Ethanol can be made from fossil fuels such as natural gas liquids or
coal, but the source that is most valuable is natural raw materials like
sugar cane or grains. This is because the raw material will be remade in
exactly the same way during the following crop cycle. This is a result of
the action of photosynthesis upon the carbon dioxide released during
fermentation at the distillery or combustion in the automobile.
Engine performance and total emissions are both improved by the addition of ethanol to gasoline. The clean burning nature of ethanol allows you to capture more of the work from the fossil portion of the gasoline, which compensates largely for the lower energy content of ethanol itself. In a 10 per cent blend (E10), all other things being held the same, you might get a zero to 2.7 per cent loss in mileage (kilometres per litre).
Another performance benefit from ethanol is its high octane addition to fuel. Of all the commercially viable octane enhancers possible, nothing delivers more punch than ethanol. The populace still feels the ill effects of the tons of poisonous lead that were spewed into urban environments because of the poor decision to accept lead over ethanol as the octane additive of choice.
Comments have been made in the Australian press that ethanol octane benefits due to an increase in Research number is accomplished at the expense of the Motor number so that the benefit cancels. This is simply untrue. Octane is a measure of the resistance in an engine to damaging knock, which is premature detonation of the fuel before the spark plug fires at the optimal point in the cycle of crankshaft rotation. Research Octane Number is measured under normal driving conditions under light load on a level road. Motor Octane Number is best described as pulling a heavy trailer up a hill; that is, the engine is under considerable load. Like all high octane components added to gasoline, the Research number climbs higher with ethanol addition than the Motor Number, but certainly both values increase.
Other benefits due to ethanol in your car are technical in nature, but may be summarized as follows:
The question is whether this greater evaporative mass gives rise to greater pollution potential than the large benefit of exhaust emissions reduction. It is my opinion as a fuel scientist that the nature of the chemical make-up of this new vapour space is less harmful that the unblended, but lower pressure, base gasoline. Ethanol itself, for example, which is now part of the vapour, has a lower ozone-forming potential than olefins and aromatics.
Engine performance and total emissions are both improved by the addition of ethanol to gasoline. The clean burning nature of ethanol allows you to capture more of the work from the fossil portion of the gasoline, which compensates largely for the lower energy content of ethanol itself. In a 10 per cent blend (E10), all other things being held the same, you might get a zero to 2.7 per cent loss in mileage (kilometres per litre).
Another performance benefit from ethanol is its high octane addition to fuel. Of all the commercially viable octane enhancers possible, nothing delivers more punch than ethanol. The populace still feels the ill effects of the tons of poisonous lead that were spewed into urban environments because of the poor decision to accept lead over ethanol as the octane additive of choice.
Comments have been made in the Australian press that ethanol octane benefits due to an increase in Research number is accomplished at the expense of the Motor number so that the benefit cancels. This is simply untrue. Octane is a measure of the resistance in an engine to damaging knock, which is premature detonation of the fuel before the spark plug fires at the optimal point in the cycle of crankshaft rotation. Research Octane Number is measured under normal driving conditions under light load on a level road. Motor Octane Number is best described as pulling a heavy trailer up a hill; that is, the engine is under considerable load. Like all high octane components added to gasoline, the Research number climbs higher with ethanol addition than the Motor Number, but certainly both values increase.
Other benefits due to ethanol in your car are technical in nature, but may be summarized as follows:
- Cleans engine over time, especially harmful combustion chamber deposits.
- Improved front end volatility for better cold start and improved operation (driveability and distillation curve effects).
- Dissolves any fuel line and fuel tank water, which are sources of corrosion, and eliminates them out the exhaust.
- The higher octane of the ethanol blend allows the new cars with higher compression ratio to run without changing refinery operations.
The question is whether this greater evaporative mass gives rise to greater pollution potential than the large benefit of exhaust emissions reduction. It is my opinion as a fuel scientist that the nature of the chemical make-up of this new vapour space is less harmful that the unblended, but lower pressure, base gasoline. Ethanol itself, for example, which is now part of the vapour, has a lower ozone-forming potential than olefins and aromatics.
