July 3, 2013 – Fifteen-year-old Ann Makosinski has invented something that will brighten your day and your house when the power goes out: a flashlight that is powered only by the heat of your hand!
Last year Makosinski, of Victoria, British Columbia, created a flashlight that used kinetic energy to power its LED lights, so she wanted to make a flashlight that could be powered by the energy produced by heat.
She became interested in harvesting extra energy when she realized that our bodies are always emitting heat, making them a great source of untapped energy.
First, she had to figure out how much energy the human palm can produce and how much she would need to power the LED lights. She measured that a palm can create about 57 milliwatts of heat and that the LEDs needed half a milliwat of heat to work.
Then, she got all the parts she would need for the flashlight to work. The key to the flashlight are Peltier tiles (tiles that produce electricity when one side is heated and the other side is cooled); she bought those on eBay and found a few other odds and ends she would need to make the energy current usable by the LEDs.
She wired the tiles and placed them in an aluminum tube. The air inside the tube cools the one side of the tiles while the heat from the holder's palm heats the other side. After making a few modifications Makosinski had a heat-powered flashlight!
The flashlight works by something called the thermoelectric effect; that's the name for harnessing energy as electrons flow between the cool and hot side of one material. One side of the flashlight is heated up by the holder's hand. When the heat is traveling through the Peltier tiles they quickly cool and create electricity that can power the LED lights!
Since the amount of heat emitted from our hands is fairly small the flashlight does not generate very bright light, but it can help you find your keys during a power outage or help keep you entertained by providing enough light to read a book during a black out.
In September Makosinski will be traveling to Mountain View, California to visit Google headquarters for their annual science fair. If her flashlight is chosen as the winner out of 14 other finalists she will win a $50,000 scholarship and a trip to Galapagos!