Outdoor wood furnace or geothermal?

I have a 1800 square foot house with a forced air propane system. I am looking to switch to either an outdoor wood furnace or geothermal for heat. Which is more affordable, efficient, reliable ect. How much will it add to my electric bill if I go with geothermal and how much wood will i use if i go with wood? I live in Michigan so we can get some colder temperatures.