Bio-diesel is a non-toxic, biodegradable, and renewable alternative fuel. It is not meant to replace petroleum-based diesel but to extend its usefulness. Bio-diesel can easily be used in unmodified diesel engines. It can be composed of renewable sources such as vegetable oils, waste cooking oil , or animal fats which are chemically reacted with alcohol in the presence of a catalyst. Chemically bio-diesel is described as a mono alkyl ester. Bio-diesel belongs to a family of fatty acids called methyl esters. It is a much cleaner burning fuel while being safer to handle and store than petroleum diesel.