[Digestion] Digestion Digest, Vol 31, Issue 2

[rongretlarson at comcast.net]

Digestion list 

1. This is to follow up on the sequence in Message #1, saying 

BURNING Vs FERMENTATION - THE NEVER ENDING DEBATE 
<snip> 
and Dr. Chanakya stated about fermentation: 
" I am not so sure that there is a more energy efficient way to recover energy from cattle dung. " 

2. I have been following this list from its very beginning - but I am a real outsider on dgestion. My main interest has been charcoal-making stoves and have switched to an interest in biochar and especially carbon negativity. To the best of my knowledge digestion effluent is rarely pyrolyzed - but could be? 
I am willing to agree that digestion is superior to combustion (burning). But since I think carbon negativity is so important, I wonder what this list's answer would be to the question : 
PYROLYSIS Vs FERMENTATION - A DIFFERENT DEBATE 

3. There is a form of biochar called Hydrothermal Carbonization (HTC) - which also has to work with wet materials. Same questions - whch largely should revolve around the costs of drying, carbon removal climate benefits, the longevity in soil of char vs effluent, the recovery of nutrients, etc. 

4. I am a regular on the Google list called "Geoengineering", where I have recently begun asking whether biochar/pyrolysis would not be helpful in carbon dioxide removal (CDR) using ocean biomass. There are a few people on that lst who have been arguing for using a fertilizer (maybe deep cean waters) to enhance the growth of selected ocean biota. This biomass would be put into a digester (presumably a large plastic bag), and the resulting methane harvested and the energy somehow shipped to shore. The effluent would be released to sink to the ocean bottom to achieve CDR. My preference would be pyrolysis, perhaps on shore, with a more sure CDR, and out-year soil improvement benefits. 
Comments? 

Thanks in advance for any thoughts or citations 

Ron ( a digest recipient) 

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Message: 1 
Date: Sat, 2 Mar 2013 21:36:52 +0530 (IST) 
From: "Hoysall Chanakya" <chanakya at astra.iisc.ernet.in> 
To: "For Discussion of Anaerobic Digestion" 
<digestion at lists.bioenergylists.org> 
Subject: Re: [Digestion] Sulphur levels 
Message-ID: 
<49747.10.16.40.14.1362240412.squirrel at mail.astra.iisc.ernet.in> 
Content-Type: text/plain;charset=iso-8859-1 

Biogas Friends 

Just a small correction to this train of thought 
BURNING Vs FERMENTATION - THE NEVER ENDING DEBATE 

Measured Cal value of dry dung = 3100kCals/kg 
Conversion of wet dung at 18% moisture = 40L/kg @60% methane 

This works out to (0.040 X 5500kCals/m3) ? 0.18 (correction for moisture) 
= 1222kCal (or about 40% energy recovery efficiency 

I am not so sure that there is a more energy efficient way to recover 
energy from cattle dung. 

Best wishes 
Chanakya 

-- 
Dr. Hoysall Chanakya 
Centre for Sustainable Technologies 
(Assoc. Faculty at Centre for Infrastructure, Sustainable Transport and 
Urban Planning (CiSTUP) and Centre for Contemporary Studies) 
Indian Institute of Science, Bangalore 560 012 
ph 91-80-2293 3046; fax-91 80 2360 0683 


Message: 2 
Date: Sat, 2 Mar 2013 22:44:41 +0530 
From: Anand Karve <adkarve at gmail.com> 
To: For Discussion of Anaerobic Digestion 
<digestion at lists.bioenergylists.org> 
Subject: Re: [Digestion] Sulphur levels 
Message-ID: 
<CACPy7Se+=jOsszSQobS5ko7NJZx3p4j9rqPvEg_o+xBgs=heYw at mail.gmail.com> 
Content-Type: text/plain; charset=ISO-8859-1 

Dear Chanakya, 
thanks for the correction. I think, I had used the value of methane 
obtained from the dung of a water buffalo. 
Yours 
A.D.Karve 


Message: 3 
<snip - different topic> 
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