Re: [GBlist] Cost per BTU

[Sacie H Lambertson <dlambert@grasshoppernet.com>]

At 09:39 AM 28-02-01 -0500, you wrote:
>Can anyone direct me to where I might find comparative costs per BTU for
>electric, oil and propane energy for my locale?

David, this from my files and similar to David Foley's response, may be
more than you want, but is interesting.   Sacie Lambertson
--------------------
Fuel Conversion

One bit of data, in this calculation, that only you can most easily and
accurately provide, is the cost per purchased fuel unit at your site:

Such fuel associated costs might be labeled:
$/therm of gas (100,000Btus/therm),  
$/Kwh (3,412Btus/Kwh ?), 
$/cord firewood (80-120,000Btus/cord ?), 
$/Square Foot of Solar Aperature (100,000Btus/SF)
$/LPG (propane) @ 95,475 btus/gal.
$/Coal (lignite) @ 14,940 btus/lb.
$/Kerosene @ 137,900 btus/gal.
$/#2 Oil @ 138,690 btus/gal 

The parenthetical Btu numbers give you a basis for comparison, before
efficiency losses - except for the solar number, which is pretty much the
effective end use equivalent gain.  And since the fuel cost of the solar
thermal systems would be, in fact, zero; one would want to
estimate an installation and maintenance cost for the solar part, and
compare that initial expense against the attributable displaced fuel, or
the savings, over time - and then project how long it would take to break
even.

Since these are DELIVERED btus/unit, they ought to be all adjusted for what
we used to call externalities - for example transmission losses + the
energy needed to generate electricity might actually triple the btus/kWh to
11,600.

As mentioned the other factor is efficiency - 400%+ for some geo-thermal
systems, 100% for electric baseboard, -30% for an old pot belly coal stove,
10% for most PV systems. We often reduce these radically based upon system
efficiency - ductwork, air in hydronic systems, but that is more a judgment
call.