The wind energy index we can provide you with will be a “historic” overview of how much wind could have been utilized by a WTG on the location in question. Index 100 indicates a completely average month or year based on e.g. 10 years of wind data, whereas an index of 90 will indicate 10% below average. The index will be based on detailed studies of the shape of the landscape (the height contours) in a radius of 5 km around the Met mast and a study of how the nature of the landscape (the “roughness” and local obstacles) will affect the Met mast. Roughness is evaluated in a radius of min. 20 km and local obstacles in a radius of 1000m.
In addition to that the monthly average temperature, based on long-term measurements is taken into account and finally the data is filtered through a generic power curve.
In a spread-sheet (MS Excel) which can be delivered it is also possible to enter new wind data from the Met masts in question and get an index number out e.g. for May 2001.
In Denmark it is very common to base production guarantees on calculated/predicted production – 10% IN A NORMAL WIND YEAR. In many of the big wind energy countries like Denmark and Germany, literally thousands of WTG owners are using such an index every month in order to get an indication of how well their single WTG or wind farm is performing.
In this lecture I will present our experiences with the calculation and creation of wind energy index’s evaluation of wind measurement with emphasis on the following subjects.