[Terrapreta] Sustained Biochar

Tue Aug 28 01:06:36 EDT 2007

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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