Tidal Energy

Harnessing Tidal Energy: Tidal Stream Systems

When there are obstructions such as continents, inlets, islands, etc., water piles up against the obstruction and flows rapidly past when and wherever it can. This makes tidal currents. These currents can be used to drive underwater turbines, which is another method for harnessing tidal energy.

Underwater turbines are anchored to the sea floor so the moving water from tidal currents can rotate the blades. Just like wind turbines, the rotating motion of the blades generates electricity which can be sent to the utility grid.	Lots of underwater turbine designs are being prototyped. The Evopod began testing in June 2008. It uses a tether rather than a rigid anchor. The turbine is mounted on a floating, semi-submerged structure. This design is easier to maintain and can capture the fastest tidal currents which are just below the surface.	The world’s first commercial tidal stream generator is SeaGen which was installed in Northern Ireland’s Strangford Lough in April 2008 and started generating electricity for the grid in July 2008. SeaGen is an axial turbine, a tall tower bolted to the seabed. The blades can capture the motion of tides going in as well as out. There are discussions to build entire tidal farms using turbines like these.