Reposted from inhabitat.com:
by Mark Boyer, 07/02/13
From a sleeping bag that charges your gadgets to entire buildings heated by body heat, scientists are harvesting the heat emitted by humans as a source of renewable energy. But the latest development in thermoelectric energy generation doesn’t come from a high-tech lab at MIT; it comes from Ann Makosinski, a 15-year-old Canadian girl who developed a flashlight that is powered by the heat from a human hand. With the aim of reducing the number of single-use batteries that are thrown in landfills, Makosinski developed the innovative flashlight, which can be developed cheaply and deployed to populations that can’t afford electricity to light their homes.
To create the thermoelectric flashlight, Makosinski used Peltier tiles, which produce electricity when heated on one side and cooled on the other. Makosinski fashioned the flashlight out of an aluminum tube housed in a PVC tube with an opening to allow a person’s hand to come into contact with the Peltier tiles. “My design is ergonomic, thermodynamically efficient, and only needs a five degree temperature difference to work and produce up to 5.4 mW at 5 foot candles of brightness,” explains Makosinski.
The Peltier tiles transfer heat from a human hand to power an LED bulb that is bright enough to use in a flashlight. The Peltier tiles rely on temperature differential to work, so the light burns brighter when it’s colder outside.