Biofuels are fuels which are in some way derived from biomass. The term covers solid biomass, liquid fuels and various biogases. Some important categories of Biofuels are Bioalcohols & Biodiesel.
Bioalcohols are the biologically produced alcohols. Ethanol fuel is the most common biofuel worldwide, particularly in Brazil, because of its Sugar Industry.
The Bioalcohols are produced by fermentation of sugars derived from wheat, corn, sugar beets, sugar cane, molasses and any sugar or starch. Ethanol is used in petrol engines as a replacement for gasoline; mostly blended up to 15%. But please note that it can be mixed with gasoline to any percentage.
Ethanol v/s Gasoline
- Please note that Ethanol has smaller energy density than gasoline. This means that it takes more fuel by volume and mass to produce the same amount of work. This is the major reason why we don’t use 100% Ethanol and use only a blend of Ethanol.
- The major advantage of Ethanol is that it has a higher octane rating than ethanol-free gasoline. The Ethanol increases engine’s compression ratio for increased thermal efficiency . Further, at higher altitude locations, a few countries a a mandatory mix of gasoline and ethanol to reduce atmospheric pollution emissions.
- However, higher octane ratio makes higher compression ratios that will make gasoline engines subject to engine knocking. This can reduce efficiency or damage the engine if knock sensors are not present to retard the timing. So both the above are the reasons that Ethanol is blended in Gasoline.
India and Ethanol blending
The Ethanol Blended Petrol (EBP) programme earlier launched by the Government could not sustain owing to non-availability of ethanol in required quantity and other state specific issues. Later, to give fillip to the programme, Government gave fresh relook and decided on 16.8.2010 to implement the EBP programme to the extent of the ethanol made available by the domestic ethanol producers at the ex-factory declared price decided by the Government.
- As per the Government decision, after ascertaining the actual availability of ethanol in the country, percentage of blend from 0-10% would be recommended area-wise by the working group of officers constituted for the purpose.
- Government fixed provisional price of ethanol at Rs. 27 per litre.
- The programme was re-launched in November, 2010 after fresh tenders issued by the OMCs for sourcing ethanol.