Can a Wired System Achieve 100% Efficiency?

[Yetaphow]

I was discussing solar cells with my friend and we began talking about law of diminishing returns when once a light is lit up, it will send some of the light to the solar cell and energy back into the bulb. When it goes back to the bulb, it won't have as much energy as it did to light the bulb in the first place. As we go on speaking in theory-crafting on possible instances if a solar cell was actually 100% efficient it would still lose energy! He claims this because of the wires. I know some wires do offer resistances which creates heat and therefore you have loss of energy which is loss of efficiency. I told him in any system that has 100% efficiency that there would be no energy lost. He told me I'm missing the point and I told him yes you can lose efficiency through a wire, but this is a system which is the ENTIRE unit. The wires are part of the system. Is there any system that has 100% efficiency involving wires? If so, what type of wires are they? What would the system need?

 

[Vagn]

Normal wires will always lead to some loss through heat, the only alternative would be superconductors which have zero resistance. Problem is we don't have any that function at room temperature, so you would need to use more energy to cool them to the point where they will become superconductors than you would get off of the lightbulb.

 

[russ_watters]

Welcome to PF.

That's not the law of diminishing returns, that's the law of conservation of energy.

The efficiency of the energy transfer through wires can be so high that you don't need to consider it in an efficiency calculation: much better than 99% for short wires of sufficient size. Light bulbs, mirrors to reflect light, and solar cells all have such low efficiency that such a system could only recover a few percent of the energy it used.

 

[Curl]

solar cells have garbage efficiency as explained by the 2nd law

 

[Yetaphow]

Cool.. thanks guys!

 

[sophiecentaur]

solar cells have garbage efficiency as explained by the 2nd law

And so do electric lamps (in this context, at least).

 

[Curl]

And so do electric lamps (in this context, at least).

You mean incandescent lamps? Correct.

 

[sophiecentaur]

Any lamp is inefficient if you want all the energy into end up as light, getting to the PV cells. It won't get round the loop many timed with even the best lamp you can find.

 

[Curl]

It's not about the lamp, its more about the cells. Efficiency is plagued because of the 2nd law.

 

[sophiecentaur]

?
It's about everything.
It's Perpetaul Motion he's suggesting.

 

[Yetaphow]

Thanks again..He still claims law of diminishing returns, "in a closed-loop system." It is easier to blow out a light bulb with him I suppose. The only law of diminishing returns I know that it relates to would be economics specifically when an application yields ineffectiveness.