A liquid fuel that can be used in the place of, or mixed with, mineral diesel fuel in modified engines. It is made from a variety of plant oil feedstocks such as rapeseed, soya bean oils, and waste cooking oils. It is converted to fatty acid methyl esters (FAME) by a transesterification process involving the chemical reaction with an alcohol such as methanol in the presence of a strong alkali or acid as the catalyst. The FAME product is separated from the glycerol.