Musings of an anonymous geek

February 15, 2006

E85 Ethanol: Uncertain at best

Filed under: Technology — m0j0 @ 1:26 pm

I don’t own, and have never seen (to my knowledge) an E85-capable
vehicle. The pitch that’s being made to the American public by the likes
of GM lately is that E85 is an alternative fuel source that can reduce
our dependence on foreign oil, provide more horsepower and torque
(because E85 is higher octane than regular gas), cut down on pollution,
and some other stuff that I forgot already.

Sure, there’s a supply problem right now. I’m not even going to get into
that, for two reasons: first, it’s kind of a given – of *course* there’s
a supply problem right now. Second, most if not all vehicles capable of
using E85 are also capable of using regular gas, so you can buy one now,
run it on regular gas, and then switch when the time is right or when
the supply loosens up in your area.

My problem is pretty much simple math, actually. What they say is that
you get a 20-25% decrease in mileage because there simply isn’t the same
amount of expendable energy in a gallon of E85. OK, fine. The pricing
for E85 is reportedly anywhere from 3 to 20 cents less, per gallon, than
regular gas. So let’s figure this out using 8th-grade math (at best):

Let’s say I have a car capable of running either E85 or regular gas. For
the sake of round numbers, let’s also say that I have a 20-gallon tank.
Let’s then say that I get 20mpg with regular gas, and 15mpg with E85,
which represents a 25% falloff in performance. That’s going a little
tough on E85 (though not out of the bounds of the claims), so to make up
for it, I’m going to say that regular gas costs $2.50, and that that’s a
full $.50 more than E85 (which *is* outside the bounds of the claims, in
favor of E85!). E85 costs, say, $2.00.

OK, so that means if I just run my car with E85, it costs me $40.00 to
fill my 20-gallon tank. At 15mpg, that means I can go 300 miles for a
cost of $40.00. On a per-mile basis, this amounts to 40/300 or 13 1/3
cents per mile.

If I run this car on just regular gas, it’ll cost me $50.00 to fill my
20-gallon tank. At 20mpg I’ll be able to go 400 miles for a cost of
$50.00. On a per-mile basis, this amounts to 12 1/2 cents per mile.

Did I miss anything? Let me know if I did, because I’m not sure how it
is that this is supposed to be attractive to me. I get less miles per
gallon, which means I have to fill up more often, it costs me more money
to travel the same distance with E85 when compared to regular gas, and
meanwhile I’m still using some (though less) petroleum, and still
producing greenhouse gas.

Also, remember I was pretty nice to E85 here in terms of cost. Let’s be
even nicer. How many miles would I need to get in order for the
cost-per-mile to be equal? After a little doodling, it turns out I’d
need to get an extra mile per gallon from E85 to bring the cost-per mile
down to that of regular gas, but even then, you’re looking at getting
320 miles to a tank of E85 compared to 400 miles for a tank of regular
gas. For my personal daily life, this means that in a typical month, and
adjusting for the tank size in my own car, I’m filling up at least one
extra time per month.

Oh, and by the way, there is no place to fill up with E85 in my home state, at all, as of Feb. 15, 2006.


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