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[w-d] Marine Turbines

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  • Gendun@aol.com
    Hi John, saw yr posting & website - sounds like alot of potential - While one of the main reasons that people like us are so enthused about renewable energies
    Message 1 of 2 , Jun 26, 1999
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      Hi John, saw yr posting & website - sounds like alot of potential -

      While one of the main reasons that people like us are so enthused about
      renewable energies is because we want to see a move away from environmentally
      destructive technologies such as nuclear & fossil fuels, it is important to
      be sensitive that even wind & solar can have environmental impacts. Solar
      cell production can generate toxic byproducts in the manufacturing process &
      wind turbines can kill birds ('cause avian fatalaties' in PC-speak! ;).

      So my question to you is, in the case of marine turbines, which of course I
      think are going to play an important part in a saner energy future... How can
      we make sure that we are not making fish meal by chopping up our beloved
      underwater cousins the fish people ? Or to put it another way, how can the
      deployment of marine turbines be done in such a way as to minimize any
      negative impact on the community of marine life ? There are probably lessons
      to be learned from the experiences with wind turbines in California &
      elsewhere, where siting decisions have been shown to be critical in reducing
      the impact of avian fatalities.

      Thank you for your consideration & best wishes for your success with this
      promising technology.

      rgds/Randy Scovil

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    • John Armstrong
      Randy Thanks for your reply on the subject of marine current turbines, which seems to have raised a lot of interest. You ask about the potential negative
      Message 2 of 2 , Jun 26, 1999
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        Randy

        Thanks for your reply on the subject of marine current turbines, which seems
        to have raised a lot of interest.

        You ask about the potential negative environmental effects of this
        techology, especially with regard to fish kills.

        While I am no expert - and really no-one is since there is practically no
        experience - it seems to me that fish are well used to avoiding things that
        slice through the water. The tip speeds of marine turbine rotors through the
        water are going to be limited to probably 10 - 15 m/s to avoid cavitation
        losses, and this is of the same order as hydrofoil legs and planes, and
        possibly the faster ship hulls (yacht keels? - does anybody know?). The tip
        speeds of ship's propellors are of course much faster, but then fish will
        avoid an on-coming ship. Hydro and barrage turbine rotors are also faster
        but are filter-protected. These speeds (10 - 15 m/s) are a quarter those of
        wind turbine blade tips, where bird strikes are really quite limited, except
        in the case of windfarms sited in the migration paths of large birds. So I
        would not think there would be a marine life threat.

        Pollution risks are mainly from lubrication loss, for instance from the
        gearbox. These risks should be small when you think about the billions of
        tons of petro-chemicals carried around each year on the oceans. Otherwise,
        these offshore installations are usually beneficial to marine life, as the
        anchorages afford protection and something to attach to (usually not to the
        advantage of the installation).

        Other forms of impact would be on fishing, shipping and recreation. I would
        think these would tend to avoid areas of high tidal flow, but if not, they
        would probably have to be excluded. All-in-all, I would think exclusion
        zones would be the biggest impact of this form of renewable energy.

        I would welcome more debate on this subject, although the subject is perhaps
        at the edges of the wind-diesel network. Does anyone know of a more
        appropriate forum, or links to suitable sites?

        Regards

        John Armstrong

        J A Consult Tel/Fax: 0181 994 2645
        76 Dukes Avenue Mobile: 0831 398492
        London W4 2AF Home: 0181 994 0685
        www.jac.ndirect.co.uk johnarmstrong@...




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