But if you are measuring the energy content in BTU than the 34% fewer miles per gallon are already taken into account. It takes more gallons of ethanol to get the same BTU's of energy as a gallon of gas.
There are numerous contradictory studies about the energy gain or loss from ethanol production.
BTW, it is completely legal to distill ethanol for fuel. This site has the government permit form you need to fill in. More interestingly, that same site says you can get tax credits for pure ethanol used by a buisness. So distill your own fuel and the government will pay you to run your trucks on it. I didn't know that.