[Terrapreta] Sustained Biochar
Erin Rasmussen
erin at trmiles.com
Tue Aug 28 14:39:30 EDT 2007
Hello,
I've been reading, and re-reading this thread trying to understand it, and
I'm really confused. Will one of you, or a couple of you participating
please write a quick summary of the argument for a more average reader?
Other things that confuse me about the argument:
Why would a commercial producer or charcoal use an open pit method?
Charcoal doesn't seem to be produced that way currently. Surely high volume
production of charcoal as a soil amendment isn't going to be radically
different from production for barbecues, or is that a faulty assumption on
my part?
So I guess I would like to know how we calculate the break-even point. If
terrapreta really works as well as it seems to in my extremely limited test
batches. How do we calculate the total cost of "local" charcoal production,
so that we can compare that to the cost of commercially produced
fertilizers, hauling, and transport costs (carbon emissions). For example,
I live in Portland, Oregon and my choices at the garden center are charcoal
from Northern California and Miracle Gro "Organic". Which one is a better
choice?
Erin Rasmussen
_____
From: terrapreta-bounces at bioenergylists.org
[mailto:terrapreta-bounces at bioenergylists.org] On Behalf Of Gerald Van
Koeverden
Sent: Tuesday, August 28, 2007 9:22 AM
To: Sean K. Barry
Cc: terrapreta
Subject: Re: [Terrapreta] Sustained Biochar
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: <mailto:vnkvrdn at yahoo.ca> Gerald Van Koeverden
To: <mailto:sean.barry at juno.com> Sean K. Barry
Cc: <mailto:arclein at yahoo.com> Robert Klein ;
<mailto:terrapreta at bioenergylists.org> 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>
http://www.mpg.de/english/illustrationsDocumentation/multimedia/mpResearch/2
006/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: <mailto:vnkvrdn at yahoo.ca> Gerald Van Koeverden
To: <mailto:sean.barry at juno.com> Sean K. Barry
Cc: <mailto:arclein at yahoo.com> Robert Klein ;
<mailto:terrapreta at bioenergylists.org> 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: <mailto:arclein at yahoo.com> Robert Klein
To: <mailto:terrapreta at bioenergylists.org> 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>
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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