Biodiesel: A Realistic Fuel Alternative for Diesel Engines

214 Pages·2008·4.07 MB·English

by  Ayhan Demirbas (auth.)

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
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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 es-
ter-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 engi-
neers, 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, bio-
methanol, 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 applica-
tions 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 perform-
ance 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 dec-
ades. 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 petro-
leum gas, and natural gas. An alternative fuel to petrodiesel must be technically
feasible, economically competitive, environmentally acceptable, and easily avail-
able. 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 agri-
culture, 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