By Hank Green

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.
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