I have 3' of fall leaves in my winter
chicken run. This winter it was often below 0F out there, some nights in the -20s. Normally the
chicken poop forms a frozen crust on the top. This year I got
coffee grounds and dug in a new spot each week and put in 10 gallons of grounds (room temp). I mixed them up with the leaves in the hole and covered them up with surrounding leaves. From January onward I had hot (or at least warm) composting going on.
I'm tempted to try to replicate this process in a more mobile form next winter. I'm imagining a 55 gallon drum full of leaves and 5-10 gallons of coffee grounds mixed in. Add
enough water to make it happy. Vent holes in the ends and a stand to rotate it on every few days. IF it worked, it would be like a big wimpy space heater. I could put one under the chicken roost, one under a seedling table, two in my
wood shop. Just have to empty them out and reload with fresh leaves and grounds when they run out of steam.
Just an idea, we'll see if it works...