Biodiesel: All you needed to know

In between all the ruckus from environmental bodies to curb emissions from automobiles biodiesel has stepped in to make them lay off the offensive and take a breather. Biodiesel is a renewable source of energy that can be used to power conventional diesel engines without any modifications. Here is how,


In the past decade, environmental concerns have grown phenomenally. Another concern is the limited availability of petroleum products because of which alternate fuel has to be discovered to keep economies on track and automobiles on the road. Over the years, many attempts have been made to create and consider alternate sources of fuel for the internal combustion engine. Quite a few options have been considered, among which, bio-diesel looks the most viable option as of now.

Biodiesel is an environment-friendly fuel that can be used to power diesel internal combustion engines. It is made of vegetable oil, animal oil/fat, tallow and waste cooking oil. Transesterification is the name of the process used to convert the ingredients for Biodiesel into the final product. 

Here are the steps of transesterification,

Base catalysed transesterification of vegetable oil and fat with alcohol,

Direct acid catalysed with transesterification of the oil with methanol, 

Conversion of oil into fatty acid, and 

Acid catalysis of fatty acids to Alkyl esters or Biodiesel 

Biodiesel is a renewable source of energy and does not pollute the environment as much as petroleum diesel does. One of its biggest advantages is that it doesn’t require any modification to the diesel engine to be able to tank it up with biodiesel. Also, it can be blended and used with regular petroleum diesel. 

Citroen biodiesel

So, even if your vehicle runs out of biodiesel and none is available at that moment, it can be refuelled with regular petroleum diesel. The downside to blending petroleum diesel with biodiesel is the increased emissions – greater the quantity of petroleum diesel in the mix, more the amount emissions from the engine. 

Biodiesel in its purest form is designated B100, with ‘100’ denoting the percentage of biodiesel in the fuel prepared. Although biodiesel can be used in its purest form in diesel engines, it is usually blended with petroleum diesel. Different blends of biodiesel and petroleum diesel are produced according to the target level of emissions to be achieved. The most common blend of biodiesel available in the market is B20, which consists of 20 percent biodiesel and 80 percent petroleum diesel. 

B100 can damage the natural rubber compounds in the engine by softening and degrading natural rubber seals, etc. This is why B20 grade is a more commonly used biodiesel. Another disadvantage of biodiesel is that it turns into a gel under cold temperatures. The temperature at which biodiesel gels depends on the ingredients used to make it. Once it turns into a gel, it cannot be pumped, as a result the engine will not start. 


However, the biggest problem of all is that making biodiesel requires lots of agricultural land to grow plants such as rapeseed, soyabean, canola, etc. The ultimate argument that this boils down to is, plants for food or fuel. As a result it is highly unlikely that biodiesel is a permanent solution to alternate sources of fuel for the internal combustion engine. 

Biodiesel is available in many fuel filling stations across various nations in Europe and in America. In 2011, 2,21,17,000 tonnes of biodiesel was produced in Europe. 

In India initiative was taken by various bodies and private companies to create biodiesel. Dr. Abdul Kalam, former president of India, was one of the strong advocators for biodiesel production through the cultivation of the Jatropha crop. The Jatropha plant which grows on wasteland was considered as the plant of choice as Jatropha oil produced by the seeds of a plant is an excellent source of biodiesel. India’s biodiesel capacity is estimated at 6,00,000 tonnes per year. 

In many countries biodiesel is subsidised, as a result it is slightly cheaper per litre than petroleum diesel. However, it’s expensive in countries where biodiesel is not subsidised. Price difference between petroleum diesel and biodiesel per litre can hover around Rs. 100 and Rs. 140. But the price difference tends to change rapidly depending on international crude oil prices, subsidies on biodiesel and on the biodiesel rates itself. 

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