Quote Originally Posted by dljosephson View Post
This series of topics has really been thrashed over the years. There is, I think, only one consistent reason for not trying to wash the ethanol out of fuel to be used in airplanes, and it's mentioned in only a few of the articles and posts. Ethanol is added to low-octane fuel stock for one reason: to raise the octane rating without using tetraethyl lead. When you take the ethanol out (assuming you do it properly, dispose of the waste properly, etc. etc.) you have lower octane fuel. If your engine is happy with 73 or 80 octane, "washed" autogas is probably okay. But if you are looking for 91/96, it's not likely that you'll be able to get it by washing even premium autogas.

(This is off topic and I will look for another thread to continue it, but my main concern is what modification is needed to make a regular aircraft engine work well on E85 or even E99. The FAA teardown report on the IO-360 they ran with AGE85 was not good news.)
This is not entirely true - in modern times, ethanol was prescribed as an oxygenate in California to reduce pollutants. It became used later as a replacement for MTBE, not TEL, since MTBE was the original replacement for TEL for vehicles. When a few fuel tanks were found to be leaking MTBE, fears over the potential for groundwater pollution lead to widespread use of ethanol to increase engine's resistance to detonation. BigAg and the biofuels lobby of course promoted this vigorously. Interestingly, overseas ETBE has been the main octane-boosting additive. The US is the world's leading producer of ETBE, but most is shipped overseas. Many in the US have the same knee-jerk reaction to ETBE as to MTBE, due probably to ignorance that the two are like comparing apples and oranges. (So much for our education system...) ETBE however is in use in European aviation fuels as an octane booster, and it is hinted that GAMI's 100UL fuel may use it also.

The only modifications we need regarding ethanol are to our laws - the best would be a complete repeal of EISA 2007 that created the ethanol production mandates in the first place. Let free markets determine our energy production, not bureaucrats and crony capitalists.