Alan Epstein,  an MIT professor of aeronautics and astronautics has been researching very small jet turbines that could be used to generate electricity (he says between 10 and 100 watts.)

Epstein originally created out of boredom and a wandering mind during jury duty, and is close to a very small jet engine, built with extremely small silicon wafers, about the size of a quarter, that could power a laptop for hours.  Potential applications include longer power for laptops, and a reduction in weight for army personnel who need to carry with them enough computer battery power for multiple days of operation without a recharge.

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