Experimental study of the environmental impact for improving the performance of horizontal axis wind systems

Wind energy plays a crucial role in reducing dependence on fossil fuels; however, noise pollution generated by wind turbines remains a major concern for nearby populations and often limits social acceptance. This study presents an experimental assessment of wind turbine noise based on in situ measurement campaigns conducted at three onshore wind farms under controlled meteorological and geometric conditions. Sound pressure levels were recorded at distances ranging from 200 m to 1500 m and at receiver heights of 2 m and 4 m, considering both direct line-of-sight and ground effect propagation. The results show a progressive attenuation of noise with increasing distance, while differences between direct and ground-effect measurements remain limited, not exceeding 2.4 dB (A) at 1500 m. At this distance, noise levels generally fall below typical background thresholds, even under the most unfavorable propagation conditions. These findings provide empirical evidence supporting distance-based mitigation strategies and contribute to the improvement of setback distance recommendations and noise management practices for wind farm development.