Offshore wind power potential and capacity density assessment in Utsira Nord

Abstract

Optimizing offshore wind farm design with regard to minimal wake loss is important to ensure the success of offshore wind projects, as well as effective utilization of ocean resources. The thesis study the offshore wind power potential in Utsira Nord, by investigating how capacity expansion and turbine distance affect wake loss. The analysis is carried out using the modular wind farm and wake modelling Python package FOXES for different wind farm layouts. The results reveal that the common practice of using a constant turbulence intensity of 5\% overestimates the power production compared to using calculated turbulence intensity from given wind data, with increasing deviations for increasing installed capacity. Furthermore, comparing three scenarios of different installed capacities proposed by the government and NVE suggests that adding an additional project area is a more energy-efficient method of capacity expansion than increasing the number of turbines within existing project areas, due to the dominant internal wake loss. A capacity density analysis for the three scenarios reveal decreasing internal and increasing external wake loss for growing turbine distance, as the wind farm size expand and cause less distance between the areas. In contrast, using full utilization of the designated areas result in both internal and external wake reduction as the turbine distance grow. The overall wake loss decreases in both cases, with significant improvement in the lower range of 2D-7D, while the effects gradually becomes less significant in the upper range for 8D-15D. A constant turbine distance of 7D is shown to provide a good balance between high power production and relatively low wake loss. An alternative farm layout that consider the dominating wind direction cause further wake loss reductions.