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Power Science Technology

Lasers Etch a 'Perfect' Solar Energy Absorber (phys.org) 82

Posted by BeauHD from the practice-makes-perfect dept.
fahrbot-bot shares a report from Phys.Org: The University of Rochester research lab that recently used lasers to create unsinkable metallic structures has now demonstrated how the same technology could be used to create highly efficient solar power generators. In a paper published in Light: Science & Applications, the lab of Chunlei Guo, professor of optics also affiliated with Physics and the Material Sciences Program, describes using powerful femto-second laser pulses to etch metal surfaces with nanoscale structures that selectively absorb light only at the solar wavelengths, but not elsewhere.

A regular metal surface is shiny and highly reflective. Years ago, the Guo lab developed a black metal technology that turned shiny metals pitch black. "But to make a perfect solar absorber," Guo says, "We need more than a black metal and the result is this selective absorber." This surface not only enhances the energy absorption from sunlight, but also reduces heat dissipation at other wavelengths, in effect, "making a perfect metallic solar absorber for the first time," Guo says. "We also demonstrate solar energy harnessing with a thermal electric generator device." "This will be useful for any thermal solar energy absorber or harvesting device," particularly in places with abundant sunlight, he adds.
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Lasers Etch a 'Perfect' Solar Energy Absorber More

Lasers Etch a 'Perfect' Solar Energy Absorber

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  • "selectively absorb light only at the solar wavelengths"

    Considering the sun emits pretty much across the entire goddamned EM spectrum, did they mean to say VISIBLE wavelengths instead of solar wavelengths? Perhaps they meant to say "selectively absorb wavelengths of light within the solar constant" (which would include all solar radiation, not just the visible wavelengths.)

    • Re: Only Solar Wavelengths (Score:4, Interesting)

      by yeshuawatso ( 1774190 ) on Wednesday February 05, 2020 @03:42AM (#59692230) Journal

      Yeah, that part was a little confusing right along the lines that this is thermal energy, not photovoltaic which is what I immediately presumed based on the headlines. My second thought was how this absorbs "solar" energy but ignore EMR considering you can't have one without the other? Hell, if they can tune these nanoscale structures this well, then we might have a way to create more accurate, and fewer parts, fixed RF systems.

    • The paper describes it a bit more:

      [A]n ideal solar light absorber has nearly 100% absorbance within the solar spectrum [300–2500nm] and negligible thermal emittance within the blackbody radiation spectral range at mid-to-high temperatures (100–500C)

      The radiation from a blackbody at 100–500C peaks at around 8000–4000nm (in the infrared). So the idea is to maximize the energy absorbed from sunlight, while also minimizing losses due to thermal radiation.

      Presumably your solar absorber will also be insulated with a vacuum or something, to cut down on convection / conduction losses.

      • So orbital solar arrays as close as mercury, in theory, could divert massive amounts of solar radiation into power without melting, assuming the rest of the structure can hold up to neutron bombardment over time from the solar winds. Obviously it would have to be in equatorial regions to avoid the fast solar winds, but I would think, given the inverse square law, that there could still be a nuclide risk even in the slow solar wind belt. The higher atomic number elements tend to have more neutron-proton, and

        • So orbital solar arrays as close as mercury, in theory, could divert massive amounts of solar radiation into power without melting, assuming the rest of the structure can hold up to neutron bombardment over time from the solar winds.

          No. This stuff gets extremely hot, and radiates little heat. It would melt quickly.

          This is solar-thermal, not photovoltaic.

  • We didn't get an article about those unsinkable (Score:3, Informative)

    by BAReFO0t ( 6240524 ) on Wednesday February 05, 2020 @04:06AM (#59692256)

    Probably had to be cut due to more important topics like Trump Appleing Bitcoin...

  • If it's cheap enough. That is the real appeal of that particular technology. I don't see how that would work for electrical generation. Solar thermal seems to all be focused on concentrating collector designs.

    Needless to say it does nothing to address solar's real problem, that turning on the lights doesn't turn on the sun.

    • I don't see how that would work for electrical generation. Solar thermal seems to all be focused on concentrating collector designs.

      Theoretically, you'd need less of a concentration and/or a smaller collecting surface to generate the same amount of heat.

      Needless to say it does nothing to address solar's real problem, that turning on the lights doesn't turn on the sun.

      Wow! You must be the first person to have ever realized this problem. It's too bad they haven't developed a variety of storage technologies to deal with this problem. Or that load happens to be highest when the sun is up.

  • This vs. hohlraum (Score:3)

    by DrMrLordX ( 559371 ) on Wednesday February 05, 2020 @09:21AM (#59692708)

    Can anyone explain why a surface etched in this fashion would be better than directing sunlight via a solar concentrator into the aperture of a hohlraum?

    • It's flatter? It's simpler? It uses fewer materials and is (probably) cheaper?

      It sounds like the effect is basically the same, but this is just a big flat surface which is macroscopicly uniform.
  • Sorry, but it's just solar thermal collector and solar thermal has all but completely failed in favor of solar PE which generates much more useful electricity and is easier to install and even easier to maintain since wires are easier than pipes. As far as generating electricity, YEAH RIGHT, there is no way to generate electricity from heat efficiently enough that solar thermal makes sense. You will spend more, maintain more and have to higher more engineers for a solution like that vs solar electric panels

    • Sorry, but it's just solar thermal collector and solar thermal has all but completely failed in favor of solar PE which generates much more useful electricity and is easier to install and even easier to maintain since wires are easier than pipes.

      Perhaps you should learn about this amazing thing called "a shower". Or "a bath". They require heating water.

      Or you could learn about this odd thing called "central heating".

      Even better, you could learn about this thing called "paragraphs".

  • This is how holographic filters are prepared. Basically, the laser etches lines within glass or other transparent substrate, with line widths equal to that of the wavelength intended to pass. Thereafter, only those wavelengths pass easily through the glass.

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