Biodiesel

Published September 20, 2006

Biodiesel is an alternative fuel used in diesel engines. Biodiesel, in its pure form, is not made from petroleum; instead, all or part of it is derived from plant oils or animal fats. In the United States, most commercial biodiesel is made from soybean oil, while in Europe, rapeseed (canola) oil is more commonly used. Biodiesel can be made from virgin oil, or from used cooking oil recycled from restaurants and food processing operations.

As a motor fuel, biodiesel has numerous advantages:

• Biodiesel is a renewable fuel; to make more, we just grow more of the crop needed
• Biodiesel can be produced domestically, displacing imported petroleum
• Biodiesel reduces the amount of pollution emitted from diesel engines.

> Learn more about environmental issues related to biodiesel

Biodiesel should not be confused with straight vegetable oil, which is untreated oil that some people use as fuel in their modified diesel cars. Biodiesel is a more standardized product that can be used in most diesel engines without any modifications. In the United States, commercial biodiesel is defined by ASTM D6751 specifications, which outline specific properties of the fuel, such as viscosity and sulfur content. Rules like the ASTM standard ensure that certified biodiesel burns properly in modern diesel engines. But like conventional diesel fuel, biodiesel can only be used in diesel engines; today’s hybrids with their spark-ignition, gasoline engines cannot burn biodiesel.

Biodiesel can be used in its pure form, which is called B100 (100 percent biodiesel), or can be blended in any proportion with conventional diesel fuel. Common blends include B20 (20 percent biodiesel and 80 percent conventional diesel), and B5 (5 percent biodiesel and 95 percent conventional diesel). According to the Department of Energy, 431 fueling stations in the United States offer commercial biodiesel, although many of these locations sell only low-level blends.