The influence of non-logarithmic wind speed profiles on potential power output at Danish offshore sites

Authors

  • M. Motta,

    1. Department of Wind Energy and Atmospheric Physics, Risø National Laboratory, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
    Current affiliation:
    1. Servizio Agrometeorologico Regionale per la Sardegna (SAR), Sassari, Italy
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  • R. J. Barthelmie,

    Corresponding author
    1. Department of Wind Energy and Atmospheric Physics, Risø National Laboratory, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
    • R. J. Barthelmie, Department of Wind Energy and Atmospheric Physics, Risø National Laboratory, Frederiksborgvej 399, DK-4000 Roskilde, Denmark
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  • P. Vølund

    1. Energi E2 A/S, Copenhagen, Denmark
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Abstract

Detailed knowledge of mean wind speed profiles is essential for properly assessing the power output of a potential wind farm. Since atmospheric stratification plays a crucial role in affecting wind speed profiles, obtaining a detailed picture of the climatology of stability conditions at a given site is very important. In the present study, long time series from offshore measurement sites around Denmark are analysed, with the aim of quantifying the role of atmospheric stability in wind speed profiles and in our ability to model them. A simple method for evaluating stability is applied, and the resulting statistics of the atmospheric stratification is thoroughly studied. A significant improvement in the mean wind speed profile prediction is obtained by applying a stability correction to the logarithmic profiles suitable for neutral conditions. These results are finally used to estimate power densities at different heights. Copyright © 2004 John Wiley & Sons, Ltd.

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