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.