In .com> "Mad Scientist Jr" > writes:

>I did not find consistent numbers, for instance Wikipedia says Ethanol
>produces 27% less energy than gasoline, which would be 0.73 the amount
>of energy from gasoline, but a USA Today article says one gallon of
>E-85 has an energy content of 80,000 Btu - compared with about
>118,000 Btu for a gallon of gas, which would be 0.67 BTUs per gallon of
>gas.

Just addressing this one point, using figures
from Our Very Own Federal Gov't:

Linkname: EPA - OTAQ - Fuel Economy Impact Analysis of RFG
URL: http://www.epa.gov/otaq/rfgecon.htm

regular gasoline: 108,500 -> 117,000 BTU/gallon
depending on winter vs. summer blends
and other factors.

ethanol: 76,100 BTU/gallon.

If we take the midrange of gasoline there we'll get 112,750.

So.. pure ethanol vs gasoline: 76,100 : 112,750 = 67.5 percent

I'll let you work out the E-10 and E-85 mixes...

NOTE that some folk claim engines designed for
the inherent higher octane in ethanol can use higher
compression, and thus eke out a bit more efficiency,
(and, to a lesser extent, "regular" engines might
be able to do so as well), but... there ain't no
way that'll compensate for a 1/3rd reduction in BTUs


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