In the Dutch Offshore Wind Atlas (DOWA) project that was launched in June 2017 and has last until December 2019, TNO, KNMI (the Royal Netherlands Meteorological Institute) and Whiffle (a Delft University of Technology spin-off) have combined their expertise and knowledge of wind conditions and wind energy. TNO was leading this DOWA-project that has been commissioned by the Dutch national government. The aim was to make the new and updated atlas available for use in tenders for new offshore wind farms off the southern Holland coast (Scheveningen) and the coast further north (Egmond).

TNO, KNMI and Whiffle have worked on a new atlas featuring accurate information about North Sea winds for wind energy applications. Clarity with respect the amount of wind enables a more accurate estimate of an offshore wind farm’s yield and clarity on how often wind speeds reach extreme levels determine how robust wind turbines need to be made. This reduces the cost of offshore wind energy, a key target set by the Dutch government. Each organisation will contribute with its own specific expertise.

TNO has specific knowledge of the wind conditions affecting wind turbines and wind farms and KNMI brings its specialist wind climate knowledge with the help of weather models. Whiffle has developed software that can calculate local wind information at a very high resolution.

Various levels of modelling and their validation

Better understanding wind conditions

In the DOWA project KNMI has extended the existing KNMI North Sea Wind (KNW) atlas cataloguing wind information up to an altitude of 200m to include information from 2014 until March 2019, enabling the dataset to be used to predict wind energy production in wind farms now in the planning phase. In addition, KNMI compiled a new atlas known as the Dutch Offshore Wind Atlas (DOWA). Based on improved models and methods, the new atlas more effectively chart changes in the wind within a 24-hour period (day/night) and provides wind information from layers of air at a higher altitude (600m). TNO has validated this atlas using accurate wind measurements from offshore meteorological mast, LiDARs on platforms, floating LiDARs and from satellites and aircraft. In doing this, TNO creates a better understanding of the offshore wind conditions, particularly at higher altitudes.

Using the DOWA output, Whiffle software makes it possible to extrapolate extremely accurate wind information. The DOWA project also focuses on the wind in the lee of an individual wind turbine or complete wind farms. Last but not least, TNO has purchased LiDAR (Light Detection and Ranging) equipment that makes it possible to use laser techniques to scan wind fields at an altitude of several kilometers. As wind turbines increase in size, wind measurements at greater altitudes are becoming increasingly important.

KNMI has continually updated the KNMI North Sea Wind (KNW) atlas from 2014 onwards and makes these data available. The DOWA results have been made available in a similar fashion. The availability of these more recent modelled wind data is valuable for offshore wind farm developers because it enables the dataset to be used to estimate wind energy production in wind farms in the planning phase. In particular the ability to correlate the dataset with recent offshore measurements with LiDAR enables uncertainties to be reduced.

Watch the DOWA webinar

Watch the video

If you are interested in the atlas data, please visit the KNMI Data Centre

KNMI Data Centre

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Dr Jan Willem Wagenaar