Biodiesel has a range of advantages and disadvantages. In the U.S. percentages usually range from a low of 2% biodiesel (B2) to 20% (B20). Other parts of the world use 100% pure biodiesel blends (B100).
Diesel engines running on naturally-grown fuels are not a new concept. Doctor Rudolf Diesel developed the first compression-ignition motor in the 1890s as a solution to the wasteful inefficiency of steam engines commonly in use at the time. While he demonstrated an early prototype single cylinder “diesel” engine in 1893 running on peanut oil, he designed a more serious working version for use with traditional petroleum-based fuels were much more readily available.
History
According to Diesel’s own memoirs, one such petroleum fuel engine funded by the Otto Company was shown at an industrial exposition show in France in 1900. At the request of the French government, it was run on peanut oil with no modifications made. It ran so well that many assumed Dr. Diesel had designed it to work with natural oils. Diesel himself was enthusiastic about the use of natural oil fuels, saying “the use of vegetable oils for engine fuels may seem insignificant today but such oils may become, in the course of time, as important as petroleum and the coal-tar products of the present.”
However, vegetable oil fuels faced challenges at that time. Because the only established infrastructure for fuels this engine was capable of running on was thick petroleum heating oil, natural fuels were not given serious merit. And due to thicker consistency, vegetable oil fuels would not mist as easily to achieve complete combustion, leaving behind hardened, burnt deposits on valves, pistons, and other combustion chamber components.
During the 1920s through the onset of World War II, many countries such as Italy, England, Germany, Portugal, Japan, Argentina, and China joined France in experimenting with naturally grown vegetable oils as a fuel source. It was not until 1937 that a patent was issued to scientist at the University of Brussels for a procedure developed where glycerin is removed from fat or vegetable oil by substituting “short linear alchohols” such as ethanol in the place of the glycerol. What’s left is methyl esters, or biodiesel. This was a more advanced form of transesterification first developed in the 1850s, and is credited for the creation of the first usable biodiesel type fuel that did not lead to complete engine gum-up during sustained use.
Biodiesel did not develop further widespread interest and research until several major fuel shortages and high prices occurred worldwide in the 1970s. Serious breakthroughs on the transesterification and refining of sunflower oils to bring them up to diesel fuel standards was achieved by South African agricultural engineers from 1979-83. This tested sunflower oil biodiesel process was sold to an Austrian company Gaskoks that later began full industrial scale production in 1989.
During the early 1990s, European countries such as Sweden, France, Germany, and the Czech Republic began biodiesel production with similar factories. The French government began using biodiesel with vegetable oil concentrations of one-third in public transportation fleet vehicles, and Peugeot and Renault certified diesel engines for heavy trucks to run on such mixtures. By the end of the decade, 21 countries had similar biodiesel development efforts going and today blended biodiesel is available virtually everywhere across Europe.
What Exactly is Biodiesel?
“Biodiesel” by definition is a fuel made up of fatty acids derived from straight vegetable oils, animal fats, tallow, or waste cooking grease (“yellow grease”). Biodiesel can be used in diesel engines completely pure or mixed with petroleum without great modification. Because a common practice is to blend traditional petroleum based diesel fuel with biodiesel, these “Biodiesel blends” are assigned a uniform rating of Bx by the American Society for Testing and Materials International (ASTMI).
In the uniform Bx biodiesel blend rating, the X signifies how much of the fuel is pure biodiesel by percentage. For example, a popular biodiesel blend is B20 – meaning it contains a blend of 20 percent biodiesel and 80 percent traditional petroleum diesel fuel. Pure biodiesel is known as B100. In the United States, lower percentages of biodiesel are usually blended with petroleum – from 2% (B2) to 20% (B20). But in other parts of the world such as Europe, higher-level blends up to B100 are used.
Some notable facts about Biodiesel
Even a small addition of biodiesel (1% to 2%) will provide better lubricating properties (“lubricity”) for fuel injectors and fuel pumps than low-sulfur petroleum diesel introduced in 1994 does, and it has much better lubricity than the ultra-low-sulfur petroleum diesel introduced in 2006. Additionally, a 2% blend of biodiesel (B2) reduces greenhouse emissions significantly. While bench tests of engines running on pure biodiesel B100 have shown increases of NOx levels (which lead to smog formation) up to 13%, other tests of B20 have shown only a 2% such increase. It should be noted that some evaluations which measure all criteria during road tests with engines operating under normal load conditions have actually shown a decrease in NOx levels when biodiesel is used.
While traditional petroleum diesel fuel gels at temperatures below the freezing point of water, biodiesel made from animal fats or yellow grease will gel at the same temperature as the grease or fat that was used to make it – often times, that’s around 60 degrees Fahrenheit. When this happens, wax crystals have formed causing the fuel to thicken and become a gel that cannot be pumped through fuel lines. However, biodiesel made from thinner canola oil has a much lower gelling temperature of 14 degrees Fahrenheit.
Unless you’ve created the biodiesel fuel yourself that you plan to use in your vehicle, it’s often hard to know exactly what you’re getting, and at what temperature point the fuel will become unusable. A safe precaution to avoid this is equipping your vehicle with two fuel tanks – one for traditional petroleum diesel and the other for biodiesel. This way, the engine can be run on traditional diesel fuel when first started until the biodiesel and fuel lines reach a normal operating temperature.
Since the biggest risk is turning the engine off and letting things cool with unknown mixtures of biodiesel still in the fuel lines, it’s advisable to switch back to the traditional diesel tank to ensure all biodiesel is washed out of the fuel lines before shutoff. In the shop, I’ve seen cars towed in from owners using biodiesel who did not heed these precautions. The fix was to replace clogged fuel filters and clean out fuel lines that became clogged with higher-fat biodiesel that gelled at warmer temperatures. While that may sound simple, the process was time consuming and resulted in hours of unpleasant labor charges – something that defeated the cost-saving nature of using biodiesel in the first place.
Anti-gel diesel additives are available that chemically alter the fuel to inhibit the formation of wax crystals in cold temperatures. It should be noted that additives designed for traditional petroleum diesel do not work effectively on biodiesels, but there are anti-gel products on the market designed for B20 blends (Powerservice Arctic Express Biodiesel Antigel) and even B100 (Biofuel Systems Wintron XC30).
The natural energy content of B100 biodiesel is approximately 10% lower than traditional petroleum diesel fuel – a difference that will be noticeable when accelerating and when the engine is under load conditions. Mileage may or may not drop similarly depending on how much load your engine is under. It is possible under moderate-throttle conditions such as highway driving, fuel economy may actually be higher because of the higher lubricating qualities of biodiesel fuels.
Similar to gasoline or traditional diesel fuel, biodiesel has a shelf life of approximately 6 months before it begins to break down. In the case of biodiesel, it will grow mold just the way petroleum diesel does because both are “hygroscopic” and readily absorb water vapor from the air. It’s more likely biodiesel will have water in it from the start because many biodiesel manufacturers use water to wash components of their fuel and do not always properly separate it out.
