Plant Biomass Conversion

Contributors xi

Preface xiii

1 The Bioeconomy: A New Era of Products Derived from Renewable Plant-Based Feedstocks 3
Peter Nelson, Elizabeth Hood, and Randall Powell

1.1 Introduction 3

1.2 Market Opportunity for Biofuels and Biobased Products 5

1.3 Feedstocks 6

1.3.1 Biobased Feedstock Availability and Issues 6

1.3.2 Characterization of Lignocellulosic Feedstocks 8

1.3.3 The Role of Agricultural Biotechnology 9

1.3.4 Biomass Agricultural Equipment Development 11

1.4 The Biochemical Technology Platform 11

1.5 Investment and Major Players 12

1.6 The Role of the Farmer 14

1.7 Opportunities for Rural Development 16

1.8 Environmental Benefits 17

1.9 Economic Comparison of the Biochemical and Thermochemical Technology Platforms 17

1.10 Conclusions and Future Prospects 18

References 19

2 Agricultural Residues 21
James Hettenhaus

2.1 Introduction 21

2.1.1 Key Issues 22

2.2 Feedstock Supply 23

2.2.1 Residue Markets 26

2.2.2 Harvest Window 27

2.2.3 Residue Removal 27

2.2.4 Residue Management 28

2.2.5 Ag Equipment Needs 29

2.2.6 Operating Costs 33

2.2.7 Residue Nutrient Value 33

2.2.8 Land for Energy Crops 33

2.2.9 Farmer Outlook 34

2.2.10 Crop Research and Development 34

2.3 Feedstock Logistics 34

2.3.1 Bulk Density 35

2.3.2 Storage 36

2.3.3 Regional Biomass Processing Centers 43

2.4 Conclusion 48

Endnotes 49

References 49

3 Growing Systems for Traditional and New Forest-Based Materials 51
Randall Rousseau, Janet Hawkes, Shijie Liu, and Tom Amidon

3.1 Introduction 51

3.2 Natural Regeneration 54

3.3 Overall Growing Systems 54

3.3.1 The Beginnings of Biomass Plantation Production 55

3.3.2 Short Rotation Woody Crops 56

3.3.3 Other Types of Hardwood Plantations 59

3.3.4 Southern Pine 61

3.4 New Genetic Tools 62

3.5 Agroforestry 63

3.6 Products from Woody Biomass 67

3.6.1 Hemicellulosic Products 69

3.6.2 Biorefineries Using Woody Biomass 71

3.6.3 Hot-Water Extraction of Hemicellulose 73

3.6.4 Wood Extracts: Processing and Conversion 75

3.6.5 Residual Solid Wood Biomass: Processing and Conversion of the wood mass after extraction, an example 78

3.7 Summary 78

References 78

4 Dedicated Herbaceous Energy Crops 85
Keat (Thomas) Teoh, Shivakumar Pattada Devaiah, Deborah Vicuna Requesens, and Elizabeth E. Hood

4.1 Introduction 85

4.2 Miscanthus 85

4.2.1 Characteristics That Make Miscanthus a Potential Biomass Crop 87

4.2.2 Agronomy 87

4.3 Sweet Sorghum 90

4.3.1 Biology of Sweet Sorghum 92

4.3.2 Production 92

4.3.3 Potential Yields 94

4.3.4 Economic and Environmental Advantages of Sweet Sorghum 94

4.3.5 Production Challenges 96

4.4 Switchgrass 97

4.4.1 Physiology 97

4.4.2 Switchgrass Ecotypes 98

4.4.3 Advantages 98

4.4.4 Disadvantages 99

4.4.5 Yields 100

4.4.6 Switchgrass as a Bioenergy Crop 101

4.5 Conclusions and Future Prospects 101

References 104

5 Municipal Solid Waste as a Biomass Feedstock 109
David J. Webster

5.1 Introduction 109

5.2 Definitions 110

5.2.1 Second-Generation Conversion Technologies for Biofuels 110

5.3 Disposal Infrastructure and Transfer Stations 110

5.3.1 Collection Practices 112

5.3.2 Cost Parameters 112

5.4 Waste Generation 113

5.5 Waste Characterization 114

5.5.1 Composition of Generated MSW Prior to Disposal or Processing 114

5.5.2 Landfilled Waste Compared to Waste Generation 115

5.5.3 Water in MSW 116

5.5.4 Heavy Metals in MSW 117

5.6 Preparing MSW for Conversion Processing—Mixed Waste Material Recovery Facilities (MRFs) 119

5.6.1 Presorting 121

5.6.2 Mechanical Sorting Operations 122

5.6.3 Manual Sorting Operations 123

5.6.4 Recovery Rates of the MRF System 123

5.7 Cellulosic Content of MSW 124

5.7.1 Glucose and Ethanol Yields from MSW 124

5.8 Framing the Potential 125

References 126

6 Water Sustainability in Biomass Cropping Systems 129
Jennifer L. Bouldin and Rodney E. Wright

6.1 Introduction 129

6.2 Water Use in Bioenergy Production 130

6.3 Water Quality Issues in Bioenergy Crops 133

6.3.1 AGNPS Watershed Model 135

6.3.2 Water Quality and the Gulf Hypoxic Zone 138

6.4 Conclusions—Water Quantity and Quality 138

References 139

7 Soil Sustainability Issues in Energy Crop Production 143
V. Steven Green

7.1 Soil Sustainability Concepts 143

7.2 Bioenergy Crops and Soil Sustainability 145

7.2.1 Crop Residues 145

7.2.2 Dedicated Energy Crops 146

7.3 Resource Use in Biomass Production 149

7.3.1 Water and Soil 149

7.3.2 Land Use 150

7.4 Soil Sustainability Solutions 150

7.5 Conclusion 154

References 154

8 Fermentation Organisms for 5- and 6-Carbon Sugars 157
Nicholas Dufour, Jeffrey Swana, and Reeta P. Rao

8.1 Introduction 157

8.2 Fermentation 159

8.3 Metabolic Pathways 160

8.4 Fermenting Species 161

8.4.1 Brief Description of Major Species 175

8.5 Other Relevant Products 180

8.6 Summary 183

Endnotes 183

References 184

9 Pretreatment Options 199
Bradley A. Saville

9.1 Overview of Pretreatment Technologies 199

9.1.1 History 199

9.1.2 Mechanistic Assessment of Pretreatment 200

9.1.3 Severity Factor Concept 203

9.2 Pretreatment Classification 205

9.2.1 Mechanical Pretreatment Processes 206

9.2.2 Chemical Pretreatment Processes 206

9.2.3 Thermochemical Pretreatment Processes 209

9.2.4 Impact on Moisture Content and Hydraulic Load 210

9.3 Laboratory vs. Commercial Scale Pretreatment—What Do We Really Know? 211

9.3.1 Laboratory Studies 211

9.3.2 Pilot/Demonstration Scale Studies 211

9.3.3 Limitations of Laboratory-Scale Comparisons of Pretreatment Methods 214

9.4 Process Issues and Trade-Offs 215

9.4.1 Inhibitors 215

9.4.2 Hydrolysis Efficiency and Enzyme Loadings 218

9.4.3 Solvent/Catalyst Recovery 218

9.4.4 Viscosity Reduction and Hydraulic Load 218

9.5 Economics 220

9.6 Conclusions 224

References 224

10 Enzyme Production Systems for Biomass Conversion 227
John A. Howard, Zivko Nikolov, and Elizabeth E. Hood

10.1 Introduction 227

10.2 The Challenge: Volume and Cost of Enzymes Required 227

10.3 Theoretical Ways to Address the Challenge of Quantity of Enzyme and Cost Requirements 228

10.3.1 Increase Susceptibility for Biomass Deconstruction 229

10.3.2 Decrease Exogenous Enzyme Load 231

10.3.3 Increase Accumulation of Enzymes in Production Host 236

10.4 Cost of Producing Exogenous Enzymes 240

10.4.1 Cost Analysis 242

10.5 Summary and Future Prospects 245

References 246

11 Fermentation-Based Biofuels 255
Randy Kramer and Helene Belanger

11.1 Introduction 255

11.2 First-Generation Biofuels 256

11.2.1 Starch-Based Ethanol—United States 256

11.2.2 Sugar-Based Ethanol—Brazil 257

11.2.3 Biodiesel 258

11.3 Policy and Biofuel Implementation Status 260

11.3.1 North America 260

11.3.2 South America 262

11.3.3 Europe 262

11.3.4 Asia 263

11.4 Second-Generation Biofuels 265

11.4.1 Cellulosic Ethanol 265

11.4.2 Biobutanol 268

11.5 Issues for Biofuels Commercial Success 269

11.5.1 Transport by Pipeline 269

11.5.2 Decentralized Production and Local Distribution 270

11.5.3 Optimized Engine Performance 271

11.5.4 Value of Biorefinery Co-products 272

11.6 Summary 272

References 272

12 Biobased Chemicals and Polymers 275
Randall W. Powell, Clare Elton, Ross Prestidge, and Helene Belanger

12.1 Introduction 275

12.2 Biobased Feedstock Components 276

12.3 Biomass Conversion Technologies 277

12.3.1 Technology Platforms Overview 277

12.3.2 Lignocellulose Fractionation Overview 279

12.4 Biobased Products 287

12.4.1 Oil-Based Products 287

12.4.2 Sugar/Starch-Based Products 289

12.4.3 Polymer Products 293

12.4.4 Lignin Products 299

12.5 Summary 303

References 304

13 Carbon Offset Potential of Biomass-Based Energy 311
Gauri-Shankar Guha

13.1 Emerging Public Interest in Carbon 311

13.1.1 Overview 311

13.1.2 Initiatives to Address Anthropogenic Climate Change 311

13.1.3 GHG Mitigation and Carbon Sequestration Strategies 314

13.2 Theory of Carbon Markets 314

13.2.1 Tradable Permits and the Market for Emissions 314

13.2.2 Concept of Carbon Markets 315

13.2.3 Demand and Supply of Carbon Credits 316

13.3 Creation of Carbon Markets 317

13.3.1 Carbon Credits 317

13.3.2 Global Carbon Trade 318

13.3.3 Carbon Trading in the United States 318

13.3.4 The CCX Offset Program 318

13.4 Role of Biomass-Based Energy in Carbon Markets 319

13.4.1 Economic Significance of Bioenergy 319

13.4.2 Bioenergy Policies, Practices, and Trends 321

13.4.3 Carbon Offset Opportunities for Biofuels 323

13.5 Prognosis of Carbon Markets 324

References 325

14 Biofuel Economics 329
Daniel Klein-Marcuschamer, Brad Holmes, Blake A. Simmons, and Harvey W. Blanch

14.1 Introduction 329

14.2 Production Processes 330

14.3 Biomass Transportation and Handling 331

14.4 Conversion of Biomass into Sugars 332

14.5 Conversion of Sugars into Biofuels 335

14.6 Separation and Purification 337

14.7 Co-product Handling 337

14.8 Major Cost Drivers 338

14.8.1 Biomass-Associated Costs 338

14.8.2 Capital Expenses 340

14.8.3 Operating Costs 342

14.9 Risks 343

14.10 Policy Support 345

14.11 Infrastructure and Vehicle Modifications 346

14.12 Conclusions 347

14.13 Acknowledgments 348

References 348

Index 355