Andrew: Quick answers:
1. Burning crop waste doesn't pencil out. It burns at low temperatures, is mostly cellulose and lignin. That's why farmers don't sell it to biofuel burners. But it has plenty of carbon and few nutrients. 2. There are no useful air capture technologies, and not likely to be any soon. The APS report about to appear spells out why: it's a huge energy sink. 3. There are not legal restrictions on dumping organic farm matter at sea. Industrial, yes, but with broad exceptions there, too. 4. In the deep ocean, hydrate deposits don't form from decaying matter. Farm waste, as the studies going on now off Monterey CA show, goes slowly into solution. It won't return to the air for at least millennia. The Strand & Benford calculations show it's cost efficient and carbon efficient. Gregory Benford On Fri, Sep 10, 2010 at 2:20 PM, Andrew Lockley <[email protected]>wrote: > Isn't the main problem with CROPS that you're burying something which is > flammable, at the same time that similar flammable materials are being dug > up elsewhere ? There seems little point collating and transporting all that > crop waste, then just throwing it into sea, when you could generate power > with it instead. > > Ironically it might be more efficient to use the electricity so generated > to power carbon air capture technologies. With a bit of luck there would > still be enough electricity left over to sell, even after you'd captured > more carbon than was in the original crop waste. > > A second problem is, as previously mentioned, the legal restriction on > dumping at sea. > > Finally, an issue which appears not to have been studied in detail is the > risk of the CROPS scheme causing large g In the deep ocean as hydrate > deposits, which are then later destabilized as the oceans warm. This could > potentially create a forcing far greater than that of the avoided CO2. > > Hopefully someone can calculate these effects, as I don't know how to. > > A > > On 10 Sep 2010 20:10, "Alvia Gaskill" <[email protected]> wrote: > > I think there is some confusion about the term "ventilation rate" as it is > used here. The work that apparently forms the basis for the 250-year > ventilation rate for the GOM discusses it in terms of how long the deep > water in the Gulf stays there before being carried back out into the > Caribbean Sea. If you look at Figure 15 from the linked reference, it shows > that the deepest water exits over the Yucatan Sill at 2040 meters. What > happens to it after that is unclear. The ventilation rate referred to here > is how long it takes the water to make it out of the Gulf, not how long it > would take CO2 from decomposing bales of crop waste to re-enter the > atmosphere. The relatively high oxygen levels at the bottom, around 5 mg/L > could accelerate oxidation of the waste, but over long periods of time it > would probably become buried in sediment and would be in an anoxic > environment, also limiting any transport of CO2 to the surface. So I would > encourage you to research this a little more before giving up on the Gulf of > Mexico. > > http://oceanografia.cicese.mx/personal/jochoa/PDFS/Rivas_etal_JPO_2005.pdf > > ----- Original Message ----- From: "Stuart Strand" < > [email protected]> > To: <[email protected]>; <[email protected]>; "geoengineering" < > [email protected]>; <[email protected]> > Cc: <[email protected]> > Sent: Friday, September 10, 2010 12:50 > Subject: RE: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz > Center, Washington DC > > > > > After our publication it was pointed out to me that the ventilation rate of > the Gulf of Mexico is... > > -- > 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]<geoengineering%[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.
