An old miner where I lived in Colorado told me a rule of thumb was, to heat a cabin for the winter, you need the equivalent cabin volume of wood. I had a 25 X 20 X 8 ft building and cut 15 cords of wood (1 cord is 128 cu ft). Sure enough, half way thru the winter, I ran out of wood.

If you have geothermal available, it is semi easy to heat with it if the water is free of a lot of minerals. I have seen reports of pipes plugging up if the water is heavy mineralized.

I still think that there is enough hot air in Washington, DC to solve our energy problems.