[Terrapreta] One Tonne of charcoal = X?? amount of sequestered GHGs

[Sean K. Barry]

Hi Michael,

You ask, "Can any one who is clever at sums, tell me how much GHG is sequestered per tonne of Charcoal?"

You have got to know, that I am going to try and answer that. 

I've think I've read from the work of Dr. Michael Antal, Jr., from the University of Hawaii, that charcoal can be up to 93-95% pure carbon in the charcoal and maybe only as much as 80some%, the rest being carbon containing volatile matter (but, which can apparently be decomposed by soil microorganisms over time) and/or ash.

So, conservatively a metric ton of charcoal (dominated by 80% pure carbon), probably then amounts to ~800 kg of carbon.  The most prevalent carbon containing gas, which enters the atmosphere from anthropogenic sources, is, I think, carbon dioxide (CO2).  The sum 12+16+16 = the atomic weight of one carbon plus two oxygen atoms (or the weight of a mole number of CO2 molecules, measured in grams).  This is 44 grams per mole, 12 parts carbon, and 32 parts oxygen.  So, 800 kg of pure carbon is equivalent to ~2933 (= 800*44/12) kilograms of CO2 gas in the atmosphere.

The IPCC, the Kyoto Protocol, and others always talk about "carbon equivalent" amounts, though.  The oft quoted 6Gt per year from anthropogenic sources means 6 billion tons of just the weight of carbon atoms put into the atmosphere.  Those atoms are parts of a larger weight (like *44/12) of molecular gaseous molecules that contain carbon (CO2, CH4, etc).

Additionally, some very potent GHG do not even contain one single atom of carbon (e.g. nitrous oxide (N2O), for instance).  It still is measured in what are called "carbon equivalents".  The number of molecules in a volume of nitrous oxide (N2O) gas has an effect on the atmosphere, which is equivalent to that from a volume of gas containing 296 times the same number of carbon containing molecules. 

I hope this helps.

SKB
-------------- next part --------------
An HTML attachment was scrubbed...
URL: /pipermail/terrapreta_bioenergylists.org/attachments/20070602/b297f689/attachment.html