[Terrapreta] Net Present Value and Net Future Value ofTPBenefits

[Sean K. Barry]

Hi Richard, et. al.

Attempting pyrolysis in the "semi-open" to make some charcoal of biomass and complete combustion of biomass differ in an important way.  The limited oxygen in a pyrolysis reaction can promote the production and emission of Methane-CH4 (a significant and potent GHG), whereas in complete combustion without the limit on oxygen, the biomass fuel is reduced to ash and complete combustion products (CO2 and H2O), with very little or no Methane-CH4.

With Methane-CH4 even at a mere 2-3% component (volume/volume) of the "producer gas", because of its potency as a GHG, releasing it will do more damage to the atmospheric concentration of GHGs and the GHG warming potential than the improvement that could be had by sequestering most of the remaining carbon from the biomass.  The damage from CH4 emissions can wipe out the advantage from sequestering the highest yield of charcoal (~30-40%) by weight.

The implement that is used to make charcoal in situ CANNOT release Methane-CH4.  The process must use it or flare it at the very least.

Regards,

SKB


  ----- Original Message ----- 
  From: Richard Haard<mailto:richrd at nas.com> 
  To: Edward Someus<mailto:edward at terrenum.net> 
  Cc: sean.barry at juno.com<mailto:sean.barry at juno.com> ; kchisholm at ca.inter.net<mailto:kchisholm at ca.inter.net> ; folke at holon.se<mailto:folke at holon.se> ; tjones at nas.com<mailto:tjones at nas.com> ; anaturalresource at gmail.com<mailto:anaturalresource at gmail.com> ; friendsofthetrees at yahoo.com<mailto:friendsofthetrees at yahoo.com> ; terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org> ; hans at riseup.net<mailto:hans at riseup.net> 
  Sent: Sunday, March 23, 2008 2:16 PM
  Subject: Re: [Terrapreta] Net Present Value and Net Future Value ofTPBenefits


  Edward - Are you comparing 'semi open, "simple" home made to industrial appliances or to burning of forest debris/ agricultural waste? It seems for the subsistence farmers of the humid tropics slash and char offers a reduction in net emissions even with simple methods so long as the biomass is carbonized, even partially. In addition, use of biomass as compost or letting decompose on ground will result in conversion of 100% to atmospheric form. The challenge is to design an implement  and distribute the appliance that can be economically used on a scale that is significant where biomass either cannot be transported or is not economic to do so. In urbanized air quality controlled  areas an air quality controlled implement is appropriate, but in rural areas where debris is burned anyway then low tech pyrolysis would result in a net permanent reduction of emissions.  


  Further, the use of an appliance that requires an investment and maintenance would be incentive to recover cash value of charcoal as fuel and at small scale as yet economic return from carbon buyback is not significant. This is what has me thinking that a low tech solution in or near the farmers field that results in a partial charred/compost-able product would yield a higher level of sequestration. 


  Please critique this viewpoint. For example, can you conclude charcoal produced in this manor has lesser value in agriculture than converting forest and agricultural debris to ash?


  Thank you 



  Rich H

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