World's first floating wind turbine opens in Norway

Yahoo News 8 Sep 09;

OSLO (AFP) – The world's first floating full-scale offshore wind turbine has been inaugurated in the North Sea off the coast of Norway, Norwegian energy giant StatoilHydro said Tuesday.

The turbine known as Hywind, which measures 65 metres (213 feet) tall and weighs 5,300 tonnes, lies some 10 kilometres (seven miles) off the island of Karmoey near the Scandinavian country's southwestern coastline, the company said.

It rests upon a floating stand that is anchored to the seabed by three cables. Water and rocks are placed inside the stand to provide balast.

StatoilHydro plans to test Hywind over the next two years before it looks to set up any more floating wind turbines with international partners.

StatoilHydro sees Japan, South Korea, California, the east coast of the United States and Spain as some of the potential markets to where this technology could be exported.

Hywind can be used in waters from 120 metres to 700 metres deep allowing it to be placed much further away from the shore than static wind turbines already in operation.

StatoilHydro's Anne Stroemmen Lycke told AFP that the floating turbine has "great advantages."

"It is not so easily seen from the coast, it can be placed in areas not used by others," she said.

"We could use such wind turbines in countries where coastal waters are very deep or where there is little space left for land-based turbines," Stroemmen Lycke added.

A total of 400 million kroner (46 million euros, 66 million dollars) has been invested in the 2.3-megawatt floating turbine, making it a far more expensive option than its fixed counterpart.

"Our goal is to bring down the price to the level of fixed wind turbines that are currently installed in waters some 60 metres deep," Stroemmen Lycke said.

France's Technip and Germany's Siemens both worked with the Norwegian energy giant on the Hywind project.

It is set to start producing electricity in the next few weeks, StatoilHydro said.

Floating challenge for offshore wind turbine
Jorn Madslien, BBC News 8 Sep 09;

Heading offshore in the Rygercruise catamaran, it is a journey into uncharted territory.

Not in terms of sea charts - the Norwegian energy giant StatoilHydro knows these waters well, having spent the past 30 years drilling for oil and gas here - but in terms of technology.

Statoil has constructed the world's first full-scale floating wind turbine a couple of hours by catamaran from the oil town Stavanger, in the hope that one day vast wind farms could be constructed far offshore in water depths of up to 700m.

Standing firm as the catamaran rolls in the waves, Sjur Bratland is optimistic with regards to the technology's potential.

Yet, having spent the past two years listening to a whispering crowd of nay-sayers, he wants proof. He wants to see for himself that the turbine can cope with winter storms that whip the North Sea into a froth and winds that rip roofs off houses.

And he wants to be sure that the supply industries can deliver the right turbines, supply ships and so on.

Fortunately, Mr Bratland is in charge of the Hywind project, and he has been given some 400m Norwegian kroner ($66m; 35m) to play with by Statoil, with the government injecting a further 59m kroner.

Trouble shooting

As the turbine slowly emerges through the mist, the first impression is how stable it is.

As the catamaran moves closer, the turbine stands as firm as if it was pinned to the seabed, the way conventional offshore turbines are, its 65m tubular carbon steel tower and slowly rotating 80m diameter blades, together stretching 100m above the sea.

The most interesting aspects of the turbine can be found in the depths of the sea, where a 100m long steel cylinder weighing 3,000 tonnes thanks to its ballast of water and rocks is anchored to the sea-bed with mooring lines that can hold the structure at depths of up to 700m.

So-called slack anchors are used, allowing the structure to move with the seas. In fact, in spite of its apparent sturdiness, the 138 tonne turbine is constantly moving.

Everything below the water line is "known technology from the oil and gas industry", where StatoilHydro has 30 years of experience from its extensive offshore operations around the world, Mr Bratland explains.

"Actually, the really tricky thing is to apply this technology in a completely new setting in a new industry," he says. "That has been a challenge."

Deap seas

The Hywind turbine will be tested over a two-year period, at the end of which Mr Bratland hopes to have found proof that offshore wind farms can be built, and that they are economically viable - perhaps even competitive with conventional offshore wind.

Turbines pinned to the sea-bed are relatively cheap in water depths of up to 25m, when the basic monopole foundation can be used. At greater depths of up to 50m, the tubular turbine towers will need gravity bases and stronger steel structures that push the price up.

Statoil's floating turbine requires the waters to be at least 120m deep, though beyond that the sea is the limit - literally.

"But first, we'll need to look for smarter solutions that make it commercially viable," says Mr Bratland.

Better and cheaper turbines

Above sea level, the offshore structure has been bolted together with a conventional offshore turbine of the sort used for near-shore wind farms that are bolted to the sea-bed.

Ease of entry for maintenance is a seemingly trivial yet major headache for Mr Bratland.

Though the seas are relatively calm, the waves are nevertheless too large for a safe mooring against the base of the structure to enable the BBC team to climb the 17m steel ladders up to the service deck.

At a more fundamental level, turbine technology must be developed specifically for far offshore conditions, he insists.

On land, turbines are getting taller all the time to accommodate ever larger blades, explains Mr Bratland.

For the purposes of floating wind farms, such turbines are not light enough, they are too tall and the rotor blades are too small, according to Mr Bratland's early assessments, made even before the 2.3 megawatt turbine has started delivering electricity through the sea-bed cable that connects it to the Norwegian national grid.

He wants turbine manufacturers to produce lower turbines, to take advantage of winds blowing strongly and steadily close to the surface of the sea. Closer to land, the wind lifts to enter the beaches and climb over the cliffs.

Lower turbines should, together with clever design and material selection, help reduce the turbines' weight, and thus their need for ballast, which in turn should reduce sub-sea costs.

At the same time, Mr Bratland wants the power output of each turbine to be raised to perhaps 6MW, and he wants it all to be cheaper than it is today.

This could be possible as there is tremendous potential for economies of scale, both in terms of mass production, which reduces the cost of each turbine, and in terms of the construction and management of vast wind farms offshore where there are few limits on available acreages.

Moreover, onshore production of floating turbines that are then towed offshore to be anchored in place should prove cheaper than the weather-restricted and costly off-shore construction of sea-bed turbines.

Grid cables transporting the power to shore are neither expensive - in the greater scheme of things - nor technologically complicated to roll out, so this is a minor part of the project, according to Mr Bratland.

"Still, we have some way to go," says Mr Bratland.

"Today's solutions are too costly as the margins are so much slimmer in this area than in the oil and gas industry."