For some time I have been curious about the use of Ethanol in place of gasoline. I did some googling today, and found a table of energy content for various fuels. You can find the comparisons at the Oak Ridge National Laboratory website.
At the ornl I found what I had been looking for, energy content of various fuels.
A quick summary:
Gasoline 115,000 BTU/gal.
Ethanol 75,700 BTU/gal.
Petro Diesel 130,500 BTU/gal.
The numbers for Bio Diesel were not given in imperial units. However, a comparison in Joules/Liter can be made.
Petro Diesel 36.4 MJ/liter.
Bio Diesel 35.7 MJ/liter.
Ethanol contains only .658 the energy of gasoline.
Gasoline contains 1.519 times as much energy as Ethanol.
Bio and Petro diesel are roughly equal in energy content.
What does this mean? For Ethanol to be equal to gasoline,
1) it should cost 65% of gasoline.
2) you will only get 65% of the mileage on a tank Ethanol compared to gasoline.
3) Diesel beats both, based upon energy content.
You might say, but Diesel is dirty and smelly. I say it doesn't have to be. My 2007, 3.2 liter, 208 hp, V6 diesel powered car a) does not smell, b) does not smoke, c) is locally approved in all but the tree-hugger states. And, I get 29.5 MPG in mixed city highway driving. The 2008, 215 hp, model is approved in ALL states.
I say, process the used cooking oil, and forget about Ethanol. Ethanol belongs in your glass, not in your car.