Rich... Definition of GWP (Global Warming Potential http://unfccc.int/ghg_data/items/3825.php) is the comparison on a per molecule basis of how much radiative forcing a given gas has compared to CO2 which is fixed as 1 (it's not a perfect index... but tries to makes things, as best as possible, apple to apple comparisons. Thus it's actually the number of molecules in the atmosphere that matter ppm/b/t not the volume ppm/b/tv per se.
1 NF3 molecule = 17,000 CO2 molecules in terms of warming. So saying that it's a matter of volume and that the volume is small and therefore it is a signficant problem really just doesn't hold water. Further the growth in emissions of NF3 has been geometric, suggesting that we should be taking a close look at it now instead of later when it becomes more of a problem. The main thrust of the paper your provide suggests that: "With 2008 production equivalent to 67 millionmetric tons of CO2, NF3 has a potential greenhouse impact larger than that of the industrialized nations’ emissions of PFCs or SF6, or even that of the world’s largest coal-fired power plants." Perhaps this is small beans compared to the whole, but not insignificant and I'm just suggesting that it shouldn't be ignored. This seems like a fairly important drawback of PV, unless, of course, we're able to manufacture PV without NF3s as the article you linked to suggests is quite possible. Lastly, I think a very important warming agent that hasn't got a lot of attention is "Black Carbon"... could be 2nd or 3rd most powerful warming agent that humanity is releasing and could be contributing to 40-50% of warming in arctic.... http://www.nasa.gov/topics/earth/features/warming_aerosols.html http://www.igsd.org/blackcarbon/documents/IGSDBCClimateBriefingNoteJune2009.pdf The good things is that Black Carbon has a very short lifetime in the atmosphere and therefore can be a good target for quick climate mitigation... great news for those who would work to mitigate climate change... Best, Ryan On Fri, Aug 7, 2009 at 9:33 PM, Rich Bernstein <[email protected]> wrote: > On Wed, Aug 5, 2009 at 6:08 PM, Ryan Hottle<[email protected]> wrote: > > Thanks Rich, > > This is helpful... Yet, you're right, where's the data? > > > > NASA I tend to trust... company publications not so much. Any gas which > has > > risen from 0.02 ppt to 0.454 ppt in the past thirty some years and has a > GWP > > (Global Warming Potential) of 17,000 times that of CO2 (CO2 GWP = 1) is > > certainly of some concern. I.e. can't simply be written off as a "big > coal" > > conspiracy. We shouldn't let our desire for certain technologies allow > to > > manipulate > > It's the combination of GWP and volume that matters. And total volume > is very small. It's just four times bigger than they previously > thought. Before they thought it was small enough to be basically > irrelevant (compared to CO2), now it might be enough to matter (even > though we're still talking 0.15%). > > > Rich could certainly be right that in comparison to coal generation solar > > still wins out. What percentage of total NF3 is produced by solar? > > Don't know but it's probably in line with how much of silicon etching > is done for PV vs. computer chips, TVs, etc. > > > What > > would happen if existing technologies are scaled up to replace coal > > generation without consideration of NF3? > > >From the one example I found that gives any indication of the amount > of NF3 produced by PV manufacturing, it would take an additional 1 > year of not burning coal to compensate for the NF3 produced, in > addition to the 1 year or so due to the energy consumed in > manufacture. > > > What is the residence time of NF3 > > in the atmosphere? > > Current estimate is 550 years. This is from what appears to be the > other main source of all the articles on the issue: > > http://web.viu.ca/earle/geol-412/2008GL034542.pdf > > [...] > > > I sense a very defense stance on solar....Why is everyone so attached to > PV > > anyway? Solar hot water makes much better economic sense. Concentrated > > solar look good in desert climate... we might get some of that if HVDC > smart > > grid technologies ever come. Microhydro is wonderful (single moving > part, > > lasts longer than PV, can be manufactured regionally [i.e. in Ithaca], > and > > has minimal impact on stream ecology) particularly if you have the > > topography which Ithaca has. Energy conservation and efficiency is first > of > > course. And, of course, I think biomass makes a lot of > sense--particularly > > on-farm applications, Karl--where it can be deployed for both heat and > > power, sequester C, and create a powerful soil amendment. > > I'm not in any way defensive. PV has quite a few strengths and also > some weaknesses. This just isn't really one of them. The problem > with solar hot water is that it doesn't generate electricity. > > > Ok. All the best. Good discussion. Thanks for references Rich, you've > > obviously been paying attention to this issue... you own a PV > installation > > company? ;) > > > > Ryan > > No, I don't own a PV-anything company, and I'd never heard of NF3 > before. I just spent 20 minutes checking sources. > > -- > Rich > _______________________________________________ > For more information about sustainability in the Tompkins County area, > please visit: http://www.sustainabletompkins.org/ > > RSS, archives, subscription & listserv information for: > [email protected] > http://lists.mutualaid.org/mailman/listinfo/sustainabletompkins > Questions about the list? ask > [email protected] > free hosting by http://www.mutualaid.org > _______________________________________________ For more information about sustainability in the Tompkins County area, please visit: http://www.sustainabletompkins.org/ RSS, archives, subscription & listserv information for: [email protected] http://lists.mutualaid.org/mailman/listinfo/sustainabletompkins Questions about the list? ask [email protected] free hosting by http://www.mutualaid.org
