Biodiesel, as the name suggests, is made from bio-sources or vegetable oils. Many countries across the world are expanding the production of biofuels and looking at it as an alternative energy source. There is a pressing need to look for renewable energies, as the oil reserves on the planet are plummeting at a steady rate. Most countries have formatted specific laws and policies regarding biodiesel production and use.
Biodiesel is generally made from vegetable oil and the most common is the soy. However, animal fats can also be used to make Biodiesel through a chemical process. The chemical reactions of the transesterification process split the vegetable oil or the animal fats into glycerine and the alkyl esters. It is the alkyl esters that form the fuel, and the leftover glycerine is used to make beauty products and soap. Biodiesel manufacturers also collect virgin and waste oil from restaurants.
During the transesterification process, the vegetable or animal oils react with short-chain alcohols with low molecular weight. Ethanol is preferred because of its low cost, but methanol is the first choice for higher conversions into Biodiesel. The base-catalyzed reaction carries lower catalyst costs and lesser reaction times than acid catalysis. Alkaline catalysis carries the disadvantage of high sensitivity to water and free fatty acids in the vegetable or animal oils.
There are three basic processes involved in Biodiesel production: the pre-treatment, the reaction, and the purification. Let’s know the processes in detail.
- Pre-treatment of feedstock – Common feedstock includes vegetable oil and recycled oil from cooking, storage, and handling. Any impurities and dirt are removed from these oils through the processes of refinement, and removal of water is done during the base-catalyzed transesterification process.
- Base-catalyzed reactions – The lipids react with alcohol to produce Biodiesel and some coproducts like glycerol. Other methods like supercritical reactors and fixed-bed reactors can lower the use of chemical catalysts during transesterification.
- Purification process – As the end products contain Biodiesel along with some by-products, it is essential to carry out purification to remove those by-products. Residual methanol is removed with the help of distillation and any residual water is also removed.
There is further ongoing research on how to improve the Biodiesel production process and the technologies involved. More and more suitable crops are researched for improving oil yield. According to many advocates, waste vegetable oils are the best source to produce Biodiesel. However, the current supply of waste vegetable oils is a lot than what is required for transportation in the world. There are still many challenges that face the production of Biodiesel, such as scarcity of water and land for growing the needed crops. Despite those challenges, Biodiesel production continues to rise and expand.
The biodiesel production capacity across the world has been growing rapidly. The maximum production comes from Europe and the rest from the USA. The total world production of palm oil and soybean oil is more than thirty million tonnes. Under the EPA guidelines, US biodiesel production is all set to achieve new milestones, and the production number has far exceeded the target set by the EPA.