[Terrapreta] ch4 vs co2 issues in biochar sequestion

[jim mason]

one of my pet projects of late is to assemble a chart of partial gas
outputs from all "thermal" decomposition of biomass processes- from
atmospheric temps of rotting, through anerobic digestion, through
pyrolysis, through gasification and to full combustion.

as you all know, the different temps at each of these "named" points
along the spectrum optimize the production of different gasses, for
different end uses.  the approximate progression of selected gases and
products is ch4, char, h2, co and co2.

it is realized that the presence and relevance of bacteria and other
inputs (oxygen, etc) are changing variables across this thermal
spectrum.  but nonetheless, i think there is an opportunity to
meaningfully relate all the biomass "decomposition" processes into
something more easily grasped by the larger audience.


another important point in such a chart would be noting that the lower
temp decomposition processes optimize ch4 (methane) production, a much
worse green house gas than co2.  this seems to me a very important
part of the terra preta argument.

letting the energy in and components of carbohydrates complete their
cycle back to the atmosphere through open to atmospheric rotting or
compost, without ch4 collection, is a very bad from a ghg perspective.
 there might be more traction on the warming problem through an ag,
trash intervention to prevent ch4 emission, using terra preta and
methane capped landfills, than the effects of co2 prevention from raw
c sequestration also provided by terra preta.

or in other words, have we figured out the relative importance of ch4
vs co2 emission prevention that terra preta offers.  both are
happening.  it might be that the effects of the former are more
important than the later, or equally important, or fractionally
important.

to figure out if there is any substance to this speculation, i need
numbers on the gas emissions from the lower temp biomass composition
processes.  what are the ratios of ch4 to co2 under different low temp
decompotion conditions?

if anyone can help me find these for above and below ground atm
rotting, as well as active digestion, it would be greatly appreciated.
 i have good numbers from pyrolysis temps up through full combustion.
but i can't find the same for below pyrolysis temps.

jim