Biodiesel
Ayhan Demirbas Biodiesel A Realistic Fuel Alternative for Diesel Engines 123
Ayhan Demirbas Professor of Energy Technology Sila Science and Energy Trabzon Turkey ISBN 978-1-84628-994-1 e-isbn 978-1-84628-995-8 DOI 10.1007/978-1-84628-995-8 British Library Cataloguing in Publication Data Demirbas, Ayhan Biodiesel : a realistic fuel alternative for diesel engines 1. Biodiesel fuels I. Title 662.8'8 ISBN-13: 9781846289941 Library of Congress Control Number: 2007942233 2008 Springer-Verlag London Limited Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms of licences issued by the Copy-right Licensing Agency. Enquiries concerning reproduction outside those terms should be sent to the publishers. The use of registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant laws and regulations and therefore free for general use. The publisher makes no representation, express or implied, with regard to the accuracy of the information contained in this book and cannot accept any legal responsibility or liability for any errors or omissions that may be made. Cover design: estudio Calamar S.L., Girona, Spain Printed on acid-free paper 9 8 7 6 5 4 3 2 1 springer.com
Preface This book aims to provide a comprehensive treatment of triglycerides (oils and fats), which convert primary forms of energy into a more usable and economical source of energy for transportation. Biodiesel is a domestic fuel for diesel engines derived from natural oils like soybean oil. It is the name given to a variety of ester-based oxygenated fuels from renewable biological sources that can be made from processed organic oils and fats. The text is geared toward postgraduates in energy-related studies, fuel engineers, scientists, energy researchers, industrialists, policymakers, and agricultural engineers and assumes the reader has some understanding of the basic concepts of transportation fuels. The first chapter, Introduction to energy sources, comprises one fifth of the book; the chapter goes into detail on global energy sources, especially renewables, i.e., biomass, hydro, wind, solar, geothermal, and marine. The second chapter is entitled Biofuels and covers the main liquid biofuels such as bioethanol, biomethanol, and liquid fuels from Fischer Tropsch synthesis. The third chapter, Vegetable oils and animal fats, covers the use of vegetable oils and animal fats in fuel engines. Furthermore, processing conditions as well as alternative applications of fatty acid methyl esters are discussed briefly in subsequent chapters- Biodiesel, Biodiesel from triglycerides via transesterification, Fuel properties of biodiesels, Current technologies in biodiesel production, Engine performance tests, Global renewable energy and biofuel scenarios, and The biodiesel economy and biodiesel policy. Experts suggest that current oil and gas reserves will last only a few more decades. To meet rising energy demands and compensate for diminishing petroleum reserves, fuels such as biodiesel and bioethanol are in the forefront of alternative technologies. It is well known that transport is almost totally dependent on fossil-, particularly petroleum-, based fuels such as gasoline, diesel fuel, liquefied petroleum gas, and natural gas. An alternative fuel to petrodiesel must be technically feasible, economically competitive, environmentally acceptable, and easily available. Accordingly, the viable alternative fuel for compression-ignition engines is biodiesel. Biodiesel use may improve emission levels of some pollutants and v
vi Preface worsen that of others. The use of biodiesel will allow for a balance between agriculture, economic development, and the environment. The manuscript for this text was reviewed by Anthony Doyle and Simon Rees. I would like to thank the publisher s editorial staff, all of whom have been most helpful. Trabzon, TURKEY, May 2007 Ayhan Demirbas
Contents 1 Introduction... 1 1.1 Introduction to Energy Sources... 1 1.2 Global Energy Sources and the Present Energy Situation... 3 1.3 Renewable Energy Sources... 6 1.3.1 Biomass Energy and Biomass Conversion Technologies... 8 1.3.2 Hydropower... 23 1.3.3 Geothermal Energy... 24 1.3.4 Wind Energy... 25 1.3.5 Solar Energy... 27 1.3.6 Biohydrogen... 28 1.3.7 Other Renewable Energy Sources... 30 References... 33 2 Biofuels... 39 2.1 Introduction to Biofuels... 39 2.2 Bioethanol... 42 2.3 Biomethanol... 45 2.4 Biohydrogen from Biomass by Steam Reforming... 49 2.4.1 Steam-reforming Process... 50 2.4.2 Fuels from Bio-syngas via Fischer Tropsch Synthesis... 51 2.5 Biodiesel... 56 2.6 Bio-oil... 57 2.7 Global Biofuel Scenarios... 59 References... 60 3 Vegetable Oils and Animal Fats... 65 3.1 Use of Vegetable Oils and Animal Fats in Fuel Engines... 65 3.2 Vegetable Oil Resources... 67 3.2.1 Inedible Oil Resources... 69 vii
viii Contents 3.3 Vegetable Oil Processing... 72 3.3.1 Recovery of Vegetable Oils from Plants... 72 3.3.2 Vegetable Oil Refining... 73 3.4 The Use of Vegetable Oils as Diesel Fuel... 74 3.4.1 Physical and Chemical Properties of Vegetable Oils... 75 3.4.2 Direct Use of Vegetable Oils in Diesel Engines... 79 3.5 New Engine Fuels from Vegetable Oils... 83 3.5.1 Pyrolysis of Vegetable Oils and Fats... 83 3.5.2 Cracking of Vegetable Oils... 85 3.5.3 Pyrolysis Mechanisms of Vegetable Oils... 86 3.6 Gasoline-rich Liquid from Sunflower Oil by Alumina Catalytic Pyrolysis... 88 3.7 Diesel-like Fuel from Tallow (Beef) by Pyrolysis and Steam Reforming... 91 3.8 Converting Triglyceride-derived Synthetic Gas to Fuels via Fischer Tropsch Synthesis... 95 3.9 Triglyceride Analyses... 99 3.9.1 Viscosity... 99 3.9.2 Density... 100 3.9.3 Cetane Number... 100 3.9.4 Cloud and Pour Points... 101 3.9.5 Distillation Range... 101 3.9.6 Heat of Combustion... 101 3.9.7 Water Content... 102 3.9.8 Discussion of Fuel Properties of Triglycerides... 102 3.10 Triglyceride Economy... 105 References... 105 4 Biodiesel... 111 4.1 Introduction to Biodiesel Concept... 111 4.2 History... 112 4.3 Definitions... 114 4.4 Biodiesel as an Alternative to Diesel Engine Fuel... 115 4.5 Sources of Biodiesel... 117 References... 118 5 Biodiesel from Triglycerides via Transesterification... 121 5.1 Biodiesel from Triglycerides via Transesterification... 121 5.1.1 Catalytic Transesterification Methods... 123 5.1.2 Supercritical Alcohol Transesterification... 125 5.1.3 Biocatalytic Transesterification Methods... 132 5.1.4 Recovery of Glycerine... 133
Contents ix 5.1.5 General Reaction Mechanism of Transesterification... 133 5.1.6 Esterification of Fatty Acids with Diazomethane... 137 5.1.7 Non-catalytic Supercritical Alcohol Transesterification... 137 5.1.8 Enzyme-catalyzed Processes... 138 References... 139 6 Fuel Properties of Biodiesels... 141 6.1 Viscosity, Density, and Flash Point... 141 6.2 Cetane Number, Cloud Point, and Pour Point... 144 6.3 Characteristics of Distillation Curves... 145 6.4 Higher Combustion Efficiency of Biodiesel... 145 6.5 Water Content... 146 6.6 Comparison of Fuel Properties and Combustion Characteristics of Methyl and Ethyl Alcohols and Their Esters... 146 6.7 Advantages and Disadvantages of Biodiesels... 151 6.7.1 Advantages of Biodiesel as Diesel Fuel... 151 6.7.2 Availability and Renewability of Biodiesel... 151 6.7.3 Lower Emissions from Biodiesel... 152 6.7.4 Biodegradability of Biodiesel... 155 6.7.5 Thermal Degradation of Fatty Acids During Biodiesel Production... 156 6.7.6 Disadvantages of Biodiesel as Diesel Fuel... 157 References... 158 7 Current Technologies in Biodiesel Production... 161 7.1 Biodiesel Production Processes... 166 7.1.1 Primary Raw Materials Used in Biodiesel Production... 166 7.1.2 Biodiesel Production with Batch Processing... 167 7.1.3 Biodiesel Production with Continuous Process... 168 7.1.4 Biodiesel Production with Non-catalyzed Transesterification... 169 7.1.5 Basic Plant Equipment Used in Biodiesel Production... 171 References... 172 8 Engine Performance Tests... 175 8.1 Engine Combustion Process and Combustion-related Concepts... 177 8.2 Engine Performance Tests... 179 8.2.1 Alcohol-diesel Emulsions... 179 8.2.2 Using Microemulsions for Vegetable Oil... 180 8.2.3 Diesel Engine Fumigation... 180 8.2.4 Dual Injection... 180 8.2.5 Injector Coking... 181
x Contents 8.2.6 Heated Surfaces... 181 8.2.7 Torque Tests... 181 8.2.8 Spark Ignition... 181 8.2.9 Oxidation... 182 References... 182 9 Global Renewable Energy and Biofuel Scenarios... 185 9.1 Global Renewable Energy Sources... 187 9.2 Renewable Energy Scenarios... 189 References... 193 10 The Biodiesel Economy and Biodiesel Policy... 195 10.1 Introduction to the Biodiesel Economy... 195 10.2 Economic Benefits of Biodiesel... 197 10.3 Biodiesel Costs... 199 10.4 General Biodiesel Policy... 201 10.5 European Biofuel Policy... 202 References... 203 Index... 205