.S. EPA (United States Environmental Protection Agency). 2010c. Water quality assessment 

994 and total maximum daily loads information (ATTAINS). Available at: 

995 http://www.epa.gov/waters/ir/index.html. 
Chapter 8: References

This document is a draft for review purposes only and does not constitute Agency policy. 

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996 U.S. EPA (United States Environmental Protection Agency). 2010d. National causes of 

997 impairment. In: National summary of state information. Available at: 

998 http://iaspub.epa.gov/waters10/attains_nation_cy.control#causes. 

999 U.S. EPA (United States Environmental Protection Agency). 2010e. Acetochlor (CASRN 34256-

1000 82-1). In: Integrated Risk Information System. Available at: 

1001 http://www.epa.gov/IRIS/subset/0521.htm. 

1002 U.S. EPA (United States Environmental Protection Agency). 2010f. Alachlor (CASRN 15972-

1003 60-8). In: Integrated Risk Information System. Available at: 

1004 http://www.epa.gov/IRIS/subst/0129.htm. 

1005 U.S. EPA (United States Environmental Protection Agency). 2010g. Carbaryl (CASRN 63-25-

1006 2). In: Integrated Risk Information System. Available at: 

1007 http://www.epa.gov/IRIS/subst/0019.htm. 

1008 U.S. EPA (United States Environmental Protection Agency). 2010h. Regulation of fuels and fuel 

1009 additives: Changes to renewable fuel standard program. EPA-HQ-OAR-2005-0161. 

1010 U.S. EPA (United States Environmental Protection Agency). 2010i. Definition of solid waste for 

1011 RCRA Subtitle C hazardous waste. Available at: http://www.epa.gov/osw/hazard/dsw/. 

1012 U.S. Forest Service. 2005. Evaluating sedimentation risks associated with fuel management. 

1013 RMRS-RN-23-8-WWW.

1014 U.S. Forest Service. 2010. Draft—National Report on Sustainable Forests—2010. Available at: 

1015 http://www.fs.fed.us/research/sustain/2010SustainabilityReport/documents/draft2010sust

1016 ainabilityreport.pdf. 

1017 U.S. ITC (United States International Trade Commission). 2010. Interactive Tariff and Trade 

1018 DataWeb. U.S. imports for consumption. Report: HTS-2207: Ethyl alcohol, undenatured 

1019 of an alcoholic strength by volume of 80% vol. or higher; ethyl alcohol and other spirits, 

1020 denatured, of any strength first unit of quantity by first unit of quantity. 

1021 Van der Steen, NP; Nakiboneka, P; Mangalika, L; Ferrer, AVM; Gijzen, HJ. 2003. Effect of 

1022 duckweed cover on greenhouse gas emissions and odor release from waste stabilization 

1023 ponds. Water Science and Technology 48(2): 341-348. 

1024 Vogel, KP; Masters, RA. 1998. Developing switchgrass into a biomass fuel crop for the 

1025 midwestern USA. Paper presented at BioEnergy ’98: Expanding Bioenergy Partnerships, 

1026 Madison, Wisconsin, 4–8 October 1998. 

1027 Volk, TA; Abrahamson, LP; Nowak, CA; Smart, LB; Tharakan, PJ; White, EH. 2006. The 

1028 development of short-rotation willow in the northeastern United States for bioenergy and 

1029 bioproducts, agroforestry and phytoremediation. Biomass and Bioenergy 30(8-9): 

1030 715-727. 

1031 Von Blottnitz, H; Curran, MA. 2007. A review of assessments conducted on bio-ethanol as a 

1032 transportation fuel from a net energy, greenhouse gas, and environmental life cycle 

1033 perspective. Journal of Cleaner Production 15: 607-619. 

1034 Walsh, ME; de la Torre Ugarte, DG; Shapouri, H; Slinsky, SP. 2003. Bioenergy crop production 

1035 in the United States: Potential quantities, land use changes, and economic impacts on the 

1036 agricultural sector. Environmental and Resource Economics 24(4): 313-333. 

1037 Walter, WD; Vercauteren, KC; Gilsdorf, JM; Hygnstrom, SE. 2009. Crop, native vegetation, and 

1038 biofuels: Response of white-tailed deer to changing management priorities. Journal of 

1039 Wildlife Management 73: 339-344. 
Chapter 8: References

This document is a draft for review purposes only and does not constitute Agency policy. 

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1040 Wang, L; Robertson, DM; Garrison, PJ. 2007a. Linkages between nutrients and assemblages of 

1041 macroinvertebrates and fish in wadeable streams. Environmental Management 39: 194-

1042 212. Available at : http://www.springerlink.com/content/4k441384336k1x28/fulltext.pdf. 

1043 Wang, M; Wu, M; Huo, H. 2007b. Life-cycle energy and greenhouse gas emission impacts of 

1044 different corn ethanol plant types. Environmental Research Letters 2: 1-13. 

1045 Weed, DAJ; and Kanwar, RS. 1996. Nitrate and water present in and flowing from root-zone 

1046 soil. Journal of Environmental Quality 25: 709-719. 

1047 Weibe, K; Gollehon, N. 2006. Agricultural resources and environmental indicators, 2006 edition. 

1048 Economic Information Bulletin No. (EIB-16). U.S. Department of Agriculture, Economic 

1049 Research Service. Available at: http://www.ers.usda.gov/publications/arei/eib16/. 

1050 Weigelt, A; Weisser, WW; Buchmann, N; Scherer-Lorenzen, M. 2009. Biodiversity for 

1051 multifunctional grasslands: Equal productivity in high-diversity low-input and low1052 diversity high-input systems. Biogeosciences 6: 1695-1706. 

1053 Whalen, J; Cissel, B. 2009. Soil insect management in field corn. University of Delaware 

1054 Cooperative Extension. 

1055 Whicker, JJ; Pinder, JE; Breshears, DD. 2008. Thinning semiarid forests amplifies wind erosion 

1056 comparably to wildfire: Implications for restoration and soil stability. Journal of Arid 

1057 Environments 72(4): 494-508. 

1058 White, EM. 2010. Woody biomass for bioenergy and biofuels in the United States—a briefing 

1059 paper. Gen. Tech. Rep. PNW-GTR-825. U.S. Department of Agriculture. 

1060 Wilkinson, M; Tepfer, M. 2009. Fitness and beyond: Preparing for the arrival of GM crops with 

1061 ecologically important novel characters. Environmental Biosafety Research 8: 1-14. 

1062 Williams, PR; Inman, DD; Aden, A; Heath, GA. 2009. Environmental and sustainability factors 

1063 associated with next-generation biofuels in the U.S.: What do we really know? 

1064 Environmental Science and Technology 43: 4763-4775. 

1065 Wiltsee, G. 1998. Urban waste grease resource assessment. NREL/SR-570-26141. National 

1066 Renewable Energy Laboratory. Available at: 

1067 http://www.biodiesel.org/resources/sustainability/pdfs/NREL%20Urban%20Waste%20G

1068 rease%20Resources%20Assessment.pdf. 

1069 Winebrake, J; Wang, M; He, D. 2001. Toxic emissions from mobile sources: A total fuel-cycle 

1070 analysis for conventional and alternative fuel vehicles. Journal of the Air and Waste 

1071 Management Association 51: 1073-1086. 

1072 Wolt, JD. 2009. Advancing environmental risk assessment for transgenic biofeedstock crops. 

1073 Biotechnology for Biofuels. 2: 27 doi: 10.1186/1754-6834-2-27. 

1074 Wösten, JHM; van den Berg, J; van Eijk, P; Gevers, GHM; Giesen, WBJT; Hooijer, A; Idris, A; 

1075 Leenman, PH; Rais, DS; Siderius, C; Silvius, MJ; Suryadiputra, N; Wibisono, IT. 2006. 

1076 Interrelationships between hydrology and ecology in fire degraded tropical peat swamp 

1077 forests. International Journal of Water Resources Development 22(1): 157-174. 

1078 Wright LL. 1994. Production technology status of woody and herbaceous crops. Biomass and 

1079 Bioenergy 6(3): 191-210. 

1080 Wu, M. 2008. Analysis of the efficiency of the U.S. ethanol industry. Center for Transportation 

1081 Research, Argonne National Laboratory.

1082 Wu, M; Wang, M. 2006. Energy and emission benefits of alternative transportation liquid fuel 

1083 derived from switchgrass: A fuel life-cycle assessment. Biotechnology Progress 22(4): 

1084 1012-1024. 
Chapter 8: References

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1085 Wu, M; Mintz, M; Wang, M; Arora, S. 2009. Water consumption in the production of ethanol 

1086 and petroleum gasoline. Environmental Management 44: 981-997. 

1087 Yacobucci, B. 2005. CRS report to Congress: Ethanol imports and the Caribbean Basin 

1088 Initiative. Congressional Research Service. Order Code RS21930. Available at: 

1089 http://www.policyarchive.org/handle/10207/bitstreams/3978.pdf. 

1090 Yanowitz, J; McCormick, R. 2009. Effect of E85 on tailpipe emissions from light-duty vehicles. 

1091 Journal of the Air and Waste Management Association 59: 172–182. 

1092 Zah, R; Ruddy, TF. 2009. International trade in biofuels: An introduction to the special issue. 

1093 Journal of Cleaner Production 17: S1-S3. 

1094 Zavaleta, ES; Pasari, JR; Hulvey, KB; Tilman, GD. 2010. Sustaining multiple ecosystem 

1095 functions in grassland communities requires higher biodiversity. Proceedings of the 

1096 National Academy of Sciences of the United States of America 107: 1443-1446. 

1097 Zhu, Y; Fox, RH. 2003. Corn-soybean rotation effects on nitrate leaching. Agronomy 

1098 Journal 95: 1028-1033. 

1099 
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1 Appendix A

2 

3 Glossary and Acronyms
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4 advanced biofuel: A renewable fuel, other than ethanol derived from corn starch that has life 

5 cycle greenhouse gas (GHG) emissions that are at least 50 percent less than life cycle GHG 

6 emissions from petroleum fuel. A 60-percent reduction in GHG is required from cellulosic 

7 biofuels to get credit for being an “advanced” biofuel. 

 8 

9 agricultural residue: Plant parts, primarily stalks and leaves that are not removed from fields 

10 used for agriculture during harvesting of the primary food or fiber product. Examples include 

11 corn stover (stalks, leaves, husks, and cobs), wheat straw, and rice straw. 

 12 

13 algae: Any plant-like organisms that are usually photosynthetic and aquatic, but do not have true 

14 roots, stems, leaves, or vascular tissue, and that have simple reproductive structures. Algae are 

15 distributed worldwide in the sea, in fresh water, and in wastewater. Most are microscopic, but 

16 some are quite large (e.g., some marine seaweeds that can exceed 50 meters in length). 

17 B100: Pure (i.e., 100 percent) biodiesel, also known as “neat biodiesel.” 

 18 

19 B20: A fuel mixture that includes 20 percent biodiesel and 80 percent conventional diesel and 

20 other additives. Similar mixtures, such as B5 or B10, also exist and contain 5 and 10 percent 

21 biodiesel, respectively.

 22 

23 Best Management Practices (BMPs): Best management practices are the techniques, methods, 

24 processes, and activities commonly accepted and used to facilitate compliance with applicable

25 requirements, and that provide an effective and practicable means of avoiding or reducing the 

26 potential environmental impacts. 

 27 

28 biodiesel (also known as “biomass-based diesel”): A renewable fuel produced through 

29 transesterification of organically derived oils and fats. May be used as a replacement for or 

30 component of diesel fuel. 

 31 

32 biodiversity: The variety and variability among living organisms and the ecological complexes 

33 in which they occur. Biodiversity can be defined as the number and relative frequency of 

34 different items, from complete ecosystems to the biochemical structures that are the molecular

35 basis of heredity. Thus, the term encompasses ecosystems, species, and genes.

 36 

37 biofuel: Any fuel made from organic materials or their processing and conversion derivatives. 

 38 

39 biofuel blend: Fuel mixtures that include a blend of renewable biofuel and petroleum-based fuel. 

40 This is opposed to “neat form” biofuel that is pure, 100 percent renewable biofuel. 

 41 

42 biofuel distribution: Transportation of biofuel to blending terminals and retail outlets by a 

43 variety of means, including rail, barge, tankers, and trucks. This almost always includes periods 

44 of storage.

 45 

46 biofuel end use: Combustion of biofuel in vehicles and various types of engines, usually as a 

47 blend with gasoline or diesel, or in some cases in neat form.

 48 
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49 biofuel life cycle: All the consecutive and interlinked stages of biofuel production and use, from 

50 feedstock generation to biofuel production, distribution, and end use by the consumer. 

 51 

52 biofuel production: The process or processes involved in converting a feedstock into a 

53 consumer-ready biofuel. 

 54 

55 biofuel supply chain: The five main stages involved in the life cycle of a biofuel: feedstock 

56 production, feedstock logistics, fuel production, fuel distribution, and fuel use. 

 57 

58 biogenic: Produced by living organisms or a biological process.

 59 

60 biomass: Any plant-derived organic matter (e.g., agricultural crops and crop wastes; wood and 

61 wood wastes and residues; aquatic plants; perennial grasses).

 62 

63 biomass-based diesel: See “biodiesel” above. Biomass-based diesel includes non-co-processed 

64 renewable diesel, which does not use the transesterification technology. 

 65 

66 cellulosic biofuel: A renewable fuel derived from lignocellulose (i.e., plant biomass comprised 

67 of cellulose, hemicellulose, and lignin that is a main component of nearly every plant, tree, and 

68 bush in meadows, forests, and fields). Lignocellulose is converted to cellulosic biofuel by 

69 separating the sugars from the residual material, mostly lignin, and then fermenting, distilling, 

70 and dehydrating this sugar solution. 

 71 

72 Conservation Reserve Program (CRP): A U.S. Department of Agriculture program that 

73 provides technical and financial assistance to eligible farmers and ranchers to address soil, water, 

74 and related natural resource concerns on their lands in an environmentally beneficial and cost75 effective manner. It encourages farmers to convert highly erodible cropland or other 

76 environmentally sensitive acreage to vegetative cover, such as tame or native grasses, wildlife 

77 plantings, trees, filter strips, or riparian buffers. Farmers receive an annual rental payment for the 

78 term of the multi-year contract. 

 79 

80 conservation tillage: Any cultivation system that leaves at least one third of the land surface 

81 covered with residue after planting in order to reduce soil erosion and conserve soil productivity. 

82 One example would be “no-till,” where fields are not tilled at all and crops are planted directly 

83 into the existing residue. Other variations include “strip-till” or “ridge-till,” which remove some, 

84 but not all, of the residue from the harvested area.

 85 

86 conventional biofuel: In the context of this report, “conventional biofuel” refers to ethanol 

87 derived from corn starch that does not lead to at least a 50 percent reduction in greenhouse gas 

88 emissions compared to petroleum.

 89 

90 corn stover: The stalks, leaves, husks, and cobs that are not removed from the fields when the 

91 corn is harvested. 

 92 

93 crop yield: The quantity of grains or dry matter produced from a particular area of land. (In this 

94 report, crop yield is most often measured in corn or soybean bushels per acre.) 
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95 direct land use change: In the context of biofuel, “direct land use change” refers to land 

96 conversion that is directly related and easily attributable to the biofuel supply chain. For 

97 example, a U.S. farmer deciding to take land out of the Conservation Reserve Program in order 

98 to grow more corn for ethanol would be considered a direct land use change. 

99 double cropping: The process of planting two different crops (not including cover crops) on the 

100 same piece of land over the course of a growing season.

101 dry milling: A process for producing conventional corn starch ethanol in which the kernels are 

102 ground into a fine powder and processed without fractionating the grain into its component parts. 

103 Most ethanol comes from dry milling.

 104 

105 E10: A fuel mixture of 10 percent ethanol and 90 percent gasoline based on volume. 

 106 

107 E85: A fuel mixture of 85 percent ethanol and 15 percent gasoline based on volume. 

 108 

109 ecosystem health: The ability of an ecosystem to maintain its metabolic activity level and 

110 internal structure and organization, and to resist external stress over time and space scales 

111 relevant to the ecosystem.

 112 

113 effluent: Liquid or gas discharged in the course of industrial processing activities, usually 

114 containing residues from those processes. 

 115 

116 Energy Independence and Security Act (Public Law 110-140) (EISA): Signed into law on 

117 December 19, 2007, this legislation established energy management goals and requirements 

118 while also amending portions of the National Energy Conservation Policy Act. EISA’s stated 

119 goals are to move the U.S. toward greater energy independence and security; increase production 

120 of clean renewable fuels; protect consumers; increase the efficiency of products, buildings, and 

121 vehicles; promote research on and deploy greenhouse gas capture and storage options; and 

122 improve the energy performance of the federal government.

 123 

124 environmental life cycle assessment: In the context of this report, an environmental life cycle 

125 assessment is an assessment in which the LCA methodology (see “life cycle assessment”) is 

126 applied to address the full range of potential environmental impacts over all environmental 

127 media. 

 128 

129 ethanol (also known as “bioethanol”): A colorless, flammable liquid produced by fermentation 

130 of sugars. Ethanol is used directly as a fuel and fuel oxygenate.

 131 

132 eutrophication: Nutrient enrichment of aquatic ecosystems, in which excessive nutrient levels 

133 cause accelerated algal growth, which in turn can reduce light penetration and oxygen levels in 

134 water necessary for healthy aquatic ecosystems. Eutrophication can cause serious deterioration of 

135 both coastal and inland water resources and can lead to hypoxia. 

 136 

137 feedstock: In the context of biofuel, “feedstock” refers to a biomass-based material that is 

138 converted for use as a fuel or energy product. 

 139 
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140 feedstock logistics: All activities associated with handling, storing, and transporting feedstocks 

141 after harvest to the point where the feedstocks are converted to biofuel. 

 142 

143 feedstock production: All activities associated with cultivation and harvest of biofuel feedstock. 

 144 

145 filter strip: A strip or area of herbaceous vegetation that may reduce nutrient loading, soil 

146 erosion, and pesticide contamination by removing soil particles and contaminants from overland 

147 water flow.

148 forest residue: Includes 1) tops, limbs, and other woody material not removed in forest 

149 harvesting operations in commercial hardwood and softwood stands; and 2) woody material 

150 resulting from forest management operations such as pre-commercial thinning and removal of 

151 dead and dying trees.

 152 

153 forest thinning: Removal of residues from overgrown forests to reduce forest fire risk or 

154 increase forest productivity. Residues are typically too small or damaged to be sold as round 

155 wood but can be used as biofuel feedstock. 

 156 

157 greenhouse gases: Gases that trap the heat of the sun in the Earth's atmosphere, producing the 

158 greenhouse effect. Greenhouse gases include water vapor, carbon dioxide, hydrofluorocarbons, 

159 methane, nitrous oxide, perfluorocarbons, and sulfur hexafluoride. 

 160 

161 harvesting forest residue: See “forest thinning” above. 

 162 

163 hemicellulose: any of various plant polysaccharides less complex than cellulose and easily 

164 hydrolysable to monosaccharides (simple sugars) and other products. 

 165 

166 hybrid: A plant species created from the offspring of genetically different parents, both within 

167 and between species. Hybrids combine the characteristics of the parents or exhibit new ones. 

 168 

169 hypoxia: The state of an aquatic ecosystem characterized by low dissolved oxygen levels (less 

170 than 2 to 3 parts per million) due to accelerated algal growth and reduced light penetration 

171 because of excessive nutrient levels (eutrophication). Low dissolved oxygen can reduce fish 

172 populations and species diversity in the affected area.

 173 

174 indirect land use change: In the context of biofuel, “indirect land use change” refers to land 

175 conversion that occurs as a market response to changes in the supply and demand of goods other 

176 than biofuel (e.g., food commodities) that result from changes in biofuel demand. For example, 

177 clearing of foreign land to plant corn as a food crop in response to reduced U.S. corn exports 

178 caused by increased use of U.S. corn to produce ethanol is considered to be an indirect land use 

179 change. 

180 

181 integrated pest management (IPM): An environmentally sensitive approach to pest 

182 management that uses current, comprehensive information on the life cycles of pests and their 

183 interaction with the environment to manage pest damage by the most economical means, and 

184 with the least possible hazard to people, property, and the environment. 

 185 
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186 invasive plants (also called invasives or noxious plants): An alien species whose introduction 

187 does or is likely to cause economic or environmental harm or harm to human health. 

 188 

189 land cover: Vegetation, habitat, or other material covering a land surface.

 190 

191 land use: The human use of land involving the management and modification of natural 

192 environment or wilderness into built environment such as fields, pastures, and settlements. 

 193 

194 life cycle assessment: A comprehensive systems approach for measuring the inputs, outputs, and 

195 potential environmental impacts of a product or service over its life cycle, including resource 

196 extraction/generation, manufacturing/production, use, and end-of-life management.

 197 

198 life cycle greenhouse gas emissions: The aggregate quantity of greenhouse gas emissions 

199 (including direct emissions and significant indirect emissions such as significant emissions from 

200 land use changes), as determined by the EPA Administrator, related to the full fuel life cycle, 

201 where the mass values for all greenhouse gases are adjusted to account for their relative global 

202 warming potential. (See above for definition of “biofuel life cycle.”) 

 203 

204 low-till: See “conservation tillage.”

 205 

206 milling residues (primary and secondary): Wood and bark residues produced in processing (or

207 milling) logs into lumber, plywood, and paper. 

 208 

209 mitigation: In the context of the environment, action to reduce adverse environmental impacts. 

 210 

211 neat biofuel: See “B100.” 

 212 

213 net energy balance: In the context of biofuel, refers to the energy content in the resulting 

214 biofuel less the total amount of energy used over the production and distribution process. 

 215 

216 nitrogen fixation: The transformation of atmospheric nitrogen into nitrogen compounds that can 

217 be used by growing plants. Nitrogen-fixing species, such as soybeans, can accomplish this 

218 process directly.

 219 

220 nutrient loading: A process in which compounds from waste and fertilizers, such as nitrogen 

221 and phosphorus, enter a body of water. This can happen, for example, when sewage is managed 

222 poorly, when animal waste enters ground water, or when fertilizers from residential and 

223 agricultural runoff wash into a stream, river, or lake. 

 224 

225 oxygenated fuels: Fuels, typically gasoline, that have been blended with alcohols or ethers that 

226 contain oxygen in order to reduce carbon monoxide and other emissions. 

 227 

228 ozone: A form of oxygen consisting of three oxygen atoms. In the stratosphere (7 to 10 miles or 

229 more above the Earth's surface), ozone is a natural form of oxygen that shields the Earth from 

230 ultraviolet radiation. In the troposphere (the layer extending up 7 to 10 miles from the Earth's 

231 surface), ozone is a widespread pollutant and major component of photochemical smog. 
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 232 

233 perennial grass: A species of grass that lives more than two years and typically has low nutrient 

234 demand and diverse geographical growing range, and offers important soil and water 

235 conservation benefits. 

 236 

237 photobioreactor: A vessel or closed-cycle recirculation system containing some sort of 

238 biological process that incorporates some type of light source. Often used to grow small 

239 phototrophic organisms such as cyanobacteria, moss plants, or algae for biodiesel production. 

 240 

241 renewable biomass: As defined by the 2007 Energy Independence and Security Act, renewable 

242 biomass means each of the following: 

 243 

244 • Planted crops and crop residue from agricultural land cleared prior to December 

245 19, 2007, and actively managed or fallow on that date.

246 • Planted trees and tree residue from tree plantations cleared prior to December 19, 

247 2007, and actively managed on that date. 

248 • Animal waste material and byproducts.

249 • Slash and pre-commercial thinnings from non-federal forestlands that are neither 

250 old-growth nor listed as critically imperiled or rare by a State Natural Heritage 

251 program. 

252 • Biomass cleared from the vicinity of buildings and other areas at risk of wildfire.

253 • Algae.

254 • Separated yard waste and food waste.

 255 

256 renewable fuel: A fuel produced from renewable biomass that is used to replace or reduce the 

257 use of fossil fuel. 

 258 

259 Renewable Fuels Standard (RFS) program: An EPA program created under the Energy Policy 

260 Act (EPAct) of 2005 that established the first renewable fuel volume mandate in the United 

261 States. The original RFS program (RFS1) required 7.5 billion gallons of renewable fuel to be 

262 blended into gasoline by 2012. (See below for RFS2.) 

 263 

264 RFS2: The Renewable Fuels Standard program as revised in response to requirements of the 

265 2007 Energy Independence and Security Act. RFS2 increased the volume of renewable fuel 

266 required to be blended into transportation fuel to 36 billion gallons per year by 2022. 

 267 

268 RFS2 Regulatory Impact Analysis (RIA): EPA’s analysis of the impacts of the increase in 

269 production, distribution, and use of the renewable fuels need to meet the RFS2 volumes 

270 established by Congress in the 2007 Energy Independence and Security Act (EISA). 

 271 

272 riparian forest buffer: An area of trees and shrubs located adjacent to streams, lakes, ponds, 

273 and wetlands that may reduce nutrient loading, soil erosion, and pesticide contamination by 

274 removing soil particles and contaminants from overland water flow. 

275 row crop: A crop planted in rows wide enough to allow cultivators between the rows. Examples 

276 include corn, soybeans, peanuts, potatoes, sorghum, sugar beets, sunflowers, tobacco, vegetables, 

277 and cotton. 
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 278 

279 sedimentation: The process of solids settling out of water due to gravity.

 280 

281 short rotation woody crop (SRWC): Fast-growing tree species grown on plantations and 

282 harvested in cycles shorter than is typical of conventional wood products, generally between 3 to 

283 15 years. Examples include: hybrid poplars (Populus spp.), willow (Salix spp.), Loblolly pine 

284 (Pinus taeda), and Eucalyptus. 

 285 

286 soil erosion: The wearing away of land by the action of wind, water, gravity, or a combination 

287 thereof.

 288 

289 soil organic matter: Decomposing plant and animal material in soil. 

 290 

291 soil quality: The capacity of a specific kind of soil to function, within natural or managed 

292 ecosystem boundaries, to sustain plant and animal productivity, maintain or enhance water and 

293 air quality, and support human health and habitation. 

 294 

295 sugarcane bagasse: The fibrous material that remains after sugar is pressed from sugarcane. 

 296 

297 sweet sorghum pulp: The bagasse or dry refuse left after the juice is extracted from sweet 

298 sorghum stalks during the production of ethanol and other sweet sorghum products. The pulp is 

299 usually treated as farm waste in plantations that grow sweet sorghum for biofuel production. 

 300 

301 transesterification: In the context of biofuel, the chemical process that reacts an alcohol with 

302 triglycerides in vegetable oils and animal fats to produce biodiesel and glycerin. 

 303 

304 turbidity: A cloudy condition in water due to suspended silt or organic matter.

 305 

306 vegetative reproduction: A form of asexual reproduction in plants by which new individuals 

307 arise without the production of seeds or spores. It can occur naturally or be induced by 

308 horticulturists. 

 309 

310 water availability: In the context of this report, water availability refers to the amount of water 

311 that can be appropriated from surface water sources (e.g., rivers, streams, lakes) or ground water 

312 sources (e.g., aquifers) for consumptive uses. 

 313 

314 water quality: Water quality is a measure of the suitability of water for a particular use based on 

315 selected physical, chemical, and biological characteristics. It is most frequently measured by 

316 characteristics of the water such as temperature, dissolved oxygen, and pollutant levels, which 

317 are compared to numeric standards and guidelines to determine if the water is suitable for a 

318 particular use

 319 

320 wet milling: In the context of biofuel, a process for producing conventional corn starch ethanol 

321 in which the corn is soaked in water or dilute acid to separate the grain into its component parts 

322 (e.g., starch, protein, germ, oil, kernel fibers) before converting the starch to sugars that are then 

323 fermented to ethanol. 
Appendix A

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 A-9 DRAFT—DO NOT CITE OR QUOTE

 324 

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 
Appendix B

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 B-1 DRAFT—DO NOT CITE OR QUOTE

1 APPENDIX B: 

2 

3 SUMMARY OF SELECTED STATUTORY AUTHORITIES 

4 HAVING POTENTIAL IMPACT ON THE PRODUCTION 

5 AND USE OF BIOFUELS
Appendix B

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 B-2 DRAFT—DO NOT CITE OR QUOTE

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Clean Air Act (CAA) (http://www.epa.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. 
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Clean Water Act (CWA) (http://www.epa.gov/watertrain/cwa/)

The goal of the CWA is to restore 

and maintain the chemical, 

physical, and biological integrity of 

the nation’s waters. 

Entities that discharge to waters of 

the 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.” 
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

CWA: Section 404 Wetlands Program (www.epa.gov/owow/wetlands/laws/)

Section 404 addresses the 

discharges of dredged or fill 

material into waters of the United 

States, including wetlands. 

Permits are required for activities 

such as expanded water resource 

projects (including dams, 

impoundments, and levees) and 

altering or dredging a water of the 

United States.

Most ongoing agricultural 

maintenance practices are 

exempt from Section 404. 

Generally, Section 404 requires a permit before these 

materials may be placed in a U.S. water, such as a 

wetland, stream, river, slough, lake, bay, etc., during 

construction activities.

Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) (http://www.epa.gov/lawsregs/laws/cercla.html)

CERCLA provides a federal 

"Superfund" to clean up 

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. 
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Emergency Planning and Community Right Know ACT (EPCRA) (http://www.epa.gov/oecaagct/lcra.html)

The objective of the EPCRA is to: 

(1) allow state and local planning 

for chemical emergencies, (2) 

provide for notification of 

emergency releases of chemicals, 

and (3) address communities' rightto-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. 
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) (http://www.epa.gov/oecaagct/lfra.html)

The objective of FIFRA is to 

provide federal control of pesticide 

distribution, sale, and use.

EPA reviews and 

registers pesticides for 

specified uses and can 

cancel the registration if 

information shows 

continued use would pose 

unreasonable risk. 

Consideration is given to 

worker exposure 

ecological exposure and 

food-chain imports.

Hazardous Materials Transportation Act (Regulations codified 49 CFR) (http://www.phmsa.dot.gov/hazmat/regs and

http://www.fmcsa.dot.gov/safety-security/hazmat/security-plan-guide.htm)

The Department of Transportation 

regulations require procedures to be 

put in place ensuring the safe 

transport of hazardous materials. 

Also, regulation HM-232 requires 

companies to complete a written 

security assessment and to develop 

a security plan 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. 
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

National Environmental Policy Act (NEPA) (http://www.epa.gov/compliance/nepa/)

NEPA requires federal agencies to 

integrate environmental values into 

their decision making processes by 

considering the environmental 

impacts of their proposed actions 

and reasonable alternatives to those 

actions. To meet NEPA 

requirements in certain 

circumstances federal agencies 

prepare a detailed statement known 

as an Environmental Impact 

Statement (EIS).

If federal money is being used to partially or entirely 

finance the construction of a biofuel plant or any 

associated facility, such as an access road or water 

supply facility, then construction of the plant may be

subject to NEPA. NEPA requires federal agencies to 

incorporate environmental considerations in their 

planning and decision-making and to prepare a 

detailed statement assessing the environmental impact 

of activities and alternatives that significantly affect 

the environment.

Oil Pollution Act (OPA) of 1990 (http://www.epa.gov/lawsregs/laws/opa.html)

The OPA of 1990 streamlined and 

strengthened EPA’s ability to 

prevent and respond to catastrophic 

oil spills. A trust fund financed by a 

tax on oil is available to clean up 

spills when the responsible party is 

incapable or unwilling to do so. The 

OPA requires oil storage facilities 

and vessels to submit to the Federal 

government plans detailing how 

they will respond to large 

discharges. 

Provides that the responsible party for a vessel or 

facility from which oil is discharged, or which poses a 

substantial threat of a discharge, is liable for: (1) 

certain specified damages resulting from the 

discharged oil; and (2) removal costs incurred in a 

manner consistent with the National Contingency Plan. 

Provides for spill contingency plans and mandates 

development of response plans for worst case 

discharge; 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.
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Renewable Fuel Standard (RFS) (http://www.epa.gov/otaq/fuels/renewablefuels/index.htm)

The RFS program was created 

under the Energy Policy Act 

(EPAct) of 2005, and established 

the first renewable fuel volume 

mandate in the United States. As 

required under EPAct, the original 

RFS program (RFS1) required 7.5 

billion gallons of renewable fuel to 

be blended into gasoline by 2012.

Under the Energy Independence 

and Security Act (EISA) of 2007, 

the RFS program was expanded. 

EISA also required EPA to apply 

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
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Resource Conservation and Recovery Act (RCRA) (http://www.epa.gov/lawsregs/laws/rcra.html)

RCRA gives EPA the authority to 

control hazardous waste generation, 

transportation, treatment, storage, 

and disposal of hazardous waste. 

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.epa.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.
Appendix B

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

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Safe Drinking Water Act: Underground Injection Control (UIC) Program (http://www.epa.gov/safewater/uic/)

The UIC program protects 

underground sources of drinking 

water by regulating the 

construction, operation, permitting, 

and closure of injection wells that 

place fluids underground for storage 

or disposal.

Agriculture drainage 

wells are Class V UIC 

wells. They are primarily 

regulated under state law.

A biofuels plant is subject to the requirements of the 

UIC Program if any of the following apply: 

• It is disposing of 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 Countermeasure (SPCC) and Facility Response Plans (FRP) (http://www.epa.gov/oem/content/spcc/index.htm)

The SPCC rule includes 

requirements for oil spill 

prevention, preparedness, and 

response to prevent oil discharges 

to navigable waters and adjoining 

shorelines. The rule requires 

specific facilities to prepare, amend, 

and implement SPCC Plans. The 

SPCC rule is part of the Oil 

Pollution Prevention regulation, 

which also includes the 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.
Appendix B

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 B-11 DRAFT—DO NOT CITE OR QUOTE

Table B-1: 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 Biofuel Production, Transport, and Storage Use of Biofuel

Toxic Substances Control Act (TSCA) (http://www.epa.gov/lawsregs/laws/tsca.html)

TSCA gives EPA broad authority to 

identify and control chemical 

substances that may pose a threat to 

human health or the environment. 

EPA's Office of Pollution 

Prevention and Toxics operates 

both the New Chemicals Program 

and the Biotechnology Program 

under Section 5 of TSCA. Both 

programs were established to help 

manage the potential risk from 

chemical substances and 

genetically-engineered 

(intergeneric) microorganisms new 

to the marketplace or applied in 

significant new uses. Additional 

sections of TSCA give EPA the 

broad authority to issue toxicity 

testing orders or to regulate the use 

of any existing chemicals that pose 

unreasonable risk.

Notification and review 

of new intergeneric 

genetically engineered 

microbes (e.g. bacteria, 

fungi and algae) used to 

produce 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.
Appendix C

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 C-1 DRAFT—DO NOT CITE OR QUOTE

1 Appendix C

2 

3 Basis for Figures 6-1, 6-2, and 7-3 
Appendix C

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

4 This appendix presents three tables, Tables C-1, 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-1 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-1: 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 

high 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. 
Appendix C

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

Table C-1: 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

Soybean

Most current soybean 

biofuel production comes 

from increased allocation 

of existing harvest to 

biodiesel. 

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.

Water Quantity Irrigated soy replaces non-irrigated land 

use in drier area.

Non-irrigated soy replaces irrigated corn.

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.

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.
Appendix C

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

Table C-1: 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 Stover

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.

Water Quantity High rate of stover removal on irrigated 

land in drier areas.

Appropriate rate of stover removal to 

minimize additional irrigation given sitespecific 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.

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.
Appendix C

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

Table C-1: 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.
Appendix C

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 C-6 DRAFT—DO NOT CITE OR QUOTE

Table C-1: 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

Perennial Grass

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 nonirrigated land use in drier regions.Non-irrigated perennial grasses replace 

irrigated corn.

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. 

Air Quality Irrigated perennial grasses established with 

conventional tillage and grown with a short 

planting interval and chemical inputs 

replace land in the CRP.

Non-irrigated perennial grasses established 

with no till and grown with low chemical 

inputs and a long replanting interval replace 

irrigated corn grown with conventional 

tillage and high chemical inputs. 

Biodiversity Uniformly-managed perennial grasses 

established with conventional tillage and 

grown with a short planting interval and 

chemical inputs replace land in the CRP.

Perennial grasses grown with low chemical 

inputs replace corn grown with conventional 

tillage and high chemical inputs.

Invasiveness Switchgrass (west of the Rockies) and

Miscanthus are grown and become 

invasive or weedy.

Production of non-invasive native grasses or 

grass varieties bred for decreased 

invasiveness or weediness (e.g., sterile 

varieties).
Appendix C

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 C-7 DRAFT—DO NOT CITE OR QUOTE

Table C-1: 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 are 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.

10 
Appendix C

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

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.
Appendix C

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

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

Cellulosic 

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 possibly 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 
Appendix C

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

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-projected feedstock mix produced with 

conservation/best management practices (BMPs) and efficient 

technologies

Scenario B

2022 RFS2-projected feedstock mix 

produced with minimal 

conservation/BMPs and current 

technologies

Scenario C

2022 conventional feedstock mix (corn 

starch, corn stover, and soybean) 

produced with minimal 

conservation/BMPs and current 

technologies

Conventional Ethanol Corn Starch

15 BG

• No decrease in crop rotation with soybeans. • Increased use of continuous corn production and reduction in crop rotation.

• 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.

• 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.
Appendix C

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 C-11 DRAFT—DO NOT CITE OR QUOTE

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-projected feedstock mix produced with 

conservation/best management practices (BMPs) and efficient 

technologies

Scenario B

2022 RFS2-projected feedstock mix 

produced with minimal 

conservation/BMPs and current 

technologies

Scenario C

2022 conventional feedstock mix (corn 

starch, corn stover, and soybean) 

produced with minimal 

conservation/BMPs and current 

technologies

Cellulosic 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 on acreage 

regardless of erosion potential.

• Stover harvested with single-pass harvester. • Stover harvested with multi-pass harvester.

• Increased use of conservation practices. • No increase in use of conservation practices.

Woody 

Biomass

0.1 BG 0 BG

• Biomass produced via light-to-moderate 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 nonfederal 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 Rocky 

Mountains.

• Cellulosic feedstock (switchgrass or 

Miscanthus) produced on marginal 

land requiring high production 

inputs, including fertilizer, 

pesticides, and irrigation.

• 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.

• No increases in fuel conversion 

efficiency or reductions in fuel 

production inputs, including fresh 

water.
Appendix C

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

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-projected feedstock mix produced with 

conservation/best management practices (BMPs) and efficient 

technologies

Scenario B

2022 RFS2-projected feedstock mix 

produced with minimal 

conservation/BMPs and current 

technologies

Scenario C

2022 conventional feedstock mix (corn 

starch, corn stover, and soybean) 

produced with minimal 

conservation/BMPs and current 

technologies

Biomass-based 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.

• Increases in yield primarily due to higher production inputs, including 

fertilizer, pesticides, and irrigation.

• No conversion of marginal lands to soybean production. • Conversion of marginal lands to soybean production, including areas 

requiring irrigation.

• Increased use of conservation practices, including 

conservation tillage, nutrient management, and efficient 

irrigation delivery.

• 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.

• Algae produced on land converted 

from natural cover.

• Nutrient inputs from wastewater or other waste sources. • Large nutrient inputs from nonwaste sources.

• Closed bioreactors co-located with publicly owned 

treatment works and other wastewater treatment facilities.

• Open pond production using fresh 

water.

 12 
Appendix D

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-1 DRAFT—DO NOT CITE OR QUOTE

1 APPENDIX D:

2 

3 CONCEPTUAL MODELS

4 

5 
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-2 DRAFT—DO NOT CITE OR QUOTE

6 As described in this report, the activities associated with cultivation of biofuel feedstocks

7 and their conversion to fuel result in a complex set of inter-related environmental impacts. 

8 Conceptual models provide a useful tool to describe, understand, and communicate the complex 

9 pathways by which these activities lead to impacts. As noted in Chapter 7, EPA anticipates 

10 developing and using conceptual models as an important tool for the assessment in its 2013 

11 Report to Congress. The conceptual models presented in this appendix lay a foundation for this 

12 future effort. Figures D-1 to D-7 present conceptual models for feedstock cultivation and harvest. 

13 Figures D-8 and D-9 present models for biofuel production and distribution. (Note that models 

14 are not included for end use of biofuel.) These early renditions graphically present the 

15 environmental effects most commonly identified in current peer-reviewed literature and, while 

16 comprehensive, do not attempt to include all possible effects.

 17 

 19 

18 Feedstock Production 

20 Figures D-1 to D-7 present seven models for the six feedstocks covered in this report: 

21 corn starch; soybean; corn stover; perennial grass; woody biomass (short-rotation woody crops 

22 and forest thinning/residue removal); and algae production. 

23 Different pathways are introduced at the top of several of these feedstocks models. These 

24 pathways were selected because: (1) they will likely be pursued in combination in order to grow 

25 enough feedstock to meet RFS2 2022 biofuel requirements (see Chapter 2 for a description of 

26 requirements), and (2) they result in different environmental impacts. 

27 Arrows in the impact boxes (below the initial row of activities) depict whether the 

28 impacts are negative or positive. The number(s) by each arrow designate the pathway to which 

29 the arrows refer. A few pathways can have both negative and positive impacts (e.g., corn starch 

30 cultivation could result in increased or decreased use of ground and surface water). Dotted 

31 borders denote impacts that have a relatively large degree of uncertainty due to a lack of 

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 
Appendix D 

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

32 information. Dotted boxes without arrows depict highly uncertain impacts that nonetheless are 

33 described in the literature. 

35 

34 Fuel Production and Distribution

36 Figures D-8 and D-9 present conceptual models for production and distribution of the 

37 two biofuels covered in this report: ethanol and biodiesel.

38 Ethanol Production 

39 

40 Figure D-8 shows the activities and impacts associated with production and distribution 

41 of ethanol from both starch (i.e., corn grain) and cellulosic feedstocks, including corn stover, 

42 perennial grasses, and woody biomass. A single model is provided for these four types of 

43 feedstocks because their impacts and associated uncertainty are largely similar, with a few 

44 exceptions (e.g., water use will likely be slightly higher for cellulose conversion). 

45 As depicted in the upper left of the Figure D-8, conversion of starch to ethanol consists of 

46 several sequential steps, including milling, hydrolysis, and fermentation. There currently are two 

47 distinct alternatives for converting cellulosic feedstock into ethanol: (1) biochemical conversion 

48 (which is preceded by a catalysis step to separate cellulose and hemicellulose from their tightly 

49 bound state with lignin), and (2) thermochemical conversion. These alternatives vary slightly in 

50 terms of their chemical processes and by-products. As with Figures D-1 to D-7, a dotted border 

51 is used to denote impacts with relatively large uncertainty due to a lack of information. 

52 Biodiesel Production 

53 

54 Figure D-9 shows the activities and impacts associated with production of biodiesel from 

55 soybeans and algae. Several techniques may be used to convert plant oils into biodiesel, 

56 including hydrogenation, catalytic cracking, and transesterification. All these processes produce 

57 biodiesel, with glycerin as a by-product.
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-4 DRAFT—DO NOT CITE OR QUOTE

58 

59 

60 Figure D-1: Pathways for Potential Environmental Impacts of Corn Starch Feedstock Cultivation
Appendix D 

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

61 

62 

63 Figure D-2: Pathways for Potential Environmental Impacts of Soybean Feedstock Cultivation 

64 .
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-6 DRAFT—DO NOT CITE OR QUOTE

65 

66 

67 Figure D-3: Pathways for Potential Environmental Impacts of Corn Stover Feedstock Cultivation* 

68 *Corn stover is a waste product of corn starch cultivation. The impacts of corn cultivation are shown in Figure D-1. Figure D-3 highlights the 

69 environmental impacts of stover removal above and beyond those impacts attributable to corn grain production. 
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-7 DRAFT—DO NOT CITE OR QUOTE

70 

71 

72 Figure D-4: Pathways for Potential Environmental Impacts of Perennial Grass Feedstock Cultivation 
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-8 DRAFT—DO NOT CITE OR QUOTE

73 

74 

75 Figure D-5: Pathways for Potential Environmental Impacts of Short-Rotation Woody Crop Feedstock Cultivation 

76 *These particular land use changes may not currently be allowable under RFS2.
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-9 DRAFT—DO NOT CITE OR QUOTE

77 

78 

79 Figure D-6: Pathways for Potential Environmental Impacts of Forest Thinning and Residue Removal 
Appendix D 

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

80 

81 

82 Figure D-7: Potential Environmental Impacts of Algae Feedstock Production 
Appendix D 

This document is a draft for review purposes only and does not constitute Agency policy. 

1/19/11 D-11 DRAFT—DO NOT CITE OR QUOTE

83 

84 

85 Figure D-8: Potential Environmental Impacts of Producing and Distributing Conventional and Cellulosic Ethanol 

86 (Impacts of Fuel Use Not Included)
Appendix D

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

87 

88 

89 Figure D-9: Potential Environmental Impacts of Producing and Distributing Biodiesel 

90 (Impacts of Fuel Use Not Included)

 91