Biofuels and Bioenergy

Biofuels and Bioenergy

Edited by John Love and John A. BryantBiosciences, College of Life and Environmental Sciences, University of Exeter, UK

This edition first published 2017 © 2017 by John Wiley and Sons Ltd

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Names: Love, John and Bryant, John A.Title: Biofuels and bioenergy / [edited by] John Love and John A. Bryant.Description: Chichester, West Sussex : John Wiley & Sons, Inc., 2017. |

Includes bibliographical references and index.Identifiers: LCCN 2016059291 (print) | LCCN 2017000214 (ebook) | ISBN 9781118350560 (cloth) |

ISBN 9781118350546 (pdf) | ISBN 9781118350539 (epub)Subjects: LCSH: Biomass energy. | Algal biofuels.Classification: LCC TP339 .B5394 2017 (print) | LCC TP339 (ebook) | DDC 662/.88–dc23LC record available at https://lccn.loc.gov/2016059291

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Cover image: Courtesy of John LoveAnaerobic Digestion of food or agricultural waste and sewage is a tried and tested method for producing renewable methane, or “Biogas”, which can either be used directly or to make electricity. The residues from the process are then used as fertiliser to grow crops. The cover image is of an anaerobic digestor plant at Bygrave near Baldock, England, that is owned and run by Biogen. Every year, the plant transforms 45,000 tonnes of food waste into enough electricity to power about 4,500 homes.

Cover design by Wiley

Set in 10/12pt Warnock by SPi Global, Pondicherry, India

10 9 8 7 6 5 4 3 2 1

v

Contents

List of Contributors xiiiPreface xvList of Abbreviations xix

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

Summary 11.1 Introduction 11.2 Some history 11.2.1 Wood and charcoal 11.2.2 Dung as fuel 21.2.3 Oils and fats 21.2.4 Peat 31.3 fossil fuels 41.3.1 coal 41.3.2 Petroleum Oil 51.3.3 Natural gas 61.4 fossil fuels and carbon Dioxide 61.4.1 The club of Rome 61.4.2 climate change 71.5 Alternative Energy Sources 91.5.1 Introduction 91.5.2 Environmental Energy Sources 91.5.3 Nuclear Power 151.5.4 hydrogen 171.6 Biofuels 18 Selected References and Suggestions for further Reading 19

2 Biofuels in Operation 21Lionel Clarke

Summary 212.1 fuels for Transport 212.2 future Trends in fuels Requirements and Technology 242.3 Engines and fuels – Progress vs Inertia 262.4 Engine constraints, fuel Specifications and Enhanced Performance 28

Contentsvi

2.5 Biofuels – Implications and Opportunities 322.5.1 Introduction 322.5.2 Ethanol 322.5.3 Biodiesel 332.6 Advanced Biofuels as Alternatives to Ethanol and fAME 372.7 Biofuels for Aviation; ‘Biojet’ 402.8 Impact of future Trends in Engine Design on Retail Biofuels 422.9 conclusion 43 Selected References and Suggestions for further Reading 43

3 Anaerobic Digestion 45John Bombardiere and David A. Stafford

Summary 453.1 history and Development of Anaerobic Digestion 453.1.1 Introduction 453.1.2 Mixtures of Micro‐Organisms 463.2 Anaerobic Digestion: The Process 473.2.1 general Biochemistry 473.2.2 Design Types 473.2.3 complete Mix Design 473.2.4 Plug flow Digesters 483.2.5 high Dry Solids AD Systems 493.2.6 Upflow Anaerobic Sludge Blanket (UASB) 503.2.7 Anaerobic filters 503.3 commercial Applications and Benefits 513.3.1 In the United Kingdom 513.3.2 In the USA 513.3.3 In germany 523.3.4 Overall Benefits 523.4 Ethanol Production Linked with Anaerobic Digestion 533.5 financial and Economic Aspects 543.6 UK and US government Policies and Anaerobic

Digestion – An Overview 553.7 concluding comments 56 Selected References and Suggestions for further Reading 57

4 Plant Cell Wall Polymers 59Stephen C. Fry

Summary 594.1 Nature and Biological Roles of Primary and Secondary cell Walls 594.2 Polysaccharide composition of Primary and Secondary cell Walls 604.2.1 Typical Dicots 604.2.2 Differences in certain Dicots 674.2.3 Differences in Monocots 674.2.4 Differences in gymnosperms 684.2.5 Differences in Non‐seed Land‐plants 684.2.6 Differences in charophytes 68

Contents vii

4.3 Post‐synthetic Modification of cell‐wall Polysaccharides 704.3.1 cross‐linking of cell‐wall Polysaccharides 704.3.2 hydrolysis of cell‐wall Polysaccharides 724.3.3 ‘cutting and Pasting’ (Transglycosylation) of cell‐wall Polysaccharide

chains 754.4 Polysaccharide Biosynthesis 774.4.1 general features 774.4.2 At the Plasma Membrane 774.4.3 In the golgi System 784.4.4 Delivering the Precursors – Sugar Nucleotides 794.5 Non‐polysaccharide components of the Plant cell Wall 804.5.1 Extensins and Other (glyco)Proteins 804.5.2 Polyesters 834.5.3 Lignin 844.5.4 Silica 844.6 conclusions 85 Acknowledgements 85 Appendix 85 Selected References and Suggestions for further Reading 85

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

Summary 895.1 Brief history of fuel‐Ethanol Production 895.2 Ethanol Production from Sugar cane and corn 925.3 Lignocellulosic Biomass as feedstocks for Ethanol Production 935.3.1 The Organisms 935.3.2 Lignocellulosic Biomass 965.3.3 Pretreatment of Lignocellulosic Biomass 995.3.4 Effect of Inhibitory compounds on fermenting Microorganisms 1005.4 Summary 1025.5 Examples of commercial Scale cellulosic Ethanol Plants 1035.5.1 Beta Renewables/Biochemtex commercial cellulosic Ethanol Plants in Italy,

Brazil, USA and Slovak Republic 1035.5.2 Poet‐DSM ‘Project Liberty’ – first commercial cellulosic Ethanol Plant

in the USA 1035.5.3 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 105John A. Bryant

Summary 1056.1 Introduction 1056.2 Synthesis of Triacylglycerol 1076.2.1 The Metabolic Pathway 1076.2.2 Potential for Manipulation 110

Contentsviii

6.3 Productivity 1116.4 Sustainability 1146.5 More Recently Exploited and Novel Sources of Lipids for Biofuels 1146.5.1 higher Plants 1146.5.2 Algae 1156.5.3 Prokaryotic Organisms 1166.6 concluding Remarks 117 Selected References and Suggestions for further Reading 117

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

Summary 1197.1 Introduction 1197.2 Developing commercial Interest 1227.3 greenhouse gas Mitigation Potential 1277.4 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 133C.B. Jamieson, R.D. Lasco and E.T. Rasco

Summary 1338.1 Introduction: The ‘food vs fuel’ and ‘ILUc’ Debates 1338.2 Integrated food‐Energy Systems (IfES): A Potential Solution 1348.2.1 Main features of IfES 1348.2.2 Baseline Productivity 1368.3 Land use: The Importance of forest Ecosystem Services 1378.4 Sugar Palms: highly Productive Multi‐Purpose Trees 1388.5 Nipa (Nipa fruticans): A Mangrove Sugar Palm with great Promise 1408.6 conclusion 141 Selected References and Suggestions for further Reading 141

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

Summary 1439.1 Essential Aspects of cyanobacterial Biology 1439.1.1 general features 1439.1.2 Photosynthesis and carbon Dioxide fixation 1449.1.3 Nitrogen fixation 1469.2 commercial Products currently Derived from cyanobacteria 1469.3 cyanobacteria culture 1479.4 cyanobacterial genomes and genetic Modification for Biofuel

Production 1489.5 Industrial Production of Biofuels from cyanobacteria 1529.6 conclusion 154 Selected References and Suggestions for further Reading 154

Contents ix

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

Summary 15710.1 Botryococcus braunii 15710.2 Microbial Interactions 16010.3 Botryococcus braunii as a Production Platform for Biofuels or

chemicals 16110.3.1 hydrocarbons, Lipids and Sugars 16110.3.2 controlling and Enhancing Productivity 16310.3.3 Alternative culture Systems 16510.3.4 harvesting Botryococcus Biomass and hydrocarbons 16610.3.5 Processing Botryococcus into an Alternative fuel 16610.4 Improving Botryococcus 16710.5 future Prospects and conclusion 169 Selected References and Suggestions of further Reading 170

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

Summary 17311.1 Introduction 17311.2 Lipids in Microalgae 17411.3 Starch in Microalgae 17511.4 Metabolic Interconnection Between Lipid and Starch Biosynthesis 17611.5 Strategies for the Selection of Microalgae Strains with Enhanced Biofuel

feedstock Traits 17711.5.1 Manipulation of growth conditions 17711.5.2 genetic Mutagenesis 17711.5.3 flow cytometry 17811.5.4 fluorescence‐Activated cell Sorting 18111.5.5 Buoyant Density centrifugation 18311.6 conclusions 185 Acknowledgements 185 Selected References and Suggestions for further Reading 185

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

Summary 19112.1 Introduction 19112.2 Lighting 19212.3 Mixing 19412.4 control Systems and construction Materials 19612.5 Algal Production Systems at Laboratory Scale 19712.6 Algal Production in Open Systems 19812.6.1 Pond‐Based Systems 19812.6.2 Membrane Reactors 200

Contentsx

12.7 Algal production in closed Systems 20112.7.1 Introduction 20112.7.2 Plate or Panel Based Systems 20112.7.3 horizontal Tubular Systems 20312.7.4 Bubble columns 20512.7.5 Airlift Reactors 20712.8 concluding comments 209 Selected References and Suggestions for further Reading 209

13 Biofuels from Macroalgal Biomass 213Jessica Adams

Summary 21313.1 Macroalgal Resources in the UK 21313.2 Suitability of Macroalgae for Biofuel Production 21413.3 Biofuels from Macroalgae 21713.3.1 Introduction 21713.3.2 Ethanol from Laminarin, Mannitol and Alginate 21713.3.3 Ethanol from cellulose 21913.3.4 Butanol 22013.3.5 Anaerobic Digestion 22113.3.6 Thermochemical conversions 22313.4 future Prospects 22313.5 conclusion 224 Acknowledgements 224 Selected References and Suggestions for further Reading 224

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

Summary 22714.1 Introduction 22714.2 Microalgae 22914.3 Oleaginous Yeasts 23114.4 feedstocks for heterotrophic Microbial cultivation 23114.5 The Biochemical Process of Lipid Accumulation in Oleaginous Yeast 23214.6 Lipid Profile of Oleaginous Microbes 23614.7 Lipid Extraction and Processing 23714.8 concluding comments 237 Selected References and Suggestions for further Reading 239

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

Summary 24115.1 Introduction 24115.2 Designer Biofuels 24215.2.1 Introduction 24215.2.2 Isoprenoid‐Derived Biofuels 243

Contents xi

15.2.3 higher Alcohols 24515.2.4 fatty Acid‐Derived Biofuels 24715.2.5 Petroleum Replica hydrocarbons 24915.3 Towards Industrialisation 25115.3.1 Introduction 25115.3.2 Bioconsolidation 25115.3.3 Molecular and cellular Redesign 25515.3.4 Biofuel Pumps 25615.3.5 Synthetic Biology and Systems Engineering 25715.4 conclusion 258 Selected References and Suggestions for further Reading 259

16 The Sustainability of Biofuels 261J.M. Lynch

Summary 26116.1 Introduction 26116.2 Bioenergy Policies 26216.3 Economics of Bioenergy Markets 26316.4 Environmental Issues 26416.5 Life cycle Assessment 26616.5.1 general features 26616.5.2 OEcD copenhagen Workshop, 2008 26716.6 conclusions 270 Selected References and Suggestions for further Reading 271

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

Summary 27317.1 Introduction to Ethics 27317.1.1 how Do We Make Ethical or Moral Decisions? 27317.1.2 Environmental Ethics 27517.2 Biofuels and Bioenergy – Ethical Background 27617.3 The Key Ethical Issues 27617.3.1 Biofuel Production and the growth of food crops 27617.3.2 Is growth of Biofuel crops Sustainable? 27817.3.3 Biofuel Production, Land Allocation and human Rights 27917.4 concluding comment 283 Selected References and Suggestions for further Reading 283

18 Postscript 285John Love and John A. Bryant

Selected References and Suggestions for further Reading 287

Index 289

xiii

Jessica AdamsUniversity of Aberystwyth, Wales, UK

Michael J. AllenPlymouth Marine Laboratory, Plymouth, UK

John BombardiereWest Virginia State University, USA

Leah M. BrownUniversity of Georgia, Athens, USA

John A. BryantUniversity of Exeter, Exeter, UK

Christopher J. ChuckUniversity of Bath, Bath, UK

Lionel ClarkeBionerG Ltd, Chester, UK

John Clifton‐BrownUniversity of Aberystwyth, Wales, UK

Charlotte CookUniversity of Exeter, Exeter, UK

John C. CushmanUniversity of Nevada, Reno, USA

Chappandra DayanandaCentral Food Technological Research Institute, Mysore, India

Joy Doran‐PetersonUniversity of Georgia, Athens, USA

Stephen C. FryUniversity of Edinburgh, Edinburgh, UK

Astley HastingsUniversity of Aberdeen, Scotland, UK

Leyla T. HathwaikUniversity of Nevada, Reno, USA

Gary M. HawkinsUniversity of Georgia, Athens, USA

Thomas P. HowardUniversity of Newcastle, Newcastle-on-Tyne, UK

Christopher J. HoweUniversity of Cambridge, Cambridge, UK

Steve HughesUniversity of Exeter, Exeter, UK

C.B. JamiesonWorld Agroforestry Centre, Laguna, Philippines andNext Generation, Hertfordshire, UK

Rhodri W. JenkinsUniversity of Bath, Bath, UK

R.D. LascoWorld Agroforestry Centre, Laguna, Philippines

List of Contributors

List of Contributorsxiv

David J. Lea‐SmithUniversity of Cambridge, Cambridge, UK

Alessandro Marco LizzulUniversity College London, London, UK

John LoveUniversity of Exeter, Exeter, UK

J.M. LynchUniversity of Surrey, Guildford, UK

Jon McCalmontUniversity of Aberystwyth, Wales, UK

E.T. RascoPhilRice, Munoz, Philippines

Lisa A. SargeantUniversity of Bath, Bath, UK

David A. StaffordEnviro‐Control Ltd., Devon, UK

Richard K. TennantUniversity of Exeter, Exeter, UK

xv

A century ago, petroleum – what we call oil – was just an obscure commodity; today it is almost as vital to human existence as water.

James Buchan, Political commentator and author

The use of vegetable oils for engine fuels may seem insignificant today. But such oils may become in course of time as important as petroleum and the coal tar products of the present time.

Rudolf Diesel, engineer and inventor of the compression engine (quotation dates from 1912)

Most people have difficulty coming to grips with the sheer enormity of energy consumption.

Rex Tillerson, Civil engineer, businessman and President/CEO of the Exxon‐Mobil Corporation

We have to rethink our whole energy approach, which is hard to do because we’re so dependent on oil, not just for fuel but also plastic … We have to think quite carefully about using oil and its derivatives, because it’s not going to be around forever.

Margaret Atwood, Author, literary critic and environmental activist

We can no longer allow America’s dependence on foreign oil to compromise our energy security. Instead, we must invest in inventing new ways to power our cars and our economy. I’ll put my faith in American science and ingenuity any day before I depend on Saudi Arabia.

Senator John Kerry, US Secretary of State, 2013–2016

There is an urgent need to stop subsidizing the fossil fuel industry, dramatically reduce wasted energy, and significantly shift our power supplies from oil, coal, and natural gas to wind, solar, geothermal, and other renewable energy sources.

Bill McKibben, Author, educator and environmental activist

These quotations provide a nice series of snapshots. The world is energy‐hungry and increasingly so. The need for fuels for transport makes up a large proportion of that hunger. That need is largely met by petroleum (literally ‘rock‐oil’), 70% of which is used for transport by road, air or sea, but there are issues related to its continued use and availability (even if concerns about ‘peak oil’ – the moment when global oil production reaches its maximum – have declined somewhat). There are concerns that some developed countries’ need for oil may make them economic or moral hostages to countries that are

Preface

Prefacexvi

oil producers. And above all is the realisation that burning fossil fuels (principally coal, natural gas and oil) is the major contributor to anthropogenic climate change. There is thus a drive to develop renewable sources of energy, sources of energy that do not involve burning fossil fuels. And we have to say, as is evident from Chapter 1, there has been very good progress in generation of electricity via environmental energy sources. Electricity can of course be used to power some forms of transport. but it still glaringly obvious that transport is very dependent on oil (and to a lesser extent, coal and gas), and will continue to be dependent on liquid fuels well into the future. So we come to this book, which deals with current areas of research aimed at finding ways of using renew-able biological resources to provide fuels mainly for transport, research which becomes ever more urgent as the reality of climate change becomes more apparent.

Biofuels, therefore, should be viewed in the context of sustainability, either as alterna-tives to reduce petroleum use during the transition to other forms of transport, energy or primary materials, or as a way to mitigate climate change. The use of petroleum distillate in mass transport did not happen overnight (indeed petrol was once consid-ered a waste product of oil refining); likewise, biofuels are at the very early stages of development. Biofuels research is intense, with new options being imagined and solutions being proposed almost weekly. Every new technology explores a previously unimagined design landscape. The issue with biofuels is that technical developments are heavily constrained by existing infrastructure, land use and global commerce in commodities. As yet, we cannot pick the future biofuel ‘winners’, but any biofuel solution (and there may be several) must be responsive to a number of criteria, including cost, technical feasibility, efficiency, reliability, sustainability and, arguably most difficult of all, our lifestyle expectations.

We are bound to say that the book has been a long time coming. It is actually several years since a conversation in an Oxford coffee shop between JAB and Rachel Wade of Wiley‐Blackwell led to the idea of an edited text on Biofuels. It took a long time to recruit authors and even then, other factors outside the control of editors and publisher, led to further delays and loss of some of the planned and contracted chapters. Against this background, we are especially grateful to those authors who have remained with the project and provided the excellent and interesting range of chapters presented here. A number of them have been remarkably patient as they waited for news of further progress after submitting their chapters. We are also grateful to colleagues who have given us their time in discussion and/or provided diagrams and figures for us to use. JAB expresses special thanks to Dr David Stafford of Enviro‐Control Ltd, Professor Jim Lynch of the University of Surrey and Professor Steve Hughes of the University of Exeter for their long‐term friendship, support and readiness to share their knowledge and expertise; also to environmental engineer, Rachel Oates of the Lee Abbey Community, Devon, for her knowledgeable enthusiasm and readiness to talk about environmental energy sources, especially ‘micro‐hydro’ (see Chapter 1). JL is especially indebted to Professor Rob Lee of Royal Dutch Shell, his ‘partner in slime’ for the past 15 years and to Drs Mike Goosey and Jeremy Shears, both directors of Shell Biodomain, for their positive and supportive vision of open innovation between academia and industry to solve global problems. Heartfelt thanks also to all of the current and past members of the Exeter Microbial Biofuels Group for their talent, commitment, profes-sionalism and humour, to our numerous collaborators in academia and in industry, and to the BBSRC for supporting our research. Our programme would not be possible without

Preface xvii

the direct support of the University of Exeter. JL is personally grateful to our Vice Chancellor Professor Sir Steve Smith and to our Deputy Vice‐Chancellor for research, Professor Nick Talbot, FRS (formerly his head of department) for their genuine and sustained interest, and to his all colleagues in professional services, notably Linda Peka and Caroline Hampson, for their immeasurable patience in underpinning our research.

Finally, we want to say a big ‘Thank You’ for the patience of our publishers at Wiley‐Blackwell and especially those closely involved with this book, Rachel Wade at Oxford who helped to initiate the project, Fiona Seymour at Chichester who was for a long time ‘our’ editor, Audrie Tan at Singapore who took over from Fiona as the last few chapters came in and Vinodhini Mathiyalagan together with Shummy Metilda who supervised the book’s production. It would have been so easy for these individuals and for Wiley‐Blackwell themselves to abandon the book as we sought yet another re‐scheduling. We are very grateful that they stuck with us.

John LoveJohn A. Bryant

Exeter, August 2015

xix

AAT ATP‐ADP translocaseACC Acetyl‐CoA carboxylaseACL ATP‐citrate lyaseAck Acetate kinaseACP Acyl carrier proteinACS Acyl‐CoA synthetaseAD Anaerobic digestionADH Alcohol dehydrogenaseAdhE2 Butaraldehyde/butanol dehydrogenaseAFEX Ammonia fibre expansionADO Aldehyde decarbonylaseALR Airlift reactorAS ATP synthaseATJ Alcohol to jetAtoAD Acetoacetyl‐CoA transferaseATP‐CL ATP‐citrate lyaseB100 100% biodieselBBSRC Biotechnology and Biological Sciences Research Councilbbl BarrelsBcd Butyrl‐CoA dehydrogenaseBCKD Branched chain ketoacid dehydrogenseBDC Buoyant density centrifugationBDGC Buoyant density gradient centrifugationBIS Bisbolene synthaseBOD Biological oxygen demandBTL Bio‐to‐liquidsCAR Carboxylic acid reductaseCcr Cronotyl‐CoA reductaseCCX Chicago Climate ExchangeCFPP Cold Filter Plugging PointCH Catalytic hydrothermolysisCI Cetane indexC/N Carbon to nitrogen ratioCN Cetane numberCP Cloud point

List of Abbreviations

List of Abbreviationsxx

CRP Cyclic AMP (cAMP) receptor proteinCSL Cellulose synthase‐likeCtfAB Coenzyme A transferase, A and B subunitsDAG DiacylglycerolDAGAT Diacyglycerol acyltransferaseDDG Dried distillers grainDDGS Dried distillers grains with solublesDEFRA Department of Food, Rural Affairs and AgricultureDIC Dicarboxylate carrierDM Dry matterDMAPP Dimethylallyll diphosphateDMSO Dimethyl sulfoxideDoE Department of EnergyDPF Diesel particulate filterDSHC Direct sugar to hydrocarbonsE85 85% ethanolEBI Energy Biosciences InstituteECM Extracellular matrixEJ ExajoulesELA Extremely low acidEMP Embden‐Meyerhof‐ParnasEPA Environmental Protection AgencyEPIC Environmental Policy Integrated ClimateER Endoplasmic reticulumEU European UnionFA Fatty acidFAAE Fatty acid alkyl estersFACS Fluorescence activated cell sortingfadD Fatty acyl‐CoA synthetaseFAEE Fatty‐acid ethyl esterFAME Fatty acid methyl esterFAO Food and Energy OrganisationFAR Fatty acid reductaseFAS Fatty‐acid synthaseFCM Flow cytometryFPP Farneseyl pyrophosphateFS Farnesene synthaseG‐3‐P Glycerol‐3‐phosphateGAT G‐3‐P acyltransferaseGC Gas chromatographyGDSL Gly‐Asp‐Ser‐LeuGGPP Geranylgeranyl pyrophosphateGHG Greenhouse gasesGIS Geographic Information SystemGM Genetically modifiedGPP Geranyl pyrophosphateGTL Gas‐to‐liquids

List of Abbreviations xxi

GTME Global transcriptional machinery engineeringGW GigawattsHbd 3‐hydroxybutyrl‐CoA dehydrogenaseHCCI Homogenous charge compression ignitionHDCJ Hydrotreated depolymerised cellulosic jetHEFA Hydroprocessed esters and fatty acidsHGA HomogalacturonanHMF HydroxymethylfurfuralHRAP High rate algal pondHT HydrotreatmentIFES Integrated food‐energy systemsIFQC International Fuel Quality CentreiGEM Internationally Genetically Engineered MachinesLA Lysophosphatic acidILUC Indirect Land Use Change/integrated land use changeIOU Investor‐owned utilitiesIPP Isopentenyl diphosphateIPPC Inter‐Governmental Panel on Climate ChangeispS Isoprene synthaseKDC Ketoacid decarboxylasekW KilowattsLB Lipid bodiesLCA Life cycle analysis/Life Cycle AssessmentLdh L‐lactate dehydrogenaseLED Light emitting diodeLNG Liquefied Natural GasLNS Light natural sandwichlpa Lysophosphatidic acidLPAAT Lysophosphatidic acid acyltransferaseLS Limonene synthaseLUC Land Use ChangeMAG 2‐monoacylglycerolMDH Malate dehydrogenaseME1 Malic enzymeMEP 2‐C‐methyl‐D‐erythritol‐4‐phosphateMEV MevalonateMIT Massachusetts Institute of TechnologyMLG Mixed‐linkage glucanMSW Municipal solid wasteMW MegawattsMXE MLG:xyloglucan endotransglucosylaseNDP An N‐galacturonoyl amideNGO Non‐Governmental OrganisationNMR Nuclear magnetic resonanceNOx Nitrogen oxidesOECD Organisation for Economic Cooperation and DevelopmentOEM Optical Emission Spectroscopy

List of Abbreviationsxxii

OPEC Organization of the Petroleum Exporting CountriesPA Phosphatidic acidPAP Phosphatic acid phosphohydrolasePBR PhotobioreactorPC Pyruvate carboxylasePdc Thiamine pyrophosphatePDH Pyruvate dehydrogenasePHB PolyhydroxybutyratePME Pectin methylesterasePP Pour pointPPi Pyrophosphateppm Parts per millionPPP Pentose phosphate pathwayPS Pinene synthasePT Pyruvate transporterPta Phosphate acetyltransferasePV PhotovoltaicPVC Polyvinyl chloridePVP PolyvinylpyrrolidoneQTL Quantitative trait locus/lociR&D Research and DevelopmentREACH Registration, Evaluation and Authorisation of ChemicalsREC Renewable Energy CertificateRED Renewable Energy DirectiveREDD + Reduction of Emissions Due to Deforestation and Forest DegradationRFS Renewable Fuel StandardsRME Rape‐seed methyl esterRG RhamnogalacturonanRPS Renewables Portfolio StandardRVP Reid Vapour PressureS‐AM S‐adenosyl methonine transferaseSI Spark‐ignitionSCO Single‐cell oilSOC Soil organic carbonSSL Squalene synthase‐likeTAG TriacylglycerolTBA Tertiary butanolTCA Tricarboxylic acidTCL Thermo‐chemical liquefactionTe ThioesteraseTFA Trifluoroacetic acidThl ThiolaseTIC Tricarboxylate carrierTPP Thiamine pyrophosphateTW TerawattsULS Ultra‐low sulphurUSDA US Department of Agriculture

List of Abbreviations xxiii

USDoE US Department of EnergyUSPS US Postal ServiceUV Ultra‐violetWRAP Waste Resources Action ProgrammeXEG Xyloglucan endo‐glucanaseXET Xyloglucan endotransglucosylaseXTH Xyloglucan endotransglucosylase/hydrolase

Biofuels and Bioenergy, First Edition. Edited by John Love and John A. Bryant. © 2017 John Wiley & Sons Ltd. Published 2017 by John Wiley & Sons Ltd.

1

1

Summary

This chapter looks at the history of the use of fossil and non‐fossil fuels and of environmental energy sources from the earliest phases of human society right up to the present day. Factors, especially climate change, which affect the use of particular fuels are discussed. The chapter ends with an overview of biofuels, thus setting the scene for the rest of the book.

1.1 Introduction

The earliest recorded use of the word biofuel was in 1970 when it was defined as ‘a fuel (such as wood or ethanol) composed of or produced from biological raw materials.’ Use of the term gradually became more frequent but it is only in last 15 years or so that it has entered into everyday speech. The definition has also widened: the Oxford Dictionary On‐line now simply states ‘a fuel derived immediately from living matter’. This clearly covers much more than wood and ethanol; the range will be apparent from the chapters in this book. The purpose of this chapter is to provide the context for, and to discuss the reasons behind, this increased interest in biofuels. It is an unfolding story of human ingenuity and inventiveness in the search for sources of light and heat and of energy for industry, transport, commerce and domestic appliances. It is a fascinating story that sets the scene for the rest of the book.

1.2 Some History

1.2.1 Wood and Charcoal

Although the first recorded use of the word was relatively recent, the use of biofuels actually goes back much further. Biological materials have been used as energy

Biofuels: The Back StoryJohn A. Bryant and John Love

College of Life and Environmental Sciences, University of Exeter, Exeter, UK

Biofuels and Bioenergy2

sources throughout human existence; indeed it is likely that the Neanderthals had discovered fire and the use of wood as a fuel. On a small local scale, burning of wood as a fuel may be regarded as having a very small ‘ecological footprint’, especially since, reflecting our modern concerns, it releases only recently fixed CO2 into the atmosphere.

Pyrolysis of wood in the absence of air produces charcoal, a form of carbon that burns at a higher temperature than wood and can thus be used in metal smelting. The use of charcoal as a fuel dates back at least 6,000 years (and probably longer). Initially it was confined to Egypt and what is now known as the Middle East. Its use soon spread across Europe so that by the Middle Ages, charcoal production was very widespread and resulted in extensive deforestation over large areas. It thus had an ecological/environ-mental impact that today we would regard at least as undesirable.

With the invention of a method for making coke from coal (i.e. a fossil fuel), charcoal production declined dramatically, especially from 1900 onwards (although one of us can remember seeing charcoal burners in woods in Surrey in the middle years of the 20th century). Today the use of charcoal as a fuel1 in developed countries is largely confined to domestic barbecues. However, across the world, wood and charcoal are still the mostly widely used fuels. This includes the use of wood‐burning stoves in people’s homes and wood‐burning power stations, often regarded as environmentally friendly because, as noted before, it is recently fixed CO2 that is released. This CO2 release may be further mitigated by the planting of replacement trees in managed for-estry systems. However, there is no universal agreement on this; some think that grow-ing wood just for burning is not wise when the wood could have so many other uses2. Furthermore, in many parts of the world where emissions are less stringently con-trolled, burning of wood often causes serious smoke pollution and damaging effects on human health.

1.2.2 Dung as Fuel

Evidence for use of dried animal dung as fuel dates back about 9,000 years to Neolithic communities in which cattle, sheep, goats and pigs had been domesticated. It is still used today in many less‐developed countries. There is also evidence for use by Native Americans of dung from wild bison in the prairies where wood fuel was very scarce or non‐existent. There is undoubtedly today support for increased use of dung as fuel, both in what we might call traditional or semi‐traditional methods and by anaerobic digestion (see Chapter 3).

1.2.3 Oils and Fats

The use of natural oils for lighting dates back to about 15,000 years. Most ancient oil lamps ran on plant oils. Thus the lamps referred to in the Old and New Testaments of the Bible and in the Qur’an were fuelled with olive oil. Both plant and animal oils were also used for lighting in ancient Egypt, dating back to about 3000 bc: rushlights, precursors to candles, were made by dipping rolled‐up papyrus into oil or into melted

1 Powdered charcoal has several non-fuel uses, including absorption of gases and purification of liquids.2 http://www.usewoodwisely.co.uk/

Biofuels: The Back Story 3

beeswax or melted animal fat. The Romans are generally credited with invention of the true candle containing a wick that ran through the length of a cylinder of bees’ wax (other solid animal fats may also be used).

Another animal‐based biofuel is whale oil, which was used for lighting from the 17th until the second half of the 19th century, when it was finally displaced by kerosene and by coal gas (see also Sections 1.3.2 and 1.3.3). It was noted that ‘sperm oil’ (from the head of the sperm whale) gave a much cleaner and less odoriferous flame than whale blubber oil and this was one of the factors that led to intensive hunting of sperm whales in the 18th and 19th centuries. Thus, in the period between 1770 and 1775, the north-eastern United States produced about 7.16 million litres of sperm oil per year. At least 6,400 sperm whales would have been killed annually to supply this amount of oil. Hunting at this intensity continued until the second half of the 19th century and of course was not confined to US‐based whaling fleets. It is estimated that the world popu-lation of sperm whales declined by about 235,000 in the 18th century alone and it seems very likely that they would have been hunted to extinction3 had petroleum oil and oil‐based products not displaced sperm oil as fuels of choice.

1.2.4 Peat

The last traditional biological fuel we wish to consider is peat. This occurs in the wetter areas of the world, covering between 2% and 3% of the global land area, and consists of compressed and partly rotted remains of plants, especially Sphagnum moss. It may thus be regarded as being part way to forming lignite, a form of coal. Peat is cut from the bog in slices, known in Ireland and Scotland as turves (singular turf), which are left to dry before being burned as fuel. One of the problems with peat is that it takes a long time to form, growing at a mean rate of 1 mm/year in a typical peat wetland. It is thus regarded as a semi‐renewable fuel. However, in many areas, the rate of exploitation far exceeds the rate of re‐growth, resulting in denudation of the peat bog and increased run‐off of water, leading to flooding.

Peat is a less efficient fuel than coal and natural gas, which means that per unit of energy, peat releases twice as much CO2 as natural gas and 15% more than coal. This  difference is only partly mitigated by the slow renewal of peat fuel (as men-tioned above). Large‐scale peat fires, sometimes initiated by lightning strikes and sometimes by illegal ‘slash and burn’ activities, in addition to releasing large amounts of CO2 into the air, also cause very extensive particulate pollution. One of us was working in Singapore during the notorious 1997 Southeast Asia haze, caused by ille-gal burning of forest trees and subsequent out‐of‐control peat fires in Indonesia. Visibility was very poor, the air smelt of smoke and we were advised not to exercise outside. Right across the region there were deleterious effects on human and animal health. Similar hazes have occurred several times since 1997, as exemplified in Figure 1.1.

Peat may be regarded as being on its way to becoming a fossil fuel. However, the true fossil fuels are coal (including lignite), oil and natural gas. We thus move on to discuss the history of their use.

3 See also Hoare P (2008).

Biofuels and Bioenergy4

1.3 Fossil Fuels

1.3.1 Coal

On Caerphilly Common, between Cardiff and Caerphilly in South Wales, are some shallow depressions and some small mounds. These are the remains of bell pits and their associated spoil tips, providing evidence of coal mining in the area dating from the 14th century. However, use of coal as a fuel for heating, cooking and even smelting met-als actually goes back several thousand years. Its use was recorded in China at around 1000 bc and in Ancient Greece at around 350 bc. In Britain, surface or outcrop coal has been used since the Bronze Age (2000–3000 bc). In Roman times, houses and baths were heated by burning coal and a brazier of coal was kept permanently alight in the Temple of Minerva in Aquae Sulis (now known as Bath). The Romans also used coal for smelting iron.

However, it was not until the end of the 18th century that coal mining became really organised. Those simple bell pits at Caerphilly Common were tapping into the enor-mous South Wales coalfield and it was coal mined from this field that fuelled the Industrial Revolution in that part of Britain. Indeed, the Industrial Revolution led to a large increase in the demand for coal, which was mined in nearly all of the countries in which industry was increasing. Coal mining in the UK has nearly ended now, not because stocks have run out but because it has become uneconomical to mine it. Nevertheless, coal is still mined in many other countries and known global reserves will last for centuries, even taking into account the acceleration in use in countries like India

Figure 1.1 Haze over Singapore 2013.