Solid-oxide fuel cells can generate electricity using a range of readily available fuels. But because they run very hot--often above 1,000 ºC--they typically require insulation that makes them bulky. A new version employs an insulation technique that keeps the finished device as small as a pack of playing cards. The gadget, which could help keep electronic devices humming on long flights or hikes, runs on cheap butane cartridges; one cartridge packs enough power to recharge a smart phone 20 times. Swap out the cartridge, and it's ready for 20 more charges. The device is scheduled to go on sale next year.

Credit: Christopher Harting

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