Ken I disagree, with respect. Transport below the mixed layer is a key limitation on OIF, cited in most evaluation of the technology. Forcing this export seems entirely reasonable. Various passive pump designs (eg from Salter), make this a possibility worthy of detailed modelling. Upwards pumping may be a different matter, but down welling at least seems worth more detailed consideration - esp in conjunction with OIF.
Is there a fully-costed proposal proving that passive down welling with OIF is non-viable? Without that, I'd personally be loathe to rule it out. A On Jan 17, 2013 6:09 PM, "Ken Caldeira" <[email protected]> wrote: > We should pay attention to Chris Vivian's email in which he referred to > several papers indicating that ocean pumps are not an effective method of > drawing down CO2 from the atmosphere. > > The speculative discussion in this thread has moved far away from the > scientific understanding of the situation. > > _______________ > Ken Caldeira > > Carnegie Institution for Science > Dept of Global Ecology > 260 Panama Street, Stanford, CA 94305 USA > +1 650 704 7212 [email protected] > http://dge.stanford.edu/labs/caldeiralab @kencaldeira > > *Caldeira Lab is hiring postdoctoral researchers.* > *http://dge.stanford.edu/labs/caldeiralab/Caldeira_employment.html* > > Our YouTube videos<http://www.youtube.com/user/CarnegieGlobEcology/videos> > > > On Thu, Jan 17, 2013 at 9:47 AM, William H. Calvin < > [email protected]> wrote: > >> >> >> >> Hello all, >> >> Thinks look different if one uses push-pump pumps rather than simply >> upwelling of nutrients. The upwelled DIC becomes insignificant compared to >> the DOC pushed down. Some of you may recall this argument from my GLOBAL >> FEVER book from the Univ of Chicago Press, but the following is an excerpt >> from my THE GREAT CO2 CLEANUP, chapter six: >> >> Plowing Under a Carbon-fixing Crop >> >> To avoid competing with the world’s food production and supplies of fresh >> water, most sequestered carbon must come from new biomass grown in new >> places. Here I explore how paired ocean pumps might uplift nutrients and >> then sink the new organic carbon back into the ocean depths. >> >> Instead of sinking only the debris that is heavy enough to settle out, as >> in iron fertilization, we would be using bulk flow to sink the entire >> organic carbon soup of the wind-mixed layer (organisms plus the >> hundred-fold larger amounts of dissolved organic carbon) before its carbon >> reverts to CO2 and equilibrates with the atmosphere. >> >> The CO2 later produced in the depths by the sunken carbon soup will reach >> the surface 400-6,000 years later. Smearing it out over that period greatly >> reduces the damaging peaks in ocean acidification and global fever. >> >> ... >> >> If we fertilize via pumping up and sink nearby via bulk flow (a push-pull >> pump), we are essentially burying a carbon-fixing crop, much as farmers >> plow under a nitrogen-fixing cover crop of legumes to fertilize the soil. >> Instead of sinking only the debris that is heavy enough, we would be >> sinking the entire organic carbon soup of the wind-mixed layer. >> >> Algaculture minimizes respiration CO2 from higher up the food chain and >> so allows a preliminary estimate of the size of our undertaking. Suppose >> that a midrange 50 g (as dry weight) of algae can be grown each day under a >> square meter of sunlit surface, and that half is carbon. Thus it takes >> about 10-4 m2 to grow 1 gC each year. To produce our 30 GtC/yr drawdown >> would require 30 x 10+11 m2 (0.8% of the ocean surface, about the size of >> the Caribbean). >> >> But because we pump the surface waters down, not dried algae, we would >> also be sinking the entire organic carbon soup of the wind-mixed surface >> layer: the carbon in living cells plus the hundred-fold larger amounts in >> the surface DOC. Thus the plankton plantations might require only 30 x 10+9 >> m2 (closer to the size of Lake Michigan). >> >> The space requirement will be more because downpumps will not capture all >> of the new plankton; it might be less because the relevant algaculture >> focuses on oil-containing algal species and on harvesting a biofuel crop, >> not on plowing under the local species as quickly as possible. The ocean >> pipe spacing, and the volume pumped down, will depend on the outflow needed >> to optimize the organic carbon production. [The chemostat calculation FYI.] >> Only field trials are likely to provide a better estimate for the needed >> size of sink-on-the-spot plankton plantations, pump numbers, and project >> costs. >> >> Though ocean fertilization is usually proposed for low productivity >> regions where iron is the limiting nutrient, another strategy is to boost >> the shoulder seasons in regions of seasonally high ocean productivity. For >> example, ocean primary productivity northeast of Iceland drops to half by >> June as the nutrients upwelled by winter winds are depleted. Continuing >> production then depends on recycling nutrients within the wind-mixed layer. >> However, to the southwest of Iceland, productivity stays high all summer. >> >> Because not all of the new plankton will be successfully captured and >> sunk, fertilization will stimulate the marine food chain locally. Most >> major fisheries have declined in recent decades and, even where sustainable >> harvesting is practiced, it still results in fish biomass 73% below natural >> levels. At least for fish of harvestable size, there is niche space going >> unused. >> >> Locating the new plankton plantations over the outer continental shelves >> is more likely to supply a complete niche for many fish species, whereas >> deep-water plantations will lack variety. (The main commercial catch in >> deep water is tuna.) Also, down-pumping near the shelf edge would deposit >> the organic carbon in the bottom’s offshore "undertow" stream, carrying it >> over the cliff onto the Continental Slope into deeper ocean. >> >> Note that pumps would be tethered to the bottom so that the ocean >> currents are always creating a plume downstream: a plume of fertilizer near >> the surface and a second plume of carbon soup in the depths. (Pumping up >> from a different depth than pumping down will prevent the interaction that >> characterizes the oceanographers’ box models.) While the water might come >> back around in a thousand years, the plumes for the clean-up will only be >> about twenty years long and well diluted by that time. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "geoengineering" group. >> To view this discussion on the web visit >> https://groups.google.com/d/msg/geoengineering/-/gD00bcFFIvIJ. >> >> To post to this group, send email to [email protected]. >> To unsubscribe from this group, send email to >> [email protected]. >> For more options, visit this group at >> http://groups.google.com/group/geoengineering?hl=en. >> > > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]. > For more options, visit this group at > http://groups.google.com/group/geoengineering?hl=en. > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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