I would argue that any sequestration technique for CO2 should allow its release back into the atmosphere when needed. Why needed? For sure when the nominal background level of CO2 in the atmosphere drops to 180 ppm as the Antarctic cools following the end of the current 20,000 year component of the Milankovitch cycle. That will take place relatively soon. When the Earth so cools we will be glad to have enough CO2 stored to put back 100 ppm and achieve acceptable climate. We should view geoengineering techniques as a thermostat that works both ways as needed. One of the elegant aspects of carbon sequestration techniques is that they do no damage. Capture and storage fits that category.
_____ From: [email protected] [mailto:[email protected]] On Behalf Of Stuart Strand Sent: Monday, January 26, 2009 3:51 PM To: [email protected]; geoengineering; greenhouse effect Cc: James Lovelock; James Hansen; [email protected] Subject: [geo] Re: Crop residue ocean permanent sequestration Alvia, Point one is semantics. Crop residue carbon sequestration is clear enough in my opinion. 2. We did not analyze the costs of cellulosic ethanol with or without CO2 capture. We did use Aden et al's analysis to calculate the carbon balance of a cellulosic ethanol plant. Most of the carbon dioxide emitted from cellulosic ethanol is not emitted at the auto tailpipe, rather it is emitted from the production facility, because fermentation is not very efficient and lignin etc is burnt to provide the energy for distillation of the ethanol. Approximately 65% of the total carbon emitted from the production and use of cellulosic ethanol is emitted from the production facility, so that fraction could be captured, albeit with greater complexity and cost. 3. You are correct, large scale crop residue sequestration in the deep ocean cannot compete in the present carbon market. But the present carbon market is flawed in many ways that make it largely ineffective for dealing with the enormity of the crisis. It is vulnerable to cheating and regulations on carbon emissions are too lax. Most importantly the present market does not place an appropriate premium on permanence. A carbon market probably could be made to work effectively, but only after major reform that would result in increased carbon prices. 4. The saturation and SG of bales of crop residue is one of the uncertainties in our analysis. The off line discussions you have publicized were very preliminary. I hope that we can do some formal experiments soon, but this work is unfunded so resources are scarce. As to your conclusion, it seems to assume that sequestration has to be done at less than 33 euro per t CO2, the 2006 maximum carbon price. I would argue that permanent removal of CO2 from the atmosphere is worth more than that, as will become apparent as the situation worsens. Our paper argues that options for permanently removing carbon from the atmosphere are limited and flawed, and that crop residue sequestration in the deep ocean is the least problematic and could be done right away. = Stuart = Stuart E. Strand 167 Wilcox Hall, Box 352700, Univ. Washington, Seattle, WA 98195 voice 206-543-5350, fax 206-685-3836 <http://faculty.washington.edu/sstrand/> http://faculty.washington.edu/sstrand/ --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
