Pain's estimates for methane extraction and it is not known if anyone has been able to reproduce his results. Pain's compost heaps generated hot water via of pipe buried inside the compost mound. The pipe was wrapped around the methane generator with an inlet for cold water and an outlet for hot water. The heat from the decomposing mass produced of hot water heated to — enough to meet central heating, bathroom and kitchen requirements. The heap composted for nearly 18 months, after which it was dismantled. The humus was used to mulch soils. Heater silo The composting process runs in an airtight container inside a house. The heat can be radiated directly to the interiors of the house or distributed by a heating circuit. An additional water pipe can be vertically built into the silo for warming water. The silo is the central part of an in-house compost heater. In autumn the silo is filled up with fresh biomass, after which the silo delivers comfortable heat throughout the winter. Inlet air and outlet air provide the necessary oxygen. The outlet air goes out of the house. Silo moisture is higher than in a regular compost heap. The decay process produces additional water, which is drained at the bottom of the silo. A part of this water enters the top of the silo for better distribution in the processing volume. If pumped periodically or continuously to the top to rinse through the silo, the whole system becomes a wet composting system. References Composting Heating, ventilation, and air conditioning Permaculture concepts