Analyses of wind turbine performance from high-alpine installations are scarce. We present characteristics of the power curve of one small wind turbine installed on a mountain shoulder near Lukmanier Pass and five large wind turbines located along the Gotthard Pass. On-site measurements are combined with LiDAR data to analyse the influence of turbulence intensity, temperature and snow cover on wind turbine performance. These conditions are known to vary strongly in alpine environments and to differ from typical installations at low elevations. Based on observational data, we aim to explain the seasonal characteristics and to verify the viability of mountainous regions for wind energy production. We find a small positive influence of highly turbulent winds at low wind speeds and show that the effect becomes negative at high wind speeds. At low wind speeds, very high turbulence intensity ( > 0.35) can partly counterbalance the effects of reduced air density. In this regime, small wind turbines profit most, as near-surface winds are typically more turbulent due to terrain-induced effects. In contrast, at high wind speeds, very low turbulence intensity ( < 0.1) is required to maintain maximum power output, a condition more generally met by large wind turbines operating at greater hub heights. Both low temperature and the presence of snow cover are found to have a positive influence on wind turbine performance, especially for small ones. This behaviour is attributed to a combination of increased air density and atmospheric stability at low temperature, while snow cover may additionally smooth surface roughness. The benefits of snow cover are found to reverse at higher wind speeds once correlated effects are accounted for. The small wind turbine is found to particularly benefit from higher turbulence and snow, as they impact the wind flow over a larger part of the rotor area, whereas the effects are less pronounced for large wind turbines. Overall, the small wind turbine and some of the larger ones show a good performance, supporting their potential in alpine regions. • Performance of wind turbines in high alpine conditions is analysed. • LiDAR and wind turbine data are combined. • High turbulence boosts performance at low wind speeds, but not at high ones. • Wind turbines perform better with a snow cover and with low temperatures. • The results are particularly true for small wind turbines.
Gasser et al. (Thu,) studied this question.