I am having a hard time thinking today.  Need someone to back me up.

If electricity costs .07$ per KWH what is the cost per KBTU?

If propane costs  $1.60 per gallon what is the cost per KBTU?

If natural gas costs $1.25 a Therm what is the cost per KBTU?

This is how I see it:

ELECTRICITY

0.07$  x  KWH           x  1000 BTU    =  0.0205$
KWH       3,413btu          KBTU              KBTU

PROPANE

1.60$            x   gal propane       x    1lb propane   x  1000 BTU =  0.120$
gal propane      5.1 lbs propane        2,622 btus           KBTU           KBTU



NATURAL GAS

1.25$  x  Therm                 x  1000 BTU =  0.0125$
Therm     100,0067 btus          KBTU            KBTU


I believe I have the conversion factors correct (from CRC handbook).  Please double check.  What this does NOT consider is unit efficiency, this is a straight energy conversion.
"I am a slave to dimensional analysis"

the kind of math i use gave me this answer
.07=3412 btus elec
1.6=92,000 btus propane
1.25=100,000 btus nat gas

.07x.293=3412x.293
$.0251=1000 btus elec

1.6/92=92000/92
$.0174=1000 btus gal propane

1.25/100=100,000/100
$.0125=1000 btus therm nat gas

Looks like Natural Gas the cheapest way to heat going... that is until you figure what COP you getting from Geothermal. Even with a 2.0 COP Geothermal is already cheaper than of Natural Gas. Hmm if these figures are correct, than wouldn't an ASHP be more effiecent than Natural Gas? I always thought an ASHP fell somewhere in the efficency scale between Propane and Natural Gas. Don't ASHP's have something like a 2.0 to 2.5 COP?
  

I agree with Heat's Btu content figures but must also consider stack losses for fossil fuels - use the AFUE ratings for gas / oil fired equipment to calculate Btuh delivered to heat the building. Gas and Propane can be burned at efficiencies as high as 95% or so in latest condensing furnaces. OTOH, conventional storage gas fired water heaters run at more like 60%.

Electric resistance heat is essentially 100% efficient. Electric storage water heaters are approximately 95% efficient or can be made so with inexpensive additional insulation.

Not sure if you have oil heat in your area but if so figure 130,000 Btu per gallon. Max efficiency for oil furnaces is 85% since condensing units are not feasible owing to acid problems.

Propane for $1.60 - Arrgh! I paid ~$3.60 per gallon for 800 gallons to fill my underground tank last August, figuring it would only go up as winter approached - how wrong I was!

Thanks for the replies.... I was in a real fog this morning :)

Ouch...

I usually use this online calculator from Hearth.com, you can put geothermal in as electric at 200% for a COP of 2 or 300% for a COP of 3 and so on.

The following links are from an earlier post on the same subject at: http://www.greenbuildingtalk.com/Forums/tabid/53/forumid/13/postid/46196/view/topic/Default.aspx


If your looking for an unbiased calculator that has regional (northeast) up-to-date information try this:
http://nhclimateaudit.org/calculators.php
It has fields that you can change for your local fuel prices and efficiency.

If your looking for a spreadsheet (that is a little more complicated) to run on your computer download this:
http://www.eia.doe.gov/neic/experts/heatcalc.xls

This is good....thanks.