Death comes to us all. Life's but a walking shadow | I'm not an expert but I'll add a couple of points. Ethanol serves two purposes when added to gasoline. The first is to provide a source of oxygen in order to improve the completeness of combustion, reduce unburnt fuel in the exhaust and reduce air pollution. This requires about 5.6% ethanol. The second is to improve the octane rating of the gasoline. The government arbitraily decided to set that amount at a total of 10% because at the time there was some question about ethanol's effect on older vehicle engines. It is generally understood that today modern engines can tolerate much higher levels of ethanol. The government recently certified 15% in engines built after 2001, I think. Obviously E85 engines are approved to use up to 85% ethanol.
In my opinion what makes this ethanol mileage issue so confusing and unfortunate is that one important factor is overlooked. That factor is the difference in various engines and engine designs. In a very real sense engines are designed for the fuel available not the other way around. It is very feasible to design an engine to use high percentage ethanol and obtain even better mileage than any gasoline-fueled engine but that would require dedicated supplies of ethanol being widely available.
As an example, engines in China were built to use very low quality fuel (low octane) because that was what was available but the engines were low compression engines that were inefficent and produced terrible air pollution. It's my understanding that in China it is expected that people who have modern imported vehicle routinely purchase octane boosters to add to the fuel. As China comes to grips with it's air pollution problem you will probably see the widespread adoption of oxygenated higher octane fuels.
I think just recently someone (Ethanol Insider?) mentioned a big shipment of ethanol to China. In the future our prospects for the price of corn may depend on how China handles it's pollution problem. |
ethanol insider
