Practical Handbook on Biodiesel Production and Properties

Practical Handbook onBiodiesel Production

and Properties

CHEMICAL INDUSTRIESA Series of Reference Books and Textbooks

Founding Editor

HEINZ HEINEMANNBerkeley, California

Series Editor

JAMES G. SPEIGHTCD & W, Inc.

Laramie, Wyoming

MOST RECENTLy PUbLISHED

Practical Handbook on Biodiesel Production and Properties, Mushtaq Ahmad, Mir Ajab Khan, Muhammad Zafar, and Shazia Sultana

Introduction to Process Control, Second Edition, Jose A. Romagnoli and Ahmet Palazoglu

Fundamentals of Petroleum and Petrochemical Engineering, Uttam Ray ChaudhuriAdvances in Fluid Catalytic Cracking: Testing, Characterization, and

Environmental Regulations, edited by Mario L. OccelliAdvances in Fischer-Tropsch Synthesis, Catalysts, and Catalysis,

edited by Burton H. Davis and Mario L. OccelliTransport Phenomena Fundamentals, Second Edition, Joel PlawskyAsphaltenes: Chemical Transformation during Hydroprocessing of Heavy Oils,

Jorge Ancheyta, Fernando Trejo, and Mohan Singh RanaChemical Reaction Engineering and Reactor Technology, Tapio O. Salmi,

Jyri-Pekka Mikkola, and Johan P. WarnaLubricant Additives: Chemistry and Applications, Second Edition,

edited by Leslie R. RudnickCatalysis of Organic Reactions, edited by Michael L. PrunierThe Scientist or Engineer as an Expert Witness, James G. SpeightProcess Chemistry of Petroleum Macromolecules, Irwin A. WieheInterfacial Properties of Petroleum Products, Lilianna Z. PillonClathrate Hydrates of Natural Gases, Third Edition, E. Dendy Sloan and

Carolyn KohChemical Process Performance Evaluation, Ali Cinar, Ahmet Palazoglu,

and Ferhan KayihanHydroprocessing of Heavy Oils and Residua, edited by James G. Speight

and Jorge AncheytaProcess Chemistry of Lubricant Base Stocks, Thomas R. LynchCatalysis of Organic Reactions, edited by Stephen R. Schmidt

CRC Press is an imprint of theTaylor & Francis Group, an informa business

Boca Raton London New York

Mushtaq Ahmad Mir Ajab KhanMuhammad Zafar Shazia Sultana

Practical Handbook onBiodiesel Production

and Properties

CRC PressTaylor & Francis Group6000 Broken Sound Parkway NW, Suite 300Boca Raton, FL 33487-2742

2013 by Taylor & Francis Group, LLCCRC Press is an imprint of Taylor & Francis Group, an Informa business

No claim to original U.S. Government worksVersion Date: 20120525

International Standard Book Number-13: 978-1-4665-0744-9 (eBook - PDF)

This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint.

Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmit-ted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers.

For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged.

Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe.Visit the Taylor & Francis Web site athttp://www.taylorandfrancis.comand the CRC Press Web site athttp://www.crcpress.com

vContentsList of Figures ..........................................................................................................viiList of Tables .............................................................................................................ixPreface.......................................................................................................................xiAbout the Authors .................................................................................................. xiiiAbout This Book ......................................................................................................xv

Chapter 1 Introduction to Biodiesel ......................................................................1

1.1 Biodiesel: A Historical Overview ..............................................11.2 Biodiesel: An Alternative Fuel ..................................................11.3 Biodiesel Market ........................................................................21.4 Biodiesel Advantages ................................................................41.5 Biodiesel Impacts ......................................................................4

1.5.1 Financial Impacts .........................................................41.5.2 Environmental and Sustainable Impacts ......................51.5.3 Biodiesel and Biodiversity Conservation .....................51.5.4 Socioeconomic Impacts ...............................................61.5.5 Health Impacts .............................................................61.5.6 Agricultural Impacts ....................................................71.5.7 Biodiesel and Energy Security .....................................91.5.8 Technical Impacts ...................................................... 10

Chapter 2 Biodiesel Production .......................................................................... 11

2.1 Global Biodiesel Sources ......................................................... 112.2 Chemistry of Oil and Biodiesel ............................................... 122.3 Oil Extraction .......................................................................... 172.4 Commercial Oil Extraction ..................................................... 192.5 Biodiesel Synthesis ..................................................................20

2.5.1 Pyrolysis ..................................................................... 212.5.2 Dilution ....................................................................... 212.5.3 Microemulsion............................................................ 212.5.4 Transesterification ...................................................... 212.5.5 Base-Catalyzed Transesterification ............................222.5.6 Acid-Catalyzed Transesterification ............................222.5.7 Lipase-Catalyzed Transesterification .........................23

2.6 Factors Affecting Transesterification Reaction .......................242.6.1 Effect of FFA and Moisture Content ..........................252.6.2 Effect of Catalyst ........................................................262.6.3 Effect of Alcohol/Triglyceride Molar Ratio ...............282.6.4 Effect of Reaction Time and Temperature .................292.6.5 Effect of Mixing Intensity ..........................................29

vi Contents

2.7 Biodiesel Fuel Properties .........................................................302.8 Biodiesel: Technical Aspects ................................................... 32

2.8.1 Combustion Characteristics ....................................... 322.8.2 Engine Emission Characteristics ................................ 332.8.3 Engine Performance Characteristics ..........................342.8.4 Biodiesel Economics .................................................. 35

Chapter 3 Biodiesel Yielding Plants and Fuel Properties ................................... 37

3.1 Canola ...................................................................................... 373.2 Carthame ................................................................................. 423.3 Castor Bean ............................................................................. 473.4 Cotton ...................................................................................... 523.5 Indian Hemp ............................................................................ 573.6 Jatropha .................................................................................... 623.7 Linseed .................................................................................... 673.8 Milk Thistle ............................................................................. 723.9 Mustard ....................................................................................773.10 Neem ........................................................................................ 823.11 Peanut ......................................................................................873.12 Pongame ..................................................................................923.13 Rice Bran .................................................................................973.14 Rocket Seed ........................................................................... 1023.15 Sesame ................................................................................... 1073.16 Soybean ................................................................................. 1123.17 Sunflower ............................................................................... 1173.18 White Mustard ....................................................................... 122

Glossary ................................................................................................................ 127

References ............................................................................................................. 135

vii

List of FiguresPlate No. Figure Caption Page No.

2.1 Biodiesel preparation flow sheet 18

2.2 Oil extraction by conventional method 18

2.3 Electric oil expeller 19

2.4 A small unit lab oil expeller 20

2.5 Oil filtration 23

2.6 Heating of oil 24

2.7 Catalyst preparation 25

2.8 Biodiesel separation from glycerin 28

2.9 Transesterification kit with methanol recovery unit 30

2.10 Biodiesel blends of rapeseed oil 32

3.1 (a)Canola plant; (b)canola seeds; (c)canola biodiesel; (d)canola SEM pollen; (e)canola oil cake; (f)canola glycerin; (g)canola soap

3941

3.2 (a)Carthame plant; (b)carthame seeds; (c)carthame biodiesel; (d)carthame SEM pollen; (e)carthame oil cake; (f)carthame glycerin; (g)carthame soap

4446

3.3 (a)Castor bean plant; (b)castor bean seeds; (c)castor bean biodiesel; (d)castor bean SEM pollen; (e)castor bean oil cake; (f)castor bean glycerin; (g)castor bean soap

4951

3.4 (a)Cotton plant; (b)cotton seeds; (c)cotton biodiesel; (d)cotton SEM pollen; (e)cotton oil cake; (f)cotton glycerin; (g)cotton soap

5456

3.5 (a)Indian hemp plant; (b)Indian hemp seeds; (c)Indian hemp biodiesel; (d)Indian hemp SEM pollen; (e)Indian hemp oil cake; (f)Indian hemp glycerin; (g)Indian hemp soap

5961

3.6 (a)Jatropha plant; (b)jatropha seeds; (c)jatropha biodiesel; (d)jatropha SEM pollen; (e)jatropha oil cake; (f)jatropha glycerin; (g)jatropha soap

6466

3.7 (a)Linseed plant; (b)linseed seeds; (c)linseed biodiesel; (d)linseed SEM pollen; (e)linseed oil cake; (f)linseed glycerin; (g)linseed soap

6971

3.8 (a)Milk thistle plant; (b)milk thistle seeds; (c)milk thistle biodiesel; (d)milk thistle SEM pollen; (e)milk thistle oil cake; (f)milk thistle glycerin; (g)milk thistle soap

7476

3.9 (a)Mustard plant; (b)mustard seeds; (c)mustard biodiesel; (d)mustard SEM pollen; (e)mustard oil cake; (f)mustard glycerin; (g)mustard soap

7981

3.10 (a)Neem plant; (b)neem seeds; (c)neem biodiesel; (d)neem SEM pollen; (e)neem oil cake; (f)neem glycerin; (g)neem soap

8486

3.11 (a)Peanut plant; (b)peanut seeds; (c)peanut biodiesel; (d)peanut SEM pollen; (e)peanut oil cake; (f)peanut glycerin; (g)peanut soap

8991

3.12 (a)Pongame plant; (b)pongame seeds; (c)pongame biodiesel; (d)pongame SEM pollen; (e)pongame oil cake; (f)pongame glycerin; (g)pongame soap

9496

3.13 (a)Rice bran plant; (b)rice bran seeds; (c)rice bran biodiesel; (d)rice bran SEM pollen; (e)rice bran oil cake; (f)rice bran glycerin; (g)rice bran soap

99101

3.14 (a)Rocket seed plant; (b)rocket plant seeds; (c)rocket seed biodiesel; (d)rocket seed SEM pollen; (e)rocket seed oil cake; (f)rocket seed glycerin; (g)rocket seed soap

104106

viii List of Figures

Plate No. Figure Caption Page No.

3.15 (a)Sesame plant; (b)sesame seeds; (c)sesame biodiesel; (d)sesame SEM pollen; (e)sesame oil cake; (f)sesame glycerin; (g)sesame soap

109111

3.16 (a)Soybean plant; (b)soybean seeds; (c)soybean biodiesel; (d)soybean SEM pollen; (e)soybean oil cake; (f)soybean glycerin; (g)soybean soap

114116

3.17 (a)Sunflower plant; (b)sunflower seeds; (c)sunflower biodiesel; (d)sunflower SEM pollen; (e)sunflower oil cake; (f)sunflower glycerin; (g)sunflower soap

119121

3.18 (a)White mustard plant; (b)white mustard seeds; (c)white mustard biodiesel; (d)white mustard SEM pollen; (e)white mustard oil cake; (f)white mustard glycerin; (g)white mustard soap

124126

ix

List of TablesTable No. Table Title Page No.

2.1 Comparative Fuel Specification of Biodiesel 14

3.1 Fuel Properties of Canola Biodiesel Blends 38

3.2 Fuel Properties of Safflower Biodiesel Blends 43

3.3 Fuel Properties of Castor Bean Biodiesel Blends 48

3.4 Fuel Properties of Cotton Biodiesel Blends 53

3.5 Fuel Properties of Indian Hemp Biodiesel Blends 58

3.6 Fuel Properties of Jatropha Biodiesel Blends 63

3.7 Fuel Properties of Linseed Biodiesel Blends 68

3.8 Fuel Properties of Milk Thistle Biodiesel Blends 73

3.9 Fuel Properties of Mustard Biodiesel Blends 78

3.10 Fuel Properties of Neem Biodiesel Blends 83

3.11 Fuel Properties of Peanut Biodiesel Blends 88

3.12 Fuel Properties of Pongame Biodiesel Blends 93

3.13 Fuel Properties of Rice Bran Biodiesel 98

3.14 Fuel Properties of Rocket Seed Biodiesel Blends 103

3.15 Fuel Properties of Sesame Biodiesel Blends 108

3.16 Fuel Properties of Soybean Biodiesel Blends 113

3.17 Fuel Properties of Sunflower Biodiesel Blends 118

3.18 Fuel Properties of White Mustard Biodiesel Blends 123

xi

PrefaceBiodiesel is a diesel fuel substitute produced from vegetable oils, algae, animal fats, and recycled cooking oils. It is one of the most important renewable natural resources for an agrarian country. Biodiesel technology is a new priority in efforts to reduce dependence on fossil fuels and the environmental problems caused by the use of those fossil fuels. The justification for developing biodiesel as an alternate fuel is manifold; rising crude oil prices and vulnerability of energy security are the two biggest reasons. In view of this, an effort has been made in this book to assemble and analyze the practical research information on biodiesel from oil seed plants. The present book is a compilation on the recent trends of biodiesel research, production, and implementation. It includes practical research and activities with reference to identification of plant resources, distribution, botanical description, palynology, oil extraction, production process, biodiesel yield, product photography, and fuel prop-erty comparison with petrodiesel.

The authors are thankful to the Higher Education Commission (HEC) of Pakistan and Quaid-i-Azam University (QAU), Islamabad, Pakistan, for providing financial support to conduct research projects on biodiesel. They are also thankful to the Taylor & Francis Group for publishing and printing this book for global circula-tion. It is hoped that this book will serve as a valuable reference for identification of biodiesel resources for commercial production and properties, as well as useful for researchers and policy makers in plant biology and agriculture.

Mushtaq AhmadMir Ajab Khan

Muhammad ZafarShazia Sultana

Quaid-i-Azam University

xiii

About the AuthorsMushtaq Ahmad obtained his PhD in 2008 in plant sys-tematics and biodiversity from Quaid-i-Azam University, Islamabad, Pakistan. He has published to date 210 research articles in various journals of repute. He has published 10 international books. His research work has concentrated on biofuel technology, medicinal plants, and biodiversity conservation. Currently, Dr. Ahmad is working as assistant professor in the Department of Plant Sciences, Quaid-i-Azam University ([email protected]).

Mir Ajab Khan obtained his PhD in 1984 in plant biosystematics from Leicester University, England. He has 30 years of teaching and research activities in plant taxonomy and biosystematics. He has produced 35 PhD and 80 MPhil research students. Prof. Dr. Khan has pub-lished 350 scientific papers in different national and for-eign journals and 11 books on various aspects of plant sciences ([email protected]).

Muhammad Zafar is working as herbarium bota-nist in the Department of Plant Sciences at Quaid-i-Azam University, Islamabad, Pakistan. Dr. Zafar has published 150 research papers in different journals of repute. He has produced 10 international books. His research interests are medicinal plants, biodiesel, and herbarium management ([email protected]).

xiv About the Authors

Shazia Sultana earned her PhD in plant systematics and biodiversity from the Department of Plant Sciences at Quaid-i-Azam University, Islamabad, Pakistan. She has published 60 research papers in national and international journals of repute and is author of two international books. Her research interests are medici-nal plants, pharmacognosy, and biodiesel technology ([email protected]).

xv

About This BookThis book was written in the belief that learning about techniques can enable more people to understand biofuel technology. Moreover, production and usage of biodiesel will strengthen the agricultural sector, provide energy to remote areas where conventional energy cannot be taken, contribute toward grassroots poverty alleviation, and increase industrial activity. The book draws on both scientific and participatory processes, supported by the experience of authors from across the subjects field.

Dr. Mushtaq Ahmad, Prof. Dr. Mir Ajab Khan, Dr. Muhammad Zafar, and Dr.Shazia Sultana are a group of researchers who are experts in biofuel technology. They have been pioneers in introducing this new, emerging technology into Pakistan in terms of identification of indigenous oil-yielding plant species and their biodiesel potential and establishing a new discipline at a universityindustry level. They have produced a number of young researchers and publications in this field at global lev-els. Their efforts in compiling this book, based on their practical research activities in the laboratory and the field, will be a valuable reference for researchers, breed-ers, industrialists, and policy makers in biology and agriculture. This book presents core information on identification of biodiesel resources, production processes, and fuel properties analysis and techniques through beautiful illustrations, helping more people to use and commercialize this technology.

11 Introduction to Biodiesel1.1 BIODIESEL:AHISTORICALOVERVIEW

Biodiesel refers to a vegetable oil or animal fat-based diesel fuel consisting of long-chain alkyl (methyl, propyl, or ethyl) esters. Biodiesel is typically made by chemi-cally reacting lipids (e.g., vegetable oil, animal fat) with an alcohol. In 1900 Rudolf Diesel (German inventor of the diesel engine) demonstrated his compression ignition engine using peanut oil at the World Exhibition in Paris. He delivered a speech in 1912, stating that the use of vegetable oils for engine fuels may seem insignificant today but such oils may become in the course of time as important as petroleum and coal-tar products of the present time. Despite Rudolf Diesels vision from a century ago, biodiesel is still the relative kid on the biodiesel block, having gained signifi-cant momentum only since the start of the new millennium (Borgman 2007).

Vegetable oils were used until the 1920s, when a modification was made to the engine that enabled it to use a residue of petroleum diesel. Although the diesel engine gained worldwide acceptance, biodiesel did not. With its superior price, availability, and government subsidies, petroleum diesel quickly became the choice for the diesel engine. In the mid-1970s, a fuel shortage revived interest in developing biodiesel as an alternative to petroleum diesel. However, as the petroleum market was increas-ingly subsidized, biodiesel was again relegated to a minority alternative status. These political and economic struggles continue to limit the impact of the biodiesel industry today (McDonnell, Shane, and McNulty 1999). Biodiesel was introduced in South Africa before World War II to power heavy-duty vehicles. Recent environ-mental and domestic economic concerns have promoted resurgence in the use of biodiesel throughout the world. In 1991 the European Community (EC) produced a 90% tax reduction for the use of biofuel including biodiesel. Biodiesel plants are now manufactured by several companies in Europe. Each of these plants produces up to 5.7 million liters (1.5 million gallons) of fuel per year (Peterson 2007).

1.2 BIODIESEL:ANALTERNATIVEFUEL

Diesel fuels have an important role in the industrial economy of any country. High energy demand in the industrialized world and widespread use of fossil fuels are leading to fast depletion of fossil fuel resources as well as environmental degradation. The world petroleum reserves are so unevenly distributed that many regions have to depend on others for their fuel requirements. Degrading air quality due to emissions is the main adverse effect of petroleum-based fuels. All these factors necessitate continued search and sustainable development of renewable energy sources that are environmentally friendly.

Biomass sources, particularly vegetable oils, have attracted much attention as an alternative energy source. They are renewable and nontoxic and can be produced

2 Practical Handbook on Biodiesel Production and Properties

locally from agriculture and plant resources. Their utilization associated with adverse effects on the environment depends on the biodiesel source material or for-mulation and type of engine. Saturated biodiesel exhibits lower NOx emission, but NOx increase with biodiesel is observed for heavy-duty engines. Generally, biodie-sel emits less harmful emissions and greenhouse gases (Sinha, Agarwal, and Garg 2008; Ahmad et al. 2010).

In recent years systematic efforts have been made to utilize vegetable oil as fuel in engines. Mineral diesel fuel is a complex mixture with carbon atoms ranging between 12 and 18, whereas vegetable oils are a mixture of organic compounds ranging from simple straight chain compounds to complex structures of proteins and fat-soluble vitamins and are commonly referred to as triglycerides (Srivastava and Verma 2008). Vegetable oils are usually triglycerides, generally with a number of branched chains of different lengths and different degrees of saturation. Vegetable oils have about 10% lower heating value than mineral diesel due to the oxygen pres-ent in their molecules. The viscosity of vegetable oil is several times higher than that of mineral diesel due to its large molecular mass and chemical structure. The cloud point and pour point are higher, and the cetane number is comparable to that of min-eral diesel (Barnwal and Sharma 2005).

The high viscosity of vegetable oils (30200 cSt) as compared to mineral diesel oil (4 cSt) at 40C leads to unfavorable pumping and spray characteristics. The inef-ficient mixing of fuel with air contributes to incomplete combustion. The high flash point and lower volatility characteristics result in increased carbon deposit forma-tion, injector coking, and lubricating oil dilution and degradation. With vegetable oil as a fuel, short-term engine performance results are comparable to those with mineral diesel, but long-term results with vegetable oil or blends with mineral diesel lead to severe engine deposits, piston ring sticking, injector coking, and thickening of the lube oil (Peterson et al. 1991).

Vegetable oils need to be modified to bring their combustion-related properties closer to those of mineral diesel. The fuel modification is mainly aimed at reducing the viscosity and increasing the volatility. Considerable efforts have been made to develop vegetable oil derivatives that approximate the properties and performance of the hydrocarbon fuels (Agarwal et al. 1989). The best way to make vegetable oil compatible with existing engines is to convert it into methyl ester (biodiesel).

In comparison to mineral diesel, biodiesel has a more favorable combustion and emission profile. Emissions of CO and particulate matter decrease by 45% and hydrocarbon (HC) emissions decrease by nearly 70%, but NOx emissions increase by 10% with 100% biodiesel (B100) as a fuel (Anonymous 2002). The carbon cycle time for fixation of CO2 from biodiesel is quite small compared to mineral diesel. It means that biodiesel usage reduces greenhouse gas emissions compared to mineral diesel (Culuba 2004). Biodiesel has a relatively high flash point, which makes it safer to handle (Agarwal et al. 1989).

1.3 BIODIESELMARKET

The solution of economic and ecological problems at national and international lev-els strongly influences the development of new technologies. The problem of the

3Introduction to Biodiesel

greenhouse effect related to the emission of CO2 gases and environmental air pol-lution with harmful components of exhaust gases charges competitive national and international organizations to regulate and to reduce harmful emissions in the envi-ronment. The replacement of mineral fuel with biodiesel is one of the most effective ways for solving the economic and environmental problems in the transport sector. The directive of the European Union mentions the actuality of this solution, which promotes the application of biodiesel and other alternative fuels in a transport sector with growing tendencies: 5.75% of total fuel consumption by 2010 and 20% by 2020 (Lebedevas and Vaicekauskas 2006).

Metropolitan public transit buses and school buses are both significant users of die-sel fuel and represent a growing market segment for biodiesel blend. The desire to meet clean air standards and reduce carbon monoxide, hydrocarbon, and particulate emis-sions from buses has led metropolitan areas in many parts of the world to consider and experiment with biodiesel blends or at least to consider doing so. One approach to reduc-ing biodiesel NOx and other emissions to a level equal to that from conventional diesel involves either increasing the cetane number (CN) or decreasing aromatics. Another approach to obtain cleaner aspects of biodiesel is to blend low-aromatic or high-cetane components, such as alkylate or FischerTropsch (FT) diesel into biodiesel.

Some school districts are also experimenting with blends as a strategy to provide healthier air and environment for students. US school buses currently log approxi-mately 4 billion miles per year and represent a significant potential market. The market for biodiesel is by no means fully developed yet, but it has shown excel-lent growth over the last decade. The market consists of a number of segments and demand growth appears to be occurring in most of them. Those considering biodie-sel production will need to monitor these segments and the regulatory framework surrounding them as they conduct their feasibility analyses and establish their busi-ness plans (Ginder 2004).

The continued expansion of the biodiesel market is dependent upon the develop-ment of production and distribution systems that are intensely focused on consistent and high-quality supplies of biodiesel. Biodiesel as a substitute for petroleum diesel is just beginning to establish a market in the United States and biodiesel is most commonly blended with conventional diesel fuel at a level of 20% or lower. The majority of the 75 million gallons of biodiesel produced in 2005 came from soybean oil, although it can also be made from other oilseed plants, animal fats, and grease.

Renewable fuels have gained momentum not only in the United States but also around the world. A significantly higher portion of Europes vehicles are diesel pow-ered and, as a result, the production of biodiesel derived from rapeseed has expanded rapidly. With the relative cost of diesel fuel significantly higher, the future for renew-able biodiesel in Europe is very bright (Borgman 2007).

In recent times, the world has been confronted with an energy crisis due to deple-tion of resources and increased environmental problems. The situation has led to the search for an alternative fuel, which should be not only sustainable but also envi-ronmentally friendly. For developing countries, fuels of bio-origin, such as alcohol, vegetable oils, biomass, biogas, synthetic fuels, etc., are becoming important. Such fuels can be used directly, while others need some sort of modification before they are used as substitutes for conventional fuels (Barnwal and Sharma 2005).


1.4 BIODIESELADVANTAGES

The use of biodiesel and its blends, like B5 (5% biodiesel + 95% petrodiesel), B10 (10% biodiesel + 90% petrodiesel), B20 (20% biodiesel + 80% petrodiesel), B50 (50% biodiesel + 50% petrodiesel), and B100 (100% pure biodiesel) can reduce the net emissions of greenhouse gases. The net effect of biodiesel use results in an over-all decrease in ozone formation, an important environmental issue. The emissions produced by burning of biodiesel are less reactive with sunlight than those produced by burning gasoline, which results in a lower potential for forming the damaging ozone. Biodiesel is considered a renewable energy resource because it is primarily the result of conversion of the suns energy into usable energy. Among the key advan-tages of biodiesel are:

It is made from renewable resources. It performs just as well as normal diesel fuel. It causes less pollution as compared to diesel-powered engines. It is relatively less inflammable compared to normal diesel. It can be mixed with normal diesel fuel. It is biologically degradable and reduces the danger of contamination of soil

and underground water during transport, storage, and use. It contains no sulfur, the element responsible for acid rain. It is economical because there are no extra costs for the conversion of

engines in comparison to other biological fuels. It prolongs the life of an engine. Its refineries are comparatively simpler and more environmentally friendly

in design than typical petrochemical refineries. It emits generally less carbon dioxide (CO2) than normal diesel fuel. It has a higher cetane and lubricity rating than pure petroleum-based diesel

fuel, which improves engine efficiency and operating life cycle.

1.5 BIODIESELIMPACTS

Biodiesel, which is a relatively clean-burning, renewable fuel produced from vegetable oils, algae, nonfood oilseed crops, agricultural wastes, and animal fats could be used to replace at least a portion of the diesel fuel consumed daily. Integrated benefits can be realized at the society, industry, and the government level in the form of environ-mental, economical, social, and health benefits. Biodiesel can be used in almost any normal internal-combustion diesel engine and can be stored and transported using existing infrastructure and equipment already used for regular petroleum diesel.

1.5.1 Financialimpacts

Biodiesel keeps our fuel-buying money at home instead of sending it to foreign coun-tries for import of fossil fuel. This reduces our trade deficit and creates new jobs. Biodiesel can be produced by individuals on a small scale relatively inexpensively when compared to petrodiesel. With prices that low, most people are able to save hundreds


of dollars on their fuel bills. With savings like that, most people are able to recoup their initial investment on the equipment needed to make biodiesel within a matter of months. Biodiesel is produced domestically, which means that using biodiesel will create jobs and contribute to local economies through promoting small enterprises.

Biodiesel is cost effective, as it has a much higher lubricity to it. With the added lubricity of biodiesel, engines have been shown to experience less wear and tear when used on a regular basis and, ultimately, less maintenance cost. Carbon credits can be earned by the government, private producers, and users of biodiesel. A new industry can be established that can gradually gain economies of scale as collection and distribution mechanisms for the raw material become recognized. A decentral-ized fuel generation approach can create more business and economic activity.

1.5.2 EnvironmEntalandsustainablEimpacts

Biodiesel generally has less CO2 emissions as compared to conventional dieselmeaning that it contributes to reducing emissions to global warming. When biodie-sel is used to power diesel engines, the emissions at the tailpipe are significantly reduced. Studies by the US National Renewable Energy Lab indicate drops in several key areas that help the environment. Carbon dioxide (CO2), sulfur dioxide (SO2), car-bon monoxide (CO), hydrocarbon (HC), polycyclic aromatic hydrocarbons (PAHs), and particulate matter (the black smoke from diesels) all are significantly reduced when biodiesel is used (Sheehan et al. 1998). The effect on total particulate emis-sions (PEs) depends on engine operating condition.

A number of factors can cause biodiesel emissions to differ significantly from the average values as assessed by the Environmental Protection Agency (EPA). For example, different fuel system designs and engine calibration can result in measur-ably different emission from biodiesel. When it is used in older diesel engines such as indirect combustion diesels, the results are astounding. It has reduced tailpipe emissions up to nearly 90%. The exhausts have smells like popcorn or french fries. Instead of making a fuel from a finite resource such as crude oil, biodiesel can be produced from renewable resources.

1.5.3 biodiEsElandbiodivErsityconsErvation

Among several options of using vegetable oils, nonedible oil feedstock is especially appropriate for biodiesel production. This approach will not only foster the conserva-tion and promotion of indigenous flora but also help to protect and promote native biodiversity by putting barriers on the import of exotic species. When appropriate crops are planted in suitable areas, they can actually benefit biodiversity. This is par-ticularly true where biofuels are grown on marginal and degraded lands (Eickhout et al. 2008). They can increase soil productivity, reduce soil erosion, reduce pressure on natural ecosystems, and create habitats.

Pongame and castor bean are the biofuel crops that can be grown on degraded land, and they are receiving increasing attention, particularly in Africa, Pakistan, and India (Ahmad et al. 2009, 2010, 2011). It has been suggested that these crops can be grown by traditional pastoralists under traditional systems that maintain


biodiversity and that they are not crops used for food production. However, their land and water requirements and suitability for large-scale production are yet to be determined fully, and reports suggest that they will grow better on more productive landmeaning that production on degraded land would need to be incented. On the other hand, some countries currently have biofuel crops on nonsensitive lands (Machado-Filho 2008) or still have large expanses of such land available for energy crop production (UNCTAD 2006).

1.5.4 socioEconomicimpacts

Quality of life can be improved gradually as the environmental and economic haz-ards of petrodiesel will start getting low. The biodiesel industry can help to enhance job opportunities in the market and can create awareness and education among the masses. Biodiesel will create permanent new jobs. The increase in final demand resulting from the combination of new construction and ongoing biodiesel produc-tion will support the creation of more than 39,100 new jobs in all sectors of the economy by 2015. Increased economic activity and new jobs result in higher levels of income. The biodiesel industry will put an additional $627 million into the pockets of American households each year for a total impact of $6.3 billion between 2006 and 2015. Expansion of the biodiesel industry will generate additional tax revenues for government at all levels, from personal and corporate income taxes that increase in line with higher output levels and larger GDP (Urbanchuk 2006).

Expansion of the biodiesel industry as described previously can be expected to generate an estimated $8.3 billion of additional tax revenue for the federal govern-ment and $650 million of revenue for state and local governments between 2006 and 2015. The biodiesel industry will more than pay for itself. The additional tax revenues generated by a profitable biodiesel industry will be significantly larger than the value of the federal tax incentives provided to the industry. Assuming that the biodiesel tax credit of one cent per gallon for agribiodiesel and a half cent per gallon for biodiesel from other sources is extended past 2008, this program would cost $3.5 billion by 2015.

However, as previously indicated, the industry will generate $8.3 billion of new revenue for the federal treasury for a positive net balance of $4.8 billion. The biodie-sel industry will play a significant role in improving Americas energy security. Expansion of the biodiesel industry as discussed before will displace 242 million barrels of crude oil between 2006 and 2015. Since the United States is a net importer of oil, this means that less oil will need to be imported. As a consequence, $13.6 bil-lion will remain in the American economy instead of being sent abroad to finance oil imports (Urbanchuk 2006).

1.5.5 HEaltHimpacts

The reduced levels of air and other forms of pollution, suspended particles, and other socioeconomic benefits have positive impacts on health. As the risk level trims down, it will inversely bump up well-being status. The first tier of health effects testing was conducted by Southwest Research Institute and involved a detailed


analysis of biodiesel emissions. Tier II was conducted by Lovelace Respiratory Research Institute, where a 90-day subchronic inhalation study of biodiesel exhaust with specific health assessments was completed. Results of the health effects testing concluded that biodiesel is nontoxic and biodegradable, posing no threat to human health. Also among the findings of biodiesel emissions compared to petroleum diesel emissions in this testing were the following:

The ozone (smog)-forming potential of hydrocarbon exhaust emissions from biodiesel is 50% less.

The exhaust emissions of carbon monoxide (a poisonous gas and a contrib-uting factor in the localized formation of smog and ozone) from biodiesel are 50% lower.

The exhaust emissions of particulate matter (recognized as a contributing factor in respiratory disease) from biodiesel are comparatively lower. But generally the influence of PM depends on its aerodynamic diameter.

The exhaust emissions of sulfur oxides and sulfates (major components of acid rain) from biodiesel are completely eliminated.

The exhaust emissions of hydrocarbons (a contributing factor in the local-ized formation of smog and ozone) are 95% lower.

The exhaust emissions of aromatic compounds known as polycyclic aromatic hydrocarbon (PAH) and nonpolycyclic aromatic hydrocarbon (NPAH) compounds (suspected of causing cancer) are substantially reduced for biodiesel compared to diesel. Most PAH compounds can be reduced by 75% to 85%. All NPAH compounds can be reduced by at least 90%.

The health effects testing results provide conclusive scientific evidence using the most sophisticated technology available to validate the existing body of testing data. The comprehensive body of biodiesel data serves to demon-strate the significant benefits of biodiesel to the environment and to public health. This will lead to increased consumer confidence and increased use of biodiesel. Since the majority of biodiesel is made from soybean oil, a promising new market is materializing for soybeans (Anonymous 2011).

1.5.6 agriculturalimpacts

When biodiesel is made from organic oilseed crops, it helps the farming community. Because the oil used to make biodiesel is domestically grown, it keeps the money flowing to those that grow the feedstock. This continues to help out the renewable aspect of biodiesel because more seed crops can be grown by local farmers. More areas can be under cultivation and even wastelands can be cultivable with a little struggle. Nonsignificant cultural inputs like irrigation, well ploughed land, fertil-izers, hoeing, etc., are required to grow such crops. This helps to reduce soil erosion and other land problems in our country.

The smartest technologies deliver benefits to multiple interests, including an improved economy, and a positive impact on the environment and governmental poli-cies. The role of the biodiesel industry is not to replace petroleum diesel, but rather to help create a balanced energy policy with the most benefit to the United States. Biodiesel


is one of several alternative fuels designed to extend the usefulness of petroleum and the longevity and cleanliness of diesel engines. The ultimate goal is to contribute to build-ing a stronger, more self-sufficient community by way of a community-based biodiesel production model. A community-based biodiesel distribution program benefits local economies, from the farmers growing the feedstock to local businesses producing and distributing the fuel to the end consumer. The money stays in the community while reducing impact on the local environment and increasing energy security.

Since biodiesel is a fuel that can be created from locally available resources, its production and use can provide a host of economic benefits for local communities. The community-based model of biodiesel production is particularly beneficial. In this model, locally available feedstocks are collected, converted to biodiesel, and then distributed and used within the community. This model keeps energy dollars in the community instead of sending them to foreign oil producers and refineries outside the community. The peripheral benefits of this type of model are different for each case, but can include

Increased tax base from biodiesel production operations Jobs created for feedstock farming and/or collection Skilled jobs created for biodiesel production and distribution Income for local feedstock producers and refiners

Biodiesel feedstock can come from a variety of agricultural crops. When these crops are grown in a sustainable manner, using good stewardship practices, there are long-term benefits to farmers, farming communities, and the land. Many crops that yield oils used for biodiesel production can be a beneficial rotation for other food crops, including soybeans, when used in a traditional corn rotation, and canola, when used in a wheat rotation. Using crops in rotation can improve soil health and reduce erosion. The overall impacts of growing energy crops are complex, with thousands of variables. However, the added value created for oilseed crops by the production of biodiesel is a tangible benefit for farming communities and, when coupled with sustainable farming practices, can provide benefits to farming communities and the environment.

Increased utilization of renewable biofuels results in significant microeconomic benefits to both the urban and rural sectors as well as the balance of trade. Since there are multiple feedstocks from which to make biodiesel, plant operators can opt for the least expensive feedstock currently available if they have a multiple-feed-stock system. This flexibility makes producers less subject to price fluctuations. One example of this is noted by the prices of soybean oil. A study completed in 2001 by the U.S. Department of Agriculture found that an average annual increase equiva-lent to 200 million gallons of soy-based biodiesel demand would boost total crop cash receipts by $5.2 billion cumulatively by 2010, resulting in an average net farm income increase of $300 million per year. The price for a bushel of soybeans would increase by an average of 17 cents annually during the ten-year period.

Ultimately, this creates multiple beneficiaries of the production of biodiesel. By virtue of a successful market and feedstock flexibility, plant operators and farmers can both continue to operate in a marketplace with increases in revenue projected to bring $24 billion to the United States by 2015. There are many studies on the impact


of biodiesel crops on agricultural land versus food crops. The data revealed that biodiesel crops can be cultivated on marginal and wasteland rather than agricultural land. In order to reduce the risk of food and land competition, researchers through-out the world prefer mass cultivation of indigenous, nonedible oil-yielding plants on wastelands, saline soils, water-logged soils, barren land, roadsides, and along rail-way tracts (Ahmad et al. 2011).

1.5.7 biodiEsElandEnErgysEcurity

When biodiesel is used in place of petrodiesel, it reduces the amount of crude oil used up. This means that it helps to reduce our dependence on limited resources and increases the use of renewable resources. We think that this is a great step toward reducing our dependence on a fuel that may not be around forever. One of the main drivers for adoption of biodiesel is energy security. This means that a nations depen-dence on oil is reduced and substituted with use of locally available sources, such as coal, gas, or renewable sources. Given these facts and the growing uncertainty sur-rounding nations oil imports, biodiesel and other renewable fuels have an important role to play in strengthening our nations energy security. They can not only help stretch existing petroleum supplies, but can also help free nations from the hold of imported oil. Thus, a country can benefit from adoption of biofuels without a reduc-tion in greenhouse gas emissions.

While the total energy balance is debated, it is clear that the dependence on oil is reduced. One example is the energy used to manufacture fertilizers, which could come from a variety of sources other than petroleum. The US National Renewable Energy Laboratory (NREL) states that energy security is the number one driving force behind the US biofuels program, and a White House Energy Security for the 21st Century paper makes it clear that energy security is a major reason for promot-ing biodiesel. Speaking at a recent EU biofuels conference, EU commission presi-dent Jose Manuel Barroso stressed that properly managed biofuels have the potential to reinforce the EUs security of supply through diversification of energy sources (Sheehan et al. 1998).

The energy balance of a fuel is a ratio of how much energy is required to produce, refine, and distribute the fuel compared to the amount of energy the fuel releases when it is burned. This property is used to determine how renewable a fuel is. A higher ratio indicates a lower environmental impact, as less fossil energy is needed to produce, refine, and distribute the fuel.

Biodiesel has a very high energy balance compared to other alternative fuels. A joint study found that, on average, biodiesel releases 3.2 units of energy for every one unit of fossil fuel energy used to produce it. For comparison, diesel fuel deliv-ers only 0.83 units of energy for every unit of fossil fuel energy used to produce it. Worldwide, energy security is becoming a hot topic in government and society. Nearly every country in the world depends on imports of various forms of fossil fuel energy, including oil, coal, and natural gas. Without a steady supply of affordable energy, a countrys economy grinds to a halt, with no fuel for transportation, energy to run power plants and factories, or heat homes. Biodiesel can improve energy secu-rity wherever it is produced in several ways:


Domestic energy crops. When crops used to produce biodiesel are grown in the country in which the fuel is consumed, each gallon of biodiesel dis-places a gallon of imported crude oil, reducing a countrys dependence on foreign oil supplies.

Increased refining capacity. Biodiesel is produced in dedicated refineries, which add to overall domestic refining capacity, eliminating the need to import expensive finished products from other countries.

1.5.8 tEcHnicalimpacts

US government studies have shown that, in some cases, large fleets using biodiesel have been able to go longer between oil changes because the oil stays cleaner when biodiesel is used. Vehicles have similar horsepower and torque as conventional diesel when running on biodiesel. Chemically speaking, biodiesel has a higher cetane num-ber, but slightly lower energy content than diesel. To the average driver, this means better engine performance and lubrication, but a small decrease in fuel economy (2%8%). Biodiesel vehicles can also have problems starting at very cold tempera-tures, but this is more of an issue for higher percentage blends such as B100 and easily solved the same way as with conventionally fueled vehiclesby using engine block or fuel filter heaters or storing the vehicles in a building.

Many alternative fuels have difficulty gaining acceptance because they do not pro-vide similar performance to their petroleum counterparts. Pure biodiesel and biodie-sel blended with petroleum diesel fuel provide very similar horsepower, torque, and fuel mileage compared to petroleum diesel fuel. In its pure form, typical biodiesel will have an energy content 5%10% lower than typical petroleum diesel. However, it should be noted that petroleum diesel fuel energy content can vary as much as 15% from one supplier to the next. The lower energy content of biodiesel translates into slightly reduced performance when biodiesel is used in 100% form, although users typically report little noticeable change in mileage or performance. When blended with petroleum diesel at B20 levels, there is less than 2% change in fuel energy content, with users typically reporting no noticeable change in mileage or economy.

The injection system of many diesel engines relies on the fuel to lubricate its parts. The degree to which fuel provides proper lubrication is its lubricity. Low-lubricity petroleum diesel fuel can cause premature failure of injection system com-ponents and decreased performance. Biodiesel provides excellent lubricity to the fuel injection system. Recently, with the introduction of low sulfur and ultralow sulfur diesel fuel, many of the compounds that previously provided lubricating properties to petrodiesel fuel have been removed. By blending biodiesel in amounts as little as 5%, the lubricity of ultralow sulfur diesel can be dramatically improved and the life of an engines fuel injection system extended.

Diesel engines have long had a reputation of being dirty engines. However, with the advent of newer diesel engines equipped with exhaust gas recirculation (EGR), particulate filters, and catalytic converters, clean diesel technology provides incredible fuel efficiency with ultralow emissions levels. When coupled with the use of biodiesel, both new and old diesel engines can significantly reduce emissions, including particulate matter (black smoke).

11

2 Biodiesel Production2.1 GLOBALBIODIESELSOURCES

Many resources can be used as raw material for biodiesel production. These resources mainly originated from plants, particularly, and animals, in general. Depending upon the availability and production, the raw material for biodiesel can be classified into three main headings: oil-yielding plants, animal fats, and recycled cooking oil. The raw material used for biodiesel production can be

Vegetable oils Waste vegetable oil (WVO) Algae Cow dung Beef tallow Pork lard Trap grease Microorganisms (geobacters) Wild trees Wastewater by bacteria UFOs (used frying oils)

Alternative diesel fuels are made from natural, renewable sources such as veg-etable oil and animal fats (Ratledge 1985; Lee, Johnson, and Hammond 1995). More than 350 oil-bearing crops have been identified, among which only soybean, palm, sunflower, safflower, cottonseed, rapeseed, pongame, castor bean, and peanut oils are considered as potential alternative fuels for diesel engines (Goering et al. 1982).

Vegetable oils are promising feedstock for biodiesel production since they are renewable in nature, can be produced on a large scale, and are environmentally friendly (Patil and Deng 2009). Vegetable oils include edible and nonedible oils. More than 95% of biodiesel production feedstock comes from edible oils since they are mainly produced in many regions and the properties of biodiesel produced from these oils is suitable to be used as diesel fuel substitute (Gui, Lee, and Bhatia 2008). However, this may cause some problems, such as competition with the edible oil market, which increases the cost of both edible oils and biodiesel (Kansedo, Lee, and Bhatia 2009).

In order to overcome these disadvantages, many researchers are interested in nonedible oils, which are not suitable for human consumption because of the pres-ence of some toxic components in the oil. Nonedible oil crops can be grown in waste-lands that are not suitable for food crops, and the cost of cultivation is much lower because these crops can still sustain reasonably high yield without intensive care (Kumar and Raheman 2007; Gui et al. 2008). Animal fats contain higher levels of


saturated fatty acids; therefore, they are solid at room temperature, which may cause problems in the production process. The cost is also higher than that of vegetable oils (Singh and Singh 2009).

The source of biodiesel usually depends on the crops amenable to the regional climate. In the United States, soybean oil is the most common biodiesel feedstock, whereas rapeseed (canola) oil and palm oil are the most common source for biodiesel in Europe and in tropical countries, respectively (Knothe 2002). A suitable source to produce biodiesel should not compete with other applications that raise pricesfor example, pharmaceutical raw materials. But the demand for pharmaceutical raw material is lower than for fuel sources.

As much as possible, the biodiesel source should fulfill two requirements: low production costs and large production scale. Refined oils have high production costs, but low production scale; on the other hand, nonedible seeds, algae, and sewerage have low production costs and are more available than refined or recycled oils. The oil percentage and the yield per hectare are important parameters to consider as biodiesel sources. Algae can grow practically every place where there is enough sunshine. Some algae can grow in saline water. The most significant difference of algal oil is in the yield and hence its biodiesel yield. According to some estimates, the yield (per acre) of oil from algae is over 200 times the yield from the best performing plant/vegetable oils (Sheehan et al. 1998).

2.2 CHEMISTRYOFOILANDBIODIESEL

From a chemical point of view, oils from different sources have different fatty acid compositions. The fatty acids vary in their carbon chain length and in the num-ber of unsaturated bonds they contain. Fats and oils are primarily water-insoluble, hydrophobic substances in the plant and animal kingdom that are made up of 1 mol of glycerol and 3 mol of fatty acids and are commonly referred as triglycerides (Sonntag 1979).

Chemically, the oils and fats consist of 90%98% triglycerides and small amounts of mono- and diglycerides. Triglycerides are esters of three fatty acids and one glyc-erol. These contain substantial amounts of oxygen in their structures. When three fatty acids are identical, the product is simple triglycerides; when they are dissimilar, the product is mixed triglyceride fatty acids, which are fully saturated with hydrogen and have no double bonds. Those with one missing hydrogen molecule have one double bond between carbon atoms and are called monosaturated. Those with more than one missing hydrogen have more than one double bond and are called polyun-saturated. Fully saturated triglycerides lead to excessive carbon deposits in engines. The fatty acids are different in relation to the chain length, degree of unsaturation, or presence of other chemical functions.

Chemically, biodiesel consists of alkyl (usually methyl) esters instead of the alkanes and aromatic hydrocarbons of petroleum-derived diesel. Oil, ester, and diesel have different numbers of carbon and hydrogen compounds. Diesel has no oxygen compound. It is a good quality of fuel. On the other hand, in the case of veg-etable oils, oxidation resistance is markedly affected by the fatty acid composition. The large size of vegetable oil molecules (typically three or more times larger than

13Biodiesel Production

hydrocarbon fuel molecules) and the presence of oxygen in the molecules suggest that some fuel properties of oil would differ markedly from those of hydrocarbon fuels (Goering et al. 1982).

Petroleum-based diesel fuels contain only carbon and hydrogen atoms, which are arranged in normal (straight chain) or branched chain structures, as well as aro-matics configuration. The normal structures are preferred for better ignition qual-ity (Kapur, Bhasin, and Mathur 1982). Diesel fuel can contain both saturated and unsaturated hydrocarbons, but the latter are not present in large enough amounts to cause fuel oxidation problems. Petroleum-derived diesel is composed of about 75% saturated hydrocarbons (primarily paraffins, including n-, iso-, and cycloparaf-fins), and 25% aromatic hydrocarbons (including naphthalenes and alkylbenzenes) (ATSDR 1995). The average chemical formula for common diesel fuel is C12H23, ranging from approximately C10H20 to C15H28.

Vegetable oils contain fatty acid, free fatty acids (FFAs; generally, 1%5%), phospholipids, phosphatides, carotenes, tocopherols, sulfur compound, and traces of water (Markley 1960). Triglyceride molecules have molecular weights between 800 and 900 and are thus nearly four times larger than typical diesel fuel molecules (Goering 1988). The various vegetable oils and esters are distinguished by their fatty acid compositions.

An understanding of plant-based biodiesel chemistry requires an understanding of the chemical makeup of its parent material, vegetable oil. Fats and oils contain a glycerol molecule (a type of alcohol) bonded to three fatty acid chains. This struc-ture is commonly called a triglyceride. In the biodiesel manufacturing process, the fatty acids are separated from the glycerol to create free fatty acids, which are then bonded to either methyl or ethyl alcohol, depending on which is used in the manu-facturing process.

Different fats or oils contain different types of fatty acid chains. These chains dif-fer in the number of carbon atoms and the number of carboncarbon double bonds in the chain. In Table2.1, these fatty acid chains are designated by both the number of carbon atoms and the number of double bonds (e.g., 18:1 indicates 18 carbon atoms and one double bond). In soybean oil, for example, there are four types of chains that contain 18 carbon atoms:

8% with 16 carbon atoms (palmitic acid)3% with 18 carbon atoms (stearic acid)25% with 18 carbon atoms and one double bond (oleic acid)55% with 18 carbon atoms and two double bonds (linoleic acid)8% with 18 carbon atoms and three double bonds (linolenic acid)

A double bond normally introduces a kink in the chain. These double bonds play an important part in the stability of biodiesel. Note that vegetable oils and biodiesel are not hydrocarbons because oxygen atoms are present in their structure, while gas-oline and petrodiesel are true hydrocarbons, made up only of molecules of hydrogen and carbon. The bulk of a typical gasoline consists of molecules with between 5 and 12 carbon atoms. Most plant-derived fatty acids are eight or more carbons in length and have an even number of carbon atoms because of their biosynthesis process.

14Practical H

and

bo

ok o

n B

iod

iesel Prod

uctio

n an

d Pro

perties

TABLE2.1ComparativeFuelSpecificationofBiodiesel

BiodieselStandards Europe Germany UnitedStates PetroleumDiesel

Specification EN 14214:2003 DIN V 51606 ASTM D 6751-07b EN 590:1999

Applies to FAME FAME FAAE Diesel

Density 15C g/cm 0.860.90 0.8750.90 0.820.845

Viscosity 40C mm/s 3.55.0 3.55.0 1.96.0 2.04.5

Distillation % @ C 90%, 360C 85%, 350C95%, 360C

Flashpoint (Fp) C 120 min 110 min 93 min 55 min

CFPP C Country specific Summer 0; spr./aut. 10; winter 20 Country specific

Cloud point C Report

Sulfur mg/kg 10 max 10 max 15 max 350 max

CCR 100% % mass 0.05 max 0.05 max

Carbon residue (10% dist. residue) % mass 0.3 max 0.3 max 0.3 max

Sulfated ash % mass 0.02 max 0.03 max 0.02 max

Oxide ash % mass 0.1 max

Water mg/kg 500 max 300 max 500 max 200 max

Total contamination mg/kg 24 max 20 max 24 max

Cu corrosion max 3 h/50C 1 1 3 1

Oxidation stability h; 110C 6 h, min 3 h, min N/A (25 g/m3)

15B

iod

iesel Prod

uctio

n

Cetane number 51 min 49 min 47 min 51 min

Acid value mg KOH/g 0.5 max 0.5 max 0.5 max

Methanol % mass 0.20 max 0.3 max 0.2 max or Fp < 130C

Ester content % mass 96.5 min

Monoglyceride % mass 0.8 max 0.8 max

Diglyceride % mass 0.2 max 0.4 max

Triglyceride % mass 0.2 max 0.4 max

Free glycerol % mass 0.02 max 0.02 max 0.02 max

Total glycerol % mass 0.25 max 0.25 max 0.24 max

Iodine value 120 max 115 max

Linolenic acid ME % mass 12 max

C (x:4) and greater unsaturated esters % mass 1 max

Phosphorus mg/kg 10 max 10 max 10 max

Alkalinity mg/kg 5 max

Gp I metals (Na, K) mg/kg 5 max 5 max

Gp II metals (Ca, Mg) mg/kg 5 max 5 max

PAHs % mass 11 max

Lubricity/wear m at 60C 460 max

Source: http://www.biofuelsystems.com/specification.htm


Most liquid plant oils (soybean, canola, safflower, sunflower, etc.) are composed of predominantly 18-carbon fatty acids. Longer chain fatty acids, such as those found in camelina, mustard, and meadow foam, give these oils unique hydrating and stabil-ity properties.

Carbon chain length and double bonds affect the chemical behavior of fats and oils. Fats, which tend to be solid at room temperature, often have shorter carbon fatty acids and tend to have fewer double bonds. This results in straighter chains, allowing for the packing that a solid requires. Oils, which tend to be a liquid at room tem-perature, tend to have more double bonds, with corresponding kinks in their fatty acid chains leading to a liquid state. It is possible to hydrogenate an oil to remove double bonds and make it more solid at room temperature. The opposite is also possible.

Biodiesel produced from different source oils will contain different proportions and types of fatty acid chains. This is why biodiesel produced from soybean oil will not have the identical chemical properties of biodiesel produced from canola oil. For example, soybean oil has a melting point of 16C while canola oil melts at 10C. Palm oil (an oil with 45% C16 palmitic acid) melts at 35C. Melting point and oxida-tive stability are the concerns in regard to biodiesel. For example, palm oil will be in the form of a sludge or solid at temperatures common in Oregon in winter, and this makes it more difficult to deal with in a factory setting than for liquids.

Fatty acids that have no double bonds are termed saturated. These chains con-tain the maximum number possible of hydrogen atoms per carbon atom. Stearic acid is saturated. Fatty acids that have double bonds are unsaturated. These chains do not contain the maximum number of hydrogen atoms possible due to the double bonds present on some carbon atoms. Linoleic acid is unsaturated. One double bond is termed monounsaturated, and more than one double bond is termed polyun-saturated. The location and number of double bonds are important because they influence reactions that can occur to destabilize the fatty acid chain.

The interaction of oxygen molecules with the fatty acid chain, called oxida-tion, is the chemical mechanism that destabilizes oil/biodiesel. The relative oxida-tion rates of linoleic and linolenic fatty acids compared to oleic acid are 27 times as much and 77 times as much, respectively. After oxidation, hydroperoxides (one hydrogen atom and two oxygen atoms) are attached to the fatty acid chain. In a food oil, this leads to rancidity. In biodiesel, these degraded chains can polymerize, hooking together into various substances, including insoluble gums that clog up parts. Iodine number/value and oil stability index (OSI) are different measures of oil or biodiesel stability.

To be used as a motor fuel, any biodiesel will have to meet ASTM (American Society for Testing and Materials) standards. If a vegetable oil can be manipulated, processed, or combined with additives so that it meets ASTM standards, then the fuel will have access to the marketplace. This means, for example, that a biodiesel from palm oil will require manipulation or additives to address its melting point concerns, but that it may be possible to meet ASTM standards. These processes, however, can add significant costs. In the case of petroleum fuel, this is an extremely complex mixture of hydrocarbon compounds, usually with minor amounts of nitro-gen-, oxygen-, and sulfur-containing compounds as well as trace amounts of metal-containing compounds (Speight 2007).


2.3 OILEXTRACTION

H

CCCC

HH

H

HHH

HH

HHH CCH

Unsaturated Fatty Acids

Saturated Fatty Acids

Glycerol

Triglyceride

Glycerine - propane 1,2,3, triol-3 hydroxyl (OH) functional group)

Fatty Acids

C

H

CCCCCO

O

HH

H

HHH

HH

HH CC

H

HH

C H

C

H

H

H

CCCCCO

O

HH

H

HHH

HH

HH CC

H

HH

C H

C

H

HH

HCCCC

HH

H

HHH

HH

HH CC

H

H

C H

C

CH

CH2

CH2

O

O

O

O

H

OH

H HC

H

OH

C

H

OH

C

C

C

R

R

R

O

O

Various techniques and methods have been developed to extract the oils and process them to finished products (see Figure2.1). The common objective of all these pro-cesses is to

Maximize the yield of fat or oil from the oil-bearing material Minimize the damage to the fat or oil and solid fraction Produce components as free as possible from undesirable impurities Produce a residual oil cake of the greatest possible value

In many parts of the world, commercial hydraulic presses (Figure2.2) are the most practical and economical way to extract oil from seeds. They may be powered by hand or by electricity. Ground seed material or wet plant tissue is placed in the


press in layers, with each layer separated from the next by a press cloth. Pressure is appliedslowly at first and then increased as the oil content in the tissue decreases. Maximum total pressure is 13,970 kPa for 1 inch layers. Total time to load, apply pressure, and remove cake is approximately 1 h. Drainage of the oil while under

Vegetable Oils

Methanol + NaOH

MethanolRecovery

Glycerin Soap

Refining Refining

Biodiesel

Crude Glycerin Crude Soap Crude Biodiesel

GlycerinRefining

Transesterification

FIGURE2.1 Biodiesel preparation flow sheet.

FIGURE2.2 Oil extraction by conventional method.


pressure may require 3045 min. The advantages of the commercial size batch press are that it can be driven by hand or electricity, is simple and economical to operate and maintain, requires minimum operator training, and provides an excellent oil recovery. Disadvantages include the substantial cost of the machinery, long delivery times, difficulty in obtaining spare parts in remote areas, and the necessity of electric power to operate larger models.

Continuous screw presses, or expellers (Figure2.3), are used in higher technol-ogy areas throughout the world for the expulsion of oil from rapeseeds, canola, castor beans, sunflower seeds, and other varieties of seed where there is sufficient seed supply to justify a continuous operation. Sufficient pressure is achieved by means of an auger that turns inside a barrel. The barrel is closed, except for depart-ing pressed cake.

Expellers exert much greater pressure on seed cake than that produced by a hydraulic batch press. This increased pressure results in a greater recovery of the oil content in the feedstock. Expellers can vary in size from units that process 40 kg of conditioned seed per hour (Figure2.4) to machines that process 200 tons of seed per hour. Expellers are an essential part of most modern oilseed extraction plants that employ a prepress step in the oil extraction process. Expellers have a higher plant capacity and a higher rate of oil recovery with a lower labor requirement than the press system. Disadvantages of the expeller system include the requirement for electric power, continuous operation, and the need for skilled mechanics. Equipment and maintenance costs are also high. The oil produced contains more impurities and must be heated and filtered for biodiesel production.

2.4 COMMERCIALOILEXTRACTION

Currently, three types of commercial processing systems are employed for oilseeds in the higher technology sector of the world:

FIGURE2.3 Electric oil expeller.


Expeller pressing: oil is mechanically squeezed from the seed. Solvent extraction: a portion of the oil is removed by expellers and the

remainder can be extracted with an organic solvent. Direct solvent extraction: the oil is removed directly from the conditioned

seed with an organic solvent.

The first step in the total operation is to crush the oilseeds and separate the oil cakes and crude oil. Crude oil may then have the hydratable gums removed by using a water degumming process or have most of the gums taken out by an acid degumming operation. Crude or degummed oils may then be conditioned with phosphoric acid and treated with sodium hydroxide in a continuous centrifugal alkali refining operation. The refined oil is bleached with activated clay to remove color pigments.

Hydrogenation is an optional process used to adjust the consistency of fats and oils according to the physical properties required by the final products. The type of extraction system used to separate the oils from the solid fraction of an oilseed depends primarily on the oil content of the raw material. Mechanical pressing is generally used for materials exceeding 20% oil content. Oilseeds and nuts with rela-tively high oil content are usually processed by mechanical presses.

2.5 BIODIESELSYNTHESIS

Plant oils usually contain free fatty acids, phospholipids, sterols, water, odorants, and other impurities. Thus, the oil cannot be used as fuel directly. To overcome these problems, the oil requires slight chemical modificationmainly pyrolysis, micro-emulsion, dilution, and transesterification.

FIGURE2.4 A small unit lab oil expeller.


2.5.1 Pyrolysis

Pyrolysis is a method of converting one substance into another by means of heat or by heat with the aid of the catalyst in the absence of air or oxygen (Sonntag 1979). The process is simple, waste-less, pollution free, and effective compared with other cracking processes.

2.5.2 Dilution

The vegetable oil is diluted with petroleum diesel to run the engine. Caterpillar Brazil, in 1980, used precombustion chamber engines with the mixture of 10% veg-etable oil to maintain total power without any alteration or adjustment to the engine. At that point, it was not practical to substitute 100% vegetable oil for diesel fuel, but a blend of 20% vegetable oil and 80% diesel fuel was successful. Some short-term experiments used up to a 50:50 ratio.

2.5.3 MicroeMulsion

A microemulsion is defined as a colloidal equilibrium dispersion of optically isotro-pic fluid microstructure with dimensions generally in the 1150 range formed spon-taneously from two normally immiscible liquids and one or more ionic amphiphiles (Schwab et al. 1988). They can improve spray characteristics by explosive vaporiza-tion of the low boiling constituents in micelles (Pryde 1984; Ziejewski et al. 1984). The engine performances were the same for a microemulsion of 53% sunflower oil and the 25% blend of sunflower oil in diesel (Ziejewski, Kaufman, and Pratt 1983). A microemulsion prepared by blending soybean oil, methanol, and 2-octanol and cetane improver in ratios of 52.7:13.3:33.3:1.0 also passed the 200 h EMA test (Goering 1984)

2.5.4 transesterification

Transesterification or alcoholysis is the displacement of alcohol from an ester by another in a process similar to hydrolysis, except that alcohol is used instead of water. Methanol is the most common alcohol used due to its low cost and low water content (Srivastava and Prasad 2000). This process has been widely used to reduce the high viscosity of triglycerides. The transesterification reaction is represented by the following general equation:

Triglyceride Methanol (3) Glycerol Methyl Esters (3)

O

O R

+ 3 [H3C OH] + 3O O

OR

R

O OH

HO

Catalyst OH

OR

OH3C


2.5.5 Base-catalyzeDtransesterification

For an alkali-catalyzed transesterification, the glycerides and alcohol must be sub-stantially anhydrous (Wright et al. 1944) because water makes the reaction par-tially change to saponification, which produces soap. The reaction mechanism for alkali-catalyzed transesterification was formulated in three steps (Eckey 1956), as explained in Figure2.1. The first step is an attack on the carbonyl carbon atom of the triglycerides molecule by the anion of the alcohol (methoxide ion) to form a tetrahe-dral intermediate that reacts with an alcohol (methanol) to regenerate the anion of alcohol (methoxide ion). In the last step, rearrangement of a tetrahedral intermediate results in the formation of a fatty acid ester and a diglyceride. When NaOH, KOH, K2CO3, or other similar catalysts are mixed with alcohol, the actual catalyst, alk-oxide group is formed. Kim et al. (2004) developed a process for the production of biodiesel from vegetable oils using heterogeneous catalyst Na/NaOH/Al2O3.

Transesterification is one of the reversible reactions and proceeds essentially by mixing the reactants. However, the presence of a catalyst (a strong acid or base) accelerates the conversion. Transesterification of triglycerides produces fatty acid alkyl esters and glycerol. The glycerol layer settles down at the bottom of the reac-tion vessel. Diglycerides and monoglycerides are the intermediates in this process.

The stepwise reactions are reversible and a little excess of alcohol is used to shift the equilibrium toward the formation of esters. In the presence of excess alcohol, the foreword reaction is pseudo-first order and the reverse reaction is found to be second order. It was also observed that transesterification is faster when catalyzed by alkali (Freedman, Butterfield, and Pryde 1986).

2.5.6 aciD-catalyzeDtransesterification

An alternative process is to use acid catalysts, which some researchers have claimed are more tolerant of free fatty acids (Freedman and Pryde 1982; Aksoy et al. 1988; Liu 1994). The mechanism of acid-catalyzed transesterification of vegetable oil (for a monoglyceride) is shown in Figure2.5. It can also be extended to di- and triglyc-erides. The protonation of the carbonyl group of the ester leads to the carbocation, which after a nucleophilic attack of the alcohol, produces a tetrahedral intermediate. This intermediate eliminates glycerol to form a new ester and to regenerate the cata-lyst. We can use acid alkali and biocatalyst in transesterification methods. If more water and free fatty acids are in triglycerides, an acid catalyst can be used (Keim 1945). Transmethylation occurs approximately 4,000 times faster in the presence of an alkali catalyst than in those catalyzed by the same amount of acidic catalyst (Formo 1954).

Transesterification can be catalyzed by Brownsted acids, preferably by sulfonic and sulfuric acids. These catalysts give very high yields in alkyl esters, but these reactions are slow, typically requiring temperatures above 100C and more than 3 h to complete the conversion (Schuchardt et al. 1998). The protonation of the carbonyl group of the ester leads to the carbocation, which after a nucleophilic attack of the alcohol, produces a tetrahedral intermediate. This intermediate eliminates glycerol to form a new ester and to regenerate the catalyst.


At a reaction temperature of 65C, the conversion is observed to be completed in 20 h, while butanolysis at 117C and ethanolysis at 78C, using the same quanti-ties of catalyst and alcohol, take 3 and 18 h, respectively (Freedman et al. 1986). Commercial production of biodiesel based on a systematic approach includes culti-vation of raw material (seeds), collection and harvesting of oilseeds, oil extraction, biodiesel processing techniques (transesterification: oil filtration, heating, mixing of catalysts, settling, separation, by-products, washing, and storage), biodiesel blends, fuel properties and physiochemical characterization, and implementation in engines, vehicles, or generators in terms of efficiency consumption and performance.

2.5.7 liPase-catalyzeDtransesterification

This transesterification process is like alkali transesterification, except that the ratio of catalyst and solvent stirring time is different and, in this transesterification, we have used lipase catalyst. The process is explained in Figure2.6. Lipases are known to have a propensity to act on long-chain fatty alcohols better than on short-chain ones (Shimada et al. 1998). Thus, in general, the efficiency of the transesterification of triglycerides with methanol (methanolysis) is likely to be very low compared to that with ethanol in systems with or without a solvent.

Linko et al. (1998) have demonstrated the production of a variety of biodegrad-able esters and polyesters with lipase as the biocatalyst. In the transesterification of rapeseed oil with 2-ethyl-I-hexanol, 97% conversions of esters was obtained using Candida rugosa lipase powder. De, Bhattacharyya, and Band (1999) investigated the conversion of fatty alcohol esters (C4C18:1) using immobilized Rhizomucor miehei lipase (lipozyme IM-20) in a solvent-free system. The percentage of molar conver-sions of all corresponding alcohol esters ranged from 86.8% to 99.2%, while the slip melting points of the esters were found to increase steadily with increasing alcohol chain length (from C4 to C18).

FIGURE2.5 Oil filtration.


Transesterification of the triglycerides sunflower oil, fish oil, and grease with eth-anol (i.e., ethanolysis) has also been studied. In each case, high yields beyond 80% could be achieved using the lipases from Mucor miehei (Selmi and Thomas 1998), Candida antarctica (Breivik, Haraldsson, and Kristinsson 1997), and Pseudomonas cepacia (Wu et al. 1999).

Nelson, Foglia, and Marmer (1996) investigated the abilities of lipases in trans-esterification with short-chain alcohols to give alkyl esters. The lipase from M. miehei was the most efficient for converting triglycerides to their alkyl esters with primary alcohols, whereas that from C. antarctica was the most efficient for transesterify-ing triglycerides with secondary alcohols to give branched alkyl esters. Mittelbach (1990) reported transesterification using the primary alcohols methanol, ethanol, and 1-butanol, with and without petroleum ether as a solvent.

Abigor et al. (2000) also found that in the conversion of palm kernel oil to alkyl esters using Pseudomonas cepacia lipase, ethanol gave the highest conversion of 72%, while only 15% methyl esters was obtained with methanol. Lipases are known to have a propensity to act on long-chain fatty alcohols better than on short-chain ones. Thus, in general, the efficiency of the transesterification of triglycerides with methanol (methanolysis) is likely to be very low compared to that with ethanol in sys-tems with or without a solvent.The first step involves the attack of the alkoxide ion to the carbonyl carbon of the triglyceride molecule, which results in the formation of a tetrahedral intermediate. The reaction of this intermediate with an alcohol produces the alkoxide ion in the second step. In the last step, the rearrangement of the tetra-hedral intermediate gives rise to an ester and a diglyceride (Ma and Hanna 1999).

2.6 FACTORSAFFECTINGTRANSESTERIFICATIONREACTION

The process of transesterification is affected by various factors, depending upon the reaction condition used. The effects of these factors are described next.

FIGURE2.6 Heating of oil.


2.6.1 effectofffaanDMoisturecontent

The effect of FFA and moisture content strongly depends on the type of catalyst used during transesterification. The FFA and moisture content are key parameters for determining the viability of the vegetable oil transesterification process. To carry the base-catalyzed reaction to completion, a free fatty acid value lower than 3% is needed. The higher the acidity of the oil is, the smaller is the conversion efficiency. Both excess as well as insufficient amounts of catalyst may cause soap formation (Dorado et al. 2002) (Figure2.7).

Ma, Clements, and Hanna (1998) studied the transesterification of beef tallow catalyzed by NaOH in the presence of FFAs and water. Without adding FFA and water, the apparent yield of beef tallow methyl esters (BTMEs) was highest. When 0.6% of FFA was added, the apparent yield of BTME reached the lowest level (less than 5%) with any level of water added. The products were solid at room tempera-ture, similarly to the original beef tallow. When 0.9% of water was added, without addition of FFA, the apparent yield was about 17%. If the low qualities of beef tallow or vegetable oil with high FFA are used to make biodiesel fuel, they must be refined by saponification using NaOH solution to remove free fatty acids. Conversely, the acid-catalyzed process can also be used for esterification of these FFAs.

The starting materials used for base-catalyzed alcoholysis should meet cer-tain specifications. The triglycerides should have lower acid value and all material should be substantially anhydrous. The addition of more sodium hydroxide catalyst compensates for higher acidity, but the resulting soap causes an increase in viscos-ity or formation of gels that interferes in the reaction as well as with separation of glycerol (Freedman, Pryde, and Mounts 1984). When the reaction conditions do not meet these requirements, ester yields are significantly reduced. The methoxide and hydroxide of sodium or potassium should be maintained in anhydrous state. Prolonged contact with air will diminish the effectiveness of these catalysts through interaction with moisture and carbon dioxide.

FIGURE2.7 Catalyst preparation.


Biodiesel is currently made from edible oils by using methanol and alkaline cata-lyst. However, large amounts of low-cost oils and fats could be converted to biodiesel. The problem with processing these low-cost oils and fats is that they often contain large amounts of free fatty acids that cannot be converted to biodiesel using alkaline catalyst. Therefore, a two-step esterification process is required for these feedstocks.

Initially, the FFA of these can be converted to fatty acid methyl esters by an acid-catalyzed pretreatment; in the second step, transesterification is completed by using alkaline catalyst to complete the reaction (Canakci and Van Gerpen 2001). Initial process development is performed with a synthetic mixture containing 20% and 40% free fatty acid prepared by using palmitic acid. Process parameters such as molar ratio of alcohol to oil, type of alcohol, amount of acid catalyst, reaction time, and free fatty acid level are investigated to determine the best strategy for converting the free fatty acids to usable esters.

The work shows that the acid level of the high free fatty acids feedstocks could be reduced to less than 1% with a two-step pretreatment reaction. The reaction mixture is allowed to settle between steps so that the water-containing phase can be removed. The two-step pretreatment reaction is demonstrated with actual feedstocks, including yellow grease with 12% free fatty acid and brown grease with 33% free fatty acids. After reducing the acid levels of these feedstocks to less than 1%, the transesterifica-tion reaction is completed with an alkaline catalyst to produce fuel-grade biodiesel.

Turck (2002) investigated the negative influence of base-catalyzed transesterifi-cation of triglycerides containing substantial amounts of FFA. Free fatty acids react with the basic catalyst added for the reaction and give rise to soap, as a result of which, one part of the catalyst is neutralized and is therefore no longer available for transesterification. These high FFA content oils and fats are processed with an immiscible basic glycerol phase so as to neutralize the free fatty acids and cause them to pass over into the glycerol phase by means of monovalent alcohols. The triglycerides are subjected to transesterification, using a base as catalyst, to form fatty acid alkyl esters, characterized in that, after separation, the basic glycerol phase produced during transesterification of the triglycerides is used for processing the oils and fats for removal of free fatty acids.

2.6.2 effectofcatalyst

Catalysts used for the transesterification of triglycerides are classified as alkali, acid, or enzyme, among which alkali catalysts like sodium hydroxide, sodium methoxide, potassium hydroxide, and potassium methoxide are more effective (Ma and Hanna 1999). The large use of NaOH is also motivated by comparing the cost and avail-ability: It is the c

Documents

Practical Handbook on Biodiesel Production and Properties