LED converts heat into light +200%.efficiency

A light-emitting diode (LED) that emits more light energy than it consumes in electrical energy has been unveiled by researchers in the US. The device – which has a conventional efficiency of greater than 200% – behaves as a kind of optical heat pump that converts lattice vibrations into infrared photons, cooling its surroundings in the process. The possibility of such a device was first predicted in 1957, but a practical version had proved impossible to create until now. Potential applications of the phenomenon include energy-efficient lighting and cryogenic refrigeration.

Article

Surprised this hasn't been posted already as it seems to be a major breakthrough in the field of energy. With all the free energy talk lately this is one of the few that's backed up with hard scientific data and there's even a solid theory behind it. Diodes are very well known devices and great advancements have been made in their production so this might get commercial quite quickly.
Even though the experiments currently are in the picoWatt range, if researched and optimized further this could put the energy range in what we're used to and probably also increase its efficiency further. I hope this blows up just like semiconductors did in the computer world but now for the energy world instead.

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200% efficiency? I'd like to see that, literally

I wonder how it works, its kind of hard for my mind to grasp. Will read the source article soon.

Wait, cryogenic? Isn't the reason that doesn't work is because as we get below freezing our body liquid expands and we kinda explode?

Does this not break a the basic laws of Thermodynamics? I mean 100% in and 200% out????

reply to post by calnorak


Basically "the heat from the lattice" or in other words the "temperature" that the device has due to the ambient temperature is used to generate additional light (photons). This conversion of ambient heat to light will hence cause the cooling of the nearby environment, that's the device in a nutshell. So far most research has been focusing on increasing the voltage of when a LED starts to conduct and emit light but this research suggest the opposite had to be done in order to observe a measurable effect.

Don't get overexcited. The article states that it is a optical heat pump, is driven by a heat source. The term efficiency is maybe badly chosen. They call it "wall-plug (i.e., power conversion) efficiency" in the original paper. Maybe COP would be a better fit. The output levels are in the range of pico-watts.

Originally posted by andy06shake
Does this not break a the basic laws of Thermodynamics? I mean 100% in and 200% out????

edit on 9-3-2012 by andy06shake because: (no reason given)

It's converting the heat out of the air into light, supposedly. So really no energy is magically gained, or anything, it's just taking one kind of energy (heat) and turning it into another (light).

Pretty nifty, assuming this really works. I'd like to see it in action.

It's not easy to find the radiant efficiency for LED's. But from the little research that I have done I discovered that most LED's have a radiant efficiency of around 1-10%. That is to say that 1-10% of the input energy is radiated as light energy. So a radiant efficiency of +200% is very impressive indeed.

Still something is strange.

Think of a hot closed box. Place one of this 200% LEDs into it and connect it to a 75% efficient photo-voltaic cell which is fed by LED photons.

The photo-voltaic cell would drive the diode with 200% * 75% = 150% and the diode would cool the box at same time. One could capture the extra 50% for external usage to keep the system from running away. Violation of the second law.

Where is my error?

reply to post by moebius


There's no error in your reasoning the box should indeed cool down as more and more photons are created. But I can only quote the article.

At first glance this conversion of waste heat to useful photons could appear to violate fundamental laws of thermodynamics, but lead researcher Parthiban Santhanam of the Massachusetts Institute of Technology explains that the process is perfectly consistent with the second law of thermodynamics. "The most counterintuitive aspect of this result is that we don't typically think of light as being a form of heat. Usually we ignore the entropy and think of light as work," he explains. "If the photons didn't have entropy (i.e. if they were a form of work, rather than heat), this would break the second law. Instead, the entropy shows up in the outgoing photons, so the second law is satisfied.

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reply to post by moebius


Show me a photovoltaic cell with 75% efficency and your private isle in the pacific, as I'm sure you would have both if you had a real cell like that.. No, just kidding. You would be dead.

Okay, now I'm serious: There is no cell with 75% - take a third of that, that is a viable option.

reply to post by andy06shake


Thermodynamics old skool...

Originally posted by ManFromEurope
reply to post by moebius

 

Show me a photovoltaic cell with 75% efficency and your private isle in the pacific, as I'm sure you would have both if you had a real cell like that.. No, just kidding. You would be dead.

Okay, now I'm serious: There is no cell with 75% - take a third of that, that is a viable option.

Ahem......

The new NREL cell shatters the quantum efficiencies of previous designs, posting a peak external quantum efficiency of 114 ± 1% and a peak internal quantum efficiency of 130%.

LINK

reply to post by ManFromEurope

Just playing with numbers as I don't know the limits. Take a 500% led + 25% photo cell -> 125%. There must be some conceptual error.

My guess is that the temperature dependency of the photo cell(semiconductor) won't allow such construction.

Or does anyone remember this?

nantennas: capture 95 percent of solar energy

From what I remember the main issue was building terrahertz frequency diodes to rectify the current, wonder how far they're on that. But nantennas would actually be the most ideal electricity converter for this "cool diode". As the diode emits a very specific wavelength nantennas are nano sized antennas for very specific wavelengths as well, a match made in heaven .

reply to post by ken10


Are you talking about the ratio between generated current and received current? Because that is not the ratio between solar impulse and generated current - which is about 40% in research-level-cells. In the field, you can find about 25-28% afaik.

Originally posted by ManFromEurope
reply to post by ken10

 

Are you talking about the ratio between generated current and received current? Because that is not the ratio between solar impulse and generated current - which is about 40% in research-level-cells. In the field, you can find about 25-28% afaik.

No idea really, all the info is in the link.

I always thought anything over 100% efficiency was over-unity

Originally posted by ken10

Originally posted by ManFromEurope
reply to post by moebius

 

Show me a photovoltaic cell with 75% efficency and your private isle in the pacific, as I'm sure you would have both if you had a real cell like that.. No, just kidding. You would be dead.

Okay, now I'm serious: There is no cell with 75% - take a third of that, that is a viable option.

Ahem......

The new NREL cell shatters the quantum efficiencies of previous designs, posting a peak external quantum efficiency of 114 ± 1% and a peak internal quantum efficiency of 130%.

LINK

AHEM From your own link above!!!!

This means that the overall conversion efficiency (CE) of a traditional cell -- even if perfectly optimized -- would not exceed 32 percent.

It also says this

Overall this could grant up to a 35 percent efficiency gain versus today's standard PS silicon cells, according to the paper's authors.

Originally posted by moebius
Still something is strange.

Think of a hot closed box. Place one of this 200% LEDs into it and connect it to a 75% efficient photo-voltaic cell which is fed by LED photons.

The photo-voltaic cell would drive the diode with 200% * 75% = 150% and the diode would cool the box at same time. One could capture the extra 50% for external usage to keep the system from running away. Violation of the second law.

Where is my error?

Your error is as follows: Say the LED draws 10W and outputs 20W of light, at least 10W of heat has been input, probably much more. So with a 95% efficient PV cell, 19W of electrical power is produced. 10W of that is required to power the LED, leaving only 9W for the heater, which isn't enough.

It is basically a heat pump, which are typically greater than 100% efficient. I guess that a future version of this wont need the heater but again it is just like a heat pump if it uses heat from the environment.

a self cooling LED is a nice touch, isn't it? The unexpected downside is of course that they would only emit half as much light in the cold, so better use them indoors.

Now imagine a reversal of the principle: a light powered freezer (airconditioning), but i doubt that one will be as simple as it sounds.

reply to post by Long Lance


Actually, if I'm understanding this correctly, you would simply have the backpane the diodes are connected to be the heat-exchanger of the insulated box we call a refrigerator/freezer. You would, then, pipe the photons away via fiber optics and use them for lighting of some sort (perhaps, if they are of the proper wavelengths, into a hydroponics setup).

I never thought solid-state cooling would come from LEDs... that segment has been largely dominated by the Peltier junction... which is a little different, as it isn't a heat-pump... but still nifty.