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Biodiesel is made from vegetable oils and animal fats

Vegetable oil in a bottle
Vegetable Oil in a Bottle

Source: Stock photography (copyrighted)

Biodiesel is a renewable fuel that can be used instead of the diesel fuel made from petroleum. Biodiesel can be made from vegetable oils and animal fats.

In 2015, soybean oil was the source of about 67% of the total feedstock (raw material) used to produce biodiesel in the United States. Canola oil and corn oil provided about 25% of the total feedstock, and animal fats provided about 9% of the total feedstock. Rapeseed oil, sunflower oil, and palm oil are other major sources of the biodiesel that is consumed in other countries.

Biodiesel is most often blended with petroleum diesel in ratios of 2% (B2), 5% (B5), or 20% (B20). Biodiesel can also be used as pure biodiesel (B100). Biodiesel fuels can be used in regular diesel engines without making any changes to the engines. Biodiesel can also be stored and transported using diesel fuel tanks and equipment.

History of biodiesel

Before petroleum diesel fuel became popular, Rudolf Diesel, the inventor of the diesel engine in 1897, experimented with using vegetable oil (biodiesel) as fuel.

Last reviewed: August 9, 2016

Biodiesel is chemically similar to petroleum diesel

Biodiesel consists of chemicals known as fatty acid methyl esters (FAME). Biodiesel can be used as a substitute for petroleum diesel fuel or as an additive to petroleum diesel fuel.

A biodiesel refinery in Wisconsin
biodiesel refinery near Zistersdorf, Austria

Source: Stock photography (copyrighted)

Biodiesel can be made from a variety of materials

Most biodiesel in the United States is produced from vegetable oils, but it is also made using other feedstocks (raw materials) like waste animal fats from processing plants or recycled cooking oil and grease from restaurants.

Biodiesel can be made from virtually any feedstock that contains an adequate amount of free fatty acids, which are the raw materials that are converted to biodiesel through a chemical process called transesterification. FAME are a type of fatty acid esters that can be produced by an alkali-catalyzed reaction between fats or fatty acids and methanol. The molecules in biodiesel are primarily FAME.

Researchers are working to harvest algae for biodiesel production, because algae contain fat pockets that help them float. This fat can be collected and processed into biodiesel. Continued biodiesel production and use will help the United States meet biofuels consumption levels mandated by the U.S. Renewable Fuel Standard.

In addition to biodiesel derived from FAME, it is possible to make a diesel fuel substitute from cellulosic material like bark or switchgrass. This fuel, sometimes called renewable diesel, also counts toward meeting the U.S. Renewable Fuel Standard mandate. Like cellulosic ethanol, the commercial viability of renewable diesel has yet to be demonstrated.

Last reviewed: September 28, 2015