[Digestion] Woody Biomass digestion via compost

[Art Krenzel]

Abel,

I have been sitting here waiting for someone else to join in the discussion 
on Jean Pain's work but that does not appear to be in the wings.

I live in the Pacific Northwest and, yes, there are good chipper/shredders 
here.  I would look at my fuel requirements before I bought because there 
are chippers and there are shredders but few chipper shredders.  If you plan 
to move the fuel in some mechanized manner or have it flow in any way - 
chippers are the better answer answer.  If you want to make big pieces of 
wood into little pieces which do not have to be hauled or fed in any way - 
shredders work pretty good.  Middle ground is hard to find.

We have people on this listserve with more years of wood size reduction 
experience than I have who can comment on these items.

I would like to comment on the composting part of Jean Pain's experiment.  I 
have been making compost for a few years now and find it difficult to 
maintain high rate aerobic composting without having the turn or mix the 
pile several times after the initial surge of decomposition.  To extract 
sufficient energy to heat a house and provide for hot water needs as well, 
any compost pile would need to be turned several times and/or new materials 
need to be added for all the time you would be extracting the energy. 
Nicolas Poulain's trip report presents an idyllic lifestyle of free energy 
and no work.  For those of us who have been on the front line of 
composting - that image is a bald faced lie.  Active aerobic composting is 
an energy intensive process!  This is especially true if you only use human 
power.  They say that wood is a fuel that heats twice - once when you cut 
and split it and then when your burn it.  Composting heats more times than 
that because you need to turn it several times to keep the reactivity 
sufficiently high to be able to extract heat energy.

Composting is great but high rate aerobic composting is not idyllic.  Biogas 
is great but works best with soluble oils and food grade feedstocks - not 
wood shavings or wood chips.

Does any of this make sense to anyone?  Has anyone out there had a garden? 
The pictures show that you just need to plant the seeds and then there is 
harvest.  It does not show the weeding, watering, staking, pruning, etc that 
goes on between those two endpoints.  A large garden can eat YOUR lunch. 
There is only so much time in a day and you have to make the best use of it 
if you want to survive to see tomorrow especially where hand labor is 
involved.

As I said, I live in the Pacific Northwest and would like to discuss small 
scale sustainability with you but we need some ground rules as to size, 
support and feedstocks involved.

Art Krenzel


----- Original Message ----- 
From: "Wake Robin Design WRD" <wakerobinlandscaping at yahoo.com>
To: <digestion at listserv.repp.org>
Sent: Sunday, November 26, 2006 6:47 PM
Subject: [Digestion] Woody Biomass digestion via compost


> Greetings,
>  I was wondering if any readers have come across the work of Jean Pain. 
> The man who converted overgrown hardwood forests in southern france into 
> healthy woodlands while simultaneously producing methane, methanol, hot 
> water, and compost from the digestion process?  I am trying to track down 
> his book or a book on the subject which illuminates the specifics of this 
> method.
>
>  What I understand is that instead of creating a slurry, he built piles of 
> wood shavings saturated by water.  I am guessing that by composting the 
> debris he was able to heat the inside of the pile enough to produce 
> methane.  It seems like a simpler approach than heating a tank filled with 
> a slurry.  Does this seem possible?
>
>  I want to eventually apply this method in the Pacific Northwest region of 
> the USA.  What is the feasability of using wood shavings from northwest 
> connifers like douglas fir and western red cedar?  Does anyone have any 
> specifics on the amount of energy produced per ton using this particular 
> material?  How hot do you need to keep it?  Does the collection energy 
> justify the energy retrieved by digestion?
>
>  I am also interested in learning more about the way gas is collected from 
> a compost pile.  This particular bit of information has not been revealed 
> by any articles on Pain
>
>  Finally, any ideas on some good chipper shredders in the PNW?
>
>  If anyone has any thoughts on any of these questions I would be grateful,
>
>  Abel Kloster
>
>
>
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