Body-heat powered flashlight

A hollow flashlight powered by the heat from a user's hand, designed by a 15-year-old girl from Victoria, has been picked for the finals of the Google Science Fair.

http://www.cbc.ca/news/technology/s...oogle-science-fair-finals-ann-makosinski.html

is this how the world of The Matrix starts?

Amazing, that is very interesting. Thanks for sharing

I had just mentioned that article to my wife. Sounds like the girl spent quite a bit of time researching things - more power to her.

John.

Good idea using [what I call] a Peltier cooler, in reverse. And she took the time to figure out a circuit to boost the voltage. Very admirable for someone so young. I see a future CPF member!

A big "well done" to the young lady.

I wonder if a small fan would increase the cooling enough to offset the energy it consumes, or more.

That is a pretty neat device that she created. There is something similar in the outdoor community that generates power by burning combustible items and then converting the heat into electricity that charges an internal battery that can then charge electronic components.

Phantom309 said:

I wonder if a small fan would increase the cooling enough to offset the energy it consumes, or more.

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I'm going to say no. Using current themoelectric devices, I don't know that such a small delta T is sufficient to even power a small fan. And if it is, it would probably not leave much (if anything) for lighting. That's part of the problem with the aforementioned biolite stove - it uses most of the power it generates to run a fan (required to cool the module and provide air for the fire). This leaves you with only about 2W for such things as charging phones.

I should mention, though, that last fall, a specially treated lead tellurium alloy was found that GREATLY increases the efficiency of thermoelectric devices. Current thermoelectic devices are about 3-5% efficient with a decent delta T. The new alloy apparently increases this to 15-20%, which is a HUGE jump. Not sure when (or if) this might ever find its way into commercially available products. But if it ever does, it would GREATLY improve the performance of a light such as this one (not to mention LOTS of other things).

Absolutely fascinating! Thanks, Yamabushi, for bringing that to our attention. The neat thing is that it works better in cooler temperatures, and typically it's cooler at night, just when you'd want to use the light.

I want one .

Derek Dean said:

Absolutely fascinating! Thanks, Yamabushi, for bringing that to our attention. The neat thing is that it works better in cooler temperatures, and typically it's cooler at night, just when you'd want to use the light.

I want one .

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That's called Carnot Efficiency. Thermoelectric modules are actually a type of engine. But instead of generating physical work, they generate electricity. However, as with all engines, you increase the efficiency by either increasing the temperature at which you give it heat, decreasing the temperature at which it is taken away, or (preferably) both.

A couple more things to consider. In a dry climate, performance could be improved by spraying the heatsink with water or perhaps having a soaked, porous material (like cloth) in contact with it. The evaporative cooling would improve heat loss. Also, if the air temperature is GREATER than body temperature, the voltage from the modules will reverse in polarity. However, even if you have diodes to reverse it back, the delta T will probably be too small to generate sufficient power.

Great! Great flashlight, Great the young girl. thanks for sharing.

That is a really great story about a great idea. Thank you for sharing it!

blah9 said:

That is a really great story about a great idea. Thank you for sharing it!

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The concept of using thermal body heat to power a flashlight is not new, but the embodiment with interior metal tube insulated from the hand with one contact point for the hot side is interesting. That provides a thermal mass for the cold side that makes the concept work. It would be interesting to see at how high an ambient temp it does work. They discuss 5 and 10C, but not warmer. The article said that it provided steady light for 20 minutes. I wonder if this was the limit of the test or that was the point at which the interior tube became too warm for the system to function?


It was noted in the comments that her father does list micro-energy harvesting and miniature electronics as two of his specialties. His does have a B.A. in Arts, but also lists electronics as part of that education. I wonder who inspires who in that family?

Semiman

SemiMan said:

I wonder if ... that was the point at which the interior tube became too warm for the system to function?

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That's the advantage of being in Canada ... we have plenty of ice and snow.

http://www.youtube.com/watch?v=9CCGUMkcbjg

She is rather long winded and only demonstrated at the end. Around the 1:45 mark. The sound is rather low. Boost your volume control if you want to listen to her.

5 foot candles/candlepower seems too low for practical applications today, but it's a start. Seems like a better idea than the shakelights at least.

Another Vid.

LED Flashlight powered by body heat, no batteries!

Its called the Ann's Hollow Flashlight, created by a 15yo Canadian student. Hopefully she patents this thing before others start copying her ideas! Looks like a Triple P60 drop-in from Malkoff in an Oveready Cerakoted host...:thumbsup:

Re: LED Flashlight powered by body heat, no batteries!

Thanks Norm!

Re: LED Flashlight powered by body heat, no batteries!

This would mean that a flashlight left in the car could actually be used to charge external batteries. correct me if I'm wrong, but doesn't peltiers have less than 10% efficiency?