Heating your house with compost!

[TheMitchells]

Hows this for an idea?  And as a compost heap does get very hot - why not? From Unwaste the Planet on FB....

 

 

Instead of burning wood for warmth, more and more people are turning to a clever, low-cost alternative: building a compost pile over coiled plastic water lines from the hardware store.

As the plant material decomposes, it naturally produces heat — reaching temperatures of up to 149°F (65°C).

With a simple circulating pump as the only moving part, this compost heating system is remarkably reliable, lasting on average 12 to 16 months and sometimes up to two years, while providing enough energy to heat a 1,500 sq. ft. home and supply up to 80% of its hot water.

[Gone West]

27 minutes ago, TheMitchells said:

Hows this for an idea?

I don't want to rain on your parade, but it would take me years to fill a compost bin that is, what looks like, over 2m high and 4m diameter. That's from my just over half an acre, sounds like a plan for the National Trust. Our compost bins rot down very quickly.

[marmic]

great idea - had I only thought sooner!   Whilst building we've been doing this in the shed:    https://humanurehandbook.com/   which would provide a constant free heat source and not take years to fill. And quite ok to use in a house too.   Not sure what BCO/EA would have to say and how to complete part L docs etc  - but could well be on the agenda to heat garden office when I finally get there - no regs!..............got to finish the house first though  

 

 

[torre]

2 hours ago, TheMitchells said:

more and more people

I don't think there are that many people with the plant, materials and experience to safely build a double garage size compost heap and a ready supply of half a m3 of compostables per week to feed it, presumably needing a digger to load efficiently, but I guess it points to being able to heat a garden room from something more manageably sized.

 

It'll produce most of its heat when you need it the least though (summer) and during the winter if you draw off too much heat from the compost won't you risk the whole system stalling?

[marmic]

if you draw off too much heat from the compost won't you risk the whole system stalling?

 

Good point!

[-rick-]

I think it's a fairly common option (in other countries) to use a compost pile to heat greenhouse during winter. Heating a house is a whole other level, maybe if you have a small farm.

[marmic]

also depends on performance of house - if energy requirements are ridiculously low it's quite possible.  time will tell but once we have completed our build (passivhaus) pretty sure the heating will rarely kick in.

 

[Marvin]

This is a subject I have researched and worked on in detail. The production of heat is caused by the bacteria reaching between 37 and 54 degrees centigrade with the right amount of oxygen and water. Far below 37 it just rots and takes ages. Far above 54 and it dries out and goes crispy.

 

In huge commercial trials this has been hard to duplicate for several reasons. Although you can calculate the heat potential, controlling it, is nigh on impossible.

 

Information, and my own trials, show that the mound needs to be at least 1 cubic meter and live material. Yes the compost goes better in summer but you can insulate around it in winter, but then it can over heat and the bacteria dies. Also it needs to be mixed correctly. 

 

 

[ToughButterCup]

Thanks very much @Marvin. I saw this thread and thought - Aha! A present for SWMBO for Christmas. The way I see it,  she produces more green stuff in one half acre garden than one person ought to be allowed to. And about double the waste material: every bloody year. She's like a whirling dervish. But we're having a large greenhouse built ..... Bettcha its going to be used as a garden office innit....

 

 

Where's @Ferdinand when you need him? As he says The Devil (or in his case God) is in the details 

Edited Thursday at 11:51 by ToughButterCup

[TheMitchells]

At a town near me, the council allow tree surgeons to dump all their tree waste on a waste site and anyone can go and help themselves to the bark.  I have used it quite a lot and when collecting it (a trailer load takes me about 20 mins to fill), the heat coming from the heap is amazing.  So I'd be okay, I'd just go and get a new load and keep replenishing the composter.  😄.  And bark is slow to decompose - should last quite a while.  

[-rick-]

17 minutes ago, TheMitchells said:

At a town near me, the council allow tree surgeons to dump all their tree waste on a waste site and anyone can go and help themselves to the bark.  I have used it quite a lot and when collecting it (a trailer load takes me about 20 mins to fill), the heat coming from the heap is amazing.  So I'd be okay, I'd just go and get a new load and keep replenishing the composter.  😄.  And bark is slow to decompose - should last quite a while.  

If you have the space AFAIK there are services you can sign up for that basically put you on a list and when a tree surgeon has a load they want to get rid of near you they will know to call and ask if you want it. Zero cost because they usually have to pay to dispose so its a benefit for them. Though obviously you need enough room to take a decent sized load of chippings.

[Ferdinand]

Good morning everyone.

@ToughButterCup for architecture it's "God is in the details" - that was your compatriot Ludwig Mies van der Rohe. This was perhaps after he ahd the details everso slightly wrong in the previous 20 projects in ways that no one else noticed, but drove him to distraction.

 

On the giant compost heap, I think it's a little low in energy density. I think this was one where one of those mad-scientist hippy types did some experiments in the 1990s with ginormous compost heaps like long barrows.

What would the emissions per kWh of heat be?

For me, it's in the same niche now as things like interseasonal heat storage and domestic wind turbines. Potentially of inerest in niche settings comprising about one house in 5,000 to one house in 100,000.

My recommended domestic alternative would be to have a sealed, insulated basement, a long-drop loo, and to eat lots of curry.

[Marvin]

46 minutes ago, Ferdinand said:

I think this was one where one of those mad-scientist hippy types did some experiments in the 1990s with ginormous compost heaps like long barrows.

Also there were industrial scale trials. But look at the big scale and the fact that they couldn't easily regulate the output.

 

https://www.pure.ed.ac.uk/ws/portalfiles/portal/8885379/Energy_from_Waste_Reuse_of_Compost_Heat_as_a_Source_of_Renewable_Energy.pdf

 

14 hours ago, TheMitchells said:

And bark is slow to decompose - should last quite a while.  

The mix to obtain the warm reaction needs to be live.  Mixing grass cutting, green (not evergreen) stuff and an amount of shredded sticks works quite well because of the mix of aeration, moisture and bacteria.

 

I expect to start a pile next week and will supply info. 

 

I only use this as a way to produce great compost of garden waste. (not vegetable waste either!)

Edited Friday at 08:37 by Marvin

[marmic]