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Jakob Mann
Risø National Laboratory for Sustainable Energy Denmark

August 24, 2010
Foothills Laboratory 2, Room 1001
Lecture 10:30am

Lidar Measurements for Wind Energy

Wind lidars (light detection and ranging) have manifested themselves as powerful tools to measure the mean wind over flat terrain for wind resource estimation. They can essentially replace meteorological towers for that purpose, but there are many additional opportunities for lidars in wind energy research. It would be advantageous if lidars could be used to give reliable information on turbulence intensity, which would increase their usefulness as tools for wind turbine siting. The main problem with that is the spatial averaging of the turbulent wind field, which is carefully studied experimentally and explained theoretically through application of the spectral velocity tensor. Different ways of analyzing the lidar data produce very different attenuation of the statistics depending on how the information from the various beams is combined. Also, lidars mounted on the nacelles, blades or hubs of turbines bear promise of more efficient turbine control for improved power production and reduced mechanical loading due to wind gusts. This last opportunity requires detailed investigation of Taylor's frozen turbulence hypothesis. Finally, several lidars will be combined to produce a "wind scanner" which can be used to scan the three-dimensional wind flow around terrain features, or a wind turbine as well as other relevant atmospheric flows.