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permaculture - Re: [permaculture] Interesting insight on biofuels

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  • From: Marimike6@cs.com
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Interesting insight on biofuels
  • Date: Mon, 3 Jan 2005 07:57:00 EST

Doug and Lora--

Manure effluent does contain a lot of CO2, plus traces of other gases. A good
overview and assay can be found here:

http://www.eere.energy.gov/consumerinfo/factsheets/ab5.html

I think the basic point to most collection-digester systems is that by
containing the manure for a period, usually around twenty days, you capture
the
gases that usually escape into the air, making your animal operation possibly
obnoxious to your neighbors or to yourself.

A sensible approach, if you're thinking of building one yourself, is to start
with a solids separator-- a sieve or slat system that will allow the urine to
be collected separately. I would just batch the manure itself into the
digester. If you have large amounts of rotten vegetables, like unsold
pumpkins,
lying around you can use them. But don't bother to put straw or grass
clippings
in. They have very little potential for outgassing, and have better uses
around
the farm.

Depending on the size of your operation, you can collect and pipe enough for
your cooking needs, and possibly for heating your water. But if you want to
heat a Wisconsin farmhouse in winter, I think you'll need a lot of cows.

Down here at NCSU the guys in the lab coats have looked very closely at
biogas for the past few years. I think the consensus is that even in a very
concentrated operation (they're looking at CAFO's like pig, turkey and
chicken farms)
it doesn't really pay to develop a system around gas sales. They're looking
at other directions in post-manure products, like high protein animal feeds.
Black soldier fly larva would be an example. If you want to check out one of
the
really good research schools on the subject, start here:

http://www.cals.ncsu.edu/an_sci/annrep95/swine/swin9514.html

http://www.bae.ncsu.edu/programs/extension/publicat/wqwm/ebae071_80.html

http://www.hydroponics.com.au/back_issues/issue59.html

http://www.epa.gov/agstar/pdf/ag_fund_doc.pdf

Finally, here's something from the middle of a long conversation on another
list about the subect. Scroll forward or backward and you can find much
useful
info:

http://listserv.repp.org/pipermail/digestion/2004-May/000406.html




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