the old hand-crank model has been superceded: www.technologyreview.com/print...e.aspx

The new generator will make the laptop much easier to power than it would be with a hand crank, in part, because the users will be able to operate the generator in a variety of ways, including holding the device (the size of two hockey pucks) in one hand and pulling the string with the other, or clamping the generator to a desk, attaching the string to one foot, and using leg power. "We wanted something that could take advantage of other muscle groups in the human body that can put out a lot more energy than the muscles that you get when you're just turning a crank," says Colin Bulthaup, a co-founder of Squid Labs.

To reach the project's goal of one minute of power generation for every ten minutes of laptop use, the generator would need to produce 20 watts (the laptop will require less than two watts in a primary application as an electronic textbook replacement). "With a hand-crank system, if you're gung-ho about it, you can get about five watts out of it. But you get tired after about a minute or so," says Geo Homsy, a partner and designer at Squid Labs. With the new system, generating 20 watts is comfortable, and it's possible to generate 10 watts for "as long as you want," the developers say.

The new generator is also quiet -- one of the key design requirements. "If you imagine an entire school room full of kids using this thing, it needs to be as quiet as possible. Otherwise it will drive everyone insane," Homsy says. Typical generators work best at high revolutions per minute, requiring noisy gears to step up the speed. The developers have done away with gears by custom-designing a generator that runs most efficiently at lower RPMs, a move that also makes possible a smaller device.

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what about a sewing-machine-type table-n-treadle? THAT would be something....

of course, it's not portable.