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Biodiesel is a renewable fuel

Vegetable oil in a bottle
Vegetable Oil in a Bottle

Source: Stock photography (copyrighted)

Biodiesel is a renewable fuel made from biomass. Most U.S. biodiesel is produced from vegetable oils and animal fats. Biodiesel can be used in the same equipment as diesel fuel made from petroleum.

The major sources of feedstock (raw material) for making biodiesel in the United States and their shares of total biodiesel feedstocks in 2017 were

  • Soybean oil—52%
  • Canola oil—13%
  • Corn oil—13%
  • Recycled feedstocks, such as used cooking oils and yellow grease—12%
  • Animal fats—10%

Rapeseed oil, sunflower oil, and palm oil are major feedstocks for biodiesel produced in other countries.

Biodiesel is most often blended with petroleum diesel in ratios of 2% (referred to as 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 blends are also used as heating oil. Biodiesel can be stored and transported using petroleum 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. Until 2001, only small amounts of biodiesel were consumed in the United States. Since then, biodiesel consumption has increased substantially, largely because of the availability of various government incentives and requirements to produce, sell, and use biodiesel.

Last updated: June 11, 2018

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 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.

Algae is a potential source 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.

Last updated: June 11, 2018