[Digestion] Woody Biomass digestion via compost

Sat Dec 2 15:30:36 CST 2006

I live in the PNW also, and I'm wondering why not simply burn the woody 
material? Boilers and stoves are very efficient nowadays, and AD doesn't 
extract all of the energy from the feedstocks. In fact, even the energy that 
AD does extract is pretty inefficient, since a fair amount of the carbon in 
the feedstocks is turned into CO2 in addition to the methane. In burning, of 
course, virtually all of the chemical energy in the carbon is converted to 
heat energy, and with some types of wood (such as used in pellet stoves) 
there is very little ash.

I'm a biologist who has done a little (very little) professional work on 
composting and ensilagement, and I can tell you that if the pile is large 
enough, it produces heat for a long time. There's a large abandoned corn 
silage bunker (basically a big AD unit) near where I live, and it's still 
 >120 degrees two years after the last material was added. I haven't had the 
chance to read much about it, but maybe what Jean Pain was doing was making 
a very large pile in the fall, then dealing with turning it in the spring.

Steve Verhey
Ellensburg, WA USA

>From: "Art Krenzel" <phoenix98604 at msn.com>
>To: "Wake Robin Design WRD" 
><wakerobinlandscaping at yahoo.com>,<digestion at listserv.repp.org>
>Subject: Re: [Digestion] Woody Biomass digestion via compost
>Date: Sat, 2 Dec 2006 11:14:08 -0800
>
>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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>
>
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