Process Synthesis for Fuel Ethanol Production Book

Preface xv

Acknowledgments xvii

The Authors xix

Chapter 1 Biofuels 1

1.1 Biofuels Generalities 1

1.1.1 Solid and Gaseous Biofuels 3

1.1.2 Liquid Biofuels 4

1.1.2.1 Biodiesel 4

1.1.2.2 Bioethanol 5

1.2 Gasoline Oxygenation 5

1.2.1 Tetraethyl Lead as Antiknocking Additive 8

1.2.2 Ethers as Gasoline Oxygenates 8

1.2.2.1 Methyl Tert-Butyl Ether (MTBE) 9

1.2.2.2 Ethyl Tert-Butyl Ether (ETBE) 10

1.2.2.3 Tert-Amyl Methyl Ether (TAME) and Tert-Amyl Ethyl Ether (TAEE) 11

1.2.2.4 Di-Isopropyl Ether (DIPE) 11

1.2.3 Methanol 12

1.3 Ethanol as a Gasoline Oxygenate 12

1.3.1 Advantages of Fuel Ethanol 13

1.3.2 Drawbacks of Fuel Ethanol 14

1.4 Gasoline Oxygenation Programs with Fuel Ethanol in Some Countries 17

References 22

Chapter 2 Process Design and Role of Process Synthesis 27

2.1 Conceptual Process Design 27

2.2 Knowledge-Based Process Synthesis 30

2.2.1 Evolutionary Modification 31

2.2.2 Hierarchical Decomposition 32

2.2.3 Phenomena-Driven Design 33

2.2.4 Conflict-Based Approach 33

2.2.5 Thermodynamics-Based Process Synthesis 33

2.2.6 Analysis of the Statics 34

2.3 Optimization-Based Process Synthesis 35

2.3.1 Mathematical Aspects 36

2.3.2 Superstructures 38

2.3.3 Hybrid Methods 39

2.4 Final Considerations 40

References 40

Chapter 3 Feedstocks for Fuel Ethanol Production 43

3.1 Sugars 43

3.1.1 Sugarcane 43

3.1.2 Cane Sugar 45

3.1.3 Sugar Beet 48

3.1.4 Beet Sugar 48

3.1.5 Sucrose-Containing Materials Used for Ethanol Production 50

3.1.5.1 Cane and Beet Juices 51

3.1.5.2 Sugarcane Molasses 51

3.1.5.3 Beet Molasses 52

3.1.5.4 Other Sugar-Containing Materials 52

3.2 Starchy Materials 53

3.2.1 Starch53

3.2.2 Starch Sources for Ethanol Production 55

3.2.2.1 Corn 56

3.2.2.2 Other Grains as Starch Sources 59

3.2.2.3 Cassava 60

3.3 Lignocellulosic Materials 61

3.3.1 Structure of Lignocellulosic Complex 62

3.3.2 Classification of Lignocellulosic Materials 63

3.3.2.1 Sugarcane Bagasse 68

3.3.2.2 Corn Stover 69

3.3.2.3 Cereal Straws 70

3.3.2.4 Municipal Solid Waste 70

References 71

Chapter 4 Feedstock Conditioning and Pretreatment 77

4.1 Conditioning of Sucrose-Containing Materials 77

4.2 Pretreatment of Starchy Materials 80

4.3 Pretreatment of Lignocellulosic Biomass 83

4.3.1 Physical Methods of Pretreatment 84

4.3.2 Physical-Chemical Methods of Pretreatment 85

4.3.3 Chemical Methods of Pretreatment 90

4.3.4 Biological Methods of Pretreatment 95

4.3.5 Role of Pretreatment during Process Synthesis 95

4.4 Detoxification of Pretreated Biomass 98

4.4.1 Physical Methods of Detoxification 100

4.4.2 Chemical Methods of Detoxification 100

4.4.3 Biological Methods of Detoxification 105

References 108

Chapter 5 Hydrolysis of Carbohydrate Polymers 115

5.1 Starch Saccharification 115

5.2 Hydrolysis of Cellulose 117

5.2.1 Enzyme Systems for Cellulose Hydrolysis 118

5.2.2 Conversion of Cellulose to Glucose 122

5.2.3 Cellulose Hydrolysis Assessment for Process Synthesis 123

5.2.3.1 Efficiency of Cellulases 123

5.2.3.2 Modeling of Cellulose Hydrolysis 124

References 126

Chapter 6 Microorganisms for Ethanol Production 131

6.1 Metabolic Features of Ethanol Producing Microorganisms 151

6.2 Nongenetically Modified Microorganisms for Ethanol Production 134

6.2.1 Yeasts 136

6.2.2 Bacteria 138

6.3 Genetically Modified Microorganisms for Ethanol Production 140

6.3.1 Mutagenesis 140

6.3.2 Recombinant DNA Technology 141

6.3.2.1 Recombinant Microorganisms for Starch Processing 143

6.3.2.2 Recombinant Microorganisms for Processing of Lignocellulosic Biomass 148

References 151

Chapter 7 Ethanolic Fermentation Technologies 155

7.1 Description of Main Fermentation Technologies for Ethanol Production 155

7.1.1 Features of Ethanolic Fermentation Using Saccharomyces cerevisiae 155

7.1.2 Fermentation of Sucrose-Based Media 156

7.1.2.1 Batch Fermentation 157

7.1.2.2 Semicontinuous Fermentation 158

7.1.2.3 Continuous Fermentation 161

7.1.2.4 Fermentation of Sugar Solutions Using Immobilized Cells 163

7.1.3 Fermentation of Media Based on Starchy Materials 166

7.1.3.1 Conversion of Saccharified Corn Starch into Ethanol 166

7.1.3.2 Very High Gravity Fermentation 167

7.1.4 Fermentation of Media Based on Lignocellulosic Biomass 168

7.1.4.1 Fermentation of Cellulose Hydrolyzates 168

7.1.4.2 Pentose Fermentation 170

7.1.4.3 Co-Fermentation of Lignocellulosic Hydrolyzates 171

7.2 Modeling of Ethanolic Fermentation for Process Design Purposes 173

7.2.1 Modeling of Ethanolic Fermentation from Sugars 176

7.2.2 Modeling of Co-Fermentation of Hexoses and Pentoses 179

7.3 Analysis of Fed-Batch Ethanolic Fermentation 181

7.4 Dynamics of Continuous Fermentation Systems 182

References 191

Chapter 8 Analysis of Ethanol Recovery and Dehydration 199

8.1 Concentration and Rectification of Ethanol Contained in Culture Broths 199

8.2 Ethanol Dehydration 201

8.2.1 Pressure-Swing Distillation 202

8.2.2 Azeotropic Distillation 202

8.2.3 Extractive Distillation 206

8.2.4 Saline Extractive Distillation 209

8.2.5 Adsorption 210

8.2.6 Pervaporation 211

8.3 Evaluation of Separation and Dehydration Schemes 213

References 217

Chapter 9 Integrated Processes for Fuel Ethanol Production 221

9.1 Process Integration 221

9.2 Reaction-Reaction Integration for Bioethanol Production 224

9.2.1 Process Integration by Co-Fermentation 224

9.2.2 Process Integration by SSF 225

9.2.2.1 SSF of Starch 225

9.2.2.2 SSYPF of Starchy Materials 230

9.2.2.3 SSF of Lignocellulosic Materials 231

9.2.2.4 Modeling of SSF of Cellulose 235

9.2.3 Process Integration by SSCF 240

9.2.4 Process Integration by Consolidated Bioprocessing 241

9.3 Reaction-Separation Integration for Bioethanol Production 244

9.3.1 Ethanol Removal by Vacuum 246

9.3.2 Ethanol Removal by Gas Stripping 246

9.3.3 Ethanol Removal by Membranes 249

9.3.4 Ethanol Removal by Liquid Extraction 263

9.4 Separation-Separation Integration for Bioethanol Production 275

References 276

Chapter 10 Environmental Aspects of Fuel Ethanol Production 285

10.1 Effluent Treatment during Fuel Ethanol Production 285

10.1.1 Residues Generated in the Process of Bioethanol Production 285

10.1.2 Methods for Treatment and Utilization of Stillage 286

10.1.2.1 Stillage Recycling 287

10.1.2.2 Stillage Evaporation 289

10.1.2.3 Solids Recovery 289

10.1.2.4 Stillage Incineration 289

10.1.2.5 Fertilization 290

10.1.2.6 Anaerobic Digestion 290

10.1.2.7 Composting 291

10.1.2.8 Stillage as a Culture Medium 292

10.1.2.9 Stillage Oxidation 292

10.1.2.10 Wastewater Treatment of Biomass-to-Ethanol Process 293

10.2 Environmental Performance of Fuel Ethanol Production 298

10.2.1 WAR Algorithm 299

10.2.2 Life Cycle Assessment of Bioethanol Production 304

10.2.3 Other Methodologies for the Environmental Analysis of Bioethanol Production 306

References 307

Chapter 11 Technological Configurations for Fuel Ethanol Production in the Industry 311

11.1 Ethanol Production from Sucrose-Containing Materials 311

11.2 Ethanol Production from Starchy Materials 322

11.2.1 Configuration Involving the Separate Hydrolysis and Fermentation (SHF) of Corn Starch 322

11.2.2 Configuration Involving the Simultaneous Saccharification and Fermentation (SSF) of Corn Starch 325

11.2.3 Configuration for Production of Cassava Ethanol 333

11.3 Ethanol Production from Lignocellulosic Materials 336

11.3.1 Process Flowsheet Development for Production of Biomass Ethanol 337

11.3.2 Optimization-Based Process Synthesis for Ethanol Production from Biomass 348

11.4 Role of Energy Integration during Process Synthesis 351

References 353

Chapter 12 Food Security versus Fuel Ethanol Production 359

12.1 Crop Potentials for Food and Energy 359

12.1.1 Corn in the United States 360

12.1.2 Sugarcane in Colombia 361

12.1.3 Sugarcane in Brazil 362

12.1.4 Sugarcane in Tanzania 363

12.1.5 Lignocellulosics: Nonfood Alternative 364

12.2 Bioethanol and Fossil Oil Dependence 365

12.3 Bioenergy and Transgenics 366

12.4 Bioenergy and Food Market 366

12.5 Bioenergy and Food Security Project 368

12.5.1 The BEFS Project is Developed in Basic Phases 369

12.5.2 Purposes and Activities of Modules 369

12.5.2.1 Module 1 369

12.5.2.2 Module 2 370

12.5.2.3 Module 3 371

12.5.2.4 Module 4 371

12.5.2.5 Module 5 371

12.5.2.6 Module 6 371

12.5.3 Preliminary BEFS Results for Tanzania 372

12.6 Concluding Remarks 375

References 376

Chapter 13 Perspectives and Challenges in Fuel Ethanol Production 379

13.1 Feedstocks 379

13.2 Process Engineering 380

13.3 Food Security Impacts 384

13.4 Environmental Impacts 387

Index 391