Ethanol 5%, 10% blending While going through the paper in ToI/HT Delhi, I saw an ad for Honda City touting it as `technology for tomorrow' because it was E10. What that means is that it can take petrol blended with ethanol to the extent of 10%, or 10% ethanol in a litre of petrol.
The accepted fact is that Honda City is E10 compatible. But what the customers should also know that all other cars that have been launched over the last decade or so are also compatible. That would perhaps not include Amby or Fiat. In fact Brazil uses more than 20% and been using it for 30 years. So much for Honda's nonsense about 10% ethanol engines as `technology for tomorrow'.
As you would know, 5% ethanol blending programme (EBP) has now started in UP, Delhi, Uttaranchal, Karnataka, Goa, Maharashtra (partially), and AP (partially). The EBP programme has not yet been implemented in other states due to high state taxes, excise duties, and levies, which makes the ethanol supply for blending commercially unviable. Over the medium term, the Government plans to increase the ethanol blend ratio from 5% to 10%. What is the impact of ethanol on fuel efficiency.
According to International Energy Agency (IEA), OECD, Oil & Gas Journal, EIA and all other reputed organisations, ethanol has a higher octane number of 120, much higher than that of petrol, which is between 87 and 98. Thus, ethanol blending increases the octane number without having to add a carcinogenic substance like benzene or a health-risk posing chemical like methyl tertiary butyl ether (MTBE). However, the energy content of ethanol is only 26.75 megajoules (MJ)/kg compared with 43.5 MJ/kg for petrol. Thus, the fuel economy of a vehicle running on ethanol-blended petrol would be lower than that of a pure petrol-powered vehicle. In reality, however, the difference is around 30% since ethanol-blended petrol engines can run more efficiently (at a higher compression ratio) because of the higher octane rating. For 5% ethanol blending, the fuel economy disadvantage is estimated at 2-3%. However, fuel economy can be re-optimised for ethanol blends through minor vehicle modifications, such as adjusting engine timing and increasing compression ratio. Some newer vehicles automatically detect the higher octane provided by higher ethanol blends, and adjust timing automatically. A number of studies have tested (or reviewed tests of) the fuel economy impacts of low-level ethanol blends, and have found a wide range of impacts, from slightly worse to substantially better energy efficiency than the same vehicles on pure petrol. However, ethanol is less polluting. For each unit of sugar-based ethanol produced in Brazil for instance, only about 12% of a unit of fossil energy is required. As a result, carbon dioxide emissions calculated on a `well-to-wheels’ basis are also very low, at about 10% of those of conventional gasoline. Is engine modification required or will ethanol damage the car
Ethanol can be used as an automotive fuel by either replacing gasoline outright in dedicated internal combustion engines; or as an octane booster, when mixed (blended) with petrol/gasoline. Ethanol is easily blended up to at least 10% with modern conventional gasoline vehicles, and to much higher levels in vehicles that have been modified to accommodate it. Biodiesel can be blended with petroleum diesel fuel in any ratio up to 100% for operation in conventional diesel engines (small amounts of ethanol can also be blended with diesel under certain conditions). When ethanol is used as a blend in lower proportions, no automotive engine modifications are required. Nearly all recent-model conventional gasoline vehicles produced for international sale are fully compatible with 10% ethanol blends (E10). These vehicles require no modifications or engine adjustments to run on E10, and operating on it will not violate most vehicle manufacturers’ warranties. In blend levels above E10, some engine modifications may be necessary, though the exact level at which modifications are needed varies with local conditions such as climate, altitude and driver performance criteria. In Brazil, cars with electronic fuel injection, including imported cars built for the Brazilian market with minor modifications (such as tuning and the use of ethanol-resistant elastomers), have operated satisfactorily on a 20-25% ethanol blend since 1994, with very few reported complaints about drivability or corrosion. In Brazil, after the government inaugurated the national ethanol programme in 1975, ethanol use has now expanded to account for about 40% of passenger car fuel use, and 15% of total motor-vehicle fuels use. Brazil requires that every gallon of gasoline sold should contain an admixture of 23% ethanol (raised from 20% in November 2006). Thus, for about 30 years and on older generation cars, more than 10% ethanol has been used.
The technology for tomorrow with respect to ethanol is flexible fuel vehicles (FFVs) that use E85. E85 is an alternative fuel that is 85% ethanol and 15%. Vehicles are not modified to run on E85; they are specially manufactured as FFVs. At present, ethanol-gasoline blends above 85% can pose problems for gasoline engines, but pure or `hydrous ethanol (mixture of 96% ethanol and 4% water by volume) can be used in specially designed engines. This type of engine has been in use in Brazil for many years. They are not significantly more expensive to produce than FFVs. |