Wind Atlas of Switzerland: Frequency of meteorological icing at 100 metres above the ground

In Switzerland, the mountain regions (Jura, Alps and Alpine foothills) are the most suitable regions for exploiting wind energy potential. But here, the air temperature during the winter months is frequently below 0° C for lengthy periods, and this can cause measuring instruments and rotor blades to ice up. Icing influences the planning and operation of a wind power plant in a variety of ways: ice formation on the rotor blades interferes with their aerodynamics and results in production losses. The additional weight and imbalance associated with ice formation also burden the structural elements of a wind turbine. For safety reasons (ice fall-off), and in view of the additional burden placed on their components, wind turbines have to be turned off when they ice up. Ice formation on a wind turbine’s measuring instruments can also give rise to faulty operation. Calculations of icing frequency are based on comprehensive data relating to cloud water, temperature and wind obtained from analyses of the MeteoSwiss COSMO-2 weather forecasting model. The icing model calculates the ice load on a cylindrical, freely rotating structure. The icing frequency is depicted on a 2.2-kilometre raster