The market for wood-gasification boilers is growing in North America. Most are used in rural areas where natural gas in not available, and thus the cost of firewood is often very competitive against the alternatives of No. 2 fuel oil or propane.
In my area of Upstate New York, fuel oil is currently selling for about $3.80 per gal. and propane at about $2.80 per gal. Firewood is available in the range of $65 per face cord. If one assumes a conversion efficiency of 85% on oil, 93% on propane (via a mod/con boiler) and 80% on firewood (burned in a wood-gasification boiler), the unit cost of these fuels is as follows: