As video telephony, broadband internet links and other high-powered features are added to laptop computers, personal digital assistants (PDAs) and mobile phones over the next few years, the energy demands of these devices will soar. The Samsung Advanced Institute of Technology, the research arm of the chaebol of that name, estimates that such upgraded portable devices will require power sources with at least 500 watt-hours per kilogram of energy stored in them. Lithium-ion batteries, today’s best, can manage half that, but even the most optimistic estimates suggest that only a 30% improvement could be squeezed out of such batteries.

But there may be an alternative. Miniature fuel cells, which generate electricity by reacting hydrogen with oxygen, can do much better than batteries—at least in a laboratory. The question is whether they can ever do so in the real world. This was the subject of a conference organised last week in New Orleans by the Knowledge Foundation.

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