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Some scientists at Georgia Tech (and Xiamen University, China) have accidentally stumbled on an amazingly efficient and simple way to generate electricity. Its literally as simple as rubbing two pieces of plastic against each other.

Despite improvements by Wang’s team and others, such piezoelectric devices have generated mere micro-watts of power. Until, that is, they wrapped one in plastic.

While investigating one piezo generator, Feng-Ru Fan, one of Wang’s graduate students, put a layer of plastic known as PMMA on top of it for protection. The generator in turn was sitting on a different plastic called Kapton. When Fan measured the device’s performance, he consistently found it was generating a higher voltage than expected. Fan and Wang spent months investigating what was happening, before concluding that the added power was coming from static electricity. When the PMMA and Kapton come into contact and rub against one another, friction generates electrical charges.

Science Magazine, Jan. 4, 2013

Sounds like something out of Thomas Edison's lab, doesn't it? "Science is 1% inspiration and 99% perspiration." This is a great example of why you cannot predict innovation, you can only fund people with good track records and stay out of their way. A few more details below the fold.

Their NanoLetters paper is available on-line for free; and the innovation is so simple, anyone with a high school education can understand it. The hard part is creating the nano-material in the first place. (Its the microscopic bumping of the surface which raises the surface area, and hence the current production.)

Such a flexible polymer TEG gives an output voltage of up to 3.3 V at a power density of ~10.4 milli-watts/cm3.

NanoLetters paper

10 milliwatts doesn't sound like much (1/100th of a Watt); but you get that from one square centimeter of one layer of this device.

There are 6.25 sq cm in one sq. in. So that is ~62mW/sq in (about 1/16 W). The bottom of one of my shoes is about 12" x 3", or 36 sq in. Walking at a normal pace should generate about 2 Watts. And that's with one layer of material.

Wang says he is already considering making square meter–sized devices with up to 200 layers of nanogenerators stacked atop one another for use in harvesting ocean power. Such a device may be able to produce as much as 40 kilowatts of power per cubic meter, which could make nanogenerators a large-scale power source.

Science Magazine, Jan. 4, 2013

Forty KILO-watts from a bunch of inert plastic floating in the ocean. BTW, the plastic ought to cost out at under $1/Watt at current prices for Kapton (which is sort of expensive).


And this administration is still pushing for clean coal, nuclear subsidies, and fracking. Meanwhile, the GOP are still screaming "Drill, Baby, Drill." Washington makes me sick. Science makes me feel good.

Too bad our owned-by-oil-company politicians will underfund this, and the Chinese will take it over.

What, me cynical and pessimistic?

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