Pocket Full of Power; Did you think those wireless gadgets were going to run on AAAs? Try tiny jet engines and nuclear reactors.(Cover Story)

Byline: David H. Freedman

Alan Epstein proudly points to a new jet engine his group at MIT has developed--a device designed to exceed the thrust per weight of a Boeing 737 engine. Have a look, he says, and then tosses the device across the table. It's thumbnail size, made on a silicon wafer.

Who's going to need a jet engine in his pocket? You will, so all the wireless gadgets you're likely to carry around in the future can keep going strong. Portability is a virtue but also a curse: even a Wi-Fi-capable laptop needs to be plugged in frequently to recharge. "People want longer run times, and the only way to do that right now is with bigger batteries," says James Balcom, CEO of fuel-cell firm Polyfuel in Mountain View, California. Researchers are developing power sources that are as small as the gadgets they're meant to drive, shrinking everything from jet engines to nuclear-power plants down to the size of silicon chips in the search for the perfect battery.

The first crop of such devices may hit the market next year. At the front of the pack are micro fuel cells, tiny versions of the hydrogen-fueled power plants often touted as the key to the automobile's future. A fuel cell is something like a battery that runs on replaceable fuel, typically taking in hydrogen and sending it through a membrane that screens out electrons, forcing them into a circuit where they can do electrical work. Now, thanks to micro-manufacturing techniques, 50 or so companies are working on fuel cells as small as matchboxes that might power a portable device for a day or more.

One of those companies is Medis Technologies, an Israeli firm that next year plans to introduce a 200-gram, $15 fuel cell capable of recharging a cell phone or digital camera up to five times on a ration of fuel. The first version will be disposable, but others will accept a $2.50 refill cartridge. "It will be like walking around with a wall outlet, except it's smaller than a fist and weighs almost nothing," says Medis CEO Robert Lifton.

As soon as next year fuel cells will come built into the lids or bases of laptop computers; Motorola, Samsung and Toshiba ...