# Btu comparison



## fishhead (Jul 19, 2006)

Can anyone tell me if the Btu's released during combustion of 1 lb of wood chips are equal to the Btu's released during decomposition of a 1 lb reduction of wood chips?

Decomposition won't use up as much as combustion so I'm trying to compare a 1 lb reduction by both methods.


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## Bearfootfarm (Jul 13, 2006)

The Btu output will be less with decomp vs burning since, as you stated burning is more complete (efficient)

The decomp will produce lower temperatures, but produce it's heat over a longer period of time, and you will still have compost as a usable by-product instead of just ashes.


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## fishhead (Jul 19, 2006)

I just saw some wood chip piles steaming away and it restarted my curiosity about using a wood chip or sawdust pile to heat my home and water.

If decomposition produces even 1/2 of the Btu's that combustion does it should work fine.


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## Bearfootfarm (Jul 13, 2006)

It's going to take *tons* of chips and sawdust to generate enough heat to do any good.

This guy *claims* he can get 18 months of heat with this system, but I'd have to see it to believe it. 

It's not just a simple matter of dumping a pile of material somewhere.

http://www.instructables.com/id/Compost-Heating-System/?ALLSTEPS

Also note he says this will heat a hot tub or a greenhouse, but doesn't mention heating a home. He claims it produced *6 million BTU's* over 12 months

This site says it take over *27 million* per year just to heat water for a family of four, and *70 million* per year to heat the home:

http://www.skidmore.edu/~jthomas/lifestyleproject/btuusagecharts.html


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## fishhead (Jul 19, 2006)

Yes it does take a large mass of chips or sawdust to produce the heat needed. That's understood.

I've seen large sawdust piles that were too hot to dig into with bare hands after more than 20 years.


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