Energy source cost comparison based on expected winter 2004/5 rates - Vashon Island, WA
Oct 9, 2004
Bob Powell
								cost/
			(efficiency)	realized				winter
	btu/unit		AFUE	btu/unit	cost/unit		cost/Mbtu	month
heat pump (ground)	3413	btu/kWh	3.3	11263	$0.07	/kWh	$0.006	$45
heat pump (air-air)	3413	btu/kWh	2.2	7509	$0.07	/kWh	$0.009	$67
wood	19000000	btu/cord	0.7	13300000	$125.00	/cord	$0.009	$68
natural gas	100000	btu/therm	0.95	95000	$1.20	/therm	$0.013	$91
oil	140000	btu/gal	0.85	119000	$2.00	/gal	$0.017	$121
resistive electric	3413	btu/kWh	1	3413	$0.07	/kWh	$0.021	$148
propane	91600	btu/gal	0.9	82440	$2.25	/gal	$0.027	$197
Cost/month is hypothetical for Dec-Mar, for well-insulated small house, constant 10,000 btu/h load
Wood vs. heat pump - if wood isn't "free" the heat pump is cheaper
Wood heat assumes modern sealed stove, burning typical northwest softwood mix
Return to the 70's and past - straight resistive electric is no longer the most expensive heat