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Old June 2nd 07, 06:23 AM posted to rec.aviation.homebuilt
Roger (K8RI)
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Posts: 727
Default Fuel prices-BTU's per Gal.

On Thu, 31 May 2007 10:56:21 -0500, Barnyard BOb
wrote:


Jerry Wass wrote:


Doing the simplest conversion---168.3/250.0--= sp.gr.of 0.6732..

0.6732X 8.34(#/gal for h2o)= 5.614 #/gal for Avgas--agreeing with
you--but isn't right---I'm gonna weigh things again--might have been off
on my tare weight. Jerry

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I don't keep avgas at my house. However....

Weighing 250 cc of 60 degree F. mogas = 190 grams

Specific gravity = 190/250cc = 0.76

0.76 x 8.34 = 6.3384....

MOGAS = 6.3384 lb/gal @ 60 degrees F.

More than close enough for GW Bush gov't work!


A more relevant number is the BTUs per gallon which translaes into MPG
for a given engine.

Automotive gas in California is about 111,500 BTU while E85 is about
81,000, or 72% Straight Ethenol is roughtly 60% or 66,600 BTU.
Alcohol costs more while giving much less energy and MPG. IOW just
going from straight gas to E85 a trip that takes 50 gallons of gas
will take at least 69.5 gallons of E85.
Given todays car gas prices of basically $3.20 per gallon (it's near
$3.50 in michigan) if we take that 50 gallons of gas for a trip at
$3.50 it's 175 USD. Given the same price for E85 (which is actually
more expensive) we come up with $243.25, or an extra $68.25 for the
same trip using E85.

Alternative fuels are in general more expensive to use or implement
than gas. For those fuels to become viable alternatives the cost of
gas is going ot need to go to at least $3.50 a gallon and stay there.

Except for small scale implementation, Hydrogen is much more
expensive.

I spent some time with a consulatant a couple weeks back. His
conclusion for me to go a combination of active and passive solar
power would easily run bet ween $30,000 and $50,000 for this small
home. Yes, I could sell power back to the power company, BUT our rates
are about 8 cents per KWH whichmakes for a very long pay back if I
don't have to purchase any power. Add to that, maintenance on the
syatem and it really starts to get expensive.