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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 2016, soybean oil was the source of about 55% of the total feedstock (raw material) used to produce biodiesel in the United States. Canola oil and corn oil were the source of about 22%, recycled grease about 13%, and animal fats about 10% 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 updated: July 27, 2017

Biodiesel is chemically similar to petroleum diesel

Biodiesel consists of chemicals known as fatty acid methyl esters (FAME). Biodiesel is used as a substitute for or additive to petroleum diesel fuel. Biodiesel production and use helps to meet biofuels consumption levels required by the U.S.Renewable Fuel Standard.

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. Other feedstocks (raw materials) include waste animal fats from processing plants and recycled yellow grease (used cooking oil and grease) from restaurants.

Biodiesel can be made from nearly any feedstock that contains adequate 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 use algae for biodiesel production. Algae contain fat pockets that help them float. This fat can be collected and processed into biodiesel.

In addition to biodiesel derived from FAME, a diesel fuel substitute can be made from cellulosic material such as wood or switchgrass. This fuel, sometimes called renewable diesel, may also count toward meeting the U.S. Renewable Fuel Standard requirements. Like cellulosic ethanol, the commercial viability of renewable diesel has yet to be demonstrated.

Last updated: August 10, 2017