Robert, Setting aside SRM for the moment, have you ever revisited the wedges paper to incorporate the full suite of potential CDR strategies? This strikes me as an obvious way to broaden the wedge concept. I imagine this has already been done one way or another ....
Josh Horton [email protected] http://geoengineeringpolitics.blogspot.com/ On Jun 21, 5:14 pm, David Keith <[email protected]> wrote: > Of course it's not only an emergency strategy. > > Each group that has begun to think about it seriously has realized that. > > I said just this to the group in Lima an hour ago. > > David > > From: Alvia Gaskill [mailto:[email protected]] > Sent: Tuesday, June 21, 2011 3:07 PM > To: [email protected]; [email protected] > Cc: [email protected]; David Keith > Subject: Re: [geo] Cost of Air Capture and the APS report > > "I leave the Lima group with a final thought. Is SRM only an emergency > strategy? What are the pros and cons of a continuous ground-bass deployment > of 1 W/m^2 of stratospheric aerosol negative forcing, as an overall helper on > the margin and as a way of learning about larger deployment?" > > No, it shouldn't only be considered as an emergency option, a term which has > never been adequately defined anyway and tends to be used as a defense > against the media and the opponents of geoengineering by those working in the > field who can't or don't want to pardon the expression, "take the heat." > > Paul Crutzen included use of stratospheric aerosols at about this level of > negative forcing to replace the loss of tropospheric sulfate from pollution > controls and others have made similar proposals (including me). To get to > some kind of full-scale offset of AGW forcing (back to pre-industrial from > today or some future date) you have to pass through 1 W/m2 anyway. Plus, a > slowdown of warming now means less ice melted that we can't replace in the > future (given what we know about how difficult that will be). This applies > to cloud brightening as well or some other technology that could achieve the > same impact. But i also note that to get to 1 W/m2 you have to get through > 0.1 and 0.2 and 0.3, etc. You have to start somewhere. > > > > ----- Original Message ----- > From: Robert Socolow<mailto:[email protected]> > To: [email protected]<mailto:[email protected]> > Cc: [email protected]<mailto:[email protected]> ; > [email protected]<mailto:[email protected]> > Sent: Tuesday, June 21, 2011 2:57 > Subject: RE: [geo] Cost of Air Capture and the APS report > > Ron, Ken, and others: > > Given that the Lima meeting is in its middle day today, let me push > everything aside to write answers to Ron's questions. I am speaking only for > myself. > > 1. Yes, there is only one change, aside from formatting, in the June 1 > version of the APS report. We say so on the second page of the preface. As we > were issuing the unformatted version at the end of April, David Keith > identified a clear mistake in our report, involving the pressure drop per > meter for a specific packing material, which we had carried forward from a > 2006 paper. Fortunately, one member of our committee, Marco Mazzotti, was an > author of that paper. With one of his co-authors, he updated his earlier work > with new information from the manufacturer of the packing, additionally found > an error in his earlier analysis, followed a hunch that there was an easy fix > for us by substituting one packing for another, and we buttoned this up. The > new packing is cheaper, but we verified that our initial cost estimate for > packing had been so conservative that the new packing actually fit the > assumed price better. I am aware at this time of no outright error in our > report. People may find some, and if they do I hope they will tell me about > them. > > 2. Item a. In my view, the experts (specifically Keith, Lackner, and > Eisenberger) were given adequate time to interact with us. Our project took > two years. We established groundrules at the front end that there would be an > arms-length relationship and (confirmed more than once) that as a matter of > policy we would not learn confidential information. All three presented to us > at our kick-off meeting in March 2009, reviewed a draft (along with almost 20 > others) in April 2010, and communicated repeatedly with us. I had the > personal goal of being sure that the key ideas in their work were understood > by our committee and commented upon in our report. Nonetheless, none of the > three of them is happy with the result. One comment all three would make is > that they would have done the study differently. They would have asked what > air capture could cost if one were to assume success in the presence of risk; > our committee felt that in the absence of reviewable published data, this was > an illegitimate task. We decided to include one cost estimate based on a > benchmark design, resulting in a system whose cost is probably quite a lot > higher than $600/tCO2, and in the process, by careful attention to > methodology, the reader can learn how to think about costs. Personally, I now > appreciate (and the reader will too who works through the calculation) that > the most underestimated cost factor is the pressure drop as air moves through > the contactor, which enters not only as a an energy cost but also through its > impact on "net carbon," even for largely decarbonized power. All three > experts are working on low-pressure-drop systems for this reason. > > Item b. I know of no comparable study. We call explicitly for some group to > do some comparable analysis of biological air capture: afforestation, > biochar, BECS - maybe one study for each. In that instance it will be > critical to understand what scale-up looks like: small-scale deployment is > cheap and could have major co-benefits. But how much planetary engineering is > entailed if one aims for the reduction of atmospheric CO2 by 1 ppm per year > for a hundred years - negative carbon on a monumental scale? > > 3. ASAP means "as soon as possible." I think one needs to be careful > with such language. If one is in a car, one can slam on the brakes or brake > carefully. Both could be called smallest-possible-distance braking, but the > meaning of "possible" would be different in the two cases, with more > conditionality in the second case. When Pacala and I wrote the wedges paper > in 2004, we identified a societal goal of an emissions rate at mid-century no > higher than today's; if restated in today's language, 30 MtCO2/yr in 2061. > That goal is now considered timid by many - it is associated with "3 > degrees," while the more politically correct "2 degrees" is associated with > 15 MtCO2/yr. My view is that we shouldn't choose between these two goals now. > We should make that decision in 10 to 20 years, but concentrate now on > getting on a new path. But I think it is also important, and will make the > activist community more credible, if we concede in some prominent way that > the world could overreact to climate change, undervaluing what can go wrong > when "solutions" are deployed, from the destruction of forest ecosystems to > nuclear proliferation. In short, we want to keep conditionality at the front > of our minds, not treat it as an afterthought. > > We should be suspicious of distractions, and, to my mind, direct air capture > is one of these. Air capture is a close neighbor of post-combustion capture > at coal and gas power plants, a much cheaper mitigation strategy. This simple > fact about technological neighbors tells is to be very careful always to > state that near the top of the mitigation agenda for several decades is > decarbonizing the global power system. There is something grotesque about > pulling CO2 our of the air at one place while pouring it into the air at > four-hundred times greater concentration at another place. First things first. > > The underlying irresolvable argument is political. Is a radical goal (2 > degrees) that requires instant comprehensive mitigation best suited to spur > action, even when activists widely concede (mostly privately) that the goal > is unachievable and has the potential to lead people to throw caution to the > winds? Or is a liberal goal (3 degrees) -- more suited to deliberative > action, more respectful of the legitimate needs of developing countries, and > more matched to the building of coalitions -- a better choice? Which is more > likely to lead to our getting started and not having our grandchildren > looking at "5 degrees"? > > I leave the Lima group with a final thought. Is SRM only an emergency > strategy? What are the pros and cons of a continuous ground-bass deployment > of 1 W/m^2 of stratospheric aerosol negative forcing, as an overall helper on > the margin and as a way of learning about larger deployment? > > Rob > > From: [email protected] > [mailto:[email protected]] On Behalf Of > [email protected] > Sent: Tuesday, June 21, 2011 12:03 PM > To: Robert Socolow > Cc: [email protected]; [email protected] > Subject: Re: [geo] Cost of Air Capture and the APS report > > Robert and ccs > > 1. Thanks for the added links and information. Not yet mentioned on this > list is that your APS panel changed (added?) only one footnote (#18) - and as > near as I can tell - changed no conclusions. Still projecting $600/tonCO2, > it seems. > > 2. As you may have noticed there has been some discussion this list on > how we (Society) should be evaluating climate technologies. I do think that > groups such as the APS have done and can do a great public service with > studies of the type you have performed here (but I know too little of the > topic to know if your panel or Keith should be given the higher believability > rating). I thank you for taking on a thankless task. Two questions for > you, based on my concerns (as at what may happen in Lima, for instance) > > a. Do you feel that the air capture experts were given adequate time to > present to your panel - or might you now do something different procedurally? > > b. Are you aware of any other similar (highly technical, multiple and > presumably un-biased panelists) technology assessment in the works (by > professional societies or anyone) for any of the other field(s) of > geoengineering? > > 3 Your proposal with Prof Pacala to use the simplified concept of seven > wedges reaching 1 Gt C each in 50 years time (and 25 Gt C each avoided) has > been very helpful (unfortunately not yet very well followed). Several > > ... > > read more » -- 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.
