Greg, Ken, and list I concur mostly with what Ken and Greg have below, but write to keep this nomenclature topic alive. This especially responds to Dr. Caldeira (below) who said: " We need a clear term that refers to these centralized industrial direct air capture approaches and distinguishes them from distributed biological or geochemical approaches.
I have spent more than an hour trying out subscripts, superscripts, hyphenation, and more to differentiate our discussion topics. I have concluded we "need" to stick with the term CDR (assumed, but not used much in this thread). Ken's sentence above/below gives us possible terms such as Bio-CDR and Geo-CDR (or Geochem-CDR?). How about DAC-CDR for the last (final?) possibility? Then any other use of DAC fits into something other than CDR (such as DAC-Fuels (carbon neutral), DAC-EOR (carbon positive), etc. - but this list doesn't care what names are associated with these approaches. More inserts below Fr om: "RAU greg" <gh...@sbcglobal.net> To: kcalde...@gmail.com, "John Gorman" <gorm...@waitrose.com> Cc: rongretlar...@comcast.net, "Geoengineering" <Geoengineering@googlegroups.com>, "Oliver Morton" <omeconom...@gmail.com> Sent: Tuesday, March 27, 2012 3:51:11 PM Subject: Re: [geo] Calgary meeting on Direct Air Capture - thoughts? Ken et al., As Ken, I also don't have an objection to Direct Air Capture, and to equating this with centralized industrialized processes. If I have a vat of algae consuming CO2 to form biomass or a tub of calcium hydroxide spontaneously sucking CO2 out of the air to form (bi)carbonates, I have a centralized Direct Air Capture system. However, the thermodynamics and economics of the preceding are very different from those of centralized industrial systems that remove CO2 from air to make concentrated CO2. Nevertheless, the results of high profile studies on the latter have been used to characterize and pass judgement on systems like the former, apparently also including the prospects for any form of active CO2 removal from air, be it centralized or decentralized (see the quotes in my earlier email). [RWL1: You haven't and maybe wouldn't include Biochar as a third DAC example - but maybe some would. I sense you are later equating DAC = Direct AIr Capture to just plain "Air Capture", of which I suppose Biochar might/could more logically be a part. I would not classify Biochar as "centralized Industrial" - but it obviously could be. What distinction would you recommend here in this "centralized industrial" characterization - especially for Biochar? I am proposing that this is NOT a useful discriminator. Aside: I think I understand what you mean by "quotes in....earlier email" - but I didn't take any (of three?) as applying to Biochar. But my main point is that I think we should let DAC only mean the three things meant at the Calgary meeting: carbon negative, carbon neutral, and carbon positive. Both the DAC and CDR worlds would seem to have enough of an inclusion problem and no need to add to it by stretching DAC (or AC) to include words like algae, calcium hydroxide and/or Biochar. ] I say it's way too early to write off pro-active air capture for the next 50 years, unless such inaction is supported by studies (of the type Socolow et al. and House et al conducted) that are extended to the other approaches. Let's not make sweeping and negative judgements about air capture until we know what all of the options are and until their capacity, safety, cost, and net environmental benefit have been objectively studied and compared to other strategies. Any discussion of air capture needs to start with acknowledging that over half of anthro CO2 is being mitigated by such processes right now. [RWL2: Not sure I can agree with this last. We sometimes see about 25% of the added annual CO2 each going into new added biomass (NPP) and into oceans - but neither seems quite right to call "mitigation", "capture" nor especially "sequestration". I think you are here using DAC in too broad a meaning. But I of course strongly agree that nothing stated about any DAC option should be transferred to any other CDR approach. ] As for Ken's fear of successful air capture dissuading emissions reduction and therefore increasing climate risk this century: relative to emissions, natural air capture is reducing climate risk right now. How about trying to safely build on this achievement, just in case sufficient emissions reduction continues to elude us? [RWL3: I somewhat like the use of "natural air capture", and believe Biochar fits into that phrase. But I think there are better ways to distinguish between technologies. Can you spell out what other technologies you are thinking of here? No till? I am thinking of needing to consider additionality. I believe/hope we can all agree that all CDR (air capture or not) needs further analysis and R&D.] Sorry to keep perseverating on this, but I wouldn't do it if I didn't think it was critically important that we not prematurely downplay/write off all air CO2 capture based on very narrowly focussed studies fixated on the idea that conc CO2 be the end product. Let's find out what our true options are and their cost effectiveness - broader thinking and more research needed. [RWL4: Mostly in agreement. But I think the DAC researchers only propose CDR through CO2 pumped deep underground. Is there any other DAC approach to CDR? I am trying to keep the minimum number of technologies in this category "DAC". I presume that the descriptive term "artificial trees" is out. To be as complete as possible, BECCS needs to be included on the concentrated CO2 side, but not (?) on the NAC side. BECCS attributes are very different from biochar, no-till, afforestation, etc. - but still makes sense in a category called Bio-CDR, but not Bio-DAC Bit more at end of Ken's message below. Ron Regards, Greg From: Ken Caldeira <kcalde...@carnegie.stanford.edu> To: John Gorman <gorm...@waitrose.com> Cc: rongretlar...@comcast.net; Geoengineering <Geoengineering@googlegroups.com>; Oliver Morton <omeconom...@gmail.com> Sent: Mon, March 26, 2012 1:04:29 AM Subject: Re: [geo] Calgary meeting on Direct Air Capture - thoughts? I do not have a strong objection to Direct Air Capture, by which I am referring to direct air capture at centralized facilities using industrial processes. I am not commenting on distributed methods of direct air capture using biological means or chemical weathering. I have an objection to presenting industrialized direct air capture as something that has good potential for substantially reducing climate risk this century. Were I running a federal research program, I would support research into industrialized direct air capture. I was responding to Greg Rau's question about business model. Insofar as these companies are real businesses, they must be in the business of selling CO2, not reducing climate risk. There is a danger in presenting industrialized Direct Air Capture as something that can substantially and affordably reduce climate risk this century. It can give people the impression that it is OK to emit CO2 now because if things do get really bad, we will be able to suck it back out of the atmosphere later. It should not be represented as a serious candidate for near-term climate risk reduction. Doing so could increase climate risk this century. On the other hand, industrialized Direct Air Capture might play a role in climate risk reduction in the end game. For example, maybe climate change is a real disaster, we have already deployed SRM and nearly all anthropogenic sources of CO2 have been eliminated. In this case, industrialized air capture of CO2 might be a way to get out of continued SRM deployment. [RWL1: Agreed with all of above. The emphasis needs to be on deep uncertainty about its future availability for CDR. ----- Incidentally, I notice that the term "Direct Air Capture" generates a lot of confusion, since plants and distributed chemical weathering processes also capture CO2 directly from the air, yet people often use 'DAC' to refer only to centralized industrial direct air capture of CO2. We need a clear term that refers to these centralized industrial direct air capture approaches and distinguishes them from distributed biological or geochemical approaches. [RWL2: This last sentence is what led to this response. My suggestions are two-fold: 1) put added modifiers on the term DAC, and 2) put added (your) modifiers on the term CDR. Ron] On Mon, Mar 26, 2012 at 8:44 AM, John Gorman < gorm...@waitrose.com > wrote: " the strong rejection of DAC by Dr. Caldeira", Is this available somewhere? did I miss it? thanks john gorman <blockquote> ----- Original Message ----- From: rongretlar...@comcast.net To: Robert H. Socolow ; Geoengineering Cc: gh...@sbcglobal.net ; Ken Caldeira ; Oliver Morton Sent: Sunday, March 25, 2012 8:02 PM Subject: Re: [geo] Calgary meeting on Direct Air Capture - thoughts? Prof. Socolow, list, etal 1. Thanks for your DAC response (in full below). I have now spent a good bit of time on the excellent Ppt you prepared for the Calgary meeting, and I have also re-read the full APS report. If anyone has a way of getting more of such Calgary-presented PPt material made available, that would be very helpful. Anyone know of any plans to make more of the Calgary dialog available? 2. We have now had plenty of time for some defense from DAC supporters. It is unfortunate that there has been none. It would seem you have won the battle - but I still hope to hear more from the four DAC corporations or anyone else at the Calgary meeting. I support the strong rejection of DAC by Dr. Caldeira, </blockquote> -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. 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 geoengineering@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. 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