Gusty efforts

In what is a natural progression, offshore oil companies are shifting to offshore wind power. Eying the vast potential for establishing wind farms at sea, companies along Norway's west coast, like Statoil and Statkraft, are making the leap. The two Norwegian companies, together with the energy companies Scottish and Southern Energy and RWE npower, will develop Dogger Bank, by far the largest British wind power project to date.

Troll Power, another Bergen company, currently supplies power to the petroleum industry. Its new company Troll WindPower, together with wind power supplier NorWind, is now gearing up to supply power systems for offshore wind farms. Troll Power has developed a tool to detect risks in the power grid when various energy producers and users are connected to the grid. This new tool will be very valuable to grid operators and energy companies as more and more wind farms go online.

Many others from the oil sector are intrigued by the prospect of applying their offshore expertise to the dynamic field of renewable energy.

The engineers at Sway are confident in their windmill design, which unconventionally places the rotor behind the nacelle. As the floating tower leans some 6-8 degrees away from the wind, this downwind design allows the unit to tilt forward -- keeping the blades aligned with the wind's force to capture its maximal energy.

While offshore wind power resources are abundant, wind turbines are currently unable to provide steady power due to natural fluctuations in wind direction and strength.

But every problem has a solution. Offshore wind power output can be made more consistent by choosing project development locations that take advantage of regional weather patterns and by connecting wind power generators with a shared power line, according to a paper by researchers from the University of Delaware and Stony Brook University published in the April 5 issue of the Proceedings of the National Academy of Sciences.

The researchers analyzed five years of wind observations from 11 monitoring stations along the U.S. East Coast from Florida to Maine. Based on wind speeds at each location, they estimated electrical power output from a hypothetical five-megawatt offshore turbine. After analyzing the patterns of wind energy among the stations along the coast, the team explored the seasonal effects on power output. Analysis shows that when transmission systems will carry power from renewable sources, such as wind, they should be designed to consider large-scale meteorology, including the prevailing movement of high- and low-pressure systems

The researchers found each hypothetical power generation site exhibited the expected ups and downs, but when they simulated a power line connecting them, the overall power output was smoothed so that maximum or minimum output was rare. In the particular five-year period studied, the power output of the simulated grid never completely stopped.

Reducing the severity of wind power fluctuations would allow sufficient time for power suppliers to ramp up or down power production from other energy sources as needed. Solutions that reduce power fluctuations also are important if wind is to displace significant amounts of carbon-emitting energy sources, the researchers said.