How does mesoscale wind variability affect the financial and technical value of proposed wind farms? If a developer had to choose between two otherwise identical sites, but knew that one of them was subject to intense and frequent mesoscale wind variability, would this influence planning decisions?

Wind farms such as Horns Rev in the North Sea and Nysted in the Baltic Sea often experience large fluctuations in wind speed on time scales of around one hour. For a large wind farm, this variability, known as 'mesoscale variability', can result in large fluctuations in power output. Sudden and unexpected changes in wind farm power production must be balanced by expensive reserve power. The figure shows an example of a 5 day period when large wind speed observations were observed at the Horns Rev wind farm.

timeseries

As the number of large offshore wind farms in Denmark and neighbouring countries increases, the potential impact of persistent wind speed fluctuations becomes more critical. In fact, the frequency and intensity of wind variability could become a new siting criterion for wind farms, together with existing criteria such as mean wind speed or proximity to suitable grid connection points.

Observations from a single location only show one aspect of hour-scale wind variability. Spatial and physical description of variability requires state-of-the-art treatment, using both high-resolution meteorological modelling and careful analysis of newer observation sources such as satellites.

In this project I will develop new methodologies for observing, modelling and mapping wind variability, with reference to practical challenges faced by large, modern, offshore wind farms. I will produce an atlas of mesoscale wind variability, which can potentially become important supplementary information for siting large offshore wind farms.