New DOE Lidar Buoys for MABL Measurements in Support of Offshore Wind Energy

There is a critical scarcity of long-term observations above the ocean surface of winds at rotor plane heights for wind turbines in U.S. offshore waters. Most observations are either episodic (e.g. several-week-long scientific field studies) or not publicly available. There have been long-term measurements from European facilities such as the FINO towers in Germany, but those data are not always readily available and are not fully representative of conditions encountered in U.S. waters.

This lack of long-term data is a barrier to the development of offshore wind energy in the U.S. In particular, it has not been established how well assumptions about scaling winds to hub height from buoy observations at the surface actually work. This scaling is typically performed using either a power law or logarithmic profile. In the customary application of these relations, effects of atmospheric thermodynamic stability are not considered. Ongoing research in the atmospheric boundary layer (ABL), including the marine ABL (MABL), shows that stability dramatically affects the shape of the wind profile. Other research indicates that the wind profile shape can deviate substantially from the conventional functional forms depending on the orientation of wind direction relative to ocean swell and whether a low-level jet, which is common in coast areas, is present. Additionally, there is virtually no information about turbulence at hub heights or the behavior of winds and turbulence during extreme weather conditions. Finally, the lack of data has precluded the comprehensive evaluation of the performance of regional weather forecast models used for wind predictions and for developing resource assessment maps for offshore wind energy.

To begin to remedy this lack of information offshore, the U.S. DOE is procuring two WindSentinel buoys from AXYS Technologies, Inc. These buoys will provide data for a variety of research and development activities that are intended to accelerate the development of offshore wind plants in the U.S. These systems will be operated for the U.S. DOE by Pacific Northwest National Laboratory. Following an initial evaluation period, their first deployments will be associated with DOE offshore wind advanced technology demonstration projects off the U.S. East and West Coasts. This presentation will provide an overview of the capabilities of these buoys, scientific issues on which they will focus, means of accessing their data, and a timeline of their currently planned deployments.