As most people know, Biodiesel is an organic liquid fuel, fuel additive or extender, used as a petrodiesel substitute. Made basically from animal tallow, but more made often from oils such as rapeseed, soybeans, canola, and sunflowers, waste vegetable oils, or microalgae oils. Although, this fuel can also be made from ethanol or hydrocarbons derived from several agricultural products such as rice hulls.

However, Biodiesel is also a term that has a technical definition that was agreed to through a process by members of industry and government, receiving full approval by the ASTM (American Society of Testing and Materials), the premier standard setting organization for fuels and fuel additives. The official definition is used for purposes such as alternative fuel designation, EPA registration, or other regulatory purposes, but this specific technical definition can be confusing to the general public.

With this concept duality has forced some organizations to adopt two definitions for Biodiesel, one labeled as the general definition which is a simple description for the general public, and the other the technical definition, adopted by government entities for regulatory purposes, as well as for other business usages.

The technical definition for Biodiesel is a Biodiesel Blend, both meeting the requirements of ASTM D 6751, remarking that Biodiesel is a n-a fuel comprised of mono-alkyl esters of long chain fatty acids derived from animal fats or vegetable oils designated B100, while Biodiesel Blend is a n-a blend of Biodiesel fuel with petroleum-based diesel fuel, designated BXX, where XX represents the volume percentage of Biodiesel fuel in the blend.

To make it easier, the public definition, declares that Biodiesel is the domestic, renewable fuel for diesel engines derived from natural oils like canola, soybean oil, or virgin oil that meets the specifications of ASTM D 6751. This fuel can be used in any concentration with petrodiesel fuel in any existing diesel engines with little or no modification at all.

Something that people must know is the fact that Biodiesel is not the same thing as ordinary raw vegetable oil. The fuel is produced after a chemical process called transesterification which removes the glycerin from the oil.