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Yield index

 

The most important external influencing factor for wind turbines is wind speed. It varies constantly and is therefore one of the central technical and economic uncertainties in the use of wind energy. Apart from short-term fluctuations, there are also significant deviations between the annual values and the long-term averages. There are also regional differences in terms of geography and topography. It thus becomes essential to categorise the individual years within the longer-term course of wind conditions. A yield index is suitable for this, in which the wind conditions are linked to the technical data for a wind turbine, thus highlighting the differences between the wind years. The figure shows the 2017 yield for Europe in relation to the 20-year average based on the yield calculation for an exemplary Vestas V90 wind turbine with a hub height of 100 metres and a rated capacity of 2 MW. The 2017 yield index shows average to above-average wind conditions for Northern and Eastern Europe and parts of Western and Southern Europe. Only France, the Benelux countries and Spain were almost entirely affected by below-average conditions.

 

 

 

 

Wind resources in 2017 (20x20 km resolution) for Europe in relation to 20-year average based on MERRA-2-Data

Data source: [anemos GmbH]

 

 

The following figure shows a higher-resolution yield index for Germany. In most parts of Germany, the yield index in 2017 was over 95 percent of the long-term average. Significantly below-average wind conditions can primarily be seen in North Rhine-Westphalia, Hesse, Rhineland-Palatinate and Saarland. After the low-yield year 2016, 2017, like 2015, can be categorised as a rather windy year overall. Above-average wind speeds in the German states with a high density of wind turbines in northern and eastern Germany resulted in good overall yields.

 

 

 

 

 

Wind resources in 2017 (3x3 km resolution) for Germany in relation to 20-year average based on MERRA-2-Data

Data source: [anemos GmbH]