Use of Biodiesel in a Transit Fleet (2007)

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OVERVIEW This chapter provides a general overview of renewable en- ergy products collectively known as biomass and the fuels made from it, with a focus on biodiesel. BIOMASS Biomass is broadly defined as any organic material made from plants or animals. Examples include agricultural and forestry residues, municipal wastes, industrial wastes, and animal residues. In addition to “recycled” organic waste products, biomass has come to include crops grown exclu- sively for energy use. Although animal products play a role, the majority of biomass feedstocks come from plant-derived material—essentially all energy originally captured by pho- tosynthesis. Photosynthesis is the process by which green plants use sunlight to synthesize carbohydrates from carbon dioxide (CO2) and water. Because it comes primarily from plants and animals bio- mass is renewable, unlike the fossil fuels that provide the vast majority of our current energy needs. Fossil fuels supply ap- proximately 86% of the energy consumed in the United States, with the majority coming from foreign markets. Even more disturbing is that our dependency on foreign energy continues to grow. Because the U.S. economy is so closely tied with petroleum products and oil imports, small changes in oil prices or disruptions in supply can seriously affect our economy. As a renewable energy source that can be produced do- mestically, biomass offers an alternative to conventional energy to help provide national energy security, economic growth, and environmental benefits (1). To assist with achieving these goals, the DOE is supporting the creation of a new bio-industry that expands the use of biomass as a sup- plement to fossil fuel-based petroleum (1). As of 2000, biomass surpassed hydroelectric power to become the largest U.S. renewable energy source, supplying more than 3% of our nation’s total energy consumption. Most of this energy is in the form of industrial heat and steam used by the pulp and paper industry. BIOFUELS Biofuels are produced from biomass and represent the only renewable alternative liquid fuel for transportation, a sector that 4 strongly relies on imported oil. In most applications a percent- age of biofuel is blended with traditional fuels. In other cases biofuel can be used as a direct, 100% replacement for fuels such as gasoline and diesel; however, this is the exception rather than the norm for several reasons. One is that original equipment manufacturers (OEMs) typically restrict the percentages of bio- fuels allowed in their engines for warranty purposes. Another is that certain biofuels, especially biodiesel, have characteristics that when used in higher concentrations present challenges that must be addressed to ensure successful implementation. Because of this, those considering the use of biofuels are strongly advised to learn more about the characteristics of these fuels and to consult engine OEMs for their position. In addition to biodiesel, examples of other biofuels include ethanol, E-diesel, and dimethyl ether. Ethanol, also known as ethyl alcohol or grain alcohol, is currently the most widely used biofuel and lends itself as a supplement to gasoline. E-diesel is a mixture of ethanol and diesel along with addi- tives that prevent the two fuels from separating at very low temperatures. Dimethyl ether, also called methyl ether and wood ether, is a colorless gas that can be made from natural gas, coal, or biomass as a clean-burning alternative to diesel, gasoline, and other fuels. BIODIESEL Overview Biodiesel is another biofuel and the subject of this report. As with the others, it is renewable and sourced domestically. Europe is the largest producer and user of biodiesel, which uses rapeseed (canola) oil as the primary feedstock. In the United States, the second largest producer and user, biodiesel is typically made from soybean oil, other agricultural products, or recycled restaurant grease. Although biodiesel contains no petroleum, it can be blended at any level with petroleum diesel. As with other biofuels, biodiesel is expressed as the per- centage of the product contained in the fuel. For example, 100% biodiesel containing no petroleum diesel is expressed as B100, and is also known as pure or “neat” biodiesel. One pop- ular blend for vehicle applications contains 20% biodiesel and 80% petroleum diesel, and is expressed as B20. Other per- centages of biodiesel are referred to as B5, B80, and so forth. Methanol, which had been used with mixed results as a motor fuel for transit buses in the 1980s and 1990s, plays a CHAPTER TWO UNDERSTANDING BIODIESEL—THE BASICS

5critical role in the production of biodiesel. Also known as wood alcohol or methyl alcohol, methanol is primarily made from natural gas. In the manufacturing of biodiesel, oils from the feedstock (soy, canola, etc.) are reacted with methanol to produce methyl esters (the official term for what we call biodiesel) and glycerin (2). For every 100 lb of biodiesel produced, approximately 10 to 15 lb of glycerin is also generated. Glycerin is an ingredient typically found in hand lotions and soaps. It is also being tested as an alternative feedstock for producing antifreeze (propylene glycol), which may help offset some of the costs associated with producing biodiesel (3). The oils used in biodiesel are natural products and their composition and properties will vary according to their origin. Because of this, readers should note that any natural oil prod- ucts that have not been formally processed into biodiesel should not be used in diesel engines. This especially holds true for raw or refined vegetable oil or recycled greases. Research shows that vegetable oil or greases used in these engines at lev- els as low as 10% to 20% can cause long-term engine deposits, ring sticking, lube oil gelling, and other maintenance problems that can reduce engine life (4). Before it can be used in diesel engines, biodiesel must conform to a specification developed by ASTM known as ASTM D6751. Use of this ASTM speci- fication is critical to ensure that biodiesel provides optimal fuel performance. Additional information on this important speci- fication is provided in chapter three. As with ethanol, the production of biodiesel has increased sharply over the past several years. In 2002, 15 million gallons of biodiesel were consumed in the United States. By 2005, production had increased to 75 million gallons and in 2006 production tripled to approximately 225 million gallons (5). Advantages Biodiesel’s many advantages are summarized here and will be expanded on in subsequent chapters. Reduced Foreign Oil Dependency As presented earlier, biodiesel’s primary advantage is as a do- mestic and renewable energy source that can help reduce our dependency on foreign oil. According to the Energy Informa- tion Administration, the United States spends approximately $250 billion annually on foreign oil, which translates to approximately $475,000 per minute (6). The U.S. consumes approximately 20 million barrels of oil per day; by 2025, the demand is expected to rise to 26 million barrels a day, of which 60% is projected to be imported. Given our growing dependency on foreign oil, increasing demands from other parts of the world, and the instability in the Middle East where much foreign oil is sourced, biodiesel and other domestically made fuels can play an important role in strengthening our nation’s energy security. To put it in per- spective, if just 5% biodiesel were added to the 37 billion gallons of on-road diesel used in the United States annually it would displace 1.85 billion gallons of petroleum diesel (6). Positive Energy Balance Many alternative fuels require more energy to produce than the fuel itself provides. This is not the case with biodiesel. Although estimates vary, even under a worst-case scenario, biodiesel made from soybeans is a net energy generator (7). Using the national average, for every one BTU (British ther- mal unit) of energy used in the production of soybean-based biodiesel, an average of 2.5 BTUs of energy output is realized (a 151% energy gain). When the best agriculture and oil pro- cessing practices in the United States are used, 3.24 units of energy are produced, yielding a 224% energy gain. According to the National Biodiesel Board (NBB), this represents the highest energy balance of any fuel. The calculations, which are based on a so-called “well-to-wheel” analysis, take into ac- count all of the energy consumed during the production of biodiesel, including energy used for transportation, production of fertilizers and pesticides to grow the feedstocks, fuels used to produce steam and electricity, and the methanol used in the manufacturing process. Proponents of biodiesel point to the positive energy balance as a major factor in ensuring its longevity as a viable fuel option. Simplicity Biodiesel blends are simple to use in that they require no spe- cial handling considerations. Unlike other alternative fuels that can require substantial infrastructure investments, biodiesel blends of B20 and lower can be used in compression-ignition (diesel) engines with little or no vehicle or facility modifica- tions. Blends over B20, however, typically require additional considerations. Biodiesel is biodegradable and essentially free of sulfur and aromatics. A sample Material Safety Data Sheet (MSDS) provided by the NBB indicates that the potential heath effects of biodiesel are minimal (5). In essence, handling considera- tions are essentially the same as petroleum diesel fuel and carry similar risks. A sample MSDS for B100 is included as Appendix A. Biodiesel users should, however, obtain an MSDS from their fuel supplier to ensure it is appropriate to the specific fuel delivered. Lower Emissions According to the EPA report, A Comprehensive Analysis of Biodiesel Impacts on Exhaust Emissions, B20 reduces total unburned hydrocarbons (HC) by 20% and carbon monoxide (CO) and particulate matter (PM) by 12% each (8). Use of biodiesel can also help meet national goals for the net reduc- tion of atmospheric carbon. A study by the DOE found that

biodiesel production and use, in comparison with petroleum diesel, produces 78.5% less carbon dioxide (CO2) emissions because crops such as soybeans used to make biodiesel actu- ally consume CO2 during the growing process (9). The same study, however, suggests that net CO2 reduction may be lower owing to other factors. The effect of biodiesel on nitrogen oxide (NOx) emis- sions, however, has created a controversy in that some test- ing has shown a slight increase in emissions, others a slight decrease, whereas one study shows no effect at all. The variability in testing results using a variety of duty cycles combined with the lack of testing on engines equipped with diesel particulate filters (DPF) and NOx emissions controls indicates that additional research is required regarding biodiesel and NOx emissions. Aside from the NOx controversy, biodiesel’s ability to lower emissions stems from the fact it contains 11% oxygen by weight, which provides more complete combustion of fuel in the engine. Detailed information on biodiesel exhaust emissions is contained in chapter three. Added Lubricity With the introduction of ultra-low sulfur diesel (ULSD) to meet 2007 EPA emissions regulations, the removal of sulfur has also reduced fuel lubricity. Lubricants are needed in diesel fuels to keep the engine’s moving parts such as the fuel pump from wearing out prematurely. Fuel suppliers com- pensate for the lack of lubricity by including fuel additives to their ULSD fuels to meet ASTM standards. However, for those agencies seeking lubricity levels higher than the mini- mal requirements, use of biodiesel as low as B2 can enhance lubricity to the point where additional lubricity-enhancing additives (some of which may be toxic) are not required. Higher Cetane B100 that meets ASTM D6751 specifications typically has a cetane number (a measure of the combustion quality of diesel fuel during compression ignition) higher than 47, which compares with a cetane average of 43 for highway diesel fuel. Biodiesel’s higher cetane number provides for easier engine starting and quieter engine operation. Incentives The use of biodiesel offers incentives at federal and state levels. On the federal level, biodiesel is considered an alterna- tive fuel under the Energy Policy Act (EPAct), which through various amendments made since 1992, allows some vehicles operating on biodiesel to qualify for certain credits and bene- fits (9). EPAct was passed by Congress to reduce our depen- dency on foreign oil by requiring certain federal, state, and 6 public utility fleets to acquire alternative fuel vehicles (AFVs) capable of operating on non-petroleum fuels. Provisions contained in EPAct allow some agencies to meet their AFV purchase requirements by using specified amounts of biodiesel. Individual states also offer credits and other incen- tives for biodiesel use. Additional information on biodiesel in- centives is provided in chapter three. Flexibility The nature of biodiesel is such that depending on pricing and availability of diesel or biodiesel, agencies can increase or decrease their use of the fuel without having to make signif- icant changes to the fleet or fueling infrastructure. In addi- tion, for agencies operating diesel–electric hybrid buses or diesel-powered support cars and trucks biodiesel can be used in those vehicles as well. Potential Downsides Despite its many advantages, there are potential disadvan- tages associated with biodiesel that must be understood. Many of the drawbacks apply to B100 and may not be of consequence with lower blends such as B5, B10, and B20. Understanding the full range of potential downsides associ- ated with B100 will help with the implementation of lesser concentrations. Once understood, the good news is that the drawbacks can be greatly minimized or even eliminated. Chapters four and five will provide actual agency experi- ences with various biodiesel blends and the steps being taken to make the fuel work for them. It is important to note that any biodiesel blend is only as good as the base diesel from which it is blended. Many prob- lems attributed to biodiesel are the result of poor quality diesel fuel; sometimes the distinction is difficult to make. Lower Energy Content The energy content of diesel fuel, expressed in BTUs, is a determining factor in fuel economy and the engine’s ability to make power. The energy content of conventional diesel can vary up to 15% depending on the supplier and time of year, with No. 2 diesel fuel typically having higher energy content than No. 1 diesel fuel. When compared with most No. 2 diesel, B100 has slightly lower energy content. Whereas No. 2 diesel has approxi- mately 129,000 BTUs per gallon, B100 has approximately 118,000 BTUs, which amounts to about an 8% reduction per gallon. Although the difference is more pronounced with B100, a typical B20 blend of biodiesel will reduce power, torque, and fuel economy only about 2%, which in practice may be difficult to detect from day-to-day operations, even in closely monitored fleets (5).

7Cleansing Action Because B100 is a solvent it may dislodge sediments contained in diesel storage tanks, dispensing lines, and onboard vehicle fuel delivery systems. As a result of this cleansing characteristic, diesel fuel storage tanks may need to be cleaned in advance of introducing biodiesel and/or fuel filters checked more frequently to prevent them from plugging. Cold Weather Operation B100 begins to thicken or “gel” at higher temperatures than diesel, which must be considered by those operating in colder climates. The extent to which lesser blends of biodiesel begin to gel depends on the temperature, the quality of the base diesel fuel, the type of base diesel fuel (No. 1 vs. No. 2), the region where biodiesel is sold, and other factors. Gelling of any diesel-based fuel impedes its ability to travel through lines and filters, which in turn creates problems with facility and vehicle fuel delivery systems. Because this subject is of significant concern it is addressed in more detail in chapter three. Chapters four and five will discuss steps that some agencies take in winter, such as using fuel additives and changing to lighter biodiesel blends (e.g., from B20 to B5), to avoid potential cold weather problems. Material Incompatibility Biodiesel incompatibility with certain materials is another potential concern, which again strongly depends on the con- centration of biodiesel used. B100 has a much greater effect, biodiesel blends of 20% or less a much lesser effect, whereas the effects are said to be virtually nonexistent with low-level blends such as B2. The types of materials affected by biodiesel and the methods to mitigate the effects are discussed in chapter three. Fuel Blending Options Biodiesel can be blended with any type of diesel fuel includ- ing kerosene, No. 1 diesel, and No. 2 diesel. Biodiesel can also be blended with heating oil used in home furnaces. As long as biodiesel is thoroughly blended with diesel fuel it generally remains together as a cohesive fuel over time. As will be noted in chapter three, however, temperatures at or below the freezing point of any diesel fuel will cause fuel delivery problems. However, without exception, biodiesel cannot be blended with gasoline. Blending typically consists of mixing pure biodiesel (B100) with a petroleum diesel stock. How and where the two fuels are blended will affect the thoroughness of the mixing. The easiest way is to purchase fuel from a supplier that has premixed biodiesel into a finished product that meets all specification and quality requirements defined by the customer. The newness of biodiesel in certain areas, however, may make it difficult to obtain premixed blends to exact agency requirements. With time, preblended biodiesel should become more common. There are three general methods for blending biodiesel with diesel: splash blending, in-tank blending, and in-line blending. With splash blending, B100 biodiesel is typically poured atop the existing diesel fuel. Mixing occurs naturally as the heavier B100 works its way downward through the diesel fuel within the storage tank, although the mixing may not be as thorough. In-tank blending is much like splash blending; the two terms are often used interchangeably. However, in-tank blend- ing includes some form of mechanical agitation to assist with the mixing process. In one example, B100 is poured or “splashed” into a tanker truck that already contains diesel fuel. The blending that takes place during transportation as the truck travels across various road surfaces is generally sufficient. Short trips and/or colder temperatures, however, can prevent the two fuels from becoming thoroughly mixed. In another example, diesel and B100 are poured into a tanker truck or agency storage tank one right after the other at high enough fill rates to provide in-tank mixing. Some tanker tucks and fuel storage tanks are also equipped with mechanical recirculation systems to ensure more thorough in-tank blending. In-line blending is the most effective and involves adding biodiesel to the diesel as it flows through the distribution pipe. Additives are typically blended with fuels using this method. A form of in-line blending can also take place at an agency’s facility if the tanker truck can carry B100 and diesel in separate containers and deliver the fuels simultaneously through a common “Y” connector. Additional information on biodiesel blending is provided in chapter three. Locating Biodiesel Suppliers Given the relative newness of biodiesel, finding a biodiesel distributor or retail outlet may be difficult in certain parts of the country. Owing to the number of biodiesel outlets and the frequent additions that occur, it would not be practical to list them all here. For a complete and current listing of biodiesel suppliers, distributors, and retail sites, readers can contact NBB at 800-841-5849 or at http://www.biodiesel.org.