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Biodiesel and engine lubrication 1

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    Biodiesel and engine lubrication 1 Biodiesel and engine lubrication 1 Document Transcript

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    • Published by Chevron Products Company CONTENTS 6101 Bollinger Canyon Road San Ramon, CA 94583 Contributor and Acknowledgements ............. 1 To request a new subscription or to report a change of address, please send inquiries to: LubricationMagazine@ What is Biodiesel? ........................................ 2 salessupport.com or call (800) 533-6571. Why is Biodiesel of Such Global Lubrication is a registered trademark of Chevron Intellectual Property, L.L.C. and is used with permission. Interest and Importance? ............................... 3 COPYRIGHTS: Biodiesel Production Process ........................ 5 © 2007 by Chevron Products Company, San Ramon, CA. Biodiesel Feedstacks ...................................... 7 All rights reserved. The contents of Lubrication cannot be reprinted without the Feedstacks In uence express written permission of Chevron Products Company. Biodiesel Properties ....................................... 9 Managing Editor: Micah Berry, North American Lubricants Challenges of Biodiesel .................................. 9 Design by: Marketing Group West Second Generation Biodiesel ABSTRACT and Biomass-to-Liquid (BTL) There is a global interest in the use of alternative fuels due to or “Renewable Diesel” ................................ 11 the desire for energy independence, the high cost of petroleum- derived fuels, and environmental concerns such as greenhouse gas National Biodiesel Accreditation emissions. Of particular interest is the use of biodiesel (esters of Program BQ-9000 ....................................... 12 vegetable oil) which can be produced in all regions of the world, and is increasingly used in passenger cars as well as heavy-duty Original Equipment vehicles equipped with diesel engines. Manufactures and Biodiesel ........................ 13 Until now, much of the primary research has focused on process technologies to produce biodiesel from sources such as soy, palm, OEM Concerns with Biodiesel .................... 14 rapeseed, coconut and jatropha curcas. There have also been studies looking at the impact of biodiesel use on exhaust emissions, vehicle Summary ..................................................... 16 driveability, fuel economy, and fuel system compatibility. There is limited data on the impact of biodiesel use on engine lubrication. In this two-part series of Lubrication Magazine, we will rst discuss biodiesel composition, feedstocks and production techniques. We will also identify the primary bene ts of biodiesel, as well as some of the concerns and challenges faced by the biodiesel industry. In addition, we will review the existing and emerging regulations that mandate the use of biodiesel in various regions of the world, as well as the Original Equipment Manufacturers’ (OEM) positions regarding biodiesel use. In the second issue, we will explore the impact of biodiesel use on engine lubrication through the use of bench tests, laboratory engine tests and real-world experience from eets. Data will be included based on tests with biodiesel blends derived from soy, rapeseed, palm and coconut. We will also brie y discuss ways in which lubrication additive technology can help fortify the performance of the crankcase oil in order to counteract the effects of biodiesel use, such as increased oil oxidation and piston deposit formation.
    • CONTRIBUTOR Gary M. Parsons | Global OEM and Industry Liaison Manager Chevron Oronite LLC Products and Technology Gary joined Chevron in 1981 after obtaining his Bachelor of Science and Master of Science degrees in Mechanical Engineering from the University of California at Berkeley. From 1981 through 1985, Gary worked as a Research Engineer in the Fuels Division at Chevron Research and Technology Company. From 1986 through 1995, Gary was the Oronite Additives Fuels Product Manager in three different assignments in Europe, North America, and Asia. In 1995, Gary took the role of Asia Paci c Region Lubricants Specialist for Oronite Additives. In 1999, Gary joined Chevron Products Company as an Account Manager in the Strategic Accounts Group. In October 2000, Gary was selected as a Market Manager in the Commercial Automotive Group of Chevron Products Company. Since the merger between Chevron and Texaco in 2001, Gary has served as the Global Consumer Transport Segment Director and as Commercial Automotive Business Unit Manager. Gary was named Global OEM and Industry Liaison Manager, Chevron Oronite LLC in January 2005. Gary has been a member of the Society of Automotive Engineers (SAE) since 1981. Acknowledgements We would like to acknowledge the following subject matter experts who contributed valuable input and content for this article. Isabele Araujo, Technology Support Manager – Texaco Brazil Richard van den Bulk, Chevron Oronite Europe Passenger Car OEM representative Arnoud de Vries Feyens, Chevron Oronite Europe Heavy-Duty OEM representative Roger Organ, Chevron Products Company Technical Advisor Rajesh Paulose, Global Product Line Manager, Biofuels – Chevron Products Company Frank Stunnenburg, Managing Director, Chevron Oronite Technology Netherlands Jan Peters, Automotive Engine Oil Research Engineer, Chevron Oronite Technology Netherlands Mark Cooper, Automotive Engine Oil Development Engineer, Chevron Oronite San Antonio 1
    • Part I part of the solution for complying with worldwide federal mandates to prevent and This is the rst part of a two-issue series on biodiesel. Part I contains background reduce pollution, diversify fuel sources and information on biodiesel feedstocks, increase energy ef ciency and sustainability. production and properties, plus Original What is Biodiesel? Equipment Manufacturers’ concerns regarding According to the U.S. National Biodiesel biodiesel use. Part II will provide laboratory Board (NBB), the terms “biodiesel” and and engine test data in which certain aspects “biodiesel blend” have speci c technical of biodiesel use are evaluated with respect to de nitions approved by ASTM International. engine lubrication. Biodiesel, n—a fuel comprised of mono- Why All the Buzz About Biodiesel? alkyl esters of long chain fatty acids derived Today, countries worldwide are actively from vegetable oils or animal fats, designated pursuing the development of programs to B100, and meeting the requirements of promote the production and use of biodiesel, ASTM D 6751. a renewable fuel for diesel engines derived Biodiesel Blend, n—a blend of biodiesel fuel from a variety of plant oils and/or animal meeting ASTM D 6751 with petroleum- fats, or recycled cooking oils. Common based diesel fuel, designated BXX, where XX plant-based feedstocks for biodiesel include represents the volume percentage of biodiesel soybeans, rapeseed, palm, corn, coconut and fuel in the blend. jatropha. Animal fats include pork lard, beef tallow, sh oil and poultry fat. The third Biodiesel blends may contain biodiesel in source of feedstocks includes “ oat grease” varying concentrations from one volume from wastewater treatment plants and trap percent (B1) to 100 volume percent (B100). grease from restaurants, in addition to used Diesel engines are capable of running on cooking oils. By some de nitions, biodiesel is B100, although the practice is strongly considered to be biodegradable and suitable discouraged by engine manufacturers, for for sensitive environments. Biodiesel is a reasons that will be explained later in this signi cant energy resource that may provide article. Typically dependent on blend credits Emissions Biodiesel System Specifications Durability Government Regulations OEM Warranty Tax Coverage Incentives Process Impact Quality on Drain Certification Intervals g s ggin ial ty r Plu Low ter bili Filte Temp Ma pati m Co Handling or ect Inj osits p on De ati Oxid ution Co l Dil Fue rr os Pisto io N n De Emis Ox posit n sion s dge s Slu Emerging Biodiesel Market: Solving the Puzzle to Allow a Smooth Introduction 2
    • CO2 Well-to-Tank Tank-to-Wheels Well-to-Wheels Analysis-Petroleum System. Hydrocarbons Extracted from the Earth are Burned, Creating CO2 Emissions and taxation, the most popular biodiesel a country’s trade balance and enables funds blends currently used in the U.S. are B2, B5, spent on imported petroleum to be reserved B11 and B20. within the national economy. According to the In addition to “biodiesel,” there is “renewable International Energy Agency (IEA), the U.S. diesel,” which perhaps holds greater promise in consumes approximately 20 million barrels of the long term. The above represents the ASTM oil a day (or 840,000,000 gallons), more than de nition for biodiesel produced through a half of which is imported. By 2025, demand transesteri cation process to create a Fatty Acid is expected to rise to 26 million barrels a day, Methyl Ester (FAME). However, it is important of which 60 percent will be imported, states to understand that biomass can be handled the U.S. Energy Information Administration and treated differently in other processes to (EIA). Annual expenditure on imported oil create products that are not fatty acid methyl is now approximately 250 billion dollars. esters (FAME and mono alkyl methyl esters are Moreover, this gure is increasing with the identical). These other processes do not produce steady rise of oil prices to the $90/barrel range. mono alkyl methyl esters, and are described In addition to trade issues, fossil fuel alone later in this paper. They create products that are cannot meet the projected global demand for essentially straight chain saturated C15 and C17 liquid transportation fuels, meaning there alkyl chains, and are referred to as “renewable is a shortfall. To make up for this shortfall, diesel.” There are on-going debates regarding all forms of alternative sources are needed, whether or not renewable diesel should also including biofuels. enjoy the incentives and subsidies designated speci cally for mono alkyl ester biodiesel. The An additional motivation for the focus on following discussion will, however, focus on biodiesel is the need to conserve the world’s biodiesel in the fatty acid methyl ester form. existing conventional fuel supply, which is currently being depleted at escalating levels So why is biodiesel of such global interest each year. Fossil fuels such as diesel are non- and importance? renewable, meaning that once their existing Political and Economic Bene ts – Biodiesel supplies are exhausted, they are gone forever. promotes a nation’s energy security by making Biodiesel, on the other hand, is created the nation more self-reliant and helps expand from renewable resources that continue indigenous supplies of fossil fuels. Whether to be cultivated season after season, such factual or not, there is also the common as oils generated by plants from sunlight belief that use of renewable fuels can improve and air and fats produced by animals when 3
    • CO2 CO2 CO2 CO2 Solar Energy Biodiesel CO2 Harvesting Processing Distribution Use as Fuel Photosynthesis Biodiesel Facility Converts Vehicles Burn Converts CO2 Feedstock to Biodiesel to to Feedstock Biodiesel & CO2 Release CO2, Which is Recycled Well-to-Wheels Analysis – Biodiesel System CO2 is consumed during Photosynthesis, Offsetting Some CO2 Emissions they consume food. Renewable fuels are However, some studies have shown that the use considered more sustainable, as long as of biodiesel does increase the oxides of nitrogen they are manufactured in an ecologically (NOx) emissions in most cases. and environmentally acceptable way. Agricultural Bene ts – Biodiesel’s primary Emissions and Environmental Bene ts feedstocks are soybean oil in the U.S. and – Biodiesel reduces global warming gas Brazil, rapeseed oil in Europe and palm oil emissions such as carbon dioxide (CO2) due in Asia. With this important new end-use for to its closed carbon cycle. When biodiesel these and other crops (such as jatropha, corn, is harvested, processed and burned, some cottonseed, etc.), there is enormous potential of the CO2 released into the atmosphere is to stimulate global agricultural economies. recycled by growing plants. These plants are Conversely, there are growing concerns later themselves processed into biodiesel, and regarding competing applications of edible the cycle continues. With fossil fuels, on the feedstocks for food versus renewable fuels. other hand, 100 percent of CO2 generated These concerns will be addressed further in escapes into the atmosphere. According to a this paper, in the section on feedstocks. 1998 biodiesel lifecycle study sponsored by Health Bene ts – Scienti c research has the U.S. Department of Energy (DOE) and shown that compared to petroleum diesel the U.S. Department of Agriculture (USDA), exhaust, biodiesel emissions have lower levels biodiesel reduces net CO2 emissions by 78 of harmful polycyclic aromatic hydrocarbons percent compared to petroleum diesel. The (PAH) and nitrated PAH compounds. These reason it does not reduce CO2 emissions by compounds have been identi ed as potential 100 percent is that fossil fuels are utilized in carcinogens that can adversely affect biodiesel production. Based on these results, reproductive, developmental, immunological the NBB has deemed biodiesel an effective and endocrine systems in both humans and greenhouse gas mitigation strategy for wildlife. According to the DOE, using B100 medium and heavy-duty vehicles. can help to lower these toxins by up to 90 According to the NBB, compared to emissions percent, whereas using B20 can eliminate from diesel fuel, biodiesel also helps reduce ozone 20-40 percent of them. forming hydrocarbon (HC), poisonous carbon Furthermore, in 2000, biodiesel became the monoxide (CO) and hazardous diesel particulate only alternative fuel to have successfully matter (PM). Plus, biodiesel virtually eliminates completed the Tier I and Tier II health acid rain-causing sulfur dioxide emissions. effects testing of the 1990 Clean Air Act 4
    • Amendments. Test results demonstrated that aggressive towards certain elastomers and biodiesel has a non-toxic effect on health. seals. Therefore, older fuel systems and distribution systems need to be inspected Fuel System Lubricity Bene ts – As an and modi ed before biodiesel can truly be ester, Biodiesel possesses favorable lubricity considered a “drop in” technology. properties, which is important since all diesel fuel injection equipment relies somewhat on fuel Biodiesel Production Process as a lubricant, especially rotary and distributor The two ASTM technical de nitions limit type fuel injection pumps. Low lubricity fuel the use of the term “biodiesel” to fuel that causes increased wear and consequently is produced when a plant oil or animal fat reduced component life. Biodiesel also contains is subjected to a transesteri cation process, less than 15 parts per million (ppm) of sulfur. resulting in Fatty Acid Methyl Ester (FAME) The introduction of ultra-low sulfur diesel with combustion properties very similar to fuel (ULSD) renders biodiesel’s lubricity of those of petroleum-based diesel fuel. This even greater signi cance, since ULSD as FAME constitutes biodiesel. A byproduct of produced in the re nery can sometimes have this process is glycerin, which is removed. poor lubricating properties, although this is Transesteri cation requires mixing the oil easily recti ed in terminals by the addition or fat with an alcohol in the presence of a of lubricity additive. According to the NBB, catalyst. Alcohol choices include methyl, bench scale testing has shown that even low- ethyl, propyl or butyl alcohols. Since methyl level biodiesel blends such as B1 and B2 can alcohol (methanol) is the most cost-ef cient, improve lubricity up to 65 percent without the it is the most popular choice. It also enables need for additional lubricity additives. easier separation of the nished product Ease of Use and Safety Bene ts – Biodiesel from reaction byproducts. Depending on blends of B20 or less are literally a “drop in” the alcohol used, the resulting biodiesel technology, according to the DOE. However, will be a methyl ester, ethyl ester, propyl or not all Original Equipment Manufacturers butyl ester respectively. Common catalysts (OEMs) agree with this assessment, as will include sodium hydroxide and potassium be noted later. Biodiesel blends can be used hydroxide. In the U.S., the main form of in most diesel equipment with few, if any, biodiesel is methyl soyate or soydiesel, formed modi cations, and can also be used in the by reacting methanol with soybean oil. The existing diesel fuel storage and distribution transesteri cation process reacts 100 units infrastructure. Plus, biodiesel is safer to (by weight) of feedstock with 20 units of use than petroleum diesel; the ashpoint short-chain alcohol such as methanol in the for pure biodiesel (B100) is at least 260˚F presence of a catalyst, yielding approximately (130˚C), versus a minimum of 125˚F (52˚C) 100 units of biodiesel, 10 units of methanol for standard diesel. On the other hand, it (recovered from reaction) and 10 units of must be noted that biodiesel (B100) is more crude glycerin. Typical Biodiesel Transesteri cation Process 5
    • Biodiesel Standards values for properties such as viscosity and In 2001, the ASTM approved the standard ash point, the most important distinction for biodiesel, designated ASTM D 6751. This between the two is the measurement of standard pertains to pure biodiesel, known oxidation and polymerization. Unsaturated as B100, for use with petroleum diesel blends oils oxidize faster and polymerize more up to 20 percent by volume. Currently, work rapidly than saturated oils. The Iodine Value is underway to incorporate B5 into D 975, (IV) measures the level of unsaturation the petroleum diesel speci cation, as well in biodiesel. Consequently, a higher IV as to develop separate speci cations for indicates a higher level of unsaturates, which biodiesel blends between B6 and B20. Not in turn indicates an increased tendency to wanting to wait for an of cial ASTM B20 oxidize and polymerize. While EN 14214 speci cation, on May 31, 2006, the Engine establishes a maximum IV of 120 as well Manufacturer’s Association issued a “Test as an additional oxidation parameter called Speci cation for Biodiesel Fuel” and has an Oxidative Stability Index, ASTM D 6751 encouraged producers and users to follow does not incorporate an IV. However, it has it until an of cial ASTM speci cation is recently been revised to include a three- issued. The federal government has made hour oxidation stability requirement. EN ASTM D 6751 part of the of cial de nition 14214 incorporates a more severe six-hour of biodiesel in the Energy Policy Act of 2005. requirement. Since the soy methyl ester Additionally, biodiesel, as de ned in D 6751, produced in the U.S. has a higher IV than is registered with the EPA as a fuel and a fuel the rape methyl ester in Europe, 130 versus additive under Section 211(b) of the Clean 100 approximately, pure soybean oil methyl Air Act. ester does not meet the requirements of EN 14214. With the looming shortage in Europe The European standards organization, of rapeseed for biodiesel, EN 14214 may be Comité Européen de Normalisation (CEN) relaxed to allow for the import of a wider has also developed a performance standard range of biodiesel feedstocks, such as soy for biodiesel fuel, EN 14214, which is methyl ester. Currently, however, palm oil is considered to be stricter than ASTM D being imported from Asia to make up for the 6751. Its criteria are most easily met by shortfall in rapeseed. methyl esters manufactured from rapeseed, which is the most common biodiesel Across the globe, many countries have feedstock in Europe. Although EN 14214 either simply adopted the U.S. or European and ASTM D 6751 establish different speci cations, or adjusted them to t their ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Biodiesel is a Global Phenomenon 6
    • needs. For instance, although Canada supports 84 million metric tons (mt) of soybeans. ASTM D 6751, it has established a speci cation Brazil was a close second with 57 million for biodiesel blends B1 through B5 called CAN/ mt. These gures are projected to increase CGSB – 3.520 “Automotive Low Sulphur Diesel yearly as additional acreage is devoted to soy Fuel Containing Low Levels of Biodiesel Esters production to meet the rapidly rising demand (B1-B5).” Australia, Indonesia and Brazil’s for biodiesel. However, a potential issue here biodiesel standards are a combination of is that both the U.S. and Brazil also have ASTM D 6751 and EN 14214. Japan’s biodiesel competing needs for ethanol, which requires standard, JASO M360, is based on EN 14214, the cultivation of arable land for corn and but with a more severe oxidation requirement. sugarcane instead of soybeans. Thailand’s biodiesel standard is also similar Rapeseed /Ca nola: to EN 14214. In addition, Taiwan and Hong Rapeseed and canola Kong are discussing standards similar to EN is essentially the same 14214. The Philippines’ standard is speci cally crop, but canola is a for B100 for CME (coconut methyl esters). version of rapeseed Biodiesel Feedstocks developed to lower the eruic acid to make A burning question today is how to supply the product safer for the feedstocks necessary to produce the human consumption. biodiesel mandated and/or subsidized by According to the USDA, in 2006, the EU governments internationally. One concern produced 15.41 mt of rapeseed, while the U.S is whether there is adequate arable land and and Canada produced approximately 0.7 water available to meet the growing demand. and 9.66 million mt of canola respectively. Additionally, there is a growing debate as to A large part of Canada’s canola crop is whether renewable fuels are being promoted exported to the U.S., and Europe is another at the expense of food. potential export market due to its current In most regions, the primary feedstock for rapeseed shortage. However, a problem for biodiesel is also used for human consumption, Canadian canola is the EU ban forbidding such as soybean oil in the U.S. and Brazil, the import of genetically modified crops. rapeseed and sun ower oil in Europe, palm oil This is currently under review by the EU in Asia and canola oil in Canada. One result due to its urgent need. of the food vs. fuel debate is that the increased Palm Oil: According demand for edible feedstocks tends to in ate to the March 2006 their price compared to non-edible feedstocks. Foreign Agricultural Feedstocks account for 80 percent of biodiesel Service (FAS) crop production costs and are the main reason that assessment, Indonesia biodiesel is more expensive than conventional and Malaysia together diesel fuel. According to the USDA, it takes accounted for over 85 about 7.3 pounds of soybean oil, which costs percent of global supply, about 30-35 cents per pound, to produce a each country producing gallon of biodiesel. Feedstock alone, therefore, approximately 15 million mt. Much of this accounts for approximately $2.45 per gallon is exported, especially to the EU. An of soy biodiesel. While fats and greases cost issue of serious environmental concern less and produce less expensive biodiesel, their is the practice of clearing tropical rain supply is more limited and localized. forests in order to make room for more Some of the common international biodiesel palm oil plantations. Both countries feedstocks are: have denied this practice and have Vegetable Oils: announced measures to protect the rain forests. However, recently, the European Soybeans: The U.S. is the Parliament has called for a ban on the world’s largest producer use of biodiesel processed from palm oil, of soybeans, producing stating that the growing production of almost 38 percent of palm oil, sugarcane and soy in southeast the world’s crop in Asia and South America is destroying 2006. According to the tropical forests and other ecosystems, USDA, in 2006 the U.S. resulting in huge carbon dioxide produced approximately emissions. They claim that carbon dioxide 7
    • released from clearing and draining peat or rain forests. If successfully cultivated, wetlands, and also forest fires in southeast this acreage would produce approximately Asia are related to the growing number of seven million gallons of biodiesel per year. plantations for biodiesel production. Jatropha is also being planted in a number of African countries and in Guatemala Coconut: The Philippines and the Philippines. However, it should is the rst nation to be noted that past attempts by the United domestically produce Nations to establish Jatropha plantations and use coconut-derived and associated industries have not proved biodiesel. In May economic or successful. 2007, the Philippine government introduced Animal Fats/Tallow: a biofuels act mandating Only the lower grades of inedible tallow are all oil rms to blend one candidates for the biodiesel pool since higher per cent (B1) coconut-methyl ester in their grades are absorbed by the chemical sector. diesel products. The Philippines’ Department Consequently, tallow is not a significant of Agriculture and the Philippine Coconut resource for U.S. biodiesel production. Authority (PCA) plan to develop 740,000 The lower grades have higher free fatty acres of land to meet the demand for expanded acid levels (FFA) and contain impurities, usage of coconut-methyl ester in diesel. making pre-processing a necessary step Jatropha Curcas (Physic Nut): Jatropha’s prior to transesterification. A major issue major advantage is that it can be grown in with tallow-based biodiesel is its very high virtually any tropical terrain and does not content of saturated fats, which translates compete with food crops for arable land, to a methyl ester with poor cold weather thereby avoiding any issues with the food vs. qualities. The cold flow pour point of fuel debate. However, unlike the byproducts tallow-based methyl esters can be as high of edible crops, the spent oil cake from as 59˚ F (15˚C), which is unacceptable even jatropha cannot be fed to animals or used in warmer climates. Tallow of sheep and in applications where its toxicity is an issue. cattle is the primary biodiesel feedstock in Jatropha is most popular in India, which Australia and is being considered for use in has identi ed almost 100 million acres of New Zealand. land that could potentially be dedicated to Yellow and Brown Greases: jatropha without impacting edible crops 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% er e rd t ed t n n t m d w er u fa u liv ea or ee ow al llo on La n w se er C ea O yb P es lo Ta oc n tt fl ff P to ap So n u C f Sa u B ee ot R S C B Saturated Fat Monounsaturated Fat Polyunsaturated Fat Biodiesel Feedstock Composition Impacts Performance 8
    • Other biodiesel feedstocks include the animal used. The differing levels of saturation determine fats and vegetable oils used for cooking. Used the properties of nished biodiesel. Biodiesel cooking oil is sometimes called “yellow” grease, made from feedstocks that contain highly and although there is no strict de nition, trap saturated fatty acids, (such as palm and coconut grease and sewage greases are referred to as oils, beef tallow and yellow grease), has a high “brown grease.” The de nitions of yellow and cetane number and superior oxidative stability. It brown grease are blurred and are often based on also helps reduce NOx emissions. One downside the degree of oxidation, color and FAA content. is that this biodiesel has poor cold weather Due to resource limitations, recycled cooking oil properties; it exhibits high cloud and pour points, alone is not a viable solution for the energy crisis. which means it tends to start forming crystals However, it is sometimes the feedstock of choice much too soon for use in colder climates. On the for small biodiesel plants. The biggest drawback other hand, biodiesel made from oils with high of these greases is their variable nature— they polyunsaturated content, (such as soy, canola and often contain deposits that must be ltered out, sun ower oils), has lower cloud and pour points, and have high FFA levels. They must undergo which make for better cold weather properties. a series of pre-treatment processes in order to However, it has a lower cetane number and poor meet the minimum quality requirements for oxidative stability, and also tends to produce transesteri cation. higher NOx emissions. It is possible to impact Feedstocks In uence Biodiesel Properties the varying properties of different biodiesel fuels by the use of additives. Biodiesel’s properties depend heavily on the speci c feedstock used, which is a challenge for Challenges of Biodiesel the industry since it is critical to ensure consistent High Cost – Biodiesel generally costs more to quality among the various blendstocks. Each manufacture than petroleum diesel, resulting animal fat or vegetable oil molecule used to in a wholesale price that is typically higher produce biodiesel via transesteri cation is by $1-$2 per gallon, according to the DOE. composed of a glycerine backbone of three Traditionally, B20 has been priced about 20 carbons, to each of which is attached a long chain cents more than diesel fuel while B2 has been fatty acid. These long chain fatty acids react with only a few cents more. The price difference methanol to make the methyl ester or biodiesel, is primarily due to high feedstock costs, and may be saturated, monounsaturated or and renders biodiesel uncompetitive with polyunsaturated, depending on the feedstock petroleum diesel. Currently the biodiesel Not all Engines Appreciate Biodiesel: Catastrophic Failure Caused by Biodiesel Use without Adjusting Maintenance Intervals and Using Compatible Lubricants 9
    • industry is reliant on a plethora of federal High Solvency Effect – Biodiesel has a and state programs, subsidies, production tendency to dissolve accumulated sediments in incentives and tax credits. For instance, diesel storage and engine fuel tanks, due to the federal blend tax credits of $1 and $0.50 per superior solvency properties of methyl esters. gallon exist in the U.S. for biodiesel produced These dissolved sediments can then plug fuel from agricultural and non-agricultural lters. Sometimes the lters burst, propelling feedstocks respectively. Similar tax credit sediment through the fuel injector system to schemes are used in other countries. Critics cause injector deposits and potential failure. argue that in order for biodiesel to be The solvency effect is much greater with high enduringly successful as a viable industry, it blends of biodiesel compared to B20 and lower must be economically self-supporting. blends. Therefore, before B100 is used for the rst time in tanks or lines previously used for Lower Energy Content – According to the petroleum diesel, it is important to clean the DOE, biodiesel (B100) contains approximately tanks and fuel systems thoroughly to remove 8.5 percent less energy per gallon than typical old sludge and deposits. It is also advisable to No.2 petroleum diesel fuel. This is due to check fuel lters frequently and change them the oxygen content in the ester molecules as necessary. of biodiesel, which essentially means that the molecule is already partially reacted Materials Compatibility – Pure biodiesel (combustion is the reaction between carbon degrades, softens or seeps through some hoses, and hydrogen with oxygen). Therefore, one gaskets, elastomers, seals, glues and plastics can think of biodiesel as partially burnt by with prolonged exposure, which can create about 12 percent. The difference in density fuel system leaks. Nitrile rubber compounds, between FAME and mineral diesel then results polypropylene, polyvinyl and Tygon materials in the per gallon difference in energy content are especially susceptible. Using biodiesel of approximately 8.5 percent as stated above. blends higher than B20 can damage fuel One gallon of No. 2 diesel contains 129,050 systems components such as hoses and pump BTUs, while one gallon of biodiesel contains seals, which contain elastomers incompatible 118,170 BTUs. While this difference in energy with biodiesel. In this situation, users should content is often imperceptible with respect to consider replacement with compatible power, torque and fuel economy in engines elastomers. However, this is primarily an issue using blends up to B20, it can de nitely be with older engines manufactured before 1993, noticeable with B100. Since fuel accounts for according to the DOE. The recent switch to up to 50 percent of a truck eet’s cost, small ULSD has meant most OEMs have converted differences in cost and energy content (fuel to components that are also suitable for use economy) can result in a signi cant impact on with biodiesel. B5 and lower blends have not truck eet pro tability. exhibited elastomer deterioration and may not require modi cations. Poor Cold Weather Performance – Biodiesel freezes or gels up in cold weather sooner than B20 and higher biodiesel blends will degrade petroleum diesel, due to its relatively high and create sediments after prolonged contact pour point temperature. As the fuel gels, it with bronze, brass, tin, copper, zinc and lead. becomes increasingly viscous, clogging fuel Copper pipes and ttings, brass regulators, lters and hindering the passage of fuel zinc linings and lead solders should also be from the tank to the engine. Cold weather avoided. Biodiesel is hydroscopic, meaning it properties are the major reason that many attracts moisture. Once it comes in contact people use biodiesel blends as opposed to neat with moisture, it can hydrolyze and form biodiesel, B100. The NBB recommends that a variety of organic acids which are partly the same cold weather performance solutions, responsible for its compatibility problems (kerosene and cold ow additives), that are with various seal, elastomers, and metals. utilized with No.2 diesel fuel, should also Low Oxidative Stability – Biodiesel has lower be used with B20. While B20 usually raises oxidative (long-term storage) stability than fuel cold weather properties such as cloud petroleum diesel. Factors affecting biodiesel’s point, pour point and lter plugging point by oxidative stability include the degree of 2-10˚F, B5 and B2 have virtually no impact saturation of the feedstock, the level of natural on cold ow. Biodiesel’s cold ow properties antioxidant content, carbon chain length and are heavily dependant on feedstock selection, the presence of glycerides. In biodiesel, fuel as described earlier in this article. aging and oxidation can create high viscosity, 10
    • high acid numbers and the formation of lter- product quality. Therefore, the spotlight is clogging varnish and sediments. The NBB shifting to what is called second generation recommends a six-month maximum storage life and third generation, or renewable diesel, for B100. If the fuel is kept longer, antioxidants which has the potential to cover a greater should be added and periodic tests should be portion of world energy demand. Unlike performed to ensure the fuel continues to meet biodiesel, second generation renewable diesel the ASTM D 6751 speci cation. Suitable storage is manufactured in oil re neries using a tank materials are steel, aluminum, uorinated chemical process similar to the conversion of polyethylene, uorinated propylene and crude oil into motor fuel. Third generation Te on. Some suppliers use nitrogen blanketed renewable diesel can be obtained from ligno- storage vessels to reduce the tendency of stored cellulosic sources such as straw, timber, biodiesel to oxidize and to help keep moisture woodchips, plant waste or manure. Since and condensation out of the tank. the technology allows renewable diesel to be produced from any plant material, this Increased NOx Emissions – Biodiesel causes would eliminate the competition between a slight increase in emissions of ozone- food and fuel as well as the nished product forming nitrogen oxides (NOx), according quality concerns that are intrinsic to rst to the DOE. The precise composition of generation biodiesel production. The main biodiesel in uences NOx emissions. There source of raw materials for energy would is around 15 percent NOx variability among shift from arable land to forests, peat bogs, the various biodiesels meeting ASTM D 6751, and crop and municipal residue. The process with soybean oil-derived biodiesel creating is called biomass-to-liquid (BTL), in which the highest increase in NOx due possibly the previously pelletized biomass is directly to reactions with its high polyunsaturated gasi ed at low pressure. The resulting fatty acid content. Although biodiesel itself synthetic gas is puri ed and then converted contains very little bound nitrogen, NOx is into a liquid diesel fuel using a catalytic created in the engine as nitrogen and oxygen conversion process like the Fischer Tropsch in the intake air react at the high in-cylinder synthesis reaction. Unlike rst generation combustion temperatures. Some effort is biodiesel, the properties of the nished being made to solve this problem with the use second or third generation renewable diesel of exhaust after-treatment systems in newer product are independent of the feedstock. engines, but the possible increase in the NOx levels when biodiesel is used in older engines While rst and second generation biodiesel is a concern. There are research efforts is mainly produced from grain kernels only, underway by the California Air Resources third generation biodiesel is manufactured Board (CARB) and by the EPA to de ne the from the entire plant, offering the prospect problem of NOx increase more precisely. of much higher yields. Plus, a signi cant Some past work has indicated the increased environmental advantage of third generation NOx is related to differences in injection biodiesel is its lower greenhouse gas emissions. rates into the combustion chamber caused It has a smaller carbon footprint since the by biodiesel’s higher viscosity and bulk amount of energy-intensive fertilizers and modulus, which makes it less compressible fungicides remains unchanged for a far than petroleum diesel. The higher bulk greater output of useable material. modulus and higher speed of sound of There are two sizeable obstacles that need to biodiesel means the pressure rises in the be overcome before third generation biodiesel fuel lines and develops an advance of nearly arrives at the pumps—technology and two degrees in injection timing. This in turn cost. The BTL production process is much generates a faster pressure and temperature more complicated than transesteri cation. rise in the combustion cylinder, leading to an Relatively high manufacturing expenditure increase in NOx. means that third-generation biodiesel cannot yet be produced economically on a large scale. Second Generation Biodiesel and Biomass- However, ultimately it offers higher potential to-Liquid (BTL) or “Renewable Diesel” for production and cost reductions, because Today’s FAMEs are considered rst it can be sourced from biowaste with fewer generation biodiesel. In spite of enormous competing end-uses. Consequently more investment efforts, this biodiesel alone is not research projects are being launched worldwide suf cient to ful ll growing global energy for the purpose of developing biomass-based demand and there are concerns regarding processes to commercial maturity. 11
    • Two second-generation renewable diesel ConocoPhillips and Tyson Foods Unite to projects are highlighted below: Produce Second Generation Biodiesel Neste Oil’s NExBTL ® Technology In April 2007, meat producer Tyson Foods and oil company ConocoPhillips announced Finland’s Neste Oil has developed NExBTL , ® plans to work together to produce second which stands for NExt generation Biomass To generation renewable diesel fuel from pork Liquids diesel technology, and incorporates and poultry fat. Using a proprietary thermal a unique approach of combining natural depolymerization production technology, renewable raw materials with traditional oil the animal fats will be processed and then re ning processes. It is similar to “H-Bio,” fed along with hydrocarbon feedstocks to a the second generation biodiesel developed hydrotreater unit, to produce a high-quality by Italy’s ENI and Brazil’s Petrobras. The diesel fuel that meets all federal standards process consists of hydrogenating fatty acids for ultra-low-sulfur diesel. The nal product across a nickel-molybdenum catalyst under has a high cetane value, and the processing high pressure. It can use multiple plant oil step improves storage stability and handling feedstocks and animal fats to create a superior characteristics compared to biodiesel created product with characteristics similar to ultra- by transesteri cation. The bene t of treating clean synthetic biodiesel. The advantage of the animal fats this way is that the nished NExBTL® and the similar H-Bio technology product could be passed through multi- is that it can be fully integrated in existing product pipelines just as ultra-low-sulfur oil re neries, and the nished fuel properties diesel is today. are largely independent of the feedstock. Such re neries already have hydrogenation The two companies estimate that the facilities, therefore renewable diesel units operation could result in 175 million gallons can be more easily incorporated into existing of renewable diesel a year. As previously plants. The rst NExBTL® plant started mentioned, animal fats and cooking greases production this year in Porvoo, Finland, with alone cannot solve the energy crisis. To put a capacity of 170,000 tons a year. things in perspective, the U.S. consumed approximately 62 billion gallons of diesel NExBTL® is sulfur-, oxygen-, nitrogen-, and in 2006, according to the DOE. Thus, aromatic-free and has a very high cetane ConocoPhillips and Tyson’s contribution number. It can have acceptable cold weather would constitute less than one percent of the properties, good storage stability, low water overall diesel consumption. solubility and also reduces exhaust emissions. However, the distillation curve is different The companies are expecting to be able from that of mineral diesel and the lack of to take advantage of the $1 per gallon tax light ends has some Original Equipment credit that will make the fuel cost effective. Manufacturers (OEMs) concerned about cold Although the tax credit is set to expire in start problems if B100 were to be used in cold 2008, it is likely to be extended given the climates. NExBTL® biodiesel is compatible government’s commitment to ensuring that with the existing diesel eet as well as with biodiesel stays competitive with regular fossil diesel logistics systems, and is technically fuel diesel. easy to blend in conventional diesels in all National Biodiesel Accreditation Program: ratios. The EU has approved NExBTL® as a BQ-9000 certi ed EU diesel fuel. Biodiesel fuel quality is of paramount concern Neste has labeled NExBTL® as “renewable” and importance to the biodiesel industry. diesel to distinguish it from traditional For this reason, the NBB has established a biodiesel, a distinction that may prohibit quality assurance program called BQ-9000 the fuel from enjoying some incentives and for the accreditation of biodiesel producers mandates designated speci cally for mono and marketers. The primary objective alkyl ester biodiesel. This issue is currently of BQ-9000 is to ensure that biodiesel is being discussed in the U.S., where the $1 per consistently manufactured per the ASTM gallon tax credit for biodiesel would apply D 6751 standard. BQ-9000 combines the for NExBTL® today, based on an Internal ASTM standards with an integrated quality Revenue Service ruling that was issued in program that includes storage, sampling, April 2007. The NBB, amongst others, is testing, blending, shipping, distribution challenging the ruling. and fuel management practices. To receive 12
    • accreditation, companies must pass a rigorous B100) will not void their parts and review and inspection of their quality control workmanship warranties, provided the processes by an independent auditor. There biodiesel meets ASTM D 6751. Some are two types of accreditation; Accredited OEMs also recommend that biodiesel be Producer and Certi ed Marketer. purchased solely from BQ-9000 certified A national fuel quality testing project, co- companies. Certain OEMs even fuel funded by NBB and the NREL, discovered their new diesel vehicles with biodiesel that 59 percent of biodiesel samples taken blends in the factory, such as John Deere between November 2005 and July 2006 with B2 and Case IH with B5. Chrysler were out of speci cation for incomplete also fills all its diesel-powered Jeep ® processing, containing trace quantities of Libertys, Dodge Rams and Jeep Grand un-reacted di- and tri- glycerides. These un- Cherokees with B5. Furthermore, the reacted components will also combine with Energy Policy Act (EPAct) encourages natural sterols in biodiesel, leading to large municipalities and non-combat military molecules that will not pass through lters. vehicles to use B20 by allowing fleets This is the same issue that caused some lter to meet part of their alternative fueled clogging problems in Minnesota in winter, vehicle (AFV) acquisition target through since cold weather can amplify problems purchase credits awarded for the use of caused by out-of-speci cation fuel. The B20 or higher blends. This has compelled NBB/NREL test results indicate that some some OEMs to warrant B20 use in these producers are not correctly monitoring applications. For instance, Chrysler has the quality of their biodiesel, and help to approved B20 use in its Dodge Ram underline the importance of BQ-9000. pickup trucks for government, military and some commercial fleet customers. Germany and Austria have established a similar program called the “Arbeitsgemeinschaft The NBB, together with major OEMs, has Qualitätsmanagement Biodiesel” (AGQM) formed the B20 Fleet Evaluation Team (B20 or the “Labor Group for Biodiesel Quality FET) to develop a position on the use of Management.” This organization includes biodiesel blends up to B20 in diesel engine many service stations that offer biodiesel, applications in the U.S. The B20 FET which have pledged to sell only rape methyl has identified a list of recommendations ester (RME) since it is the sole form of biodiesel for users dated June 2005 and titled, approved by certain original equipment “Technical Recommendations for B20 manufacturers (OEM). Fleet Use Based on Existing Data.” This also applies to blends over B5 and below Original Equipment Manufacturers B20, such as B11, which is popular in (OEMs) and Biodiesel Illinois. While this list is not intended to All engine and vehicle OEMs provide a replace warranty limitations established material and workmanship warranty on by individual OEMs, it is a statement of their products. These warranties do not confidence that B20 can be used trouble cover problems caused by external factors free if appropriate precautions are taken. out of their control, such as fuel variations. Simultaneously, the NBB is also actively Therefore, the most important points working with the ASTM to develop a regarding engine warranties and biodiesel separate standard for B20. This will be are whether an OEM will void its warranty critical in enabling OEMs to increase when biodiesel is used, and whether the fuel their recommended biodiesel blend level supplier will stand behind its fuels in case to B20. As previously mentioned in the of trouble. Existing and potential users of section on standards, the EMA has issued biodiesel should consult with their OEM a B20 “Test Specification for Biodiesel representatives to determine what the terms Fuel,” and work is also ongoing to create and conditions of their warranty coverage distinct specifications for blends up to might be. Local laws and regulations vary B5, and between B6 and B20. in this respect. Position of International OEMs Position of U.S. OEMs In Europe, since the EN 590 standard permits All major OEMs have stated formally diesel fuel to contain up to B5 without being that the use of biodiesel blends up to labeled, in practice, the user has no idea B5 (and in some cases B20 and even which blend is actually lled at the pump. 13
    • As a result, most major heavy-duty and OEM Concerns with Biodiesel passenger car European OEMs have been OEMs are worried about biodiesel’s impact compelled to accept B5. They will honor on three key engine components - fuel system, their warranties with the use of biodiesel lubricant performance and emissions system. blends up to B5, provided the biodiesel meets EN 14214. Currently, the EU is investigating While B5 is generally considered safe, users of the possibility of allowing up to B10 in the higher concentrations of biodiesel have reported EN 590 standard in 2008. fuel system problems such as corrosion and deposits in injection systems and compatibility The Japanese heavy-duty OEMs allow the use issues with rubber seals in fuel systems. While of up to B5 in their engines, provided the neat biodiesel’s effect on engine lubrication is not biodiesel meets JASO M360, the Japanese completely understood, one de nite fact is that speci cation introduced in April 2007. It is its higher density, surface tension, and viscosity similar to EN 14214, but incorporates more relative to mineral diesel creates fuel dilution severe oxidation requirements. in the crankcase and engine corrosion issues Below is a table that lists some of the OEMs’ plus sludge and piston deposits. Most OEMs current positions on warranties with the use will honor their warranties in the case of these of biodiesel blends. Since these often change, higher blends more or less on a case-by-case the end user is strongly advised to consult basis, and only if their recommendations are the speci c OEM before utilizing any level of implemented. However, major diesel injection biodiesel blend. manufacturers Denso, Delphi, Siemens VDO Manufacturer Warranty Position Case IH All engines approved for up to B5 and most for up to B20. Must meet ASTM D 6751 or EN 14214 Caterpillar Many engines approved for B30 and B100, others limited to B5. Must meet ASTM D 6751 or EN 14214 Cummins Most post-2002 engines approved for up to B20, must meet ASTM D 6751 Daimler/Chrysler All engines approved for up to B5 and some for up to B20. Must meet ASTM D 6751 Detroit Diesel Approve up to B5, must meet ASTM D 6751 Ford Up to B5, must meet ASTM D 6751 or EN 14214 General Motors All engines approved for up to B5 and some up to B20. Must meet ASTM D 6751 International Approve up to B20, must meet ASTM D 6751 John Deere All engines approved for up to B5, must meet ASTM D 6751 or EN 14214 Mack Up to B5, must meet ASTM D 6751 Mercedes-Benz Up to B5, must meet ASTM D 6751 plus have the necessary oxidation stability (min. 6h, proved with EN14112 method) to prevent damage from deposits and/or corrosion New Holland Up to B20, must meet ASTM D 6751 Scania Up to B5 and also B100 with reduced drain intervals. Must meet EN 14214 UD Trucks/Nissan Diesel Up to B5, must meet EN 14214 or ASTM D 6751 Volkswagon Up to B5, must meet EN 14214 or ASTM D 6751 Volvo Up to B5, must meet EN 14214 or ASTM D 6751 Fuel Injection Equipment Manufacturer Bosch Up to B5, must meet EN 14214 Delphi Up to B5, must meet ASTM D 6751 Siemens VDO Up to B5, must meet EN 14214 or ASTM D 6751 Stanadyne Up to B20, must meet ASTM D 6751 Denso Up to B5, must meet EN14214, ASTM D 6751, or JASO M360 depending on region 14
    • and Bosch will not honor their warranties with In order to address some of these issues, most the use of biodiesel blends above B5. Stanadyne, European OEMs prescribe a 50-70 percent on the other hand, will warrant up to B20. reduction in oil drain intervals with the use of biodiesel blends above B5. For instance, in the The increasingly strict emissions regulations case of Mercedes Benz trucks, this means service oblige the OEMs to use extremely precise intervals decrease from 100,000 km to 30,000 equipment, as well as guarantee in-use km, a 70 percent reduction. Unfortunately, emissions compliance for an extended for large eets, these reduced service intervals duration (for example, 10 years or 485,000 are scally unattractive, and act as a deterrent miles for heavy-duty trucks in the U.S.) to the use of biodiesel blends above B5. This, Biodiesel poses an unknown factor in this along with biodiesel becoming more expensive equation – it has not been the subject of any as subsidies expire, has led to a drop in usage certi cation work, and its impact on emissions of biodiesel in some countries. For instance, and emissions system durability is not yet the German government is reducing some of its fully known. Moreover, various biodiesel many subsidies and tax incentives for biodiesel, blends may potentially impact emissions effectively eliminating the nancial advantage. in different ways. Many believe the OEMs should not be responsible for differences in Pure Plant Oils emissions levels due to biodiesel use. Some German eet operators have replaced While the use of B5 is generally trouble-free B100 with pure plant oils, which do not meet in the case of older diesel passenger cars and EN 14214. These oils have created numerous heavy-duty trucks without diesel particulate issues for OEMs and operators, including lters (DPFs), increasing problems have cold-start dif culties, corrosion and elastomer been detected in newer engines with DPFs. degradation. A similar situation also arose in In some applications, OEMs are using a late Brazil, where some eets were motivated by “post” injection to help regenerate DPFs. price to mix vegetable oil directly with diesel, This late injection may create higher levels resulting in engine failures. It is for this reason of fuel dilution. Biodiesel is more persistent that biodiesel is strictly de ned as a mono alkyl once it enters the crankcase and thermally methyl ester (same as a fatty acid methyl ester). decomposes forming insolubles and deposits. Pure plant oils generally have high viscosities OEMs have noted situations where fuel and contain substances that will form gums dilution rates ran up to 15 percent in vehicles and deposits in fuel systems, and as such are not operated with DPF and post injection. acceptable for use in modern diesel engines. Fuel System Emissions Systems Injector deposits Impact on after- Fuel filter plugging treatment devices and sensors Injection pump durability Impact on NOx Materials incompatibility emissions Fuel Instability Lower BTU Low temperature handling content/fuel economy May reduce detergency and anti-foam properties of fuel additive Lubricant Performance packages Fuel dilution Corrosion Viscosity increase Oxidation Piston Deposits Sludge Deposits Wear OEM Biodiesel Concerns and Unknowns 15
    • Diesel – normal droplet size Larger fuel spray droplet size Late or post injection leads to higher levels of fuel dilution Crankcase Fuel Dilution with Biodiesel-Properties of Biodiesel Lead to Higher Fuel Dilution Levels than Mineral Diesel Part I-Summary of the concerns and issues being faced by the industry. In Part II, we will focus on In this rst part of a two-issue series, the diesel engine oil lubrication performance reader has gained a basic understanding of when biodiesel is used. Bench tests as well as the nature of biodiesel, current and future laboratory engine test data will be presented. biodiesel production techniques, and some Higher and Narrower boiling range of biodiesel makes it more persistent once it enters the crankcase 400 Narrow Boiling Range of 350 Biodiesel Temperature, °C 300 250 R M E B io d ie s e l 200 M in e r a l 150 100 50 0 10% 50% 90% Percent of Fuel Evaporated Crankcase Fuel Dilution with Biodiesel-Higher and Narrower Biodiesel Boiling Range Makes it More Persistent Once Inside the Crankcase 16
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