A new method of making electricity from sunlight | Hacker News Reader

A new method of making electricity from sunlight

economist.com

66 pointsspottiness11 comments

Link to original paper: http://www.bc.edu/content/dam/files/schools/cas_sites/physic...

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.

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.

>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.

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.

http://www.jitlab.com/BISMUTH-TELLURIDE-99-999-10G-p/l-28271...

10 dollars for a gram it seems.

I guess for some kind of comparison:

Copper is $0.008 per gram.

Potassium (pure) is $1.50 per gram

Magnesium is a few cents per gram

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.

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%... -- 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.

"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.

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...

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... )

I'm still a skeptic.

That's very interesting, but I can't say I've heard of Glenn Beck touting Tellurium Exchange. Nor has anyone told my why now may be the best time ever to own tellurium, although your post is giving me a pretty good idea.

I suspect rarity has less to do with the issues surrounding gold than its ancient desirability, its role throughout history, and the cultural baggage it's picked up in consequence. You probably carry as much rare as gold material in your mobile phone as you'll find in one of those solar cells, and if not, the platinum in your car's catalytic converter may more than make up the difference.

Don't let one minor inconvenience get in your way. ;)

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