[Terrapreta] Sustained Biochar
Adriana Downie
adriana at bestenergies.com.au
Wed Aug 29 19:34:31 EDT 2007
Sean,
As those of you on the list who have visited BEST will know, even on our
small (18L) batch pyrolysis reactor that we use for experimental work we
flare the syngas that is produced. I think this is the much preferred
option for production of char for research purposes and it doesn't
propagate bad practices that are promoted and therefore replicated
around the world by everyone in there backyard.
Also, I don't think it is worthwhile doing research on char that the
process conditions (heating rate, residence time, final temperture etc)
are not well know, as we have seen huge impacts in agronomic response to
chars made differently. Therefore you need a reactor that it is not only
possible to measure but also control these things. You won't get this in
a mound.
Adriana.
-----Original Message-----
From: Sean K. Barry [mailto:sean.barry at juno.com]
Sent: Wednesday, 29 August 2007 12:25 AM
To: 'Richard Haard'; Adriana Downie
Cc: terrapreta at bioenergylists.org
Subject: Re: [Terrapreta] Sustained Biochar
Good Morning Richard, Adriana,
Yes, Richard, I think that on the grand scheme of things, to make lots
of charcoal, so as to sequester lots of carbon into "Neo Terra Preta"
soils, that I am technically right that open charcoal kilns and venting
producer gas just will NOT work. The pollution impact
(GHG and particulates) would be just too devastating to the cause.
On the other hand, Adriana, Richard is very practically correct. Some
one has said this before too, that when we are talking about making a
small amount of charcoal to do research on the agricultural benefits of
charcoal amendments to a small plot of soil, that we should not be too
concerned about venting the off gases from making charcoal in a simple
"open air" kiln. If it were an absolute requirement that charcoal not
be made that way, then Richard, and many others who have embarked on
doing valuable TP research would never have done it. This would not do.
Nor, is it worth chastising anyone now who makes small amounts charcoal
however they can, in an attempt at doing TP research.
Regards,
SKB
----- Original Message -----
From: Adriana Downie <mailto:adriana at bestenergies.com.au>
To: 'Richard Haard' <mailto:richrd at nas.com>
Cc: terrapreta at bioenergylists.org
Sent: Tuesday, August 28, 2007 12:47 AM
Subject: Re: [Terrapreta] Sustained Biochar
Rich,
Please go back and read Seans post. You are better to burn to CO2 than
pyrolysis and release syngas. I think that promoting small scale
pyrolysis is going backward and gives fuel to the sceptics.
Adriana.
-----Original Message-----
From: Richard Haard [mailto:richrd at nas.com]
Sent: Tuesday, 28 August 2007 3:21 PM
To: Adriana Downie
Subject: Re: [Terrapreta] Sustained Biochar
Adriana
Yes but ---- When neighbors on both sides are burning debris and logging
operations on ridge 3500 feet above us are burning slash what is the big
deal with making some charcoal for your own curiosity on the effects of
charcoal in your garden and to make a convert who in the long term may
help to educate others about the benefits of sequestering carbon on a
larger scale if and when such charcoal and charcoal making equipment
becomes available on the market.
Rich H
On Aug 27, 2007, at 10:10 PM, Adriana Downie wrote:
Thanks Sean,
This is a very important point that really needs to be well understood.
Those who are making char in a 44 gallon drum in the back yard and
putting it on the vege garden are not doing the planet any favours. What
is more, they are not doing themselves any favours either because not
only do traditional methods have Greenhouse effects which far out weigh
the benefits of sequestering char in soil they also have severe human
health impacts which far out weigh any social benefit from improved
agricultural yields. Particulate emissions are often the overwhelming
detrimental effect when environmental LCAs are done, it is essential to
manage these if this technology is to be of any benefit. No good saving
the planet from global warming if in turn we give everyone respiratory
diseases.
Regards,
Adriana Downie
BEST Energies Australia
-----Original Message-----
From: Sean K. Barry [mailto:sean.barry at juno.com]
Sent: Tuesday, 28 August 2007 2:46 PM
To: Robert Klein
Cc: terrapreta
Subject: Re: [Terrapreta] Sustained Biochar
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 <mailto:arclein at yahoo.com>
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-i
n-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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