# 230% Efficient LEDs



## pretmetled (Mar 12, 2008)

AnAppleSnail said:


> Please read my post which attempts to explain what is happening in a way people without expertise in quantum physics can understand.


 
If you mean the post right above in this thread, then yes I read it since it's right above in this thread.



> Thermal energy can be converted to photons, as can lattice vibrations.



Which is what the hot metal stick example was exemplifying. 

...

edit: now why is this post suddenly listed at top of thread?  .... editing post to hopefully "fix" that.


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## Mattaus (Mar 6, 2012)

***Apologies if this does not belong in this section of the forums, or if this is repeated news. I searched and could not find it posted previously.***

So some interesting news taken from Gizmodo but I saw it elsewhere yesterday:



> Light bulbs have always required more electricity than they need to produce light because the energy conversion process — changing electricity to light — was inefficient. But an MIT research team has just shown that an LED can actually give off more light than it consumes in electricity.
> Incandescent bulbs are the poster child of inefficient energy conversion. The devices heated a filament with an electrical current which not only produced light, but a lot of waste heat as well. Fluorescent bulbs, CFLs and even conventional LEDs all generate the same waste heat to varying (albeit much smaller) degrees but none has ever reached 100 per cent efficiency — a mark known as “unity efficiency”.
> 
> 
> ...



One day it will hopefully be a bit brighter :thumbsup:

- Matt


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## mvyrmnd (Mar 6, 2012)

So if we run 100 billion XP-G's at 30 picowatts a piece, we'd be getting 6.9W of light for 3W of electricity. I think. That many zeros messes with my brain.


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## precisionworks (Mar 6, 2012)

> the team was able to generate 69 picowatts of light



69 X ( 10-12​ ) watts. Or .000000000069 watts.


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## Th232 (Mar 6, 2012)

If the extra energy comes from the thermal energy in the bulb (waste or from its surroundings), I can see this going well in warm countries. People in colder climates will to turn up their heaters a bit more though...


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## Mattaus (Mar 6, 2012)

Th232 said:


> If the extra energy comes from the thermal energy in the bulb (waste or from its surroundings), I can see this going well in warm countries. People in colder climates will to turn up their heaters a bit more though...



So what you're saying is that we'll be right here in (mostly) sunny Australia. :nana:

It's a step in the right direction at least. The speed at which most things are advancing is insane these days, and just about the only thing that is not moving as fast as everything else is batteries. So we need to get more efficientl, though it wouldn't harm anyone if both improved hand in hand.


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## StarHalo (Mar 6, 2012)

I wonder if 69 picowatt emitters would work in night vision display equipment..


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## Th232 (Mar 6, 2012)

Mattaus said:


> It's a step in the right direction at least. The speed at which most things are advancing is insane these days, and just about the only thing that is not moving as fast as everything else is batteries. So we need to get more efficientl, though it wouldn't harm anyone if both improved hand in hand.



You just made me realise something. My titanium lights with their lower thermal conductivity will perform better than my Al lights, which will take away all that valuable heat from the LED and waste it heating the surrounding air. That would be really funny to see.


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## RoGuE_StreaK (Mar 6, 2012)

So does that mean we should throw away our heatsinks?

Not sure how they "harness" the waste heat; maybe uber-micro stirling engines?


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## Mattaus (Mar 6, 2012)

Th232 said:


> You just made me realise something. My titanium lights with their lower thermal conductivity will perform better than my Al lights, which will take away all that valuable heat from the LED and waste it heating the surrounding air. That would be really funny to see.



Actually the heat sinking practices we currently all strive to implement would become null and void...flashlight design would/could change dramatically. I am of course only thinking about flashlight applications here. I'm sure there are many more far reaching implications.


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## StarHalo (Mar 6, 2012)

69 picowatts isn't enough for any sort of lighting application..

But if you can indeed see very few or individual photons in total darkness, as has been posited here, then a bunch of these micro-output micro-LEDs could work in night vision display of some sort..


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## AnAppleSnail (Mar 7, 2012)

StarHalo said:


> 69 picowatts isn't enough for any sort of lighting application...


I dunno, you'd only need about 21 million of these to produce almost a whole lumen in green light.






​


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## TEEJ (Mar 7, 2012)

There ARE some members here who would BUY a light that put out a 1/21,000,000 lumen "Firefly" mode.



And there would be some others who would complain THAT'S too bright.


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## StarHalo (Mar 7, 2012)

AnAppleSnail said:


> I dunno, you'd only need about 21 million of these to produce almost a whole lumen in green light.



Your average low-res camera display has about 200,000 pixels in it; that would be .01 lumens total by the math, which would be absolutely visible in total darkness..


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## TEEJ (Mar 7, 2012)

StarHalo said:


> Your average low-res camera display has about 200,000 pixels in it; that would be .01 lumens total by the math, which would be absolutely visible in total darkness..



How do you know that 0.01 lumens, spread out over an unknown area, would be visible?

It would essentially have to be concentrated enough to put lux on something to see.

Or do you mean you see an application for a light source the size of a 200k pixel camera display working as some sort of 0.01 lumen indicator light, as in the screen sized source would glow faintly, and that would be useful because you could see it if it were otherwise pitch black, and your eyes were night adapted?



I think we can just wait for cold fusion...it should be ready any time now...


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## StarHalo (Mar 7, 2012)

As in a display, you're staring into the emitters; a 0.01 lumen total display should be plainly visible to dark adjusted eyes..


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## fyrstormer (Mar 8, 2012)

It sounds like it works similarly to laser cooling; when the metal's electron-plasma field is vibrating at its resonant frequency, any input energy increases the brightness of the light emitted -- even if that energy comes from the temperature-induced random vibration of the metal's nuclei.


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## AnAppleSnail (Mar 8, 2012)

fyrstormer said:


> It sounds like it works similarly to laser cooling; when the metal's electron-plasma field is vibrating at its resonant frequency, any input energy increases the brightness of the light emitted -- even if that energy comes from the temperature-induced random vibration of the metal's nuclei.


I didn't see information about what wavelengths are emitted. Are their lattice vibrations "useful" light, or are we talking infrared warming of an LED here?


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## fyrstormer (Mar 8, 2012)

I'm not sure you can get useful light at _any_ wavelength with an input power of 69 picowatts.  Pragmatism aside, as far as I know an LED will *always* produce its intended color of light as long as the drive voltage is within spec, regardless of how tiny the amperage may be.


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## znomit (Mar 9, 2012)

We need to know how big the die is. I'm thinking a few trillion of these mounted to my ceiling to provide light and cooling. 

Should save me a few bucks in power.


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## monkeyboy (Mar 9, 2012)

mvyrmnd said:


> So if we run 100 billion XP-G's at 30 picowatts a piece, we'd be getting 6.9W of light for 3W of electricity. I think. That many zeros messes with my brain.



Interesting idea. Back-of-the-envelope calculation:

You'd need an area of 1.5 km x 1.5 km and more money than Bill Gates. Not sure you'd even be able to see a dim glow with 6.9W spread over that area. Imagine the cabling you would need and the power losses through that length of cabling!

How about this for an idea: put the die in contact with an efficient photovoltaic solar cell which simultaneously powers the die and extracts energy from it, and you have a machine that extracts heat from the environment and directly produces electricity. I'm sure that violates every law of thermodynamics though.


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## mvyrmnd (Mar 9, 2012)

monkeyboy said:


> How about this for an idea: put the die in contact with an efficient photovoltaic solar cell which simultaneously powers the die and extracts energy from it, and you have a machine that extracts heat from the environment and directly produces electricity. I'm sure that violates every law of thermodynamics though.



It would only break the rules if it ran forever. With no external input of power after the initial power up, it would simply fade out over time.


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## uk_caver (Mar 9, 2012)

monkeyboy said:


> You'd need an area of 1.5 km x 1.5 km and more money than Bill Gates. Not sure you'd even be able to see a dim glow with 6.9W spread over that area. Imagine the cabling you would need and the power losses through that length of cabling!


If starlight is ~10^-4 lux(10^-4lm/m^2), with white light at ~350lm/W the 6.9W of light would be 2400lm, spread over the 1.5x1.5km, about 10x as bright as starlight, if I haven't screwed up calculations.


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## AnAppleSnail (Mar 9, 2012)

fyrstormer said:


> I'm not sure you can get useful light at _any_ wavelength with an input power of 69 picowatts.  Pragmatism aside, as far as I know an LED will *always* produce its intended color of light as long as the drive voltage is within spec, regardless of how tiny the amperage may be.



They say they have an LED with a "very small band gap." To me that means low-energy photons. ie, they have produced an infrared LED emitting 'bonus' infrared light.


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## uk_caver (Mar 9, 2012)

If so, when they say '_these initial results provide too little light for most applications_', I wonder what applications there _would_ be for a very dim infrared LED?


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## jtr1962 (Mar 9, 2012)

My take on all this isn't that the LEDs in the experiment have any practical applications, but rather that the experiment helps to understand where the losses occur. This in turn could eventually lead to LEDs which are nearly 100% efficient. Once you get past 75% or 80% efficiency, small gains may not save you much power, but they could greatly decrease heat-sinking requirements. Going from 80% to 90% cuts your heat-sinking requirements roughly in half. Going to 95% cuts them in half again.


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## AnAppleSnail (Mar 9, 2012)

uk_caver said:


> If so, when they say '_these initial results provide too little light for most applications_', I wonder what applications there _would_ be for a very dim infrared LED?


Either removing a few picowatts from something inefficiently, or it's only mentioned because the science journalists misinterpreted things, or else I'm misreading what the band gap means.


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## fyrstormer (Mar 9, 2012)

uk_caver said:


> If so, when they say '_these initial results provide too little light for most applications_', I wonder what applications there _would_ be for a very dim infrared LED?


One application that comes to mind is a cooling surface for cryogenic experiments. The crystalline surface of the emitter would help the cryogenic substance radiate away its remaining heat.


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## ssvqwnp (Mar 9, 2012)

I think you guys are looking at this the wrong way... We could cover our existing LED heatsinks with these LED and let them run off the heat, that way we can lave LED-powered LED!



Yo dawg, I heard you like LED, so we put LED on your LED so your D can EL while your D EL's... (I'm new at this, forgive me)

Someone had to say it.


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## ma_sha1 (Mar 9, 2012)

...........


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## TEEJ (Mar 9, 2012)

uk_caver said:


> If starlight is ~10^-4 lux(10^-4lm/m^2), with white light at ~350lm/W the 6.9W of light would be 2400lm, spread over the 1.5x1.5km, about 10x as bright as starlight, if I haven't screwed up calculations.



You are assuming that ALL of the stars combined in the night sky are covering the ground with a given Lux


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## uk_caver (Mar 9, 2012)

TEEJ said:


> You are assuming that ALL of the stars combined in the night sky are covering the ground with a given Lux


Well, I was using generally given figures for illumination by starlight (presumably on a fully clear moonless night away from any artificial light), and I was assuming the figures I was progressing from were correct.
As far as the LEDs were concerned, the assumptions I was making included:
a) the output being visible light
b) a rough watt - lumen/lux conversion of about half the green optimum
c) a basically infinite illuminator, such as extensive LED-covered panels slung overhead much wider than they were high above me, such that the intensity of light hitting the ground was the same as the intensity of light leaving the emitting panels (so definitely nothing like a flashlight actually lighting an area much larger than its emitter to starlight-like levels).

The first one of which may be wrong, the second inaccurate, and the third impractical (though putting some kind of upper bound on the possible intensities of illumination)

Though it _was_ only an estimate to get some rough handle on the kind of light/energy levels involved.


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## Mattaus (Mar 9, 2012)

ssvqwnp said:


> Yo dawg, I heard you like LED, so we put LED on your LED so your D can EL while your D EL's... (I'm new at this, forgive me)
> 
> Someone had to say it.



Lol, don't worry ssvqwnp, I get what you tried to do there. Pretty good effort IMO.


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## pretmetled (Mar 10, 2012)

Yeah, ran into that article earlier on. Nice heat pump.


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## Lynx_Arc (Mar 10, 2012)

There is something wrong with the article. You don't measure light in watts at all and measurements for light have nothing to do with power itself so trying to say picowatts of light is meaningless because all they have done is proved that they can make more efficient light than thought before. They must have started with some sort of "idea" that so many watts = so much light which would indicate if they were correct in the first place that number would not be unable to be surpassed. In other words their experiment only proves that their "idea" of "watt of light" was incorrectly too low to begin with and they doubled the amount which to me means they were off 231% in their initial calcuations of "watt of light" to begin with.


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## AnAppleSnail (Mar 10, 2012)

Lynx_Arc said:


> They must have started with some sort of "idea" that so many watts = so much light



1 lumen = "1 lm = 1 cd*sr[URL="http://en.wikipedia.org/wiki/Steradian"]"[/url] and 1 cd is "the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012​ hertz and that has a radiant intensity in that direction of 1​⁄683​ watt per steradian."

Light, like sound, can be expressed as an amount of energy. Doing so accurately may be harder than I thought, but it is done.


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## Lynx_Arc (Mar 10, 2012)

AnAppleSnail said:


> 1 lumen = "1 lm = 1 cd*sr[URL="http://en.wikipedia.org/wiki/Steradian"]"[/url] and 1 cd is "the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012​ hertz and that has a radiant intensity in that direction of 1​⁄683​ watt per steradian."
> 
> Light, like sound, can be expressed as an amount of energy. Doing so accurately may be harder than I thought, but it is done.


I still stand with the notion you cannot get energy from nothing. There is no such thing as 230% efficiency unless you have a baseline to start with that is not truly 100% efficient. The laws of thermodynamics do not include energy being created from nothing at all which is what this "discovery" to me seems to be concluding innaccurately. I somewhat doubt they are using this formula to get their energy (in watts) from but instead basing it upon a standard of light output (in watts) based upon a known not 100% efficient energy source and comparing it with that. If they were using a 40% efficient light source then achieving nearly 100% efficiency then they would achieve this 230% figure.


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## pretmetled (Mar 10, 2012)

Lynx_Arc said:


> There is something wrong with the article. You don't measure light in watts at all and measurements for light have nothing to do with power itself so trying to say picowatts of light is meaningless ...



Wut?

I guess that all those laser output specifications in Watt are meaningless then. 

Translation: measuring light output (you know, photons schmotons) in Watt is perfectly valid.


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## Lynx_Arc (Mar 10, 2012)

pretmetled said:


> Wut?
> 
> I guess that all those laser output specifications in Watt are meaningless then.
> 
> Translation: measuring light output (you know, photons schmotons) in Watt is perfectly valid.


I don't see it being done by LED manufacturers.... it is lumens/watt..... not just watts. I still think this 230% is bogus because if something is totally efficient it is 100% at best anything over that means (via the laws of thermodynamics) that you must have energy being introduced from some unknown source (miracle).


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## pretmetled (Mar 10, 2012)

Lynx_Arc said:


> I don't see it being done by LED manufacturers.... it is lumens/watt..... not just watts. I still think this 230% is bogus because if something is totally efficient it is 100% at best anything over that means (via the laws of thermodynamics) that you must have energy being introduced from some unknown source (miracle).



Random google hit du jour:

http://www.cree.com/products/pdf/XLampXT-E_ROY.pdf

Page 6, radiant flux specified in mW.

As far as I'm concerned the penchant for using lumens has everything to do with convention in a particular business (lighting) and nothing with it's merit over SI _base_ units (as opposed to derived units).

Case in point: I've noticed that for royal blue leds it's quite customary to specifify radiant flux in Watt. And for regular boring blue leds that are the same in every respect (except for a few nm in wavelength  ) then suddenly lumens is all the rage.

Anyways, the 230% claim is rather arbitrary if you ask me since it's as open loop as you can get. But thermodynamically speaking there's nothing magical going on there. It's analogous to pumping up hot water and then stuffing it through a generator. Suppose the pump etc is 100 Watt and you can load the generator output by 230 Watt then your clever marketing monkeys can say "tada! 230% efficient! ^_^" in exactly the same way as these guys are doing.


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## Mattaus (Mar 11, 2012)

pretmetled said:


> Anyways, the 230% claim is rather arbitrary if you ask me since it's as open loop as you can get. But thermodynamically speaking there's nothing magical going on there. It's analogous to pumping up hot water and then stuffing it through a generator. Suppose the pump etc is 100 Watt and you can load the generator output by 230 Watt then your clever marketing monkeys can say "tada! 230% efficient! ^_^" in exactly the same way as these guys are doing.



I'm hungover and running on 3 hours sleep. I am an engineer so I _should_ understand this but I'm struggling right now. Can you break this down a bit? It looks like it makes sense to me, but I want to be sure lol. When I posted the article above my first thought was how could it be 230% efficient without bringing out all the free energy crazies? I was waiting for someone to explain it well and your heat pump analogy seems pretty solid...


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## uk_caver (Mar 11, 2012)

In terms of thermodynamics, how does electrical energy compare to electromagnetic radiation of various frequencies?

That is, is it theoretically possible to start off with some heat and some electrical energy and end up with less heat and more 'light' energy than the original electrical energy while still increasing overall entropy?


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## AnAppleSnail (Mar 11, 2012)

The MIT group is, fortunately, not claiming to violate the laws of thermodynamics. I'm trying a new list-based way to organize my replies, but it won't help if I'm reading these things wrong. Take this with a whopping grain of salt!

_1. Thermodynamics is a statistical study._
Everything moves, but it's hard to model this. One of my professors main interest is in modeling single molecules of complex biological things - like "When this protein folds, exactly how does it interact" or "What are the exact polymerization kinetics of Nylon 6,6?" In solids, the moving atoms can be modeled as a lattice of balls separated by springs. Kick one ball and its neighbors wiggle. This energy spreads through the substance in waves. Some is expressed as sound, some as light. We call these waves 'Phonons' because in their early study it was thought they were only sound. (Incidentally, one can calculate, quite accurately, the mass of a given metal's atoms with just the speed of sound in that metal).

_2. Warm objects vibrate, and this leads to interesting effects._
Pardon the Wiki Link: Phonon: Acoustic and optical phonons. Phonons are the vibrations of atoms in solids, and they can emit photons under certain circumstances met in many diodes. I THINK that this is what's happening: That they are measuring energy that is always emitted. The LED running at low power may regulate the wavelength of the phonon emissions, or I may be spouting complete crap.


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## pretmetled (Mar 11, 2012)

uk_caver said:


> In terms of thermodynamics, how does electrical energy compare to electromagnetic radiation of various frequencies?



I'm 230% sure I don't quite understand that question.



> That is, is it theoretically possible to start off with some heat and some electrical energy and end up with less heat and more 'light' energy than the original electrical energy while still increasing overall entropy?



Sure. I'll take your "some electrical energy" to mean a 9 Volt battery stolen from a passing energizer bunny. I will further take your "some heat" to mean a big stick of iron that has been conveniently heated to say 1500 Kelvin. Now during the experiment you hold up the heated iron stick, allowing it to radiate a couple Watts worth of photons. Then touch tip of tongue to 9 Volt battery. Et voila, several Watts worth of radiated photons, and only a couple uW used. Damn, now that's efficiency!

So as you can see, efficiency is all about the system definition.

PS: For a further increase in efficiency, do not lick battery.


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## AnAppleSnail (Mar 11, 2012)

pretmetled said:


> So as you can see, efficiency is all about the system definition.


Please read my post which attempts to explain what is happening in a way people without expertise in quantum physics can understand. Thermal energy can be converted to photons, as can lattice vibrations.


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## bshanahan14rulz (Mar 11, 2012)

monochromatic sources are easy to convert to mW. All the photons have the same energy. White light or mixed light is harder because each photon of a different wavelength carries a different amount of energy.


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## pretmetled (Mar 13, 2012)

Curious indeed.... this post was transported 4 years in the past and is now a pro-actove reply to the OP before the OP even thought about P-ing his OP. 

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AnAppleSnail said:


> Please read my post which attempts to explain what is happening in a way people without expertise in quantum physics can understand.


 
If you mean the post right above in this thread, then yes I read it since it's right above in this thread.



> Thermal energy can be converted to photons, as can lattice vibrations.



Which is what the hot metal stick example was exemplifying. 

...

edit: now why is this post suddenly listed at top of thread?  .... editing post to hopefully "fix" that.


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## Mattaus (Mar 13, 2012)

The date screws ups are because of the site being hacked a few days ago.


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## fyrstormer (Mar 15, 2012)

Okay guys, let's get one thing straight: when they say "230% efficient" what they mean is it's outputting 230% as much light as scientific models say it should given the amount of input electricity. The extra power is coming from ambient heat in the environment. As the LED draws heat out of the environment and the environment gets colder, the amount of light outputted will start to drop back down to what the scientific models say it should be.


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## Mattaus (Mar 15, 2012)

fyrstormer said:


> Okay guys, let's get one thing straight: when they say "230% efficient" what they mean is it's outputting 230% as much light as scientific models say it should given the amount of input electricity. The extra power is coming from ambient heat in the environment. As the LED draws heat out of the environment and the environment gets colder, the amount of light outputted will start to drop back down to what the scientific models say it should be.



Sounds about right. The extra energy has to come from somewhere!


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## zzonbi (May 10, 2012)

"Usually we ignore the entropy and think of light as work,"

So if light is not the work how is the led efficient at all? No work, no efficiency talk.

"They also heated the LED to 135 °C to provide more lattice heat. In this regime, less than 0.1% of the electrons passing through the LED produced a photon."

Did they account for the rest of 99.9% of current?
And keeping that high temperature in practice seems quite lossy.

http://www.candlepowerforums.com/vb...D-converts-heat-into-light-efficiency-gt-200-!

The basic idea is sound though, always x^2>kx after some point, so before that there should be more "light".


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