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
