Compost heap temperature logger helps keep things hot

compost_temp_logger

HackHut user [lackawanna] is looking to start his own compost pile, but as many urban composters discover, things can get quite smelly if you don’t manage it properly. The process of composting is broken up into two phases, aerobic and anaerobic decomposition. The former is the first stage to occur and produces plenty of heat, but should be scentless. The latter gives off less heat and is more of a stink due to putrefaction. Carefully monitoring the temperature of the pile and restarting the aerobic phase when necessary helps to keep the process “healthy” and scent-free.

[lackawanna] built a simple temperature monitor that he plans on using to track the status of his compost pile once he gets started. It uses an ATmega328 as the brains of the operation and an old metal can transistor as his temperature sensor. Using relative measurements of the compost pile taken in 10 minute intervals, he can determine when the aerobic phase is underway, as well as when things begin turning anaerobic. At that point, the sensor alerts him that the pile needs to be turned.

The build is pretty simple, but leaves plenty of room for expansion. It should be relatively easy to add a more friendly notification interface as well as install multiple sensors to the pile for obtaining aggregate temperature data.

Composting to create hot water

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.

[Thanks Joel]

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