

A new method of making electricity from sunlight - spottiness
http://www.economist.com/node/18678935

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rfrey
Link to original paper:
[http://www.bc.edu/content/dam/files/schools/cas_sites/physic...](http://www.bc.edu/content/dam/files/schools/cas_sites/physics/pdf/Ren/237%20Nature%20Materials%2010%20532-538%202011.pdf)

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redthrowaway
I find it interesting that everyone ignores the obvious, and most common,
method of making electricity from sunlight: fossil fuels. It strikes me as odd
that there's such a disconnect between what we say and what we mean that the
oldest and most prevalent form of solar-generated electricity gets ignored.

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serichsen
Cute. Even the current photovoltaic cells do not make economic sense. Why
should a five times more inefficient method be better?

If anything, they should look whether there are other temperature gradients
they could use for this, but I suspect that the conversion still is not great.

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pbhjpbhj
> _liberating electrons from a semiconducting material such as silicon. Or you
> can concentrate the sun’s rays using mirrors_

// Or you can concentrate the suns rays in organic material growing bio-diesel
crops. Bit more lag but it's still essentially solar energy capture.

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rflrob
The question they don't address is what the relative cost of these
thermoelectric cells is. I'll grant that they're still in prototype phase, but
some mention of the estimates of cost would be nice. I, for one, have no idea
how much bismuth telluride costs.

~~~
dkastner
You'll also need plenty of hafnium, titanium, and molybdenum. Not exactly
abundant resources. All that just to get a 4% solar->electricity conversion
rate. You can put these panels under your solar water heater and get slightly
hotter water with an additional trickle of electricity into your home. Maybe
you could power a pair of USB heated gloves.

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scythe
Bismuth telluride is a compound of bismuth and tellurium. This would seem
pedantic were it not for the fact that tellurium is _rare as gold_.

There's another tellurium-based pipe dream in the form of cadmium telluride
solar cells, which have the lucky coincidence of being highly efficient and
very cheap to manufacture. Unfortunately... _rare as gold_.

[http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%...](http://en.wikipedia.org/wiki/Abundance_of_elements_in_Earth%27s_crust)
\-- tellurium variously at 0.005, 0.001, and 0.001 ppm, and gold at 0.0011,
0.0031, and 0.004 ppm. So "similarly rare."

Friends don't let friends try to save the world with tellurium.

~~~
Daniel_Newby
"There's another tellurium-based pipe dream in the form of cadmium telluride
solar cells, ..."

Which have the benefit of using a sub-micron-thickness layer of CdTe, so that
very large scale production is plausible if new tellurium sources can be
developed. (They probably can.)

This insane thermoelectric approach uses _bulk_ telluride. Production cannot
plausibly ever scale to make this an important source of energy.

~~~
scythe
Mhm. The math for that one is not _too_ bad, requiring a "vanishingly tiny"
amount of Te per m^2, so that our current production gives a little over a
gigawatt's worth per year. We'd need "merely" two orders of magnitude
increase.

(old explanation removed)

[http://en.wikipedia.org/wiki/Cadmium_telluride_photovoltaics...](http://en.wikipedia.org/wiki/Cadmium_telluride_photovoltaics#cite_note-34)

It's actually more up-in-the-air than I thought about twenty minutes ago --
tellurium has not been widely prospected, and the source _du jour_ is undersea
ocean ridges:

<http://walrus.wr.usgs.gov/reports/reprints/Hein_GCA_67.pdf>

(
[http://docs.google.com/viewer?a=v&q=cache:FeKPblDo6GYJ:w...](http://docs.google.com/viewer?a=v&q=cache:FeKPblDo6GYJ:walrus.wr.usgs.gov/reports/reprints/Hein_GCA_67.pdf+tellurium-
rich+ferromanganese+crusts&hl=en&gl=us&pid=bl&srcid=ADGEESj5ODfjmzgQVMi96rhRj2bXy2i0cTMtgmzZYpX7ieU1VBr8NIf3hOqr1ejrnZ4WFYcALjdJjuuMI49L0wlPyCZzUByMsgZNzRDcUBxZ1EwYYl1rJoakRZVlt8uyg44tuPmfb9IS&sig=AHIEtbTgIIegE-
ZaUzTib8mHSTf717Jzrw) )

I'm still a skeptic.

