Validating LES turbulence intensity for use in offshore wind

Turbulence intensity (TI) is a required input for wind farm design. TI impacts wake recovery, and therefore project economics, and is needed for turbine site suitability. Measuring TI for offshore wind projects is challenging as current measurement techniques are either very expensive and slow to deploy (offshore met towers) or are unreliable to turbulence measurements (lidar buoys). Without a reliable method for measuring TI an alternative approach for quantifying offshore turbulence is needed to continue advancing the offshore wind industry in the US. Large eddy simulation (LES) modeling is increasingly used to supplement offshore measurement campaigns. In this study LES simulations from the GPU-Resident Atmospheric Simulation Platform (GRASP) model are considered as an alternative source of offshore TI values. Results include validation of GRASP against hub height measurements from at least eight locations in the US and Europe with a focus on TI and, when available, atmospheric stability metrics. This study considers an LES only approach to TI, as well as a hybrid solution where LES output is combined with mean wind speed measurements to generate improved TI values. Application of LES TI will be considered both for early-stage wind yield assessments, and for wind turbine site suitability analysis.