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What is biodiesel?

Very often, a broad, general description is used to define biodiesel in a way that is easy to understand by the general public. However, when these broad descriptions are adopted by an authoritative body as a formal definition, they can include a wide range of experimental fuels that are not biodiesel. The term “biodiesel” has a specific, technical definition that has been agreed to through a painstaking process by members of industry and government which has received full approval by the American Society of Testing and Materials (ASTM), the premier standard setting organization for fuels and fuel additives. That definition is used for purposes such as alternative fuel designation, EPA registration, or other regulatory purposes. Nonetheless, this specific technical definition can be confusing to the general public. We have, therefore, chosen to adopt two definitions for biodiesel. The “general definition” is a simple description for the general public. The “technical definition” should be adopted for use by customers for bid specification purposes or government entities for regulatory purposes.

General Definition of Biodiesel:
Biodiesel is a domestic, renewable fuel for diesel engines derived from natural oils like soybean oil, and which meets the specifications of ASTM D 6751.

Clarifying language to general definition:
Biodiesel can be used in any concentration with petroleum based diesel fuel in existing diesel engines with little or no modification. Biodiesel is not the same thing as raw vegetable oil. It is produced by a chemical process which removes the glycerin from the oil.

Technical Definition for Biodiesel (ASTM D 6751) and Biodiesel Blend:
Biodiesel, n—a fuel comprised of mono-alkyl esters of long chain fatty acids derived from vegetable oils or animal fats, designated B100, and meeting the requirements of ASTM D 6751.

Biodiesel Blend, n—a blend of biodiesel fuel meeting ASTM D 6751 with petroleum-based diesel fuel, designated BXX, where XX represents the volume percentage of biodiesel fuel in the blend.

Clarifying language to technical definition:
Biodiesel, as defined in D 6751, is registered with the US EPA as a fuel and a fuel additive under Section 211(b) of the Clean Air Act.

Biodiesel is typically produced by a reaction of a vegetable oil or animal fat with an alcohol such as methanol or ethanol in the presence of a catalyst to yield mono-alkyl esters and glycerin, which is removed.

 

Further Discussion

EPA Registration and Health Effects Testing. All fuels and fuel additives must be registered with the US EPA and be subjected to the health effects regulations contained within 40 CFR Part 79. Companies must register their individual fuel products with the EPA in order to legally market the product to the public. In order to register their fuel, companies must either complete the health effects testing requirements using their specific fuel, or make arrangements with an entity which has completed the testing, in order to use the other entity’s data. The National Biodiesel Board has completed the required health effects testing on behalf of the biodiesel industry, and has established criteria to make the testing data available to companies seeking to register their biodiesel with the EPA. Any fuel that does not meet ASTM D 6751 is not considered biodiesel and therefore does not fall under the NBB testing umbrella. Adoption of D 6751 by the FTA will assist EPA and the biodiesel industry in preventing unregistered fuels from being illegally sold as biodiesel.

Engine Manufacturing Warranties. Most engine companies have adopted D 6751 to define biodiesel and provide information to customers regarding biodiesel. Other 'bio-derived' materials that do not meet D 6751 may cause engine and fuel system problems and void engine warranties.

 

For additional information on biodiesel see:

• Fuel Fact Sheets
• FAQs
• Biodiesel Specification