ECN part of TNO, KNMI (the Royal Netherlands Meteorological Institute) and Whiffle (a Delft University of Technology spin-off) have released the Dutch Offshore Wind Atlas. This new and improved map will help Dutch government and wind farm developers to plan, build and operate offshore wind farms even more efficiently.
The new and improved offshore wind atlas (DOWA) includes an unprecedented level of detail where the wind is mapped up-to 600 m in height and the daily variability of the wind captured for all to view. With DOWA, ECN, KNMI and Whiffle respond to the requirement for more detailed wind information. This is needed for a cost effective implementation of large scale offshore wind energy. As both wind speed and direction are highly variable across the sea, in time and in space, this can pose certain risks.
The new atlas provides more detailed information in order to reduce these risks. It comprises the following main features:
• Wind speed and direction information across the whole Dutch part of the North Sea, including the offshore wind development zones Borssele, Hollandse Kust Zuid and Hollandse Kust Noord
• Wind speed and direction information ranging up to an altitude of 600m
• Total coverage of 10 years up to 2017 and updated with 2018 wind information
• Spatial resolution of 2.5 km2 and wind information for every hour
The partners have applied state-of-the-art knowledge and modelling techniques. At the foundation DOWA makes use of leading numerical European Weather models available (e.g. the latest versions of European Center for Medium-range Weather Forecasts ERA5 and KNMI Harmonie) and takes inputs from existing measurement sources to obtain the best quality output. Furthermore, DOWA allows for connecting to the very fine scale forecasting models of Whiffle’s LES model ‘GRASP’ for detailed wind field and wind turbine resolving modelling. As a result, not only the wind turbine yield but also the wind turbine loading can accurately be assessed. DOWA now also outputs wind information at altitudes ranging up to 600m. Previous data was limited to 200m, insufficient for the next generation of wind turbines and future technologies operating at high altitudes.
DOWA was validated against offshore measurement stations as meteorological mast IJmuiden, fixed LiDARs on the offshore platforms Lichteiland Goeree, Europlatform and K13 and floating LiDARs in the offshore wind farm zones. Particularly, it demonstrates a mean wind speed deviation of less than 0.1m/s at all heights in the vertical wind shear profile up to 315m at the IJmuiden platform. Also, DOWA shows a very good representation of the daily cycle, where the accuracy in terms of model bias is improved by 16% as compared to previous data.