[Gasification] Biochar production by Amazonians - Was [biochar] Pine char gasification

rcwarship . rcwarship at gmail.com
Thu Dec 26 14:08:29 CST 2013


I just started reading MORGAN J. SCHMIDT's dissertation on the very subject
of how the natives created terra preta.  I admit upfront that I won't be
studying the whole document, just skimming/studying the pertinent
sections.  It's been a very informative read so far.
Best Regards To All,
Jon

http://marte.museu-goeldi.br/arqueologia/pdf/schmidt_m2.pdf


"RECONSTRUCTING TROPICAL NATURE: PREHISTORIC AND MODERN ANTHROSOLS (TERRA
PRETA) IN THE AMAZON RAINFOREST, UPPER XINGU RIVER, BRAZIL"


On Thu, Dec 26, 2013 at 3:38 AM, Kevin C <kchisholm at ca.inter.net> wrote:

> Dear Ron
>
> Quoting "Ronal W. Larson" <rongretlarson at comcast.net>:
>
>  Tom  - see notes below.  I have little time for a few more weeks, but
>> will try to get back to this, if others haven’t already supplied enough of
>> a response.
>>
>>
>> On Dec 23, 2013, at 4:36 PM, Tom Miles <tmiles at trmiles.com> wrote:
>>
>>
>>> Ron,
>>>
>>>
>>>
>>> I didn’t mean anything quite so personal. :-/
>>>
>>>       [RWL1:  See next response to Mark Ludlow.  I was mostly trying to
>> get some humor injected - about my own “cult”.
>>
>>>
>>>
>>> Most of the biochar research has focused on pyrolitic char and not on
>>> combustion or gasification char. There is a clear bias toward pyrolysis, or
>>> low temperature char. Can anyone really say this is the way that the
>>> Amazonians, or anyone else, created the charcoal that we find in the terra
>>> preta soils? Or was it smoldering combustion, staged combustion (a la Alex
>>> English), or a combination of pyrolysis, gasification and combustion? I
>>> know that I have had a lot of bad slash and straw burns that have left a
>>> lot more char on the ground than ash. Are there “signatures” in the terra
>>> preta char that point specifically to pyrolysis, gasification or combustion?
>>>
>>>        [RWL2:  I just spent half an hour trying to find something
>> definitive.  I found one Ppt by three friends on this topic,  but not
>> enough words to go with the pictures.  I will check after Xmas.
>>     I hope someone on this list has looked at efforts to mimic the Terra
>> Preta soils.
>>
>
> # KC: This seems to be "The Unspoken Elephant in the Room." Just how did
> the Terrapretians actually make Terra Preta??? Did they actually make it on
> purpose, OR did it just happen, when they disposed of wastes, either
> ``jungle wastes`` or ``domestic wastes``? What is the difference between
> making "Terra Preta" and the Milpa Agriculture, as practised in Belize?
>
>  It seems clear they did much more than just put
>
>> out ash - which seems to have been what the vast majority of aboriginal
>> slash and burn cultures did.
>>
>
> # KC: The inorganic fraction of the char remaining from "slash and burn"
> could be one possible explanation for the presence of charcoal in the soil.
>
>   I favor an argument that the
>
>> char came from what happened during and after cooking (If wood is easy to
>> come by, you can make a lot of char in a 3-stone arrangement.
>>
>
> # KC: Certainly, there was an excess of wood available.... a "jungle full
> of wood." However, it was certainly not easily available... there would be
> an enormous labour content requirement to cut down trees and prepare the
> wood for use as a fuel, with only "Stone Age Implements and Technology."
> The ``Amazonian Terrapretians`were no doubt just as smart and just as lazy
> as Modern Day Men. Those who have chopped down a hardwood tree with a sharp
> axe can appreciate the difficulty of chopping down jungle trees with a
> relatively blunt stone age axe.
>
>   I have seen one argument for an approach like HTC.
>>
>
> # KC: The possibility of using the nutritious ``black goop`` from the
> bottom of the Òxbow Lakes that are very common along the Amazon River has
> been suggested as a source of fertiliing nutrients for Terra Preta on this
> list in the past, and the concept was received with extreme disinterest. I
> would suggest that the ``black goop``was made by the `LTAHTC Process``, ie,
> the ``Low Temperature Anaerobic HydroThermal Carbon Process``
>
>>
>>>
>>> I see biochar production growing in stages. For the time being a large
>>> quantity of char that is sold as Biochar is actually char from
>>> gasification. As biochar markets grow we might expect to find more
>>> pyrolytic char made “for purpose” but now we have some pyrolitic char and
>>> byproducts of gasification (including TLUDs) and combustion.
>>>
>>>     [RWL3:  I wouldn’t couple the words “TLUDs” and “gasification”.
>>> TLUDs look like pyrolysis to me.
>>>
>>
> # KC: Also in the past on one of these lists (Biochar...Gasification...
> Stoves...) were extensive discussions on the subject of whether a TLUD was
> a `Gasifier Stove`or not. The conclusion at the time seems to have been
> that the TLUD was indeed a gasifier, that was close coupled to a stove .
> Given that gases are produced in pyrolysis, it would seem fair to accept as
> a fact that pyrolysis is a `gasification process.
>
>
>
>>> The “high temperature” gasifier char performs very well and in some
>>> applications better than pyrolytic char. Several studies (and some
>>> commercial producers) have found that conditioning the char through
>>> partially oxidation (to higher temperature) enhances nutrient retention.
>>> These products are for improving soil fertility , not necessarily to
>>> replace activated carbon. So why not consider CO2 gasification as a
>>> possible process step?
>>>
>>>    [RWL4:   I need help on this.  I am assuming that adding CO2 to hot
>>> char is designed to leave little char.   Doesn’t sound like a major help
>>> for producing a biochar.
>>>
>>
> # KC: The ``Pillar of Agricultural Biochar`` seems to be Terra Preta.
> Perhaps someone could provide evidence of some sort showing how the
> Amazonian Terrapretians controlled their char making temperatures.
>
>>
>>> One major producer of char in California uses a downdraft gasifier. In a
>>> downdraft gasifier wood devolatilizes at or above the oxidation zone.
>>> Volatile carbon is oxidized by the air injected from nozzles to make CO2.
>>> The hot CO2 reacts with the char to form CO and H2. This occurs in the
>>> “reduction zone”. The reduction zone is often shown as a deep bed of carbon
>>> but in fact it is usually only a couple of inches thick. Large chips reduce
>>> to powdered char in less than 2 inches where gas temperatures are 800-900C.
>>> The resultant producer gas is a mixture of this CO from reducing char and
>>> the devolatilized gas. Taking CO2 and reacting it with charcoal at 800-900C
>>> as Purdue has done is not a lot different so the qualities of the char
>>> should be similar.
>>>
>>>
>>>
>>>      [RWL5:   Still need help  (not knowing enough about the term
>> “gasification”).  In downdraft gasifiers, I have been assuming that the
>> injected air was reacting mostly with the char, not with the already
>> produced gases.  The intent was to get rid of as much char as possible (and
>> I assume the same for the Purdue researchers).   I understand that Purdue
>> is inputting CO2 and not air (in a second stage), but the intent in both
>> cases is (I presume) to leave as little char as possible.   I just don’t
>> see how that fits into this list - interested in getting a lot of char.   I
>> understand that part of the processing is to maximize CO and H2.    I’ll
>> try to get back to this.
>>
>
> # KC: The problem seems to be when those interested in producing
> ``Biochar`` for Agricultural Purposes get into conflict with those who want
> to produce ``Biochar```for ``Climate Change Purposes``, or other purposes.
> A clear definition of ``The Various Biochars`` would indeed be helpful
>
>>
>>  I think we need to explore all avenues of producing char and energy
>>>
>>> 1.      Slow pyrolysis – 25%-30% char; 30% oil+gas
>>>
>>> 2.      Fast pyrolysis – 15% char; 60% oil
>>>
>>> 3.      Gasification – 5%-25% char; 75%-95% energy
>>>
>>> 4.      Combustion – 1-5% char; 95% heat
>>>
>>>
>>     [RWL:  Tom - the bottom two total near 100%, but not the top two; can
>> you add some more components?.  I am surprised also to see gasification
>> char as high as 25%;  who is getting this high - and how?.
>>
>
> # KC: There are indeed a lot of different kinds of chars that are produced
> by various means, for various purposes, from various feedstocks, and at
> various temperatures. It seems that there are still a lot of ``loose ends``
> associated with ``Char``, ``Biochar``, etc.
>
>>
>>     Adding to this list might be the work of Mike Antal (and Mantria)
>> with added pressure.  Also Cool Planet uses pressure and catalysts with the
>> term “fractionator”.   Retort char (zero oxygen) could be a little
>> different from your four - all of which involve some O2?.  Maybe same for
>> char made with microwaves (heating from the inside of particles being
>> different)?   Certainly HTC  (hydrothermal carbonization) is very
>> different.  Is the approach by Alex English different from any of these  (I
>> think it is close to slow pyrolysis).  Nat Mulcahy with World Stove has a
>> different approach with no oxygen flowing through the fuel bed.  Jim
>> Mason’s BEK will be called gasification?
>>
>
> # KC: You make a very good case for the need for the IBI to clean up their
> definition of ``Biochar``.
>
>>
>>     I heat my home partly with wood (mostly solar (except when cold and
>> cloudy), no gas) - and have pulled copious amounts of char out of my (open
>> front) stove - a lot more than 5%.  I believe that has to be called
>> interrupted combustion - just the same as the whiskey maker Jack Daniels
>> does - combustion interrupted at the end of the pyrolysis stage and before
>> much gasification can have occurred.  The difference seems to be whether an
>> O2 molecule can reach a hot char surface or not - because of still-exiting
>> pyrolysis gases getting oxidized first (mainly to CO and H2O).
>>
>
> # KC: With all this char being available to you, it would be interesting
> to see your comments on tests that you have probably done, using this kind
> of char as a soil additive for improving plant growth.
>
>>
>>
>>      All in all I think it great that there are so many carbonization
>> approaches - hopefully enough for every combination of soil and plant
>> species.    The big divider will be process temperature, it seems.
>>
>
>  # KC: It would be very interesting to see your comments on which kinds of
> chars are best for the various end uses to which the various chars can be
> put.
>
> Best wishes, for ``Biochar Clarification`in 2014``.
>
> Kevin
>
>  Ron
>>
>>>
>>>
>>> Tom
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> From: biochar at yahoogroups.com [mailto:biochar at yahoogroups.com] On
>>> Behalf Of Ronal W. Larson
>>> Sent: Monday, December 23, 2013 2:53 PM
>>> To: Biochar; Tom Miles
>>> Cc: Crispin Pemberton-Pigott; Gasification-Request
>>> Subject: Re: [biochar] Pine char gasification
>>>
>>>
>>>
>>>
>>>
>>> Tom etal:
>>>
>>>
>>>
>>>    1.   I’m not sure I want to accept the “philia” part of this message
>>>  (“philia” goes with “abnormal” and pedophilia at one google site).  I
>>> found the word agape - but that sounds presumptuous.  But I do admit to
>>> being at the non-sensical end of the char spectrum.  Maybe charphilia is
>>> apt.
>>>
>>>
>>>
>>>   2.  I know close to zero about any part of gasification, but I can
>>> understand why one would promote the idea of recycling the CO2 to get more
>>> gas (eventually the Purdue group wants liquid, it seems).  But that has to
>>> result in less char - and apparently leaves much higher temperature char.
>>>  Eventually it is almost all CO2, for gasification, but I worry that the
>>> char produced this (high temperature) way might only be suited to replace
>>> AC = activated carbon.
>>>
>>>
>>>
>>>   3.  Since Alex English name came up today, we should note that he also
>>> recycles CO2.
>>>
>>>
>>>
>>>   4.  The dogma of the cult I am in says more char beats more heat, gas
>>> or liquid, so I will look forward to some proof that is not correct.
>>>
>>>
>>>
>>>  Good luck to the Purdue folk.
>>>
>>>
>>>
>>> Ron
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>> On Dec 23, 2013, at 12:58 PM, Tom Miles <tmiles at trmiles.com> wrote:
>>>
>>>
>>>
>>>
>>>
>>>
>>> Ron,
>>>
>>>
>>>
>>> This work is very important for both the biochar and gasification lists.
>>> Biochar will be produced at the large, or even small, scale as a co-product
>>> of energy (liquid fuels and/or power). The most efficient way to generate
>>> power from the gases and vapors from slow pyrolysis (50% of the energy) is
>>> probably through charcoal gasification (e.g. run the pyrolysis gases
>>> through a charcoal gasifier). There are commercial systems under
>>> development to make char and power in this way. There are also commercial
>>> systems under development to make liquid fuels through combinations of
>>> pyrolysis and gasification. The char products from these and fast pyrolysis
>>> processes run from 0% to about 15% of fuel input. I don’t know the fuel or
>>> char yield for Cool Planet.
>>>
>>>
>>>
>>> This particular study prepared the char with high temperature (826 C)
>>> nitrogen.  Wood particles (chips, sawdust) and resultant char particles in
>>> this study are larger than for other char studies. Obs
>>>
>>>
>>>
>>>
>>> ervations about BET surface area, particle size and the char morphology
>>> are very interesting. The char morphology looks different than the SEM
>>> images that we typically see. From gasification and pyrolysis we know that
>>> pine carbonizes differently than hardwood so it is interesting to see the
>>> shredded fibrous appearance of the pine char in this study compared to the
>>> neat geometric structures that we often see, which is probably from
>>> hardwood chars. The authors observe that the macropore volume is
>>> significantly greater than the mesopore or micropore volume of the char.
>>> They observe “numerous wide tunnel protruding into the char particles. . .
>>> [that] may provide pathways for bulk transport of CO2 into the particle.”
>>>
>>>
>>>
>>> Char conversion numbers are interesting. Only 10-12% of the char was
>>> gasified at 726 C (BET 391 m3/g) while 98-100% was converted at 896 C.
>>> Surface area increased with conversion but not much greater than the 35-47%
>>> conversion at 776 C so CO2 gasification could be used to increase surface
>>> area at the expense of half of char (660 m3/g). Meso and micro pore volume
>>> doubles at the higher rate but stays pretty constant above 776 C.
>>> Researchers conclude that a significant proportion of the pore volume is
>>> within macro pores although the majority of the internal surface area is
>>> within micro pores.  They point out that the mass loss with surface
>>> gasification occurs within the smaller pores leading to pore widening.
>>>
>>>
>>>
>>> Researchers explain that the char gasification process involves three
>>> steps: (1) adsorption of the gas-phase species to the char surface, (2)
>>> surface reactions, and (3) desorption of the gasification products from the
>>> surface. The latter is the rate limiting process.
>>>
>>>
>>>
>>> Recycling CO2 from gasification to gasify the char is an interesting
>>> concept that may apply to modifying char properties (e.g. increase surface
>>> area) from pyrolysis or recovering energy (heat, power, syngas) in an
>>> industrial setting.
>>>
>>>
>>>
>>> There is very little information about gasification or combustion chars.
>>> Sometimes it helps to step back from our char-philia (and gaso-phobia) to
>>> see what products combined pyrolysis and gasification can produce.
>>>
>>>
>>>
>>> Tom
>>>
>>>
>>>
>>>
>>>
>>> RL> don’t see any relevance to the biochar list.  (Except if this work
>>> shows that char is more valuable in the ground and/or that an approach like
>>> Cool Planet’s is more efficient.)  On the biochar list, we should want BOTH
>>> high value fuels and charcoal.
>>>
>>>      This Purdue work is all about gasification of char - not pyrolysis.
>>>   I am not sure whether the topic is appropriate for “gasification” either,
>>> since that list seems to want gases for engines, not liquids.
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>
>
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