Author Topic: Heating your home with mulch?  (Read 10683 times)

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Titantornado

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Heating your home with mulch?
« on: October 25, 2006, 11:03:27 AM »
So, driving by a mulch company, and seeing piles of steaming mulch, I wondered to myself if there isn't some useable energy there.  You've probably heard stories of mulch piles occasionally spontaniously combusting from their own heat generated by the decomposition of it's own materials.


Well, what if someone were to put some Pex tubing runs within the pile and extract that heat?   I'm not sure how hot it gets, or how much you'd need, but it seems like a working concept.  Of course the pile wouldn't last forever, eventually the decomposition would slow and heat would reduce, but I imagine you could get a few months out of it, perhaps make it through the Winter.  The extraction of heat might even regulate the rate of decomposition too.


Also, I would imagine the greener the material, the longer and more BTU's could be extracted.  I wonder about the mulch company's piles.  Their stuff is always that rich brown color already.  I wonder why you don't see mulch that's greener in appearance.


Anyhow, once you've extracted all the heat available, in the Spring, you could then use it for gardening, and sell off the excess.


Thoughts?

« Last Edit: October 25, 2006, 11:03:27 AM by (unknown) »

wdyasq

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Re: Heating your home with mulch?
« Reply #1 on: October 25, 2006, 05:35:20 AM »
Large piles of mulch can hit 140-160F. This has been done in commercial operations. I'm not sure what size it becomes practical. Mulch piles should be 'turned' occationally to evenly mature. Pulling too much heat will cause the process to slow or stop as the bacteria work better at certain temperatures.


Ron

« Last Edit: October 25, 2006, 05:35:20 AM by wdyasq »
"I like the Honey, but kill the bees"

nothing to lose

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Re: Heating your home with mulch?
« Reply #2 on: October 25, 2006, 06:49:26 AM »
Yes it could work. Actaully several ways. May be some old posts about it here also.

 Another thing I have built smaller scale for testing but never built the full sized unit yet.


 For alot of things, like leaves, you can let them dry naturally and just burn them in the wood burner. Most leaves burn clean as wood, fast and hot, when dried. People burn them fresh and wet in the fall when they rake them up and it's a nasty smokey fire that way. For fast heat to just take a chill off the house when a big long lasting fire is not needed I use leaves sometimes. Also old paper bags, old boxes, and junk mail. I don't do much for composting yet, though I do have acres of leaves I could use.


Well back to the composting,


"The extraction of heat might even regulate the rate of decomposition too."


OR it could stop or slow decomposition to an unuseable rate if your not carefull.

At one time I knew what the temps get up to inside those piles at times but forget now, maybe 190F or somewhere around that, perhaps it was alot more. Sawdust piles catch fire in Texas paper mills sometimes because of internal decomposition heat and hot summer sun. Been there, seen it.


Human waste and animal waste, dodo, crap, or whatever you prefer to call the stuff gets hot enough to kill the pathogens also in a proper pile, container etc..


Now, the same organic wastes also produce methane gas while decomposition takes place!

So rather you use leaves and grass clippings for a cleaner pile, or include dodo also it will do the same thing, safer for health without the dodo if you make mistakes or use mulch for food type plants.


Decomposition in the pile needs 3 things to complete properly. Heat which it makes itself, moisture which it normally contains, and air/oxygen which it uses up and needs replaced. The replacement of air/oxygen is why you hear people say a compost pile needs turned every so often, basically stirring in more air. Also to move the outer surface to the inner part of the pile, but mostly for air.


Now if you just toss a pile in the yard you will lose alot of heat to the air when you most want it depending on your inviroment, winter! It may even freeze solid in colder climates.


I used some 55gal barrels with removable lids, sealed well, tubing mounted to top for gas. Methane can be gained and used in a burner or to run a generator etc.. if done right and large enough system. I did different things with mine diffent times. I got some nice gas over time but not very fast, but that was a very small system.


If a nice big insulated box is built, maybe even add some solar heating, you could get lots of nice hot water or such from internal tubing in the pile. Make an easy way to turn the pile without tangling up the tubing. If the unit is sealed well you could even figure a way to extract the methane gas for some type of burner. At times you will have to add more air and stir the pile to keep the system working, how often would depend on many things, maybe once a month or once in several months.


Some foriegn countries in rural areas use the methane produced from septic type systems , you get the same gas from compost.


If your using clean stuff like leaves, grass, etc.. and don't care how long the pile takes you could set up a system as a preheater for your hot water tank year round. Just make sure the pipes won't freeze in winter and bust.


Perhaps use an old water tank in the supplie line, tap into the lower section with the piles tubing coil, and back into the tank at the upper secton. Let the pile heat the water in the coil and convection circulate it to the tank. The longer the water sits in the tank the warmer/hotter it gets. Could be a good preheater for solar water heating or after the solar heating system. If using convection to flow the water through the pile then the water tank should always have the hottest water, no reason for it to cool the solar heated water.


I forgot about it, but I was going to try heating the pumphouse this winter with several barrels of compost, tubing, a radiator, and convection flow.

Place the barrels on the sun side of the pumphouse in a box, radiator in the pumphouse. Put a thermostat on the light I normally use for heat to turn it on about 28F and see if it ever comes on this year. Got busy with other stuff and forgot about  building it :(

« Last Edit: October 25, 2006, 06:49:26 AM by nothing to lose »

Slingshot

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Re: Heating your home with mulch?
« Reply #3 on: October 25, 2006, 08:50:59 AM »
My guess would be that not a lot of heat could be extracted from a typical mulch pile.  


If everything in the pile were completely burned in some sort of furnace, that's probably the max heat energy that could be practically extracted.  Anything gotten from the same material during decomposition would probably be less, because only a fraction of the mass is actually consumed/oxidized.  


I'd think the max output could be estimated by taking the difference in dry weight before and after composting, and thinking about how long you could heat your house by burning that equivalent weight in a furnace.

« Last Edit: October 25, 2006, 08:50:59 AM by Slingshot »

tjspears

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Re: Heating your home with mulch?
« Reply #4 on: October 25, 2006, 11:15:00 AM »
One of the local Portland home owners on the rainwater collection group, did something similar, providing domestic hot watter and heat for the green house.


http://ersson.sustainabilitylane.com/greenhse.htm


--james.

« Last Edit: October 25, 2006, 11:15:00 AM by tjspears »

nothing to lose

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Re: Heating your home with mulch?
« Reply #5 on: October 25, 2006, 06:25:56 PM »
Maybe your correct, at least with the typical size open pile. But there is a good deal of heat ,and some methane if you use it, to be had in composting.


A big difference in composting for the heat and burning the matter for heat. If you burn it you must vent it, any type of normal chiminey and you will probably lose alot of heat up the stack. Only real by product is ashes to throw away. Well for most people, I sometimes use mine for things also but not all of it.


If you compost and get heat and also the usable gas for more heat, you still end up with compost as the byproduct which is also usable or sellable. Saves money on vertalizing plants making your own instead of buying it. Either better food to eat, or better food to sell for better money, if you garden with it for food that is.

If you sell the compost, well you still offset what you paid for other means of heating  and use less other methodes of heating equal to any heat you gained from the composting.


If I were planning a garden I would rather try the compost methode for heating also instead of burning. Even if total heat output is less than burning, with composting you have several gains depending how you do it.


I don't garden (though I should) because I don't stay home enough and busy with other stuff etc... So I do burn the leaves in the wood burner sometimes as I mentioned before. Lots of good heat but only ash left over. Can only use so much ash, and never found anyone to sell it to yet, though I have not really tried to find anyone :)

« Last Edit: October 25, 2006, 06:25:56 PM by nothing to lose »

scottsAI

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Re: Heating your home with mulch?
« Reply #6 on: October 25, 2006, 08:35:05 PM »
Hi Titantornado,


Mother Earth News has many article on this subject. Search on; compost.

Three links showing it works, bunch to learn: Lots of different advice.


http://www.motherearthnews.com/Green_Home_Building/1980_May_June/Update_Mother_s_Compost_Heat_Experi
ments


http://www.motherearthnews.com/Homesteading_and_Self_Reliance/1980_September_October/Update_IIMoth
er_s_Compost_Heater


http://www.motherearthnews.com/Alternative_Energy/1981_July_August/Compost_Heated_Water


Have fun,

Scott.

« Last Edit: October 25, 2006, 08:35:05 PM by scottsAI »

Darren73

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Re: Heating your home with mulch?
« Reply #7 on: October 26, 2006, 01:03:47 AM »
NTL,

The decomposition in a compost or mulch pile is anaerobic not aerobic, ie without air, turning the pile ensures the material is mixed and composted evenly and cools the pile so it is less likely to combust.


with your sealed barrels, roll them around the yard once in a while to mix the material, this does not cause air to be included and will allow for the anaerobic bacteria to work more efficiently.


regards

Darren

« Last Edit: October 26, 2006, 01:03:47 AM by Darren73 »

gale

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Re: Heating your home with mulch?
« Reply #8 on: October 26, 2006, 04:31:25 AM »
There has been many experiments and actually the USDA has plans for a compost heated green house.  The key being the compost part.  The composting part turns that material up to a near steam generating temperature.  a poor compost pile will rise to 140-150F while a well built and turned compost pile can easily rise to over 170F-180F.  These temperatures easily rival the heat produced by a solar collection unit.

    The major problem would be regulation and length heat production.  While a compost pile will immediatly heat up and continue to heat for a month or more, that is still well short of the 4 months needed for winter.  and while waste organic material is readily availabe during the fall, the availability would fall short during the Jan and Feb monthes.

    One solution is just mass.  make a big pile, composting would slow and the mass would hold the heat.  A ensilage pile on dairy farms will freeeze on the surface, but the center would remain toasty.  Saying all of that, you probaly need a pile about the size of the house you wanted to heat.  The placement of tubes through that pile would hinder it's eventual removal.  Then there is the visual efect of having a large pile of compost next to your house.

    If you owned the mulch company, it would be a easy solution to heat your house, but otherwise....
« Last Edit: October 26, 2006, 04:31:25 AM by gale »

nothing to lose

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Re: Heating your home with mulch?
« Reply #9 on: October 26, 2006, 11:37:29 PM »
One solution for lack of waste organic material durring winter might be to make several piles in series. Cool the first few piles too much to slow the composting and preheat water, use the last big pile to bring the preheated water to full tempature.

When the last pile is nearly done and stops heating properly, load up a less composted pile, or just change water flow to alough the second to last pile to begin full composting and produce more heat.


Just piling up  some stuff in the back yard may not work so well and have problems with piping and turning. A chamber system properly built for the purpose could be designed. Maybe something like several chambers above each other. Load top and compost it, a built in shaker could later break up the pile and let it fall through a door into the second chamber and turn it at same time, load fresh materail in top chamber.

Bottom chamber could just be used for collecting the finished compost, no pipes and would be easy to remove the compost from it. A farmer or such could simply load to top chamber with his frontend loader. A conveyer or auger system could load the top also for those without a frontend loader.


I have 12acres of woods, I think I could make it through several winters without worring about lack of leaves. I have leaves from a few years ago still out there under fresher leaves from last year and this year. Naturally composting slowly I am sure, but still years of leaves piled up still usable. Course in MO. with our milder winters I could collect leaves most the time, people with months of 3' snow could not.


With a nice piece of equipment it would be no harder to collect tons of leaves than mowing a yard or brush hogging a field, bailing hay etc..

Comparing costs to collect it, money saved on heating, free gardening/farming mulch (or a sellable product), I think composting could be very wortwhile for some people or businesses.


The timber people around here and many other places work year round, they just leave all the branches lay and rot no matter how big. Sometimes some-one else comes along and cuts them for fire wood, most of the time they just lay there in a mess. Those could all be chipped up for mulch to compost. The portable saw mills leave big nasty sawdust piles behind to rot also. So the people with timber, company owners or employees, and saw mill people too could have year round fresh supplies.

Any saw mill around here has giant piles of sawdust, fresh year round. I don't know if costs would be worthwhile, but I could have dumptruck loads anytime and all of it I want. Might cost more than it's worth, might not? Some mills are glad to give away all they can just to get rid of it because it's a problem for them, some just burn up the piles, some want to sell it instead of giving it away.


Most of the problems can be figured out, and it could be very worthwhile for alot of people though not everyone.

For instance, firewood can be sold for more than sawdust. So any lumber mill that converts to compost heat could burn less firewood themselfs, thus have more wood to sell for more profits. Compost might sell for more than sawdust and certainly more than ashes, so with compost heating they would be making a sellable product instead of burning posible profits. Even though heating may not be needed in spring/summer/fall, the water system could be shut off and drained and they could still compost year round with the same unit if they wanted to.


 Hey, I think I just convinced myself to build one this winter here!!!

I have too many things to do already, but some of those can wait I geuss :)


Another advantage of a working compost heat system would be lack of involvement. A problem I have with wood heat is if we go away for a week or so in winter the house freezes from no heat or else I have to run very costly electric heaters. My kid lost alot of nice water globes one year when the house froze up!

A working compost system would not care if we were home or not, it will just always produce the heat just like electric or propane but without the costs.

« Last Edit: October 26, 2006, 11:37:29 PM by nothing to lose »

Kwazai

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Re: Heating your home with mulch?
« Reply #10 on: October 27, 2006, 06:30:47 AM »
hadn't posted in a while.

The last thing on Mother earth news site(compost heat) I read called for a 12ft diameter 4ft deep pile with the proper mix(25 to 1 cn ratio) of manure and grass clippings/leaves/(brown stuff). I always wondered if nitrogen based fertilizer could be substituted for the manure. The bulk of the pile size was for insulation value.

I'd read some stuff on hay bale fires(moist bales catch fire) which mentioned the 4ft dimension as the critical dimension there too.


http://www.motherearthnews.com/index.php?do=googlesearch&sitesearch=www.motherearthnews.com&
domains=www.motherearthnews.com&q=compost+heat&client=pub-7979199038709626&forid=1&c
hannel=8376782865&ie=ISO-8859-1&oe=ISO-8859-1&flav=0001&sig=yu5zOh57jjn9oUHT&cof
=GALT%3A%23008000%3BGL%3A1%3BDIV%3A%23336699%3BVLC%3A663399%3BAH%3Acenter%3BBGC%3AFFFFFF%3BLBGC%3AFF
FFFF%3BALC%3A0000FF%3BLC%3A0000FF%3BT%3A000000%3BGFNT%3A0000FF%3BGIMP%3A0000FF%3BLH%3A50%3BLW%3A389%
3BL%3Ahttp%3A%2F%2Fwww.motherearthnews.com%2Fgraphics%2Fcleanx50.gif%3BS%3Ahttp%3A%2F%2Fwww.motherea
rthnews.com%3BFORID%3A11&hl=en&sa=Search


fyi

Mike

« Last Edit: October 27, 2006, 06:30:47 AM by Kwazai »

gale

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Re: Heating your home with mulch?
« Reply #11 on: November 03, 2006, 07:37:53 AM »
The interesting about that article, is that the Mother Earth news group used only 5 tons, it lasted 9 weeks,the french man used 100 tons and it lasted 9 monthes.  Like I said above to have heat last all the way through winter, the pile had to be about as big as the house.


The use of manure was as a organic and moisture source, using chemical fertilizer would do almmost nothing, the compost pile did not need increases in the NPK levels to work, The bacteria involved has almost zero need for the NPor K.


As a former farmer, who baled many many bales of hay, spontaneous combustion of hay happens as out of control composting of hay.  From my personal experiences and observations.  Any hay baled too wet or wet and too tight, the bale will "heat" or basicaly compost.  You create a environment that is moist with limited air, perfect for a bacteria.  to get full blown combustion, generally you need another step.  My personal observation that the only hay I have ever seen hay combust has been when the hay was rained on significantly at least once. Most grass and alalfa have a natural wax on it's surface, I believe the rain washes of most of this wax.  Then the hay is baled too wet or the hay is mostly dry with clumps of wetness.  The hay then is stacked in tight pile or in area of limited ventialtion.  The "heating" takes place, but it is accelerated and heat is unable to leave, the temperature builds and builds and anywhere from 2 days to 1 week the hay finaly catches fire.  I have seen one round bale of hay catch fire in the same way in about 1 week.  The size of the bale was also 5' by 5' and very tightly rolled.  Not scientific, just my personal observations.

« Last Edit: November 03, 2006, 07:37:53 AM by gale »