Stochastic investigation of the effect of offshore wind farms on surface waves

A. Trompouki, Stochastic investigation of the effect of offshore wind farms on surface waves, Diploma thesis, 91 pages, Department of Water Resources and Environmental Engineering – National Technical University of Athens, Athens, September 2022.

[doc_id=2269]

[Greek]

The offshore market is gaining ground among others in the last decade, as the world is heading towards green energy, decarbonization and energy independence. The exploitation of the ocean energy seems to be promising, with hybrid systems (ocean underwater turbines, offshore wind parks, floating panels) achieving high capacity factors of energy production. The analysis of the wave and the wind field is essential for the design of the above projects. Though the experience in the field is yet minimum, researchers begin to study the combined behavior of wind and waves in coupled atmospheric-ocean models. The direction and intensity of wind affects the wave characteristics and their interaction defines the wake effect of offshore structures. This work focuses on this effect for wind and wave fields downstream an offshore wind farm, using satellite data for an existing wind park; the London Array project. In more detail, the first four central moments are calculated for the inclusive area of the wind park and the potential effect on the seasonality of wind and wave variants is examined. Also, an added value of this research is the estimation of the temporal and spatial dependence of the variants, through the 1-D and 2-D Climacograms. Finally, a synthetic time series is computed for the variant of wind speed, adding a stochastic dimension to the phenomenon. The extracted data from the analysis are compared and in-line with the existing literature. The reduction of the significant wave height and wind speed around the park are on the same size-scale and the variants maintain a strong spatio-temporal dependence in higher scales. The impact of the park on the behavior of wind and waves is negligible, when compared to the climatic variances. Overall, the examination and better understanding of the phenomenon is crucial for the design of offshore structures, as for the case of wind farms, the downstream flow affects the performance of the park. Last but not least, the conclusions made are important for the evaluation of the environmental impact in the area.

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