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Google Science Fair Finalist Invents Peltier-Powered Flashlight
GTRacer writes "Ann Makosinski, a Canadian student competing in Google's Science Fair, submitted a flashlight which uses temperature differentials to power its LEDs. Her long-time interest is alternative energy because, '[she's] really interested in harvesting surplus energy, energy that surrounds but we never really use.' Using Peltier tiles and custom circuitry, her design currently runs for 20 minutes or so and costs $26. A win at the September finals in Mountain View and/or outside investment could fund further development."
So if you're hanging around the desert and the ambient temp is warmer than your hand, will it make things darker? That would be cool.
-- "Oh. This guy again."
Makosinski admitted there were points in the experiment when she thought it would never work, but said "You just kind of have to keep going.
Way more important lesson than the circuit design.
Being able to get light out of such a tiny current source as a thermocouple is amazing. Since it's just two dissimilar metals in electrical contact to provide the electricity there's plenty of scope to improve the design and get something mass produced for a lot less than $26.
The summary may confuse people since they may be thinking of peltier cooling, which is providing electricity to create a temperature difference, but the same hardware produces electricity from a temperature difference (and is normally known as a thermocouple in that mode).
She's from Canada, so there's likely a pretty massive delta between the ambient air temperature and human body temperature. It, like elections, probably doesn't work in Florida.
Does she put it in the fridge before using it or something? Or does it use the difference in temperature between your hand and the flashlight.
The latter.
If you RTFA you'll see she's using the aluminum flashlight body as a heat conductor and the "head" and other exposed portions of it as an air-cooled heatsink.
She's stuck the handle of the light into an insulating plastic pipe, cut a hole in the pipe, and stuck the peltier cell in the hole, with the "cold" side in contact with the flashlight handle and the "warm" side in contact with the hand. (I expect the next step is to wrap an outer aluminum tube around it to conduct heat from the whole hand to the cell, rather than just heating it with a patch of palm directly contacting it.)
Voltage boost converter between the peltier assembly and the LED (because the peltier cell she used was not stcked for the right voltage to drive the LED.) The LED shines as long as you hold it, if the air is cool enough. (She's used it for 20 minutes running.)
Also, since this is generating electricity from a temperature differential, rather than generating a temperature differential from electricity, wouldn't this be the Seebeck effect?
Yes. Seebeck discovered current generation from heat differential (with dissimilar metal wires and a compass needle), then Peltier discovered heat-pumping with current.
But, like most rotating electric machinery (where the same device is a motor or generator depending on whether you power it or twist it), the same effect is a heat pump or heat engine (depengding on whether you apply a temperature difference and pull power or apply power and pump heat).
The effect is now often called the "Peltier-Seebeck effect" in textbooks. The cells are typically called Peltier Cells because the efficient ones are manufactured mainly for heat-pumping, though they work just fine both ways.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
The thing her presentation is missing is any acknowledgment that she has actually learned something, and realizes now that her flashlight is a neat little science trick, but otherwise terribly impractical.
It only works for a few minutes, as the flashlight heats up to match your body temperature, and wouldn't work at all where ambient temps are remotely similar to body temperature. She also got only a tiny amount of power and light out of it, which could be provided for weeks or months by a watch battery without the expensive peltier in the mix.
Slightly more interesting than vinegar and water mixed together in a model volcano, but the real question is whether she learned something valuable in all of this.
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This is how it starts.
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She "invented" it by finding an circuit online, copying it, and buying some Peltier tiles off of eBay? WTF?
This stupid girl just did what every working engineer does - even the NASA engineers - take shit off the shelf and design from it!
If she was REALLY smart, she's mine her own copper, done her own research, discovered chemistry and physics on her own, and well, just did it without all this nonsense of living in an industrial society!
REAL inventors reinvent in the wheel everytime they need one!
She said she's getting about 5mw of power from it, which sounds pretty decent from just a 5 degC temperature differential *and* using circuitry to increase the voltage. Should be quite visible in the dark, even enough to read from if held close to a book. At least until the aluminum heats up from her hand and the hole in the middle turns out to be inadequate to sink enough heat to maintain the temperature differential under most conditions (though she's in Canada, so maybe that's not such a problem there :-) ).
In comparison typical 2000mAh alkaline AA cell can support 5mw for about 600 hours, but if you can't afford alkaline batteries (or are someplace where you don't have easy access to them), then this flashlight may be better than nothing. Though a crank-up generator flashlight might be brighter and more usable.
It may not save the world, but it's a great science fair project.
She "invented" it by finding an circuit online, copying it, and buying some Peltier tiles off of eBay? WTF?
Yeah, and if you think that's bad, you should see how Intel does pretty much the same thing and they are making billions of dollars off of it! All they did was look up a transistor design from 50 years ago, hook up billions of them in an integrated circuit, stamp their name on it and sell it for hundreds (or even thousands!) of dollars to unsuspecting users that could have built it themselves if they wanted to.
Losers! (sorry for the correct spelling, stupid autocorrect didn't let me type Loosers!")
I can not believe the comments I am reading here. There are initiatives all over the world to get more females into STEM stuff and everyone here seems to quibble about the technical details! She's a teenager. I first learned about the Peltier effect in my 4th year at University, yes that was 40 years ago. My kids didn't learn about it in their High Schools either. So much for the U.S. education system. Give the kid a break!
Losers! (sorry for the correct spelling, stupid autocorrect didn't let me type Loosers!")
Wait a minute.
Dude, in a few years she'll be doing great things and you'll still be living in your parents' basement wishing you had an organic girlfriend.
My God, it's Full of Source!
OUTSIDE_IP=$(dig +short my.ip @outsideip.net)
She just invented a new flashlight, and wants to use "energy that surrounds but we never really use."
Like, the energy that surrounds us and penetrates us, and binds the galaxy together? Her "long time interest" is clearly building a light saber.