Re: [asa] UN Downgrades Man's Impact On The Climate

From: Jim Armstrong <jarmstro@qwest.net>
Date: Sun Dec 17 2006 - 00:28:10 EST

But As and Ga are used extensively in the ubiquitous LEDs. Indium is a
component of the clear conductive surfaces in every LCD produced, even
more ubiquitous.
So the barriers to both availability and use are nonexistent for
products in volume production today. Of course, as some say, performance
today is not a predictor of future performance. :-)
JimA

Dawsonzhu@aol.com wrote:

> Randy Isaac posted:
>
>> The trick is that it is a triple-junction
>> cell,GaInP(1.8ev)/GaInAs(1.4ev)/Ge(0,7ev) under 10 sun concentration.
>> It is very efficient but expensive. Best use is for space
>> applications where volume is a premium and a $50-$100/watt is an
>> acceptable price. Eventually it may compete with the less efficient
>> cells
>
>
>
> Hmm, not only expensive. Aside from As and P, most of these elements
> require some real effort to extract and do not have a large number of
> sources. As (Arsenic) also offers some challenging health hazards.
>
> GA is imported to the US, China seems to be the largest source of
> it. It is rather rare, and usually extracted as a byproduct of
> bauxite.
> http://minerals.usgs.gov/minerals/pubs/commodity/gallium/gallimcs06.pdf
>
> Indium is also rare; about three times as abundant as silver
> or mercury. It's main source is from the zinc ore sphalerite.
> http://minerals.usgs.gov/minerals/pubs/commodity/indium/indiumcs06.pdf
>
>
> Applied to technologies like LEDs, they are expected to have a long life
> time (purportedly 60 yrs). I don't know the expected lifetime as a
> photocell,
> but I'm sure it is less than that. Technologies to recycle the
> materials would
> also develop if they are used extensively. We need to remember that
> there is
> also the energy needed to extract these materials.
>
> So, applied on a massive global scale, it is not so clear if this is
> the way to go even given better figures. So, certainly not to discourage
> the passion for trying, as of yet, neither is it strongly
> encouraging. But
> at least one thing I see is that efforts to improve conversion efficiency
> have progressed.
>
>

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Received on Sun Dec 17 00:28:56 2006

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