setting national fuel quality standards · for petrol and diesel under the national fuel quality...
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SETTING NATIONAL FUEL QUALITY STANDARDS
Paper 6
National Standard for Biodiesel – Discussion Paper
Prepared by
Environment Australia
March 2003
This work was funded by the Federal Government's $2.7 billion Natural Heritage Trust and published by the Department of the Environment and Heritage. For additional copies of this document please contact the Community Information Unit on: 1800 803 772. This document is also available on the Internet from the following address: www.ea.gov.au/atmosphere/transport/biodiesel/index.html Commonwealth of Australia, 2003 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced by any process without prior written permission from the Commonwealth, available from Environment Australia. Requests and inquiries concerning reproduction and rights should be addressed to: Assistant Secretary Atmosphere and Sustainable Transport Branch Environment Australia GPO Box 787 Canberra ACT 2601 Cover photographs in this publication are copyright and may be reproduced only with the express permission of the copyright owner. Environment Australia commissioned Pacific Air & Environment Pty Ltd to prepare a technical paper on biodiesel, its use as a transport fuel, and its impact on vehicle emissions and engine operability. The technical paper has assisted in the development of this discussion paper. The views and opinions expressed in this publication do not necessarily reflect those of the Commonwealth Government or the Minister for the Environment and Heritage. While reasonable efforts have been made to ensure that the contents of this publication are factually correct, the Commonwealth does not accept responsibility for the accuracy or completeness of the contents, and shall not be liable for any loss or damage that may be occasioned directly or indirectly through the use of, or reliance on, the contents of this publication. Cover photographs supplied by BP Australia Cover designed by Fusebox Press Publication printed by CPP Instant Printing ISBN 0 642 54908 7
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FOREWORD
The development of fuel quality standards for alternative fuels, such as biodiesel, is an important part of the Government’s continuing work to improve air quality and deliver cleaner fuels. This paper represents the Commonwealth's assessment of biodiesel standards - and we welcome your feedback.
Biodiesel is a new fuel for Australia. It has been used overseas in conventional diesel transport vehicles as a fuel for some time. Biodiesel is not currently produced or used at a commercially significant level in Australia but a fuel quality standard for biodiesel is required to underpin an expected expansion of biodiesel production and use.
Transport is the most significant contributor to ambient air pollution in urban Australia, with cars and light commercial vehicles being the dominant source of transport pollutants.
The 1997 Australian Academy of Technological Sciences and Engineering report Urban Air Pollution In Australia, commissioned by Environment Australia, found that new, tighter vehicle emission standards were ‘the long-term foundation for maintaining and improving air quality’. The Prime Minister, in his 1997 statement, Safeguarding the Future: Australia’s response to Climate Change identified harmonisation with international vehicle emission standards as a goal of the Government – with a target date of 2006. The timetable for vehicle standards harmonisation was set, in May 1999, as part of the Measures for a Better Environment initiative under the New Tax System for Australia.
Commonwealth environment, greenhouse, transport and industry agencies have, therefore been working together with relevant industry sectors to improve the emissions performance of the transport fleet. The Commonwealth has already implemented new fuel quality standards for petrol and diesel under the national Fuel Quality Standards Act 2000. The Act provides the framework for the implementation of improved fuel quality, outlining the way fuel quality is specified and managed. These standards are a major achievement and contribute significantly to reduction of greenhouse gas emissions and air pollutants from Australian road transport.
Any proposal to improve, and mandate, the quality of fuels used in Australia, has the potential to impact on a wide range of stakeholders. Wide ranging stakeholder input will help achieve a fuel quality standard that meets the needs of Australian motorists and allows for optimum vehicle and environmental performance. I look forward to considering your views on the matter and urge you to make a submission. David Kemp Minister for the Environment and Heritage
TABLE OF CONTENTS
Acronyms ................................................................................................................................................x
Glossary of Terms ...............................................................................................................................xiii
1 INTRODUCTION .......................................................................................1
1.1 Objective of this paper ...............................................................................................................1
1.2 Structure of Paper ......................................................................................................................2
1.3 Call for public submissions........................................................................................................3
2 BACKGROUND.........................................................................................4
2.1 Environmental impacts of transport.........................................................................................4
2.2 Measures for a Better Environment..........................................................................................5
2.3 Fuel Quality Standards (FQS) Act............................................................................................6
2.4 Transport policy .........................................................................................................................6
2.5 Key dates .....................................................................................................................................7
2.6 Harmonisation with the European Union fuel standards .......................................................8
2.7 General principles and policy requirements ............................................................................8 2.7.1 Guiding Principles ................................................................................................................9
2.8 International biodiesel standards............................................................................................10
2.9 The case for a national biodiesel standard in Australia ........................................................11
3 BIODIESEL..............................................................................................12
3.1 Basic chemistry and terminology ............................................................................................12
3.2 Feedstocks .................................................................................................................................13
4 IMPACTS OF BIODIESEL USE ..............................................................14
4.1 Emissions...................................................................................................................................14
4.2 Toxicity ......................................................................................................................................17
4.3 Lubricity....................................................................................................................................17
4.4 Biodegradability .......................................................................................................................18
4.5 Niche markets based on the biodegradability of biodiesel ....................................................20
4.6 Energy Balance .........................................................................................................................20
4.7 Fuel economy ............................................................................................................................20
4.8 Storage, Handling and Distribution........................................................................................20 v
5 – BIODIESEL BLENDS..............................................................................22
5.1 The European Union experience .............................................................................................22
5.2 The United States experience...................................................................................................22
5.3 The Australian situation ..........................................................................................................23
6 BIODIESEL PARAMETERS....................................................................24
6.1 Sulfur .........................................................................................................................................28
6.2 Carbon Residue ........................................................................................................................29
6.3 Phosphorous..............................................................................................................................30
6.4 Ester content .............................................................................................................................31
6.5 Kinematic viscosity ...................................................................................................................32
6.6 Cetane Number.........................................................................................................................33
6.7 Sulphated Ash content..............................................................................................................34
6.8 Total contamination .................................................................................................................35
6.9 Acid value..................................................................................................................................36
6.10 Iodine number...........................................................................................................................38
6.11 Linoleic acid methyl ester and polyunsaturated methyl esters (>4 double bonds) .............39
6.12 Mono- and Di-Glycerides.........................................................................................................41
6.13 Triglyceride content .................................................................................................................42
6.14 Free Glycerol.............................................................................................................................43
6.15 Total Glycerol ...........................................................................................................................44
6.16 Alkaline metals..........................................................................................................................45
Biodiesel Parameters Affecting Stability ............................................................................................45
6.17 Thermal Stability......................................................................................................................47
6.18 Oxidation Stability....................................................................................................................47
6.19 Alcohol Content ........................................................................................................................50
6.20 Cloud Point ...............................................................................................................................51
6.21 Cold Filter Plugging Point .......................................................................................................52
6.22 Distillation Temperature..........................................................................................................53
6.23 Calorific Value ..........................................................................................................................54
Biodiesel parameters that affect other properties .............................................................................55
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6.24 Density .......................................................................................................................................55
6.25 Flash Point.................................................................................................................................56
6.26 Dissolved Water Content .........................................................................................................57
6.27 Free Water and Sediment Content .........................................................................................58
6.28 Corrosion...................................................................................................................................59
7 ALCOHOL ...............................................................................................61
7.1 Methanol and Ethanol as reagents..........................................................................................61
7.2 Alcohol properties ....................................................................................................................61
7.3 Differences between production technologies ........................................................................61
7.4 Reaction conversion..................................................................................................................62
7.5 Glycerol Content.......................................................................................................................62
7.6 Viscosity.....................................................................................................................................62
7.7 Impacts on vehicle emissions and engine operability ............................................................63
8 TECHNICAL ANALYSIS OF THE IMPACTS OF BLENDING BIODIESEL WITH DIESEL................................................................................................64
8.1 Effect on Engine Operability ...................................................................................................64 8.1.1 Ester content .......................................................................................................................64 8.1.2 Kinematic Viscosity ...........................................................................................................64 8.1.3 Cetane Number ...................................................................................................................65 8.1.4 Sulphated Ash Content .......................................................................................................65 8.1.5 Total Contaminants.............................................................................................................65 8.1.6 Acid Value..........................................................................................................................65 8.1.7 Iodine Number....................................................................................................................66 8.1.8 Linoleic Acid Methyl Ester ................................................................................................66 8.1.9 Mono- and Diglyceride Content .........................................................................................66 8.1.10 Triglyceride Content...........................................................................................................66 8.1.11 Free glycerin.......................................................................................................................66 8.1.12 Alkaline Metals...................................................................................................................67
8.2 Impacts on emissions ................................................................................................................67
9 EFFECT OF BIODIESEL ON DIESEL ENGINE OIL...............................68
9.1 Polymerisation of Vegetable Oil Derived Esters ....................................................................68 9.1.1 Initiation Phase (Induction Period) ....................................................................................68 9.1.2 Metal Catalysts ...................................................................................................................68 9.1.3 Lipoxidase – Naturally Occurring Enzyme ........................................................................69 9.1.4 Thermal Polymerisation .....................................................................................................69 9.1.5 “Rise and Fall” Viscosity Pattern .......................................................................................69 9.1.6 Antioxidant additives..........................................................................................................69
9.2 Potential Oil Degradation Factors ..........................................................................................69
10 VEHICLE WARRANTIES AND LABELLING.......................................71
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10.1 Warranties ................................................................................................................................71
10.2 The International Experience..................................................................................................71
10.3 The Australian Situation..........................................................................................................75
10.4 Australian Design Rule (ADR) Compliance ...........................................................................77
10.5 Other compliance......................................................................................................................77
10.6 Labelling....................................................................................................................................77
11 REFERENCES .....................................................................................78
APPENDIX A – FUEL QUALITY STANDARDS FOR PETROL AND DIESEL.......................................................................................................................85
Table.1 Petrol Standards ...............................................................................................................85
Table 2 Diesel Standards ...............................................................................................................86
APPENDIX B - INTERNATIONAL TRENDS IN BIODIESEL PRODUCTION AND USE.......................................................................................................87
Europe ...................................................................................................................................................87
Germany................................................................................................................................................88
Austria ...................................................................................................................................................90
France....................................................................................................................................................90
Ireland ...................................................................................................................................................90
Italy........................................................................................................................................................90
Luxembourg..........................................................................................................................................90
Portugal .................................................................................................................................................91
Sweden...................................................................................................................................................91
United States of America .....................................................................................................................91
US Market Summary ...........................................................................................................................91
APPENDIX C - BIODIESEL PRODUCTION .................................................93
Industrial scale production of biodiesel..............................................................................................94
APPENDIX D - EFFECTS OF DIFFERENT FEEDSTOCKS ON BIODIESEL FUEL PARAMETERS ...............................................................96
Content of saturated, mono-, di-, and polyunsaturated fatty acids..................................................96
Content of short-chain vs. long chain fatty acids...............................................................................98
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Summary ...............................................................................................................................................99
APPENDIX E – IMPACTS OF BIODIESEL ON DIESEL ENGINE OIL .......101
Iodine number.....................................................................................................................................101
Viscosity...............................................................................................................................................101
Oil Change Interval............................................................................................................................102
Oil Type...............................................................................................................................................102
Method of Injection (Indirect Injected vs. Direct Injected) ............................................................102
Feedstock Effect on Biodiesel ............................................................................................................102
Blend of Biodiesel Used ......................................................................................................................103
Engine Duty Cycle ..............................................................................................................................103
Oxidation Stability..............................................................................................................................103
Engine Oil Acid Value........................................................................................................................103
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Acronyms
AAT NEPM Ambient Air Toxics National Environment Protection Measure
AATSE Australian Academy of Technological Sciences and Engineering
ADR Australian Design Rule
ANZMEC Australian and New Zealand Minerals and Energy Council
AOCS American Oil Chemists Society
ASTM American Society for Testing and Materials
BSI British Standards Institution
CCI Calculated Cetane Index
CFPP Cold Filter Plugging Point
CNG Compressed Natural Gas
CO Carbon Monoxide
CO2 Carbon Dioxide
COAG Council of Australian Governments
CP Cloud Point
DIS Draft International Standard
DOE Department of Energy (US)
DSC Differential Scanning Calorimetry
EA Environment Australia
EC European Cummunity
EGR Exhaust Gas Recirculation
EPA Environmental Protection Agency (US)
EU European Union
FAME Fatty Acid Methyl Ester
FIE Fuel Injection Equipment
FP Flash Point
FQS Fuel Quality Standards (refers to the Fuel Quality Standards Act 2000)
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FSCC Fuel Standards Consultative Committee (under the Fuel Quality Standards Act 2000)
GATT General Agreement on Tariffs and Trade
GHG Greenhouse Gas Emissions
GVM Gross Vehicle Mass
GVWR Gross Vehicle Weight Rating
HDDV Heavy-duty Diesel Vehicles
HDHV Heavy-duty Highway Vehicles
HC Hydrocarbon(s)
HO High Oleic
HV Heat Value
IEA International Energy Agency
IP Institute of Petroleum
IV Iodine Value
KOH Potassium hydroxide
LPG Liquefied Petroleum Gas
LL Low Linolenic
LSD Low Sulfur Diesel
NaOH Sodium hydroxide
NBB National Biodiesel Board (US)
NEPC National Environment Protection Council
NEPM National Environment Protection Measure
NOx Oxides of Nitrogen
NPAH Nitrited Polycyclic Aromatic Hydrocarbon(s)
NREL National Renewable Energy Laboratory (US Department of Energy)
OEM Original Equipment Manufacturers
PAH Polycyclic Aromatic Hydrocarbon(s)
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PM Particulate Matter
PME Plant Methyl Ester
PP Pour Point
ppm parts per million
PV Peroxide Value
RIS Regulation Impact Statement
RME/RSME Rapeseed Methyl Ester
SAE Society of Automotive Engineers
SoE State of the Environment
SOME Soybean Oil Methyl Ester
TAN Total Acid Number
TBN Total Base Number
UFOP Union for the Promotion of Oil and Protein Plants
ULSD Ultra Low Sulfur Diesel
UN ECE United Nations Economic Commission for Europe
US United States of America
USDA United Stated Department of Agriculture
VOME Vegetable Oil Methyl Ester
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Glossary of Terms
ASTM D 6751-02
Standard Specification for Biodiesel Fuel (B100) Blend Stock for Distillate Fuels.
ASTM D 975-02
Standard Specification for Diesel Fuel Oils.
AS 3570-1998
Australian Standard – Automotive diesel fuel.
BIOSTAB
Stability of Biodiesel project funded by the European Community, started in 2001.
BLT Austria
Bundesanstalt fur Landtechnik – Federal Institute of Agricultural Engineering, Austria.
BXX
B100 is neat biodiesel. Biodiesel blended with petroleum-based diesel fuel is referred to as a biodiesel blend; for example, B5 is a 5% biodiesel and 95% petroleum-based diesel blend.
CEN
European Committee for Standardisation.
Cetane Number
A measure of the ignition quality of diesel fuel based on ignition delay in an engine. The higher the cetane number the shorter the ignition delay and the better the ignition quality. The cetane number is based on the ignition quality of cetane (C16H34) and heptamethylnonane.
DIN
The German Institute for Standardisation.
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DIN 51606
German FAME standard.
DGF
Test Methods of Deutsche Gesellschaft für Fettwissenschaft e.V. Münster i W.
EN 590
CEN standard for diesel.
Exbodied Emissions
Emissions associated with the cumulative life-cycle of the fuel including its combustion.
Heavy Duty Diesel Vehicles
Vehicles >3.5 tonnes GVM.
HDHV
Heavy-duty Highway Vehicles, defined by US Federal vehicle weight definitions as being greater than 8,500 pounds GVWR.
ISO
International organisation for standardisation.
Light Duty Diesel Vehicles
Vehicles <3.5 tonnes GVM.
LSD
Low Sulfur Diesel – diesel fuel with < 500ppm sulfur content (Australian context).
Lubricity
The ability to reduce friction between solid surfaces in relative motion.
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Non-glyceridic neutral lipids
Include free fatty acids, fatty alcohols, hydrocarbons, sterols, triterpene alcohols, carotinoids, and vitamins. Their distribution depends on the feedstock oil used.
PAH
Polycyclic Aromatic Hydrocarbon(s). Aromatics of which the molecules contain several, linked benzene rings; in several cases carcinogenic.
prEN 14214
Draft CEN standard for FAME for diesel engines.
Total Acid Number (TAN)
Is an indication of the presence of free fatty acids or acids formed due to oil degradation and combustion (during or following processing).
Total Base Number (TBN)
Indicates the ability of the lubricant to neutralise acid compounds generated by combustion and degradation of the oil (also termed the alkaline number).
ULSD
Ultra Low Sulfur Diesel – diesel fuel with <50ppm sulfur content (Australian context).
Unsaponifiable matter
The non-glyceridic neutral lipids, which are insoluble in water after saponification of the fat.
US diesel classifications
Grade Low Sulfur No. 1-D—A special-purpose, light distillate fuel for automotive diesel engines requiring low sulfur fuel and requiring higher volatility than that provided by Grade Low Sulfur No. 2-D.
Grade Low Sulfur No. 2-D— A general-purpose, middle distillate fuel for automotive diesel engines requiring low sulfur fuel. It is also suitable for use in non-automotive applications, especially in conditions of varying speed and load.
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Grade No. 1-D—A special-purpose, light distillate fuel for automotive diesel engines in applications requiring higher volatility than that provided by Grade No. 2-D fuels.
Grade No. 2-D—A general-purpose, middle distillate fuel for automotive diesel engines, which is also suitable for use in non-automotive applications, especially in conditions of frequently varying speed and load.
Grade No. 4-D—A heavy distillate fuel, or a blend of distillate and residual oil, for low- and medium-speed diesel engines in non-automotive applications involving predominantly constant speed and load.
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1 INTRODUCTION Biodiesel is a renewable fuel derived from vegetable oils or animal fats through the process of esterification. Biodiesel is used in conventional diesel engines. There is a growing amount of experience internationally in the use of biodiesel as a transport fuel. Unlike the process of setting fuel quality standards for petrol or diesel, there is currently no uniform industry accepted biodiesel standard in Australia. There are currently no State/Territory based fuel quality standards for biodiesel. There are however examples of quality standards for biodiesel internationally and these will be compared and discussed. Under the Fuel Quality Standards Act 2000 biodiesel is listed as a fuel for which standards can be made. The technical issues presented in this paper have been identified by Environment Australia as being important with regard to biodiesel fuel quality. Environment Australia commissioned Pacific Air & Environment Pty Ltd to prepare a technical paper on biodiesel, its use as a transport fuel, and its impact on vehicle emissions and engine operability. The technical paper has assisted in the development of this discussion paper.
1.1 Objective of this paper The objective of this paper is to inform stakeholders and generate comment on setting a standard for biodiesel. The Commonwealth aims to set fuel quality standards that allow for optimum vehicle and environmental performance. Informed public debate is necessary to ascertain how quality standards are best managed. This involves decisions relating to both the level at which they are managed (nationally or at the State/Territory level) and the specifications that are set for each parameter within the standard. In evaluating outcomes, consideration needs to be given to a diverse range of policy objectives, as in many instances compromises and trade-offs may be necessary between differing requirements. This is as likely between common interests (such as reducing both noxious and greenhouse emissions), as between competing interests (such as environmental protection and product competition requirements). It also needs to be recognised that the debate is taking place within pre-determined boundaries and in relation to other Commonwealth commitments. A number of existing policy decisions, particularly the Government's commitment to align with United Nations Economic Commission for Europe (UN ECE) vehicle emission standards, may effectively determine the direction and timing of certain decisions in setting the biodiesel standard. There are a number of quality parameters in biodiesel that potentially lead to improved environmental and vehicle performance. This paper presents a discussion of those biodiesel fuel parameters that impact on vehicle emissions and engine operability. The paper also canvasses other issues such as blending biodiesel with petroleum based diesel and warranties.
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Both the Government and the burgeoning biodiesel industry in Australia acknowledge that a quality standard is critical in market development and consumer acceptance. This discussion paper should be used to inform stakeholders about biodiesel and its use as a transport fuel. This discussion paper does not recommend limits for biodiesel parameters nor advocate the use of particular blends of biodiesel. This document seeks comments on key issues and these comments will feed into Government policy making. Stakeholder comment is requested where prompted or on any other aspect of the issues discussed. This paper is open for public and industry written comment until the closing date. After review and assessment of comments a draft standard will be circulated. Environment Australia is obligated to undertake a Regulatory Impact Statement (RIS) as part of this standard setting process. Environment Australia anticipates that a biodiesel standard will be finalised in legislation in the latter half of 2003.
1.2 Structure of Paper The information in this paper is arranged as follows: Chapter 2 provides a background into policy direction and the case for developing national fuel quality standards; Chapter 3 presents information on basic biodiesel chemistry, terminology and feedstocks; Chapter 4 presents some of the impacts of biodiesel use, including emissions; Chapter 5 presents a discussion on biodiesel blends with reference to overseas experience and practice; Chapter 6 discusses the individual quality parameters of biodiesel, impacts on vehicle emissions and engine operability, international trends and test methods; Chapter 7 presents information on impacts of using different types of alcohol in the production of biodiesel; Chapter 8 presents information on the impacts of blending biodiesel with petroleum based diesel; Chapter 9 presents information on the impacts of biodiesel use on diesel engine oil; and Chapter 10 presents information on biodiesel use in relation to vehicle warranties and labelling.
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Referencing Due to the technical nature of the discussion paper and repetitive referencing, the Vancouver system has been used. In the text a superscript number is allocated to each source when it is referred to for the first time. This number becomes the unique identifier of that source; if the source is referred to again, the identifying number is repeated.
1.3 Call for public submissions In order to ensure that the most appropriate fuel quality standards are adopted in Australia, comment on the discussion paper is sought from all interested stakeholders and members of the public. While comments are welcomed on any matter discussed in this paper, attention should also be directed to the specific questions raised throughout the text (in italics). Unless marked as ‘Confidential’, all submissions will be treated as public documents, posted on the Environment Australia (EA) website and provided to the Fuel Standards Consultative Committee (FSCC). Written comments are requested by Friday 23 May 2003 and should be sent to: Mr Daniel Sheedy Clean Fuels and Vehicles Section Environment Australia GPO Box 787 CANBERRA ACT 2601 Or submitted electronically to: [email protected]
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2 BACKGROUND Biodiesel is used as a direct replacement or blend stock component for petroleum based diesel fuel. Petroleum based diesel is also termed conventional diesel, mineral diesel, fossil diesel and petrodiesel. For the purposes of consistency it will be termed ‘diesel’ in this discussion paper. Issues relating to the impacts of diesel use and setting standards for diesel are relevant background information on the development of a biodiesel standard. There are a number of significant pressures to mandate the fuel characteristics of biodiesel under the Fuel Quality Standards Act 2000. The principal reason for ensuring consistency in biodiesel fuel quality is an environmental one – the need to provide fuels that facilitate the adoption of emerging vehicle engine and emission control technologies, a key strategy in managing air pollution and greenhouse gas emissions. This is supported by the need to better manage those fuel parameters that do not impact directly on vehicle technology, but nevertheless contribute to ambient levels of pollutants identified as posing health or environmental problems. Therefore there is a need to ensure that the emission performance of diesel vehicles is not compromised by the quality of the fuel. The development of standards will ensure quality of biodiesel in the market place, certainty for the biodiesel industry and consumer confidence in the product. According to a CSIRO report biodiesel in Australia will be a niche fuel, albeit a very useful one, because there is not sufficient area to grow the plants needed to convert all of Australia’s diesel fuel usage (currently in excess of 13 billion litres annually) to biodiesel.1
2.1 Environmental impacts of transport Transport activities have been identified as the most significant contributor to urban ambient air pollution in Australia, with road vehicles the dominant source of pollutants.2 Motor vehicle emissions are key sources of carbon monoxide, hydrocarbons and oxides of nitrogen. Hydrocarbons and oxides of nitrogen are the precursor pollutants which can combine to form photochemical smog. Diesel fuelled vehicles are a significant source of oxides of nitrogen. The diesel fleet is the major transport source of particles, contributing up to 80% of vehicle produced particles in major cities.3 The reduction of emissions from road transport is a key element of air quality management strategies established by Commonwealth, State and Territory governments to meet the National Environment Protection Measure (NEPM) ambient air quality standards agreed by the National Environment Protection Council (NEPC) in 1998 (see Section 4.1). Motor vehicles emissions are also a significant source of air toxics (Air toxics are pollutants that occur in relatively small volumes, compared with ambient pollutants, but are considered hazardous to health or the environment). Motor vehicle emissions are estimated to make the following contribution to ambient levels of air toxics: benzene 80%; toluene 57%; 1,3 butadiene 76%; formaldehyde 64%; polyaromatic hydrocarbons 42%; xylene 57% (Source: Victorian EPA, December 1999, Air
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Emissions Inventory – Port Phillip Region). There is growing international recognition of the potential health risks associated with exposure to air toxics and of the need for action to minimise the risks. Following the preparatory work completed under the Commonwealth's Living Cities - Air Toxics Program, NEPC decided in June 2001 to commence development of a National Environment Protection Measure for Ambient Air Toxics (AAT NEPM). This NEPM will address, by setting ambient air standards and establishing associated monitoring protocols, the following air toxics: benzene, formaldehyde, polycyclic aromatic hydrocarbons (PAHs), toluene and xylenes (Note: not all of these air toxics are relevant for biodiesel - see Section 4.2 for further information). A second group of air toxics was also identified for which a process for gathering additional monitoring data (to enable their future consideration) is to be examined in conjunction with the development of the NEPM. The AAT NEPM is scheduled for completion in 2003. The Prime Minister announced the establishment of the Australian Greenhouse Office in his statement Safeguarding the Future: Australia’s Response to Climate Change in late 1997. The statement outlined actions designed to reduce air pollution and greenhouse gases, and improve the health of Australian cities. The Commonwealth Government has recently indicated that Australia will continue to develop and invest in programs to meet the greenhouse gas emissions target it agreed at Kyoto in 1997 - 108 percent of the 1990 levels on average over 2008-12. Australia's total net greenhouse gas emissions currently are projected to be 581 Mt CO2-e per year on average over 2008-12, or around 111% of the 1990 Kyoto baseline of 525 Mt CO2-e. Without measures, emissions would have reached 122%; existing measures are projected to reduce emissions growth by 11%, or almost 60 Mt CO2-e per annum. National Greenhouse Gas Inventory data indicate that from 1990 to 2000 national transport emissions grew by 24.2% - one of the fastest growing sectors. In 2000 the transport sector was responsible for 14.2% of Australia's net greenhouse gas emissions. Road transport accounted for 90.2% of total transport greenhouse gas emissions in 2000, or approximately 12.9% of total national emissions. Emissions from passenger vehicles predominate, but light commercial vehicles are a fast growing area (Section 4.1 discusses the impacts of biodiesel use in regard to greenhouse gases.) The outlook for the transport sector continues to be of serious concern. Without reduction measures, emissions from the transport sector are predicted to increase by 54% above 1990 levels by the year 2010. The reduction of emissions from this sector is therefore a key focus of the Government.
2.2 Measures for a Better Environment A number of initiatives with respect to the improved management of transport emissions were announced by the Commonwealth Government in May 1999 as part of A New Tax System for Australia. These initiatives, known collectively as the Measures for a Better Environment, included timetables for Australian harmonisation with international vehicle emission standards (for both petrol and diesel engines) and the reduction of sulfur levels in diesel fuel, as well as foreshadowing the need for changes to petrol specifications.
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The Measures for a Better Environment initiatives also include renewable energy generation, alternative fuel programs and a major Greenhouse Gas Abatement Program.
2.3 Fuel Quality Standards (FQS) Act The National Fuel Quality Standards Act 2000 provides the legislative framework for setting national fuel quality standards. It is the first step in providing a nationally consistent approach to improving the quality of fuel in Australia. The main object of the Act is to regulate the quality of fuel supplied in Australia in order to: reduce the level of pollutants and emissions arising from the use of fuel that
may cause environmental and health problems; facilitate the adoption of better engine technology and emission control
technology; and allow the more effective operation of engines.
The first set of standards for petrol and automotive diesel came into effect on 1 January 2002. The current suite of standards for petrol and diesel are at Appendix A. Standards are also currently under development for Liquefied Petroleum Gas (LPG).
2.4 Transport policy The Commonwealth Government has an ongoing program of introducing new vehicle emission standards to ensure that the air quality benefits of evolving emission control are realised in Australia. New vehicle emission standards are established as Australian Design Rules (ADRs) under the Motor Vehicles Standards Act 1989. In the past, these standards (at least for light vehicles) have been largely based on US vehicle emission standards. The 1997 Australian Academy of Technological Sciences and Engineering (AATSE) report "Urban Air Pollution in Australia" found that new vehicle emission standards were “the long term foundation for maintaining and improving air quality”2. The Report recommended that Australia should, “without delay, move to adopt the current United Nations Economic Commission for Europe (UN ECE) vehicle emission regulations for spark ignition (petrol) and diesel engines, as the basis for certifying all new vehicles sold in Australia”. The Prime Minister, in his 1997 statement Safeguarding the Future - Australia’s Response to Climate Change, identified harmonisation with international vehicle emission standards as a goal of the Commonwealth Government. A target date of 2006 was identified. The statement also specified that the fuel efficiency of vehicles would be improved. In response to the Prime Minister's statement, the Government established new vehicle emission standards for petrol and diesel vehicles in December 1999, to help achieve reductions in emissions of significant pollutants. It is important that the
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expected emissions reductions from the new standards for diesel vehicles are not compromised by their operation on biodiesel. The emissions standards for light duty diesel vehicles (<3.5 tonnes GVM) and heavy duty diesel vehicles (>3.5 tonnes GVM) will be progressively tightened to achieve greater harmonisation. The table below sets out the standards for diesel vehicles which have already been legislated, and the ‘Euro’ equivalents. In the case of heavy duty vehicles, the US standards are permitted as an alternative to the Euro standards. Table 2.1 – ADR standards for light duty and heavy duty diesel vehicles Light duty vehicles
ADR Year Euro standard 79/00 2002/03 Euro 2 79/01 2006/07 Euro 4 Heavy duty vehicles 80/00 2002/03 Euro 3 (US 2000 alternative) 80/01 2006/07 Euro 4 (US 2004 alternative) Note: 2002/03 means ADR applies to new models 1 Jan 02 and to all models 1 Jan 03.
2.5 Key dates Key dates have been identified for the introduction of fuel standards over the period 2000-2010. These dates are strongly influenced by the Government’s timetable for the introduction of new vehicle emission standards, first specified in Measures for a Better Environment, and now gazetted under the Motor Vehicle Standards Act 1989. ADRs 79/00, 79/01, 80/00 and 80/01 apply Euro vehicle emission standards to diesel vehicles sold in Australia. It is important to ensure the national availability of fuel of the appropriate quality to support the new diesel vehicle technologies required to meet these standards. Key dates are as follows: - harmonisation with Euro 2/3 diesel fuel specifications by 1 January 2002; and - harmonisation with Euro 4 diesel fuel specifications by 1 January 2006. In the case of diesel, the proposed dates for new fuel standards were established in Measures for a Better Environment through its determination of specific dates for mandatory changes to sulfur content. Changes to other key diesel parameters should logically be coupled with these required sulfur content changes. A review is currently underway under the auspices of the national Motor Vehicle Environment Committee to consider appropriate vehicle and fuel standards for the post 2007 period.
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2.6 Harmonisation with the European Union fuel standards Recent changes to European union (EU) fuel specifications have been driven by vehicle emission requirements and by engine emission control technologies, with new emission control standards coupled with mandated fuel quality and compositional requirements for petrol and diesel fuel. It is recognised, however, that recent changes to the EU fuel specifications have also been designed to address a number of other issues, some of which are specific to EU member countries. While the standards include technology-enabling fuel specifications they are also designed to contribute directly to the management of air pollutants identified as posing significant health or environmental problems within the European Union. While there are similarities between Europe and Australia in terms of public exposure to air pollutants of concern, there are also some significant differences in type and severity of problems. The most recent Australian State of the Environment (SoE) Report found that while Australian urban ambient air quality was good in world terms, there are still more challenges. The quality of urban air has generally improved or remained constant for most years, but emission of pollutants in cities, mainly from vehicles, remains a concern.4
2.7 General principles and policy requirements As noted above, the principal driver under the Fuel Quality Standards Act 2000 for changes to fuel quality specifications is an environmental one – that is, the need to provide fuels which facilitate the adoption of emerging vehicle engine and emission control technologies. The decision to harmonise Australian vehicle emission standards with UN ECE emission standards (as best representing international standards – see below), effectively gives rise to a starting premise that Australian fuel specifications should be harmonised with the matching fuel specifications. (Note: the UN ECE does not set fuel standards. However the UN ECE vehicle emission Regulations and the European Community (EC) vehicle emissions Directives are technically equivalent. Thus the EC fuel standards Directives, which are designed to support the EC vehicle emissions Directives, are also the appropriate standards to ensure compliance with the UN ECE Regulations). ‘International’ standards The regulations developed by the UN ECE meet the definition of an ‘international’ standard in the vehicle standards field (as opposed to national standards such as the US). The UN ECE vehicle emission standards were therefore selected for adoption in Australia to give effect to the goal of ‘harmonisation with international vehicle emission standards’. The Japanese Government has also made a commitment to harmonisation with UN ECE vehicle standards. Most other Asian countries, and indeed the majority of countries in the world, are moving to adopt UN ECE regulations on emission standards (or the equivalent EC Directives). The terms ‘Euro2’, ‘Euro 3’ and ‘Euro 4’ are common terminology used to describe the progressively more stringent versions of the UN ECE standards.5
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A key issue is Government policy with respect to harmonisation, trade facilitation and efficiency. The adoption of UN ECE vehicle emission standards (which gives rise to the premise that Australian fuel specifications should be harmonised with European fuel specifications) is consistent with the Principles and Guidelines for National Standard Setting and Regulatory Action by Ministerial Councils and Standard Setting Bodies laid down by the Council of Australian Governments (COAG). The COAG principles state that:
Wherever possible, regulatory measures or standards should be compatible with relevant international or internationally accepted standards or practices in order to minimize the impediments to trade. Compatibility in this context does not necessarily imply uniformity, however.6
The fuel quality standards development process, and the development of the preferred Commonwealth position, has therefore been based on the following general guiding principles, and specific Government policy decisions.
2.7.1 Guiding Principles The starting premise for the development of biodiesel fuel quality standards - harmonisation with European fuel specifications - is subject to a number of qualifications. The first of these are the environmental and industry policy decisions previously announced by the Government. These establish a number of criteria, and pre-determine a number of issues, in relation to the development of national fuel quality standards. These are then further qualified by the need to take into account a number of more general, but equally important Commonwealth Government principles, such as those addressing legislative / regulatory approaches and competition policy. The guiding principles for the development of national biodiesel standards are:
1. Fuel standards are intended to manage those fuel qualities/parameters that are known to have the potential to impact adversely on the environment.
2. Fuel standards should be compatible with relevant international or internationally accepted standards in order not to impede competition and trade.
3. Fuel standards are intended to be mandated and implemented on a national basis. In particular, fuel standards that are technology enabling must apply nationally. Local environmental circumstances may, however, dictate variation within the national standard to achieve environmental outcomes.7 • Consideration will be given to State by State establishment of fuel
standards that address airshed specific environmental conditions, however, in such cases a national standard may be determined as a default.
4. Fuel standards will apply to, and be enforced equally in respect of, imports as well as domestically produced fuels.7 • Fuel standards must not impede competition, either between Australian
refiners, or with imported refined product.
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5. Fuel standards that directly address environmental or health issues will be determined on the basis of Australian-specific requirements. In such instances, harmonisation with European specifications may be neither necessary nor desirable.
6. The timetable for the introduction of new fuel standards will be based on Australian requirements. Harmonisation, in terms of timing, will not be based on European or any other regional timetable, except where there is a previous policy decision to this effect or the standard is technology enabling and the need for such harmonisation is clearly demonstrated.
7. Consideration will be given to setting standards that provide, as far as possible, flexibility in terms of compliance, providing • flexibility provisions must not impede competition or trade; and • flexibility provisions must not add significantly to legislative/regulatory
complexity or implementation/enforcement costs to Government.
2.8 International biodiesel standards The European Committee for Standardisation (CEN) is responsible for standardisation on a European level. CEN is currently finalising a biodiesel fuel quality standard for Fatty Acid Methyl Ester (FAME) for use as fuel for diesel engines. The standard is currently in draft form and titled prEN 14214 – Automotive fuels – Fatty acid methyl esters (FAME) for diesel engines – Requirements and test methods. If the draft becomes a European standard, CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. CEN members are the national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. If accepted the standard will specify the requirements and test methods for marketed and delivered biodiesel to be used as either automotive fuel for diesel engines (100% - sole diesel engine fuel – B100) or as an extender for automotive fuel for diesel engines in accordance with the requirements of EN 590 (the CEN diesel standard). At 100% concentration it is applicable to fuel for use in diesel engine vehicles designed or subsequently adapted to run on 100% FAME. An amendment to EN 590 was issued to allow a 5% incorporation of biodiesel into diesel fuel. There are currently several national biodiesel standards in European countries such as Germany, Austria and France. Of these, the German DIN 51606 standard is one of the best developed and most stringent. In the US a standard for biodiesel (American Society for Testing and Materials -ASTM D 6751 – Standard Specification for Biodiesel Fuel (B100) Blend Stock for Distillate Fuels) was finalised in May 2002. The standard does not include the same number of parameters as prEN 14214 but the parameters that coincide have similar limits. The specification covers low sulfur biodiesel (B100) for use as a blend component with diesel fuel oils defined by ASTM D 975 Grades 1-D, 2-D, and low sulfur 1-D and 2-D.
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The ASTM D 6751 standard includes information on biodiesel blends and states that a considerable amount of experience exists in the US with 20% blend of biodiesel, primarily produced from soybean oil. In the US 99% of biodiesel is used in blends of 20% or less (approximately 24% as B5/B2, 75% as B20 and 1% as B100). Although B100 can be used, it is recommended that blends of over 20% should be evaluated on a case by case basis until further experience is available. The standard also advises that the Fuel Injection Equipment (FIE) manufacturers should always be consulted regarding the application limits of their products. A summary of international trends in biodiesel use is at Appendix B.
2.9 The case for a national biodiesel standard in Australia A national biodiesel standard would specify parameters to ensure consistency in biodiesel quality, thus ensuring the availability of fuel that:
• reduces the level of pollutants and emissions arising from the use of fuel that may cause environmental and health problems;
• facilitates the adoption of better vehicle and emission control technologies; • allows more effective operation of engines; and • consistently meets consumer expectations.
The Fuel Quality Standards Act 2000 provides a legislative framework for setting national fuel standards for Australia. The Fuel Quality Standards Regulations 20018 provide coverage under legislation for the development of a standard for biodiesel, among other fuels. Comment: What is your view on the need to develop a mandated national fuel quality standard for biodiesel? The decision to harmonise Australian vehicle emission standards with UN ECE emission standards effectively gives rise to a starting premise that an Australian biodiesel fuel specification should be harmonised with European fuel specifications. However, US biodiesel specifications also appear applicable to the Australian context - particularly with regard to emissions standards for heavy duty diesel vehicles. As the European and US biodiesel standards are quite similar this potentially does not cause any major issues.
Comment: What is your view on harmonisation of any Australian biodiesel standard with European and/or US biodiesel specifications?
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3 BIODIESEL
3.1 Basic chemistry and terminology The Fuel Standards Regulations 2001 under the Fuel Quality Standards Act 2000 define biodiesel as “a diesel fuel obtained by esterification of oil derived from plants or animals.”8 Esterification is the conversion of a compound into an ester. An ester is a compound formed by the reaction between an acid and an alcohol with the elimination of a molecule of water. Biodiesel is a generic name for mono-alkyl esters of long chain fatty acids derived from renewable lipid sources (i.e. vegetable oils, animal fats or used cooking oils and fats). Mono-alkyl esters of long chain fatty acids are produced from the esterification of triglycerides (three fatty esters connected to a glycerine ‘backbone’) with an alcohol (typically methanol or ethanol) in the presence of a catalyst.9 Production of mono-alkyl esters of long chain fatty acids requires the following:
- A feedstock source of triglycerides. Vegetable oils (eg soyabean oil, rapeseed/canola oil, palm oil), animal fats (eg beef tallow), and waste cooking oils (eg reused frying oil) can all be used as feedstocks in biodiesel production.
- An alcohol. The most common alcohol used in biodiesel production is methanol, but other alcohols, typically ethanol, can be used.
- A catalyst. Most biodiesel reactions are alkali catalysed, with the most common alkali source as potassium hydroxide. Sodium hydroxide can also be used as a catalyst.
The major products of the esterification reaction are:
- mono-alkyl esters of long chain fatty acids (the biodiesel); and - glycerol
Biodiesel is produced by a reaction of a vegetable oil or an animal fat with an alcohol, such as ethanol or methanol, in the presence of a catalyst to yield mono-alkyl esters, and glycerine, which is removed. The alcohol is charged in excess to assist in quick conversion and recovered for reuse. The catalyst is usually sodium or potassium hydroxide which has already been mixed with the alcohol.10 The finished biodiesel derives some 10% of its mass from the reacted alcohol. The alcohol used in this reaction may or may not come from renewable resources.11 If methanol is used the result is methyl esters and if ethanol is used the result is ethyl esters. The draft CEN biodiesel standard, prEN 14214, defines biodiesel as Fatty Acid Methyl Ester (FAME), therefore restricting biodiesel to be produced with methanol. The US ASTM D 6751 standard does not specify the type of alcohol to be used in the production of biodiesel.
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Depending on the feedstocks and processes employed, by-products may include glycerine, fatty acids, fertiliser and oil seed meal (for grain feed stocks). Waste water also results from biodiesel production. This may or may not be treated on site. Biodiesel may have other terminology depending on the feedstocks used to produce it, for example Fatty Acid Methyl Ester (FAME), Plant Methyl Ester (PME), Rapeseed Methyl Ester (RSME or RME), Vegetable Oil Methyl Ester (VOME) or Soybean Oil Methyl Ester (SOME). Further detailed information on the chemistry of biodiesel and biodiesel production is at Appendix C. ASTM D 6751–02 standard defines biodiesel as “a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100.”11 B100 is neat biodiesel. Biodiesel blended with diesel fuel is referred to as a biodiesel blend ; for example, B5 - a 5% biodiesel and 95% diesel blend.
3.2 Feedstocks Current potential feedstocks for biodiesel include vegetable oils, animal fats, and waste cooking oils and fats. The fuel properties of biodiesel will greatly depend on the fatty acid chains of the feedstock used for esterification. For example, biodiesel produced from tallow, a highly saturated fat, will tend to have a higher freezing point that can inhibit cold flow properties. However an advantage of using tallow is that the biodiesel will have a higher cetane number, a desirable property in diesel fuel. Biodiesel feedstocks and/or production technology can be influenced through the quality standard, for example by specifying, as does pr EN 14214, that methanol must be used as the alcohol. Further information on the effects of different feedstocks on biodiesel fuel parameters is available at Appendix D. Comment: Do you consider that an Australian standard for biodiesel should prescribe feedstocks or production technologies, or should the standard only address characteristics and composition of biodiesel?
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4 IMPACTS OF BIODIESEL USE Impacts of biodiesel use as a transport fuel include improvement in some vehicle emissions and improvement in some aspects of engine operability where the biodiesel used is of suitable quality.
4.1 Emissions There are a number of biodiesel emissions studies. Analysis, and therefore conclusions, in these studies vary in relation to type of biodiesel used (i.e. feedstocks, process technology, etc), blends of biodiesel used, types of engine used, fuel injection methodology, engine load, sampling methodology, experimental designs and test methods used. As a result, there is a large variation in reported emissions for biodiesel use. This is shown in results of the Comparison of Transport Fuels report for greenhouse gas emissions (GHG), particulate matter (PM), nitrogen oxides (NOx) and hydrocarbon (HC) emissions from biodiesel use where variability in the results is very evident.1 The study incorporates a desk top study and literature review of existing Australian and overseas data concerning the emissions characteristics of alternative and conventional fuels that are or may be suitable for use in road vehicles weighing 4.5 tonnes gross vehicle mass (GVM) or more. The study found that compared to low sulfur diesel (LSD - < 500ppm), on a full fuel cycle basis, 100% biodiesel generally resulted in slightly lower emissions of particulate matter, higher emissions of NOx, significantly lower greenhouse gas emissions and air toxics emissions ranging from ‘much the same’ to ‘significantly lower’ depending on the feedstock used. However, the results of this study need to be treated with caution as in some cases the data was very limited, and in most cases the data was derived from testing vehicles not indicative of current technology engines. US Environmental Protection Agency (EPA) Tier I and II testing to quantify emission characteristics as required by Section 211(b) of the Clean Air Act Amendments has been carried out on biodiesel.12 ‘US EPA Tier I and II testing’ As part of the Clean Air Act Amendments enacted by the US Congress in 1990, under section 211(b), the US EPA was directed to ensure that any new commercially available motor vehicle fuel or fuel additives would not present an increased health risk to the public. Under this directive, EPA established a fuel and fuel additive registration program including a set of testing protocols, given in CFR Title 40 Part 79. These tests are designed to provide sufficient data for EPA to assess the impact of a given fuel or additive on the potential health risks posed by the motor vehicle exhaust. The test protocol include a detailed characterization of the exhaust emissions of one or more engines while operating with the fuel or additive in question.12 This study used three different test engines, a highway truck, an urban transit bus and a full-size pickup truck. The study found that, when compared to US Grade No.2-D fuel (<500ppm), the use of B20 reduced:
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total hydrocarbons by up to 30%; carbon monoxide up to 20%; total particulate matter up to 15%; and increased NOx by less than 3%.
US research also documents that the ozone forming potential of the hydrocarbon emissions of pure biodiesel (B100) is nearly 50% less than that of petroleum fuel.13 More recently, due to the increasing interest in the use of biodiesel, the US EPA conducted a comprehensive analysis of the emission impacts of biodiesel using publicly available data. This assessment was released in October 2002 as a draft technical report.14 As the majority of available data was collected on heavy-duty highway engines, this data formed the basis of the analysis.14 (Heavy-duty highway vehicles (HDHV) are defined by US Federal vehicle weight definitions as being greater than 8,500 pounds gross vehicle weight rating (GVWR)). The average effects are shown in Figure – 4.1. Figure 4.1 - Average emission impacts of biodiesel for heavy-duty highway engines
(Source - United States Environmental Protection Agency – A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions, Draft Technical Report. EPA420-P-02-001, October 2002).14 In the US one of the most common blends of biodiesel contains 20 volume percent biodiesel with 80 volume percent diesel (B20). Table 4.1 shows the estimated emission impacts for B20 (soybean-based biodiesel) use in the current US heavy duty fleet.
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Table 4.1 - Emission impacts of B20 (soybean-based biodiesel) added to an average base fuel. Percent change in emissions NOx + 2.0 % PM - 10.1 % HC - 21.1 % CO - 11.0 % (Source: United States Environmental Protection Agency – A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions, Draft Technical Report. EPA420-P-02-001, October 2002).14 This report presents a high level of confidence in estimates for the current US diesel fleet. However, the database contained no engines equipped with exhaust gas recirculation (EGR), NOx adsorbers, or PM traps. In addition, approximately 98% of the data was collected on 1997 or earlier model engines. Therefore estimates of biodiesel impacts on emissions may be less accurate for future fleets than they are for the current US diesel fleet. The US EPA investigation also discovered that biodiesel impacts on emissions varied depending on the type of biodiesel (soybean, rapeseed, or animal fats) and on the type of diesel to which the biodiesel was added. With one minor exception, emission impacts of biodiesel did not appear to differ by engine model year. Predictions concerning the impacts of biodiesel use on emissions from light-duty diesel vehicles or diesel-powered non-road equipment were not made. An unambiguous difference in exhaust CO2 emissions between biodiesel and diesel could not be found in the draft report. However, the study notes that CO2 benefits commonly attributed to biodiesel are the result of the renewability of the biodiesel feedstock, not the comparative exhaust CO2 emissions. An investigation into the renewability of biodiesel was beyond the scope of this US EPA report.14 A US study performed jointly by the United States Department of Agriculture (USDA) and the United States Department of Energy (DOE) in 1998 found that biodiesel production and use, in comparison to diesel, produces 78.5% less CO2 emissions, based on the use of B100 - soy methyl ester.15 The CSIRO analysis of transport fuels states that on a life-cycle basis, biodiesel is more climate-friendly than diesel and biodiesel from vegetable crops is much more so than biodiesel from tallow. The carbon emissions from agricultural production and fertilizer production are less than the exbodied emissions from diesel made from fossil fuels.1 In assessing what additional issues should be addressed the US EPA draft report states that in order to more accurately determine the emission impacts of biodiesel, it would be useful to correlate actual fuel property measurements of biodiesel with emissions rather than simply using broad source categorization as undertaken in the technical report.14
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4.2 Toxicity Impact on human health represents a significant criterion as to the suitability of a fuel for commercial applications. Health effects can be measured in terms of toxicity to the human body as well as health impacts due to exhaust emissions. Tests conducted by WIL Research Laboratories investigated toxicity of B20 and B100 on laboratory rats.16 These tests showed that biodiesel is less toxic than diesel fuel. US EPA 2002 draft technical report predicted aggregate toxics to be reduced, but the impacts differ from one toxic compound to another. The conclusions regarding the effects of biodiesel on toxics is preliminary and only potentially indicative of the true effects, due to the limited nature of the data.14 Sharp found that biodiesel use reduces targeted polycyclic aromatic hydrocarbon (PAH) emissions and nitrited PAH (nPAH) compounds when compared to diesel exhaust. PAH and nPAH compounds have been identified as potential cancer causing compounds. Targeted PAH compounds were reduced by 75 to 85 percent, with the exception of benzo(a)anthracene, which was reduced by roughly 50 percent. Target nPAH compounds were also reduced dramatically with biodiesel fuel, with 2-nitrofluorene and 1-nitropyrene reduced by 90 percent, and the rest of the nPAH compounds reduced to only trace levels. All of these reductions are due to the fact the biodiesel fuel contains no aromatic compounds.12 CSIRO report that there appear to be no health risks of air toxic emissions from biodiesel with respect to mortality, toxicity, fertility or tetratology (the branch of embryology and pathology that deals with abnormal development and congenital malformations)17. All air toxic emissions from biodiesel are lower than equivalent diesel emissions except for acrolein. Though highly toxic, the slight increase in acrolein is offset by the decrease in the equally toxic aldehydes.1 These findings contrast the US EPA report that states that the effect of biodiesel on emissions for benzene, 1,3 butadiene and toluene could not be determined quantitatively or qualitatively.14 The report also found a real reduction in acrolein emissions with increasing biodiesel concentration but the effect was simply too small to be captured is a statistically significant way. 14
4.3 Lubricity Lubricity is not identified as a fuel quality parameter in international biodiesel standards. However, available data indicate that any addition of biodiesel to diesel would improve the lubricity of the biodiesel blend. Fuel lubricates some moving parts of diesel pumps and injectors. To avoid excessive wear, the fuel must have some minimum amount of lubricity. Lubricity is the ability to reduce friction between solid surfaces in relative motion.18 In the absence of sufficient lubricity in fuel, vehicles can suffer excessive pump wear and, in some cases, engine failure. In addition, certain modes of deterioration in the injection system could also affect the combustion process and hence emissions.19 The lubricity of diesel fuel is dependent on a wide variety of factors, which include the crude oil source from which the fuel was produced, the refining processes used to produce the fuel, how the fuel has been handled throughout the distribution chain, and
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the inclusion of lubricity enhancing additives whether alone or in a package with other performance enhancing additives. Typically, US Grade No.1-D fuel (commonly referred to as kerosene), which is used in colder climates, has poorer lubricity than US Grade No.2-D fuel. Lubricity enhancing compounds are naturally present in diesel derived from crude oil. The process of hydrotreating to reduce sulfur levels destroys some of these naturally occurring lubricants. Accordingly, to prevent problems arising from the introduction of low sulfur grades of diesel, lubricity additives have been developed to compensate for the deterioration in natural lubricity of low sulfur diesel. It should be noted that these lubricity additives do not stop certain rubber seal failures that can result from lowering the aromatics content of diesel.20 Because of its importance to diesel engine performance and, ultimately, emissions, lubricity is considered to be an important fuel performance property. In light of this, lubricity was included in the recent amendments to the national diesel fuel quality standards.21 The lubricity standard sets a specification of 0.460mm and prescribes test method IP450 in line with the European standards. Diesel fuels with sulfur levels in excess of 500 ppm typically provide sufficient natural lubricity. As Australian fuel quality standards are progressively tightened, and sulfur levels are reduced, the need to use additives to manage diesel lubricity will increase. In cooperation with the US National Biodiesel Board, lubricity tests were completed by Stanadyne Automotive (a US manufacturer of diesel fuel injection equipment). Conventional diesel fuel (US Grade No.2-D) was tested, as well as problem diesel fuels such as US Grade No.1-D, Canadian number-2, military JP-8 fuel, and new ultra low sulphur diesel fuel with less than 15 ppm sulphur. The results indicate that the inclusion of 2% biodiesel into any diesel fuel will be sufficient to address the lubricity concerns that diesel engine companies and diesel fuel injection equipment companies have with these existing diesel fuels. Stanadyne state that inclusion of 2% biodiesel is desirable for two reasons. First, it would eliminate the inherent variability associated with the use of other additives and whether sufficient additive was used to make the fuel fully lubricious. Second, Stanadyne considers biodiesel a fuel or a fuel component--not an additive. It is possible to burn pure biodiesel in conventional diesel engines. Thus, if more biodiesel is added than required to increase lubricity, there will not be the adverse consequences that might be seen if other lubricity additives are dosed at too high a level.22
4.4 Biodegradability Biodegradability refers to the ease with which compounds break down into simple molecules found in the environment, such as carbon dioxide and water. The predominant biodegrading mechanism is microbial activity. Biodegradability is desirable in the event of a spill or leak of fuel to the environment. Conversely, fuel stability is an important characteristic to be considered in regard to the storage, handling and distribution of diesel and biodiesel. This is considered in section 4.8 below.
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Many of the components of diesel biodegrade slowly or are non-biodegradable.23 Diesel consists of a complex array of hydrocarbons including alkanes, branched alkanes, cycloalkanes, and aromatic compounds. Many species of microorganisms can degrade simple alkane components, other classes of diesel hydrocarbons, such as, branched and aromatic hydrocarbons are less susceptible to microbial degradation.23 Microbial degradation predominantly begins where oxygen is attached to the substrate.23,24 Diesel consists of very few components with oxygen attached and therefore is not considered to be biologically active.24 Biodiesel consists of even hydrocarbon chains in ester form with two oxygen atoms attached making them very biologically active. 24 In the process of degradation, fatty acids are oxidised and degraded to acetic acid and a fatty acid with two fewer carbons.24 Biodiesel fuels of rape ethyl ester, rape methyl ester, soyate ethyl ester and soyate methyl ester are readily ‘biodegradable’ in aquatic environments according to the US EPA standard and have a relatively high biodegradation rate in the aquatic environment.24 Zhang24 showed the maximum biodegradability of rape methyl ester, rape ethyl ester, soyate methyl ester and soyate ethyl ester was 88.49% in 28 days. The maximum biodegradability of diesel fuel after 28 days was shown to be approximately 26.24%.24 Tyson25 states similar results in that biodiesel degrades approximately four times faster than diesel and reports that, within 28 days, pure biodiesel (B100) degrades 85 to 88% in water. Blending biodiesel with diesel accelerates its biodegradability and it has been reported that blends of 20% biodiesel with 80% diesel fuel degrade twice as fast as neat diesel.25 Furthermore, experiments with blends of biodiesel and diesel at concentrations ranging from 20% to 80%, showed that biodiesel can promote and speed up the biodegradation of diesel as the more biodiesel present in a biodiesel/diesel mixture the faster the degradation rate.24 Biodegradation under aerobic conditions involves microorganism metabolisation of a substance into two final products, CO2 and water. Therefore, CO2 is presumed to be the prevalent indicator of organic substance breakdown. This assumes that the substrate is the only carbon source. Therefore, the amount of CO2 evolved will be proportional to the carbons consumed by the microorganisms from the test substrate.26 Stolz23 showed that soy derived biodiesel can be biodegraded by bacteria under aerobic and anaerobic conditions in freshwater and soil environments (bacterial concentrations at the beginning of these experiments were 105 cells/ml, for both aerobic and anaerobic conditions). These findings are significant as diesel is involved in approximately 21% of all petroleum oil spill incidents.23 Diesel is degradable under aerobic conditions, although at rates approximately four times less than biodiesel, however, diesel resists biodegradation under anaerobic conditions23. Therefore, the environmental impact of a biodiesel and/or biodiesel blend spill, as a result of transportation, use and storage, should be far less than diesel.
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4.5 Niche markets based on the biodegradability of biodiesel Experience in other countries where biodiesel has reached market production indicates that biodiesel sales are concentrated in niche markets where environmental benefits or competitive advantage are the basis for purchasing decisions. The biodegradability of biodiesel has opened up a niche market in the marine sector. As biodiesel biodegrades faster than diesel in aquatic environments and is less toxic than diesel there is a significant potential environmental benefit from using biodiesel in both fresh and salt water environments.
4.6 Energy Balance The energy balance for renewable fuels is defined as the amount of energy required to produce the fuel compared to the amount of energy released by the fuel when it is burned. One of the potential disadvantages of some renewable fuels is their low energy balance. If the energy balance is low, then it could possibly take more energy to produce the fuel than would be released when it is burned, resulting in merely a transfer of energy from one form to another without increasing the overall energy available to society. A joint independent study of the US Departments of Agriculture and Energy found that biodiesel has a positive energy balance.15 A conservative approach was used, beginning with bare ground and ending with finished biodiesel produced from soybeans. The results from this study indicated that for every one unit of energy needed to produce biodiesel from soybeans, 3.24 units of energy are gained (compared to 0.83 for diesel).
4.7 Fuel economy On a volumetric basis biodiesel contains roughly 10% less energy than diesel and therefore there is a loss in fuel economy. Fuel economy, power, and torque are proportional to the heating value of biodiesel or the biodiesel blend. For example B20 tends to reduce power, torque and fuel economy by slightly less than 2%.25 A more recent US EPA study also predicted that biodiesel will reduce fuel economy by 1-2 percent for a 20 percent volume biodiesel blend.14
4.8 Storage, Handling and Distribution Biodiesel is no more dangerous in handling and storage than diesel. No special safety containers are required for biodiesel. Biodiesel has a flash point higher than diesel. Many diesel fuel suppliers recommend storing diesel for no more than three to six months unless using a stabilising additive. The current industry recommendation is that biodiesel or biodiesel blends also be used within six months.27 A longer shelf life is possible and storage enhancing additives can provide additional benefits. In the US storage life has not been a major issue in the field, however the industry has a large program underway to develop quicker and more reliable bench tests for measuring the long-term stability of biodiesel and the impact of storage enhancing additives.28
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Acid numbers in biodiesel and biodiesel blends will become elevated if the fuel ages, or if it was not properly manufactured. Raised acid numbers have been associated with fuel system deposits and reduce the life of fuel pumps and filters.25 Residual methanol (from production) in the fuel will reduce the flash point of the fuel and can also affect fuel pumps, seals, elastomers.25 Biodiesel does gel faster in cold conditions than most diesel, however, below a 20% blend the cold flow properties of the blend are very similar to those of the diesel base, and blends below 5% are indistinguishable.28 Pure biodiesel and biodiesel blends should be stored at temperatures higher than the pour point of the fuel.25 Biodiesel blends will not separate in the presence of water however it is recommended that good ‘housekeeping’ be maintained. This is in respect to tank and fuel maintenance, to ensure water in storage systems is monitored and minimised. Biodiesel is slightly heavier than diesel fuel (specific gravity of 0.88 compared to diesel at 0.85) therefore splash blending biodiesel on top of diesel fuel is the common mixing procedure. This ensures the fuels are mixed properly.25 Additives Additives are being investigated to control operability properties of biodiesel, such as cold flow and NOx emissions, as well as storage properties.
Comment: Do you wish to comment on any aspects of the impacts of biodiesel use raised in this chapter?
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5 – BIODIESEL BLENDS
5.1 The European Union experience In 1997 the European Union gave a mandate to CEN to develop standards and test methods for biodiesel as a sole diesel engine fuel (100%) and biodiesel as extender to diesel engine fuel according to the CEN diesel standard EN590. During this process it was decided to elaborate only one standard being valid for both, biodiesel as sole fuel and as a blending component to EN590 diesel fuel.29 A summary of international trends in biodiesel use is at Appendix B. This summary includes details of the types of biodiesel blends used. A brief list of some examples of blends are given below. Germany - B100 Austria - B100 or as a voluntary blend of up to B3 France - B5 predominant with some B30 in captive fleets Italy - B5
5.2 The United States experience A significant amount of discussion within the industry has occurred regarding the concentration of biodiesel used in blends with diesel and the resulting impact on the specification. Biodiesel is completely miscible with both US Grade No.1-D and 2-D fuel. It can be used as a 100% replacement for diesel, or as a blending stock. At 2002 world market prices for crude petroleum oil and animal fats and vegetable oils, the cost of biodiesel is more than diesel. Therefore, applications for biodiesel are primarily those where it can provide value added benefits (emissions, biodegradability, lubricity, etc.) or those where it represents a cost competitive option to meet legislative initiatives (alternative fuels, greenhouse gas reduction, economic development, etc.) for which diesel is not an option. Most of the experience with biodiesel in the US has been with 20% blends of biodiesel with 80% diesel. The market share is approximately 75% B20, 24% B5/B2 and 1% B100). This appears to be a compromise between emissions reduction and cost, and also minimises cold weather impacts. There are additional markets, however, which are using 100% biodiesel such as in marine applications where the biodegradability of pure biodiesel is important. It is also anticipated that in the US biodiesel, when used as a blend with diesel, will most likely be produced by someone other than the seller of the finished blend. This also creates a need for a standard for pure biodiesel before blending. The standard adopted by ASTM, therefore, is for the pure (or 100%) biodiesel. The rationale is that if biodiesel conforms to the pure standard then it can be blended with diesel in any proportion.
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Since most experience in the US has been with a 20% blend of biodiesel with 80% diesel, engine manufacturers have requested a caveat be added to the specification that blends over 20% be evaluated on a case by case basis by the engine manufacturer until more data become available.
5.3 The Australian situation In Australia, the allowable amount of biodiesel blended into diesel needs to be addressed. There are both technical and excise issues associated with the blending of biodiesel. Environment Australia understands that some potential biodiesel producers will not go into production until the present excise arrangements are changed. At present neat biodiesel, B100, is exempt from excise. However when blended, the blend component of biodiesel attracts the same rate of excise as the diesel fuel. In Europe it appears there is no intention of a setting a quality standard for biodiesel blends as this is not seen to be practical.30 Environment Australia is equally of this view. In Europe an option to prevent the blending of low quality biodiesel is to establish dedicated blending facilities. This would allow samples to be taken for quality control. 30 This is a comprehensive and highly regulated approach which may not be practical for the Australian biodiesel industry at this stage. A less rigorous option to ensure a quality blend is to ensure both blend stocks meet relevant quality standards but not control the blending activities or the percentage blended. This broadly follows the rationale of the US. It would seem logical to look to Europe and the US for guidance on this issue, as a large proportion of Australia’s diesel vehicles are imported from these countries and there is far greater experience with the use of biodiesel blends. Comment: What are your views on biodiesel blends? Sections 6, 8, 9 and 10 should be referred to when commenting on this section.
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6 BIODIESEL PARAMETERS This section of the discussion paper outlines parameters for biodiesel that can potentially be specified in a biodiesel quality standard. A brief description of the parameter, its impact on vehicle emissions and engine operability, international trends in standards for the parameter and test methods for the parameter are presented. Several countries have already introduced biodiesel standards. Table 6.1 shows a selected comparison of international standards for biodiesel. This table has been compiled with the significant assistance of Steve Howell (MARC-IV) and Werner Körbitz (Austrian Biofuels Institute). Limits and test methods for prEN 14214 FAME standard are preliminary as the standard is currently being finalised. Many of the test methods included in prEN14214 were the subject of inter-laboratory testing to determine the applicability of the method and its precision in relation to different sources of fatty acid methyl esters. The FAME samples tested were produced from rapeseed and sunflower oils. The detailed requirements for Biodiesel (B100) in the US ASTM D 6751-02 includes a caveat that, to meet special operating conditions, modifications of individual limiting requirements may be agreed upon between purchaser, seller, and manufacturer. The test methods indicated in the standard are the approved referee methods. Other acceptable methods are also listed in the standard.11
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Table 6.1: Comparison of international biodiesel standards
Austria Germany Italy France Sweden Czechia EU USA
Standard/ Specification Units ÖNORM
C1191 DIN
51606 UNI
10635 Journal Officiel
SS 155436
CSN 656507
prEN 14214(10)
ASTM D6751-02
Application FAME FAME VOME VOME (4) VOME RME FAMEDate 1-Jul-97 Sep-97 21-Apr-97 14-Sep-97 27-Nov-96 Sep. 1998 2002 2002
Density 15°C kg/m³ 850 - 890 875 – 900 860 - 900 870 - 900 870 - 900 870 - 900 860 - 900 − 20°C mm²/s − − − − − − − − Kinematic
Viscosity 40°C mm²/s 3.5 - 5.0 3.5 - 5.0 3.5 - 5.0 3.5 - 5.0 3.5 - 5.0 3.5 - 5.0 3.5 - 5.0 1.9 - 6.0 (12) I.B.P − − − − − °C − − ≥ 3005% − − °C − − − − − ≥ 300Distillation
95% − − ≤ °C − − ≤ 360 ≤ 360 ≤ 360 360 (13)
Flashpoint ≥ °C ≥ 100 ≥ 110 ≥ 100 ≥ 100 ≥ 100 ≥ 110 ≥ 120 130
CFPP ≤ ≤ − − ≤ − summer °C ≤ 0 0 0 - 5 ≤ 5 / ≤ 0 (11)
Intersec °C − ≤ -10 − − ≤ − -5 ≤ -5 / ≤ -10 − winter °C ≤ -15 − − ≤ -20 ≤ -15 ≤ -15 ≤ -15 / ≤ -20 −
Summer − ≤ ≤ − °C − − − ≤ -10 - 8 0Pourpoint Winter − − °C − − − − − ≤ - 20
Cloud Point °C − − − − − − − (14) Total Sulphur % mass ≤ 0.02 − ≤ 0.01 ≤ 0.01 ≤ 0.001 ≤ 0.02 ≤ 0.001 ≤ 0.05 (15)
CCR 100% % mass − − − ≤ 0.05 ≤ 0.05 − ≤ 0.05 ≤ 0.05
10% % mass − − ≤ 0.5 (3) − − − ≤ 0.3 (5) ≤ 0.30
Sulfated Ash % mass ≤ 0.02 − − − − ≤ 0.03 ≤ 0.02 ≤ 0.02
Ash (Oxid ash) % mass − − ≤ 0.01 − − − ≤ 0.01 ≤ 0.02Water content mg/kg − ≤ 300 − ≤ 700 ≤ 200 ≤ 300 ≤ 500 ≤ 500
Total contamination mg/kg − ≤ 20 − − ≤ ≤ − ≤ 20 24 24
Water and Sediment
% vol (1) − − − (7) − − ≤ 0.05
25
Austria Germany Italy France Sweden Czechia EU USA
Standard/ Specification ÖNORM
C1191 DIN
51606 UNI
10635 Journal Officiel
SS 155436
CSN 656507
prEN 14214prEN 14213
ASTM D6751-02
Corrosion (Cu) 3h at 50°C − 1 − − − 1 Class 1 ≤ No. 3
Cetane No. − ≥ 49 − ≥ ≥ ≥ ≥ 49 ≥ 49 ≥ 48 48 51 47
Acid No. mg KOH/g ≤ 0.80 ≤ ≤ ≤ 0.50 ≤ 0.5 ≤ 0.5 ≤ 0.6 ≤ 0.5 0.5 0.8 Oxidation Stability 110°C − hours − Is to
specify − − (8) − ≥ 6
Methanol content % mass ≤ 0.20 − ≤ − ≤ 0.30 ≤ 0.20 ≤ 0.10 ≤ 0.20 0.2
Saponification No. mg KOH/g − − ≥ 170 − − 185 – 190 − −
Ester content % mass − − ≥ 98 − − ≥ 96.5 ≥ 98 ≥ 96.5Triglyceride % mass − ≤ 0.40 − − ≤ 0.10 ≤ 0.20 ≤ 0.10 ≤ 0.20Diglyceride % mass − ≤ 0.40 − − ≤ 0.20 ≤ 0.20 ≤ 0.10 ≤ 0.20
Monoglyceride % mass − ≤ 0.80 − − ≤ 0.80 ≤ 0.80 ≤ 0.80 ≤ 0.80Free glycerol % mass ≤ 0.02 ≤ 0.02 ≤ 0.05 ≤ 0.02 ≤ 0.02 ≤ 0.02 ≤ 0.02 ≤ 0.02
Total glycerol % mass ≤ 0.24 − − ≤ 0.25 ≤ 0.25 ≤ 0.24 ≤ 0.25 ≤ 0.24
Iodine Value ≤ 120 (2) − − − ≤ 115 ≤ 115 (6) ≤ 125 ≤ 120Phosphorus ≤ ≤ mg/kg ≤ 20 ≤ 10 ≤ 10 ≤ 10 ≤ 10 (9) ≤ 20 10 10
Alkaline metals mg/kg − ≤ 5 − ≤ ≤ ≤ − 5 ≤ 10 10 5Calorific value
(net) kJ/kg − − − - − 37100 − −
Linolenic acid methyl ester % mass − − − - − − ≤ 12 −
Polyunsaturated (>4 double
bonds) methyl esters
% mass − − − - − − ≤ 1 −
26
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(1) Clear, free of separated water and solid substances at ambient temperature (2) Content of linoleic acid (C18:3) and other 3 times more unsaturated acids ≤ 15% mass (3) 10% distillation residue, 1.33 Pa (4) For ≤ 5% blends with diesel fuel (5) For ≤ 5% blends (6) For ≤ 5% blends (7) Clear and without sediment (8) No method (9) mg/L (10) Draft standard (11) For climate-dependent requirements options are given to allow for seasonal grades to be set nationally (12) The 6.0 mm2/s upper viscosity limit is higher than petrodiesel and should be taken into consideration when blending (13) 90% recovered (14) The cloud point of biodiesel is generally higher than petrodiesel and should be taken into consideration when blending (15) Other sulfur limits can apply in selected areas in the United States and in other countries
6.1 Sulfur Sulfur in biodiesel is sourced from the crops and animal fats used as feedstock. Most virgin or first use vegetable oil and animal fat based biodiesel has less than 15 ppm sulfur, however it has been found that used cooking oil can contain up to 40 ppm sulfur. This sulfur is suspected to originate from food cooked in the oil.13 Caution is also recommended for feedstock from slaughterhouse waste fats as hairs contain sulfur and will lead to higher values than 10 ppm. Many researchers claim that pure biodiesel is essentially sulfur free and that therefore biodiesel is an ultra-low sulfur fuel. Vehicle emissions and engine operability Combustion of fuel containing sulfur causes emissions of sulfur dioxide and particulate matter. Sulfurous emissions can also lead to poisoning of post-treatment devices, however this largely depends on operating conditions. Sulfur limits are generally imposed for environmental reasons. When compared with diesel fuel, Howell and Weber claim biodiesel can result in a total reduction of oxides of sulfur and sulfate aerosols in particulate matter from the tailpipe.26 Recent studies by Sharp et al confirmed that modern (American) engines running on biodiesel yielded reduced particle emissions.31 Low sulfur content has a positive influence on the lifetime of oxidation converters. Low sulfur fossil fuels have been found to cause lubricity failures in injection pumps. This is not the case when using biodiesel due to its inherent lubricity properties. International trends The European prEN 14214 biodiesel standard sets a limit for sulfur content of <10ppm (0.001 max %mass). The US ASTM D 6751 biodiesel standard sets a limit for sulfur content of <50ppm (0.005 max %mass). Test Method The European prEN 14214 standard specifies prEN ISO 20846 and prEN ISO 20884 test methods for determining sulfur content of biodiesel.29 US ASTM D 6751 prescribes test method ASTM D 5453 as the referee method for determining sulfur in biodiesel. Test methods D1266, D2622, D3120 and D4294 may be suitable for determining up to 0.05% sulfur in biodiesel fuels. Although their precision and bias is unknown, these test methods are associated with falsely high results.11 The referee testing method ASTM D 5453 for sulfur in biodiesel is not necessarily the same method required to test diesel. This is because biodiesel contains less sulfur, so a higher sensitivity is required. Seven testing methods are listed for determining sulfur in diesel under the Fuel Standards (Automotive Diesel) Determination 2001 in force under section 21 of the
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Fuel Quality Standards Act 2000, however most are less accurate than the method ASTM D 5453. Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for sulfur in biodiesel; and (b) an appropriate test method for determining the sulfur content of biodiesel.
6.2 Carbon Residue An important indicator of the quality of biodiesel is the carbon residue, which corresponds strictly to the content of glycerides, free fatty acids, soaps, remaining catalyst and other impurities.32 This parameter indicates the tendency of the fuel to form carbon deposits in an engine. Vehicle emissions and engine operability Residual carbon is deposited on injection tips and other engine components, increasing wear and impacting on engine life. Deposits also reduce fuel efficiency. Particulate emissions from diesel fuels are relatively high and mostly consist of carbon in forms of crystallites. Other species are entrained with the carbon such as PAHs, unburned hydrocarbons and nitrogen dioxide which present important environmental and health hazards. Knothe et al reported that with rapeseed methyl ester as fuel in direct-injection diesel engines, particulate matter contained large amounts of volatile and extractable compounds adsorbed on the soot. This caused particulate emissions to be higher than with diesel. However, esters from tallow feedstock were reported to generate reduced smoke emissions.33 International trends The European prEN 14214 biodiesel standard sets a limit for carbon residue (on 10% distillation residue) of <0.30% mass. The US ASTM D 6751 biodiesel standard sets a limit for carbon residue (100% distillation) of <0.05% mass. Test Method The European prEN 14214 standard specifies EN ISO 10370 test method for determining carbon residue (10% distillation). Carbon residue is an important parameter reflecting the tendency of carbonisation. The micro method EN ISO 10370 which is also included in EN590 for diesel fuel is applied on a 10% distillation residue of the sample (using ASTM D 1160).29 ASTM D 6751 prescribes test method ASTM D 4530 as the referee method for determining carbon residue in biodiesel. A 100% sample shall replace the 10%
29
residual, with percent residue in the original sample reported using the 10% residual calculation. Although biodiesel is in the distillate boiling range, most biodiesel boils at approximately the same temperature and it is difficult to leave a 10% residual upon distillation. Thus, a 100% sample is used to replace to 10% residual sample, with the calculation executed as if it were the 10% residual.11 Test methods D 189 and D 524 may also be used. Tests for the Ramsbottom carbon residue using the method ASTM D 524 are usually conducted on diesel and yield greater maximum carbon residue values with higher standard deviations for biodiesel, so are considered less suitable.34 Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for carbon residue in biodiesel; and (b) an appropriate test method for determining carbon residue of biodiesel.
6.3 Phosphorous Phosphorous content is derived from the feedstock. Although biodiesel samples produced in US have been found to have low phosphorous content (below 1 ppm), specifying phosphorous content is important for engine operability.11 This parameter was included in the ASTM D 6751 standard to prevent the de-activation of oxidation catalysts. Vehicle emissions and engine operability Phosphorous can cause damage to catalytic converters used in emissions control systems. As emissions standards are becoming more stringent, catalytic converters are becoming more common on diesel-powered equipment.11 International trends The European prEN 14214 biodiesel standard sets a limit for phosphorous of <10 ppm. The US ASTM D 6751 biodiesel standard sets a limit for phosphorous of <10 ppm (0.001 max % mass). Test Method The European prEN 14214 standard specifies prEN 14107 test method for determining phosphorous content. ASTM D 6751 prescribes test method ASTM D 4951 for determining phosphorous content in biodiesel. There is no difference in testing methods between biodiesel and diesel.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for phosphorous content in biodiesel; and (b) an appropriate test method for determining phosphorous content in biodiesel.
6.4 Ester content The main component of biodiesel and the parameter giving biodiesel similar properties to diesel is esters, or more specifically mono-alkyl esters. The total ester content is a measure of the completeness of the transesterification reaction. In general, biodiesel is defined as an alkyl ester of long chain fatty acids derived from renewable lipid sources to include esters derived from all feedstock and using an alcohol as the reagent. The major factors that affect ester yield in the transesterification reaction are:
Molar ratios of glycerides to alcohol; Type of catalyst(s) used; Reaction temperature; Reaction time; Water content; and Free fatty acid content of feedstock oils (which inhibit the desired reaction).
Other factors that affect the ester content of biodiesel to a lesser extent are:
Glycerol content of feedstock oils; Type of alcohol used in the transesterification reaction; Amount of residual catalyst; and Soap content.
Vehicle emissions and engine operability A higher conversion of feedstock oils to ester gives better engine performance. Unreacted feedstock oils, that include mono, di and triglycerides, have a high viscosity. Increased viscosity is associated with carbon deposits on fuel injector tips and reduced spray effect of fuel injection . The partially reacted glycerides also have low solubility in methyl ester and precipitate out of solution at low temperatures.35 Other impurities affecting ester concentration are free glycerol (associated with engine deposits) and alcohol residue (lowering flash point). Howell states that if specifications for impurities in biodiesel standards are adhered to ester content will be inherently over 98%.13 Testing has found yields of 95 to 99.85%, with distilled esters having a higher percent esterification than undistilled esters.34 The ester content of biodiesel can vary widely with different technologies used and feedstocks available. International trends The European prEN14214 biodiesel standard sets a minimum limit for ester content of >96.5% mass.
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The US ASTM D 6751 biodiesel standard does not set a specification for ester content. Test Method The European prEN 14214 standard specifies pr EN 14103 test method for determining ester content. Methyl ester content is commonly detected by gas chromatography. Recently, another method using viscosity measurements was found to be faster and as effective as gas chromatography.33 Diesel is not tested for ester content due to different feedstock properties.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for ester content in biodiesel; and (b) an appropriate test method for determining ester content in biodiesel. Section 6.8 -Total contamination should be referred to in conjunction with this section.
6.5 Kinematic viscosity Viscosity represents flow characteristics and the tendency of fluids to deform with stress. One of the main reasons for processing vegetable oils for use in engines is to reduce the viscosity thereby improving fuel flow characteristics. The viscosity of pure vegetable oils is 10 to 15 times greater than the viscosity of diesel. Transesterification of vegetable oils produces esters with a viscosity of approximately twice that of diesel. Esters made from ethanol are slightly more viscous than methanol based fuels.36 Viscosity is also an indicator of polymerisation of biodiesel and increases as a function of thermal and oxidative degradation.37 Vehicle emissions and engine operability Viscosity affects the flow of fuels through pipes, injection nozzles and orifices and the temperature range for proper operation of fuel in burners. High viscosities can cause injector spray pattern problems that lead to excessive coking and oil dilution. These problems are associated with reduced engine life. Minimum viscosity limits are applied to prevent fuel from causing wear in the fuel injection system, which results in loss of power. Proper viscosity provides adequate lubrication and pumping characteristics to fuel system components.38 International trends The European prEN 14214 biodiesel standard sets a limit for viscosity (40°C) of
32
3.5 – 5 mm2/s. The US ASTM D 6751 biodiesel standard sets a limit for kinematic viscosity (40°C) of 1.9 – 6.0 mm2/s. The 6.0 mm2/s upper viscosity is higher than for diesel and should be taken into consideration when blending. Blending biodiesel with diesel fuel close to its upper limit could result in a biodiesel blend with viscosity above the upper limits in specification ASTM D 975.11 Test Method The European prEN 14214 standard specifies EN ISO 3104 test method for determining viscosity at 40 °C. ASTM D 6751 prescribes test method ASTM D 445 for determining Kinematic viscosity at 40 °C. Caterpillar internal specifications were used in the ASTM D 6751 determination. Testing methods use capillary viscometers with no applied pressure for kinematic viscosity measures. The viscosity testing method recommended by ASTM is the same for both biodiesel and diesel.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for kinematic viscosity of biodiesel; and (b) an appropriate test method for determining kinematic viscosity of biodiesel.
6.6 Cetane Number The cetane number measures the readiness of a fuel to auto ignite when injected into the engine. It is also an indication of the smoothness of combustion. In a compression ignition diesel engine the cetane number is the measure of ignition promotion. In a spark ignited gasoline engine the ignition quality of gasoline is measured by the octane number which is a rating of ignition delay.39 The cetane number is not to be confused with the cetane index, which is not applicable to biodiesel. Cetane indices predict the cetane number from equations derived for petroleum distillates only. The cetane number of biodiesel depends on the distribution of fatty acids in the original oil or fat from which it was produced. The longer the fatty acid carbon chains and the more saturated the molecules, the higher the cetane number.35 Vehicle emissions and engine operability Van Gerpen et al found that the cetane number can be affected by the oxidation level of the biodiesel. This is attributed to the cetane enhancing qualities of dialkylperoxides and hydroperoxides that are formed in the oxidation process. This effect becomes minimal beyond a cetane number of approximately 70.35
33
Good ignition from a high cetane number assists in easy starting, starting at low temperature, low ignition pressures, and smooth operation with lower knocking characteristics. Low cetane fuel with poor ignition qualities causes misfiring, tarnish on pistons, engine deposits, rough operation and higher knocking (thus noise level). Exhaust emissions of white smoke increased with increasing cetane numbers.35 International trends The European prEN 14214 biodiesel standard sets a limit for cetane number of > 51. The US ASTM D 6751 biodiesel standard sets a limit for cetane number of > 47. Test Method The European prEN 14214 standard specifies EN ISO 5165 test method for determining cetane number. ASTM D 6751 prescribes test method ASTM D 613 for determining cetane number.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for the cetane number of biodiesel; and (b) an appropriate test method for determining the cetane number of biodiesel.
6.7 Sulphated Ash content Ash is formed from abrasive solids, soluble metallic soaps and unremoved catalysts remaining in the biodiesel. Combustion in the engine oxidises these materials to ash. The ash content is specified in standards either as ash (oxidated) content or sulfated ash content. There is a correlation between the sulphated ash content and the phosphorous content of the oil.32 Vehicle emissions and engine operability Ash deposits in engines and can cause clogging or filter plugging.25 Any abrasive solids or unremoved catalysts can also contribute to wear in the injector, fuel pump, piston and ring. Soluble metallic soaps have little effect on wear but may contribute to filter plugging and engine deposits.11 International trends The European prEN 14214 biodiesel standard sets a limit for sulfated ash of < 0.02 % (m/m). The US ASTM D 6751 biodiesel standard sets a limit for sulfated ash of < 0.02 % (m/m).
34
Test Method The sulfated ash content indicator is preferred over oxidate ash content for testing purposes. This ensures a more accurate measurement of sodium or potassium that could be present as residual catalyst.13 This is because the alkali sulphates have lower volatility at higher temperatures than the corresponding oxides.32 Consequently, there will not be an undue loss of material as is the case with oxides and halides of alkaline elements that evaporate at around 550oC. Instead, sulfuric acid is added and all cations are converted to sulphates (which have a higher melting and boiling point). By minimising the loss of materials, a constant weight is achieved and more accurate measurements are made. Diesel is tested for oxidate ash due to a lower accuracy required. The same oxidate ash testing method is used as for biodiesel according to those standards specifying it. The European prEN 14214 standard specifies ISO 3987 test method for determining sulfated ash content. ASTM D 6751 prescribes test method ASTM D 874 for determining sulfated ash content.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for sulfated ash content of biodiesel; and (b) an appropriate test method for determining the sulfated ash content of biodiesel. Comment is also requested on oxidated ash specifications and test methods.
6.8 Total contamination Impurities in biodiesel mostly result from the transesterification process. Leftover catalyst and unsaponifiable matter (the non-glyceridic neutral lipids, which are insoluble in water after saponification of the fat) form an important volume of contaminants, as does soap when it is formed. Non-glyceridic neutral lipids include free fatty acids, fatty alcohols, hydrocarbons, sterols, triterpene alcohols, carotinoids, and vitamins and their distribution depends on the feedstock oil used.40 Soap is formed when free fatty acids react under transesterification reaction conditions. Most of these contaminants are removed during ester washing. Vehicle emissions and engine operability Unsaponifiable matter is thought to adversely affect engine suitability in various ways including; storage properties (unsaponifiable components degrade into unfavourable materials during storage), low temperature behaviour characteristics (unsaponifiable matter generally has a higher boiling point), and other physical and chemical properties. It is likely that some of the unsaponifiable matter contributes to the formation of engine deposits as unsaponifiable components have high boiling
35
points.40 Metals remaining in soap and catalyst contaminants are converted to ash when combusted. This causes deposition on injection equipment. International trends The European prEN 14214 biodiesel standard sets a limit for total contamination of < 24 mg/kg (ppm). The US ASTM D 6751 biodiesel standard does not set a limit for total contamination. Test Method The European prEN 14214 standard specifies EN 12662 test method for determining total contamination. Further improvement of the method or a modification is necessary to get the precision required.29 ASTM D 6751 does not specify a total contamination level. This specification is not considered, so long as an alkaline catalyst is used and the biodiesel water washed, since the ash content specification will imply low contamination levels.35 However, should other methods be utilised (acid catalysts as in the case of waste oils, or other washing technology), total contamination levels should be specified. Total contamination In Australia it is known that stakeholders are planning to use acid catalysts and waste cooking oils as feedstocks, therefore the inclusion of a total contamination specification is relevant. ASTM method D 5452 uses membrane filtration to measure particles of nominal size less than 0.8 microns (filter pore size). Unsaponifiable matter can be determined by extraction using a nonpolar organic solvent such as diethylether and drying at 103oC. The non-volatile residue is measured. Total contamination is not specified under the Fuel Standard (Automotive Diesel) Determination 2001 for diesel.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for total contamination of biodiesel; and (b) an appropriate test method for determining total contamination of biodiesel.
6.9 Acid value The total acid number (TAN) is an indication of the presence of free fatty acids or acids formed due to oil degradation and combustion (during or following processing). Acidity can also result from improper manufacturing, through remaining catalyst (if manufactured in acidic conditions) or excessive neutralisation. This is different for diesel, which does not contain these materials.41
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Vehicle emissions and engine operability The acid number represents the amount of base required to neutralise the sample of biodiesel. It is expressed in terms of mass of KOH required per mass of sample. Further to this, the total base number (TBN) or alkaline number indicates the ability of the lubricant to neutralise acid compounds generated by combustion and degradation of the oil. Either the TAN or the TBN are determined from testing. If the acid value exceeds 0.10 mg KOH/g, fuel system deposits and reduced pump and filter life may result.25 New fuel systems that operate at higher recycle temperatures may accelerate fuel degradation which could result in high acid values and increased filter plugging potential.11 Testing has found that biodiesel increases the acidity of the lubricating engine oil.41 It was also found that the TBN in used lubricating engine oil (samples taken after 440 and 630 working hours) reached excessively low values when biodiesel was used as a fuel. Acid number is also associated with corrosion. The TBN does not appear to be affected by polymerisation.42 International trends The European prEN 14214 biodiesel standard sets a limit for acid value of < 0.5 mgKOH/g. The US ASTM D 6751 biodiesel standard sets a limit for acid number of < 0.80 mgKOH/g. The ASTM D 6751 specified acid number is based on use up to B20 and based on 1000 hour pump stand durability testing. It may be necessary to adapt this limit for blends of greater than 20%. Alkalinity is specified in the DIN 51606 standards (but not in ASTM D 6751) as less than 5 mg/kg. Neutralisation number, acid value and acidity are interchanged on standards tables. Caterpillar expressed the acid value recommended for biodiesel in terms of mg NaOH/g, though the US standard specifies acid value in terms of mg KOH/g. Test Method The European prEN 14214 standard specifies prEN 14104 test method for determining acid value. ASTM D 6751 prescribes test method ASTM D 664 as the referee method for determining acid number. Test methods D 3242 or D 974 may also be used.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for acid value/number of biodiesel; and (b) an appropriate test method for determining acid value/number of biodiesel.
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6.10 Iodine number The iodine number is an index of the number of double bonds in biodiesel, and therefore is a parameter that quantifies the degree of unsaturation of biodiesel. The iodine number is reported in terms of the grams of iodine that will react with 100 g of fat or oil under specified conditions. Vehicle emissions and engine operability Biodiesel viscosity is directly correlated to the iodine number of biodiesel for biodiesel with iodine numbers of between 107 and 150.43 Saturation of fats is linked to the cetane number. At high saturation, the cetane number is improved and engine operability is improved. However high saturation increases the iodine number which gives poor low temperature qualities. Therefore a balance is needed between the cetane number and the iodine value of biodiesel. Observations by Knothe33 and Mittelbach32 identified the amount of higher unsaturated fatty acids as a more important factor than the iodine number as an indication of fuel quality. In the US, the iodine number is considered to be a poor indication of fuel stability. This is because there is no correlation if feedstocks are blended, or if natural or added anti-oxidants or storage enhancers are present.13 A limitation of unsaturated fatty acids may be necessary, due to the fact that heating higher unsaturated fatty acids results in polymerisation of glycerides. This can lead to the formation of deposits or to deterioration of the lubricating oil. This effect increases with the number of double bonds in the fatty acid chain. It has been proposed that biodiesel with an iodine value of above 115 increased the risk of polymerisation in the engine.44 International trends The European prEN 14214 biodiesel standard sets a limit for iodine value of < 120. The fatty acid profile of the raw feedstock material defines the properties of the fuel. In Europe engine manufacturers have been aware of the iodine number which expresses the number of double bonds. Rapeseed oil has a iodine value of 115-120, sunflower oil about 130-135.29 One of the political drivers behind DIN 51606 was the desire to limit soybean oil imports into Germany, therefore the iodine number test was set as a specification. This effectively limits the choice of feedstock to canola. An Australian standard would ideally not have an iodine number specification, in order to include non-canola feedstocks for biodiesel production. The US ASTM D 6751 biodiesel standard does not set a limit for iodine value. Test Method The European prEN 14214 standard specifies prEN 14111 test method for determining iodine value.
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A number of different testing methods exist for determination of iodine value. The iodine number is sensitive to time of contact, the nature of the iodine carrier and excess of iodine so it is necessary whilst testing to strictly adhere to the specific conditions. This parameter is not relevant to diesel due to different feedstock. Some biodiesel producers have voiced concerns about the application of DIN 51606 due to the high iodine value that restricts the use of different feedstocks. Knothe et al33 highlighted a number of reasons why the iodine number should not be included in biodiesel standards. Recommendations by Caterpillar require a maximum iodine number of 110 cg I2/g, to be determined by the testing methods DIN 53241 or IP 84/81. This is lower than the 115 cg I2/g recommended by the DIN 51606 standard. The latter value corresponds to rapeseed oil but excludes biodiesel production from different kinds of oils, such as sunflower oil and soybean oil.32
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for iodine value/number for biodiesel; and (b) an appropriate test method for determining iodine value/number for biodiesel. Note: Iodine number is of particular interest in the Australian context as it is known that stakeholders intend on using a variety of feedstocks to produce biodiesel.
6.11 Linoleic acid methyl ester and polyunsaturated methyl esters (>4 double bonds) Sunflower, soy, cottonseed and maize oils contain a high proportion of linoleic fatty acids. These are highly unsaturated with a C18:2 (single:double C bonds) configuration. This affects the properties of the derived ester with a low melting point and cetane number. The high degree of unsaturation (up to 80%) in linoleic acids is also associated with high iodine number.45 They combine readily with hydrogen and other substances such as oxygen and iodine and therefore, their presence is indicated in the iodine number.46 Vehicle emissions and engine operability A limitation of unsaturated fatty acids may be necessary, due to the fact that heating higher unsaturated fatty acids results in polymerisation of glycerides. This can lead to the formation of deposits or to deterioration of the lubricating oil. This effect increases with the number of double bonds in the fatty acid chain and therefore will be high for linoleic acid methyl ester. Mittelbach32 suggests that it is better to limit the content of higher unsaturated fatty acids than to limit the degree of unsaturation with the iodine number.
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Fatty acid molecules are said to be unsaturated if they do not contain the maximum hydrogen possible. This implies the presence of double bonds, which decrease fuel quality.33 The position of the double bonds is also relevant, as double bonds on the end of molecules enhance the cetane number of the fuel. Lipoxidase is a naturally occurring powerful oxidation catalyst that occurs in various plant oils. Lipoxidase reacts with methylene interrupted bond systems in the cis configuration of unsaturated fatty acids (and esters). Lipoxidase increases the rate of oxidation, as the activation energy required to start the oxidation reaction is much lower than other possible oxidation reactions.42 Therefore, the presence of linoleic acid methyl ester in biodiesel increases the rate of biodiesel polymerisation adversely affecting engine operability. Polymerisation can also occur in the engine lubricating oil if the fuel passes into the engine crankcase.42 This causes the lubricating oil to thicken and become less effective. Linolenic acid methyl ester National standards in Europe and the European standard, prEN 14214, limit the content of linolenic acid methyl ester and high unsaturated acids. Linolenic acid is similar in properties (though less saturated and therefore more prone to deposit formation) to linoleic acid methyl ester.
International trends The European prEN 14214 biodiesel standard sets a limit for linolenic acid methyl ester content of < 12 % (m/m). The prEN 14214 biodiesel standard also sets a limit on polyunsaturated (> 4 double bonds) methyl ester content of < 1% (m/m). The US ASTM D 6751 biodiesel standard does not set a limit for linolenic acid methyl ester content or polyunsaturated (> 4 double bonds) methyl ester content. Test Method The European prEN 14214 standard specifies prEN 14103 test method for determining linolenic acid methyl ester. There is no method to determine fatty acids >4 double bonds at such low limits.29 Fatty acid distribution can be determined by DGF methods C-IV 10a (81), DGF Methods C-VI 11a (81) and A.O.C.S. official methods CEC 1-62. These methods apply to methyl esters of fatty acids having 8 to 24 carbon atoms and permit quantitative separation of mixtures containing saturated and unsaturated methyl esters. This parameter is not relevant to diesel due to different feedstock.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for linolenic acid methyl ester content in biodiesel; (b) an appropriate test method for determining linolenic acid methyl ester content in biodiesel; (c) an appropriate Australian specification for polyunsaturated (> 4 double bonds) methyl ester content in biodiesel; and (d) an appropriate test method for determining polyunsaturated (> 4 double bonds) methyl ester content in biodiesel.
6.12 Mono- and Di-Glycerides Mono- and di-glycerides as well as tri-glycerides are referred to as bound glycerin. They are present in the feedstock oil and can remain in the final product in small quantities. Most are generally reacted or concentrated in the glycerin phase and separated from the ester.35 Vehicle emissions and engine operability Bound glycerin is associated with carbon deposits on fuel injector tips and piston rings. Furthermore, monoglycerides have high melting points and a low solubility in methyl esters and require high temperatures to prevent them from crystallizing out of solution.35 However, it appears from testing that diglycerides counter the crystallization effects of monoglycerides. Van Gerpen35 found that the viscosity of the ester increases slightly with increasing monoglycerides content, however this is not expected to have adverse affects on the engine operability. When monoglycerides are considered alone, it appears that crystals will form even at saturated monoglyceride concentrations as low as 0.05%. This should raise the cloud point of the fuel by 2-3°C which would probably not create any problems but should not be exceeded. In the presence of diglycerides, however, crystallization was found to be inhibited and no change to the cloud point was recorded. However, since this phenomena relies on the ratio of mono to di-glycerides, no change should be made to the specifications without closer analysis of the relationship between the two.35 International trends The European prEN 14214 biodiesel standard sets a limit for monoglyceride content of < 0.8 % (m/m) and a diglyceride content of < 0.2 % (m/m). The US ASTM D 6751 biodiesel standard does not set a limit for monoglyceride or diglyceride content.
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Test Method The European prEN 14214 standard specifies prEN 14105 test method for determining both monoglyceride and diglyceride content. ASTM D 6584 or DIN 51609, both identifying the parameter through gas chromatography, can be used for this specification. This parameter is not relevant for diesel due to differences in feedstock.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for mono- and diglyceride content in biodiesel; and (b) an appropriate test method for determining mono- and digylceride content in biodiesel.
6.13 Triglyceride content One of the main reasons for treating vegetable and animal oils for use in diesel engines is the high viscosity of triglycerides (the major component of vegetable and animal oils) and the associated engine durability issues.33 A high excess of alcohol in the transesterification reaction should ensure all triglycerides are reacted. They are generally grouped with mono and di-glycerides as bound glycerin. Vehicle emissions and engine operability A higher content of glycerides, especially triglycerides, may cause formation of deposits at the injection nozzles, at the piston and at the valves.32 International trends The European prEN 14214 biodiesel standard sets a limit for triglyceride content of < 0.2 % (m/m). The US ASTM D 6751 biodiesel standard does not set a limit for triglyceride content. Test Method The European prEN 14214 standard specifies prEN 14105 test method for determining triglyceride content. Triglycerides are limited with mono- and di-glycerides as total glycerin. Free and total glycerin are detected by gas chromatography according to ASTM standard testing method. This parameter is not relevant for diesel due to differences in feedstock.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for triglyceride content in biodiesel; and (b) an appropriate test method for determining trigylceride content in biodiesel.
6.14 Free Glycerol Free glycerol (or glycerin) is a by-product of the transesterification process and is separated during processing from the ester and sold as a by product. However, some free glycerol can remain in the ester due to inefficient separation or insufficient ester washing following separation. Glycerol is more soluble in water than it is in biodiesel, so if any free water is present in the biodiesel there will usually be a low free glycerol content of the ester phase. Saturation with water will increase the glycerol content only slightly.35 Vehicle emissions and engine operability A higher content of free glycerol may cause problems during storage or in the fuel system due to separation of glycerol, or can lead to injector fouling or the formation of higher aldehyde emissions. It is associated with deposits in engines as it collects in the bottom of fuel tanks and attracts other compounds such as water and monoglycerides.35 If the ester is saturated with dissolved water, there can be up to 0.187% glycerol present. Despite this, the ASTM and DIN standards of 0.02% are achievable through proper separation and washing. Since the major issue with free glycerin are its accumulation in a separated phase, it has been proposed that these standards could be relaxed to, for example, 0.05%.35 This would allow for alternative ester cleaning techniques to the traditional washing method.32 International trends The European prEN 14214 biodiesel standard sets a limit for free glycerol content of < 0.02 % (m/m). The US ASTM D 6751 biodiesel standard sets a limit for free glycerin content of < 0.02 % (m/m). Test Method The European prEN 14214 standard specifies prEN 14105 and prEN14106 test methods for determining free glycerol content. ASTM D 6751 prescribes test method ASTM D 6584 for determining free glycerin content.
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This parameter is not relevant for diesel due to differences in feedstock and processing.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for free glycerol content in biodiesel; and (b) an appropriate test method for determining free glycerol content in biodiesel.
6.15 Total Glycerol Glycerol (or glycerin) is a by-product of the transesterification reaction and is separated from the ester product for other industrial applications. Total glycerol is the sum of free glycerol and bound glycerol, where bound glycerol is the content of mono, di and triglycerides. The total glycerol content mainly depend on the processing techniques employed and are one of the main parameters indicating the final quality of biodiesel.32 Low levels of total glycerin ensure that high conversion of the oil or fat into its mono-alkyl esters has taken place.11 Vehicle emissions and engine operability High levels of mon-, di-, and triglycerides can cause injector deposits and may adversely affect cold weather operation and filter plugging.11 International trends The European prEN 14214 biodiesel standard sets a limit for total glycerol content of < 0.25 % (m/m). The US ASTM D 6751 biodiesel standard sets a limit for total glycerin content of < 0.24 % (m/m). Test Method The European prEN 14214 standard specifies prEN 14105 test method for determining total glycerol content. ASTM D 6751 prescribes test method ASTM D 6584 for determining total glycerin content. This parameter is not relevant for diesel due to differences in feedstock and processing.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for total glycerol content in biodiesel; and (b) an appropriate test method for determining total glycerol content in biodiesel.
6.16 Alkaline metals Alkaline metals result from the metal catalyst used in transesterification. Typical catalysts used are sodium methoxide, sodium hydroxide and potassium hydroxide. The alkaline metals content is essentially controlled by the sulphated ash test. Therefore, potentially only one of these tests is necessary.13 Vehicle emissions and engine operability Metals are linked with ash formation in the combustion engine.35 Furthermore, certain metals are known catalysts of ester polymerisation, amongst which cobalt, lead, manganese and copper are very strong and chromium, tin and calcium rate strongly.33 International trends The European prEN 14214 biodiesel standard sets a limit for Group I metals (Na, K) content of < 5 mg/kg and Group II metals (Ca, Mg) content of < 5 mg/kg. The US ASTM D 6751 biodiesel standard does not set a limit for alkaline metal content. Test Method The European prEN 14214 standard specifies prEN 14108 and prEN 14109 test methods for determining Group I metals and prEN 14538 for Group II metals. This parameter is not relevant for diesel due to differences in processing.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for alkaline metal content in biodiesel; and (b) an appropriate test method for determining alkaline metal content in biodiesel.
Biodiesel Parameters Affecting Stability The deterioration of vegetable oil derivatives is associated with hydrolytic and oxidative reactions. This is dependent on the degree of unsaturation that makes them
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susceptible to thermal and/or oxidative polymerisation.48 Natural antioxidants such as Vitamin E (tocopherol) contained in the vegetable oils inhibit this reaction.35 Oxidation of biodiesel results in the formation of hydroperoxides. The formation of the hydroperoxide follows a well known peroxidation chain mechanism. Further oxidation of peroxides generates aldehydes and short chain acids. As in diesel, a major concern of users and sellers of biodiesel is chemical attack of fuel system components.50 Reaction rates depend on hydrocarbon structure, heteroatom concentration and speciation, oxygen concentration and temperature. Furthermore, catalysts and free radical inhibitors can alter the rate and pathway of the reaction.51 Biodiesel that has been distilled generally contains fewer natural antioxidants, as they are removed with the distillation residue. The frying of vegetable oils consumes most of the antioxidants, so it can be assumed that biodiesel made from used frying oil has a poor oxidative stability.48 Degradation is often accompanied by a degradation of colour which is primarily a marketing concern.50 The extent of degradation depends on the degree of unsaturation. The main impacts on fuel of oxidation are the formation of insolubles (particularly in copper or copper containing metals storage environments) and an increased acid number and viscosity. Data thus far collected on testing suggests the acid number reaches upper specifications before other parameters.37 These changes can give rise to sediment and gum formation and fuel darkening. These product characteristics can cause filter plugging, injector fouling, depositions in the engine combustion chamber, and malfunctions in various components of the fuel system. In past engine tests with biodiesel fuel, instability appeared to contribute to malfunctions of fuel system and engine components.50 However, it does not appear that the oxidation level, or the peroxide value, affects exhaust emissions.35 Caterpillar52 harbours concerns about the oxidation of biodiesel in storage. They found that biodiesel oxidation is of significant concern in electronic fuel systems that operate at elevated temperatures and consequently recommend the use of oxidation stability additives. A review of a great number of stability tests found that the two general categories were tests conducted at 43oC over a long-term period, and high temperature or pressure tests over a shorter period. The former category demonstrates oxidative degradation and requires up to 24 weeks to perform and is therefore impractical for process and quality control.50 Biodiesel stability tests differ from diesel tests because the mechanisms for change are not the same in the two fuels. The main focus in vegetable oil testing so far has been on the onset of rancidity, which may or may not have anything to do with performance as a diesel fuel.37
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6.17 Thermal Stability Thermal degradation occurs at high temperatures and degrades hyperperoxide in the fuel more rapidly than oxidative degradation.33 This can occur in non-oxidizing atmospheres. Fuel is subject to high temperature environments in or near the engine (and particularly at the injectors), when fuel reaches temperatures of 150oC for short periods of time. Elevated temperatures of 60 to 70oC are also reached in the fuel systems. Biodiesel and biodiesel blends are much more thermally stable than diesel.37 International trends The European prEN 14214 biodiesel standard does not set a limit for thermal stability. The US ASTM D 6751 biodiesel standard does not set a limit for thermal stability. Test Method Shorter-term tests are not held to provide reliable degradation data however it is possible a good correlation could be developed for individual refiners using these methods. Some short-term methods for thermal stability are Du Pont F21 and its modified version, the ASTM 150oC high temperature method ASTM D 6468, an oxygen overpressure method analysed using ASTM D 381 or D525.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for biodiesel thermal stability; and (b) an appropriate test method for determining thermal stability in biodiesel.
6.18 Oxidation Stability The presence of dissolved oxygen or active oxygen species greatly increases the oxidation potential of the fuel and lowers the temperature at which degradation occurs.51 International trends The European prEN 14214 biodiesel standard sets a limit for oxidation stability (110
oC) of > 6 hours.
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Oxidation stability There is little experience on the effects of a low stability of biodiesel on engines or boilers so far. ‘Stability’ can be defined in terms of oxidation, thermal and storage stability. For this reason the project titled “Stability of Biodiesel” (BIOSTAB) funded by the European Community started in 2001. Nine experienced European partners are involved under the leadership of BLT Austria (the Federal Institute for Agricultural Engineering). The objective of the project is to establish clear criteria and the corresponding analytical methods to determine the stability of biodiesel. The working programme covers investigation on determination methods, storage, antioxidants and tests with both, engines and heating systems. (Source: Prankl, 2002)
The US ASTM D 6751 biodiesel standard does not set a limit for oxidation stability. Test method The European prEN 14214 standard specifies prEN 14112 (Rancimat) test method for determining oxidation stability. Prankl and Schindlbauer53 found that the oxidation stability is closely related to the viscosity and acid number. Using the Ranchman testing method, it was determined that the viscosity decreases markedly during the induction period and the acid number decreases to a lesser extent. Similar correlations were found for the Conradson Carbon Residue. In storage conditions, light was found to contribute only mildly to oxidative stability even at high temperature conditions. Knothe et al33 also found that methyl esters were more stable than ethyl esters in storage. Storage materials were identified as a parameter affecting the oxidative degradation of the esters. For example, when stored in glass, a high concentration of primary oxidative products was observed, as compared with storage in the presence of iron where more secondary oxidative products were generated.33 It has been found that polymerisation can also be affected by the presence of a natural oxidation catalyst, lipoxidase.42 This chemical is a naturally occurring enzyme that acts as an oxidation catalyst, promoting polymerisation, in various oil plants (especially soybean). Although a great number of short and long term tests have been determined, ASTM were unable to come to a consensus on a satisfactory short term testing method in diesel specifications. In general, higher test temperatures give results which are not entirely indicative of long term storage stability.37 A literature evaluation of testing methods found modifications of the ASTM D 2274 (accelerated method) and the ASTM D 4625 (43oC long term storage) method may provide accurate and reliable information on oxidative stability for biodiesel and biodiesel blends.
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The testing method ASTM D 4625 is a long term testing method that correlates best with actual petroleum storage experience. A known volume of fuel is stored in an oven for 4 to 12 weeks at approximately 43oC. The fuel is then filtered and insoluble matter is measured. Although this is clearly impractical for processing purposes, this method is used as a benchmark against which short-term tests may be compared.50 The ASTM D 2274 accelerated method appears to be the most useful if correlated with ASTM D 4625 data.37 Modifications made may vary between pure biodiesel and biodiesel blends. In tests determining the influence of parameters and processing technology on oxidative stability, Mittelbach & Gangl48 used a standard testing method from the British Standards Institution (BSI) of London. The procedure IP 306 involves passing air through a biodiesel sample heated to 110oC and then passing it through a water solution. The conductivity of the water solution is measured. During an initial heating period known as the induction period, the natural antioxidants are consumed. Following this, the formation of volatile acidic organic compounds increases conductivity and the amount of natural antioxidants that were present can be measured. This was also used by Prankl and Schindlbauer53 and is referred to as the Ranchman method. In this case, 10 L/h air was passed through 10 g samples at 95oC, 110oC and 120oC. Fuel Injection Equipment Manufacturers54 advocate a modified IP 306 procedure, which is currently being evaluated for European biodiesel specification. Current experience shows, even for the best of fatty acid methyl esters, a maximum induction period of four hours exists. This is considered low and FIE manufacturers anticipate additives will be necessary to regulate this parameter. The methods ASTM D 2274 and IP 306 (modified) are recommended by Caterpillar, for a maximum oxidation stability of 15 mg/100mL.52 The oxidation level is also linked to the cetane number. Van Gerpen et al35 believe that biodiesel standards should include a measure of the biodiesel tendency to oxidize as well as the current level of oxidation. The former could be indicated by the iodine number, or a variation of an ASTM fuel stability test such as D 2274. The peroxide value (PV) is an indication of the current level of oxidation for which a maximum limit is set. It is believed a PV of 70 may be appropriate since this is the level beyond which the cetane number does not increase. Further increases beyond this level should have only deleterious effects. The PV can be measured by ASTM D 3703.42 Diesel is measured for oxidative stability with the ASTM D 2274 method. This is similar to the recommended biodiesel method, though lacks the modifications required for biodiesel-specific properties (such as filtration requirements). New stability parameters for biodiesel will be published upon conclusion of the BIOSTAB project as coordinated by BLT-Austria by early 2003. The BIOSTAB project team were approached but they were not able to release any preliminary findings to Pacific Air & Environment before the completion of their final report.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for oxidation stability in biodiesel; and (b) an appropriate test method for determining oxidation stability in biodiesel.
6.19 Alcohol Content Methanol and ethanol are commonly used in the production of biodiesel. Alcohol left over from the transesterification reaction can be found in the final product in small quantities. It has a low flashpoint that can affect the overall flashpoint of the biodiesel fuel. The flash point is the temperature at which the fuel will ignite when sparked. The ASTM D 6751 specifications limit the flashpoint to a minimum of 130°C, which is well above the limits for diesel fuels. If the flashpoint is already specified, this test becomes redundant.13 Vehicle emissions and engine operability High concentrations (>5%) of methanol will impact on cetane number and fuel lubricity and will lower the flash point.35 Low flashpoints are associated with safety issues both in storage and in the engine itself. Free methanol is also associated with corrosion of aluminium and zinc in the fuel injection engine.54 International trends The European prEN 14214 biodiesel standard sets a limit for methanol content of < 0.20 % (m/m). The US ASTM D 6751 biodiesel standard does not set a limit for alcohol content as flashpoint is seen as a check for this. Test method The European prEN 14214 standard specifies prEN 14110 test method for determining methanol content. Caterpillar recommends gas chromatography and DIN 51608 as testing methods for methanol content for a maximum of 0.2% (mass basis).52 The DIN 51606 standard limits methanol to 0.3% (mass basis). This parameter is not relevant to diesel due to the difference in processing.
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Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for alcohol content in biodiesel; and (b) an appropriate test method for determining alcohol content in biodiesel. Section 7 provides further detailed information on alcohol.
6.20 Cloud Point The cloud point of a clear distillate fuel is the temperature at which the fuel becomes hazy or cloudy due to the appearance of wax crystals. Compliance with this parameter ensures that the fuel is suitable for use in ambient temperatures down to -15oC without heating the fuel. In relation to biodiesel, the cloud points of ethyl esters are slightly lower than those of methyl esters. The cloud point also varies with feedstock. Vehicle emissions and engine operability Dunn and Bagby55 found a linear correlation between the cloud point and the cold filter plug point and that biodiesel tends to have a higher cloud point than diesel fuel. For this reason, it is unlikely that cloud point standards set for diesel fuel (as per AS 3570 – Australian standard - Automotive diesel fuel) would be met by biodiesel in all seasons. Biodiesel fuels may pose storage and operability problems at low ambient temperatures. If suitable precautions are not taken, such as heating fuel lines, filters and tanks, it is possible that the filters will plug and fuel in the tank may solidify at low ambient temperatures.52 International trends The European prEN 14214 biodiesel standard does not set a limit for cloud point. The US ASTM D 6751 biodiesel standard does not set a limit for cloud point however the standard states that the cloud point of biodiesel is generally higher than diesel and should be taken into consideration when blending. The cold filter plug point is considered a more accurate test of biodiesel cold weather performance.25 Test Method Although ASTM D 6751 does not set a limit on cloud point the standard does recommend ASTM D 2500 as the referee method for determining cloud point if the test is required. The standard also states that test method D 3117 may also be used because the two are closely related. The precision and bias of these test methods for biodiesel is not known and is currently under investigation.11 Research suggests that ASTM D 883 can also be used.
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When testing for cloud point samples are cooled under controlled laboratory conditions and the temperature at which a cloud of wax crystals first appears is noted. Dunn and Bagby55 proposed that thermal analyses are a better indicator of cloud point than the ASTM method D2500 for methyl esters. In the latter, a visual detection of haziness is required which leads to subjectivity in the results. However, Differential Scanning Calorimetry (DSC) curves can be used to infer a cloud point that minimizes experimental error in visual detection. DSC also provides useful information on nucleation, crystallisation and polymorphism. Cummins recommends the test method ISO 3015, and specifies a temperature of 6oC below the lowest ambient temperature at which the fuel is expected to operate. Diesel has a naturally low cloud point compared with biodiesel. There is no recommended standard, and therefore no testing method, for diesel cloud point under the Fuel Standards (Automotive Diesel) Determination 2001 standards.
Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for cloud point in biodiesel; and (b) an appropriate test method for determining cloud point in biodiesel.
6.21 Cold Filter Plugging Point The cold filter plugging point is the temperature at which wax crystals precipitate out of the fuel and plug equipment filters. At temperatures above this point, the fuel should give trouble free flow. The cold filter plugging point shows nearly linear dependence with respect to cloud point and is a good indicator of operability limits.55 As with the cloud point, the cold filter plugging point is unlikely to satisfy diesel fuel standards (AS 3570) in all seasons. Vehicle emissions and engine operability Operability and storage problems may arise from a high cold filter plugging point, with filter plugging and solidification of fuel in the tank.52 International trends The European prEN 14214 biodiesel standard sets indicative limits for cold filter plugging point. These limits are to be decided by each EU member state according to its climate conditions. The US ASTM D 6751 biodiesel standard does not set a limit for cold filter plugging point. It is considered impractical to specify cold flow limits necessary for proper operation for all geographies and times of the year. Under the ASTM D 975 testing specifications, there are tables identifying the 10 percentile minimum temperature by month in the US that is used as a guideline for determining this parameter. However,
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it is usually managed by the supplier and customer in the US. Furthermore, for biodiesel used as a blend, a higher freezing diesel is acceptable.13 For this reason, ASTM D 6751 does not specify this parameter. Test method The European prEN 14214 standard specifies EN 116 test method for determining cold filter plugging point. The engine manufacturer Caterpillar recommend the use of the testing methods ASTM D 4539 and DIN EN 116 (International method). The recommended maximum temperatures are 6oC in summer and 0oC in winter. There is no specified cold filter plugging point for diesel and no accompanying testing method under the Fuel Standards (Automotive Diesel) Determination 2001.
Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for cold filter plugging point of diesel; and (b) an appropriate test method for determining the cold filter plugging point of biodiesel.
6.22 Distillation Temperature The distillation range can be used to find the calculated cetane index (CCI). The correlation requires the 10, 50 and 90 % distillation temperatures and specific gravity. Distillation gives an indication of the presence of components of different boiling points and other contaminants. Biodiesel is composed of relatively few compounds compared with diesel, most of which are C16 to C18 carbon chain length alkyl esters. These boil at roughly the same temperature, so the distillation temperature is more representative of a boiling point. Furthermore, this boiling point does not vary widely between biodiesel made of different feedstocks, as the composition of naturally occurring oils and fats are similar.11 Vehicle emissions and engine operability The presence of high boiling point components influences solid deposit formation. Boiling point ranges also indicate the flash point and cold flow properties of the fuel. These have safety and storage implications. International trends The European prEN 14214 biodiesel standard does not set a limit for distillation temperature.
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The US ASTM D 6751 biodiesel standard sets a limit for distillation temperature (atmospheric equivalent temperature, 90% recovered) of 360 oC max. Prior discussion on whether to include the distillation temperature hypothesised that it may be exclusionary for certain feedstocks or processes. The distillation curve of biodiesel is very small and properties are better represented by the boiling point. However, this specification was incorporated as an added precaution to ensure the fuel has not been adulterated with high boiling contaminants.11 Test method ASTM D 6751 prescribes test method ASTM D 1160 (distillation temperature, reduced pressure) for determining distillation temperature. This test method has previously been criticised on its precision and repeatability.56 Due to the similar boiling points of biodiesel, it is recommended to conduct distillation tests only on a 100% sample basis.11 This is because biodiesel boils off at the same temperature, unlike diesel that has a distinct distillation curve. Diesel is tested to 95%, with 5% residue using methods ASTM D 86 or D 2887.
Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for distillation temperature of biodiesel; and (b) an appropriate test method for determining the distillation temperature of biodiesel.
6.23 Calorific Value The calorific value or heat of combustion of fatty compounds determines the amount of energy generated by the fuel. This parameter varies with different feedstocks, with similar compounds (containing similar long-chain, unbranched alkanes) having similar heats of combustion. Vehicle emissions and engine operability The heat content of biodiesel is almost 90% of the heat content of diesel.33 This reduces the fuel efficiency and counters the effect of increased density of biodiesel. International trends The European prEN 14214 biodiesel standard does not set a limit for calorific value. The US ASTM D 6751 biodiesel standard does not set a limit for calorific value. Test method No calorific testing method was identified for biodiesel. The hydrocarbon fuel bomb calorimeter method is ASTM D 4809.
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Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for biodiesel calorific value; and (b) an appropriate test method for determining biodiesel calorific value. Section 6.24 – Density should be referred to when making comment on this section.
Biodiesel parameters that affect other properties
6.24 Density Biodiesel is generally more dense than diesel fuel with sample values ranging between 877 kg/m3 (tallow methyl ester) to 884 kg/m3 (soy methyl ester) compared with diesel at 835 kg/m3.1 Thus, density of the final product depends mostly on the feedstock used. The transesterification process has been found in some cases to reduce fuel density.57 Lower density contaminants such as methanol and ethanol also decrease overall density of the fuel. Vehicle emissions and engine operability Density is an important design parameter for diesel fuel injection systems and is an area where higher blends of biodiesel are different from diesel. Howell states, that if other specifications are met, this parameter is made redundant.13 Density dictates the energy content of fuel where high densities indicate more thermal energy for the same amount of fuel and therefore better fuel economy. Although biodiesel is more dense than diesel, its energy content is lower so fuel economy overall is reduced. International trends The European prEN 14214 biodiesel standard sets a limit for density at 15oC of 860 - 900 kg/m3. The US ASTM D 6751 biodiesel standard does not set a limit for density. The standard states that the density of biodiesel, when meeting all other specifications, falls between 860 and 900, with typical values falling between 880 and 890. Since biodiesel density falls between 860 and 900, a separate specification is not needed. The density of raw oils and fats is similar to biodiesel, therefore use of density as an expedient check of fuel quality may not be as useful for biodiesel as it is for diesel.11 Test method The European prEN 14214 standard specifies EN ISO 3675 and EN ISO 12185 test methods for determining density.
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Testing is also conducted using a hydrometer according to the ASTM D 1298 and DIN 3675 methods. The density testing method recommended by ASTM is the same for both biodiesel and diesel. Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for biodiesel density; and (b) an appropriate test method for determining biodiesel density. Section 6.23 – Calorific Value should be referred to when making comment on this section.
6.25 Flash Point The flash point is the lowest temperature (corrected to barometric pressure) at which contact with a flame causes the vapour of the fuel specimen to ignite under specified conditions.58 Flash points for biodiesel are approximately twice those of diesel. Furthermore, the flash point of methyl ester fuels is higher than that of ethyl esters. Examples of the ranges in flashpoint for biodiesel samples include between 160oC for tallow methyl esters to 188oC for soy methyl esters.58 Vehicle emissions and engine operability The flash point determines the flammability of the material. Generally, the flash point is set relatively high for safety and transport reasons and also to ensure that manufacturers remove sufficient alcohol from the process. Residual alcohol reduces the flash point of biodiesel and can result in poor combustion properties. High flash points are particularly important in niche applications such as underground mining. Low flash points can indicate alcohol residue in the biodiesel. A methanol content of around 0.2% can lead to a flash point of below 100oC. To maintain the flash point above 55oC, a methanol content of less than 0.4% must be achieved.40 International trends The European prEN 14214 biodiesel standard sets a limit for flash point of 120oC min. The US ASTM D 6751 biodiesel standard sets a limit for flash point (closed cup) of 130.0oC min. The flash point for biodiesel is used as the mechanism to limit the level of unreacted alcohol remaining in the finished fuel.11 Test method The European prEN 14214 standard specifies ISO/DIS 3679 test method for determining flashpoint. ASTM D 6751 prescribes test method ASTM D 93 for determining flashpoint.
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ASTM state that the flash point specification for biodiesel is intended to be 100oC minimum. Typical values are over 160oC. Due to high variability with Test Method D 93 as the flash point approaches 100oC, the flash point specification has been set at 130oC minimum to ensure an actual value of 100oC minimum. Improvements and alternatives to Test Method D 93 are being investigated. Once complete, the specification of 100oC minimum may be re-evaluated.11 The method ASTM D 93 is recommended, though the methods ASTM D 3828 and D6450 are also acceptable. The latter methods are still under investigation for precision and bias. ASTM D 93 is also used in testing diesel. Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for biodiesel flash point; and (b) an appropriate test method for determining the flash point of biodiesel.
6.26 Dissolved Water Content Water can occur either dissolved in the fuel or as free water. It is more prevalent in biodiesel fuels than in distillate fuels.52 The amount of water in the fuel depends on its solubility and can accumulate from humid air entering storage areas through vents and seals.35 Solubility increases with increasing temperature. Vehicle emissions and engine operability Dissolved water can cause a reversion of fatty acid methyl esters to fatty acids, which leads to filter plugging.54 Free water causes many problems in engines that are generally not applicable to dissolved water. For example, dissolved water is not available for microbial growth (unlike free water, discussed with sediment in section 6.27) and this partly justifies the higher content when compared with diesel fuel.35 Furthermore, dissolved water does not pool as a separate phase in the fuel. During storage, rapeseed oil methyl ester can absorb up to 1000 ppm of water. Therefore, limiting water content to lower than this appears unreasonable. When a 0.2% (mass basis) methanol content is considered, the maximum concentration of soluble water increases to 1500 ppm.32 Standards often specify water and impurities separately, however some consider ‘water and sediment’ together. Diesel is tested in this manner. International trends The European prEN 14214 biodiesel standard does not set a limit for dissolved water content. The US ASTM D 6751 biodiesel standard does not set a limit for dissolved water content.
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Test methods Test methods that can be used are ASTM D 1796 and DIN 51777-1/ISO 3733 using distillation. Stakeholders are specifically requested to provide comment on: (a) if needed, an appropriate Australian specification for dissolved water content in biodiesel; and (b) an appropriate test method for determining the dissolved water content of biodiesel.
6.27 Free Water and Sediment Content This parameter measures the amount of free water and solid debris in the fuel. Free water is generally minimised by ‘housekeeping’ issues, such as draining water from storage tanks, ensuring no rainwater can enter through seals or valves and by not drawing from the bottom of the tank.35 Sediment can be entrained in the water or collect from dust or the precipitation of fuel components. Vehicle emissions and engine operability Separated water in biodiesel can reduce storage ability or lead to the separation of water when blending with diesel. Water can cause corrosion of engine fuel system components. This may take the form of rust, or acid corrosion where water becomes acidic over time. The presence of water in fuel may also encourage microbial growth, which grow in the interface between fuel and free water usually collected in the bottom of the storage tank. Sludges and slimes produced by these organisms can cause filter plugging. In some cases, the microbes may convert any sulfur present to sulfuric acid which corrodes storage tanks.35 Water increases the electrical conductivity of fuel.54 Sediment causes deposits on engine parts and consequently reduces engine life. International trends The European prEN 14214 biodiesel standard sets a limit for water content of < 500 mg/kg. The US ASTM D 6751 biodiesel standard sets a limit for water and sediment of 0.050 max % volume (< 500mg/kg). Test methods The European prEN 14214 standard specifies EN ISO 12937 test method for determining water content.
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ASTM D 6751 prescribes test method ASTM D 2709 as the referee method for determining water and sediment content. ASTM D 1796 may also be used. The precision and bias of these test methods with biodiesel is not known and is currently under investigation.11 ASTM D 2709 is also used for testing diesel.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for water and sediment content in biodiesel; and (b) an appropriate test method for determining water and sediment content in biodiesel.
6.28 Corrosion Some sulfur compounds in fuel are actively corrosive and are known as active sulfur. Acids (such as fatty acids) present can also cause corrosion. These are measured as a rate of copper strip corrosion, which indicates what storage and handling problems may arise. This parameter is an indication of the possible corrosion difficulties with copper, brass or bronze. Vehicle emissions and engine operability Corrosion can affect all materials in contact with the fuel, particularly engine components and storage and handling equipment. As acids are also included in this parameter, it is related to the acid value (or neutralisation number – See Section 6.9 Acid Value). This affects engine operability and lubricant oil properties. International trends The European prEN 14214 biodiesel standard sets a limit for copper strip corrosion of No.1 (3h at 50oC). The US ASTM D 6751 biodiesel standard sets a limit for copper strip corrosion of No.3 max (3h at 50oC). Test methods The European prEN 14214 standard specifies EN ISO 2160 test method for determining copper strip corrosion. ASTM D 6751 prescribes test method ASTM D 130 for determining copper strip corrosion. This test serves as a measure of possible difficulties with copper and brass or bronze parts of the fuel system. The presence of acids or sulfur-containing compounds can tarnish the copper strip, thus indicating the possibility for corrosion.
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According to Howell13 no biodiesel samples have been reported as measuring less than class 1 in the field so far in the US. Copper strip corrosion is tested in the same manner for both diesel and biodiesel.
Stakeholders are specifically requested to provide comment on: (a) an appropriate Australian specification for copper strip corrosion in biodiesel; and (b) an appropriate test method for determining copper strip corrosion in biodiesel.
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7 ALCOHOL
7.1 Methanol and Ethanol as reagents Any primary or secondary monohydric aliphatic alcohol having 1-8 carbon atoms can be used in transesterification. More commonly used alcohols are methanol and ethanol and some testing has been performed on butanol. Currently, methanol is the most researched reagent due to its low cost and physical and chemical advantages. However, environmental concerns are driving researchers to consider ethanol, as it is generally more environmentally benign than methanol. Further, in Australia ethanol from renewable sources is more readily available than renewable methanol. In Australia methanol is not an excisable product whereas ethanol is excisable and hence access to commercial quantities of ethanol for biodiesel production is subject to the controls of the excise legislation. A recent US EPA emissions study stated that in relation to methyl esters versus ethyl esters, it would be valuable to have information on how different transesterification processes on the same batch of plant or animal oil may lead to biodiesel exhibiting different emissions impacts.14
7.2 Alcohol properties Ethanol is generally recognised as being more environmentally compatible and a safer processing material than methanol. Ethanol is the most widely used renewable fuel in the world and is commonly derived from crops (sugar cane, sugar beet, wheat or cellulose sources). Methanol can be derived from natural gas, coal, crude oil and biomass crops. At present, however, natural gas is by far the most economically and environmentally viable source although methanol would need to be produced from biomass to make a contribution towards reducing greenhouse gas emissions. Current research indicates that the production of methanol from biomass may be more efficient than ethanol production.59 Methanol is highly toxic, can be absorbed through the skin, and is 100% miscible with water, therefore spills present a serious problem to aquatic life.36 The lower flash point of methanol presents safety issues. Although alcohol can also potentially affect fuel pumps, seals and elastomers, as long as the biodiesel meets specified standards eg, prEN 14214 for methanol content, this should not be a problem.
7.3 Differences between production technologies The general process of transesterification is very similar for both methanol and ethanol use. Until the alcohol is separated for recirculation, the processing units required are the same. One important difference is the amount of each alcohol required for effective transesterification. The methyl ester process utilizes 100% molar excess alcohol,
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whilst the ethyl ester process utilizes 70% stoichiometric excess ethanol (both 100% pure).36 In terms of volume, more ethanol is required per litre of oil than methanol. The difference between ethanol and methanol are marked when separating alcohol from ester and glycerol for recirculation in the process. Whilst methanol recovery is a relatively simple process, the recovery of ethanol is complicated by its formation of an azeotrope with water. For the purpose of recycling, it is important to limit the amount of water in the recovered ethanol stream. However ethanol can only be distilled to 95% purity with conventional methods. Despite these differences, final biodiesel samples (when processed correctly) have been found in comparative testing to contain less than one percent alcohol for both cases.58 Residual alcohol affects the flash point of the final product, and high concentrations (>5%) of methanol could impact on fuel lubricity and the cetane number.35 Ethanol has a higher flash point than methanol so the allowable limit of ethanol in biodiesel is higher.
7.4 Reaction conversion During biodiesel production conversion rates with ethanol can be lower e.g. 94.3% as opposed to 97.5% for methanol.36 This may be due to the more aggressive nature the of smaller methanol molecules in chemical reactions. An incomplete conversion indicates that mono-, and di-glycerides remain in the final product (See Section 6.12 – Mono- and Diglycerides). These are generally limited in biodiesel standards as they can cause carbon deposits on the fuel injector tips and piston rings.35 Further, crystallization of the saturated mono-glycerides in particular may occur due to their low solubility in methyl esters unless high temperatures are maintained. Conversely, cloud point (See Section 6.20 – Cloud Point) is increased with increasing saturated mono- and di-glycerides present.
7.5 Glycerol Content The total glycerol content of the final biodiesel product can also differ, with testing by the University of Idaho finding ethyl esters containing 1.4% glycerol compared with 0.87% in methyl esters.36 Free glycerin (See Section – 6.14 Free Glycerol), is associated with deposit formation in the engine. Its tendency to accumulate at the bottom of fuel tanks also leads to the concentration of water and monoglycerides in that area, due to their affinity for glyceride. Adequate washing in the processing stage should minimise this problem.35
7.6 Viscosity Biodiesel is generally approximately twice as viscous as diesel fuel. Neat vegetable oil is almost 12 times as viscous as diesel fuel.58 Ethyl esters tend to be considerably more viscous than methyl esters (up to seven times more viscous) and can inhibit fuel flow. This can lead to altered injector spray patterns, excessive coking and oil dilution.
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7.7 Impacts on vehicle emissions and engine operability One disadvantage of biodiesel is its reduced engine performance when compared with diesel. Peterson et al58 found that power was decreased by 4 percent for ethyl esters and 2.5 percent for methyl esters compared to diesel.58 Testing by the University of Idaho also found that methyl esters produce a slightly higher power output and torque than ethyl esters. However, fuel consumption were almost identical apart from brake specific fuel consumption when ethyl esters required 12% more and methyl esters 10% more than diesel.58 Overall observations on engine fouling in favour of ethyl esters are lower exhaust temperature, smoke opacity and fewer deposits in the combustion chamber. Further, NOx levels have been measured higher for methyl ester fuels.58 However, ethyl esters are associated with higher injector coking and higher glycerol content than methyl esters. Table 7.7 - summarises the differences between ethanol and methanol in biodiesel production. Table 7.7: Summary of Methanol and Ethanol effects
Property Methyl ester Ethyl ester Conversion 97.5% 94.3% Glycerol 0.87% 1.4% Viscosity 3.9-5.65 7.2% more than methyl ester Power output 2.5% lower than diesel 4% lower than diesel Brake fuel consumption 10% higher than diesel 12% higher than diesel
Stakeholders are requested to comment on the issue of alcohol feedstock for the production of biodiesel and impacts on vehicle emissions and engine operability. Specifically stakeholders are asked to comment on the need, if any, to specify the alcohol that is used to produce biodiesel (as in the EU standard).
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8 TECHNICAL ANALYSIS OF THE IMPACTS OF BLENDING BIODIESEL WITH DIESEL
8.1 Effect on Engine Operability Over time, biodiesel will soften and degrade certain types of elastomers and natural rubber compounds. This can have an impact on fuel system components (primarily fuel hoses and fuel pump seals) that contain these compounds. The recent move to low-sulphur diesel fuel has prompted many OEMs (original equipment manufacturers) to switch to fuel system components suitable for use with biodiesel. Lubrication is the most prominent benefit associated with the use of a 2% biodiesel blend - B2. Fuel consumption, power output or engine torque are not compromised for this lubricity, since B2 is nearly identical to diesel relative to these factors. Bohr et al60 performed a study on the effects of fuelling a light duty diesel compression ignition engine with biodiesel blends. The conclusions of the study indicate that:
Increasing concentrations of biodiesel blended with diesel cause a decrease in fuel economy;
Diesel and biodiesel mixtures were found to have no significant change in colour and no significant change in sediment;
Diesel and biodiesel blends were found to cause varying degrees of metal corrosion inside engines, however there is no pattern between increased biodiesel component of blended fuel and increased corrosion or vice versa; and
There is no significant difference between the drivability of vehicles fuelled with 100% diesel and vehicles fuelled with 80% diesel and 20% biodiesel at a temperature of –11°C. Fuel blends with greater proportions of biodiesel failed to operate at this temperature.
A discussion on the effect of blending diesel with biodiesel for some parameters is presented below.
8.1.1 Ester content Blending biodiesel with diesel will reduce the proportion of unreacted feedstock in the fuel. Therefore, engine operability factors should be improved, based on the decreased viscosity and associated benefits to engine operability. There is no limit for the ester content in diesel as diesel should have no esters in it, therefore the ester content of biodiesel blended fuels must be considered.
8.1.2 Kinematic Viscosity Blending biodiesel with diesel will reduce the kinematic viscosity of biodiesel portion. Therefore, engine operability factors should be improved when compared to B100. However, biodiesel blended with diesel that is close to the upper limit
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specified in the Fuel Standards (Automotive Diesel) Determination 2001 for kinematic viscosity for diesel, will result in a blended diesel fuel that does not comply with the Fuel Standard (Automotive Diesel) Determination 2001.
8.1.3 Cetane Number Blending biodiesel with diesel will improve the cetane number of the blend and decrease the cetane number when compared to B100 fuel. The Fuel Standards (Automotive Diesel) Determination 2001 specifies the cetane index for diesel. Cetane Number/Index The cetane index is not an appropriate measure for the cetane number of biodiesel fuels (Refer to Section 6.6).
8.1.4 Sulphated Ash Content The Fuel Standards (Automotive Diesel) Determination 2001 limits the ash and suspended solid content to less than 100 mg/kg. It is believed that the specification for the ash content of diesel fuel could be met for biodiesel through the employment of approximately 1 or 2 washes. Therefore the ash content specified in the Fuel Standards (Automotive Diesel) Determination 2001 should be achievable for any type of blended biodiesel with diesel. Therefore, the effects on engine operability from the ash content should be controlled.
8.1.5 Total Contaminants The Fuel Standards (Automotive Diesel) Determination 2001 does not have a limit for total contaminants. Biodiesel standards internationally have limits for total impurities in biodiesel. The use of alkaline catalysts during biodiesel production yields lower total contaminants in biodiesel. Employing alkaline catalysts and water washing technique, should ensure that all biodiesel contamination levels are met. Assuming the diesel meets relevant standards, blending biodiesel with diesel should yield lower total contamination when compared to B100.
8.1.6 Acid Value The Fuel Standards (Automotive Diesel) Determination 2001 does not currently specify a limit for TAN as diesel does not contain acids. TAN will be specified when the maximum sulphur content of diesel is mandated at 50 ppm in 2006. Acid values above 0.10 mg KOH/g have been shown to cause deposits on fuel systems causing a reduced pump and filter life.25 Furthermore, biodiesel will increase the acidity of the lubricating engine oil once significant amounts enter the engine crankcase.41 Tighter seals on modern diesel engines surrounding the engine crankcase should reduce the potential for the engine oil to become contaminated. The acid number is also associated with corrosion of engine parts.42 The ASTM D 6751 specified acid number for a 20% biodiesel and 80% diesel blend, based on 1000 hour pump stand durability testing, is 0.80 mg KOH/g.
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8.1.7 Iodine Number A high level of unsaturation in the biodiesel will cause polymerisation of the lubricating engine oil if the biodiesel infiltrates the engine crankcase. Heating biodiesel increases the rate of the polymerisation reaction and reduces the induction period (i.e. time it takes for the polymerisation reaction to begin). Polymerisation of biodiesel increases the fuel viscosity, adversely affecting the fuel’s ease of flow, causing the formation of engine deposits and adversely affecting fuel injector spray patterns. This will ultimately lead to engine failure. Diesel contains approximately 98% aromatics and 2% alkanes.61 Polymerisation does not occur to either aromatics or alkanes. Blending biodiesel with diesel will reduce the proportion of fuel that contains aliphatic unsaturated bonds, thereby reducing the iodine number of the fuel. The effect of polymerisation of biodiesel and lubricating engine oil on engine operability will therefore be reduced. The Fuel Standards (Automotive Diesel) Determination 2001 does not specify a limit for iodine number.
8.1.8 Linoleic Acid Methyl Ester Blending biodiesel with diesel will reduce the proportion of linoleic acid in the fuel thereby decreasing the rate of polymerisation and potential impacts in engine operability.
8.1.9 Mono- and Diglyceride Content Mono- and diglyceride content in biodiesel are associated with carbon deposits on fuel injector tips and piston rings, thus adversely affecting fuel flow. Monoglycerides have relatively high melting points and have a low solubility in methyl esters that cause crystallisation in the fuel. Diesel does not contain mono or diglycerides. The effect of blending biodiesel with diesel will reduce the content of mono and diglycerides in the fuel. This should minimise the adverse impacts caused by the mono and diglycerides on engine operability.
8.1.10 Triglyceride Content Triglycerides have a high viscosity as compared with diesel. Blending biodiesel with diesel will reduce the content of triglycerides in the fuel. The relatively low viscosity of diesel and the fact that diesel will not undergo polymerisation, indicates that the adverse engine operability effect caused by a high triglyceride content of the fuel will be minimised through fuel blending.
8.1.11 Free glycerin Blending diesel with biodiesel lowers free glycerol content.
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8.1.12 Alkaline Metals The Fuel Standards (Automotive Diesel) Determination 2001 specifies a limit of 100 mg/kg for suspended ash and solids in diesel fuel. This limit should be appropriate for all blends of biodiesel and diesel, as the effect of ash and suspended solids is the same on engine operability (i.e. blocked fuel lines and fuel injector nozzles).
8.2 Impacts on emissions Section 4 discussed issues relating to impacts of biodiesel use, including emissions of neat biodiesel and biodiesel blends. Generally, most emissions observed from the combustion of diesel in internal combustion engines are reduced when using biodiesel as the engine fuel. Biodiesel has been reported to be more sensitive to changes in engine parameters than diesel.33
Stakeholders are requested to comment on the impacts of blending biodiesel with diesel on engine operability and vehicle emissions. Section 10 – Vehicle Warranties and Labelling should be referred to when commenting on this section.
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9 EFFECT OF BIODIESEL ON DIESEL ENGINE OIL Research suggests that various esters of vegetable oil may cause the engine lubricating oil in vehicles to thicken, to become more acidic and/or diluted.42 Thickening of engine oil is due to oil polymerisation. Polymerisation of oils occurs through the interaction of double bonds and oxygen to form peroxides. In neat vegetable oils polymerisation occurs naturally. Esters of vegetable oils will have different rates of polymerisation, however polymerisation still occurs.
9.1 Polymerisation of Vegetable Oil Derived Esters This section describes the chemistry of ester polymerisation to assist the understanding of the effects biodiesel has on diesel engine oil.
9.1.1 Initiation Phase (Induction Period) The initiation of the oxidative chain reaction responsible for the drying of natural oils is preceded by an induction period. This has been attributed to the presence of natural antioxidants such as tocopherol.42 The induction period is defined as the period of time necessary for the initiation of oxygen adsorption. The oxygen adsorption is perceived to cause the oxidation chain reaction through oxygen attaching to the double bond of unsaturated esters thereby producing the polymerisation reaction. Temperatures above 55°C reduce the length of the induction period substantially42 and there is a positive correlation between temperature and polymerisation rate.62 Du Plessis et al63 showed that methyl esters had higher concentrations of tocopherols than ethyl esters. Therefore, methyl esters have longer induction periods than ethyl esters and are more stable.
9.1.2 Metal Catalysts Metal elements have been shown to have an accelerating effect on the polymerisation of unsaturated fatty esters.64,65 Table.9.1.2 lists the identified metals and their effect on the rate of polymerisation. Table 9.1.2: Metal effects on polymerisation
Metal Effect on Polymerisation/Reactivity Cobalt Increase greatly/very high reactivity Lead Increase greatly/very high reactivity
Manganese Increase greatly/very high reactivity Copper Increase greatly/very high reactivity
Iron Increase greatly/very high reactivity Chromium Increase/high reactivity
Cesium Increase/high reactivity Tin Increase/high reactivity
Vanadium Increase/high reactivity Zirconium Increase/high reactivity
Calcium/Zinc/Lead Combination Increase/high reactivity
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9.1.3 Lipoxidase – Naturally Occurring Enzyme Lipoxidase is found in various plant oils (such as soybeans) and is a powerful and specific oxidation catalyst for unsaturated fatty acids containing methylene interrupted multiple bond systems that are in the cis configuration.64 All double bonds of polyunsaturated (> 2 double bonds) fatty acids are in the cis configuration. Lipoxidase increases the rate of oxidation as the activation energy of the lipoxidase reaction is much lower than other possible oxidation reactions, thereby increasing the rate of oxidation.42
9.1.4 Thermal Polymerisation This type of oxidation occurs when the ester is heated to a temperature of approximately 150°C with the absence of oxygen.64 The degree of unsaturation decreases while the density and viscosity increase.
9.1.5 “Rise and Fall” Viscosity Pattern As vegetable oil begins to polymerise, a rise in viscosity is observed which is followed by a reduction in viscosity, which eventually reverts to a rise in viscosity.42 Ultimately, viscosity increases until the gel point is reached.
9.1.6 Antioxidant additives There are several food grade antioxidants that can be added to biodiesel to reduce the polymerisation significantly. Although food grade antioxidants are often heat sensitive and volatile, experiments with methanolic extract of Noble oat in soybean and cottonseed oil at 180°C have shown that this food grade antioxidant reduces oil polymerisation significantly.42 Antioxidants reduce polymerisation by increasing the oxidation induction period in the same manner as the naturally occurring antioxidant, tocopherol. Food grade antioxidants include butylated hydroxyanisole (BHA), butylated hydroxy toluene (BHT) and tertiary butyl hydroquinone (TBHQ), which are effective antioxidants at room temperatures.
9.2 Potential Oil Degradation Factors The following is a summary of the potential oil degradation factors. Further information is at Appendix E. The chemical potential for biodiesel that has infiltrated the engine crankcase to polymerise (thicken) the engine lubricating oil exists. The polymerisation reaction occurs more rapidly in engine oils with high concentrations of linoleic and linolenic acids and a high level of unsaturated bonds (i.e. high iodine value). Although the iodine number of biodiesel fuel has been shown to have a positive correlation with engine oil polymerisation, biodiesel with iodine numbers of between 100 and 140 do not show significantly different rates of engine oil polymerisation. The United States National Biodiesel Board recommends that operators of biodiesel fuelled equipment use engine lubricating oils with high dispersancy additives, as these oil types should reduce the potential for engine oil polymerisation.
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Synthetic oils should be more resistant to engine oil polymerisation and more work needs to be completed to ascertain the extent of polymerisation control achievable through the use of synthetic oils. The engine oil acid number is not affected until after the engine oil viscosity limits are exceeded.42 Standard procedures used to evaluate engine oil polymerisation consist of determining the percent fuel dilution in the engine lubricating oil. Fuel dilution meters involve heating a sample of used engine oil and detecting the amount of fuel vapour. Due to the high boiling point of biodiesel (between 320 – 350°C) most fuel dilution meters will not detect fuel vapours of biodiesel. Therefore, viscosity is judged to be the most accurate indicator of engine oil polymerisation.42 Direct injection diesel engines show a higher incidence of fuel infiltrating the crankcase and into the engine lubricating oil than indirect injection diesel engines.42 Modern direct injection and indirect injection diesel engines are designed with tighter rings and cylinders surrounding the engine crankcase.42
Stakeholders are requested to comment on the impacts of biodiesel on diesel engine oil. Section 8 – Technical Analysis of the Impacts of Blending Biodiesel with Diesel on blending and 10 – Vehicle Warranties and Labelling should be referred to when commenting on this section.
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10 VEHICLE WARRANTIES AND LABELLING
10.1 Warranties Engine manufacturers warranty their engines for “materials and workmanship”. An engine company will cover the rectification of a fault with an engine part or with engine operation within the prescribed warranty period, if the fault is due to an error in manufacturing or assembly. Typically, an engine company will define what fuel the engine was designed for and will recommend the use of that fuel to their customers in their owner's manuals. Engine companies do not warranty fuel, whether petrol, diesel or biodiesel. Engine problems arising directly from fuel use (and not a fault in materials and workmanship) are the responsibility of the fuel supplier and not the engine manufacturer. Therefore, the most important aspect regarding engine warranties and biodiesel is whether an engine manufacturer will void its parts and workmanship warranty when biodiesel is used, and whether the fuel producer or marketer will stand behind its fuels should problems occur.
10.2 The International Experience Europe The first European warranties for biodiesel use issued were given for tractors or combines only. For example, Case–IH tractors have been approved to operate on biodiesel since 1971. Other manufacturers of agricultural equipment that have historically upheld warranties with the use of biodiesel are Fiatagri, Ford AG, Holder, Kubota, Massey-Ferguson, and Mercedes-Benz Tractors since 1989.66 Volkswagen AG, including the brands Audi, Seat, Skoda and Volkswagen from 1996 onwards, have supported the use of biodiesel in European countries. The German DIN 51606 standard for Fatty-acid-methyl-ester (FAME) was published in 1997, and this strengthened the quality control requirements of engine and equipment manufacturers allowing further companies to issue biodiesel engine warranties for the use of B100 fuels.66
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A current list of European manufacturers issuing warranties for biodiesel is below (adapted from Austrian Biofuels Institute66): Table 10.1: Current European Biodiesel Warranties
Manufacturer Vehicle class Description
Audi personal cars all TDI-models since 1996 Case - IH tractors all models since 1971 BMW personal car model 525 tds / 1997 and 3er + 5er since 2001 Claas combines, tractors warranties exist Faryman Diesel engines warranties exist Fiatagri tractors for new models Ford AG tractors for new models Holder tractors warranties exist Iseki tractors series 3000 and 5000 John Deere tractors warranties since 1987 John Deere combines warranties since 1987 KHD tractors warranties exist Kubota tractors series OC, Super Mini, O5, O3, Lamborghini tractors series 1000 Mercedes-Benz personal cars series C and E 220, C 200 and 220 CDI, a.o. Mercedes-Benz lorry, bus series BR 300, 400, Unimog since 1988, a.o. Nissan personal car type Primera since 2001 Same tractors since 1990 Seat personal cars all TDI-series since 1996 Skoda personal cars all TDI-series since 1996 Steyr tractors since 1988 Steyr boat series M 16 TCAM and M 14 TCAM Valmet tractors since 1991 Volkswagen personal cars all TDI- series since 1996 Volkswagen personal cars all new SDI-series (EURO-3) Volvo personal cars series S80-D, S70-TDI and V70-TDI
US
The United States situation is slightly different to that existing in Europe, as approximately 99% of all biodiesel is used in blends of B20 or less.13 Most manufacturers have formally stated that use of biodiesel up to B20 blend will not void their materials and workmanship warranties67, providing that the biodiesel is manufactured to meet ASTM D 6751 quality standard.
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World-Wide Fuel Charter
The draft third edition of the World-Wide Fuel Charter (WWFC) contains the following information regarding FAME.68
Fatty Acid Methyl Esters (FAME) including vegetable derived esters (VDE) are increasingly being used as extenders to, or replacements of, diesel fuel. This has been driven largely by national efforts to exploit agricultural produce and/or to reduce the dependency on imported oil products. Some data suggests that environmental benefits can be achieved through the use of these esters. However, manufacturers do have concerns over the introduction of vegetable derived esters in high quality diesel fuel.
Many oils may be used for making methyl esters, eg., rapeseed, sunflower, palm, soya, cooking oils and animal fats, but to date, the rapeseed product comes closest to the behaviour of conventional diesel fuel. For example, typical characteristics for rapeseed methyl ester (RME) are as follows:
cetane number = 51 density = 0.880 kg/m3 viscosity at 40°C = 3.5 mm2/sec
• The technical advantages of methyl ester are primarily that they ensure
lubricity of injection equipment (lubricity can be diminished by the refining processes to remove diesel sulfur) and they reduce exhaust gas particulate matter. The disadvantages of methyl esters are as follows:
• They require special care at low temperatures to avoid excessive rise in viscosity and loss of fluidity. Additives may be required to alleviate the problems.
• Being hygroscopic, special care is needed to prevent high water content and the consequent risk of corrosion.
• Deposit formations tend to be higher than for diesel fuel, so detergent additive treatment is strongly advisable.
• Seals and composite materials in the fuel system are attacked by methyl esters unless they are specially chosen for their compatibility.
Based on the technical effects of FAME, it is strongly advised that FAME content be restricted to less than or at 5%. As a pure fuel, or at higher levels in diesel fuel, the vehicles need to be adapted to the fuel, and particular care is needed to avoid problems.
The European standards organisation CEN is finishing in 2002 the FAME specification prEN 14214 to be used as diesel fuel in engines designed or adapted for this fuel. The group is also evaluating the diesel fuel specifications to determine if changes are needed to either the parameters or
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test methods to accommodate the introduction of FAME as a diesel extender at levels up to 5%. Until this work is completed and based on the technical concerns raised by the introduction of FAME in diesel fuel, it should not be introduced into a high quality fuel such as required in Category 4 markets. ASTM recently approved a standard specification (D 6751) for biodiesel (B100) that is still under review by some automakers and engine manufacturers. Non-extended fatty acids are not acceptable for use as fuels.
Engine Manufacturers Association.
In the United States, Engine Manufacturers Association (EMA) is a representative for the engine manufacturing industry on domestic and international public policy, regulatory, and technical issues that impact manufacturers of engines used in a broad array of mobile and stationary applications. EMA states that engine manufacturers must warrant their products’ emissions performance, and they generally warrant their materials and workmanship. In their draft technical statement they advise that individual engine manufacturers will determine on their own what implications, if any, the use of biodiesel fuel has on the manufacturers’ commercial warranty. Due to the range in composition of biodiesel products, biodiesel fuel and fuel system suppliers should warrant against any damage arising from their products’ failure to meet the specifications and quality they have described. In addition, inasmuch as the long-term effects of pure biodiesel and biodiesel blends on engine performance, durability and emissions compliance are uncertain, biodiesel fuel and fuel system suppliers also should bear responsibility for any damage to the engine or fuel system caused by the use of their product.69
The use of biodiesel or biodiesel blends in and of itself will not void fuel injection equipment (FIE) warranties. Some FIE manufacturers have special equipment designed for high blends of biodiesel, including B100. The FIE manufacturers should always be consulted regarding the limits of their products.11 Fuel Injection Equipment (FIE) manufacturers (Bosch, Delphi, Stanadyne, Denso)
A joint Fuel Injection Equipment (FIE) Manufacturers Statement was issued in June 2000 in relation to the use of FAME fuels as a replacement or extender for diesel fuels. The FIE manufacturers can accept no legal liability for failure attributable to operating their products with fuels for which the products were not designed, and no warranties or representations are made as to the possible effects of running these products with such fuels. Non-compliance of the fuel to standards agreed by the FIE manufacturers, whether being evident by appearance of the known degradation products of these fuels, or their known effects within the fuel injection equipment, will render the FIE Manufacturers guarantee null and void.54 A list of FIE potential problems is attached to the position statement and includes free methanol, free water, free glycerine and free fatty acids. Typically, a manufacturer will define the recommended fuel for the engine, although they will not cover fuel related problems with any fuel. In the US most major engine companies have formally stated that the use of a B20 blend or lower will not void their warranties. When used in concentrations higher than 20%, biodiesel can soften and degrade certain types of elastomers and natural rubber compounds over time. While the move to 500ppm sulfur diesel in 1993 caused many OEMs to switch
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components already suitable for use with higher levels of biodiesel, up to B100, fleet managers should contact their OEM for specific information.28 Stanadyne Automotive, the leading independent US manufacturer of diesel fuel injection equipment, have publicly supported the inclusion of 2% biodiesel into diesel to address lubricity concerns.22
10.3 The Australian Situation Australian vehicle manufacturers, vehicle distributors and parts manufacturers were consulted during the development of this discussion paper. The position of vehicle manufacturers, vehicle distributors, parts manufacturers and industry bodies in Australia is generally supportive of B5 blends but not of higher blends. Most manufacturers, including FIE (Fuel Injection Equipment) manufacturers, agree that a blend of up to and including B5 will not cause any significant effect on operability and not void warranties. Position statements on warranty status is briefly summarised in Table. 10.2.
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Table 10.2: Biodiesel position of engine and equipment manufacturers - Australia
Manufacturer Summarised position Cummins Engine Co. “Cummins neither approves or disapproves of the use of biodiesel fuel”.
Would recommend against B100. Up to B5 should not cause serious problems
Isuzu GM Australia Ltd. “Isuzu Japan neither approves nor prohibits using biodiesel fuel. Isuzu Japan recommend using the fuel that meet CEN prEN 14214 or ASTM D 6751 standard”
B5 may be acceptable providing the biodiesel meets one of the acceptable standards. No formal approval is given to customers.
Mitsubishi Motors Australia.
Voids warranty. Have no data of testing on B100 or blends.
Premier Automotive Group (Aston Martin, Jaguar, Land Rover and Volvo Car).
B5 only
Scania Australia. B5 only
Volvo Truck. B4 only
Caterpillar Neither approves nor prohibits the use of biodiesel fuels. Failures resulting from the use of any fuel are not Caterpillar factory defects and therefore the cost of repair would NOT be covered by Caterpillar’s warranty.
When using a fuel that meets Caterpillar’s Biodiesel specifications, ASTM PS121 or DIN 51606 and following recommendations, the use should pose no problems.
Daimler Chrysler AustraliaPacific Commercial vehicles
Fuel must meet DIN 51606 and STIN 00.00S028. Use of B100 would not necessarily void warranties. Up to B5 suitable for all engines.
UD Nissan Trucks. Have not discussed with international headquarters, but state that “The use of biodiesel would make the vehicle's warranty conditional.” Relevant testing would be required.
Mazda Australia Pty Ltd. Voids warranty.
Holden. B5 (as methyl ester).
Toyota Australia Engineering responsibility for all Toyota diesel engines rests in parent company – Toyota Motor Corporation Japan. Questionnaire referred to them.
Volkswagen Group Australia
Warranties would not be voided if the engine is released for use with RME (rapeseed methyl ester) biodiesel and the biodiesel met the European norm standard pr EN 14214.
Stakeholders are requested to comment on the issue of biodiesel warranties for use in vehicles in Australia. Specifically stakeholders are asked to comment on any experience with negotiating warranties for biodiesel use.
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10.4 Australian Design Rule (ADR) Compliance CSIRO1 report that 100% biodiesel can be expected to meet all future Australian Design Rules for all pollutants except oxides of nitrogen which may be slightly above Euro3 and Euro4 standards, and possibly the particulate matter standard for Euro3 (and therefore Euro 4). There is limited data for 100% biodiesel on which to make this judgement and none of the data from the CSIRO report was derived from current Euro 3 or latest US technology vehicles. A blend of 20%-30% biodiesel with diesel in heavy vehicles is expected to meet all Euro4 standards.
10.5 Other compliance The assessment of the suitability of associated equipment in the processing, storage, distribution and delivery of biodiesel was not an objective of this discussion paper. Stakeholders are requested to comment on issues relating to the suitability of current infrastructure, or any requirements for specialised infrastructure, for the use of biodiesel.
10.6 Labelling There may be a case for labelling the biodiesel content of fuel at the bowser due to a number of characteristics that differ from those of diesel. Examples of information that might be relevant to the end-user includes:
• The proportion of biodiesel in the blend; • Warranty information and suitability for certain engines; • Fuel consumption; • Density; • Sulfur levels/lubricity; and • Cold flow properties.
At present the Fuel Quality Standards Act 2000 does not contain labelling provisions. Stakeholders are invited to comment on the case for labelling of biodiesel/biodiesel blends and what information would be relevant to the end-user.
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55. Dunn R and Bagby M. Low-Temperature Filterability Properties of Alternative Diesel Fuels from Vegetable Oils 1996. Available at http://www.biodiesel.org/resources/reportsdatabase/reports/gen/gen-150.pdf, last accessed September 2002. 56. Fats and Proteins Research Foundation. Technical Services Bulletin, July 2001 (2 of 3), Available at www.fprf.org/profile/tech_bulletins/tsb_701_b.htm, last accessed September 2002. 57. Zheng D and Hanna M. Preparation and Properties of Methyl Esters of Beef Tallow. Department of Biological Systems Engineering, University of Nebraska-Lincoln, USA, 1995. Available at http://www.biodiesel.org/resources/reportsdatabase/reports/gen/gen-224.pdf, Last accessed September 2002. 58. Peterson CL, Hammond B, Thompson J, Beck S. Performance and Durability Testing of Diesel Engines Using Ethyl and Methyl Ester Fuels, Department of Biological and Agricultural Engineering for the National Biodiesel Board, University of Idaho, Moscow, Idaho 83844-2060 Submitted in completion of contract #52016-l 1995. Accessible at www.biodiesel.org/resources/reportsdatabase/reports/gen/gen-158.pdf, last accessed September 2002. 59. Foran B. Developing a Biofuel Economy in Australia by 2025, CSIRO Resource Futures. 2001. Accessible at: http://www.dwe.csiro.au/research/futures/publications/01-10.pdf. last accessed Septemeber 2002. 60. Bohr B, Horejsi M, Johnson J, Kovacs T, Masuduzzaman M, Jones B, et al. Bioblended Fuel for use in Light Duty Compression Ignition Engines. Presented to The Great Lakes Regional Biomass Energy Program by Mankato State University, Automotive Engineering Technology, May 23, 1997, U.S.A. 61. BP. Pers. Comm.. BP, Bulwer Refinery 2001. 62. Erhan SZ and Bagby MO. Polymerization of vegetable oils and their uses in printing inks. J of the American Oil Chemists Society, 1994;71(11):1223-1226. 63. Du Plessis LM, DeVilliers JBM, Van Der Walt WH. Stability studies on methyl and ethyl fatty acid esters of sunflower seed oil. J of the American Oil Chemists Society, 1985;62(4):748-752. 64. Wexler H. Polymerization of drying oils. Chemical Reviews, 1964;64(6):591-611. 65. Sedlacek BA. Studium der UV-Sepktren erhitzter Fette. 14. Mitt. Vergleich des Eiusses einiger Schwermetaltkationen auf die thermishe Oxydation und Polymerisation von Sonnenblumenoet, Die Nahmng, 1973;17(6).
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66. Austrian Biofuels Institute (ABI). Biodiesel – a Success Story – The Development of Biodiesel in Germany. IEA Task 27, Austrian Biofuels Institute, 2002. 67. Lang K. Biodiesel, On the Road to fuelling the future. National Biodiesel Board in association with Hart – Diesel Fuel News – Harts World Refining. 2001. 68. World-Wide Fuel Charter – Draft for Comments – June 2002. 69. Engine Manufacturers Association. Technical Statement on the Use of Biodiesel Fuel in Compression Ignition Engines. Draft April, 2002. 70. Bockey D. Biodiesel Production and Marketing in Germany, UFOP. 2002. Available at: www.biodiesel.org/resources/reportsdatabase/reports/gen/071002_biod_in_germany.pdf, last accessed September 2002. 71. Körbitz W and Prankl H. Non-Technical barriers for liquid biofuels – Network Phase IV, Status report for Europe. 2000. 72. ENER – IURE Project Phase III – Report concerning agriculture in Portugal, 27 June 2002. 73. Schuchardt U, Sercheli R, Vargas RM. Transesterification of Vegetable Oils (a Review), J Braz. Chem. Soc., 1998;9(1):199–210. 74. National Biodiesel Board (USA), Biodiesel Production and Quality. 2002. Available at www.biodiesel.org/pdf_files/prod_quality.pdf last accessed September 2002. 75. Körbitz W. Biodiesel Questionnaire Reply. Pacific Air & Environment Pty Ltd, Australia, 2002(a). 77. Mittelbach M, Pokits B and Silberholz A. Diesel fuel derived from vegetable oils, IV: production and fuel properties of fatty acid methyl esters from used frying oil. Liquid Fuels from Renewable Sources, Proceedings of Alternative Energy Conference, 14 – 15 December 1992. American Society of Agricultural Engineers, Michigan, USA, 1992:74. 78. Rice B, Frohlich R, Leonard R, Korbitz W. (1997). Biodiesel Production based on Waste Cooking Oil: Promotion of the Establishment of an Industry in Ireland, Agriculture and Food Development Authority, Final Report, September 1997. 79. Staat F and Gateau P. The effects of rapeseed oil methyl ester on diesel engine performance, exhaust emissions and tong-term behavior - A summary of three years of experimentation. SAE Paper No. 950053. 1995. 80. Bardasz EA, Cowling SV, Ebeling VL, George HF, Graf MM, Kornbrekke RE, et al. Understanding soot mediated oil thickening through designed experimentation, Part 1: Mack EMG-287, GM 6.2L. SAE Paper No. 952527. 1995.
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APPENDIX A – FUEL QUALITY STANDARDS FOR PETROL AND DIESEL
Table.1 Petrol Standards Parameter Standard Grade Date of effect
Sulfur 500 ppm (max) 150 ppm (max) 150 ppm (max)
ULP/LRP PULP All grades
1 Jan 2002 1 Jan 2005
Research octane number (RON)
91 RON (min) 95 RON (min) 96 RON (min)
ULP PULP LRP
1 Jan 2002
Distillation FBP 210°C (max) All grades 1 Jan 2005
Olefins
18% pool average over 6 months with a cap of 20% 18% max by vol
All grades
1 Jan 2004 1 Jan 2005
Aromatics
45% pool average over 6 months with a cap of 48% 42% pool average over 6 months with a cap of 45%
All grades
1 Jan 2002 1 Jan 2005
Benzene 1% max by vol All grades 1 Jan 2006 Lead 0.005g/L (max) All grades 1 Jan 2002
Oxygen content 2.7% m/m (max)
All grades (other than petrol containing ethanol)
1 Jan 2002
Phosphorus 0.0013g/L (max) ULP, PULP 1 Jan 2002 MTBE (Methyl tertiary butyl ether)
1% by volume (max) All grades 1 Jan 2004
DIPE (Di-isopropropyl ether)
1% by volume (max) All grades 1 Jan 2002
TBA (Tertiary butyl alcohol)
0.5% by volume (max) All grades 1 Jan 2002
MON 85.0 (min) 81.0 (min) 82.0 (min)
PULP ULP LRP
16 Oct 2002 16 Oct 2002 16 Oct 2002
Copper Corrosion (3 hrs @ 500C) Class 1 (max) All 16 Oct 2002
Existent Gum (washed) 50 mg/L (max) All 16 Oct 2002
Induction Period 360 minutes (min) All 16 Oct 2002
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Table 2 Diesel Standards Parameter Standard Date of effect Sulfur 500 ppm
50 ppm 31 Dec 2002 1 Jan 2006
Cetane Index 46 (min) index
1 Jan 2002
Density 820 to 860 kg/m3 820 to 850 kg/m3
1 Jan 2002 1 Jan 2006
Distillation T95 370°C (max) 360°C (max)
1 Jan 2002 1 Jan 2006
Polyaromatic hydrocarbons (PAHs)
11% m/m (max)
1 Jan 2006
Ash and suspended solids 100 ppm (max) 1 Jan 2002 Viscosity 2.0 to 4.5 cSt @ 40°C 1 Jan 2002 Carbon Residue (10% distillation residue) 0.2 mass % max 16 Oct 2002
Water and sediment 0.05 vol % max 16 Oct 2002
Conductivity at ambient temp
50 per pS/m (Min) at ambient temp (only applies at terminals/refineries/major distribution centres)
16 Oct 2002
Oxidation Stability 25 mg/L max 16 Oct 2002 Colour 2 max 16 Oct 2002 Copper Corrosion (3 hrs @500C) Class 1 max 16 Oct 2002
Flash point 61.50C min 16 Oct 2002 Filter blocking tendency 2.0 max 16 Oct 2002 Lubricity 0.460 mm (max)
(only for diesel containing less than 500ppm sulfur)
16 Oct 2002
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APPENDIX B - INTERNATIONAL TRENDS IN BIODIESEL PRODUCTION AND USE
Europe The European biodiesel market is the world leader in terms of production and uptake. The market is characterised by the following descriptors:
Current biodiesel production capacity is over 2,000,000 tonnes. The European Union commission has set minimum target market share for
biological fuels (as opposed to mineral fuels) from 2% in 2005 to 5.75% in 2010. This includes biomass-derived fuels such as biodiesel and ethanol.
Raw material supply and production capabilities will ultimately limit biodiesel to approximately 10% of the diesel market.
The production capacities in individual European countries are o Germany 1,109,000 t/a (tonnes per annum) o France 440,000 t/a o Italy 350,000 t/a o Czech Republic 60,000 t/a o Denmark 60,000 t/a o Austria 45,000 t/a o Sweden 30,000 t/a
A number of factors have led to biodiesel being available in some European countries and not others. Key factors that have encouraged the uptake of biodiesel in some European countries are:
The widespread introduction of set-aside. European Community farmers are required to take a proportion of their land out of production (set-aside), in return for subsidies on their main crops. Crops intended for non-food uses (i.e., industrial or pharmaceutical) are allowed to be grown on set-aside land, but not crops for food use. One clear use of set-aside land is to produce non-food crops such as oilseed rape or sunflowers for biodiesel production.
A very strong agricultural lobby arguing for the development of biofuel (including biodiesel) industries.
Perceived or actual environmental benefits of biodiesel. Tax relief for pilot biofuel production plants under the European Community
“Scrivener” Directive. The Scrivener Directive provides a framework for tax relief for investment in liquid biofuel plants. According to one source, “Without this relief, the biofuel costs of production are between 2-3 times that of fossil fuels”.70 Lack of tax incentives makes direct competition between biodiesel and fossil diesel difficult.
A summary of the biodiesel market conditions that exist in several European countries is given in the following sections. Much of this work has been sourced from “Non-technical Barriers for Liquid Biofuels – network phase IV, Status Report for Europe 2000”71 and “Biodiesel – a Success Story, the Development of Biodiesel in Germany”, IEA Task 27, Austrian Biofuels Institute, 2002”66.
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Germany Germany has a biodiesel capacity of more than 1,000,000 tonnes, produced from approximately 15 industrial facilities. Biodiesel is approximately 3% of the total diesel market. The key points that have driven the success of the German biodiesel market66 are summarised below:
A high degree of co-ordination of common interests of farmers’ organisations and rapeseed (canola) breeders and seed producers, leading to the formation of the UFOP (Union for the Promotion of Oil and Protein Plants).
The Common Agricultural Policy of the European Union leading to 15% set-aside land. Biodiesel was recognised by farmers as the non-food product with the largest potential, encouraging the production of rapeseed (canola) oil.
A concerted drive to market B100 as an “individual and independent” fuel in order to obtain all environmental and image advantages. This contrasts with the French policy of almost exclusive B5 use. French biodiesel is therefore relatively anonymous, whereas biodiesel in Germany is generally known to the public and available from more than 1,500 public filling stations.
Positive and direct involvement from the beginning of the German car industry. Having won the confidence of the car industry allowed warranties for biodiesel use. The positive involvement of vehicle manufacturers is crucial in establishing a biodiesel market, as a market can only exist if vehicle warranties are upheld for biodiesel use. Setting of the mandatory German DIN V 51606 standard for PME (plant oil methyl ester) in 1994 gave sufficient confidence to vehicle manufacturers to assure the provisions of warranties for a large number of diesel passenger vehicles. Prior to this, only a few other companies had given warranties, mainly for agricultural equipment. To date, a large number of agricultural equipment manufacturers and an impressive list of vehicle passenger manufacturers have issued warranties. At the moment, there are approximately 2.5 million vehicles in Germany with biodiesel warranties.
The consistent and mandatory application of quality control using DIN 51606 standards as the basis for creating confidence with consumers and vehicle manufacturers.
Biodiesel is not taxed by the German government, while the tax on diesel is scheduled to increase to 2006. Therefore, biodiesel enjoys a price advantage over diesel at the bowser.
Secondary reasons for the success of the German biodiesel market include:
The growing attractiveness of the diesel engine due to recent performance improvements. Modern diesel engines are electronically controlled, sophisticated and offer high performance, high fuel economy and low exhaust levels. Modern diesel engines have more challenging requirements on both fossil diesel and biodiesel.
Pioneering work by motivated individuals in pilot plant construction.
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Persistent and targeted promotion strategy by the UFOP, involving conferences, seminars and scientifically validated and professionally presented information material.
Increase in the crude oil price from below $US 10 per barrel (Jan 1999) to more than $US 25 per barrel from December 1999 onwards
Whilst biodiesel production capacity in Germany has grown to over 1,000,000 t/a, 2002 sales are predicted to be approximately 550,000 tonnes. The development of biodiesel demand has not kept pace with the increase in production capacity, leading to price advantages for vehicle keepers in comparison to diesel. German biodiesel manufacturers are likely to also act as biodiesel exporters, given the European Union market rules for unrestricted trading. Interesting examples of successful marketing strategies are visible in the German market, particularly in the public transport sector. The local bus company of city of Hinsberg switched its entire fleet of 130 buses to biodiesel, after performing detailed economic comparisons between compressed natural gas (CNG) and biodiesel. The German Taxi Association have adopted biodiesel throughout Germany primarily due to its lower cost compared to fossil diesel, and its environmental benefits. This move also encouraged Mercedes-Benz, Volkswagen, Audi and Volvo to provide warranties for the use of biodiesel, as the German Taxi Association purchases their vehicles in bulk orders. Future scenarios for biodiesel in Germany, and in Europe more generally, are positive. The expansion of the European Union by an additional 10 Central and East European countries will add significant tracts of acreages. Food crop overproduction will continue to be regulated with the set-aside program, with demand for increasing the percentage of set-aside lands. Pressure will exist to develop non-food crops such as oilseed. Biodiesel can easily absorb large volumes of oilseeds. Biodiesel in Germany could well grow beyond the current case, because of the following key drivers:
A well prepared and existing national market; Entrenched and effective high product quality philosophy; Well developed diesel engine market, and Reasonably priced feedstock availability.
The key stakeholders in the German biodiesel market are the following. A much more detailed description for each stakeholder is given elsewhere (Austrian Biofuels Institute, 2002).
UFOP - Union for Promotion of Oilseed- and Protein plants (Union zur Förderung von Öl- und Proteinpflanzen).
DBV - German Farmers’ Association (Deutscher Bauernverband). BDP - German Plant Breeders’ Association (Bundesverband Deutscher
Pflanzenzüchter). VLK – Association of Chambers for Agriculture (Verband der
Landwirtschaftskammern). VDÖ - German Oilseed Crushing Association (Verband Deutscher Ölmühlen
e.V.).
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The biodiesel production industry, as represented by The Association of German Biodiesel Producers.
The diesel vehicle industry.
Austria Production capacity of approximately 45,000 tonnes. There are 6 commercial plants operational and one pilot plant. The biggest plant has capacity of approximately 22,000 tonnes per year. The major feedstock in use is rapeseed oil, therefore the leading market position is taken by Rapeseed Methyl Ester (RME). However, standards in Austria define biodiesel as the more general term ‘fatty-acid-methyl-esters’ (FAME) (Austrian ON C 1191 and German DIN E 51606). Approximately 3000 tonnes of biodiesel is produced from recycled frying oil. Technology developed by BioDiesel International GbH allows easy processing of any virgin or waste oil or fat of animal or vegetable origin, into standardises biodiesel. Biodiesel is marketed as B100 or as a voluntary blend of up to B3. As of 2000, biodiesel achieved full tax exemption from the existing mineral-oil tax. The current tax on fossil diesel is approximately € 0.28/L. Distributor prices (as of March 2000) were between € 0.487 to 0.465 per litre, compared to fossil diesel at € 0.513 per litre. Biodiesel in Austria is primarily in use in bus fleets, taxi fleets and some regional government car fleets.
France Production capacity of 440,000 tonnes per year. The French market is characterised by strong involvement by refineries in biodiesel production. B5 is the predominant blend used in France, with some regional councils blending at up to B30 for captive fleets. Long-term tests have lead to existing guarantees being extended to cover biodiesel by PAS Peugeot Citroen and Renault IV. As the great majority of biodiesel in France is blended in with diesel as B5, it has effectively become anonymous and public awareness of the biodiesel is not high. Biodiesel production is controlled by a standard set by “Journal Officiel”.
Ireland Cork County Council operates a number of their vehicles on biodiesel.
Italy Production capacity of 350,000 tonnes per year. Approximately half of the Italian biodiesel production is used as heating oil, with the remainder blended at B5 with fossil diesel as a low sulphur and lubricity additive. Legislation passed in February 1999 mandates that biodiesel must be used in public transport in cities of greater than 100,000 people. Biodiesel standards are mandated under the UNI 10946 standard for vehicle uses, and UNI 10947 standard for heating use.
Luxembourg
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A total of 45 public city transit buses are operating on biodiesel.
Portugal As of 2002, no biodiesel is produced in Portugal.72 Approximately 24 vehicles operate on biodiesel (soy methyl ester) at between B5 and B30 in captive transport fleets. Liquid biofuels are not price competitive in Portugal due to the lack of fiscal incentives.
Sweden Production capacity of 30,000 tonnes per year. More than 400 buses operate on biodiesel throughout the country.
United States of America (Provided by Steve Howell, MARC-IV Consulting) In the US, public interest in a cleaner environment and reduced dependence on foreign oil has recently given rise to several pieces of nation wide legislation and government sponsored initiatives. The most important has been the passage of the Clean Air Act Amendments of 1990 and the Energy Policy Act of 1992 and the biodiesel specific Energy Conservation Reauthorisation Act of 1998. Embedded in this legislation are a variety of programs encouraging the use of clean burning fuel sources and the development of domestic alternatives to diesel. More recently, electricity blackouts in California in 2000 and 2001 as well as the tragic events of September 11, 2001 have spurred a renewed interest in finding new, domestic sources for energy in the US. During this same period, American soybean farmers also became interested in alternative uses for soybean oil due to a carry over of excess soybean oil in the market each year, a reduction in US government export support for soybean oil, and the signing of what some farmers consider restrictive international trade agreements (such as GATT). The culmination of these independent factors has spurred on the interest in biodiesel in the US and the formation of the National Biodiesel Board; a trade association dedicated to the research and commercialisation of biodiesel. The NBB and a coalition of other agricultural related trade groups, primarily the American Soybean Association, has been the driving force for beneficial legislation in over 20 states and the inclusion of biodiesel into the energy bill currently in conference between the US House of Representatives and the US Senate.
US Market Summary Penetration of biodiesel in the US market is still small. The approximate annual consumption of biodiesel in the US is 95 million litres per year, compared to a total diesel consumption of 204 billion litres per year. Some key US market figures are
Total diesel distillate fuel use is 54 billion gallons per year (204.4 billion litres per year)
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On road diesel distillate use is 30 billion gallons per year (113.6 billion litres per year)
Current biodiesel sales are 25 million gallons per year (94.6 million litres per year)
Installed biodiesel production capacity is 200 million gallons per year (757.1 million litres per year)
Potential biodiesel from existing feedstock sources is 2 billion gallons per year (7.6 billion litres per year)
US Department of Energy Target is 8 Billion gallons per year. (30.3 billion litres per year)
The breakup of the biodiesel market is approximately 24% B5/B2, approximately 75% B20 and approximately 1% B100. Approximately 75% of all biodiesel use in the US is for public transport uses, and the remainder for private use.
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APPENDIX C - BIODIESEL PRODUCTION Appendix C Figure 1 shows the simple version of the catalysed transesterification reaction of vegetable oils (National Biodiesel Board, 2002)74, while Appendix C Figure 2 shows the reaction mechanism. Appendix C Figure 1: Transesterification of triglycerides – the biodiesel reaction
Feedstock (Triglyceride)
Alcohol Glycerol Mono alkyl esters(Biodiesel)
Appendix C Figure 2: Reaction mechanism for the transesterification of vegetable oils
(Source: Schuchardt, U., Sercheli, R. & Vargas, R.M., (1998). Transesterification of Vegetable Oils (a Review), J. Braz. Chem. Soc., Vol. 9, No. 1, Brazil, pp. 199 – 210).73
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Reaction step (1) shows the alcohol and the catalyst (B, base) reacting together, where ROH is the alcohol. R is the generic chemical symbol for an alkyl group. In this case, R is the methyl group (CH3) for methanol, and the ethyl group (CH3CH2) for ethanol. Reaction steps 2 and 3 show the alcohol species attacking the carbonyl (C=O) double bond of the triglyceride group. Reaction step 3 shows the product ROOCR’’’. This is one of the mono alkyl esters formed from the original triglyceride, where R has come from the alcohol reagent and R’’’ from the triglyceride. Reaction step 4 shows the regeneration of the catalyst and the formation of a diglyceride alcohol. The reaction steps 1-4 repeat until the triglyceride is consumed. The final products, using the above nomenclature are:
ROOCR’’’, ROOCR’’ and ROOCR’. These are the mono alkyl esters of long chain fatty acids (biodiesel). R has come from the alcohol reagent, and R’, R’’, and R’’’ have come from the original triglyceride; and
OH-CH2-CH(OH)-CH2-OH, glycerol.
Industrial scale production of biodiesel The industrial scale production of biodiesel can be described by a process flow diagram as shown in Appendix C Figure 3. (National Biodiesel Board, 2002)74. Reference is made in Appendix C Figure 3 to the use of methanol, but the overall concept is the same regardless of the alcohol reagent used. Appendix C Figure 3: The biodiesel production process (National Biodiesel Board, 2002)74
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Biodiesel production generally occurs in the following stages:
The alcohol and catalyst (typically methanol and potassium hydroxide, respectively) are mixed in a standard agitator or mixer.
Feedstock is added to a closed vessel containing the alcohol/catalyst mixture. The reaction is often heated to approximately 70°C to speed the reaction. Reaction times are generally from 1 to 8 hours. Excess alcohol is normally added to ensure the reaction proceeds to completion.
The biodiesel and glycerol are separated under gravity, as glycerol is denser than biodiesel. A centrifuge to speed separation can also be used in this stage.
The excess alcohol is separated from both the glycerol and biodiesel phases by evaporation under low pressure (flash evaporation) or distillation. Excess alcohol is reused.
Unused catalyst in the glycerol is neutralised by the addition of acid. The salt that is formed in this stage (for example, potassium sulphate if the catalyst is potassium hydroxide and the acid is sulphuric acid) is recovered and can be used as fertiliser.
The alkyl esters (biodiesel), in some production processes, are occasionally purified by a gentle warm water wash to remove residual catalyst or soaps.
An example of the stoichiometry for the reaction is that 100 kg feedstock will react with 10 kg of alcohol to produce 10 kg of glycerol and 100 kg of biodiesel.
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APPENDIX D - EFFECTS OF DIFFERENT FEEDSTOCKS ON BIODIESEL FUEL PARAMETERS Biodiesel is composed of various fatty acid esters of varying carbon chain length and with different proportions of double bonds in each fatty acid ester. Traditionally rapeseed oil has been the major feedstock for Europe and soybean oil for the US for biodiesel production. Canola oil (low-erucic rapeseed oil) is seen in Australia as a viable renewable vegetable oil feedstock pending favourable commodity prices.
Countries in tropical climates prefer to utilise coconut oil or palm oil. Other vegetable oils, including sunflower, safflower, etc have been investigated. These oils along with other lower cost feedstocks such as tallow and waste cooking oil represent a small portion of the current worldwide production of biodiesel. With increasing development of the biodiesel industry and improvements in technology potential exists for the use of these lower cost feedstocks to increase. Australian industry interests in biodiesel are looking at tallow and waste cooking oils as well as canola as feedstocks.
Anecdotal evidence suggests that a biodiesel plant designed to process tallow (high saturated feedstock) will have the flexibility to process other less saturated feedstocks (polyunsaturated plant derived oils). In general biodiesel is composed of a combination of the following fatty acid esters:
C12:0 and C14:0; C16:0 and C16:1; C18:0 , C18:1, C18:2, C18:3; and C20 and C22:1.
Research indicates that the different proportions of fatty acids found in different feedstocks influence some biodiesel fuel properties.13 Knothe et al33 report that the iodine number of alkyl esters is approximately the same as their parent oils. The iodine number is a measure of unsaturation, therefore, the degree of unsaturation of alkyl esters is approximately the same as their parent oils. There are a few important parameters, which are influenced by the type of feedstock used, and depending on wanted or regulated properties there is some flexibility in choice of various feedstock types available and in the opportunity of blending for optimising properties wanted. The following properties have to be observed.
Content of saturated, mono-, di-, and polyunsaturated fatty acids Historically vegetable oil as produced by 00-rapeseed or canola was used as the feedstock of choice in the beginning of biodiesel-production. 00-rapeseed oil has a high erucic acid (C 22:1) content of up to 60% and is low in saturated fatty acids, giving it good stability and cold flow properties. Further, rapeseed oil has a low level
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of glucosinolate, which is an undesired components in the meal. New technology has further enhanced yield and rapeseed quality and rapeseed oil is now the most common feedstock for biodiesel production.75 It can be generally said that the more saturated fatty acids (palmitic acid 16:0, stearic acid 18:0) that are present:
the higher the biodiesel stability (oxidation stability, thermal and storage stability);
the lower the probability to form polymerised molecules under high temperatures and pressure (e.g. when unburned traces of biodiesel are washed down into the engine crankcase and exposed to high stress levels caused by high temperature and pressures);
the higher the cetane-number for better engine performance; and the higher the CFPP (cold filter plugging point) with a worse winter
operability. and vice-versa. Biodiesel stability is currently measured using the iodine number. The iodine number for biodiesel is effectively the sum of the iodine numbers of the individual fatty acids. Iodine number is not an ideal parameter as it measures only the average unsaturation of an oil. The iodine number of a 00-rapeseed oil of acceptable stability could be reached as well by blending an oil with an unusual high content of polyunsaturated fatty acids (e.g. linseed oil) together with an oil with a high content of highly saturated fatty acids (e.g. palm oil) and thus does not express the potential risk of instability represented by this blend.75 Oxidation stability is measured in addition to the rather weak iodine number parameter as one measure to limit potential risks from vegetable oils with a high content of polyunsaturated oils. New stability parameters will be published upon conclusion of the BIOSTAB project as coordinated by BLT-Austria, the Federal Institute for Agricultural Engineering, by early 2003.75 Pacific Air & Environment approached the BIOSTAB project team for preliminary results but none were made available. There is no perfect oil available yet and the Biodiesel producer is faced with a clear trade-off decision between desired and undesired properties thus optimising the finally produced Biodiesel. New oilseed varieties with improved fatty-acid-profiles are already available and will lead to quality improvements of Biodiesel, as shown in, eg:
High oleic (HO) rapeseed with an oleic acid content of more than 80%; and
Low linolenic (LL) rapeseed with a linolenic acid content of less than 4%.
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Content of short-chain vs. long chain fatty acids Another variable parameter is the chain-length of the fatty acids. Generally it can be said that the shorter the chain length:
the higher the oxygen content for improved combustion and lower emissions, but also for a lower caloric value resulting in a lower performance level;
the lower the CFPP (Cold Filter Plugging Point) with improved winter operability; and
the lower the boiling line resulting in reduced HC- and PM-emissions will be
and vice-versa.75
Appendix D Table 1: Trading rules for short chain and long chain fatty acids in biodiesel.75
Increasing SHORT
CHAIN proportion Increasing LONG CHAIN
proportion Parameter Oxygen content higher lower Emissions (particulate matter, soot, hydrocarbons)
reduced ☺ increased
Caloric value (performance) lower higher ☺ Combustion improved ☺ worse Boiling point lower higher CFPP lower higher winter operability better ☺ worse ☺ Desirable property
Appendix D Table 2 : Trading rules for saturated and unsaturated fatty acids in biodiesel.75
Increasing
SATURATION Decreasing
SATURATION Parameter CFPP higher lower winter operability worse better ☺ Cetane number higher lower engine performance higher ☺ lower Iodine value lower higher oxidation stability better ☺ worse polymerisation lower ☺ higher ☺ Desirable property
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Summary Appendix D Table.3 summarises the effect of changing feedstocks and alcohols on typical biodiesel fuel.33
Appendix D Table 3: Typical Fuel Properties of Several Fatty Acid Alkyl Esters Ester CN
(a) ( - )
IV (b)
( - ) HV (c)
(kJ/kg) Viscosity
(mm²/s) CP
(d)
(°C)
PP (e)
(°C)
FP (f)
(°C)
Methyl Cottonseed 51.2 90 – 199 - 6.8 - -4 110 Rapeseed 54.4 94 – 120 40449 6.7 -2 -9 84 Safflower 49.8 126 – 152 40060 - - -6 180 Soybean 46.2 117 – 143 39800 4.08 2 -1 171 Sunflower 46.6 110 – 143 39800 4.22 0 -4 - Tallow 56 -
60 35 – 48 39949 4.11 12 9 96
Waste oil (g) 49.0 99 – 117 - 7.72 3 -3 - Ethyl Palm 56.2 35 – 61 39070 4.5 8 6 19 Soybean 48.2 117 – 143 40000 4.41 1 -4 174 Tallow - 35 – 48 - - 15 12 Propyl Tallow - 35 – 48 - - 17 12 - Isopropyl Soybean 52.6 117 – 143 - - -9 -12 - Tallow - 35 – 48 - - 8 0 - n-Butyl Soybean 51.7 117 – 143 40700 5.24 -3 -7 185 Tallow - 35 – 48 - - 13 9 - 2-Butyl Soybean - 117 – 143 - - -12 -15 - Tallow - 35 – 48 - - 9 0 -
a. CN = cetane number b. IV = iodine value (assumed from feedstock iodine values based on Knothe et
al.33 c. HV = heat value d. CP = cloud point e. PP = pour point f. FP = flash point
(Source: Mittelbach et al77 and Körbitz75). Since vegetable oils are not economically competitive with mineral based diesel products, the use of used frying oils for biodiesel production has been investigated. The production of biodiesel from waste cooking oils appears to be the most attractive alternative for waste treatment. However, at the most it is estimated that only 1 – 2 % of the diesel demand could be covered by waste cooking oils.
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Mittelbach et al77 reported that under normal conditions approximately 2-10% of triglycerides in the original vegetable oil are oxidised in the process of cooking. This level of triglyceride oxidation can still produce biodiesel to current worldwide standards.78 However, the main parameters for a simple transesterification process are not only the chemical changes of the fatty acid chains, but the content of water and free fatty acids, which can require costly purification steps.77 The water content of waste cooking oil can vary significantly depending on the cooking process, storage conditions, and thermal decomposition. Mittelbach et al77 reports a range of water contents for waste cooking oils of between 0.05% and 1.96%. The content of free fatty acids in waste cooking oil is reported to be between 0.26% and 2.12%. These are typical values for all vegetable oils.
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APPENDIX E – IMPACTS OF BIODIESEL ON DIESEL ENGINE OIL The United States National Biodiesel Board74 performed a review of engine oil impact from biodiesel use. The study involved examining parameters outlined below to determine whether biodiesel fuelling was a trigger mechanism that resulted in the polymerisation of lubricating oil.
Iodine number The iodine number of the oil is normally associated with the potential for the oil to polymerise, as it is a measure of the proportion of unsaturated bonds. The draft European biodiesel fuel standard limits the iodine value to <120. According to Schafer44, the use of biodiesel with an iodine number that exceeds 115 increased the risk that the engine lubricating oil will polymerise over time. Recent research indicates there are limitations of using the iodine number to determine the risk of engine oil polymerisation. Prankl and Worgetter43 showed that the increase in oil viscosity is only slightly dependent on the iodine number of the fuel. Furthermore, the viscosity of the engine oil varied only slightly when engines were fuelled with methyl esters with an iodine number ranging from 100 to 140. The review performed by the United States National Biodiesel Board showed that the iodine number can provide some indication of the potential for a given methyl ester fuel to polymerise in the engine lubricating oil.42 However, biodiesel fuels with an iodine number of 100 to 140 do not show substantially different rates of engine oil polymerisation. Therefore, limiting the iodine value in order to control the potential for biodiesel to polymerise in the engine lubricating oil may not be effective.
Viscosity The effect on engine oil viscosity when fuelled with biodiesel is for an initial slight decrease in viscosity to be followed by a rise in viscosity.42 Research shows that the use of a methyl ester fuel will result in a minor engine oil dilution, but not to the extent that recommended limits will be exceeded. Trials performed on French bus fleets fuelled with rape methyl ester and RME blends showed only a minor decrease in lubricating oil viscosity.79 No oil thickening occurred with mean oil change intervals of between 20,000 and 22,000 km.79 Furthermore, the oil consumption rate was constant over these trials. In the reviewed literature viscosity was the most frequently used quantifier of lubricating oil polymerisation. Du Plessiss et al63 concludes that there is a direct relationship between an increase in engine oil viscosity and oxidation parameters. Lubricating oil in petroleum diesel fuelled engines tend to thicken due to a soot-mediated oil thickening process.80,81 Also, different engines produce different amounts of soot and have different rates of soot-mediated oxidation in the lubricating oil. Therefore, viscosity is a potential indicator of biodiesel fuel dilution however its ability to predict the polymerisation rate remains unsubstantiated. Thermal oxidation can also contribute to increasing the viscosity of engine oil.
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All vegetable oil derived methyl ester fuels has the potential to cause an increase in engine oil viscosity.42 However, there are substantial differences between alkyl esters derived from different vegetable feed stocks. Honary82 states that the viscosity change is on average 20 times greater for soybean oil compared to rapeseed oil.
Oil Change Interval Engine oil viscosity increase in biodiesel fuelled engines over time is suspected to be caused from polymerisation of the engine oil from the biodiesel.42 Therefore, the oil change interval is an important factor to consider when evaluating the impact on engine oil from biodiesel. Engine oil viscosity increases towards the end of a 250 hour oil change interval for soybean oil methyl esters.83 Trials of 90 hour oil change intervals have not observed viscosity increases.42 Some engine manufacturers in the United States have suggested/recommended halving the oil change interval to 125 hours for rape see oil methyl esters to reduce the chance of an increase in viscosity beyond the SAE classification. In addition, some engine manufacturers view soybean oil methyl esters as representing a greater risk of causing lubricating oil problems than rapeseed oil methyl esters.44
Oil Type Research shows that the engine oil SAE classification does not appear to influence the viscosity or polymerisation of engine oil in biodiesel fuelled engines. Developments in synthetic diesel engine oil are promising as synthetic base stocks typically show much better control of fluctuations in oxidation and viscosity.42
Method of Injection (Indirect Injected vs. Direct Injected) More lubricating oil dilution was reported with direct injection engines than with indirect injection engines in a review performed by the United States National Biodiesel Board.42 Diesel engines fuelled with rapeseed methyl esters which had a modern high pressure fuel injection system had much lower fuel dilution in the lubricating oil than did older fuel injection engines.42 Ethyl esters of soybean oil have been reported to cause ester contamination of the crankcase lubricant, which is unacceptably high in direct injection engines.84 Research with soy methyl ester fuelled diesel engine lubricating oil did not show a significant decrease in viscosity with an oil changeover of approximately 90 hours.42 However, there is little data available for soy methyl ester fuelled engines with an oil change of greater than 100 hours.42
Feedstock Effect on Biodiesel Research shows that an increased rate of lubricating oil polymerisation is expected where alkyl esters derived from oils with higher levels of unsaturation were used.42
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Furthermore, methyl esters have been shown to have higher quantities of tocopherols than ethyl esters.63 As mentioned previously, tocopherols are naturally occurring antioxidants that cause the induction period of the polymerisation reaction to take longer. Therefore, methyl esters are more stable than ethyl esters.
Blend of Biodiesel Used Soybean and rape derived fuels showed a decrease in lubrication oil thickening when the fuel was a 50% or less blend of biodiesel.79,85
Engine Duty Cycle There is little information regarding engine duty cycle and the effect on diesel engine oil. Worgetter85 reports that the effect on rapeseed methyl ester dilution of the lubricating oil is more dependent on the load and less dependent on the speed from experiments performed on a typical Austrian tractor under ten load/speed settings.
Oxidation Stability Du Plessis et al63 showed that methyl esters are more stable to air oxidation than ethyl esters. This has been attributed to the higher yield of naturally occurring antioxidants, tocopherols, through the esterification process. Antioxidants increase the oxidation stability of biodiesel fuels. Antioxidants can be added to alkyl ester fuels to increase the oxidative stability of the fuel if required.
Engine Oil Acid Value The polymerisation of the engine lubricating oil does not appear to affect the acid number of the lubricating engine oil until after the viscosity of the oil has exceeded operating values.42 Therefore, the engine oil acid number cannot be used to determine the extent of engine oil polymerisation.
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