Had looked at this in my list of thinking. Problem are multi-fold from my reading. Compost containers that small cool to the outside and basically less than half of it will produce decent heat because the outsides cool too much to cook properly.
The answer was to insulate the perimeter of the containers. The guy was putting 4 containers in a square block and insulating the bottom and the outside perimeter of the square and the top. To reduce the chance of hitting the lines while turning the compost he was burying the coils vertically rather than horizontally. He was digging down half a container into another container. Then playing
bucket brigade with the halves of all the rest of the containers. Then returning the first half removed into the last hole. Which brings the second problem. This looked like a major lot of work to regularly turn the piles to keep them running. Surely there has to be a better answer.
So now my silly thinking on the issue.
Digging around the coils buried even vertically is going to be a pain. What if we did away with them? Ideally we want to be able to easily remove the heat recovery. So what if we used heat pipes or heat probes instead of loops to bring the heat up from the compost? They could then be stabbed down into the compost instead of buried in it. Thus reducing labor some and risk a bunch. Heat probes are a pipe inside a pipe. The water goes down inside pipe and comes up the outside.(borrowing this from a shallow well geothermal heat system but the outside pipe would need to be solid metal so it can be driven into the pile instead of the poly pipes used in the geothermal system.) The other answer is heat pipes. They are an evacuated tubes filled with a small amount refrigerant. Run the water bath around the outside of the top head end. The refrigerant can be water, alcohol or ammonia or a number of others. Heat pipes would self regulate how much heat was pulled better but are more complicated to build. Either way daisy chain a bunch of them together in some combination of parallel and serial to extract the heat. Monitor outlet water temperature to know if we are pulling too much heat out. Shut down if the pile is cooling to much.
Still a lot of labor to turn the soil to aerate it. Can we do away with that too? What if we built a probe on an air blow gun. Is it possible to aerate the pile by injection of air in multiple locations one after another. With 90 psi to 120 psi we
should be able to push air in. Will it just blow back up the outside of the tube or will it spread out and lift an area of the pile while putting air in? Multiple injection sites and multiple depths. Or maybe bury a bunch of vertical tubes when the pile is created. Tie a bunch of them together in group. Create 3 or more groups. Then rather than probing multiple times simply slug the whole pile with air in one tube group. Use different groups each time to encourage settling and sealing around the unused groups to hopefully not end up with a single air leak up out of the pile.
2
