Biodiesel

Biodiesel is made from vegetable oils by transesterification. The process of transesterifcation can generally be described as follows.

A fat or oil is reacted with an alcohol, like methanol, together with a catalyst to produce glycerine and methyl esters (the chemical name of biodiesel). The methanol is charged in excess to assist in quick conversion and recovered for reuse. The catalyst is usually sodium or potassium hydroxide which has already been mixed with the methanol.

The process results in biodiesel and glycerine. The glycerine is a valuable by product. Biodiesel can be mixed with petroleum diesel at any blend. Blends are coded like B100 or B20 where the number reflects the percentage of biodiesel of the fuel. So B100 means the fuel is 100% methyl esters of biodiesel whereas B20 means 20% of the fuel is biodiesel and the remaining 80% is regular diesel derived from fossil fuels.

Diesel engines can run on pure biodiesel (B100) with little modifications. In effect the engine itself can run on biodiesel without modifications but due to the higher acidity of the biodiesel, rubber elements and fuel lines that are exposed to the oil should be changed with materials that can endure the higher acidity levels. For blends not exceeding 20% of biodiesel (B20) these modifications are not necessary.

Biodiesel has lower emissions compared to fossil fuels and especially when the car electronics of the engine of the vehicle running on biodiesel have been modified for biodiesel combustion the emissions can be even lower.