BIODIESEL FAQ Tim Stombaugh, Czarena Crofcheck, Mike Montross, Biosystems and Agricultural Engineering
AEN-90
BIODIESEL FAQ Tim Stombaugh, Czarena Crofcheck, Mike Montross, Biosystems and Agricultural Engineering
Biodiesel and other alternative fuels continue to gain popularity as petroleum fuel prices rise and we become more concerned about our environment. Introduction of these fuels raises many questions about actually using them in current equipment. The purpose of this factsheet is to address some of the common questions asked by those considering the use of biodiesel in existing diesel equipment.
What is biodiesel? performance. In most applications, if the remove deposits and buildup from tanks, Biodiesel is a renewable fuel for diesel biodiesel conforms to ASTM standards lines, pumps, and other fuel system com- engines. Biodiesel, defined by ASTM it can be used in the same equipment as ponents. Be aware, though, that because it International D6751, consists of long- other diesel fuels. Verify with your sup- is such a good solvent, it has the potential chain fatty acid alkyl esters and is made plier that the biodiesel conforms to ASTM to damage certain paints and finishes, so from renewable vegetable oils, recycled standards. always clean up spills immediately. cooking oils, or animal fats. It can be Will I have to modify Will biodiesel hurt seals used at full strength, but it is typically blended with petroleum diesel. A blend of anything mechanically in and other components? 2 percent biodiesel and 98 percent diesel my engine to use biodiesel? Biodiesel blends higher than B20 can is referred to as B2. Other typical blends Not if you are using blends of B20 or cause problems with natural rubber include B5, B10, and B20; pure biodiesel less. The specifications for biodiesel have engine components, such as seals and is sometimes referred to as B100. been established so that it can be used in hoses. Biodiesel will degrade rubber, so any diesel engine. Some modifications any seals or hoses in the fuel system that Why should I consider may be desirable with higher biodiesel are made of rubber will be susceptible to using biodiesel? concentrations. Consult your equipment damage. Biodiesel blends of B20 or below Biodiesel is a renewable, biodegradable, manufacturer before using higher biodie- should not cause problems with rubber cleaner burning alternative to petroleum sel blends. components, but users should periodically fuels. It has a slightly higher cetane check rubber components when using rating, which can promote easier cold Will biodiesel hurt the any biodiesel blend to make sure they are starting and lower idle noise. With tax mechanical parts of my engine? not degrading or getting hard. As the use incentives and rising petroleum prices, No. In fact biodiesel can be good for an of biodiesel increases, most equipment biodiesel is becoming more economically engine for two reasons. First, biodiesel manufacturers are increasing the use of competitive. has more lubricating properties than pe- Viton-based materials in seals and hoses. troleum diesel. Loss of lubricity is one of Viton is a synthetic rubber substitute that Is all biodiesel the same? the drawbacks of newer low-sulphur die- will not be damaged by biodiesel. Because biodiesel can be made from a sel fuels. Adding just 1 percent biodiesel Some manufacturers do caution users number of different raw materials and increases the lubricity to an acceptable about potential problems with the lubri- with a number of different processes, level, so any biodiesel blend will have the cating oil in an engine. If biodiesel gets there can be some subtle variations in required lubricity without sulfur or other mixed with the lubricating oil, it can react chemical and physical properties. ASTM additives. The second advantage is that with the oils to create “sludge” that might has established standards for testing biodiesel will actually help clean the fuel accumulate in the sump or in oil passages. diesel fuels to ensure some uniformity in system. Because it is a good solvent, it can Check manufacturer recommendations caused by biodiesel. Furthermore, many • Drain a small amount of fuel from about oil change frequency, as some sug- manufacturers are reluctant to recommend the bottom of storage tanks every six gest changing oil more often when using use of blends higher than B5 in engines. months to remove any water that might biodiesel. Check carefully with the individual manu- have accumulated in the tank. facturer to verify what is covered and/or • Avoid prolonged exposure of fuel to Will biodiesel cause recommended. light, which can induce algae growth. fuel filter problems? Fiberglass tanks should be painted The most common fuel filter problems oc- Can I use biodiesel in cold and/or placed in shaded areas. cur when switching older machinery from weather? • If biological growth is a problem, the petroleum diesel to biodiesel. Petroleum Pure biodiesel is more susceptible to cold same products that are used with petro- diesel has a tendency to leave paraffin- temperature problems than petroleum leum diesel can be used in biodiesel to based buildup on the insides of tanks and diesel, but when blended, this effect is “dry” the fuel and clean up biological other fuel system components. Biodiesel moderated. A B2 biodiesel blend, for contaminants. will loosen this buildup, which will be example, has the same cold flow proper- How long can I store biodiesel? trapped in the fuel filter. Users can expect ties as petroleum-based diesel. However, Fuel aging and oxidation can lead to to replace fuel filters several times after B20 will have a higher gel point, from heightened acid content, high viscosity, switching older equipment to biodiesel. 3 to 5° F higher. The bottom line is and the formation of gums and sediments After the fuel system gets cleaned out, that as with petroleum diesel, you will that clog filters. It is recommended that filter usage should return to normal. need to use a kerosene blend or other an- biodiesel be stored for no more than six tigelling additive in colder temperatures. Another less common cause of filter months without an antioxidant additive. Consult your fuel supplier to make sure problems comes from the use of higher you will be protected in your climate. biodiesel blends that have been stored for Will biodiesel totally replace diesel some day? extended periods of time. Biodiesel will Is biodiesel more susceptible degrade with age (see storage question to water contamination? There are no specific efforts at this point that follows), producing some gums and to make biodiesel a requirement. Because sediments that can cause filter plugging. Biodiesel is more susceptible to water it is a cleaner burning, renewable fuel contamination than petroleum diesel. source, though, availability and usage will Will I get as much power The presence of water in biodiesel or any continue to increase. from my engine with biodiesel? fuel can promote corrosion of fuel system components and growth of microorgan- Pure biodiesel contains 5 to 8 percent less Where can I get even more isms. The following are some common- energy per gallon than petroleum diesel. information about what sense techniques useful for preventing Blended fuels obviously will have less biodiesel is and the benefits water contamination in any fuel system: of an energy loss. Some literature does of using biodiesel? indicate that other factors such as more • Make sure all tank caps are in place A companion publication to this one efficient burning and better injection and in good condition. (AEN-89) gives more detail about what efficiency due to higher viscosities may • Store machinery with tanks full to biodiesel is, how it is made, and some of counteract this energy loss. In any event, minimize condensation inside the tank. the advantages and disadvantages of the users might notice a slight power loss with Get in the habit of filling the tanks at fuel. There is also a tremendous amount biodiesel fuels. the end of the day so there is no room of information available online through for condensation to form when the organizations such as the National Biodie- Will I void the manufacturer’s temperatures cool overnight. sel Board at