Resource Assessment Methods in the Offshore Wind Energy Sector

Abstract

Offshore wind industry has experienced a large development over the past decades. Some key factors in the development, sitting and operation of an offshore wind farm include the accurate estimation and forecast of the wind resources and the quantification of the inherent variability in wind power generation. Wind resource estimates are characterized by various degrees of uncertainties that could lead to highly misleading results. Most often, risk-based financial models on which wind project investments are based, are strongly dependent upon these uncertainties, which constitute a barrier for wind energy penetration into the electricity grid. On that account, for a correct and reliable wind power assessment it is of utmost importance to increase the quality and quantity of wind data available. An accurate estimation of wind field is a challenging task that requires reliable sources of data. Offshore meteorological observations from meteorological masts or marine buoys constitute the most commonly used source of data to build energy density maps due to its large reliability. Nevertheless, in situ measures are often sparsely located, not available where the observations are most needed, and have a poor temporal coverage. To overcome these limitations, the wind field may be obtained from a variety of alternative methods available for energy assessment, from satellite remote sensing observations to numerical weather prediction models. This paper gives an overview of the available methods for addressing the wind resource and overall development potential of a candidate site together with a review of the statistical methods to deal with variability and long-term extrapolation of wind speed time series. Finally, the present and future challenges and perspectives are addressed and identified, highlighting the reforms that may be crucial in the forthcoming period.