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Today I have learned that Peltier devices can be used to generate electricity.

I have a set up with a 50 watt LED which is glued to a very large heat sink that cools it without any fans (that can dissipate up to 100w).

The idea of being able to sandwich the Peltier between the LED (heat source), and the large heat sink (cool surface) to generate current sounds awesome.

Before I order a 60w Peltier device off eBay, I'd like to ask:

Can I safely place this Peltier between my LED and heat sink to:

  1. Generate electricity through the difference in surface temperature (LED bay and heat sink)?

  2. Will my set up still work without trouble (LED works fine and heat sink still cools it down)?

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2 Answers 2

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Your 50-watt LED requires a heatsink, because otherwise it would overheat and destroy itself. The temperature of the LED is directly related to the thermal resistance between the LED chip inside the package, through the heatsink, to the ambient air.

Your Peltier device will add a considerable amount of thermal resistance to this path, which means that your LED will run much hotter with it than without it. This is probably not a good idea.

Furthermore, Peltier devices are not very efficient at converting heat flow to electricity. If you need electricity for some reason, you'd be better off tapping what you need from the LED power supply itself.

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  • \$\begingroup\$ Thank you very much for this explanation. It makes sense. I can not decide however whose answer I should accept, since both are the same and written pretty much at the same time :-) \$\endgroup\$
    – Phil
    Mar 11, 2015 at 13:21
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1) Yes, although not a lot of electricity, maybe a few watts.

2) Probably not. The Peltier device is necessarily much worse at heat conduction than the heatsink itself when you're using it to generate electricity - the work done in pushing heat across the thermal gradient is the energy extracted.

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  • \$\begingroup\$ Thank you very much for this explanation. It makes sense. I can not decide however whose answer I should accept, since both are the same and written pretty much at the same time :-) \$\endgroup\$
    – Phil
    Mar 11, 2015 at 13:21

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