[ars]

No, this is just not true.

You can only convert the kinetic heat motion of a single molecule to kinetic energy in your target if your target is colder than the source! And there's your cold sink.

The efficiency is not 100% because the target sends energy back to the source since the target is moving (from heat kinetic energy).

If the target was standing still efficiency would be 100% - but that's the same as saying the target is at absolute zero and we already know that Carnot efficiency is 100% if the sink is at absolute zero, so it makes no difference that you are dealing with a single molecule.

To your second point that this is "heat being directly converted to photons" - that's exactly the definition of blackbody radiation. But the blackbody also absorbs radiation from the environment it is in, so it's not perfectly efficient either.

[pbhjpbhj]

It's simply not a full system analysis, > unity efficiency WRT input electrical energy. There's just a corresponding draw of energy from the environment that is also producing photons.

>"You can only convert the kinetic heat motion of a single molecule to kinetic energy in your target if your target is colder than the source! And there's your cold sink." //

This is counter logical. You're saying that a small fast moving body can't impart energy to a large slow moving body. Can you explain further how this works at the single molecule level?

[ars]

> There's just a corresponding draw of energy from the environment that is also producing photons.

It is only possible to do that if the photons are sent somewhere that is colder than the device.

> You're saying that a small fast moving body can't impart energy to a large slow moving body.

No, I'm saying it can't impart all of its energy, and the more energy the other body has the less energy it can impart. i.e. it's exactly Carnot efficiency.

Perhaps what you don't realize is that Carnot efficiency doesn't represent lost energy. It represents heat energy than can not be converted to another form, and remains in the source.

[pbhjpbhj]

>It is only possible to do that if the photons are sent somewhere that is colder than the device. //

Where are you deriving this from. What force prevents me shining a light towards a hot object.