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View Diary: The simple innovation that could make wind power a big player (230 comments)

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  •  different thing entirely (3+ / 0-)
    Recommended by:
    badger, KenBee, raincrow

    survival wind speed is the max wind speed that the turbine can withstand without damage - i.e. hurricane force winds.

    Tip speed is how fast the very tip of the blade is going. For example, a turbine with an 80 m rotor diameter spinning at 20 RPM has a tip speed of 84 m/s (187 MPH). The tip of the blade goes around a 250 m circumference circle in about 3 seconds.

    So, it's 1/4 the speed of sound, not 1/6 the speed of sound.

    Javelin, Jockey details, all posts, discontinue

    by jam on Tue Jan 22, 2013 at 01:38:33 PM PST

    [ Parent ]

    •  Fast enough to hurt if it hit you (3+ / 0-)
      Recommended by:
      Agathena, PrahaPartizan, raincrow

      At a truck stop in Indiana, I saw a single blade about 100 feet long on a wide-load truck. The fat end was 9 feet in diameter and hollow, all composite material, a beautiful and very impressive casting. Out toward the tip there were little,  1 inch high, fins, like guitar picks, embedded in the edge, a whole bunch of them in the outer 30-40 feet.
      I followed up with a friend that is way into wind (working on getting Cape Wind installed) and his explanation was that they were high pitch whistles that didn't carry very far but were audible to birds far enough out that they would avoid the danger zone.
      I can't remember how much RPM I was figuring for at 100 foot radius, but it was a shock to come up to such a high number.
      Even 1/4 mach is really moving and as I said, the intermittency is the real danger, the birds don't see it coming.
      The spiral cone design eschews that problem, it's always visible in the space.
      Please don't get me wrong, I'm all for weaning us off of Petro, all for renewables and the sooner the better. Just the jobs factor alone is worth it, but I also see some problems with current technologies and promise in some that are in the pipeline.
      I guess I mostly have problems with the Big/Distant approach. It concentrates the power, literal and figurative, in the hands of major corporations where small/close can be more equitably distributed.
      Big lossy systems offend my pennypinching soul and the ecological damage of big transmission lines present problems.
      There is no easy answer.
      There are much better answers than we have now.

      If I ran this circus, things would be DIFFERENT!

      by CwV on Tue Jan 22, 2013 at 02:36:15 PM PST

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      •  serrated (sawtooth) trailing edge (0+ / 0-)

        is actually for noise reduction. Here's a paper on it if you are interested:

        Big lossy systems offend my pennypinching soul
        Large wind is much more efficient than small wind and at a much lower cost per watt.

        Javelin, Jockey details, all posts, discontinue

        by jam on Wed Jan 23, 2013 at 05:36:06 AM PST

        [ Parent ]

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