[Gasification] biochar to sequester carbon

Tue Oct 9 05:25:40 EDT 2007

I have not investigating the char of Terra Preta myself. I fully rely on
presentations by Danny Day. I do not know its cationic activity. What I
did was putting fly ash from fluid bed gasification of wood under the
electron microscope and compare it with photos presented by Danny Day.
His stuff looks like Swiss cheese. Our char looks like glass splinters
of 20 micron. No internal porosity, only outer surface area. Given fact
that it has also not been activated to create exchange sites (like
activated carbon has) it contains very little cationic exchange
properties. Maybe Terra Preta does.

I only want to claim that gasification char when made at typical
gasification temperatures (800-900 degC) are unlikely to play a
significant role in soil and cannot play the role that pyrolysis char
(made at 500-600 degC) can play in soil. You must be pretty desperate to
put that in the ground for improving soil quality beyond straightforward
supply of nutrients.

Perhaps not keeping an eye on the morphology explains why "the results
are not yet clear" as said by Tom. Another reason might be that if soil
already contains lots of humus (as often in temperate zones) char is not
adding to the capacity to keep nutrients from leaching away.

Jan

========================================
Dr. Jan R. Pels
ECN - Biomass, Coals and Environmental Research
P.O. Box 1, 1755 ZG Petten, The Netherlands
telephone: +31-224-564884; fax: +31-224-568487
mobile: +31-6-10923218
e-mail: pels at ecn.nl
========================================

> -----Original Message-----
> From: gasification-bounces at listserv.repp.org 
> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of 
> Ken Calvert
> Sent: Tuesday, October 09, 2007 10:55 AM
> To: Discussion of biomass pyrolysis and gasification
> Subject: Re: [Gasification] biochar to sequester carbon
> 
> All O.K.on the biological side but what about the  cation 
> exchange properties?  I thought that Tera preta was mainly 
> about holding onto 
> fertiliser molecules before they were leached out of the 
> system?   Ken C.
> ----- Original Message -----
> From: "Pels, J.R. (Jan)" <pels at ecn.nl>
> To: "Discussion of biomass pyrolysis and gasification" 
> <gasification at listserv.repp.org>
> Sent: Tuesday, October 09, 2007 9:46 PM
> Subject: Re: [Gasification] biochar to sequester carbon
> 
> 
> > Dear List,
> >
> > As far as I understand the Terra Preta issue, it is basically the 
> > morphology of the char that is beneficial. The chemical 
> composition of 
> > the char is not relevant. After pyrolysis or degassing an open 
> > structure is formed where microorganisms and fungi find a 
> suitable place to live.
> > They are improving soil quality by retaining water and 
> nutrients. When 
> > made at low temperature the char retains much of its 
> original biomass 
> > structure.
> >
> > Unfortunately, in high-temperature gasification, this 
> structure is lost.
> > Carbon-rich fly ash from gasification of biomass is composed of 
> > non-porous graphite-like particles and thus not functional in Terra 
> > Preta.
> >
> > Not all char is equal.
> >
> > Jan
> >
> >
> > ========================================
> > Dr. Jan R. Pels
> > ECN - Biomass, Coals and Environmental Research P.O. Box 1, 1755 ZG 
> > Petten, The Netherlands
> > telephone: +31-224-564884; fax: +31-224-568487
> > mobile: +31-6-10923218
> > e-mail: pels at ecn.nl
> > ========================================
> >
> >
> >
> >> -----Original Message-----
> >> From: gasification-bounces at listserv.repp.org
> >> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of Tom 
> >> Miles
> >> Sent: Tuesday, October 09, 2007 5:56 AM
> >> To: 'Discussion of biomass pyrolysis and gasification'
> >> Subject: Re: [Gasification] biochar to sequester carbon
> >>
> >> Reg,
> >>
> >> Your find discussions of this an related articles on the 
> terra preta 
> >> discussion list and website that we started in January.
> >> http://terrapreta.bioenergylists.org/
> >> http://bioenergylists.org/pipermail/terrapreta_bioenergylists.org/
> >>
> >> You will find links there for Cornell where Lehmann is and other 
> >> charcoal research. Some people on the discussion list have started 
> >> their own farm and garden tests of charcoal, on arid soils 
> in Guinea 
> >> and Australia, on alkaline soils in India, in China, "somewhere 20 
> >> miles south of Lake Erie, USA," in a nursery in Washington, etc.
> >>
> >> We're all learning what the agronomic value of the 
> charcoal might be 
> >> for different soils and plants. The results are not yet clear. At 
> >> best it would be a good use for char from gasifiers.
> >>
> >> Tom
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: gasification-bounces at listserv.repp.org
> >> [mailto:gasification-bounces at listserv.repp.org] On Behalf Of Reg 
> >> Preston
> >> Sent: Monday, October 08, 2007 12:43 AM
> >> To: Discussion of biomass pyrolysis and gasification
> >> Subject: [Gasification] biochar to sequester carbon
> >>
> >> http://www.biochar-international.org/images/Lehman_Handful_of_
> >> C_-_Nature_5.9
> >> .07.pdf
> >>
> >> I trust every one on the list has read this paper?  
> Comments would be 
> >> appreciated.
> >>
> >> Reg Preston
> >>
> >>
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> >>
> >>
> >>
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> >>
> >
> > _______________________________________________
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> > 
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> > 
> 
> 
> 
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