Want nature to supply you with 130-150 degree hot water? [Onestraw] shows you how to get just that by building a compost heap that heats water. Finding himself the proud owner of a dump truck of green wood chips [Onestraw] went about building his own version of Jean Pain's thermal compost pile. The idea is to produce and store methane generated from the compost pile but in order to do so, the temperature must be kept fairly low. The microorganisms in the compost generate a lot of heat trying to break down that matter and running water through the system will keep the temperature low enough for the methane-producers to be happy. The side effect of this cooling system is hot water coming out the other end. [Onestraw] even has plans to use salvaged car radiators to turn the hot water into a heating system for his home. Granted you're not going to add this to your apartment, but if you have space and waste plant matter and need hot water this is a great way to get it. Read more and comment at HackAday