Sugarcane-based Biofuels and Bioproducts

Sugarcane has garnered much interest for its potential as a viable renewable energy crop. While the use of sugar juice for ethanol production has been in practice for years, a new focus on using the fibrous co-product known as bagasse for producing renewable fuels and bio-based chemicals is growing in interest. The success of these efforts, and the development of new varieties of energy canes, could greatly increase the use of sugarcane and sugarcane biomass for fuels while enhancing industry sustainability and competitiveness.

Sugarcane-Based Biofuels and Bioproducts examines the development of a suite of established and developing biofuels and other renewable products derived from sugarcane and sugarcane-based co-products, such as bagasse. Chapters provide broad-ranging coverage of sugarcane biology, biotechnological advances, and breakthroughs in production and processing techniques.

Preface, xiii

List of contributors, xv

Part I Sugarcane for biofuels and bioproducts

1 The sugarcane industry, biofuel, and bioproduct perspectives, 3
Ian M. O’Hara

1.1 Sugarcane – a global bioindustrial crop, 3

1.2 The global sugarcane industry, 5

1.2.1 Sugarcane, 5

1.2.2 Sugarcane harvesting and transport, 6

1.2.3 The raw sugar production process, 7

1.2.4 The refined sugar production process, 9

1.2.5 The sugar market, 11

1.3 Why biofuels and bioproducts?, 11

1.3.1 The search for new revenue, 11

1.3.2 Sugar, ethanol, and cogeneration, 12

1.3.3 Fiber-based biofuels and bioproducts, 13

1.3.4 Climate change and renewable products, 13

1.3.5 New industries for sustainable regional communities, 14

1.4 Sugarcane biorefinery perspectives, 14

1.4.1 The sugarcane biorefinery, 14

1.4.2 The sustainability imperative, 17

1.4.3 Future developments in biotechnology for sugarcane biorefineries, 18

1.5 Concluding remarks, 19

References, 20

2 Sugarcane biotechnology: tapping unlimited potential, 23
Sudipta S. Das Bhowmik, Anthony K. Brinin, Brett Williams and Sagadevan G. Mundree

2.1 Introduction, 23

2.2 History of sugarcane, sugarcane genetics, wild varieties, 24

2.3 Uses of sugarcane, 25

2.3.1 Food and beverages, 25

2.3.2 Biofuels and bioenergy, 26

2.3.3 Fibers and textiles, 26

2.3.4 Value-added products, 26

2.4 Sugarcane biotechnology, 26

2.4.1 Limitations of sugarcane biotechnology, 29

2.5 Improvement of sugarcane – breeding versus genetic modification through biotechnology, 29

2.6 Genetic modification of sugarcane, 30

2.7 Paucity of high-quality promoters, 32

2.8 Opportunities for GM-improved sugarcane, 32

2.9 Improved stress tolerance and disease resistance, 35

2.9.1 Stress tolerance, 35

2.9.2 Drought, 35

2.9.3 Salinity, 35

2.10 Naturally resilient plants as a novel genetic source for stress tolerance, 36

2.11 Disease resistance, 37

2.12 Industrial application of sugarcane, 39

2.13 How will climate change and expanded growing-region affect vulnerability to pathogens?, 40

2.14 Conclusion and perspectives, 41

References, 42

Part II Biofuels and bioproducts

3 Fermentation of sugarcane juice and molasses for ethanol production, 55
Cecília Laluce, Guilherme R. Leite, Bruna Z. Zavitoski, Thamires T. Zamai

and Ricardo Ventura

3.1 Introduction, 55

3.2 Natural microbial ecology, 56

3.2.1 Saccharomyces yeasts, 56

3.2.2 Wild yeasts, 58

3.2.3 Bacterial contaminants, 58

3.3 Yeast identification, 60

3.3.1 Identification of genetic and physiological phenotypes, 60

3.3.2 Molecular identification methods, 61

3.4 Cell surface and cell–cell interactions, 62

3.4.1 Dissolved air flotation, 62

3.4.2 Flocculation, 64

3.4.3 Biofilms, 65

3.5 Sugarcane juice and bagasse, 65

3.5.1 Harvesting of the sugarcane, 65

3.5.2 Reception and cleaning of sugarcane, 66

3.5.3 Juice extraction, 66

3.5.4 Juice clarification, 66

3.5.5 Juice concentration, 66

3.5.6 Quality of clarified juice, 67

3.6 Fermentation of juice and molasses, 67

3.6.1 Starters yeasts, 67

3.6.2 Raw materials used in fermentation, 67

3.6.3 The fermentation, 68

3.7 Cogeneration of energy from bagasse, 68

3.8 Bioreactors and processes, 69

3.8.1 Batch fermentation, 70

3.8.2 Fed-batch fermentation, 70

3.8.3 Multistage Stage Continuous Fermentation (MSCF) system, 72

3.9 Control of microbial infections, 73

3.10 Monitoring and controlling processes, 74

3.11 Concluding remarks and perspective, 76

Acknowledgments, 77

References, 77

4 Production of fermentable sugars from sugarcane bagasse, 87
Zhanying Zhang, Mark D. Harrison and Ian M. O’Hara

4.1 Introduction, 87

4.2 Bioethanol from bagasse, 88

4.3 Overview of pretreatment technologies, 90

4.4 Pretreatment of bagasse, 91

4.4.1 Dilute acid pretreatment, 91

4.4.2 Alkaline pretreatment, 92

4.4.3 Liquid hot water pretreatment, 93

4.4.4 Organosolv pretreatment, 94

4.4.5 Ionic liquid pretreatment, 97

4.4.6 SO2- and CO2-associated pretreatments, 98

4.5 Enzymatic hydrolysis, 99

4.6 Fermentation, 100

4.7 Conclusions and future perspectives, 102

References, 103

5 Chemicals manufacture from fermentation of sugarcane products, 111
Karen T. Robins and Robert E. Speight

5.1 Introduction, 111

5.2 The suitability of sugarcane-derived feedstocks in industrial fermentation processes, 114

5.2.1 Competing current applications of sugarcane products, 115

5.2.2 Use of sugarcane products in fermentations, 117

5.3 Metabolism and industrial host strains, 121

5.3.1 Metabolism of sucrose, 121

5.3.2 Metabolism of lignocellulose-derived sugars, 124

5.3.3 Optimization of strains and metabolism, 126

5.4 Bioprocess considerations, 127

5.5 Sugarcane-derived chemical products, 130

5.6 Summary, 132

References, 133

6 Mathematical modeling of xylose production from hydrolysis of sugarcane bagasse, 137
Ava Greenwood, Troy Farrell and Ian M. O’Hara

6.1 Introduction, 137

6.2 Mathematical models of hemicellulose acid pretreatment, 139

6.2.1 Kinetic models of hemicellulose acid hydrolysis, 139

6.2.2 The Saeman kinetic model, 139

6.2.3 The biphasic model, 140

6.2.4 The polymer degradation equation, 143

6.2.5 Other mathematical considerations and models of hemicellulose acid hydrolysis, 146

6.3 A mathematical model of sugarcane bagasse dilute-acid hydrolysis, 150

6.4 Sensitivity analysis, 153

6.4.1 Experimental solids loadings and fitting the hard-to-hydrolyze parameter, 155

6.4.2 Hemicellulose chain length characteristics and the parameter fitting of ka and kb, 156

6.5 Conclusions, 159

References, 160

7 Hydrothermal liquefaction of lignin, 165
Kameron G. Dunn and Philip A. Hobson

7.1 Introduction, 165

7.2 A review of lignin alkaline hydrolysis research, 170

7.3 Hydrolysis in subcritical and supercritical water without an alkali base, 186

7.4 Solvolysis with hydrogen donor solvent formic acid, 188

7.5 Reported depolymerization pathways of lignin and lignin model compounds, 192

7.6 The solid residue product, 194

7.7 Summary – strategies to increase yields of monophenols, 195

7.7.1 Reaction temperature, 200

7.7.2 Reaction pressure, 201

7.7.3 Reaction time, 201

7.7.4 Lignin loading, 202

7.7.5 Alkali molarity, 202

7.7.6 Monomer separation, 202

7.7.7 Lignin structure, 202

References, 203

8 Conversion of sugarcane carbohydrates into platform chemicals, 207
Darryn W. Rackemann, Zhanying Zhang and William O.S. Doherty

8.1 Introduction, 207

8.1.1 Bagasse, 208

8.1.2 Biorefining, 208

8.2 Platform chemicals, 210

8.2.1 Furans, 212

8.2.2 Furfural, 212

8.2.3 HMF, 214

8.3 Organic acids, 214

8.3.1 Levulinic acid, 214

8.3.2 Formic acid, 218

8.4 Value of potential hydrolysis products, 218

8.5 Current technology for manufacture of furans and levulinic acid, 220

8.6 Technology improvements, 222

8.7 Catalysts, 223

8.7.1 Homogeneous catalysts, 223

8.7.2 Heterogeneous catalysts, 224

8.7.3 Levulinic acid, 224

8.8 Solvolysis, 226

8.9 Other product chemicals, 228

8.9.1 Esters, 228

8.9.2 Ketals, 228

8.9.3 Chloromethylfurfural, 229

8.9.4 GVL, 229

8.10 Concluding remarks, 230

References, 231

9 Cogeneration of sugarcane bagasse for renewable energy production, 237
Anthony P. Mann

9.1 Introduction, 237

9.2 Background, 238

9.3 Sugar factory processes without large-scale cogeneration, 243

9.4 Sugar factory processes with large-scale cogeneration, 249

9.4.1 Reducing LP steam heating requirements, 249

9.4.2 Reducing boiler station losses, 251

9.4.3 Increasing power generation efficiency, 253

9.4.4 A sugar factory cogeneration steam cycle, 254

9.5 Conclusions, 256

References, 257

10 Pulp and paper production from sugarcane bagasse, 259
Thomas J. Rainey and Geoff Covey

10.1 Background, 259

10.2 History of bagasse in the pulp and paper industry, 260

10.3 Depithing, 260

10.3.1 The need for depithing, 260

10.3.2 Depithing operation, 262

10.3.3 Character of pith, depithed bagasse, and whole bagasse, 264

10.3.4 Combustion of pith, 264

10.4 Storage of bagasse for papermaking, 266

10.5 Chemical pulping and bleaching of bagasse, 268

10.5.1 Digestion, 268

10.5.2 Black liquor, 269

10.5.3 Bleaching, 270

10.6 Mechanical and chemi-mechanical pulping, 271

10.7 Papermaking, 272

10.7.1 Fiber morphology, 272

10.7.2 Suitability of bagasse for various paper grades, 273

10.7.3 Physical properties, 274

10.7.4 Effect of pith on paper production, 275

10.8 Alternate uses of bagasse pulp, 276

References, 277

11 Sugarcane-derived animal feed, 281
Mark D. Harrison

11.1 Introduction, 281

11.1.1 The anatomy of the sugarcane plant, 282

11.1.2 Sugarcane production, processing, and sugar refining, 282

11.1.3 Scope of the chapter, 284

11.2 Crop residues and processing products, 285

11.2.1 Whole sugarcane, 285

11.2.2 Tops and trash, 286

11.2.3 Bagasse, 288

11.2.4 Molasses, 288

11.2.5 Sugarcane juice, 290

11.3 Processing sugarcane residues to enhance their value in animal feed, 290

11.3.1 Ensilage/microbial conditioning, 291

11.3.2 Chemical conditioning, 293

11.3.3 Physical processing (baling, pelletization, depithing), 296

11.3.4 Pretreatment, 296

11.4 Conclusions, 300

References, 300

Part III Systems and sustainability

12 Integrated first- and second-generation processes for bioethanol production from sugarcane, 313
Marina O. de Souza Dias, Otávio Cavalett, Rubens M. Filho and Antonio Bonomi

12.1 Introduction, 313

12.2 Process descriptions, 315

12.2.1 First-generation ethanol production, 315

12.2.2 Second-generation ethanol production, 317

12.2.3 Cogeneration in integrated first- and second-generation ethanol production from sugarcane, 320

12.2.4 Some aspects of the process integration, 321

12.3 Economic aspects of first- and second-generation ethanol production, 323

12.4 Environmental aspects of first- and second-generation ethanol production, 325

12.5 Final remarks, 328

References, 328

13 Greenhouse gas abatement from sugarcane bioenergy, biofuels, and biomaterials, 333
Marguerite A. Renouf

13.1 Introduction, 333

13.2 Life cycle assessment (LCA) of sugarcane systems, 335

13.2.1 Overview of LCA and carbon footprinting, 335

13.2.2 Past LCA and carbon footprint studies of sugarcane bioproducts, 337

13.3 Greenhouse gas/carbon footprint profile of sugarcane bioproducts, 339

13.3.1 Land use change, 339

13.3.2 Sugarcane production, 340

13.3.3 Sugarcane biorefining, 342

13.3.4 Downstream phases, 343

13.4 Greenhouse gas (GHG) abatement from sugarcane products, 343

13.4.1 Comparing sugarcane products with fossil fuel products, 343

13.4.2 Influence of land-use change, 344

13.4.3 Comparing sugarcane with other biomass feedstock, 345

13.4.4 Attributes for GHG abatement, 348

13.5 Environmental trade-offs, 349

13.5.1 Land use and associated environmental services, 349

13.5.2 Water use, 350

13.5.3 Water quality, 350

13.5.4 Phosphorus depletion, 351

13.5.5 Balancing the GHG abatement benefits with the environmental trade-offs, 351

13.6 Production pathways that optimize GHG abatement, 352

13.6.1 Production basis (dedicated vs. coproduction), 352

13.6.2 Product outputs, 352

13.6.3 Land used, 354

13.7 Opportunities for further optimizing GHG abatement, 354

13.7.1 Ecoefficient sugarcane growing, 354

13.7.2 Utilization of harvest residues, 355

13.7.3 New sugarcane varieties, 355

13.8 Summary, 355

References, 356

14 Environmental sustainability assessment of sugarcane bioenergy, 363
Shabbir H. Gheewala, Sébastien Bonnet and Thapat Silalertruksa

14.1 Bioenergy and the sustainability challenge, 363

14.2 Prospect of sugarcane bioenergy, 364

14.3 Environmental sustainability assessment tools, 365

14.4 Environmental sustainability assessment of sugarcane bioenergy: Case of Thailand, 366

14.4.1 Background and policy context, 366

14.4.2 Sugarcane farming and production system, 366

14.4.3 Sugarcane farming and harvesting, 367

14.4.4 Sugarcane milling, 367

14.4.5 Ethanol conversion, 368

14.4.6 Transport, 368

14.5 Net energy balance and net energy ratio, 369

14.6 Life cycle environmental impacts, 369

14.7 Key environmental considerations for promoting sugarcane bioenergy, 372

References, 376

Index, 379

Ian O'Hara is Associate Professor of Process Engineering with the Centre for Tropical Crops and Biocommodities at Queensland University of Technology in Brisbane, Australia

Sagadevan Mundree is Professor and Director of the Centre for Tropical Crops and Biocommodities at Queensland University of Technology in Brisbane, Australia