Generate Hot Water With Your Compost Heap

Generate Hot Water With Your Compost Heap

A lot of you may already have compost heaps at home, but you may not be aware of the amount of heat they generate. Environment blogger Rob at One Straw details how he used his heap to heat water in his home.

The idea is based on environmentalist Jean Pain’s thermal compost pile, which stores methane gathered from the pile in large tanks. Because the pile produces so much heat, the tanks must be cooled, which Pain did by wrapping a long hose around them with water running through, the side effect of which is very hot water coming out the other end. While Pain originally used the methane gas to power his truck or electricity, the general idea of creating heat with compost works with or without the methane collection.

While Rob has plans to use old car radiators to use the hot water as a heating system in his home, this may or may not be possible for you. But if you already have a large compost heap out back, you might as well get some hot water out of the deal by pumping some (tank) water through it, and possibly save some money in the process. Hit the link to learn more about the science behind this method, as well as for more detailed instructions on how to build it. Got any of your own favourite DIY projects for saving money on heat and water? Share them in the comments.

The Methane Midden: Epic Sh*t & Jean Pain Composting [via Hack a Day]


  • It’s a very permaculture idea – designing for multiple uses – but unfortunately the bacteria that make compost like it hot. Siphoning off their heat will only slow down their breeding, which will slow down their heat production, so sadly it’s self defeating. That is, unless the climate is so hot that they can stand to lose some, in which case a solar system will do it better. But perhaps for a music festival where there’s lots of compost ingredients and a need for a demountable hws…maybe…???

    • The main blog article explains why he needed to cool the pile:

      “The material for this project was at 140 degrees 3 days ago before we broke down the pile to soak it. Methane production occurs between 85 and about 103 degree. Over about 105 the bacteria start to die off, 101 is about peak production. Jean Pain figured out that you needed to cool the digerster tanks, so he pumped water through a hose wrapped around the tanks.”

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