TidEl Harnesses Lunar Energy?
by Jacob Gordon, Nashville, TN on 08.31.05
In a previous post we saw plans to propel freight ships with the help of giant paraglider-like sails. Here, instead of going up to catch high-speed air currents, TidEl technology goes down to the bottom of the ocean to harness strong water currents. Another winner of an Echo-Tech award at this year’s World Expo, TidEl technology, developed by SMD Hydrovision out of the UK, operates much like a wind turbine but instead uses the twice daily tidal movement of ocean water to generate power. Moored on chains to a point on the sea floor, the twin turbines are free to move and change direction as the tide goes in and out. Currently the company has only gotten as far as a 1:10 model in a testing tank. On the real thing, each turbine would be 15 meters across with a 500 kW combined output…
Unlike wave power, these devices would be as many as 30 meters below the surface, safe from storms, seagulls, what have you. While being way down there may pose a unique set of challenges, the company claims TidEl can be remotely triggered to rise to the surface for routine maintenance. Technologies like TidEl may be a welcome alternative to wind farms that take up large areas on land or at sea, and also may satisfy those who find wind farms unsightly. Underwater energy farms may also offer an alternative to massive hydroelectric dams that prove so ecologically and socially disruptive. As of yet, nothing has been said of the potential impacts on aquatic ecosystems from tidal stream turbines (although let your imagination run for a second and you might be on to something). Proposed turbine farms would range from 30 to 100 units, providing a max. output of 100 megawatts per farm. Energy would be transmitted to land along underwater cable. The underwater vehicles that lay this cable (again, let your imagination run) are also available from SMD Hydrovision.
Lastly, since the motion of the ocean is largely a result of the gravitational force of the moon as it literally bulges the sea from one side of the earth to the other, couldn’t we say this is lunar energy ? Solar is so clearly over.
Are these, uh, dolphin safe?
How often would these units need to be maintenanced? Where's talking a lot of buildup and corrosive damange aren't we? Is the cost and efficiency to maintain these units beneficial in the long run?
Also, not just dolphins, but whale safe? Shark safe? Where, specifically, are we considering installing these units? Will they affect the migratory patterns of any animals in the area?
Other than all that, sounds great!
"Are they xx safe?" ... it seems all of these technologies (see also Verdant Power, the wave dragon, and there's at least one other big pylon-mounted one,) are kind of in the "only one way to find out" stage...especially with Verdant Power, they've got a sort of provisional environmental permit that involves lots and lots of monitoring how wlidlife integrates with these types of technologies....no one knows yet, but hopefully they'll be less reactive about this than the wind industry has been.
Marine Current Turbines! That was the one I couldn't think of.
another type of tidal power turbine can be found at:
http://www.bluenergy.com
Regarding marine animal life this turbine manufacturer says:
"The array of slow moving turbines allows water and fish to flow freely and safely through the structure. Larger marine mammals will be prevented from contact with the rotary foils by a protective fence, and further protected by a backup auto-breaking system controlled by sonar sensors."
Neat idea, but it seems somewhat 'unfair' to place them underwater where they won't be bugging us with their unsightliness and noise. Out of sight, out of mind so to speak. If we are hungry for power, I'd rather the methods of generating it to be in my face, for a reminder that every time I flip a lightbulb, there's a corresponding cost (besides just monetary). Imagine if all our reactors, power plants and corresponding pollution was hidden from sight? This just hides the mess.
On the flip side, it is green (until they put up so many it starts affecting local current patterns, whale calls, etc). I think the maintenance on these would be nuts (that fence to protect animals would get barnacle encrusted, cutting into available power...and the auto-breaking by sonar sensors...the parent company will be fuming everytime one of these shuts down because a dolphin got interested).
Heh, as a plus side, as the water levels rise, we'll have more room for these ;) (j/king)
Just my 2 cents,
Matt
TidEl can be installed below light depth, then no problem with barnacles etc. Maintenance is by extending anchor chain so that the machine floats to the surface for repair or even exchange. The machine is not very big. The company envisages a farm of them. Corrosion should be minimal at the envisaged depth which has to be as low as easible at the selected site.