Waking between Planned Offshore Wind Farms

Wakes from wind farms can extend over 50 km downwind in stably stratified conditions (Platis et al. 2018; Lundquist et al. 2018), undermining power production and subsequent revenue from downwind wind farms. Offshore environments are especially susceptible to wake impacts, as laminar flow allows wakes to extend further downwind than they would onshore. Current US offshore lease plans promote the development of multiple wind farms within close proximity to one another, suggesting they will at times be operating in a waked environment.

Detailed modeling of the wind resource is required to understand and plan for these waking events, particularly for predicting wind generation for grid integration. The Weather Research and Forecasting (WRF) Wind Farm Parameterization (WFP) can represent wakes and has been validated with meteorological (Siedersleben et al. 2018a, b) and wind turbine power production measurements (Lee and Lundquist 2017) both onshore and offshore, and so is suitable for predicting wakes between these offshore wind farms in development.

We use this simulation tool to assess wake impacts between planned windfarms off the coast of Massachusetts for times concurrent with offshore lidar measurements at the Woods Hole Oceanographic Institute’s Air-Sea Interaction Tower (Bodini et al. 2019). The lidar measurements are used for model validation. The first test case spans several diurnal cycles during August 2017, characterized by southwesterly winds and high electricity demand. The second case from January 2017 is characterized by northwesterly winds with larger ambient turbulence. The analysis will quantify the magnitude and horizontal extent of the wind speed wakes, and will estimate the impact on power production.