We need to learn how to make better batteries. Notebook computers shouldn't run out of juice on long flights, and handheld devices and cell phones shouldn't fail when you need them most. I suspect that battery limitations may keep some prototype products from reaching the marketplace.

Consider the work of IBM, which, with watch manufacturer Citizen Watch, has produced a prototype high-tech wristwatch called the WatchPad. It communicates via a Bluetooth chip that can connect to desktop or handheld computers, cell phones and other wireless-enabled gadgets. It offers e-mail and pager capability, a calendar program and a scheduler.

The statistics on this tiny unit are remarkable. It contains 8 MB of RAM and 16 MB of flash memory (a type of memory that can be re-programmed in blocks instead of one byte at a time). Its screen is a touch panel with 320 X 240 resolution using a monochrome liquid crystal display. Users can give the WatchPad voice commands to control other computers. For security, it provides a fingerprint sensor.

This futuristic watch sounds like a great idea -- until you realize that it only offers six hours of battery life, hardly enough to get you to lunchtime. Tinkering with the watch's Linux operating system should help, though the WatchPad will still need overnight re-charging in a cradle, just like a handheld computer. Presumably such charging time could also be used for synchronizing calendar items, to-do lists and other data with a desktop machine.

But surely the power options extend beyond charging cradles. How about powering devices by daily human activities?

That's the concept of an experimental boot developed by SRI International, a research company in Menlo Park, Calif. The heel of SRI's boot contains electroactive polymers, thin strips of elastic material with electrodes on opposite sides of the heel. As you walk, the polymers are compressed and released generating electricity that can be used right away or stored in rechargeable batteries.

Polymers -- chemical substances known for strength and flexibility -- are used in a variety of items, including car bumpers and bulletproof vests. But semi-conducting polymers are only now attracting attention. Like many technologies, the power boot grows out of work financed by the Defense Department, which has put $2.6 million into a larger SRI project known as Energy Harvesting. The idea is to help future foot soldiers carry fewer batteries for the increasingly high-tech tools they deploy in the field.

But work like this invariably moves into the public arena, and I can imagine power-generating shoes charging cell phones and handheld computers within a few years.

Don't forget solar power, either. Germany's Fraunhofer Institute has developed laptop and cell phone prototypes that use solar modules glued to the device. They can be charged even in faint sunlight or under a halogen lamp. We may start seeing this technology in the market in 2002.

On the rechargeable battery front, there is the good news that Brookhaven National Laboratory has developed a new alloy that eliminates the use of toxic cadmium (used in nickel-cadmium rechargeable batteries), and reduces battery cost at the same time. The alloy combines lanthanum, nickel and tin, offering high storage capacity and longer life through numerous charge and recharge cycles. It is also said to make batteries more resistant to corrosion.

In conventional batteries, the battery alloy disintegrates because of the wear caused by the charge-recharge cycle. Rechargeable batteries, we can hope, will be significantly improved by this breakthrough, leading to cell phones and other small devices that may retain their charge longer and boast significantly longer lifetimes. Power management might not be the most glamorous feature of high technology, but making progress will give us portable devices that truly begin to live up to their promise.

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