Bio-diesel is obtained from animal fat or vegetable oil. It consist of long chain fatty acid which are usually mono-alkyl ester. The bio-diesels are produced by a process known as transesterification. During this process from vegetable oil we will remove glycerin which will form methyl ester (i.e) bio-diesel and glycerin. The bio-diesel can be used alone but often it is combined with a small proportion of other additives.