This body heat powered flashlight was invented by Canadian 10th grader Ann Makosinski. Using no batteries, electricity, or cranking, just the difference between her warm hand on metal and the colder air flowing through a hollow plastic tube, the heat energy difference (thermoelectric effect) lights up the LED bulbs.
Ms. Makosinski is a finalist this year in the worldwide Google Science Fair. Take a look at her simple and practical flashlight design.
Thanks to Gizmag for this article.