Random thought of the day

There exist heat pumps that can heat our homes with greater than 100% efficiency compared to converting the electrical/mechanical energy directly into heat.

Could there exist a means to make a “light pump” and convert large quantities of infrared light (thermal energy) into smaller quantities of visible light as a means of artificial lighting at something greater than the abysmal  efficiencies of our existing light sources?

15 thoughts on “Random thought of the day

  1. I have to imagine that there is a portion of a solar cell that deals with light outside the visible spectrum.

    If this is a climate question then there is already a similar, just more organic solution:
    http://www-formal.stanford.edu/jmc/progress/iron/iron.html

    Of course since the end-goal of the Global Climate change is NOT the environment but a vehicle for National Socialism, nobody is very interested in this altruistic solution.

  2. Isn’t the operative fiddly bit of your “light pump” a laser? Coherent Light is the answer. Figure out how to transport it in a tube/fiber, diffuse it, aim it, etc, and you have the whole apparatus, which will work an ANY frequency of the light spectrum.

  3. I was thinking of using the light pump as an efficient means of lighting buildings and streets. I don’t think a laser (or night vision equipment which I also considered) is an efficient means of doing the desired task even though they do “pump” light.

  4. “There exist heat pumps that can heat our homes with greater than 100% efficiency …”

    Really? Please explain how this doesn’t violate the 2nd Law of Thermodynamics. Or am I missing something?
    Oh well, entropy isn’t what it used to be.

  5. Fluorescence could produce visible light (an electron absorbing two IR photons and emitting a photon at a shorter wavelength). Probably horribly inefficiently.

  6. A heat pump is basically a refrigerator running in reverse, which is basically limited to Carnot efficiency (ideal case). In the real world it might achieve ~33% efficiency, at best. But I think what he’s saying is that the other way of heating a house (basically burning something, creating a convection cycle) is only ~15% efficient. Voila! the heat pump is >100% more efficient.

  7. I worked for a semiconductor equipment manufacturer who has a product that uses microwaves to power a gas-filled bulb, resulting in very high output of selected wavelengths of light. The light is used to “cure” some types of photoresist on silicon wafers.

    The light could be tuned, by varying the chemical composition of the gas in the bulb, to provide a natural looking light. Then this one bulb, powered by a relatively simple microwave source, could be connected to a glass fiber light cable that dropped light wherever it was wanted, throughout a whole building. A whole building was lit by one bulb.

    LEDs are where the smart money is going, however. Is there anything CREE has done that hasn’t been a smash hit?

  8. @Mad Rocket Scientist, Yes! Without the conversion to electricity of course. That is awesome!

    @Sennin, If you take your ordinary electric baseboard heater (or your electric toaster) it converts 100% of the electrical energy to heat. It is therefore 100$ efficient. But if you use that same electricity to run a heat pump you get out more heat than if you used that same electricity in the baseboard heater. Hence, one can defend the claim it is greater than 100% efficient.

    The laws of thermodynamics are not violated because the heat pump made some other object (usually the outside air) colder in the process of making the interior of your building warmer.

  9. Short answer – Yes, but it’s useless as a means of generating useful amounts of visible light.

    Long answer – The amount of infrared energy coming off the human body at any point in time would be barely enough to light up a single christmas tree bulb even if converted at 100% efficiency. The amount of heat needed to generate enough heat infrared to light up a house would be absurd.

  10. Electronics suppliers sell these chemically treated sheets for people in electronics repair, used to detect the infrared emissions from the LEDs in TV remote controls. You aim the remote at the sheet and if the LED is working, the sheet glows in visible light. Visible florescence from IR input.

    This one is said to be responsive to wavelengths of 700nm to 1500nm (a little over one “octave”);
    http://www.ersweb.com/Infratector.htm

    Don’t know if that’s barking up the right tree or not, but it’s interesting.

    As said above though, LED home lighting is amazingly efficient, such that it would represent a trivial fraction of the current home’s power usage.

  11. Publius – OK. That makes more sense. Thanks …

    Joe – Yep. You’re right (except for entropy :)) Sorry, I couldn’t resist.

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