[Terrapreta] Charcoal properties

[danny day]

Michael, thanks jumping in.
 You have as much experience as anyone I know in this field.

Everywhere I go people ask me how they can make their own char and I tell
them from my experience, make a small campfire and use a hose with a mist
nozzle to keep the charcoal in cool as it pyrolyzes.  Without instruments,
(and this is not a rule for all biomass sources)  a  charcoal  that sinks in
water was made too hot but  saying that any which floats is the best is not
accurate either.  We are all working on finding the best char but I believe
we will find it is much more complex than that.  The evolutionary
development of soil life and its interactions with char have some very
interesting revelation to come.  Michael, your lab is as qualified as any to
make standardized char.  One which support a biological response of the
microbial environment which can create an environment for a specific crop is
part of the knowledge base that we can help can contribute.  I trust soon
that we can begin to support labs around the world for providing the
analytical testing needed.

It's exciting isn't it?

Danny Day

Eprida

On 3/3/07, Sean K. Barry <sean.barry at juno.com> wrote:
>
>  Hi Michael,
>
> Thank you for your very interesting comments.  By what you have said in
> your post, ...
>
> "Tests by my colleague Professor Goro Uehara and his co-workers in CTAHR
> have
> shown that the addition of some charcoals to the soil can be harmful to
> plant growth.  Our analyses of the properties of this "harmful" charcoal
> indicate that it would have been perfect for barbeque."
>
> and ...
>
> "A good barbeque charcoal will have a VM content of 25 - 30%, whereas a
> charcoal destined for metallurgical use often has VM content below 10%."
> ... would it be fair to infer, then, that relatively high volatile matter
> content (25 - 30%) in charcoal probably does not make a good agricultural
> use charcoal?  Has anyone tested metallurgical use charcoal (@ <10% VM) as
> an AgChar?  What are the pyrolysis conditions under which metallurgical use
> charcoal is made (feedstock, temperature, oxygen or air supply level,
> etc.)?  Are there any simple methods (not involving expensive gas
> chromatographs and/or other equipment) to test for VM content?  Like, maybe
> does low VM charcoal combust at a lower or higher temperature the higher VM
> charcoal?  Do they have a different densities?
>
> You say, "This is not an easy job and there are no short cuts that I can
> find."  So maybe my questions seem like naivete, but what I am interested in
> learning from you is if a fuel scientists/chemical engineer like you really
> does maybe know some possible simple methods to do proximate analysis of
> charcoal or maybe some parts of it.  Not everyone interested in testing or
> making Terra Preta has your kind of background, nor access to the kinds of
> scientific equipment you do.  But, I suspect that there are low tech ways to
> accomplish some of the things you are doing with your analysis of charcoal
> properties.  Hopefully, you may be willing to at least discuss the
> possibilities.
>
> Would you be willing to put your papers online for the group?  I'm
> interested, so if you like, send them to me.
>
>
> Thank you and regards,
>
> Sean K. Barry
> Principal Engineer/Owner
> Troposphere Energy, LLC
> 11170 142nd St. N.
> Stillwater, MN 55082
> (651) 351-0711 (Home/Fax)
> (651) 285-0904 (Cell)
> sean.barry at juno.com
>
> ----- Original Message -----
> *From:* Michael J. Antal, Jr. <mantal at hawaii.edu>
> *To:* terrapreta at bioenergylists.org
> *Sent:* Friday, March 02, 2007 2:28 PM
> *Subject:* [Terrapreta] Charcoal properties
>
> Dear friends: terra preta is fascinating in part because it involves so
> many
> disciplines.  My viewpoint is that of a fuel scientist/chemical engineer.
> My laboratory produces well-characterized charcoals for a wide variety of
> research endeavors, including carbon fuel cell studies, metallurgical
> charcoal applications, activated carbon production, and terra preta
> research
> (with my colleagues Dr. Goro Uehara, Dr. Jonathan Deenik, and Tai
> McClellan
> in the University of Hawaii's College of Tropical Agriculture and Human
> Resources).  With this message I wish to call your attention to the
> elementary properties of charcoal that I think about when I am producing a
> charcoal for one of our research endeavors.
>
> Both the feedstock and the process (i.e. pyrolysis) conditions influence
> the
> properties of the charcoal product.  For example, oak wood has little ash;
> consequently its charcoal also has little ash.  On the other hand, rice
> hulls have much ash (nearly pure silica), and so does its charcoal.
> Likewise corncobs produce a highly macroporous charcoal, whereas sucrose
> charcoal lacks a macroporous structure.  But unfortunately, the properties
> of the feedstock do not completely determine the properties of the
> charcoal.
> For example, if pyrolysis is carried out at a high temperature, some of
> the
> volatile ash components leave the charcoal.  In our work it is not unusual
> to find that the charcoal contains as little as 20% of the amount of ash
> that we expected on the basis of the feedstock ash content.  One carbon
> company produces an ash-free carbon for metallurgical applications by
> simply
> heating a fossil carbon (usually coal) to such a high temperature that
> virtually all the minerals in the fossil carbon vaporize.
>
> Likewise the pyrolysis temperature (usually called the "heat treatment
> temperature" or HTT) exerts a big influence on the properties of the
> carbon.
> Fuel scientists employ proximate analysis to measure this influence.
> Let's
> be clear: there is nothing approximate about proximate analysis!
> Proximate
> analysis determines the moisture content (mc), volatile matter (VM)
> content,
> fixed carbon (fC) content, and ash content of a charcoal (or fossil
> carbon).
> A good barbeque charcoal will have a VM content of 25 - 30%, whereas a
> charcoal destined for metallurgical use often has VM content below 10%.
> Increasing HTT lowers the VM content of the charcoal, but there is not a
> simple relationship between the HTT and the charcoal's VM content.  Why?
> The simplest explanation is that the thermocouple used to measure the HTT
> measures the temperature of the pyrolysis environment: it does not measure
> the temperature of substrate during pyrolysis!  Pyrolytic reactors
> designed
> to maximize "oil" (or gas) yields - and minimize the charcoal yield -
> employ
> high heating rates.  Under these conditions the pyrolysis reactions are
> endothermic; consequently there is a large temperature difference between
> the charcoal and its environment (i.e. the temperature of the charcoal can
> be hundreds of °C lower than its environment).  On the other hand, a
> pyrolytic reactor that is designed to maximize the charcoal yield will
> evoke
> exothermic pyrolysis reactions in the substrate, since the reactions that
> form charcoal are exothermic.  In this case the temperature of the
> charcoal
> can be much higher than its HTT.  I can provide some interesting papers on
> this subject for anyone who is interested.
>
> In summary, both the feedstock and the pyrolysis process conditions
> influence the properties of the charcoal product, but they do not
> determine
> the properties (i.e. knowing the feedstock and process conditions is not
> enough to predict the properties of the charoal).  The only way to
> determine
> the charcoal's properties is to actually measure them.  We do proximate
> analyses of all our charcoals.  Often we do gas sorption measurements to
> determine the carbon's surface area and pore volume distribution.
> Sometimes
> we obtain an elemental analysis of the carbon, or an analysis of its ash
> content.  For our carbon fuel cell work we measure the carbon's electrical
> conductivity, and with colleagues in the Hungarian Academy of Sciences we
> do
> temperature-programmed desorption of biocarbons used in our fuel cell.  We
> have done XRD, NMR, ESR, and MALDI-TOF MS analyses of some of our
> charcoals.
> We have plans to expand our analysis capabilities into other areas soon.
>
> Tests by my colleague Professor Goro Uehara and his co-workers in CTAHR
> have
> shown that the addition of some charcoals to the soil can be harmful to
> plant growth.  Our analyses of the properties of this "harmful" charcoal
> indicate that it would have been perfect for barbeque.  This illustrates
> the
> dangers of working with an uncharacterized charcoal purchased from your
> local grocery store.  Professor Uehara and his co-workers will have more
> to
> say on this subject in the near future.  In the meantime I emphasize that
> our understanding of charcoal's beneficial and detrimental effects on
> plant
> growth must rest (in part) upon measurements of the charcoal's properties.
> This is not an easy job and there are no short cuts that I can find.
>
> Like most of you, at present my terra preta research is not funded, so the
> best I can do is provide well-characterized charcoals to my colleagues
> here
> at UH.  In the future I may have the resources to provide
> well-characterized
> charcoals to other terra preta researchers as well.  I will let you know
> when this becomes possible.
>
> Best wishes, Michael.
>
> Michael J. Antal, Jr.
> Coral Industries Distinguished Professor of Renewable Energy Resources
> Hawaii Natural Energy Institute
> School of Ocean and Earth Science and Technology (SOEST)
> 1680 East-West Rd., POST 109
> University of Hawaii at Manoa
> Honolulu, HI 96822
>
> Phone: 808/956-7267
> Fax: 808/956-2336
> http://www.hnei.hawaii.edu
>
>
>
>
>
>
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-- 
Danny Day
President
EPRIDA
404-202-6105 Cell
706-621-7651 Office
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