Originally Posted by Jon [in CT]
The idea that ethanol fuel doesn't produce hydrocarbon emissions is nonsense. It suffers from the same problems as gasoline, namely that some of the A/F mixture is trapped in crevaces and doesn't burn during the combustion cycle, resulting in unburnt hydrocarbons being sent out the exhaust pipe.
I should not have said that there would not be any HC but huge reductions of them. The increase in the oxygen concentration of ethanol versus gasoline greatly reduces the production of them. Many of the paper I have read about ethanol fuel is that hydrocarbon emissions are very close to zero and in some cases zero.
Secondly the combustion of ethanol, in a perfect sense, would create C02 and H2O, but as we all nothing ever works perfectly. When ethanol combustion does not complete it tends not to create Carbon monoxide and NOx but instead produces Aldehyde's in greater excess than gasoline. Many of todays emission control systems do a wonderful job at destroying or neturalizing many of these poisonous chemicals. More technical info about ethanol fuels can be found here
the second link acutally has a test on a 1978 cab w/o any pollution control devices
In theory if you were utilizing a 100% ethanol fuel and were tuned to use it correctly I would like to see if you would pass a smog test with out any catalytic converters. Obviously you would fail the visual but I wonder what exactly the emissions would be.
edit because I can't spell