[Bioconversion] methane digester and greenhouse gas reduction fordemonstration post-carbon world home

Tue Jun 12 11:08:06 CDT 2007

Thanks, Hooroo.

Regarding the sums,the CO2 released by today's feedstock is today's CO2,
which is better than introducing ancient CO2 from fossil fuel combustion,
which is an unnatural addition to today's CO2 pool and cycle.  However, I
would like to know if I am reducing today's CO2 release by
anaerobic-methane-combustion-CO2 versus the release of CO2 of the same feed
stock by decomposition in Nature.  This would be a great plus in a world
where we need to not only reduce human-induced CO2 emmission but natural
emission as well, since the atmosphere is overloaded and the Nature's
carbon-fixers are depleted.

Regarding the extent of conversion of human waste, you are saying the longer
the anaerobic digestion takes place, the more complete the conversion to a
benign compost.  Question is are we talking months or years after feedstock
introduction ceases.  I need to know how long I need the offline tank rest
to assure a benign compost.  The second, active tank can stay online for
years if need be to allow the resting tank to complete the anaerobic
digestion.

PHil

Philip Anderson
Sustainable Living Design

Life support & life style in partnership
 with Nature and in harmony with the heart

11801 Pine Court
Monrovia, MD 21770-8802   USA     

Phone (301) 335-6051
Fax (301) 865-3642

  solarphil at comcast.net

-----Original Message-----
From: bioconversion-bounces at listserv.repp.org
[mailto:bioconversion-bounces at listserv.repp.org] On Behalf Of Paul Harris
Sent: Tuesday, June 12, 2007 2:09 AM
To: Discussion of biological conversion to fuels and chemicals
Subject: Re: [Bioconversion] methane digester and greenhouse gas reduction
fordemonstration post-carbon world home

G'day Philip,

Without doing the sums anaerobic digestion wins, as it relaces fossil
fuels as well as capturing a 20 times more potent GHG!

The longer the retention time and the more steps/hosts waste goes
through the safer it is (and the more robust the system is!).

Hope this helps,
HOOROO

Philip Anderson wrote:
> 
> Greetings bioconversioneers!  I$B!G(Bm back after a year -Phil Anderson
- and
> still working on a house plan which demonstrates living in partnership
with
> Nature, including benign, site-produced energy and net zero greenhouse gas
> production.
> 
> I want to produce methane gas for cooking in the first cell of a
constructed
> wetlands blackwater treatment system. This first cell is in effect a
septic
> tank which I will seal (polyethylene tank) to use like ARTI$B!G(Bs
domestic
> biogas plant (http://www.arti-india.org/content/view/45/52/) which
operates
> without animal fodder (so it is feasible to be used off the farm in
> America).  But our plant will also digest human waste in addition to food
> scraps and landscape cuttings as ARTI$B!G(Bs uses.
> 
> I will construct two first cells (two $B!H(Bseptic tanks$B!I(B) in the
wetlands
> blackwater treatment system, so one can be online while the other rests
and
> its digested residue is harvested as compost.
> 
> Please comment:
> 
> 1.  Is this system actually reducing the greenhouse effect which the
> feedstock would have produced in Nature aerobically?  See
Wikepedia$B!G(Bs
> equation for methane combustion below.  Per unit of feedstock what
produces
> more greenhouse effect:   anaerobic digestion where the methane is
captured
> and burned releasing CO2 and water, or aerobic digestion where CO2 is
> released without burning?
> 
> Per Wikepedia:  $B!H(B Burning <http://en.wikipedia.org/wiki/Combustion>
one
> molecule <http://en.wikipedia.org/wiki/Molecule>  of methane in the
presence
> of oxygen <http://en.wikipedia.org/wiki/Oxygen>  releases one molecule of
> CO2 (carbon <http://en.wikipedia.org/wiki/Carbon_dioxide>  dioxide) and
two
> molecules of H <http://en.wikipedia.org/wiki/Water> 2O:
> 
> CH4 + 2O2 $B"*(B CO2 + 2H2O $B!H(B
> 
> Another way to phrase the question: given the same unit of feedstock is
less
> C02 released to the atmosphere by the anaerobic-methane-combustion system
> than the aerobic system?
> 
> 2.  I$B!G(Bm thinking that at least the burning of the methane from the
> $B!H(Bseptic$B!I(B cell /tank (rather than its finding its way out to
the
> atmosphere), is reducing the greenhouse effect since methane has about 20
> times more greenhouse effect than C02, and the combustion formula shows
one
> methane molecule yielding only one carbon dioxide molecule in the
combustion
> reaction  --95% reduction in greenhouse effect?   Or would the same unit
of
> feedstock produce the same amount of CO2 via either process (aerobic
> production of CO2 or anaerobic production of methane which is then burned
to
> produce CO2)?
> 
> 3.  Is the feedstock in aerobic digestion converted to a material which
can
> be used as compost or is it unsafe sludge? How long does it take to
produce
> a safe compost, and how do we know when this process is complete?  Again,
my
> design calls for two anaerobic cells, one of which will be online
/handling
> blackwater while the other is cleared of the digested material for use as
> compost.
> 
> Again, the benefits I would like to have from this system:   compost from
> human waste, site-produced cooking fuel and net zero or even reduced
> greenhouse effect as compared with the gases produced by the natural
aerobic
> and anaerobic decomposition of the same feedstock.  Do I have the system
I$B!G(B
> m aiming for?
> 
> Thanks,
> 
> Phil
> 
> _______________________________________________
> Bioconversion mailing list
> Bioconversion at listserv.repp.org
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-- 
Mr. Paul Harris
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Faculty of Sciences,
The  University of Adelaide, Roseworthy Campus, AUSTRALIA 5371
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