Wednesday, June 04, 2008

Wind Power Moves into Deep Waters

A floating wind turbine is planned for 10 kilometers off Norway.

By Peter Fairley

The notion of floating wind turbines far offshore may have come a nautical mile closer to reality late last month, with the announcement of a collaboration between Norwegian oil and gas producer StatoilHydro and Germany's Siemens, a major wind-turbine producer. The new partners plan to install what could be the world's first commercial-scale wind turbine located offshore in deep water. StatoilHydro has allocated 400 million NOK ($78 million) to floating a Siemens turbine in more than 200 meters of water--10 times the depth that conventional offshore wind-turbine foundations can handle--atop a conventional oil and gas platform.

By fall of 2009, the project aims to operate a 2.3-megawatt wind turbine in North Sea about 10 kilometers offshore from Karmøy on Norway's southwestern tip. That power output is small compared with the 1,054 megawatts of offshore wind installed in European waters by the end of last year. However, proving deep offshore wind will ensure future growth by expanding the range of wind power, according to Anne Strømmen Lycke, StatoilHydro's vice president for wind power, who says that there are a declining number of sites available onshore and in shallow waters. "Either it's full already, or there's resistance or complicated terrain," says Lycke. "And there are regions without a shallow shelf--California, Japan, Norway--where shallow wind is not possible."

Wind sparring: This power platform designed by Norway’s StatoilHydro uses a spar buoy, a common technology in its offshore oil and gas operations, to place a conventional wind turbine in waters up to 700 meters deep--multiplying the sites available for offshore wind parks. The company expects to be operating a full-scale device off Norway’s North Sea coast by next fall.
Credit: StatoilHydro

At least two other firms are also developing floating wind turbines. Both--Blue H of the Netherlands, and Norway's Sway (itself one-quarter owned by StatoilHydro)--are designing lighter wind turbines to slim down the heft and price tag of the platform required to support them. But Paul Sclavounos, a mechanical engineer at MIT whose lab is designing offshore platforms for wind turbines, has criticized that innovation as misguided at this stage in the technology development, given the complexity and cost of certifying a novel turbine design. In contrast, the project planned by StatoilHydro and Siemens involves mature technologies being implemented by industrial giants.

Indeed, StatoilHydro's plan relies on a combination of well-tested components. A 165-meter-tall spar buoy closely modeled after oil and gas production platforms used in the Gulf of Mexico and elsewhere supports a standard, mass-produced Siemens 2.3-megawatt turbine. Lycke calls the turbine "very robust and very well tested." That will simplify optimization of the floating-turbine concept, she says, "because we know that we're only testing one thing: whether the turbine behaves as predicted in the water."

The prediction from wave pool testing of a scale model is that the turbine should handle life on the waves just fine, thanks to three anchor chains holding the platform stable and the relatively steady winds that prevail far from shore. "Onshore wind turbines are exposed to quite a bit of turbulence and gusts, and that is not the case at sea," says Lycke.

StatoilHydro plans to lower the price of the floating turbine by running it for two years and gathering the data needed to estimate the smallest anchor and buoy required to support a wind turbine. Some additional cost will be defrayed by more consistent winds that keep the turbines spinning more often and thus boosting the megawatt hours of electricity generated by each turbine.

Lycke says that deepwater wind power will be very pricey early on--closer to today's solar power prices--and thus will need government incentives to take off. But she believes that the economics could eventually rival those of conventional wind power. "If we didn't think so," says Lycke, "there would be no point in doing it."