Comprehensive coverage on the growing science and technology of producing ethanol from the world's abundant cellulosic biomass
The inevitable decline in petroleum reserves and its impact on gasoline prices, combined with climate change concerns, have contributed to current interest in renewable fuels. Bioethanol is the most successful renewable transport fuel - with corn and sugarcane ethanol currently in wide use as blend-in fuels in the United States, Brazil, and a few other countries. However, there are a number of major drawbacks in these first-generation biofuels, such as their effect on food prices, net energy balance, and poor greenhouse gas mitigation. Alternatively, cellulosic ethanol can be produced from abundant lignocellulosic biomass forms such as agricultural or municipal wastes, forest residues, fast growing trees, or grasses grown in marginal lands, and should be producible in substantial amounts to meet growing global energy demand.
The Handbook of Cellulosic Ethanol covers all aspects of this new and vital alternative fuel source, providing readers with the background, scientific theory, and recent research progress in producing cellulosic ethanol via different biochemical routes, as well as future directions. The seventeen chapters include information on:
- Advantages of cellulosic ethanol over first-generation ethanol as a transportation fuel
- Various biomass feedstocks that can be used to make cellulosic ethanol
- Details of the aqueous phase or cellulolysis route, pretreatment, enzyme or acid saccharification, fermentation, simultaneous saccharification fermentation, consolidated bioprocessing, genetically modified microorganisms, and yeasts
- Details of the syngas fermentation or thermochemical route, gasifiers, syngas cleaning, microorganisms for syngas fermentation, and chemical catalysts for syngas-to-ethanol conversion
- Distillation and dehydration to fuel-grade ethanol
- Techno-economical aspects and the future of cellulosic ethanol
Readership
Chemical engineers, chemists, and technicians working on renewable energy and fuels in industry, research institutions, and universities. The Handbook can also be used by students interested in biofuels and renewable energy issues.
Table of Contents
Preface xvii
Part 1 Introduction to Cellulosic Ethanol 1
1 Renewable Fuels 3
1.1 Introduction 3
1.2 Renewable Energy 6
1.3 Biofuels 7
1.4 Renewable Energy in the United States 14
1.5 Renewable Fuel Legislature in the United States 20
References 25
2 Bioethanol as a Transportation Fuel 29
2.1 Introduction - History of Bioethanol as a Transportation Fuel 29
2.2 Alcohol Fuels 31
2.3 Fuel Characteristics of Ethanol 31
2.4 Corn and Sugarcane Ethanol 34
2.5 Advantages of Cellulosic Ethanol 35
References 40
3 Feedstocks for Cellulosic Ethanol Production 43
3.1 Introduction 43
3.2 Cellulosic Ethanol Feedstock Types 46
3.3 Potential of Agricultural Wastes 46
3.4 Major Crop Residue Feedstock 50
3.5 Forestry Residue, Logging and Mill Residue 68
3.6 Grass Feedstocks 70
3.7 Purpose-Grown Trees as Feedstock 92
3.8 Municipal and Other Waste as Feedstock for Cellulosic Ethanol 101
References 108
Part 2 Aqueous Phase Biomass Hydrolysis Route 131
4 Challenges in Aqueous-Phase Biomass Hydrolysis Route: Recalcitrance 133
4.1 Introduction – Two Ways to Produce Cellulosic Ethanol 133
4.2 Challenges in Aqueous-Phase Biomass Hydrolysis 134
4.3 Structure of Plant Cells and Lignocellulosic Biomass 135
4.4 Major Components of Lignocellulosic Biomass 137
4.5 Cellulose Recalcitrance 140
References 143
5 Pretreatment of Lignocellulosic Biomass 147
5.1 Introduction 147
5.2 Different Categories of Pretreatment Methods 150
5.3 Physical Pretreatment 150
5.4 Physicochemical Pretreatment 153
5.5 Chemical Pretreatment 177
5.6 Biological Pretreatment 190
5.7 Conclusion 191
References 197
6 Enzymatic Hydrolysis of Cellulose and Hemicellulose 219
6.1 Introduction 219
6.2 Enzymatic Actions on Lignocellulosic Biomass 220
6.3 Enzymatic Hydrolysis of Cellulose 221
6.4 Enzymatic Hydrolysis of Hemicellulose 233
6.5 Future Directions in Enzymatic Cellulose Hydrolysis Research 237
References 239
7 Acid Hydrolysis of Cellulose and Hemicellulose 247
7.1 Introduction 247
7.2 Concentrated Acid Hydrolysis 248
7.3 Dilute Acid Hydrolysis 252
7.4 Ionic Liquid-Based Direct Acid Hydrolysis 262
7.5 Solid Acid Hydrolysis 269
References 275
8 Fermentation I – Microorganisms 283
8.1 Introduction 283
8.2 Detoxification of Lignocellulosic Hydrolyzate 284
8.3 Separate Hydrolysis and Fermentation (SHF) 288
8.4 Microorganisms Used in the Fermentation 288
8.5 Fermentation Using Yeasts 289
8.6 Fermentation Using Bacteria 294
8.7 Simultaneous Saccharification and Fermentation (SSF) 300
8.8 Immobilization of Yeast 317
References 322
9 Fermentation II – Fermenter Configuration and Design 339
9.1 Introduction 339
9.2 Batch Fermentation 340
9.2.1 Examples of Batch Fermentation 340
9.3 Fed-Batch Fermentation 340
9.4 Continuous Fermentation 346
9.5 New Directions in Fermenter Configuration and Design 352
References 353
10 Separation and Uses of Lignin 357
10.1 Introduction 357
10.2 Structure of Lignin 359
10.3 Separation of Lignin in the Cellulosic Ethanol Process 360
10.4 Physical and Chemical Properties of Lignin 363
10.5 Applications of Lignin 365
10.5.1 Lignin-Based Phenol Formaldehyde Resins 365
References 373
Part 3 Biomass Gasification Route 381
11 Biomass Pyrolysis and Gasifier Designs 383
11.1 Introduction 383
11.2 Chemistry of the Conversion of Biomass to Syngas 384
11.3 Classifications of Biomass Gasifiers 387
11.4 Fixed-Bed Gasifier 388
11.5 Fluidized-Bed Gasifier 389
11.6 Bubbling Fluidized-Bed (BFB) Gasifier 390
11.7 Circulating Fluidized-Bed (CFB) Gasifier 392
11.8 Allothermal Dual Fluidized-Bed (DFB) Gasifier 392
11.9 Entrained-Flow Gasifier 395
11.10 Syngas Cleaning 396
11.11 Tar Control and Treatment Methods 403
References 403
12 Conversion of Syngas to Ethanol Using Microorganisms 407
12.1 Introduction 407
12.2 Metabolic Pathways 410
12.3 Microorganisms Used in Syngas Fermentation 414
12.4 Biochemical Reactions in Syngas Fermentation 414
12.5 The Effects of Operation Parameters on Ethanol Yield 416
12.6 Syngas Fermentation Reactors 424
12.7 Industrial-Scale Syngas Fermentation and Commercialization 426
References 427
13 Conversion of Syngas to Ethanol Using Chemical Catalysts 433
13.1 Introduction 433
13.2 Homogeneous Catalysts 434
13.3 Introduction to Heterogeneous Catalysts 437
13.4 Heterogeneous Catalyst Types 437
13.5 Rhodium-Based Catalysts 438
13.6 Copper-Based Modified Methanol Synthesis Catalysts 449
13.7 Modified Fischer-Tropsch-Type Catalysts 455
13.8 Molybdenum-Based Catalysts 456
13.9 Catalyst Selection 459
References 461
Part 4 Processing of Cellulosic Ethanol 467
14 Distillation of Ethanol 469
14.1 Introduction 469
14.2 Distillation of the Beer 470
14.3 How Distillation Works 470
14.4 Conventional Ethanol Distillation System 472
14.5 Steam Generation for Distillation Process 475
14.6 Studies on Development of Hybrid Systems for Ethanol Distillation 476
References 479
15 Dehydration to Fuel Grade Ethanol 481
15.1 Introduction 481
15.2 Dehydration Methods 482
15.3 Adsorption Method 482
15.4 Azeotropic Distillation Method 488
15.5 Extractive Distillation Methods 491
15.6 Membrane-Based Pervaporation Methods 494
15.7 Other Dehydration Methods 498
15.8 Comparisons of Common Dehydration Methods 498
References 500
Part 5 Fuel Ethanol Standards and Process Evaluation 507
16 Fuel Ethanol Standards, Testing and Blending 509
16.1 Introduction 509
16.2 Fuel Grade Ethanol Standards in the United States 510
16.3 Quality Assurance and Test Methods 514
16.4 European Fuel Ethanol Standards 517
16.5 Material Safety Data Sheet (MSDS) for Denatured Fuel Ethanol 518
16.6 Gasoline Ethanol Blends 520
16.7 Engine Performance Using Gasoline Ethanol Blends 524
References 528
17 Techno-Economic Analysis and Future of Cellulosic Ethanol 531
17.1 Introduction 531
17.2 Techno-Economic Aspects of Biomass Hydrolysis Process 532
17.3 Techno-Economic Aspects of Biomass Gasification Process 533
17.4 Comparison of Biomass Hydrolysis and Gasification Processes 539
17.5 Some Cellulosic Plants around the World 540
17.6 Challenges in Cellulosic Ethanol 550
17.7 Future Prospects of Cellulosic Ethanol 553
References 554
Appendix 1 557
Index
