Compost Heat anyone?

[Paddy]

Anyone here heard of or are playing with compost heat? There was a French farmer back in the '70's who experimented with collecting the heat from large compost piles. He would lay down 4" perforated pipe first to allow the pile to breath. Then layers of appropriate compost mixed with layers/coils of 1" tubing as the heat exchanger, water filled. Within a week the pile would heat up. Many reaching 140 deg for months at a time

The idea was to circulate the water for heating purposes. This idea is used today to heat greenhouses and anything with radiant pipes. They are talking about large piles, as in several tri-axle dump truck loads. The Carbon to Nitrogen mix is key to get the critters breaking down the material, C/N 30-1. Carbon= wood products, Nitrogen horse, cow manure etc.

Done big enough, they can produce 15,000 Btu an hour. And some piles can produce for two heating seasons if timed correctly, i.e. start the compost pile in the fall.

The end result is heat and a big pile of compost for the garden. I've alway heard a tree rotting in the forest will make as much heat as the same tree burned in a wood stove

I have radiant heat and when I had it installed, I had them design a alternative heat source, for example solar. The main valves open to the alternative source if the source is 105 deg or more.

In any case, sounds cool if you live in an area where wood chips are free and delivered.

Welcome to the Compost Power Network | compostpower.org

 

[Creamer]

I have not heard of that but it sounds real interesting. I will have to look into this.

 

[CalG]

There is a lot of information on the net regarding this subject. Some operations include rather large concrete slabs with water tubing embedded as a "heater" rather than a "heated".

Sophistication includes dedicated turning machines on tracks to turn the piles. One blurb I read included the "tidbit" that there are two "levels" of bugs that decompose the compost, with two "levels" of heat associated with their action. One group of "bugs" runs at quite an elevated temperature. Sometimes requiring adding heat to get the colony established, but once active, the heat output is worth the effort.

I've seen "indoor" rotary composting heaters.. Fill them with the "right stuff", and then turn them on. (Sl..o.o.ow rotation) THe units put out a small homes heat requirements for some period of time.

All these biomass systems appear to be fragile and attention intensive. But, might be useful on many levels.

Heck, the native peoples of Nepal just house their livestock under their living quarters during the winters. The heat of the animals, combined with the decaying bedding and manure serve to take the chill off those cold mountain nights.

 

[Jstpssng]

People have been raising Cole products (cabbage,broccoli,etc) using nothing but compost for heat. I've always thought that they just used it on top of their planting medium, but I could be wrong. I would like to attach my henhouse to a greenhouse before winter to give them a place to scratch, grow a few plants, and hopefully get enough heat to keep the eggs from freezing.
I'll have to check out your link when I'm on a real computer, it sounds interesting and will give me some ideas.
Thanks for sharing.

 

[dave1949]

The Carbon/Nitrogen Ratio

The ideal carbon to nitrogen ratio for composting is 25:1 to 30:1 they say. Assuming that the more rapid decomposition occurs the more heat produced, composting for heat will need to follow this ideal ratio.

Wood chips alone do not decompose very rapidly, a source of nitrogen would have to be planned for and added I believe.

 

[hslogger]

A buddyamine is a certified aborist. He always has had real good tow behind chippers that make chips and not slivers. Most often he hauls the chips back to his semi rural shop. He dumps the chips and has a couple mountains of chips that are as high as a couple stories. On the sides of the oldest pile the chips are composted to fines and he grows his garden there. On the other side of that pile he has a couple lengths of six inch pvc buried. Each end has standard pipe fittings. One one side he runs the water from a spigot. On the other end is the outlet. It produces a huge amount of HOT water that he uses to clean off some of his equipment....... The piles are often dug into and he sells or uses the really well composted stuff for mulch when he plants new trees for clients.