Biodiesel is an alternative fuel source derived from animal fats and vegetable oils. It is environmentally safe, non-toxic, and able to be 100% domestically made. Biodiesel is fast becoming a favorite alternative to traditional diesel among fleet owner operators, because it is a cost-effective way to meet the stringent emissions demands set forth by the federal government.
Biodiesel manufacturing requires strict attention to detail and strict adherence to production standards in order to ensure a high-quality final product.
Major Steps in Biodiesel Production
- Feedstock Pretreatment – Waste vegetable oil, or WVO, is filtered, removing dirt, charred food, water, and all other extraneous materials.
- Free Fatty Acid Processing – A standard base solution is used to titrate the clean oil, determing free fatty acid concentrations. Afterwards, the fatty acids are esterfied into biodiesel or bound glycerides or removed.
- Transesterification – A reactive base such as sodium hydroxide is combined with ethanol in sufficient quantity to cause a reaction to the triglycerides found in feedstock oil, converting them into ethyl esters, or biodiesel.
- Purification – After the esterification process is complete, the biodiesel must be separated from the glycerin and excess alcohol that remains. The biodiesel will be used as a fuel additive, while the glycerin will be used in beauty product manufacturing.
Transesterification is the process of reacting the triglycerides found in vegetable oils and animal fats with an alcohol, usually ethanol or methanol to produce ethyl esters and glycerol. The ethyl esters, or biodiesel are used in fuel blends, and the glycerol is used in soaps and other hygiene products.
In a natural setting, this transesterification reaction is either exceedingly slow or non-existent. To synthesize biodiesel, heat and an acid or base are used to cause a rapid esterification of the triglycerides within the oil or fat. Note that the neither the acid or base used are consumed by the transesterification process, thus they are catalysts not reactants.
Almost all biodiesel is produced from virgin vegetable oils using the base-catalyzed technique. This technique is the most economical process for treating virgin vegetable oils. It requires only low temperatures and pressures and provides a 98% biodiesel yield. However, biodiesel produced from other sources or by other methods may require acid catalysis for transesterification, which is a much slower method.