# Composting biomass for heat



## SolarGary (Sep 8, 2005)

Hi,
I've been collecting material on using a large compost pile for heating water and/or space heating.

The material is here:
http://www.builditsolar.com/Projects/BioFuel/biofuels.htm#CompostHeat

The Jean Pain stuff is very interesting. He used a large biomass pile of finely chipped wood. The pile was about 20 ft in diameter by 10 ft tall. It looks like this single pile provided all of the heat needed for space heating his house and providing domestic hot water for more than 1 year. It appears to be pretty simple -- built up of layers of the wood chips with poly pipe coils embedded in the pile to transfer the heat out. Typically the water was heated to 140F. 
He also included a closed tank in the middle that served as separate anaerobic composting vessel to make methane that he used for cooking, vehicle power and an electric generator. This big compost pile provided essentially all of the power he needed to run his house and vehicle!

A couple other schemes are shown -- the one by Marc looks pretty good to me, and provided heat over a considerable time period.

Some of the other refs seem to indicate that a wide variety of materials might be used (not just fine wood chips).

This has got me to thinking that this is a potentially low effort way to provide some or all of the space heating for a house. It takes quite a bit of effort to make the pile in the first place, but it requires little attention after that, and might provide heat for an entire heating season. In contrast to a wood fire, it does not need to be tended a couple times a day.

I may have access to bales from field that was cut an baled, but the bales were never brought in --they are sitting in a foot of snow in the field. I think I could probably get them for cheap or free. I've been thinking about giving this big compost heap scheme a try with these bales. 

Any thoughts on this? Does it seem practical? Anyone tried it?
See any problems? Any other good references?
This work was done back in the late 70's and early 80's -- wondering why it seems to be little used?

Gary


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## mdharris68 (Sep 28, 2006)

I have read his (Jean Pain) info on the heating with compost and thought that this was a great idea. I thought that using spent hay and manure would achieve the same results but I gave up looking for the right stainless vessel for the methane digester when scrap prices were so high. I think Pain gained some of his heat from the tank, but am not sure about that. Its a great idea and I thought it would provide heat for my barn and possibly run a generator to power it as well. Keep us posted if you decide to go with the hay bales.


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## AngieM2 (May 10, 2002)

you need to be checking out forerunner's threads in Survival forum. He has quite a bit about this subject. He's been doing lots of things with major compost.

Angie


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## MELOC (Sep 26, 2005)

i've been intrigued by this idea since i first saw that it had been tested. it has also been in my mind since a trip to a very large sawmill operation where the piles of mulch covered a 1/4 acre or so each. they created massive amounts of steam in the early autumn chill. a sawmill just 1/4 mile away has some large piles as well and they steam all winter.

i've read some info on the pain stuff as well as MEN's experiments. i don't recall pain's efforts providing heat for so long from one pile, but i may be mistaken. what i remember reading stated he had higher temperatures than 140F ...if i recall correctly. i also seem to recall that wood shavings provided the best cellulose compared to sawdust or other whole debris like sticks and such. some stuff didn't have the surface area to compost fast enough and some stuff, like sawdust, didn't have the staying power to last long enough.

what i remember from the mother earth news experiments was that moisture control was essential for the compost to work properly. i think MEN's pile may have been too small. i also seem to remember that due to the small piles, the pile didn't maintain enough heat to promote composting very well in the coldest weather.

a few thoughts come to mind from all i have read...

it would be good to have a way to aerate the pile and to mix it from time to time.

the pile must be large enough, or protected and insulated somehow, to maintain enough heat to promote composting.

it is probably a good idea to utilize only as much heat as the pile produces in excess considering the needs of the pile.

perhaps a source of nitrogen, like manure, would be a good boost to the pile. 

the method of harvesting the heat must be efficient. i liked the MEN idea of coiling plastic pipe in the pile. however, i have not been able to visualize an efficient method of stirring and aerating the pile without lots of labor or without disturbing the coil. something tells me that the pile would "die" if one undersized it and/or didn't tend it once in a while.

as is, i think the MEN method would work well as a heat source in the shoulder months...september, october and november and in march april and may. i am not so sure about the hard winter.

i have often thought of trying to work with the local sawmill to encourage them to experiment with ways to harvest the heat they generate with their huge mulch piles. i think the only practical way would be for them install piping under the pile and they would not gain nearly as much heat as they could if they were using the piles for heat alone.

while i feel it would be difficult for someone to harvest enough heat to heat a home, i feel it is very possible to heat water for domestic use...within reason.

ok gary, i think some good experiments for you would be to combine some solar collector tech with compost tech. i feel the compost side would be a parasite to the solar at times in the dead of winter, but then again, if the pile is stagnating due to the cold, perhaps in the long term, the two together would work really well.compost would heat all night long if it got a kick in the pants from the solar in the daytime.

another project could be to combine the compost heating perhaps with solar to help heat those problematic livestock waterers that seem to freeze so fast. an ample form of "fuel" in the way of manure should be very handy to anyone who has livestock.


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## SolarGary (Sep 8, 2005)

Thanks All,
Will look into the suggestions.

Still trying to get hold of the guy who owns the field next door to see if he is willing to give away or sell the bales cheap. Think I finally found someone who knows him. There are a total of about 160 bales.

Gary


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## Ken Scharabok (May 11, 2002)

SolarGary:

I don't know about the heat produced by those round hay bales. I am currently feeding out two-year old bales. I have hydraulic arms on the back of a flatbed which allows me to hand a bale in the air. I can then pull off layer after layer using a potato-like, four prong rake. Feed about about a half a bale at a time. No heat in the bale at all from what I can tell.

I suspect it is due to the hay being compacted so densely the bale essentially becomes watertight beyound the first couple of inches.


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## painterswife (Jun 7, 2004)

How about a two pronged attack.

Set it up so that you have room for two to three piles. Bring in manure and other compostables. Heat your home all winter and then have compost to sell to gardners in the spring,

You cover your costs by selling the pile each spring and you heat your home all winter for free,


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## TnAndy (Sep 15, 2005)

Ken Scharabok said:


> SolarGary:
> 
> I don't know about the heat produced by those round hay bales. I am currently feeding out two-year old bales. I have hydraulic arms on the back of a flatbed which allows me to hand a bale in the air. I can then pull off layer after layer using a potato-like, four prong rake. Feed about about a half a bale at a time. No heat in the bale at all from what I can tell.
> 
> I suspect it is due to the hay being compacted so densely the bale essentially becomes watertight beyound the first couple of inches.


Yeah.....Hay that is baled dry won't compost and heat....and it won't wet more than a couple inches in ( think of the thatch roofs in jolly ole England )......so the hay would have to unrolled, wet, and then re-piled.

WET baled hay can and will heat.....and has burned down more than one barn.


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## adamtheha (Mar 14, 2007)

We are going to be attempting to use compost heat to keep an outdoor water tank from freezing. I will post pictures when I've got something up and running. I see that there are some considerations:
Enough water to fuel the reaction
Some heat to kick start composting
Keeping the heat in the pile
Add some nitrogen to react with carbon
Make it last all winter

If nothing else, maybe the compost material will at least insulate the tank from the winter chill!


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## SolarGary (Sep 8, 2005)

adamtheha said:


> We are going to be attempting to use compost heat to keep an outdoor water tank from freezing. I will post pictures when I've got something up and running. I see that there are some considerations:
> Enough water to fuel the reaction
> Some heat to kick start composting
> Keeping the heat in the pile
> ...


Hi -- Sounds interesting -- please do post the pictures -- Gary


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## clovis (May 13, 2002)

Very interesting thread!!!!!


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## commonsense (Jun 1, 2008)

This has always been an idea that has fascinated me, ever since I foolishly stuck my hand into a crack that occurred in the crust of the manure pile--and yanked it back quickly because of the heat! And this was in February! 

I've been kicking some ideas around in my head that involve a confined pile next to a water tank, with a closed loop that is imbedded in the pile with a loop running into and out of the tank. 

I'd LOVE if I could use heated air instead of a fluid, but fluid would probably transfer more heat. 

What's stumping me in the design aspect is how to be able to refresh the pile partway through the winter without having to dig out the entire coil. I have a couple of ideas, and hope to have something installed during December. 

I will take pics when I do get started building.


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## clovis (May 13, 2002)

commonsense said:


> This has always been an idea that has fascinated me, ever since I foolishly stuck my hand into a crack that occurred in the crust of the manure pile--and yanked it back quickly because of the heat! And this was in February!
> 
> I've been kicking some ideas around in my head that involve a confined pile next to a water tank, with a closed loop that is imbedded in the pile with a loop running into and out of the tank.
> 
> ...


Could you use some sort of quick connects?

If you need to put another layer on top, you could coil the hose out, and start piling compost on top, leaving the old coil right in place.

Would that work?

What about running pex or a flex tubing to the compost pile, but use black iron pipe inside the pile? Seems like it could be easy to push and pull back into place.

Just wondering...


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## Ken Scharabok (May 11, 2002)

This biggest problem I see with concept is building the pile to surround the coils and then taking it apart later without damaging the coils. Seems like it would require at least a tractor with a front end loader unless you are willing to trade a great deal of physical labor for winter heat.

If you use wood chips or sawdust where can it be spread once composted?

Electric line tree trimmers went through the area several months ago. They didn't need to haul to a landfill or such as folks would approach them to have the chips dumped on their property. I took a load. When dumped it was maybe 36-48" tall. Now it is down to no more than 14" tall as it has settled. I haven't noticed my cattle having any tendency to sleep on the pile when in the area at night.

Last time they came through was maybe 6-7 year ago. Had a pile dumped then also. I can still tell where it was since very little will grow on it even after all this time.


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## fishhead (Jul 19, 2006)

I know from digging into sawdust piles that they heat for at least 20 years. We dug into one that old and had to quit because it was burning our hands and we only dug down about 4 feet.

I would expect it to heat much longer than a year.


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