Andrew, All of these arguments were answered last year when the paper came out, but apparently you did not digest them then, so I will repeat, briefly. Burning biomass for electricity or making ethanol avoids fossil fuel carbon emissions = 30% of the starting biomass carbon. Biomass is a poor fuel, better to bury it. Please read the paper. Or is there something about 3>1 that you don't understand?
Biomass could be co-fired with coal to generate power and if the CO2 from that process were captured the overall C sequestration and avoidance efficiency would be about 115%, but will plant operators divert generating capacity from coal to the poor fuel, biomass? Methane from biomass is unlikely to be a problem because anaerobic processes in the ocean is dominated by sulfate reduction. Thus, methane diffusing from within the stacked bales would be oxidized by sulfate reducers. Please take the time to educate yourself on these matters before you post ill-informed opinion to the group. BE = Stuart = Stuart E. Strand 490 Ben Hall IDR Bldg. Box 355014, Univ. Washington Seattle, WA 98195 voice 206-543-5350, fax 206-685-9996 skype: stuartestrand http://faculty.washington.edu/sstrand/ From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Lockley Sent: Friday, September 10, 2010 2:21 PM To: [email protected] Cc: geoengineering Subject: Re: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC 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 gas 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]<mailto:[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]<mailto:[email protected]>> To: <[email protected]<mailto:[email protected]>>; <[email protected]<mailto:[email protected]>>; "geoengineering" <[email protected]<mailto:[email protected]>>; <[email protected]<mailto:[email protected]>> Cc: <[email protected]<mailto:[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]. 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.
