Compost Heat

[Streetwise]

I am thinking about ways to keep a tub outdoors year-round in a cold climate. How much heat can a compost pile generate to keep a tub warm?

[Koi]

Don't have an answer to your question but I wanted to ask how you were gonna use the compost pile. Was is supposed to be a form of insulation?

Not sure if digging is an option but my pond stays pretty insulated just from ground temp. Some kind of black lid will absorb heat from the sun and trap it into your tub too. Or glass/plastic lid with a shade cloth on top

[Streetwise]

@Koi, I am just brainstorming. I keep tubs and a tank at my folks' house, and they have a compost pile in the woods.

[Koi]

You're gonna have to walk me through this, I feel really dumb right now haha. 

42 minutes ago, Streetwise said:

How much heat can a compost pile generate to keep a tub warm?

 Could you elaborate on this? I'm a little perplexed by the question

[Hobbit]

If you don’t constantly stir it (like every day) then it will stay pretty cold. We have a compost pile that we never turn but our chickens spread out on a regular basis (and then we re-pile it. According to the bits of snow we’ve been getting, it doesn’t stay any warmer than the ground around it.

I’ve also heard you can get them much hotter by adding lye. But no matter what, it won’t get very hot on its own.

[Streetwise]

I ran three tubs outdoors in Vermont weather last summer, with White Clouds and Neocaridina. As I understand it, these species can survive under ice. I would like to try to run a year-round setup. I could probably do it with farm heaters, but this forum is full of of clever ideas, and composting seems to be a good source of heat, which would align with my substrate choices.

Edited February 13, 2021 by Streetwise

[Koi]

Ok ok I get it thats what I thought you were talking about. For some reason when i reread "generate heat" it sounded like you were gonna light stuff on fire haha

[TheDukeAnumber1]

My encounter with using compose for heat is we bought a very old farm house that had a pump house with an above ground well pump. It was evident that at one time there was hay or straw placed around the pump and pipes to both insulate and generate heat with apparent success as the pump was super old. We have since replaced with an in well pump though.

My other thought is that I have a Chicago hardy fig tree, which if I want to not die back to the ground in my area I am supposed to tie up the branches and wrap it in plastic and fill it with leaves as I go. The leaves are supposed to insulate and generate heat I have not tried this yet as other projects keep getting in the way atm.

I know this probably isn't super helpful info but maybe it can spark an idea. I'm hoping to do a year round tub too but after watching a live stream the idea was that if your furnace exaust is in a spot where you can put a pond close by that that could be enough to keep it from freezing, and my exaust is in a pretty good spot. Hope this helps.

[Brandy]

I had a long thermometer for just this purpose a number of years ago. As I recall a properly built compost pile about a cubic yard in volume could reach a good 50 degF above ambient temp--right in the middle, for about a week at most, at which point you need to turn it to renew the activity.

We did sometimes use it to start seeds in a cold frame, doubling up the compost heat with solar gain to speed germination, but without ready access to a hot manure pile and a lot of shoveling I think it would be hard to use it to sustain heat thru a northern winter. What might be a simpler and more effective solution would be an insulated cover and sinking them in ground. How deep does the ground freeze at your folks place in the winter? I am in the PNW and our winters are candy by comparison, but a 5 gallon bucket full of carrots and beets in the ground with a flake of hay laid over the top would keep carrots and beets from freezing solid here. I would trust that approach more.

[Streetwise]

@TheDukeAnumber1, @Brandy,  @Koi, @Hobbit, thanks for the feedback. I like exploring the idea of year-round tubs. It looks like Vermont just gets too cold for compost heat to make any difference with small tubs, but warmer regions might benefit. I appreciate the consideration. Please keep the conversation going.

Edited February 13, 2021 by Streetwise

[gardenman]

Old school gardeners would let grass grow long before that first spring mowing, then layer the cut grass and whatever manure was handy and bury it in a trench and give it a few days for the decomposition to warm the soil and then plant crops that love warmer soil temps above the trench. They could gain a few weeks to a month of more of growing time by this method. This technique both added heat and organic matter to the soil. Native Americans would plant corn with a non-food fish. The decomposing fish would provide both nutrients and heat to the soil around the seed and ensure a good crop.  Burying a tub in the middle of a compost bin could work, but would be challenging. It's easier to simply build a PVC pipe hoop house type greenhouse over the tubs. That alone should keep the tubs from freezing solid as long as you get some decent sunlight. Barbara Damrosch and Eliot Coleman use hoop houses in Maine to garden pretty much year round.

[MJV Aquatics]

As a somewhat former organic gardener I did a lot of composting and vermicomposting. Properly built (greens and carbon) and watered compost heaps will initially yield a temperature of up to 160°F, but will cool and reheat after turning...but in time the thermal bacteria are done and the pile cools to ambient. You might better look for ways to heat, then insulate the tubs. The tricky part outdoors is also keeping the insulating material dry.

I have a 110g stock tank in my unheated basement (55°F in winter). I used a double wrap of carpet padding to act like a koosie. You might use styrofoam and/or straw/hay bails for insulation...or bury bins/tubs in the ground?

 

[Will Billy]

If i am following your thought train in the right direction... a highly agitated and well manicured compost pile of 1 cubic yard (3 feet by 3 feet) produces internal temperatures of around 140F. But that is the internal temperature, and once the microbiome has completed it’s job the temperature will begin to level off. I like the idea of MJV aquatics adding insulation to help retain the heat, and it got me thinking out loud about composting inside a green house. Combination of heat + insulation + green house, may have a greater effect. A couple of issues with composting inside of a green house that come to mind is #1 the odor, #2 are the off gases trapped inside safe, #3 composting uses oxygen, so transfer of oxygenated air inside confined space would be required. I dunno, like i said i was just thinking out loud. I like where you are going with the idea tho.