LED lights and heat production

[ateallthepies]

I was thinking that one thing that LED's do apart from light up is to produce a lot of waste heat.

Surely there must be a way to convert this waste heat back into electricity and re-charge the battery?

I remember an article about converting heat into sound then using the sound to activate a Piezo crystal into producing electricity?

How cool if someone could make a small enough unit to fit a flashlight and be able to partially re-charge itself with all that waste heat?

Steve.

 

[wantsusa]

Or a super small Rankine engine ROFL. I could just see it now a little reservoir of water with a tube in the heat sink heating up the water and running a little generator on the outside of the flashlight with a cooling area being the entire back of the flashlight.

I just read an article on how they want to try that type of stuff with hybrids and stuff. Expensive to do there and difficult so not likely to happen. I do remember in physics though that my professor talked about using the differences in temperature to create a current, wonder if it could create enough of a current to put a few super small LED's on the outside of a flashlight hehe.

 

[alpg88]

. I do remember in physics though that my professor talked about using the differences in temperature to create a current, wonder if it could create enough of a current to put a few super small LED's on the outside of a flashlight hehe.

i doubt it, i used thermoelectric elements before, they aren't that efficient,
in cases where you have huge heat waste, (exhaust systems, boilers...ect) than it makes sense, anything small, not really, those elements depend mainly on surface area, they are reversible, it can generate power, or heat\cold, for this they are used in most cases.
they are used in cpu cooling sometimes, and in those car coolers that you plug into cig. lighter. even some tiny fridges use those elements instead of compressors, freon...etc.

 

[Gunner12]

I recall a discussion on this before. By the end, the work gone through to extract the power from the waste heat would take up a good amount of room and also not be very efficient way to recover energy.

It is doable, but probably not practical. By the time it is practical, we'd probably be using much better LEDs, or another better light source. It'll still be cool to see though.

 

[qwertyydude]

One problem for the waste heat from an led is that if you slow the heat conduction by trying to extract energy from it you end up adding a layer of insulation to the heat path, this will raise the temperature of the hot side and this is bad for the led. Best way to increase the efficiency of the led system is to use more efficient led's.

Trying to extract energy from a process to add energy to the same very process is tantamount to perpetual motion.