Hacking the Heat

by James McSweeney

Conan Eaton in front of the world’s first documented aerated in-vessel compost heat recovery system at Auburn Star Farm in Lunenburg, Vermont.
Conan Eaton in front of the world’s first documented aerated in-vessel compost heat recovery system at Auburn Star Farm in Lunenburg, Vermont.

In 2012, Highfields research program embarked on a journey to unlock the keys to successful utilization of one of composting’s most underutilized by-products: microorganism’s metabolic heat. We’ve known for a long time that there was a tremendous energy resource lost to the environment that could be put to productive use and add value for compost and agricultural producers.

We partnered with our fellow hackers of the heat and crowd funded $40,336 through kickstarter with 310 backers. Now we’re deep in the “Discovery” phase of a research & development project that will design and build a compost heat recovery system to heat Highfields’ worm parlor, shop and office, and make information and designs on compost heat recovery available to the composting community.

Over the winter we’ve been studying systems that have been tried by partners such as Conan Eaton at Auburn star farms. Last year Conan harnessed heat from his composting dairy manure to offset around $1,900 worth of kerosene and this year he stands to match if not exceed that. The system is the first we are aware of to combine compost heat recovery with in-vessel and aerated static pile composting.

What’s more, the heat exchanger is nothing more than a 1200’ black poly irrigation pipe. The system supplies a re-purposed farm-all radiator (the heater) with a continuous supply of hot water/glycol mix to heat a barn. All together it cost around $20K to build and can hold 120 cubic yards of raw compost. Our work with Conan has spanned design, recipe, management, and now data collection compost heat recovery optimization.  We plan to integrate pieces of Conan’s design into ours as it develops.