On Feb 4, 12:31*pm, "HeyBub" wrote:
Prices per MM BTU range from $11.36 for a Masonry heater* to $33.21 for an
electric heat pump.

http://www.popularmechanics.com/home...-efficient/is-...

The best non-weird heating source is Natural Gas at $13.52 per MM BTU.

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* A "Masonry heater" is one in which the hot exhaust gases from a
wood-burning fire meander through your masonry walls, capturing the
otherwise wasted heat before it leaves the chimney.

You have to take into account the relative efficiency of the appliance
that uses it too.

The latter principle you mention sounds extremely dodgy.