Vind ik ook nogal 'wild'.
Wat ik wel graag zou weten of we geen kunstmatige fotosynthese kunnen laten gebeuren en zo een hoeveelheid 'CO2' op relatief 'natuurlijke' wijze laten verwerken...
Waarom het zo ver gaan zoeken?
Gewoon biomassa planten, in de pyrolyse-reactor steken, de energie ervan gebruiken en de biochar in de bodem vermengen. Dat hebt ge een koolstof-negatief energie-systeem dat nog bodems verbetert ook. Ge kunt daar zelfs het hongerprobleem in de wereld mee oplossen.
Die koolstofcaptering en -opslagmethode wordt "biochar" of "agrichar" genoemd en heeft een behoorlijk potentieel (ge kunt er namelijk *alle* antropogene CO2 emissies van een heel jaar mee capteren, en zelfs meer - als ge dat volhoudt, kunt ge atmosferische CO2-niveaus terugbrengen tot die van voor de Industriële Revolutie):
Terrestrial Carbon Sequestration with Biochar: A Preliminary Assessment of its Global Potential
AU: * Amonette, J
EM:
[email protected]
AF: Pacific Northwest National Laboratory, 902 Battelle Blvd., K8-96, Richland, WA 99354, United States
AU: Lehmann, J
EM:
[email protected]
AF: Cornell University, Department of Crop and Soil Sciences 909 Bradfield Hall, Ithaca, NY 14853, United States
AU: Joseph, S
EM:
[email protected]
AF: University of New South Wales, School of Materials Science and Engineering, 5 Kenneth Avenue, Saratoga, NSW 2251, Australia
AB:
Biochar technology involves the capture of CO2 from the atmosphere by photosynthesis and its ultimate conversion to biochar by pyrolysis. Energy is obtained during the pyrolysis process and the charcoal, or biochar, which is considerably more stable than biomass, may then be incorporated into agricultural lands where it serves to increase the nutrient- and water-holding capacity of soil.
With an estimated half-life in soil on the order of centuries to millenia, biochar offers a way of safely storing C for long periods of time while enhancing the productivity of terrestrial ecosystems. Moreover, biochar technology, like other biomass conversion approaches that include C sequestration options, offers a way to decrease the levels of CO2 in the atmosphere.
That is, biochar technology is one of the few inherently "carbon-negative" sources of energy. These positive attributes are of little consequence, however, if the total contribution to sequestration is small compared to the need. In this paper, we provide a preliminary assessment of the potential contribution of biochar technology to the mitigation of climate change, and identify some research needs.
Currently, the atmospheric C levels are increasing by about 4.1 Gt/yr, with 7.2 Gt/yr being put into the atmosphere by fossil fuel combustion and cement production, and 3.1 Gt/yr being removed from the atmosphere by the ocean (2.2 Gt/yr) and terrestrial processes (0.9 Gt/yr). The uptake by terrestrial processes can be increased significantly by management of the 60.6 Gt/yr of biomass C that is fixed by photosynthesis (i.e., net primary productivity), of which 59 Gt/yr is decomposed and 1.6 Gt/yr combusted.
Biomass pyrolysis converts about 50% of the biomass C to char. Of the other 50% that is converted to bio-oil and bio-gas, the net energy production is about 62% efficient. Thus, pyrolysis of 1 Gt of biomass C would provide energy equivalent to about 0.3 Gt of fossil C and could be used to offset that amount of fossil C, while sequestering 0.5 Gt as biochar. Of the 60.6 Gt/yr of biomass that is fixed in usable form, we estimate that perhaps 10% of it (6.1 Gt/yr) could become available in one form or another (crop and forestry residues, and animal waste) for pyrolysis.
This level of pyrolysis would offset 1.8 Gt/yr of fossil C, and sequester 3.0 Gt/yr as biochar, enough to halt the increase and actually decrease the level of atmospheric C by 0.7 Gt/yr.
Even at half this level (i.e., 5% of annually fixed biomass), pyrolysis would be sufficient to decrease the global C cycle imbalance by 2.4 Gt/yr and in combination with other sequestration options help to achieve the minimum goal of C neutrality.
Clearly, the potential contribution of biochar technology is large, perhaps large enough to mitigate climate change alone. However, this preliminary assessment is tempered by several unknowns. Research is needed to further define the impacts of biochar amendments on soil biota, productivity, and greenhouse gas production. For example, there is some evidence that N2O and CH4 production is decreased by biochar amendments, but the mechanisms responsible are unknown. The impact of different types of biochar and pyrolysis conditions also needs to be determined. Lastly, total accounting for greenhouse gas emissions coupled with economic analyses to determine the economic potential of the technology under various scenarios is essential.
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1630 Impacts of global change (1225)
DE: 1631 Land/atmosphere interactions (1218, 1843, 3322)
DE: 1699 General or miscellaneous
SC: Union [U]
MN: 2007 Fall Meeting
http://www.agu.org/cgi-bin/SFgate/SFgate?&listenv=table&multiple=1&range=1&directget=1&application=fm07&database=%2Fdata%2Fepubs%2Fwais%2Findexes%2Ffm07%2 Ffm07&maxhits=200&=%22U42A-06%22
Omwille van dit grote potentieel, en de zeer haalbare en efficiënte aard van dit concept, heeft James Hansen het opgenomen in zijn 350.