Powerful waves hole generator

CHARLES ARTHUR

Technology Correspondent

The world's first commercial wave-powered electricity generator has a problem. It cannot stand up to waves. It has already developed two holes in its steel plating, faced with nothing fiercer than a mild summer swell.

The idea behind Osprey was simple. Moored off the Scottish coast, it would convert the energy of the incoming waves into enough electricity to power 2,000 homes.

But the waves had other ideas. They have begun converting the Osprey into 850 tonnes of junk.

The generator cost pounds 3.5m and took six months to build. Three weeks ago it was towed to a site 300 metres off Dounreay in northern Scotland following a triumphant launch from Clydebank.

But tests this week found holes below the waterline in two of its nine ballast tanks, and pieces of zinc attached to the structure to stop it rusting are falling off to the sea-bed.

Investigators from Lloyd's Marine insurance are now checking the full extent of the damage before making any decisions on whether to tow the structure back into dry dock.

"As soon as you get a small hole, the sea acts on it and enlarges it on a daily basis," said Allan Thomson, managing director of Applied Research and Technology (ART), the Inverness-based company which designed and funded Osprey.

"And the forecast is for worse weather. The swell is only about three metres high at the moment." In the winter, a swell of up to 18 metres is feasible.

The unwanted ventilation has confirmed some of the fears of critics of the concept, such as Dr Donald Macdonald at Imperial College in London.

Before Osprey was launched he said: "I admire [ART's] courage, but I fear for them. Once or twice a year it blows a real gale up there, and virtually nothing remains unless it is a granite lighthouse that's been there a while."

This has not yet happened to Osprey, but winter is on the way.

Mr Thomson though has managed to find a silver, or at least zinc-plated, lining in the developments.

"We took the turbines out of the generator in order to calibrate them," he says. "We were a couple of months away from generating power with them anyway."