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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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General: what's the best way to use this small river ?

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    • CommentAuthorTheDoctor
    • CommentTimeAug 13th 2008
     
    i would have dealt with that as a repair, not asked questions, and told the EA to go pleasure themselves elsewhere if they came knocking.
    • CommentAuthorpahuk
    • CommentTimeAug 13th 2008
     
    TheDoctor, 'Under the Radar Approach' I have heard of and if it doesn't fall within the EA's remit I have seen it work.
    In this particular case, they came to us seeing the application for other work with the Local Authority.
    Does anyone know, when the EA need to know, as I have found if you ask, they say yes to everything and you can't do what you want to.
  3.  
    A German firm has adapted the traditional Archimedes screw to generate energy and this has the advantage of letting fish pass through the screw without problems. A number of examples have been installed in Germany and Switzerland with heads in the range 1-5m, and in principle they can use water flows of 0.1-5m3/sec and heads up to 10m, with power capacities from 3 kW to 300 kW.

    They can be designed to be almost invisible, and are in use on some National Trust properties.

    The guy who does these in the UK is the guy behind the restoration of Howsham Mill as a renewable energy centre

    http://www.rht.greenisp.org/HowshamMill.htm

    Click on the presentation button for pictures of the Archimedes screw (on pages 15 and 16)

    and there's a brief article about them here:

    http://www.forumforthefuture.org/greenfutures/articles/tamingofthescrew
    •  
      CommentAuthorfostertom
    • CommentTimeAug 18th 2008 edited
     
    It's OK but I can't see how it would be more efficient that a trad water wheel - please correct if wrong. Provided the buckets don't overflow, a water wheel must capture every bit of the potential energy of the water that reaches it, losing only to shaft friction - hopefully the bottom of the wheel won't be immersed in the catchpit water. Whereas an archimedes screw is bound to lose some water down the trough/tube past the edge of the helical 'blade'.

    Given an upstream extract point from the river, and a downstream discharge point, a water wheel or archimedes screw must waste some or most of the precious available head, because the incoming and outgoing channels must slope. Even if it's piped not channelled, none of that head wasted on just moving the water is available to generate power, because neither wheel nor screw is capable of using over-pressure in the delivery pipe nor suction in the discharge pipe. Both are pure gravity machines, 'seeing' only the head difference between their own highest and lowest point. Whereas a turbine 'sees' the whole head from the top end of the delivery pipe to the bottom end of the discharge pipe, and can also 'see' the velocity/momentum of the water in the pipe.

    The exception to this would be installation beside a waterfall, so the delivery and discharge channels/pipes would be of negligible length and fall.

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