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Biodiesel Offers Clean Fuel Alternative for Diesel Engines

Burning Veggies Reduces Reliance on Foreign Oil Sources


Biodiesel Fuel Pump

Biodiesel infrastructure has been growing, with fuel stations offering biodiesel blends dotting the countryside.

U.S. Dept. of Energy

If corn is king with ethanol enthusiasts, it’s the lowly soybean that most often steals the show in the biodiesel world. But what exactly is biodiesel and how is this alternative fuel being used?

Biodiesel is categorized as a clean-burning alternative fuel and as such, is produced from renewable resources. While it contains no petroleum itself, it can be blended at various levels with conventional diesel fuel, much like ethanol and other types of alternative fuels are blended. A big plus for the use of biodiesel is that it can be used in regular diesel engines without having to go through an engine conversion process or other type of major modification.

Why biodiesel?

The traits that make biodiesel a good choice are much like those of any other alternative fuel: it’s made from a renewable resource, so it’s better for the environment and has lower emissions compared to petroleum-based fuels. And although it may be hard to think of a motor fuel in this way, biodiesel is actually less toxic than simple table salt and it will biodegrade about as fast as sugar. Biodiesel proponents are also quick to point out that biodiesel from domestic resources, such as soybeans, helps to lessen the country’s dependency on foreign oil sources.

Although concerns have been raised over biodiesel engine performance compared with conventional diesel, in fact, biodiesel has a higher cetane number than U.S. diesel fuel. The National Biodiesel Board reports that in more than 50 million miles of in-field demonstrations, B20 (a blend of 20 percent biodiesel) showed similar fuel consumption, horsepower, torque, and haulage rates as conventional diesel fuel. The NBB says biodiesel also has superior lubricity, and it has the highest BTU content of any alternative fuel, falling in the range between #1 and #2 diesel fuel.

Making biodiesel

Transesterification is the somewhat-complicated term for the actual chemical process that leads to the formation of biodiesel. But if you understand the process, you’ll understand where the term comes from. When making biodiesel, glycerin—a liquid byproduct—is separated from the vegetable oil or fat of the source plant. This leaves two products, methyl esters (which is actually the scientific term for biodiesel) and the glycerin itself, which is a valuable byproduct used extensively in other industries to make things like cosmetics, soaps—even animal feeds.

But if all this talk about using vegetable matter to produce biodiesel has the wheels turning in your head, slow them down—biodiesel is not the same thing as raw vegetable oil. Any biodiesel expert worth his weight in beans will tell you that fuel-grade biodiesel—the kind that will ensure correct engine performance—has to be made according to strict biodiesel industry specifications.

The industry is also proud to call itself the only alternative fuel to have fully completed the health effects testing requirements of the 1990 Clean Air Act Amendments. Biodiesel that meets industry standards can be legally sold and distributed as a motor fuel as long as it is also legally registered with the U.S. Environmental Protection Agency. So, raw vegetable oil—because it can’t meet any of those criteria—is not considered biodiesel.

Because wording and definitions for biodiesel are often used in state and federal statutes now, or by various governmental departments, there is an official definition of biodiesel that meets not only federal and state law requirements, but also Original Equipment Manufacturer, or OEM, guidelines. This definition is:

Biodiesel is defined as mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats which conform to ASTM D6751 specifications for use in diesel engines. Biodiesel refers to the pure fuel before blending with diesel fuel. Biodiesel blends are denoted as, "BXX" with "XX" representing the percentage of biodiesel contained in the blend (ie: B20 is 20% biodiesel, 80% petroleum diesel).


So where can you find it? Biodiesel is available across the nation and fleet managers/owners will find it can be purchased directly from biodiesel marketers and producers, as well as from petroleum distributors. You will also find a growing number of public pumps for biodiesel dotted around the country. The newly revamped U.S. Department of Energy website has an area at the top of its homepage that allows you to input your zip code and bring up a map showing alternative fuel pumps of all kinds, including biodiesel blends.

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