JAN 08

Generally, solar power aims at efficiencies of roughly 30%. If they can get to 30, they're happy. Photovoltaics often hang out around 15% for folks whose pockets aren't too deep.

So when the guy who invented to Super Soaker water gun said he was looking at a 60% efficient solar engine, I decided that he was a crazy person.

But I read the article anyway and, lo and behold, I think he may have something. His project is featured in this month's Popular Mechanics and it has received funding from the NSF, not known for giving money to just anyone. Turns out the Super Soaker's inventor, Lonnie Johnson, is also a nuclear engineer with over 100 patents.

The solar engine he's working on is similar to a conventional heat pump, which uses temperature gradients to create mechanical or electrical energy. But, as of yet, these engines haven't managed to compete with solar-powered boilers.

The "Johnson Thermoelectric Energy Conversion System" (I guess the name "Johnson Squirter" didn't stick for the water pistol) or JTEC has no moving parts, and so can't break down. It's basically a sterling engine, but instead of compressing a gas to move a piston, it compresses atoms to move electrons.

You can read more of the technical details at the PopMech article, but a quick run down of the possibilities should suffice for most curious folks.

Concentrate solar energy on one side of this material, and 60% of the photons that hit it come out as electrons. That's twice the highest efficiency of any solar technology, and means that the price could likely be cut in half. And solar tech is just the beginning. JTEC could harvest energy from waste heat (computer chips to power plant boilers) and even from the temperature differential between our skin and the air.

Comments (6)

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written by andy, January 08, 2008

Does anybody know about this site ( http://www.earthlab.com ) ? I have seen other environmental sites with carbon calculators like yahoo and tree huggers, but I am wondering what the deal with earthlab.com is? I saw they also published a list last month of the top ten greenest cities ( http://www.efficientenergy.org...ted-States ). Does anyone know if this site is better than the others? Fill me in!

I took their carbon foot print test and it was pretty interesting, they said that I put out 4.5 tons of carbon, does anyone know about any other tests?

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Spectrolab's cells are 40% efficient
written by Dannah Blumenau, January 09, 2008

Spectrolab's cells are 40% efficient (verified by the U.S. Department of Energy's National Renewable Energy Laboratory (NREL). These solar cells are readily available in the marketplace now.

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written by greengo, January 09, 2008

Do you think we will ever get a solar panel good enough that folks don't want to wait on the sidelines for - hoping that soon, sometime soon, we'll buy solar panels that won't be outdated a year after refinancing the house to pay for them...?

What a conundrum we find ourselves in.

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written by David, January 09, 2008

Well, in the first place, 60% is the upper, hoped-for, some-time-in-the-future figure. In second, it is not that 60% of the photons striking the device will be converted to electrons, it is that 60% of the potential heat energy should be converted to electrical energy.

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written by Kevin, January 09, 2008

60% efficiency can't even be hoped for; the article says the 60% efficiency is the carnot efficiency at that temperature differential. Anyone who's taken even an intro to thermodynamics class knows that carnot efficiency is impossible to achieve.

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Hear hear, Kevin!
written by Joel, January 09, 2008

Kevin's right. The author here should read the article again: the 60% efficiency claims in the first part of it are followed up with evidence that 60% is physically impossible, given in the second part.

Oops.

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