Read once where sod homes of the plains were supplemently heated by piling animal manure against outside walls to compost over the winter to temper, insulate and seal drafts. Good fresh compost for the vegetable garden each spring. Saved on fire wood which was often hard to come bye.

This is awesome to see in practice. Thanks for sharing.

I would imagine that with the application of these methods to modern equipment the results could be even greater.

Has to be / must be a way to turn that heat into mechanical energy to run a generator

The Stirling cycle is the first thing that comes to mind, but in the traditional models, it would require too much of a ▲T gradient for this type of heat source.

Perhaps more applicable to the "slow burn" of compost heat is a large, slow apparatus.

Allow the mound to expand air in a chamber which pushes a small piston to pump water into a tower, or to a drum/tank on a hill. When the piston reaches the end of it's pump stroke the heating chamber is exhausted by the returning piston driven back by weight of the inlet water column. Next, a small volume of cool air is drawn back in to expand again as it is heated.

Essentially this is a simple piston pump (air-over hydraulic) which stores mechanical potential in a water tower. Just dump some of that stored water over a water-wheel to turn a generator when power is needed.

That method disconnects the short high-demand delivery of power from the slow and steady supply. Hydraulic storage of this type is fairly efficient, and if the thermal air-expansion system (a diaphragm, bellows or piston assembly) is buried in the mound and free of pressure-leaks, it should be relatively efficient and long lived too.

This kind of system could be made from common plumbing parts and other hardware-store items. A crankshaft is not necessary if a savvy designer uses linear piston valves, etc. Of course, a natural source of water must be close at hand and some form of elevation change (a hill, a tower, a roof-top vessel) must be nearby too.