

Breakthrough: IBM Makes a Solar Cell Out of "Earth Abundant" Materials - MikeCapone
http://www.treehugger.com/files/2010/02/ibm-new-solar-power-cells-earth-abundant.php

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go37pi
This solar cell has a "conversion efficiency of 9.6 percent, which is 40
percent higher than previous attempts to create a solar cell made of similar
materials."

Current solar cells have approximately 20 percent efficiency. Unless this
solar cell is extremely cheap, I think this is a long way from practicality.

[http://upload.wikimedia.org/wikipedia/commons/a/a4/PVeff%28r...](http://upload.wikimedia.org/wikipedia/commons/a/a4/PVeff%28rev110707%29d.png)
\- graph of best research cell efficiencies

EDIT: "The researchers estimate that if the technology can be taken beyond its
basic state right now and achieve 12 percent efficiency, it could be an
economically viable alternative to current products." - from CNET news
<http://news.cnet.com/8301-11128_3-10451641-54.html>

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machrider
Is efficiency really the #1 criterion for practicality? I thought cost (per
watt) was.

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anamax
#1 enough.

My roof has finite surface area. If the efficiency is too low, even zero cost
isn't competitive.

That's true even of commercial facilities. Various enviro groups are already
trying to kill solar farms.

Somewhere in here, wire and other infrastructure (such as the frame) costs
matter too.

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MikeCapone
"Even with selenium this type of cell has materials cost advantages over
existing commercial thin films from First Solar made of cadmium and telluride.
Also, this cell has advantages over the CIGS (copper indium gallium selenide)
cells of the newer thin film manufacturers since indium and gallium cost more
and CIGS also uses selenium." (source:
<http://www.futurepundit.com/archives/006938.html>)

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dkimball
This is extremely heartening. I think we always over-estimate the level of
threat that we face at a given time, and underestimate the possibility of
finding some sort of a solution.

But on the other hand, not needing enormous quantities of rare earths means
that human expansion into space no longer gets a kickstart from attempts to
mine the asteroid belt... :)

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CoryMathews
IBM also said "But this is just a start. More improvements to power conversion
should be possible." So now that the poc is done they can refine it and make
it better.

Also I agree with @machrider its all about the cost per watt. Thats what is
going to make it popular or not.

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InclinedPlane
Approximately 1/4 of the Earth's crust is made out of Silicon. Tin and Zinc
may be more abundant than Gallium, but this is a ridiculous phrasing given
that Silicon based PV cells already exist.

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anonjon
This makes me wonder what the conversion efficiency and price per watt for a
tree is.

Trees (plants in general) already do photosynthesis really well, so why can't
we genetically engineer a tree that produces electricity?

~~~
graphene
_Trees (plants in general) already do photosynthesis really well_

As I understand it, that's not exactly true; photosynthetic compounds are very
efficient at harvesting light, but the chemical conversion to energy-carrying
compunds is rather inefficient, I believe on the order of 1%. That said, those
compounds are probably more valuable per joule than electricity since there is
no storage problem, so it's hard to compare the two.

The reason we can't simply genetically engineer an organism that converts
sunlight into electricity (or fuels) is that at the moment, neither the photon
harvesting process nor the chemical conversion process are well enough
understood to try to replicate.

~~~
MikeCapone
<http://en.wikipedia.org/wiki/Photosynthetic_efficiency>

