Ethanol blending: A technological knowhow!
Ethanol blending is a process of adding ethanol to petrol. Because of the growing environmental concerns, the use of ethanol as a motor fuel or as an additive is gaining rapid popularity. Properties of Ethanol closely resembles petrol. Moreover, you can obtain ethanol from various plants making it a renewable fuel.
Properties of ethanol:
Chemically, ethanol i.e. ethyl alcohol (C2H5OH) is a clear, colorless and flammable liquid. It has an octane number of 108 which is higher in comparison to standard gasoline.
Various sources of ethanol:
Ethanol can either be manufactured from petroleum products or from biomass. In the former case, ethylene is the raw material whereas, in latter, various plant-based materials serve the purpose. Ethanol obtained from the material of plant origin is called bio-ethanol. Sugarcane, Maize, Potato, Sweet-potato, agricultural waste are some of the major raw materials for the production of bio-ethanol. Fermentation of plant material of this ilk yields ethanol.
Nomenclature of ethanol fuels:
Worldwide, the automotive industry has adopted a standard nomenclature to denote ethanol fuels which is EX.
Here, E stands for Ethanol. X is a number denoting the percentage of ethanol in fuel by volume.
According to the above nomenclature, E10 means fuel that contains 10% by volume of ethanol.
Similarly, E50, E85 refers to fuels having 50% and 85% by volume of ethanol.
Advantages of ethanol blending:
- Ethanol has a higher octane rating compared to petrol. Thus, petrol containing ethanol reduces knocking tendency of the engine.
- Compared to petrol, ethanol is cheaper. Therefore, ethanol blending offers a cheap substitute for gasoline.
- Because of its possible bio-origin, it is a renewable source of energy.
- It helps to reduce vehicular pollution as combustion of ethanol produces less CO and SOX.
Disadvantages of ethanol blending:
- The energy content of ethanol is low (almost 35%) than that of petrol. Thus, vehicles running on ethanol have poor mileage.
- Ethanol is corrosive in nature. Hence, the use of a higher percentage of ethanol may corrode engine parts.
- Natural rubber dissolves in ethanol. Thus natural rubber components, if any, need replacement with some special grade of rubber.
- Ethanol has a high affinity for water which leads to 'phase separation'. This means that if ethanol blended petrol comes in contact with water, the entire portion of ethanol separates from petrol. It causes two separate layers of water and petrol. This may lead to engine stalling.
Global scenario of ethanol blending:
Countries like the United States, Brazil and some parts of Europe employ higher blends of ethanol like E50, E85, and even E100. The Indian government has recently introduced the E10 mandate and is planning to extend it to E20.
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