Hi all, thanks for the useful replies, I think I've got my head around the science side of things.
Coming back to the biochar side of things, a couple of things;
Biochar is a proven improvement to soil structure as was observed in the Amazon basin. It works by absorbing both water and nutrients, giving much higher crop yields. It offers a structure for microbes to prosper.
Production of biochar through pyrolysis yields both gases that can be burned as well as biochar that can be used to improve soil structure.
Here in Oz there's a plant that uses the energy released by burning wood gas to produce :
-as well as cause more pyrolysis hence more gas, more energy
-the very useful by product is biochar.
It is by far the most simple, feasible to improve our current predicament. Granted, growing more 1000 year old forests is preferable, the drawback is it takes a 1000 yrs............
Here's a plan for the anila stove http://www.bioenergylists.org/files/images/Biochar_Anila_s_Page_13.preview.jpg
that produces biochar, which is part of a secondary process in the double wall of the burner, quite ingenious.
Got some interesting sites on biochar if anyone is interested http://terrapreta.bioenergylists.org/taxonomy/term/253 http://www.theoildrum.com/node/4522
this one is particularly good, watch the you tube clips