How Ethanol is Blended in Petrol and What is its Production Process

Nowadays, terms like E10 and E20 are frequently seen at petrol pumps, which mean that 10 per cent and 20 per cent ethanol, respectively, have been added to the total quantity of petrol. The Government of India is promoting the blending of ethanol in petroleum. The primary objectives behind these steps include reducing crude oil imports, providing better market opportunities for farmers for their crops, and reducing pollution caused by vehicles.

Ethanol is a type of alcohol, known in chemical terms as 'Ethyl Alcohol'. Its chemical formula is C₂H₅OH. Ethanol is used not only as fuel but also in the manufacture of sanitisers, medicines, and various chemicals. When this substance is mixed with petrol, it is known as 'ethanol blended petrol'.

Various natural sources are used for the production of ethanol in India. Ethanol is primarily prepared using sugarcane juice, sugarcane molasses, sugar syrup, maize, damaged or broken grains, and surplus rice. The specialty of this process is that the residual material from the sugarcane used to make sugar can also be used to prepare fuel for vehicles. The government has promoted grain-based ethanol production along with the sugar industry.

The most important process in making ethanol is called 'Fermentation'. In simple terms, this is a process in which yeast converts sugar into alcohol. At the beginning of the production process, a solution is prepared by mixing sugarcane juice or molasses with water. Subsequently, yeast is added to this solution, which breaks down the sugars present in the solution to produce ethanol and carbon dioxide. After some time, alcohol begins to form in this mixture.

However, the substance prepared through fermentation is not directly suitable for mixing with petrol, as it contains water and other impurities. Therefore, a process of 'Distillation' is carried out thereafter. At this stage, the mixture is heated, causing the ethanol to separate as vapour. This vapour is then cooled to bring it back into liquid form. But distillation alone does not remove all the water present in the ethanol.

To use it as fuel, it is necessary to further purify the ethanol. For this, modern technology such as 'Molecular Sieve' is used to remove the remaining water, resulting in the preparation of 'Fuel Grade Anhydrous Ethanol'. When ethanol is made from grains, the starch present in them is first converted into sugar with the help of enzymes, and then the processes of fermentation and distillation are followed. In this way, sugarcane and maize produced in fields become part of vehicle fuel through industrial processes.

After ethanol is prepared, it is not taken directly to petrol pumps for mixing. First, its quality and purity are strictly checked. Subsequently, oil companies blend ethanol and petrol in the prescribed proportions at their refineries or depots. This entire process is carried out by automatic and controlled machines. Calibrated systems are used to measure the exact quantity of both fuels, ensuring that the prepared petrol meets the prescribed quality standards. This blended fuel is then transported to petrol pumps via tankers. This is not a manual mixing process, but a controlled industrial process.

To understand this process, examples of E10 and E20 can be taken. E10 means that in one litre of fuel, there is approximately 100 millilitres of ethanol and 900 millilitres of petrol. Similarly, E20 contains 20 per cent ethanol and 80 per cent petrol. Here, 'E' stands for ethanol, and the number written with it indicates the percentage of ethanol in the fuel.

According to a report by Aaj Tak, India has achieved the target of 20 per cent blending in petrol by the ethanol supply year 2025-26. Data from the Ministry of Petroleum indicates that in 2024-25, the average blending reached 19.24 per cent.