Bio-diesel refers to a vegetable oil-or animal fat-based diesel fuel consisting of long-chain alkyl (methyl, ethyl, or propyl) esters. Biodiesel is typically manufactured by chemically reacting lipids like vegetable oil, animal fat with an alcohol producing fatty acid esters.In other words it is a form of diesel fuel manufactured from vegetable oils, animal fats, or recycled restaurant greases. It is safe, biodegradable, and produces less air pollutants than petroleum-based diesel.Biodiesel can be used in its pure form (B100) or blended with petroleum diesel.Common blends include B2(2 percent biodiesel), B5, and B20.Most vehicle manufacturers approve blends up to B5, and some approve blends up to B20.