Tonight I was hunting ways to warm a house without using the power grid.
I was thinking back to Texas when their power went off and the temperatures froze and the disasters in people's homes as their pipes froze and burst.
Of course there is the option of wood burning stove and there are even portable options that can be piped out a window or tent. There is also solar heat options that can store the heat.
But I also found Pain Mounds!
It is a big compost pile that generates enough heat for hot water and can be used to warm a house or greenhouse! Straw bales are stacked in a circle and the middle is filled with wood chips and manure .. tubing and piping is coiled up inside the mound and extending out the side for heat transfer to location of choice!
This option provides heat for an entire year with hardly any maintenance whatsoever after setting up the pile and everything can be re-used ... and the best part is it can be used as compost to grow food when the year is done and the pile cools!
Check out these pictures: