I have a geo-thermal heat pump.Most likely the cheapest method of heating and cooling known today.Not everybody could benefit from this method though because of a lack of a water source.That plus the initial cost is pretty high unless you do as I and install it yourself.I also got the unit very cheaply to begin with.
It's less expensive but not free,thus the woodburner .
What just about everybody can do is increase the insulation in your homes.That will in time more than pay for itself,plus no maintainence.I have 18" in my attic,would have put more but also would have ran out of room to put it.The anticipated heat lose is 30,000 btu's per hour at zero degrees .So it takes that much just to maintain what heat is there.The geo is twice that big, so no prob.With the woodburner cooking ,it never or seldom comes on,even at zero.