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, but we should hear from proponents 3. In the middle of your PPt, there is brief mention (and rejection) of two biological alternatives - a) afforestation/reforestation and b) BECS/BECCS - because of insufficient land. In your main APS report, this was covered in more detail, where there was also identification of c) Biochar. I assume that you would also reject that (my) option, for the same (land availability) reason - but guess it was Biochar-beneficial that you did not (?) mention Biochar in Calgary This is to try to convince you (and this list) that all three biomass options have an unrecognized (and sufficient - faster than your 100-year scenario) CDR potential. This will be as brief as I can make it - but glad to add more, should I have not been convincing below. I accept as reasonable your proposed removal of 100 ppm CO2 - and agree with your equating this to 1500 Gt CO2 = 400 Gt C 4. As Step 1, I assume that the assumed 400 Gt C can/should be separated into two equal parts for a) (additional 200 Gt C of standing biomass) and b/c) (the BECS and/or Biochar options). I will not go into detail on the a)-forestation 200 Gt C option. This is a 10% increase on the present (approximate) biomass (including below ground) amount of carbon - of about 2000 Gt C. One reference could be (list respondent) Oliver Morton's excellent book on Photosynthesis (p 300 top; more coming on this book). I don't believe this 2000 Gt C value is controversial and a 10% increase over 50 years is only about 0.2% added per year (but hopefully to be finished well earlier, with an incentive of about $1/tree??)) If we assume this takes place on 2 Gha, this assumes an eventual 100 t C/ha - which is below present standing biomass levels for many parts of the world - and likely to be obtainable in 50 years. This is roughly the approach proposed by Dr. Jim Hansen, as he strives for 350 ppm. Present pasture land is about twice this much area. 5. My second step is to choose an alternative 20 year intermediate to your 100 year and 10 year "wedges". Rather than set the upper limit to achieve the needed 200 Gt C (which would give a needed 10 Gt C/yr), I suggest that an appropriate annual b/c) limiting amount is about half that - or 5 Gt C/yr. One justification for this 5 Gt C/yr value is found on p 157 of a recent study released by WWF and Ecofys, with the pertinent part found at http://www.ecofys.com/files/files/wwf_ecofys_2011_theenergyreport_part2.pdf On p 157, the WWF-Ecofys authors show that (after allocating more than 40% of year 2050 total energy to the biomass sector), that there is approximately an equal technically available additional 150 Exajoules of Biomass still available. Dividing by 30 GJ/tonne C, this gives 5 Gt C/yr - as identified above. This value is approximately half as much as identified by Profs. Johannes Lehmann and Tim Lenton. Admittedly this is very large, but less daunting than anything in your scenarios. 6. Thirdly, replacing your single wedge by a 20-year wedge and then a 30-year rectangle (with a total period of 50 years - in part to equate to your own energy-neutral wedge periods), I propose (0.5*20 yrs + 1*30 yrs)*5 Gt C/yr = (50+150) Gt C = 200 Gt C (as desired/assumed). The still unjustified value in this computation is the 20 year initial-introduction period. This is not critical to the argument, but I think 20 years is reasonable if we treat the introduction as urgent. I am thinking of numerous relatively small (20 MW-like?; 15-20 km collection radius) pyrolysis units also supplying either electricity and/or process heat. The Ecofys system primarily uses biomass for transport sector fuels - so there can be a part of the Biochar (not through BECS) achieved by modifying some of those schemes. This use of new already identified land does not alter the WWF/Ecofys scenario. I believe that the same individuals (several billion) who will be planting the 200 Gt C in new forests are also available (and already skilled and needing employment) for the harvesting for Biochar (and BECS). Biochar can have an added BECS, but the reverse is not possible. I favor Biochar over BECS also because of the extensive out-year values from placing the carbon near the surface rather than deep underground. In addition to the obvious CO2 removal and energy values, these values include reduced water needs, conserved nutrients, reduced N20 and methane release, more food, jobs, and rural economic development, and of course added soil productivity in general (2 -3 times as much from 500-year-old "terra preta" soils in the Amazon). I have not seen an LCA that shows that the out-year benefits can/will exceed the value of doubling the energy and CO2 sequestration values in the first year via BECS (but with no-out-year benefits) - but I think Biochar will win out in most locations because of the difficulties that CCS is (already) facing. 7. To summarize - I hope/believe I have presented a reasonable scenario for BECs and/or Biochar that meets your (Prof Socolow's) scenario- and would welcome comments on all of the above-stated assumptions. As one point of reference, note that Prof. Socolow's 100 year DAC scenario has achieved only 25% (or 100 Gt C sequestered out of the needed 400) in the first 50 years. The above Biochar scenario has achieved twice as much (the full 200 Gt C) in a 50 year period (say by 2065). I am preparing (today?) several other responses pertinent to other recent DAC inputs by Greg Rau, Oliver Morton, etc., that will get into the economics - which I believe are as good as CCS, and are affordable - and way less than DAC economics. Prof. Socolow - thanks again for your response (next) that allowed this extension of your DAC analysis Ron ----- Original Message ----- From: "Robert H. Socolow" <[email protected]> To: [email protected], [email protected], "Geoengineering" <[email protected]> Sent: Friday, March 23, 2012 8:50:16 AM Subject: RE: [geo] Calgary meeting on Direct Air Capture - thoughts? >From a Calgarian mortal to the geoengineering group: My keynote at the Calgary >meeting can be found on my website, or simply by clicking on: http://www.princeton.edu/mae/people/faculty/socolow/12-03-07-Calgary-Summit-keynote.pdf Rob From: [email protected] [mailto:[email protected]] On Behalf Of RAU greg Sent: Thursday, March 22, 2012 10:35 PM To: [email protected]; Geoengineering Subject: Re: [geo] Calgary meeting on Direct Air Capture - thoughts? Ron, Thanks for asking: 1) Wasn't invited to Calgary. 2) As Socolow et al and more recently House et al. PNAS 108:20428–20433 have shown, if your game is removing CO2 from air, concentrating molecular CO2 from air is probably the last thing you want to do because of the prohibitive thermodynamics and hence cost. But what really irks me about the DAC crowd is they act as though they are inventing air capture, e.g., the Economist article's subtitle that gushes: "The idea of pulling carbon dioxide out of the atmosphere is a beguiling one. Could it ever become real?" or Marc Gunther's quote: "Most scientists believe removing CO2 from the air is expensive and impractical to do on a global scale." Let me be the first to break the good news; air capture is occurring all around us, to the tune of about 17 Gt CO2/yr. That's right, the equivalent of about 57% of anthro CO2 emissions is thankfully already being removed from air by natural process for free. I'd say that is a pretty good example of effective, low cost, global scale air capture, in contrast to the latest $1000/tonne CO2 figure of House et al. So, if one is interested in increasing air capture, the obvious places to start are figuring out how to 1) increase global photosynthesis (afforestation, ocean fetilization), 2) decrease respiration of biomass (biochar), or my favorite, 3) increasing mineral weathering rates. Then there are hybrids of 1 -3. Why start with a highly artificial and expensive process of concentrating molecular CO2 when nature provides much lower cost and less risky examples that are already in global scale operation? 3) Haven't read Marc's ebook, but assume it's along the lines of the Economist article. Perhaps he'll send me a free, autographed copy 4) See above. I've submitted a followup letter to PNAS, for what that's worth. 5) Good point - why insist on concentrated, molecular CO2 as your end product? Nature doesn't. One has to conclude that EOR is their end game, in which case this generates a net air CO2 source rather than a sink: In standard CO2-EOR, 3 tonnes of CO2 are generated from product per tonne of CO2 injected. You can be sure that oil companies will want to increase (worsen) this 3/1 ratio if they are paying >$100/tonne CO2 injected. Traditional geologic sources of CO2 for EOR are less than 1/10th this cost. So what is the DAC business model, why is venture capital interested, and what does it have to do with stabilizing air CO2? Any Calgarians care to fill us mortals in? Your humble messenger, Greg From: " [email protected] " < [email protected] > To: Geoengineering < [email protected] > Sent: Thu, March 22, 2012 3:41:23 PM Subject: [geo] Calgary meeting on Direct Air Capture - thoughts? List: 1. I thought this list had a very useful dialog a few months ago on the CDR technology called Direct Air Capture (DAC - sometimes "Artificial Trees"). I have just become aware of an invitation-only meeting on this topic - hosted by the group "ISEEE" at the University of Calgary on March 6 and 7. A preliminary agenda is available at: http://www.iseee.ca/dacs/ 2. Two useful recent descriptions of the dialog are given at: http://www.economist.com/node/21550241 and http://www.marcgunther.com/2012/03/11/direct-air-capture-of-co2-is-becoming-a-business-for-better-or-worse/ 3. Marc Gunther also had an article on the major DAC companies just as the meeting was starting at: http://chimalaya.org/2012/03/06/rethinking-carbon-dioxide-from-a-pollutant-to-an-asset/ 4. I gather from this material that Prof. Socolow was under considerable pressure to lower his (and APS') decidedly negative projection on costs. I wonder if any list member in attendance can comment on this controversy - that was covered nicely on this list. 5. I also gather there was considerable unhappiness in the present emphasis of all (?) of these DAC companies away from CDR - and instead on to uses of the captured CO2 for enhanced oil/gas production and for combination with H2 for appreciably lower carbon footprint fuel production. Any comments on these aspects - or any other part of the meeting? Thanks in advance for any additional information. Ron -- 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] . 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