You mean NF3, of course, not NH3 (ammonia).
I guess we'll have to be careful how we spread biochar. When I tried to
reduce particle size by running charcoal from my woodstove through my
chipper, the cloud of black dust brought the fire department running
because it was a convincing imitation of a serious structure fire. The fine
dust does go airborne readily, and I notice that getting it into the ground
is an issue in some of the articles I have read. An efficient granulation
technology would help.
Joel
At 02:38 PM 8/8/09 -0400, you wrote:
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
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