Hereâs a simplistic way of looking at the economics of woodburning. An air-dried cord (4âx4âx8â) of shagbark hickory, white oak or sugar maple contains about 30 million BTUs of heat energy. Theoretically, if this cord of wood is burned in a high-efficiency, air-tight woodstove (~70% efficient), the firewood would provide 21 million BTUs of useable heat. A gallon of propane contains about 90,000 BTUs of heat energy. If the propane fueled a high-efficiency gas furnace (~90% efficient), it would provide about 81,000 BTUs of useable heat. Now, if propane was selling for $1.60 per gallon, the energy value of one cord of hardwood would be about $415/cord (ie, 21 million divided by 81,000 times $1.60). If youâre currently burning propane and your firewood is free, the money youâd save by burning firewood would pay for the new woodstove and chimney installation (~$2,500) after burning only 6 or 7 cords of firewood. Of course, if youâre burning a lower quality wood or wood that isnât fully seasoned, the savings wouldnât be as great. One also has to consider that the heat from a some wood-burning appliances (ie, freestanding woodstove or fireplace insert) is not circulated around the house as effectively as heat from a gas furnace.