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NREL Analyzes Floating Offshore Wind Technology for Statoil

November 6, 2014

NREL engineers traveled to Oslo, Norway, to meet with Statoil representatives regarding NREL’s analysis of Statoil’s Hywind II offshore floating wind turbine design. Statoil’s Hywind II is a 6-MW turbine on a floating spar-buoy foundation. The design for Statoil’s foundation is based on floating spar technology that has been used successfully by the offshore oil industry since the 1990s. In 2009, Statoil deployed its first offshore wind demonstration project, Hywind I, off the coast of Norway. Hywind I has a 2.3-MW turbine on a floating spar foundation that extends 100 meters beneath the surface. The Hywind II design is an optimized version of Hywind I. It incorporates a shorter, lighter, more compact spar extending 76 meters beneath the surface with a 6-MW turbine. Statoil plans to deploy five of these systems in a demonstration project off the coast of Scotland by 2017. Statoil has also called upon NREL to analyze future applications of this technology in U.S. waters.

NREL is using its FAST software to analyze the loads of both the 6-MW turbine and its floating foundation and to assess the integrity of the structural design combined with its control methodology under environmental conditions of a proposed U.S. deployment site, covering the load cases recommended by IEC standards. This coupled analysis of the system is vital to assess the combined effects of loading from winds, waves, and currents and to examine the resonant frequencies of the system during the front-end and detailed engineering work.

NREL is using its Simulator for Offshore Wind Farm Applications (SOWFA) to study individual turbine response as well as the effect of wakes from wind turbines located upwind.

A concept resource assessment performed by NREL will allow Statoil to concentrate its wind farm development on higher value sites, as the combination of available wind resource, bathymetry constraints, and other constraints limit the regions in which Hywind technologies may be deployed. NREL will help Statoil identify the high-value sites based on available wind resource data, capacity, production and losses, electrical cable layouts, costs, and financing assumptions. Statoil will use this information to build a business case for moving from demonstration projects to commercial deployment in the United States.

—Kelly Yaker