A new tidal generator design

What happens if you run an electric motor backwards? In short, it stops being a motor and becomes a generator. Following this principle, researchers at the University of Southampton have built a new kind of tidal stream generator which could substantially reduce the cost of electricity generated from tidal power within five years.

What happens if you run an electric motor backwards? In short, it stops being a motor and becomes a generator. Following this principle, researchers at the University of Southampton have built a new kind of tidal stream generator. Their simple and elegant design has fewer parts than most current tidal stream generators. So this could substantially reduce the cost of electricity generated from tidal power. So far, the team has only built a prototype, but expects that this generator will be commercially available within five years. But read more...

This press release from the Engineering and Physical Sciences Research Council (EPRSC) describes the work of two researchers at the University of Southampton, Dr Stephen Turnock and Dr Suleiman Abu Sharkh, and the simplicity of the design of their tidal generator.

"This is a compact design that does away with many of the moving parts found in current marine turbines. It's a new take on tidal energy generation," says Turnock.

Below is a computer generated image of this compact electric generator (Credit: Turnock and Abu Sharkh, via EPRSC).

A computer generated image of this new tidal generator

And here is a picture of the prototype that was tested (Credit: Turnock and Abu Sharkh, via EPRSC).

The prototype of this new tidal generator

Now what is so unique about this new tidal generator?

Most current tidal stream generators are essentially wind turbines turned upside down and made to work underwater. They often include complex gearboxes and move the entire assembly to face the flow of the water. For example, they turn a half a circle as the tidal current reverses direction. Gears and moving parts require expensive maintenance, especially when they are used underwater. This pushes up the cost of running the turbines, a cost that is passed on to the consumers of the generated electricity.
The Southampton design does not need to turn around because the design of its turbine blades means that they turn equally well, regardless of which way the water flows past them. The blades are also placed in a specially shaped housing that helps channel the water smoothly through the turbine.

But so far, the prototype is quite small -- just twenty-five centimeters across -- and the researchers want "to design a larger model with improved propeller blades that will further increase the efficiency of generating electricity."

If all goes well, such generators could become available within five years.

Sources: Engineering and Physical Sciences Research Council news release, via EurekAlert!, June 13, 2006; and various web sites

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