[Terrapreta] Sustained Biochar

[Sean K. Barry]

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<mailto: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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