Monday, 14 September 2009
TERRA PRETA – CARBON GOLD & CRABON CAPTURE
When plants grow they absorb carbon dioxide from the atmosphere. Under the normal carbon cycle when plants die they either rot or are burnt and the carbon they absorbed is returned to the atmosphere but although this is better than using fossil fuels for compost or heating/light, the process does not remove carbon from the atmosphere. The same applies to Bio fuel. The crops from which bio fuels are made take carbon dioxide out of the atmosphere while they are growing, but as soon as that bio fuel is used, the carbon is returned to the atmosphere through emissions. If, instead, waste biomass is turned into Biochar, it can be buried in the ground, locking in the carbon for hundreds or even thousands of years and have a positive impact on crop outputs.
I recently went to see a pilot system of making Biochar. The Biochar in this case was small branches that would normally be burnt or used for wood chippings. The project I looked at uses a sealed system so the gasses from the wood actually burn the wood, and 90% of the carbon is still locked in the Biochar.
But what then do we do with this material?
Scientists have known for years that adding Biochar could improve soil fertility. The early Amazonian Indians introduced Biochar to their soil over 3,000 years ago, forming the Terra Preta, black soil which remains fertile to this day. It is only recently that the reasons why this happened have been understood. Biochar is extremely porous; the surface is like a sponge. This encourages the growth of micro-organisms which produce enzymes that release the mineral ions trapped by the heat stabilized plant resins in the charcoal and make it available to the root hairs of the plant as nutrients. Furthermore, the resins within the charcoal act like an ion exchange resin, absorbing traces of mineral ions onto the charcoal particle surfaces from the rain water, and trapping it within the charcoal’s molecular structure. The trace minerals always present in rainwater actually act as a fertilizer - providing the nutrients needed by the crops, year after year.
Or as Johannes Lehmann - Department of Crop and Soil Sciences, Cornell University, Ithaca, New York, U.S.A said, “Important lessons can be learned from Terra Preta about development of civilization in the Amazon, basic functioning of soils, carbon sequestration, and sustainable land use”. I especially liked that last point, ‘sustainable land use’.
So we have a win-win situation, we create Biochar, locking the C02 away, and also create a proven fertiliser.
The systems to enable this are totally unsophisticated, as you can see. The materials are cheap and easy to obtain, a few building blocks, a sheet of metal and some oil drums. In the retort you can see in my photo’s the gas tight seal was obtained by a liberal application of Sussex clay, obtained from underfoot, while the trees that provided the wood grew around us. If you would like to know more about the Carbon-Gold project, please see HERE.
Genesis 1:12 The land produced vegetation: plants bearing seed according to their kinds and trees bearing fruit with seed in it according to their kinds. And God saw that it was good.
And not just good for beauty and food either it seems.
Posted by Fr. Peter Doodes at 08:04