tidal power


The innocence and unbridled optimism (and pessimism)of youth is inspiring. I was ranting to a teenage friend about sensible ways of making power instead of oil when he asked me to just complete my thoughts and make a plan. You may already know I have an issue with the masses of waste plastic. Mix that with the need for alternative power… you can see where I’m headed. Clean Power generating devices made with that old plastic. Dams on rivers are efficient but can be ecologically imposing. Windmills are pretty great but they have unpredictable performance and they take up huge amounts of landscape far away from the power loads. What other options are there? I have an Idea, I have been thinking about this for many years but it is time to bring it to some form of a working model to prove or disprove it’s credibility. I’d love to get constructive criticism and or offer these designs to be used.

harmony & spinnerflat and angled designsshoe polisherweathervane

I’m not the first one to conceive of the idea of harnessing tidal power, tidal barrages have been used for centuries but they too are problematic to estuarine life. I propose a slow moving impeller made of recycled plastic, submerged in areas of predictable tidal currents. Two key elements are crucial. It has to elegantly fit with it’s environment, and it has to be simple. The idea is a machine that lives in harmony with it’s surroundings. Not just visually but as part of the ecosystem as well. Norway and the UK have a similar idea for undersea generators. Also interesting is the wave hub which can utilize the brilliantly designed waveswing.The waveswing only requires areas of good wave exposure and I could see it potentially using recycled plastic. These ideas are great innovations but most are fairly expensive to make. One simple solution I propose is that a mechanical form of power like a shaft should come out of the water to generate the electricity on land, away from corrosive salt and avoiding expensive technology required in waterproofing as well as maintenence. The materials are plastic from recycling, concrete ( possibly even based on the type the romans had that used salt water to cure) and some easily replaced bearing surfaces. The other problem the Norwegian style generators face is fishing nets and other entanglement. This is because the design is not streamlined nor simple enough. Maybe it is just an even slower propeller design with a smoother profile, encircled more like an impeller. The concept of tidal power is fascinating and promising if the designs we use are smart enough to be low impact and beneficial across the board.

some rough visualizations of my ideas:
kinetic mantasupright manta watermillharmony 4 caged

outside links to underwater power generating devices
wave dragon
pelamis video
The Ocean Renewable Energy Coalition

3 Comments so far

  1. DouglasBarnett on June 27th, 2007

    Gorgeous web site.
    Note the – life costs of recycled polypropylene in this carpet example:
    The software does not consider the added human value of a new, clean carpet more often, rather than an old long lived carpet.

    When I built urethane Piranha (for the movie Piranha) and fishing line guides to tow the things underwater in the coliseum Olympic swim stadium (three weeks in full scuba in the pool!)they did everything , twisted, porpoised, fishtailed and snapped back… reproducing nature is a tough nut to crack.
    An “Archimedes screw” works between two “mediums”, air and water.


    Won’t work well submerged. An “airfoil” only works well in a compressible medium.
    Fish “swim” without compressing water, but as a tractor.
    Boat propellers are not wings like aircraft props, i don’t think.
    I think you might instead store a compressible (air) as the water rushes back and forth over your plastic device, and close-circuit this to a pnuematic generator above. The torque stiffness required over a long (50, 150 ft)shaft is almost impossible unless “wind-up” could be useful. Perhaps a tension cable(plastic) maintaining position and transmitting rotational or linear cycling strokes to the surface.

  2. testwiggle on January 25th, 2009

    Hi there.

    Thought I’d throw in my 2 cents…

    I’m not keen on tidal barrages (due to it completely changing the natural water system), or to some extent the “submerged wind turbine” (due to the exposed moving blades) approach as they are very high impact in terms of ecology and even the geography of an area.

    The devices I’ve most considered for tidal power are based on anchored buoys.
    Basically you have a buoyant device which moves up and down [relative to the anchor] with the tide.
    The simplest is a tower founded on the sea floor, with a ring-shaped buoy around it. The buoy could itself contain 2 alternators with gears attached, that would be driven by a static rack on the sides of the tower, with cabling feeding back into the tower, along the sea bed, to the shore.
    As the tide rises, so does the buoy, driving the alternators in one direction, and as it falls the alternators are reversed.

    Other versions could use tethers as the anchor in place of the tower, allowing some energy to be generated from some lateral movement too (e.g. currents).

    Varying the torque (and output wattage) with electromagnetic resistance would allow both slow (high torque, high output – e.g. tide) and fast (low toque, low output – e.g. currents and waves) to be used to generate power.


  3. testwiggle on January 25th, 2009

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