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Compost Heat

Posted: Sat. Dec. 17, 2016 3:57 pm
by NoSmoke
This definitely fits the category of other, but I have researched and have been thinking for quite some time about this possibility...heating my home by compost heat.

I grew up on a farm, and while we tried everything in the world to stop silage from heating up and resulting in spoilage, in digging into the pile, inevitably it was quite warm almost to the point of putting your hand in it hurt...and this was the depth of winter! I always thought it was a waste of heat. It was not until I got sheep and a house that is fully radiant heated that I thought it might actually work.

My entire house is slab on grade with radiant heat with a PLC mixing valve system. It does not matter how the main boiler loop is provided heat...coal boiler, propane boiler, solar heat, or compost heat...as long as it is between 100-150 degrees the propane boiler won't come on. So with compost heat, I would simply be taking the heat composting in a pile and bring it into my house via pex tubing.

I think I got all the major components to do it. Since I live on a hill with a 6% grade, and I have a 53 foot insulated box trailer for a tractor trailer set up, I would make a cut in my hillside, burying it into the ground with all but the back end covered. I would fortify the roof, then cover that too with soil. That would insulate the trailer quite well. Then I would loop the roof of the trailer with pex tubing probably pretty tightly, like 6 inches on center. That would then be piped to the main boiler loop with a big circulator to pump the water. The trailer body would then be charged with a mixture of waste silage/sheep manure/and wood chips to get a "hot compost" in the fall of the year. As the heat from the composting action rose, it would heat the water in the pex and be transferred to my concrete slab in my house.

Since the cost would only be for the pex (1000 feet), a big circulator, and to dig a hole deep enough for the trailer, I wonder if it would not be worth it?

Re: Compost Heat

Posted: Sat. Dec. 17, 2016 4:21 pm
by franco b
Some years ago Mother Earth News had an article about a Frenchman who was heating his house with a compost pile with copper tubes run through it.

You might see if they have other information.

Re: Compost Heat

Posted: Sat. Dec. 17, 2016 4:31 pm
by grumpy

Re: Compost Heat

Posted: Sat. Dec. 17, 2016 5:19 pm
by freetown fred
In VT. I had a spring that fed my house on a hill, damn, seems like I always end up on a hill of some sort. Anyway, all ledge for the 75 yd run--started w/ 1" blk. plastic, reduced to 3/4" entered house at 1/2"-- could only get down about an inch or less--I put 6-8 inches of cow sht over the whole run & in 12 yrs, NEVER had it freeze up. Yep, that "compost" stuff is kinda like duct tape, good for what ails ya!!!! :clap: toothy

Re: Compost Heat

Posted: Sat. Dec. 17, 2016 5:55 pm
by samhill
Years ago a friends farm that was fed by a stream would freeze up once or twice a winter, since we knew pretty much where the spring ran we would spread horse manure over top & in an hour or two the water would run just fine. :)

Re: Compost Heat

Posted: Sat. Dec. 17, 2016 10:32 pm
by CoalisCoolxWarm
I've looked at that in study with great interest, including the Mother Earth articles, students who buried black barrels in compost (way too hot), but here is my favorite use.

http://www.lowtechmagazine.com/2015/12/reinventing-the-greenhouse.html

Understanding compost and its uses is quite interesting.

Too bad the EPA is working on sewing up the compost producing end of livestock to prevent CO2 instead of planting green plants and trees to balance the CO2 in the environment :shock: LOL

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 7:52 am
by titleist1
Would there be any danger with the gas build up in the trailer? Not necessarily for explosion reasons but if you enter it without ventilating adequately could it kill you? This has happened to more than a few farm workers but I don't know the details of the manure pit they were working in.

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 10:25 am
by CapeCoaler
compost would need air...
Or it will be a septic tank...
anaerobic lack of free oxygen...
This is what makes a stinky compost pile...
aerobic is what a non stinky true compost pile is...
Build it big enough with the ability to breath...
Without turning the pile over...
and you can lay your pipes in the pile...
Stage the piles and you will have heat all winter...
Proper carbon to nitrogen ratio and you are good to go...

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 10:57 am
by titleist1
CapeCoaler wrote:Build it big enough with the ability to breath...
Without turning the pile over...
Any ideas on how you get this to happen....use perforated pipe through the pile to allow air flow? Maybe the opposite would then happen, the methane would be piped out of the pile rather than air into the pile??!! Then you just hook up your methane pipe to the burner - just kidding!

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 11:28 am
by CoalisCoolxWarm
In chicken coops, we use something called "Deep litter method"

In essence, after a good layer of manure, add diatomaceous earth and a good layer of dried wood chips for carbon content.

It keeps the ammonia from building up and makes a very nice compost result...in place. We do an annual cleanout over to the outside compost pile to store and finish.

Lots of good info about composting if you google that topic. Should be helpful

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 3:33 pm
by NoSmoke
No need to aerate the pile, there is enough trapped air within to get the pile to cook. We use special ($12,000) packers for the silage pile to exclude air and while we are getting excellent compression, it still heats up.

I wish my idea was novel, but there is a guy doing something similar, but I am not sure how big of an area he is heating. Jean Pain required 55 ton piles for 6 month burn times, but my pile would only be around 18 tons. However with no pipes to mess with, I could renew the compost all winter. I got a hundred sheep that keep adding to the pile every day. That was what I liked about the trailer idea; the pex tubing was permanent.

As a side note, after yesterdays -10 below zero weather with 45 mph winds, (-44 below windchill), the water line to my barn froze up. I know where the weak point is and while it thawed out today, I took your suggestions and dumped two big bucketfuls of sheep manure over the pipe and will let you know how it does this winter.

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 3:39 pm
by NoSmoke
One crazy idea I thought of, is using the long term heat of compost, and a Stirling Engine, to obtain electricity. Since a Stirling engine is a low heat engine, and operates on the difference between its hot and cold side, you could use the compost pile for its heat side, and run pex tubing through the ground (below 4 feet) for the cool side to get the required differential.

A company is using a greenhouse to provide low heat for a Stirling Engine and producing power, BUT it is limited to daylight hours. A compost pile would power a Stirling Engine 24/7 which would provide a substantial amount of KWs, and lower the return on investment. But building a working Stirling Engine of enough size to power even a modest 3 KW jenny might be an issue.

http://www.solarheatengines.com/2012/01/10/tamera-video-of-sunvention-sunpulse-engine/

Re: Compost Heat

Posted: Sun. Dec. 18, 2016 4:36 pm
by CoalisCoolxWarm
If outdoors, consider adding sawdust to make up volume with manure.

You will want to stick a few temp sensors in the pile.

Compost piles can and sometimes do burn. Just be careful how you monitor, manage, and locate piles ;)

Re: Compost Heat

Posted: Thu. Mar. 28, 2019 8:21 am
by keegs
CoalisCoolxWarm wrote:
Sun. Dec. 18, 2016 4:36 pm
If outdoors, consider adding sawdust to make up volume with manure.

You will want to stick a few temp sensors in the pile.

Compost piles can and sometimes do burn. Just be careful how you monitor, manage, and locate piles ;)
I imagine with the right skills one could keep a compost as a source of fuel. Kind of like burning coal in slow motion :) . I imagine there're various system designs out there that describe the kinds of kit you need....Horse manure added to my garden compost kicks up the heat for sure. I think maintaining a certain moisture percentage can dampen combustion. It's an interesting idea for those who have the space and available inputs.