19 votes

These nearly silent wind turbines have owl-inspired ‘feathers’

3 comments

  1. scroll_lock
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    Comment box Scope: information, summary, brief opinion Tone: neutral Opinion: a little Sarcasm/humor: none NIMBYs often complain that wind turbines are loud as an excuse not to build them. Okay....
    Comment box
    • Scope: information, summary, brief opinion
    • Tone: neutral
    • Opinion: a little
    • Sarcasm/humor: none

    NIMBYs often complain that wind turbines are loud as an excuse not to build them. Okay. Here is a possible solution:

    Noise from wind turbines limits where they can be built. But a design that mimics the shape of owl feathers can make wind farms quieter and help renewable energy grow faster.

    Like airplane wings, wind turbine blades are shaped so that air flows faster on one side and slower on the other, creating lift. At the trailing edge of the blade, where the air mixes, there’s noisy turbulence. To help, blades are designed with a serrated edge that helps break up the airflow. But Church, who has also developed other nature-inspired designs for renewable energy, realized that it was possible to go farther.

    Owls use a variety of strategies for silence, but Biome’s design is inspired by the shape of the fringe on the trailing edge of some owl feathers. The FeatherEdge’s shape uses the same principles of physics to cut noise. The engineers customize the design for each specific wind turbine, applying the flexible attachments at key locations to control how the air mixes.

    The design works. The standard serrations on wind turbine blades cut noise by 1.5 to 2 decibels; in early tests, FeatherEdge reduced noise by an additional 3.4 decibels. (It’s possible that the latest installation, on massive turbines, may show even greater reductions when the results are in.)

    A noise reduction of 3.4 + 2 decibels, or even just the reduction of 3.4 decibels to improve turbines that already have serrated designs, is meaningful and probably worthwhile. More so if the large tests mentioned in the article (data TBD) have good results. I'm not sure that is a night-and-day difference, but the article is optimistic:

    With the new design in place, it could be possible for projects near communities to run effectively at night, adding more power to the grid. Because the wind turbines would be so much quieter, it also could be possible to put 30% to 50% more turbines on the same plot of land, he says.

    Noise pollution is one of my pet peeves. There is not a great reason that the places we live and work need to be particularly loud, and it is true that loud noise negatively affects most wild animals. If these designs can be implemented cost-effectively, without reducing wind turbine performance (maybe even improving it), I'd say it's worthwhile.

    11 votes
  2. [2]
    hobblyhoy
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    I'm so confused. I had no idea wind turbines where even loud so I just watched a half dozen videos of active turbines and my conclusion is... They're not loud? Like at all. A single car going...

    I'm so confused. I had no idea wind turbines where even loud so I just watched a half dozen videos of active turbines and my conclusion is... They're not loud? Like at all. A single car going passing by or birds chirping in the background or even the wind itself is much louder. And the sound it does make is actually kind of a pleasant dull white noise. Am I missing something?

    2 votes
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      Comment box Scope: comment response, information, speculation Tone: neutral Opinion: yes Sarcasm/humor: none They’re not particularly loud from a distance—perhaps 45 dB from 300m. They can be...
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      • Scope: comment response, information, speculation
      • Tone: neutral
      • Opinion: yes
      • Sarcasm/humor: none

      They’re not particularly loud from a distance—perhaps 45 dB from 300m. They can be louder up close. Sometimes, the bigger problem I might be infrasound: vibrations that aren’t heard but are felt, and vibrations can cause louder and more irritating sounds. Imagine a piece of metal in your window rattling as a car goes by; you might not hear the car much, but you could hear the metal.

      Anyway, it is usually still pretty minor for humans. That doesn’t stop people from being fussy, especially if turbines are within earshot of homes. It’s mostly an excuse for anti-environmental or generic NIMBY blockage. Technology like this disarms that NIMBY narrative.

      The sound of a car is unusually loud for most animal habitats. In general the only environmental thing to make continuous noise in any natural habitat is running water, which has obvious benefits for all animals. Animals make noises too but that communicates something specific and contributes to an ecosystem (even if it’s a threatening sound). The sound of a wind turbine doesn’t really help an ecosystem? From an ecological perspective, it’s probably best for human infrastructure to be dead-silent if possible.

      6 votes