Abstract

without any restrictions for the following generations. In these concepts the wind energy and wave/ocean current energy are important factors as the description and the prognosis of waves and currents is a complex issue, especially offshore. For the estimation of the average annual wind speed and thus the energy production of offshore windfarms, it is imperative to know the exact wind conditions at each project site. Suitable prognosis methods are either missing so far, or not accurate enough, or at beta stage. The only possibility to achieve exact information about the offshore conditions is a metocean station consisting of wind and wave sensors. These met stations can be lattice masts mounted on monopiles or buoys equipped with meteorological sensors, both in combination with wave sensors to include all important parameters. Though conventional metocean stations are far more common, established and are measuring data of high quality, cheaper and more flexible solutions such as the likes of floating light detection and ranging are about to be used during the operation of wind farms. This article explains currently used methods of offshore measurements with respect to wind and wave and compares it with reanalysis data. This data has advantages in comparison to measurements from conventional metocean stations, but cannot be used independently. This article proves that using solely reanalysis data is not possible, that measurements offshore are still necessary and that its operation helps in improving the performance of offshore wind farms.