http://phys.org/news/2012-03-efficiency.html

 

Apparently this device actually puts out more energy than it consumes, converting some of the ambient room temperature heat to light in the process.

How to calculate efficiency?

Edited August 9, 201213 yr by alpha2cen

light power out and electrical power in both measured in watts (picowatts). I cannot read the full paper but it seems the shortfall in electrical power input is made up by extracting heat from the surroundings via vibrations in atomic lattice.

Temperature dropping phenomena occurs?

Edited August 9, 201213 yr by alpha2cen

Temperature dropping phenomena occurs?

 

Yes. They appear to have been a little lax in using the term efficiency. I thought this came up when the article first appeared.

So, they've made a heat pump from a LED?

 

Heat pumps like in your fridge always >100% efficiency if you define efficiency in a silly way. Typically, they talk about the coefficient of performance, not efficiency.

So, they've made a heat pump from a LED?

It is not merely a heat pump. Heat pumps simply concentrate heat by transfering heat from one place to another.

The experiment that the researchers did transfers ambient heat into light. Unlike ambient heat, which is nearly impossible to exploit to do work without a heat differential, light is a form of energy that can be converted into other forms to perform work.

 

Energy is still conserved, but the device puts out more energy in the form of light than the electric current that powered it. Ambient heat, without any heat differential, would generally be considered a form of "free energy" if it could be harnessed to perform useful work.

It is not merely a heat pump. Heat pumps simply concentrate heat by transfering heat from one place to another.

The experiment that the researchers did transfers ambient heat into light. Unlike ambient heat, which is nearly impossible to exploit to do work without a heat differential, light is a form of energy that can be converted into other forms to perform work.

 

Energy is still conserved, but the device puts out more energy in the form of light than the electric current that powered it. Ambient heat, without any heat differential, would generally be considered a form of "free energy" if it could be harnessed to perform useful work.

 

So it is a heat pump that makes light instead of heat. And when the light is absorbed, it's heat again. So, it's a heat pump, but a little more complicated and more awesome.

 

There are systems, already on the market for many years, that use a heat pump to heat houses. For every Joule of electricity used in the pump (compressor), about 3-5 Joules of heat are released into your house.

another article, confirming that ambient heat is transformed into light, resulting in a cooling effect:

 

http://physicsworld.com/cws/article/news/2012/mar/08/led-converts-heat-into-light

 

In principle, it should be possible to use room temperature heat as a free energy source. Only technical barriers exist.

another article, confirming that ambient heat is transformed into light, resulting in a cooling effect:

 

http://physicsworld.com/cws/article/news/2012/mar/08/led-converts-heat-into-light

 

In principle, it should be possible to use room temperature heat as a free energy source. Only technical barriers exist.

That's not what the article says or implies. Ambient heat was not converted — the LED was at 135 ºC. To cool something at ambient temperature you'd have to pipe the photons somewhere, since wherever they are absorbed, they will heat the material up.