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

From: <Dawsonzhu@aol.com>
Date: Sat Dec 16 2006 - 21:47:01 EST

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 Sat Dec 16 21:47:55 2006

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