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 <[email protected]> wrote: > Dear Ron > > Quoting "Ronal W. Larson" <[email protected]>: > > 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 <[email protected]> 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: [email protected] [mailto:[email protected]] 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 <[email protected]> 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. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >> > > > _______________________________________________ > Gasification mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > http://lists.bioenergylists.org/mailman/listinfo/gasification_lists. > bioenergylists.org > > for more Gasifiers, News and Information see our web site: > http://gasifiers.bioenergylists.org/ >
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