Compost Heating

[Jafo]

We are building a camp up in the Adirondack State Park on some property my family and I have owned for a gagillion years. There is no electricity available so all energy you have to furnish yourself. I have been looking for some off the wall ways of heating the place without say, propane or wood and have been thoroughly fascinated with all the info out there about using compost piles to heat water. It seems wherever you search, you find the pioneer of this was a French man by the name of Jean Pain:

http://en.wikipedia.org/wiki/Jean_Pain

Anyway, it basically consists of coiling a bunch of polypipe into a large compost pile made of finely shredded brush, leaves (generally debris found on the forest floor). You water it as you build the pile and according to the experience of Mr Pain, when completed (and when composting begins), you should be able to run water through the pipe and heat it to around 140 degrees for up to 18 - 24 months. He supposedly heated his entire home (including hot water). He also collected the gas emitted from a barrel in the center of the pile that has compost tea in it. He would use that for his stove and also to fuel his truck.

I have TONS of material and free access to a pretty beefy wood chipper, so I am thinking this may be a project for me in the spring. Anyone here ever try this before?

 

[Adios Pantalones]

I have not, but I have extensive composting experience. You will notice steam coming off wood chip piles in cool weather. Wood chips will heat like this, but they are generally nitrogen deficient. If the heat produced isn't sufficient, then a larger pile of material could help- but addition of a "green" (such as grass clippings) would get it cooking. The heat won't last very long if this is primarily finer materials like leaves- it will compost hot but quick.

Watering as you build is important because the material will mat up and water won't get where it's needed - the center will be too dry.

edit: a few more things- a pile that's cooled off can be kicked up again by mixing, but it will be a shorter heating cycle. Piles that are too large will not get air to the center, and will be less efficient, but I saw that this size is something like 6x6x6' before it's an issue.

There have been cases of large compost piles spontaneously catching fire; although rare- it's something to look into. Turning a pile you will sometimes see what looks like ash in the middle from a fire, but it's a white mold spore and nothing to worry about (usually means more water or a good mixing is needed).

 

[Seasoned Oak]

I would think the effect of the cold water pipes would tend to dampen the composting action. so when you need the heat the most it wont be producing any.

 

[timfromohio]

I have not tried it but follow this guy's blog and he has done exactly what you are describing:

(broken link removed)

 

[Adios Pantalones]

I would think the effect of the cold water pipes would tend to dampen the composting action. so when you need the heat the most it wont be producing any.

I have got piles to 165F in the middle. It is somewhat self-catalytic, but slowing the pile down a bit with water flow may be a good thing, as it will extend the useful life of the pile. It will slow in winter, but making it large enough means that the outside layer will act as its own insulation. I have had piles stay active all winter in NH.

 

[fossil]

Bend Oregon Bulletin article, August 15, 2011:


Mulch fire damages Tumalo area home

Published: August 15. 2011 4:00AM PST

At 3:43 a.m., a caller to 911 reported smoke in an Arrowhead Drive home north of Tumalo. Firefighters found smoke coming through a stove vent, and located the fire in an exterior wall, according to a news release from the Bend Fire Department.

About a week ago, bark mulch was installed at the address and was touching the siding and foundation, the release said.

The mulch “spontaneously ignited†and spread to the inside of the wall, burning through a plastic water line that helped contain the fire. Firefighters opened the wall and put the fire out. The blaze caused $27,000 of damage, the release said. No injuries were reported.

 

[Jafo]

What I was considering doing was filling a 50 gallon drum with coiled polypipe and filling up the remainder of the drum with water. I would have an inlet and outlet pipe. I would cap and seal the drum and then bury it inside the mulch pile, wetting each layer. Since this is a camp, most of the time we won't be there. During this time, the heat in the pile would slowly heat the water in the barrel. Water, tends to hold heat for a while, especially when insulated. Then when we did use the water, we would run it through the polypipe and it would transfer heat from the water in the barrel better than it would if it were directly in contact with the mulch. It would be a more gradual heat exchange I would think. I would think if these was ever a solution for HEATING, the water would have to be heavily mixed with anti-freeze for obvious reasons..

My sons and I were already going to build a compost pile this weekend for next years garden, in fact, I have been collecting manure from some local farms for the last few weeks. While we were making the "lasagna" I decided to coil up an old hose in the center of the pile. I kept water pressure on the hose. What the hell? If it works, I can give the dog a bath outside with the hose and not freeze his butt off lol..

 

[GaryGary]

Hi,
Some more variations on the heat from compost scheme here:
http://www.builditsolar.com/Projects/BioFuel/biofuels.htm#CompostHeat

The one Marc did seems fairly practical.

Gary

 

[Jafo]

Yes, I have seen all of that.. I pretty much googled it out. Today I ran the hose that I have through the new compost pile.. I didn't use a thermometer but it was definitely warm but nowhere near HOT. About the same as a warm swimming pool. Occasionally colder water will come through, I am thinking that is from part of the hose being in a cold part of the pile. It is definitely getting hotter. I don't want to pull too much heat out of it so I am going to let it sit for 3-4 more days before I try it again.

 

[woodchip]

I have had trenches in a greenhouse filled with composting materials in previous years to warm the soil for raising early plants.

There is no doubt that composting does produce heat.

My only thought is how much heat can you take out of the composting process before that process is compromised and just stops before the process is complete.......

 

[Jafo]

I have had trenches in a greenhouse filled with composting materials in previous years to warm the soil for raising early plants.

There is no doubt that composting does produce heat.

My only thought is how much heat can you take out of the composting process before that process is compromised and just stops before the process is complete.......

I have always wondered that too.. I am assuming if the system was a closed loop heating system, once it got up to temperature, it would not remove as much heat as running cold water through the pipes..

 

[begreen]

Compost heat scavenging seems a natural for heating greenhouses.

 

[midwestcoast]

Sure will be interesting. I think your idea of heating a mass af water over a longer period, then extracting when you need it is a good one. Do you think 50 Gals will be able to store enough heat to supply your intermittent load? How much heat would 50 gals of water hold at 140 degrees?

Edit-------

Oh and by the way, I'm totally jealous of your camp in the ADKs! Sweet!

 

[Jafo]

Sure will be interesting. I think your idea of heating a mass af water over a longer period, then extracting when you need it is a good one. Do you think 50 Gals will be able to store enough heat to supply your intermittent load? How much heat would 50 gals of water hold at 140 degrees?

Edit-------

Oh and by the way, I'm totally jealous of your camp in the ADKs! Sweet!

Thanks!

I am thinking the barrel might hold enough heat for a 5 minute shower, maybe? Keep in mind, the water never leaves the barrel, only the heat does as the water travels through the polypipe transfers the heat from the water in the barrel. If it were a closed loop system, I am thinking you could run it under the floor of the camp as radiant floor heating. I would prefer the shower instead..

 

[Adios Pantalones]

The length of the hose running through the pile is a major issue, probably a lot more than cooling off the pile. You need a whole coil spread out through the pile- garden hose doesn't transfer heat through the wall very well, and it's the amount of time the water is inside the pile (amongst other things) that determines how much heat you put in the water. Lay a couple coils out, dump on compost, put a couple more coils on that, more compost, etc etc.

 

[Jafo]

The garden hose is more or less an experiment and btw, I ran it the other day and the water was about 98 degrees, still a ways to go I think. I am not using the Jean Pain style compost pile though, where he just shreds wood and and organics from the forest floor. My compost pile is basically just leaves, horse/chicken manure, kitchen scraps and dirt..

 

[Redbear86]

Probly use wood boiler or aftermarket kits for heating water in a wood stove for shower/faucet water but i think this could work to keep the cabin from freezing up while your not there, what about digging a deep pit for the compost pile and burying the water line (and maybe foam pipe insulation) from the pit to the house, the earth would add an extra layer of insulation and a little fire protection if you were to have combustion, maybe a tarp or landscape/pond liner rubber over the top of the compost pit. I've seen sealed bags of compost steaming from decomp so i'm not sure if you can "choke" it out easily----discuss....

 

[Jafo]

I am worried that if it was buried and covered the composting organisms would suffocate?

 

[Redbear86]

yea i'm not sure how much oxygen exactly is needed, but if you go to home depot and pick up a few of the 10lb bags of composted manure you can see how warm they are towards the middle of the pallet, and they're in fairly well sealed plastic bags and supposedly past they're "hottest" stage of composition- snow melts on on those pallets in the wintertime here and in Montana i know from experience- i use compost to heat individual clear plastic domes over my rose bushes every winter, the bottom of the dome is seated pretty deep (3-4 inches) in compost on the outside to create the best seal i can, i'm sure its not airtight if there was any kind pressure "pulling" in but it works nicely--- i know from my college days mold can grow inside an airtight tuperware container in the fridge (38 degrees), ewwwww-lol