Towards the North Sea wind power revolution

Abstract. The present work assesses the potential of a massive exploitation of offshore wind power in the North Sea by combining a meteorological model with a cost model that includes a bathymetric analysis of the water depth of the North Sea. The overall objective is to assess if the wind power in the North Sea can deliver the total consumption of electricity in Europe and to what prize as compared to conventional onshore wind energy. The meteorological model is based on the assumption that the exploited area is so large, that the wind field between the turbines is in equilibrium with the atmospheric boundary layer. This makes it possible to use momentum analysis to determine the mutual influence between the atmospheric boundary layer and the wind farm, with the wind farm represented by an average horizontal force component corresponding to the thrust. The cost model includes expressions for the most essential wind farm cost elements, such as costs of wind turbines, support structures, cables and electrical substations, as well as operation and maintenance as function of rotor size, interspatial distance between the turbines, and water depth. The numbers used in the cost model are based on previous experience from offshore wind farms, and is therefore somewhat conservative. The analysis shows that the lowest energy cost is obtained for a configuration of large wind turbines erected with an interspatial distance of about eight rotor diameters. A part of the analysis is devoted to assessing the relative costs of the various elements of the cost model in order to determine the components with the largest potential for reducing the cost price. As an overall finding, it is shown that the power demand of Europe, which is 0.4 TW or about 3500 TWh/year, can be fulfilled by exploiting an area of 190.000 km², corresponding to about 1/3 of the North Sea, with 100.000 wind turbines of generator size 13 MW on water depths up to 45 m at a cost price of about 7.5 €cents/kWh.