Biodiesel is a renewable fuel manufactured from vegetable oils, animal fats, and recycled cooking oils. Biodiesel offers many advantages:

• It is renewable.

• It is energy efficient.

• It displaces petroleum derived diesel fuel.

• It can be used in most diesel equipment with no or only minor modifications.

• It can reduce global warming gas emissions.

• It can reduce tailpipe emissions, including air toxics.

• It is nontoxic, biodegradable, and suitable for sensitive environments.

• It is can be made from either agricultural or recycled resources.

Biodiesel refers to the pure fuel—B100—that meets the specific biodiesel definition and standards approved by ASTM International.

Biodiesel is a diesel replacement fuel that is manufactured from vegetable oils, recycled cooking greases or oils, or animal fats. Because plants produce oils from sunlight and air, and can do so year after year on cropland, these oils are renewable. Animal fats are produced when the animal consumes plant oils and other fats, and they too are renewable. Used cooking oils are mostly made from vegetable oils, but may also contain animal fats. Used cooking oils are both recycled and renewable.

The biodiesel manufacturing process converts oils and fats into chemicals called long chain mono alkyl esters, or biodiesel. These chemicals are also referred to as fatty acid methyl esters or FAME. In the manufacturing process, 100 pounds of oils or fats are reacted with 10 pounds of a short chain alcohol (usually methanol) in the presence of a catalyst (usually sodium or potassium hydroxide) to form 100 pounds of biodiesel and 10 pounds of glycerine. Glycerine is a sugar, and is a co-product of the biodiesel process

When biodiesel displaces petroleum, it reduces global warming gas emissions such as carbon dioxide (CO2). When plants like soybeans grow they take CO2 from the air to make the stems, roots, leaves, and seeds (soybeans). After the oil is extracted from the soybeans, it is converted into biodiesel and when burned produces CO2 and other emissions, which return to the atmosphere. This cycle does not add to the net CO2 concentration in the air because the next soybean crop will reuse the CO2 in order to grow.

Excerpted from the Biodiesel Handling and Use Guide, US Dept of Energy

Schematic of biodiesel production path.