Turbines go out-of-sight

Bendigo Advertiser
Wednesday 27/6/2007 Page: 25

THE world's first floating wind turbine could be generating electricity in the North Sea in 2009 under a research pact between Norwegian energy group Norsk Hydro and German engineering firm Siemens. Floating wind turbines would represent a technological breakthrough for offshore power generation, which has had to rely on shallow sites for turbines installed on the seabed.

"It's attractive to have windmills out at sea. out of sight of land, away from birds' migration routes," said Alexandra Bech Gjoerv, head of Hydro's New Energy division at a signing ceremony to develop floating wind turbine technology. "We want to build the world's first offshore floating windmill," Bech Gjoerv said. "We want to produce a lot of energy, out of sight." Under the plan, Hydro will combine its knowledge of floating installations, such as North Sea loading buoys for oil tankers, with Siemens' expertise in building turbines, both on land and standing in shallow waters offshore.

Floating wind turbines are more costly than on land, but could supply power both to offshore oil or gas platforms or to coastal cities, cutting emissions of greenhouse gases from fossil fuels and defusing objections that turbines are eyesores. Hydro said a prototype, costing 200 million crowns ($A39.7 million), could be in place in the North Sea in 2009 assuming the firm secured funding this year.

The timetable is two years later than hoped when Hydro unveiled a floating design in 2005. If tests of the five megawatt wind turbine are successful, a small offshore wind park could be built in 2013-14. A Siemens unit built the first offshore wind park in 1991, with turbines standing on the seabed off Copenhagen.

"Windmills standing in waters deeper than about 30 metres become prohibitively expensive," said Henrik Stiesdal, chief technology officer of Siemens' wind energy unit. "Hydro's is the most elegant and simple solution we have seen." Hydro's design is an upright steel tube with a concrete base about 200 m long with 80 m jutting above the water and three blades 60 m long.

The wind turbine is tied to the seabed by three cables to keep it steady in seas where waves can be 30 m high. Hydro reckons it can work in waters 700 m deep. Stiesdal said other models for wind turbines at sea relied on more complex designs, such as giant tripods mounted on the seabed or turbines mounted on floating boat-like structures.