Dear Dan and Andrew‹It would be interesting to see if an analysis could be done for laser destruction of methane. Its concentration is much higher (thousand times or so) than for CFCs and it must be a good deal less stable, so energy might be lower to break it apart. Then there is the question of the benefits side and doing so for climate change instead of stratospheric ozone depletion. There are already lots of pretty cost effective mitigation measures for methane‹so might be worth someone looking at disassociating it in atmosphere (its 20-year Global Warming Potential compared to CO2 is 75, so reducing its concentration would have an early effect‹just what we need).
Mike MacCracken On 12/31/08 3:36 PM, "Dan Whaley" <[email protected]> wrote: > I suppose, although the abstract mentions that a 10 to 20 fold theoretical > improvement in efficiency would be needed to even get the proposal within > rational reach of consideration. > > There should probably be a grouping in these wikis between the ideas which > have received some serious consideration over time versus the offhand > proposals which even the propsers see as farfetched. To the uninitiated, it > appears that all these concepts are approximately equivalent. > > Also-- "blowback" effects from N2O? Strange use of language. Any rational > methodology simply deducts the radiative forcing of N2O produced from the CO2 > sequestered and only claims the conservatively calculated net benefit. Most > models in the southern ocean put that at considerably less than 10%. I > wouldn't say that's one of the things that makes OIF 'controversial'... it's > a factor for sure-- but so is accounting for all CO2 produced by the > consumption of fossil fuels involved in carrying out the experiment itself. > The effects on deep ocean oxygen and acidity, or downstream nutrient depletion > would probably be better topics of debate. > > d > > On Wed, Dec 31, 2008 at 12:24 PM, Andrew Lockley <[email protected]> > wrote: >> There's a proposal on the wiki for CFC destruction using lasers. I >> thought it worthy of inclusion. There are probably other techniques >> I'm not aware of. >> >> details at >> http://en.wikipedia.org/wiki/Greenhouse_gas_remediation#CFC_Photochemistry >> >> A >> >> 2008/12/31 Dan Whaley <[email protected]>: >>> > I understand the intent to include all greenhouse gases, but the reality >>> is >>> > that while there is a history of emissions control for many gases, there >>> is >>> > really no established history for the active *removal* of all gases. The >>> > simple fact is that unless I am forgetting something I know of zero >>> > proposals to enable the direct atmospheric removal of anything other than >>> > CO2. >>> > >>> > Are there biologic processes for instance that demand atmospheric N2O or >>> > atmospheric CH4 instead of CO2? Perhaps, but none that I am aware of >>> > proposed by humans for mitigation purposes. >>> > >>> > I think Atmospheric Carbon Removal is the closest thing we here have come >>> up >>> > with that accurately identifies the category. >>> > >>> > It distinguishes it from CCS (i.e. flue-gas capture and sequestration) at >>> > focuses it specifically on OIF, Lackner trees, and some of David's >>> > concepts. Accelerated weathering perhaps. >>> > >>> > D >>> > >>> > On Wed, Dec 31, 2008 at 8:08 AM, Mike MacCracken <[email protected]> >>> > wrote: >>>> >> >>>> >> Dear Andrew--While I have not yet had time to check out your efforts and >>>> >> offer thoughts on editing, some ideas for the next effort. >>>> >> >>>> >> So that you are not just covering the removal of CO2, I would think >>>> >> something like "Atmospheric composition management" of "Active >>>> management >>>> >> of >>>> >> atmospheric composition" would be best--you might even have it be a >>>> >> subheading for "Atmospheric composition" and then have links from >>>> >> geoengineering-related entries. In addition to the removal ideas for >>>> CO2, >>>> >> you could cover any that arise for methane, and even go back to the ones >>>> >> proposed for CFCs that included lasers to decompose them, with the laser >>>> >> beam bounced back and forth between mirrors on mountaintops to get a >>>> >> sufficiently long pathlength to give high probability of striking a >>>> >> molecule. >>>> >> >>>> >> And, of course, one would want to somehow link this in to mitigation of >>>> >> GHGs--which would be said to do at the source. And you would need to >>>> link >>>> >> to >>>> >> ideas about reforestation/afforestation. >>>> >> >>>> >> Mike MacCracken >>>> >> >>>> >> >>>> >> On 12/30/08 9:35 PM, "Andrew Lockley" <[email protected]> wrote: >>>> >> >>>>> >> > >>>>> >> > I am planning to start a new wiki on the various techniques such as >>>>> >> > fake plastic trees, biochar etc, designed to remove GHGs from the >>>>> >> > atmosphere. >>>>> >> > >>>>> >> > To avoid the naming dramas, I suggest the following, but would >>>>> invite >>>>> >> > new/better suggestions: >>>>> >> > >>>>> >> > Carbon Dioxide removal? (too specific) >>>>> >> > Greenhouse gas removal? (too geeky?) >>>>> >> > Gas Geoengineering? (will anyone know what it means) >>>>> >> > >>>>> >> > A >>>>> >> > >>>>>> >> > > >>>> >> >>>> >> >>>> >> >>>> >> >>>> >> >>> > >>> > > > --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
