Biodiesel fuel is one of the alternative fuels being studied. It is renewable and produced from a variety of new and used vegetable oils and animal fat. It is a liquid fuel that is made up of fatty acid methyl esters, fatty acid alkyl esters or long chain mono alkyl esters. It is cleaner burning and a great replacement for petroleum based diesel fuel. Pure biodiesel or that mixed with petroleum can be used to fuel diesel cars. Its physical properties are similar to those of diesel fuel, but there are emissions and safety benefits to using biodiesel instead. It is nontoxic and also biodegradable.