h a l f b a k e r yRecalculations place it at 0.4999.
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There are alot more parts of the
scale than light which we can
convert to energy. Radio waves,
infer-red, microwave, etc etc.
So what about a material/device
to convert any frequency to
electrical power? Some people
say there isnt enough EM to make
decent power, but there most
likely is.
My father said that
if there were enough to make
usable energy, it would be frying
us right now. But, light can
make decent energy, and there are
many other frequencies which can
be taken by the body in much
greater quantities and have no
harm come to us.
Questions? Comments?
Popular Science May Cover Story.
http://www.popsci.c...may2001/warped.html
All kinds of spectra, seen, known, and theorized. [reensure, May 19 2001]
Thermodynamics glossary
http://www.engineer.../thermodynamics.htm
Carnot efficiency and other principles of thermodynamics briefly defined. [bristolz, Oct 04 2004, last modified Mar 03 2006]
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Nope, the vast majority of the energy around us is in the visible spectrum or nearby. Why do you think that's what we've evolved to see? |
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I don't think so. The Sun is, by and large, a blackbody radiator with a spectral peak at the frequency we perceive as green. |
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Given that electromagnetic radiation occurs in a continuum of frequencies (and ignoring for a moment [egnor]'s perfectly valid point that the particular range that we see [and use to generate electricity {in photo-voltaic cells}] is the most predominant), all (!) you need is a PV cell which responds preferentially to a frequency outside the visible spectrum. |
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I don't disagree with anything anybody's annotations so far, but I'd note that at the energetic end of the EM spectrum any X-rays and gamma radiation arriving from space are blocked by the atmosphere and therefore unavailable; UV light is available (do existing photovoltaics use UV?); infrared radiation is used by things like solar water heaters and conspicuously baked as an energy source; and naturally-occurring microwave and radio frequencies are very diffuse and carry little energy. I think that about wraps up the EM spectrum. |
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If our present solar photovoltaic devices would profit full visible spectrum the world could solve their energy problems very fast. |
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As someone pointed out the visible spectrum is more than 90% of all energy irradiance on the wolrd's surface, we have developed our eyes to perceive this spectrum, not surprisingly. |
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I repeat, the problem is finding a device that takes a good steak of the visible spectrum, and not just a narrow gap of it. There are basically three ways: stacked multiband photovoltaics, thermophotovoltaics and thermal systems. |
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Thermal systems are limited by the Carnot efficiency. |
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churned via random button. sleepless, sorry. |
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weird how the random button hits neglected ideas... |
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Better if, when you churned neglected ideas, you added a salient comment ;-) |
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I'd tend to think that while solar power is good, it would be better if it could convert the light it does take in at an efficiency better than 30%... no matter whether that was a narrow band, or a wide chunk of the EM spectrum. |
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Today, to get a solar panel to do that requires it to have three layers, and it ends up costing more than the electricity it produces is worth... OK for space where there's no other power source, but not competitive here where we can just burn coal and destroy our environment for cheaper. |
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