[Terrapreta] Sustained Biochar
Gerald Van Koeverden
vnkvrdn at yahoo.ca
Tue Aug 28 12:21:39 EDT 2007
Sean,
Yes, I understand that. We have an interpretation problem. When I
wrote that "He produces materials that are 100% charcoal from any
source of biomass in his steam cooker", all I meant was that the
residue produced is 100% charcoal, not "oil" as you claimed to be the
main product of this process. You are right that oil is the main
product of previous attempts to steam heat biomass completely.
However, this particular process runs at 200C instead of 350-400C,
and charcoal seems to be an intermediate product that can be obtained
by arresting the biomass de-generation process midway.
You are certainly right that there are probably other chemical
products of the exothermic reaction which are vaporized in the
steam. That's why I asked the question in the first place, about the
noxious by-products of hydrothermal carbonization, since it had never
occurred to me to consider this question before your previous message
on methane and nitrous oxide.
Maybe the Max Plank researchers at this initial stage in the
development of the process, still haven't asked themselves this
question about gaseous by-products? Whatever, since it is a closed
system, and the only escape hatch is the relief valve on the boiler
(necessary in order to keep the temperature down to 200C when the
biomass starts to go exothermic), such potential pollutants (or maybe
even commercial by-products?) can be dealt at this point in the
process...
Gerrit
On 28-Aug-07, at 11:17 AM, Sean K. Barry wrote:
> Hi Gerrit,
>
> All plant biomass is things like sugars, cellulose, hemi-cellulose,
> and lignin, basically carbohydrates. The ratio of # of atoms of
> carbon-C, hydrogen-H, and oxygen-O; C:H:O, is very close to
> ~1:2:1, as all carbohydrates are made up of multiples of CH2O
> molecular constructs.
>
> Charcoal on the other hand is 93-95% pure carbon. It does often
> times still contain some small amounts (5-7%) of combustible
> hydrocarbons and carbohydrates. Usually this is called the
> volatile matter content of the charcoal. The C:H:O ratio in
> charcoal then is something more like ~95:10:5.
>
> So, where did all the H2O part of the CH2O carbohydrates go? ...
> from within a "sealed" and pressurized vessel? The hydrogen and
> oxygen atoms cannot be transmuted into carbon atoms by this
> chemical process. The answer is, that the hydrogen an oxygen is
> all still there. It would not surprise me, either, if Dr.
> Antonietti's reactor did not vent some gases (perhaps CO2, H2, CO,
> N2, CH4, and O2?) upon opening.
>
> The mass of a single carbon-C atom is 12 atomic units, 1 au for a
> hydrogen-H atom, and 16 au for an oxygen-O atom. So, in
> carbohydrates, where ratio of # of atoms, C:H:O is approximately
> ~1:2:1, then then mass ratio is 12:2:16. Then carbon-C makes up,
> at most ~40% (12/(12+2+16) = 0.40) of the total mass of any un-
> pyrolyzed, raw, biomass. It is NEVER possible to convert 100% of
> the mass of any plant material (biomass) entirely into carbon. 40%
> is the maximum achievable yield of fixed carbon (on a weight/weight
> basis) from the conversion of any biomass, regardless of the method
> used for conversion. Because charcoal is not entirely pure carbon
> (it contains volatile matter), then the actual maximum yield of
> charcoal is even less, perhaps 35%.
>
> You might read some of the materials presented on this site my Dr.
> Michael J. Antal from the University of Hawaii. He has great
> experience with conversion of biomass into charcoal and he is also
> Bio-chemist ro a Bio-chemical engineering professor, so he
> understands and has written much about this subject (charcoal yield
> from conversion of biomass).
>
> Regards,
>
> SKB
>
>
> ----- Original Message -----
> From: Gerald Van Koeverden
> To: Sean K. Barry
> Cc: Robert Klein ; terrapreta
> Sent: Tuesday, August 28, 2007 6:28 AM
> Subject: Re: [Terrapreta] Sustained Biochar
>
> Dr. Markus Antonietti (Max Plank Institute) writes it's just a
> matter of knowing when to stop the carbonization process. He
> produces materials that are 100% charcoal from any source of
> biomass in his steam cooker. I don't see how it would be possible
> to get a higher yield of charcoal through any other process.
>>
>
>> http://www.mpg.de/english/illustrationsDocumentation/multimedia/
>> mpResearch/2006/heft03/3_06MPR_20_25.pdf
>
> Gerrit
>
>
> On 28-Aug-07, at 1:36 AM, Sean K. Barry wrote:
>
>> Hi Gerrit,
>>
>> I have not heard or read specifically of what you call
>> "hydrothermal carbonization". However, there is a process I read
>> about on Wikipedia once, and in some referenced articles and
>> texts, which might be similar? It is called "molecular de-
>> polymerization" (look it up!) and it occurs as a chemical
>> reaction in biomass, which has been ground up and mixed with
>> water, and brought to a high pressure and high temperature, in a
>> sealed vessel, for a short period of time. The result of the
>> reaction is to turn the "biomass/water soup" in a refine-able bio-
>> oil. There is no release of any "producer gas" with this
>> reaction, I don't think.
>>
>> It is certainly possible that any chemical reaction which occurs
>> in a "sealed" vessel will not produce any gas phase reaction
>> products, especially if its done under pressure. Even the
>> strictly thermo-chemical process of pyrolysis can be done in such
>> a way that it does not release gases (see the work of Brown et,
>> al., at the University of Iowa and NREL, on the production of
>> pyrolytic bio-oils).
>>
>> The problem with using these processes that do not produce gases,
>> as I see it, for Terra Preta purposes, is that they also do not
>> produce large amounts of charcoal either. The destructive
>> distillation of biomass which occurs in "hydrothermal
>> carbonization" and "molecular de-polymerization" reactions can
>> reduce a chunk of lignin/hemi-cellulose (wood) into a pool of
>> black oil, without releasing any gases. But, if the biomass
>> moisture content is low enough (<20% m.c. dry basis) to produce
>> charcoal during pyrolysis, then "producer gas" will also be
>> released in the reaction.
>>
>> So, I would guess that "hydrothermal carbonization" might be an
>> easier way to convert biomass into more usable energy forms (a
>> refine-able bio-oil), but it won't be able to make charcoal
>> from biomass for use in amending soil.
>>
>> Regards,
>>
>> SKB
>> ----- Original Message -----
>> From: Gerald Van Koeverden
>> To: Sean K. Barry
>> Cc: Robert Klein ; terrapreta
>> Sent: Tuesday, August 28, 2007 12:06 AM
>> Subject: Re: [Terrapreta] Sustained Biochar
>>
>> Sean,
>>
>> Do you have any idea of the production of gases in the process of
>> hydrothermal carbonization which takes place at about 200C? I
>> have just assumed that none would be produced in this process.
>>
>> Gerrit
>>
>> On 28-Aug-07, at 12:45 AM, Sean K. Barry wrote:
>>
>>> Hi Robert,
>>>
>>> I don't know where you get the information for your postings. It
>>> seems sheer speculation. Is it? Isn't it?
>>>
>>> Making charcoal in earthen mounds will NOT reduce the global
>>> warming effect of green house gases (GHG). This happens because
>>> all of the charcoal (~93-95% carbon) that could be sequestered
>>> into soil, rather than being released as CO2 (a complete
>>> combustion product and a GHG), still CANNOT reduce away the
>>> effect of releasing the even 2-3% methane (CH4), during the
>>> charcoal making process. Open air charcoal kilns will release
>>> more GHG and exacerbate the global warming problem. This will
>>> happen even with all the benefits that could be derived from
>>> burying the charcoal. You will get reduced atmospheric
>>> CO2, but also increased atmospheric methane (CH4), by making
>>> charcoal this way.
>>>
>>> This is a critically important fact. Ask any bio-chemist? It
>>> will not be disputed. Charcoal for "Neo Terra Preta" must be
>>> made in sealed reactor and the producer gas should not be
>>> released to the atmosphere like exhaust, or smoke.
>>>
>>> The producer gas from a pyrolysis of biomass reaction contains 1)
>>> complete combustion product gases; CO2, H2O, 2) combustible fuel
>>> gases; H2, CO, CH4, 3) inert + trace gases; N2, O2,
>>> Argon, etc., and 4) some suspended, vaporized, tars (longer chain
>>> hydrocarbons and carbohydrates, like ethane gas, methanol, and
>>> acetic acid. All together the "producer gas" can have an energy
>>> content of ~200-300 BTU/Nm^3). The higher BTU density gases come
>>> come from low temperature pyrolysis (with very limited oxygen and
>>> lots of added heat). These gases are rich in methane (CH4) and
>>> longer chain hydrocarbons.
>>>
>>> One molecule of methane (CH4) has a GHG equivalent effect the
>>> same as 62 molecules of CO2! This is a startling fact.
>>>
>>> If open air pyrolysis retains as much as 25% of the original
>>> carbon in the biomass, then 75% of all of the carbon from the
>>> biomass is expelled from the reactor into the producer gas, as
>>> part of both carbon monoxide (CO - ~20% of producer gas) and
>>> carbon dioxide (CO2 - ~10-15% of producer gas) gases. Burnt or
>>> simply released, it is still 75% of the carbon from the biomass
>>> goes into the atmosphere. Because of the potency of methane
>>> (CH4) as a GHG, it is far worse to release methane (CH4), than it
>>> is to burn it;
>>>
>>> CH4 + 2(O2) => CO2 + 2(H20)
>>>
>>> Rich BTU producer gas contains ~3% methane (CH4), so the producer
>>> gas contains only ~10-11 times as many carbon containing
>>> molecules as methane molecules (CH4), (~0.30-0.35/0.03) =
>>> ~10-11. The charcoal contains 1/3 the amount of carbon (25%/75%)
>>> as the gas; so the number carbon atoms in the charcoal compared
>>> to the number of methane (CH4) molecules is ONLY (((~0.30-0.35
>>> +0.03)/3)/0.03) = ~4:1.
>>>
>>> RELEASING THE METHANE contained in the producer gas (unburned),
>>> then has the same effect on the atmosphere as releasing 15 TIMES
>>> AS MUCH CARBON AS THERE IS IN ALL OF THE CHARCOAL YOU COULD
>>> POSSIBLY BURY (62/4 = ~15)!
>>>
>>> The point is then, that open air charcoal kilns CANNOT make
>>> charcoal fast enough without making the atmospheric GHG
>>> conditions worse even faster. It is absolutely imperative the
>>> charcoal making devices should be "sealed" and the producer gas
>>> should at minimum be "flared" off, or the fuels it contains
>>> completely combusted and the resultant energy used.
>>>
>>> Any simpler just make charcoal out in earthen kilns plan will
>>> poison the atmosphere even faster than doing nothing, so we might
>>> cook the planet well before we could realize any of the
>>> agricultural benefits of putting charcoal into the ground.
>>>
>>> Regards,
>>>
>>> SKB
>>>
>>>
>>> ----- Original Message -----
>>> From: Robert Klein
>>> To: terrapreta at bioenergylists.org
>>> Sent: Monday, August 27, 2007 3:15 PM
>>> Subject: [Terrapreta] Sustained Biochar
>>>
>>> I cannot help but think that the methods used to
>>> produce the black soils must be self sustaining and
>>> indigenous to the farm itself. I also see the use of
>>> fairly large pieces of charcoal that will be difficult
>>> to pulverize properly. Remember that grinding has a
>>> natural sizing limit, past which a great deal of
>>> effort is needed.
>>>
>>> Without question the use of corn stover to build
>>> natural earthen kilns is a great solution when we are
>>> relying on hand labor alone.
>>>
>>> See:http://globalwarming-arclein.blogspot.com/2007/07/carbonizing-
>>> corn-in-field.html
>>>
>>> We also can conclude that corn stover is the best
>>> available source of large volume biochar. It needs to
>>> be central to any program simply to ensure 100%
>>> coverage of the fields with sufficient biochar.
>>>
>>> Is there a way to do this in the field with equipment?
>>>
>>> Let us return first to best hand practice. From there
>>> we can speculate on how this can be made easier with
>>> power equipment.
>>>
>>> We do not know how the Indians in the Amazon did this
>>> but we certainly know how they grew corn everywhere
>>> else.
>>>
>>> In North America, they used a trinary system.
>>>
>>> That meant that they cleared a seed hill, likely two
>>> plus feet across, perhaps slightly raised, in which
>>> they planted several corn seeds and also several
>>> beans. These hills would have been at least two feet
>>> apart. this means that twenty five percent of the
>>> land was been cropped in this way. They also planted
>>> every few hills a few pumpkins. This provided ground
>>> cover for the seventy five percent of the land not
>>> been directly cropped.
>>>
>>> An interesting experiment would be to now grow alfalfa
>>> in between the hills in order to fix nitrogen and
>>> provide a late fall crop. It unfortunately would
>>> likely take too much water.
>>>
>>> This Indian system is ideal for hand work and for the
>>> production of terra preta by hand.
>>>
>>> In September,after the corn,beans, and pumpkins are
>>> picked, it is time to remove the drying corn stover
>>> and bean waste. The pumpkin waste will be trampled
>>> into the ground fairly easily by now.
>>>
>>> Hand pulling the stalks from one seed hill gives you a
>>> nice bundle to carry off the field to where a earthen
>>> beehive is built for the production of Terra preta.
>>>
>>> How do we accomplish the same result with the use
>>> equipment is a difficult question. Using a stone boat
>>> or wagon is obvious. A hydraulic grabber of some sort
>>> to pull the bunch associated with a hill would be very
>>> helpful. Tying the bundles would also be helpful.
>>>
>>> This would allow two workers to clear a larger field
>>> quite handily.
>>>
>>> After the earthen field stack is set up, the rest is
>>> fairly simple. A wagon full of biochar is taken to
>>> the field and each hill is replenished with biochar
>>> before planting. Still a lot of labor but much easier
>>> than the most basic system.
>>>
>>> To do this with row agriculture will mean the creation
>>> of some fairly complex lifting and baling machinery.
>>> At least we are on the right track.
>>>
>>>
>>>
>>>
>>>
>>>
>>> ____________________________________________________________________
>>> ________________
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>>
>>
>
>
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