Soon, A Turbine That Can Fly Like A Kite In The Water

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Companies and governments are counting on underwater turbines hat turn the tides into a source of energy from deep beneath the sea. Researchers are developing a dual-rotor turbine connected to the seabed by a cable that rides the tide like a kite on a windy day.

According to a report in Scientific American, Researchers goal at University of Strathclyde's Energy Systems Research Unit (ESRU) in Scotland is to create a device that literally goes with the flow rather than resting on the sea bottom like an underwater windmill.

The kite and cable model is designed to facilitate placing tidal turbines in deep water, where the stronger current has the potential for providing reater power but also makes it extremely difficult to plant a turbine in the seabed.

"The problem with regular turbines is the bigger they get, the harder they work, and the more likely the force of the water is to damage the turbine," said Andrew Grant, an ESRU mechanical engineer. "Our turbine can fly like a kite in the water," he added.

Instead of planting the base of a turbine in the seabed, researchers need only plant an anchor for the tether.

Another key difference in ESRU's design is that the turbine has two rotors attached-one in front of the other that turn in opposite directions on a single axis. The rotors' blades are made of either solid aluminum alloy or glass-reinforced plastic, depending on their sizes.

By having the rotors turn in opposite directions, Grant and his team are trying to cut down on reactive torque (which pushes the turbine in the opposite direction) so that the unit can be attached to a relatively simple mooring system even in very deep water.

But, Grant acknowledges that tidal-derived power has a long way to go before it can be used as a mainstream source of energy. He expects it will be a decade or more before ESRU's turbines are ready to be used in earnest in the sea