Biodiesel is a diesel fuel made from fats or vegetable oils instead of crude oil. It is usually blended into regular diesel in small amounts.
Biodiesel is made by treating fats and oils, such as soybean oil, used cooking grease, or animal fat, into a fuel that burns in a diesel engine. It is renewable, meaning the raw material is grown or collected rather than pumped from the ground.
It is almost always sold as a blend, shown by a B number for the percentage mixed into ordinary diesel. B5 is five percent biodiesel, B20 is twenty percent. The blend levels stay modest because high amounts can gel in cold weather and can affect older engines and their warranties.
For a fuel marketer, biodiesel is both a product and a compliance matter. Federal rules reward blending renewable fuel through credits called RINs, so the blend in the tank is tied to dollars and to paperwork, not just to what the engine burns. It is a separate product from renewable diesel, which is chemically the same as regular diesel and carries none of these blend limits.
In useThrough the warm months the terminal offered B20, but as winter came the jobber dropped back to B5 to keep the fuel from gelling in the cold.
Where the word comes from
The name joins bio, meaning made from living matter, with diesel, the fuel named after Rudolf Diesel, who built the first engine of that type in the 1890s.
See also Renewable diesel, Ethanol blend, RINs / RFS