[Terrapreta] ? GHG emissions from Biomass Combustion ?

[Sean K. Barry]

Hi Erich , Tony,

There is an important distinction that needs to be made about what is the real problem with green house gases (GHGs) in the atmosphere.  Increasing concentration are the problem.  Biomass can produce gases from combustion which are classified as GHGs.  However (and this is a critically important distinction), burning biomass CANNOT increase GHG concentrations in the atmosphere!  The cellulose, hemi-cellulose, lignin, sugars, and starch, that are in biomass are made via photosynthesis when the plants are growing and taking CO2 and H2O from the Biosphere.  Releasing those gases back into the atmosphere, there is no net gain.

Fossil carbon in fossil fuels, though, like liquid petroleum, solid coal, and natural gas is ~300 million year old carbon which has not been in the atmosphere for ~300 million years.  EMISSIONS ONLY FROM BURNING FOSSIL CARBON FUELS OR DECOMPOSTION OF FOSSIL CARBON DERIVATIVES will increase the relative concentrations of GHG in the atmosphere.

There is one caveat about this, though. The emissions of Methane-CH4 or Nitrous oxide-N2O from products made with biomass reactants can be a significant contributing factor to Global Warming or Global Climate Change.  CH4 is 23 times more potent as a GHG and N2O is 296 times more potent than CO2 is at "re-radiating" infrared radiation (heat) back down from the atmosphere to the surface of the Earth (where the heat came from).

Open burning of biomass releases mostly CO2 and H2O (complete combustion products).  These are both GHG, but again, they do not increase atmospheric concentration of these gases.  If biomass is heated in an oxygen deprived environment (like an enclosed kiln), however, then it can release Hydrogen gas-H2, Carbon Monoxide-CO (neither are GHG), and Methane-CH4 (a powerful GHG).  The concentration of Methane-CH4 in the "producer gas" coming from such a reaction will be only 2-3%.  At 3%, the GHG warming effect of that Methane-CH4 outweighs all of the CO2 or H2O that were produced in the reaction.

So, kiln users must "Flare" or otherwise burn or use the CH4 fuel gas component exiting from their devices.

Regards,

SKB
  ----- Original Message ----- 
  From: Shengar at aol.com<mailto:Shengar at aol.com> 
  To: terrapreta at bioenergylists.org<mailto:terrapreta at bioenergylists.org> 
  Sent: Sunday, March 09, 2008 10:38 PM
  Subject: [Terrapreta] ? GHG emissions from Biomass Combustion ?


  Hi All, 

  Could anyone provide the figures Tony Lovell is asking for below;



  "Erich

  Thanks you for sharing our work with your colleagues at TP. 

  Would you or any of your colleagues be able to assist me with finding some information?

  I am looking for general parameters on how much of what GHG’s are produced due to the combustion of biomass. In particular if we were to combust say 1,000kgs dry matter of switchgrass or similar material how much CO2, CH4, CO, etc etc would be released. 

  Any assistance you can provide is greatly appreciated.

  Take care,

  Tony Lovell

   Soil Carbon (Australia) Pty Ltd

  PO Box 157, BOND UNIVERSITY QLD 4229

  Suite 102, 20 Lake Orr Drive, VARSITY LAKES QLD 4227

  Ph: +61 (0)7 5553 7900 Fax: +61 (0)7 5553 7999 Mob: +61 (0)418 730340
  Email: tonyl at soilcarbon.com.au<mailto:tonyl at soilcarbon.com.au>







  Thanks 

  Erich






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