Biofuels and Bioenergy

About the Editors John Love and John A. Bryant, Biosciences, College Of Life and Environmental Sciences, University of Exeter, UK

List of Contributors xiii


Preface xv


List of Abbreviations xix


1 Biofuels: The Back Story 1
John A. Bryant and John Love


Summary 1


1.1 Introduction 1


1.2 Some history 1


1.2.1 Wood and charcoal 1


1.2.2 Dung as fuel 2


1.2.3 Oils and fats 2


1.2.4 Peat 3


1.3 Fossil fuels 4


1.3.1 Coal 4


1.3.2 Petroleum Oil 5


1.3.3 Natural gas 6


1.4 Fossil fuels and Carbon Dioxide 6


1.4.1 The Club of Rome 6


1.4.2 Climate change 7


1.5 Alternative Energy Sources 9


1.5.1 Introduction 9


1.5.2 Environmental Energy Sources 9


1.5.3 Nuclear power 15


1.5.4 Hydrogen 17


1.6 Biofuels 18


Selected references and suggestions for further reading 19


2 Biofuels in Operation 21
Lionel Clarke


Summary 21


2.1 Fuels for Transport 21


2.2 Future Trends in Fuels Requirements and Technology 24


2.3 Engines and Fuels – Progress vs Inertia 26


2.4 Engine Constraints, Fuel Specifications and Enhanced Performance 28


2.5 Biofuels – Implications and Opportunities 32


2.5.1 Introduction 32


2.5.2 Ethanol 32


2.5.3 Biodiesel 33


2.6 Advanced Biofuels as Alternatives to Ethanol and FAME 37


2.7 Biofuels for Aviation; `Biojet’ 40


2.8 Impact of Future Trends in Engine Design on Retail Biofuels 42


2.9 Conclusion 43


Selected References and Suggestions for Further Reading 43


3 Anaerobic Digestion 45
John Bombardiere and David A. Stafford


Summary 45


3.1 History and Development of Anaerobic Digestion 45


3.1.1 Introduction 45


3.1.2 Mixtures of Micro‐Organisms 46


3.2 Anaerobic Digestion: The Process 47


3.2.1 General Biochemistry 47


3.2.2 Design Types 47


3.2.3 Complete Mix Design 47


3.2.4 Plug Flow Digesters 48


3.2.5 High Dry Solids AD Systems 49


3.2.6 Upflow Anaerobic Sludge Blanket (UASB) 50


3.2.7 Anaerobic Filters 50


3.3 Commercial applications and benefits 51


3.3.1 In the United Kingdom 51


3.3.2 In the USA 51


3.3.3 In Germany 52


3.3.4 Overall Benefits 52


3.4 Ethanol Production Linked with Anaerobic Digestion 53


3.5 Financial and Economic Aspects 54


3.6 UK and US Government Policies and Anaerobic Digestion – an overview 55


3.7 Concluding Comments 56


Selected References and Suggestions for Further Reading 57


4 Plant Cell Wall Polymers 59
Stephen C. Fry


Summary 59


4.1 Nature and Biological Roles of Primary and Secondary Cell Walls 59


4.2 Polysaccharide Composition of Primary and Secondary Cell Walls 60


4.2.1 Typical dicots 60


4.2.2 Differences in Certain Dicots 67


4.2.3 Differences in Monocots 67


4.2.4 Differences in Gymnosperms 68


4.2.5 Differences in Non‐seed Land‐plants 68


4.2.6 Differences in Charophytes 68


4.3 Post‐synthetic Modification of Cell‐wall Polysaccharides 70


4.3.1 C ross‐linking of cell‐wall polysaccharides 70


4.3.2 Hydrolysis of Cell‐wall Polysaccharides 72


4.3.3 `Cutting and Pasting’ (Transglycosylation) of Cell‐wall Polysaccharide Chains 75


4.4 Polysaccharide Biosynthesis 77


4.4.1 General Features 77


4.4.2 At the Plasma Membrane 77


4.4.3 In the Golgi System 78


4.4.4 Delivering the Precursors – sugar Nucleotides 79


4.5 Non‐polysaccharide Components of the Plant Cell Wall 80


4.5.1 Extensins and Other (Glyco)Proteins 80


4.5.2 Polyesters 83


4.5.3 Lignin 84


4.5.4 Silica 84


4.6 Conclusions 85


Acknowledgements 85


Appendix 85


Selected References and Suggestions for Further Reading 85


5 Ethanol Production from Renewable Lignocellulosic Biomass 89
Leah M. Brown, Gary M. Hawkins and Joy Doran–Peterson


Summary 89


5.1 Brief History of Fuel‐Ethanol Production 89


5.2 Ethanol Production from Sugar Cane and Corn 92


5.3 Lignocellulosic Biomass as Feedstocks for Ethanol Production 93


5.3.1 The Organisms 93


5.3.2 Lignocellulosic Biomass 96


5.3.3 Pretreatment of Lignocellulosic Biomass 99


5.3.4 Effect of Inhibitory Compounds on Fermenting Microorganisms 100


5.4 Summary 102


5.5 Examples of Commercial Scale Cellulosic Ethanol Plants 103


5.5.1 Beta Renewables/Biochemtex Commercial Cellulosic Ethanol Plants in Italy, Brazil, USA and Slovak Republic 103


5.5.2 Poet‐DSM `Project Liberty’ – First Commercial Cellulosic Ethanol Plant in the USA 103


5.5.3 Abengoa Hugoton, Kansas commercial plant and MSW to ethanol Demonstration Plant, Salamanca 103


Selected References, Suggestions for Further Reading and Useful Websites 104


6 Fatty Acids, Triacylglycerols and Biodiesel 105
John A. Bryant


Summary 105


6.1 Introduction 105


6.2 Synthesis of Triacylglycerol 107


6.2.1 The Metabolic Pathway 107


6.2.2 Potential for Manipulation 110


6.3 Productivity 111


6.4 Sustainability 114


6.5 More Recently Exploited and Novel Sources of Lipids for Biofuels 114


6.5.1 Higher Plants 114


6.5.2 Algae 115


6.5.3 Prokaryotic Organisms 116


6.6 Concluding Remarks 117


Selected References and Suggestions for Further Reading 117


7 Development of Miscanthus as a Bioenergy Crop 119
John Clifton‐Brown, Jon McCalmont and Astley Hastings


Summary 119


7.1 Introduction 119


7.2 Developing Commercial Interest 122


7.3 Greenhouse Gas Mitigation Potential 127


7.4 Perspectives for `now’ and for the Future 128


Selected References and Suggestions for Further Reading 129


8 Mangrove Palm, Nypa fruticans: `3‐in‐1’ Tree for Integrated Food/Fuel and Eco‐Services 133
C.B. Jamieson, R.D. Lasco and E.T. Rasco


Summary 133


8.1 Introduction: the `Food vs Fuel’ and `ILUC’ Debates 133


8.2 Integrated Food‐Energy Systems (IFES): a Potential Solution 134


8.2.1 Main Features of IFES 134


8.2.2 Baseline Productivity 136


8.3 Land use: the Importance of Forest Ecosystem Services 137


8.4 Sugar Palms: Highly Productive Multi‐Purpose Trees 138


8.5 Nipa (Nipa fruticans): a Mangrove Sugar Palm with Great Promise 140


8.6 Conclusion 141


Selected References and Suggestions for Further Reading 141


9 The Use of Cyanobacteria for Biofuel Production 143
David J. Lea‐Smith and Christopher J. Howe


Summary 143


9.1 Essential Aspects of Cyanobacterial Biology 143


9.1.1 General Features 143


9.1.2 Photosynthesis and Carbon Dioxide Fixation 144


9.1.3 Nitrogen Fixation 146


9.2 Commercial Products Currently Derived from Cyanobacteria 146


9.3 Cyanobacteria Culture 147


9.4 Cyanobacterial Genomes and Genetic Modification for Biofuel Production 148


9.5 Industrial Production of Biofuels from Cyanobacteria 152


9.6 Conclusion 154


Selected References and Suggestions for Further Reading 154


10 Third‐Generation Biofuels from the Microalga, Botryococcus braunii 157
Charlotte Cook, Chappandra Dayananda, Richard K. Tennant and John Love


Summary 157


10.1 Botryococcus braunii 157


10.2 Microbial Interactions 160


10.3 Botryococcus braunii as a Production Platform for Biofuels or


Chemicals 161


10.3.1 Hydrocarbons, Lipids and Sugars 161


10.3.2 Controlling and Enhancing Productivity 163


10.3.3 Alternative Culture Systems 165


10.3.4 Harvesting Botryococcus Biomass and Hydrocarbons 166


10.3.5 Processing Botryococcus into an Alternative Fuel 166


10.4 Improving Botryococcus 167


10.5 Future Prospects and Conclusion 169


Selected References and Suggestions of Further Reading 170


11 Strain Selection Strategies for Improvement of Algal Biofuel Feedstocks 173
Leyla T. Hathwaik and John C. Cushman


Summary 173


11.1 Introduction 173


11.2 Lipids in Microalgae 174


11.3 Starch in Microalgae 175


11.4 Metabolic Interconnection Between Lipid and Starch Biosynthesis 176


11.5 Strategies for the Selection of Microalgae Strains with Enhanced Biofuel Feedstock Traits 177


11.5.1 Manipulation of Growth Conditions 177


11.5.2 Genetic Mutagenesis 177


11.5.3 F low Cytometry 178


11.5.4 Fluorescence‐Activated Cell Sorting 181


11.5.5 Buoyant Density Centrifugation 183


11.6 Conclusions 185


Acknowledgements 185


Selected References and Suggestions for Further Reading 185


12 Algal Cultivation Technologies 191
Alessandro Marco Lizzul and Michael J. Allen


Summary 191


12.1 Introduction 191


12.2 Lighting 192


12.3 Mixing 194


12.4 Control Systems and Construction Materials 196


12.5 Algal Production Systems at Laboratory Scale 197


12.6 Algal Production in Open Systems 198


12.6.1 Pond‐Based Systems 198


12.6.2 Membrane Reactors 200


12.7 Algal production in Closed Systems 201


12.7.1 Introduction 201


12.7.2 Plate or Panel Based Systems 201


12.7.3 Horizontal Tubular Systems 203


12.7.4 Bubble Columns 205


12.7.5 Airlift Reactors 207


12.8 Concluding Comments 209


Selected References and Suggestions for Further Reading 209


13 Biofuels from Macroalgal Biomass 213
Jessica Adams


Summary 213


13.1 Macroalgal resources in the UK 213


13.2 Suitability of macroalgae for biofuel production 214


13.3 Biofuels from Macroalgae 217


13.3.1 Introduction 217


13.3.2 Ethanol from laminarin, mannitol and alginate 217


13.3.3 Ethanol from cellulose 219


13.3.4 Butanol 220


13.3.5 Anaerobic digestion 221


13.3.6 Thermochemical conversions 223


13.4 Future prospects 223


13.5 Conclusion 224


Acknowledgements 224


Selected References and Suggestions for Further Reading 224


14 Lipid‐based Biofuels from Oleaginous Microbes 227
Lisa A. Sargeant, Rhodri W. Jenkins and Christopher J. Chuck


Summary 227


14.1 Introduction 227


14.2 Microalgae 229


14.3 Oleaginous Yeasts 231


14.4 Feedstocks for Heterotrophic Microbial Cultivation 231


14.5 The Biochemical Process of Lipid Accumulation in Oleaginous Yeast 232


14.6 Lipid Profile of Oleaginous Microbes 236


14.7 Lipid Extraction and Processing 237


14.8 Concluding Comments 237


Selected References and Suggestions for Further Reading 239


15 Engineering Microbial Metabolism for Biofuel Production 241
Thomas P. Howard


Summary 241


15.1 Introduction 241


15.2 Designer Biofuels 242


15.2.1 Introduction 242


15.2.2 Isoprenoid‐Derived Biofuels 243


15.2.3 Higher Alcohols 245


15.2.4 Fatty Acid‐Derived Biofuels 247


15.2.5 Petroleum Replica Hydrocarbons 249


15.3 Towards Industrialisation 251


15.3.1 Introduction 251


15.3.2 Bioconsolidation 251


15.3.3 Molecular and Cellular Redesign 255


15.3.4 Biofuel Pumps 256


15.3.5 Synthetic Biology and Systems Engineering 257


15.4 Conclusion 258


Selected References and Suggestions for Further Reading 259


16 The Sustainability of Biofuels 261
J.M. Lynch


Summary 261


16.1 Introduction 261


16.2 Bioenergy policies 262


16.3 Economics of bioenergy markets 263


16.4 Environmental issues 264


16.5 Life Cycle Assessment 266


16.5.1 General features 266


16.5.2 OECD Copenhagen workshop, 2008 267


16.6 Conclusions 270


Selected references and suggestions for further reading 271


17 Biofuels and Bioenergy – Ethical Aspects 273
John A. Bryant and Steve Hughes


Summary 273


17.1 Introduction to ethics 273


17.1.1 How do we Make Ethical or Moral Decisions? 273


17.1.2 Environmental ethics 275


17.2 Biofuels and Bioenergy – Ethical Background 276


17.3 The Key Ethical Issues 276


17.3.1 Biofuel production and the growth of Food Crops 276


17.3.2 Is growth of Biofuel Crops Sustainable? 278


17.3.3 Biofuel Production, Land Allocation and Human Rights 279


17.4 Concluding comment 283


Selected references and suggestions for further reading 283


18 Postscript 285
John Love and John A. Bryant


Selected References and Suggestions for Further Reading 287


Index 289