Introduction: Compost Heating System

The Pain Mound is a large pile of woody biomass, aka mulch. Invented by French farmer Jean Pain in the 1970s, it is made of woodchips and sawdust, surrounded by a ring of hay bales for structure and insulation. As the Pain Mound decomposes, heat is produced and harnessed using a hydronic loop. The Pain Mound will produce heat for up to 18 months, after which time the remains (nutrient rich, earthy humus) can be used to build soil.

Step 1: Lay Out the Mound

Stake out a circle approximately 12 feet in diameter. Purchase hay bales from a local farm, collect fallen trees and branches, and rent a chipper. A load of sawdust can usually be procured from a local sawmill: they will often deliver for a nominal fee.

Step 2: Create a Hay Bale Backstop + Add Aeration

Lay about 15' of perforated 4" tubing at the bottom of the mound, with each end protruding out of the perimeter. Create a "backstop" of haybales to catch the woodchips as they are thrown from the chipper into the mound. Chip a layer of woodchips approximately 1' high into the mound on top of the aeration pipe.

Step 3: Lay the Hydronic Loop

Coil 1/2" plastic pipe at the bottom of the mound and hold it down temporarily with cinder blocks. Run the end of the pipe outside of the ring of hay bales, to be connected to your water source.

Step 4: Chips and Sawdust!

Chip wood into the pile, intermittently stopping to throw shovelfuls of sawdust in. The high carbon content of both materials create a lot of heat when decomposing.

Step 5: Continue Laying Water Pipe + Building Up the Mound

Once you get started, this project should take 1-2 days of labor. Keep looping in water pipe and building up the hay perimeter as you add woodchips and sawdust. Throw in some manure - any animal will work - if you have any.

Step 6: Fill Line With Water

The Pain Mound can be used to heat hot tubs, greenhouses or hydronic heating systems. Plan out your location carefully ahead of time so that you are close to the thing you will be heating. In the diagram shown here, we hooked up a pain mound to a greenhouse. We buried the water lines so that we would not lose additional heat to the outdoor air.

For more information, CompostPower.org has an excellent detailed installation guide, which can be found here: http://www.compostpower.org/node/24

Step 7: Track the Heat Output

If possible, consider including a series of temperature sensors with your water pipes, so that you can track the BTU output along the way. Our mound produced more than 6 million BTUs over a period of 12 months, including a freezing New England winter.


Collaborators: Garth Schwellenbach and Jesse Selman

Comments

author
AwaitingA made it! (author)2016-08-27

Can anyone tell me why plastic piping is always used as the coil?

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cassioppe made it! (author)cassioppe2016-11-03

I am making one this year's and plastic is cheapest. I tried shop for copper or other tubing but the cost is prohibiting. like thousands of dollars as compared to plastic tubing being 230$

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mikaelvisby made it! (author)2016-06-21

And....two more questions:

The wood chips shoud they be made from fresh trees or "dead" threes or maybe it doesnt matter?

How much and water did you add and did you do it all the time or just "like" each 10' or so....

author
mikaelvisby made it! (author)2016-06-21

Loooove you great instructions!!!

Still...whats the ideal size of the woodchips?

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MTeodor made it! (author)2016-01-28

Hi, I am impressed! Will make it asap here in RO.

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mark.johnston.7186896 made it! (author)2015-03-08

Just wanted to know how long did your pile last ...as i am in Romania and fixing to build almost the same one you got there in the pics

author
ionut_mystic made it! (author)ionut_mystic2016-01-28

Ai reusit in cele din urma? :D

author
silgan.samirtnok made it! (author)2014-11-20

And please translate what means BTUs. I'd like to transfer to kWh. :) we mesure heat in different ways :) thnx for help ;)

author
MichaelB292 made it! (author)MichaelB2922015-12-08

I'm sure you can do that, here's a tip: 1 BTU = 0,000293071 kWh

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MichaelB292 made it! (author)2015-12-01

In what month did you do this?

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MichaelB292 made it! (author)MichaelB2922015-12-08

Nevermind. I just saw the graph. ... Another question. What was the overall cost of the set-up?

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bulau65 made it! (author)2014-05-30

Piles of compost can catch fire spontaneously! Watch out when storing compost too close to your house.

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katrinaspade made it! (author)katrinaspade2014-05-30

You are right! Some towns have a minimum height of 8' for compost/mulch piles, for that reason.

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adillbeck made it! (author)adillbeck2014-11-03

So, a small pile will catch fire easier than a large pile?

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katrinaspade made it! (author)katrinaspade2014-11-03

Oops, my apologies! That should be "maximum"...

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adillbeck made it! (author)adillbeck2014-11-03

That makes a little more sense. I just didn't know if there was some weird trick with heat dissipation in large piles or something. Contemplating making a fairly small one and putting it inside of a make shift greenhouse. Basically just plastic over a dome... Curious if it could keep it warm enough to start seedlings in the garden in late winter/early spring on Michigan. I don't have the space/money to make a big pile and get the pumps and pipe run.

author
beastcoast94 made it! (author)beastcoast942015-01-23

The heat output should be sufficient but you must be mindful of the gaseous anaerobic decomposition byproducts. Concentrations can become too high and kill plant life.

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josuchav made it! (author)2014-11-26

This is some cool stuff

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silgan.samirtnok made it! (author)2014-11-20

Hello, I have a quoestion here. What about rebuilding this system after these 18 months? Do you remove everything, like: hay bales, pipes? How do you do it?

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vladivastok made it! (author)2014-09-19

THANK'S 4 THE INFO. DO YOU KNOW IF COMPODT PILES NEED COVERING AT ALL , DURING THE WINTER MONTH'S? THANK'S [ VLAD ]

author
katrinaspade made it! (author)katrinaspade2014-11-03

Hi Vlad,

The hay bales act as an insulator to the piles inside. We found lots of nice heat being created even in the chilly NE winter. Next time, we might consider planting some kale on top of the mound, which I bet would do great as a cold season green.

Best,

Katrina

author
andrea.brugnolli made it! (author)2014-06-24

https://www.facebook.com/andrea.brugnolli/media_se...

facebook andrea brux brugnolli


ask friends

1506435_10202138812304213_855719596_n.jpg
author
dorybob made it! (author)2014-04-29

Great Instructable! Very good graphics. After digging through your information, did you use a Hobo Micro Station Data Logger - H21-002? With various Hobo sensors? How did you calculate BTUs? Temperature change x flow rate? I noted BTUs for other things in addition to the Mound. Thanks.

author
katrinaspade made it! (author)katrinaspade2014-05-22

I believe we did use a Hobo Data Logger - not sure of the actual item #. BTU calculation was flow x temp change, yes. On the flow chart we show the approximate BTU of all of the inputs, as well (hay, shredded wood, sawdust) so that we could get a sense of the total BTUs created (net inputs).

Best,

Katrina

author
dorybob made it! (author)dorybob2014-05-23

I have been reviewing the Hobo website and found much useful information. I have constructed a solar panel and would like to measure the BTU output to determine if it is worthwhile to build more panels. The Hobo data logger and sensors will be quite useful for this purpose. Thanks for the reply and good luck with the continuation of your project.

author
DANY.LIPSKER made it! (author)2014-04-29

EXCELLENT INSTRUCTABLE

WE LIVE IN A DRY AND HOT COUNTRY AND THE COMPOSTATION IS MAINLY MADE BY COVERING WITH A CLOSE AND NON PERMEABLE SHEETS FOR MONTHS, THUS NOT ALLOWING TO RENEW GARBAGE OR MORE MATERIALS TO ADD DURING THE PROCESS.

A REAL OUTPUT IS HEAT, BUT NEVER AT A STEADY PACE LIKE IT IS SHOWN HERE.

CAN YOU SHARE SOME OF YOUR EXPERIENCE FOR HOW TO ADAPT YOUR SYSTEM SO IT CAN OPERATE IN ARID AND DRY LOCATIONS LIKE OURS?

WARM REGARDS

author
katrinaspade made it! (author)katrinaspade2014-05-22

Hi Dany,

I am not sure about arid and dry locations, having lived mostly in New England and the Pacific Northwest. You might consider googling permaculture organizations in your area, as they would know best how to compost locally.

Best,

Katrina

author
DANY.LIPSKER made it! (author)DANY.LIPSKER2014-05-22

thanks anyway

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rippa700 made it! (author)2014-04-29

Looks great - I have often been tempted, but a couple of points. 1/ burying the HW pipe won't help much - you will heat soil rather than air. Best to insulate it. 2/ How doe syour heat output compare to all the fuel used to bale hay and shred trees? A lot of fuel in the making.... But I'm keen to try with a compost heap. Well done.

author
katrinaspade made it! (author)katrinaspade2014-05-22

Also, you are right re: burying water lines. The buried lines were also insulated...that said, we lost a lot of heat from mound to greenhouse. Closer is better.

author
katrinaspade made it! (author)katrinaspade2014-05-22

So true! We tried to give numbers to the hay and shredding, as well, in the BTU flow diagram. Still comes out on top, PLUS you're left with excellent soil building material. In fact, I like to think of this as a soil building machine, which happens to make heat as a by-product...

Best,

Katrina

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pauljeanquart made it! (author)2014-04-29

Hi, Noticed in the original Jean Pain Mound that a LOT of Water was used to saturate the wood chips during the mound's construction. Is it not necessary ? What temperature did your "DRY" mound achieve? For how long did it stay hot?

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katrinaspade made it! (author)katrinaspade2014-05-22

Hi!

You will see in the chart that we did indeed add water at a few critical points. This will "jump start" a dry mound. Moisture is indeed required.

best,

Katrina

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spikeseller made it! (author)2014-04-28

GREAT project! Did you chart BTU production vs time? How high was the spike?

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katrinaspade made it! (author)katrinaspade2014-04-28

We did chart BTU production vs time. Here is a short blog about our process:

http://decompoheat.tumblr.com/

And here's a chart of water temps and BTU production, from the first two months You'll see there were quite some ups and downs. Thanks for taking a look!

chart of results.jpg
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goatboy825 made it! (author)goatboy8252014-04-29

This is the best work I have seen in several years of study. I have shared this with Permies.Com and Permacultureglobal.com, Geoff Lawton and the Permaculture Supporter Linkedin Group.

Do you have any more data on the continued life-cycle of the experiment?

When I went to the tumblr site, I was surprised at how long this went on...

author
katrinaspade made it! (author)katrinaspade2014-05-22

Yes, we were surprised, too. The mound is now about three feet tall and full of really nice, rich, dark brown compost. And it's still warm, though we have stopped charting temps. I recommend going to the Compost Power Network, as they have some good information on this type of system as well.

Best,

Katrina

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jimmypat made it! (author)2014-04-29

Excellent Instructable! How did you make that energy flow diagram? It's fantastic!

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katrinaspade made it! (author)katrinaspade2014-05-22

Thanks, Jimmy. We made the flow diagram using Adobe Illustrator.

Best,

Katrina

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vladivastok made it! (author)2014-04-30

I DON'TLIVE WHERE I CAN PULL THAT OFF, FULL SCALE. MAYBE SMALLER.BUT I WILL. THANK'S [VLAD]

author
jwansitler made it! (author)2014-04-30

This is brilliant. Really great idea.

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codongolev made it! (author)2014-04-29

this is the kind of cool stuff I come to instructables to see.

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benwade made it! (author)2014-04-29

Am I right? I'm coming out with this being equal to about 42 gallons of oil?

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Biodynamic made it! (author)2014-04-29

Super job! I would love to try this at my school to heat our greenhouse. Thanks for sharing.

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goatboy825 made it! (author)2014-04-29

This is great. The DATA really helps make the case for doubters. I have posted this to Permies.Com as I think this goes across many forums.

Congratulations for making this so simple and with such great evidence.

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GreenMeUpScotty made it! (author)2014-04-29

Well Done Guys! Thank you for sharing and encouraging projects such as this.

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WouterZ made it! (author)2014-04-29

That's amazing guys... Wow

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fixfireleo made it! (author)2014-04-29

cool. why does the government spend TRILLIONS on "green energy" that never works when everyday people can come up with inexpensive, common sense, WORKABLE solutions?

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Vettel made it! (author)2014-04-29

WOW!!! Yes, please update us on how is it living now, what are the maintenance you do to keep it up? How productive was it recent winter>

THANKS!

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domestic_engineer made it! (author)2014-04-29

Nice job. I wonder if this would work on a smaller scale, like a regular sized compost bin. Only one way to find out. :)

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