A Compost Heated Greenhouse

Alacrates's picture

I wrote an article about an experimental greenhouse project undertaken by the New Alchemists in the 1970s, that attempted to use the heat generated from about 25 cubic yards of composting material to heat a greenhouse through a Vermont winter.


Basically, blower fans were mounted at the top of greenhouse, that connected through ducts to the bottoms of the compost chambers, aerating the compost materials from below.

Secondary fans located above the compost chambers drew heat and exhaust gases from the compost, and expelled it into a layer of mature compost and seedbed soil, which allowed carbon dioxide to circulate up into the air within the greenhouse, but kept ammonia gases trapped within the soil layer, increasing the nitrogen content of this 'bio-filter' base layer of the greenhouse.

Even with some insufficient carpentry in the greenhouse shell, they managed to avoid freezing over the '84-85 winter in Vermont, the lettuce and parsley crops coming through unscathed.

The experiment was written up in a journal entry, and apparently abandoned, but the details of this experiment have been expanded into a mature system, by the Agrilab Technologies company, that allows agricultural operations to harvest a substantial amount of heat and energy from compostable materials, manure, farm wastes, etc.

Anyways, if it's of interest to you, let me know what you think. Thanks!

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ClareBroommaker's picture

Thank you; I read from your blog. The topic is interesting and the work clever. It ties in with an old timey bit I was reading this afternoon. I found a 2003 reprint edited by Michael Pollan of the 1821? American Gardener, by William Cobbett, the second chapter of which is "On the Making and Managing of Hot-Beds and Greenhouses". I have not read much of that yet, though, because I keep skipping around the book plucking little humorous bits to amuse myself.

Alacrates's picture

Thanks, that is interesting to hear... I'm pretty sure people have tinkered with various ways to heat seedbeds for a very long time.

Sweet Tatorman mentioned that (I believe) George Washington Carver had mentioned ways of using buried compost heat to warm up sweet potato seed beds?

The book that I was reading on this mentioned a Chinese practice of burying decomposing materials beneath seedbeds, and of the northern European practice of heaping manure along the walls of a farmhouse to increase the temps!

Perhaps I shouldn't have called this the "First Compost Heated Compost", hehe, but I think it might've at least been the first to heat a greenhouse entirely from compost heat in this manner!

~ Daniel

David Trammel's picture

There is a type of dug in green house called a "Walipini", that I think would go well with the idea of heating with compost, because you would be maximizing the insulation factor. Here is a link to a blog post about it.

Build a $300 underground greenhouse for year-round gardening

BTW, I moved your post to the Gardening and Compost Circle.

Alacrates's picture

Ah, that is an interesting article - I bet a dug-in greenhouse could help with this concept, related to the insulation provided by the earth! In a cold, northern winter, every degree counts!