I built my own wood boiler, I made it more efficient than the run of the mill commercially built unit, I have a pretty leaky 110 year old farm house in Michigan, with pretty much ANY outdoor wood boiler you will burn in the neighborhood above ten full cords of wood in a winter, and that is a real cord 4' x 4' x 8', 128 cubic feet of wood, that is a minimum wood pile four feet wide, four feet tall and eighty feet long.
A normal wood stove will use around half that amount of wood, especially if it is built into a large thermal mass of concrete or some kind of masonry, the new wood gasification boilers are a lot more efficient but also very spendy.
Currently I make biodiesel and heat he place on bio with a good old fashioned oil burning furnace, I collect used fryer oil from area restaurants, you could grow enough soy or canola and press your own oil to make bio to heat the place, currently the finished price of bio using used fryer oil is below $0.70 cents a gallon, just an idea, as I sit here and type where it's 11 degrees outside and 80 degrees inside thanks to bio.