ASSESSMENT AND COMPARISON AMONG PREDICTION METHODS FOR THE LOW FREQUENCY NOISE PRODUCED BY WIND TURBINES: APPLICATION TO A CASE STUDY

The present energy scenario leads to an acceleration in the development of the exploitation of renewable sources. Latest regulations impose higher and higher percentage shares of energy from renewable sources. The current technological advancement stresses the wind energy as an energy source endowed of a special reliability. The technology to take advantage of such a source is based on large size wind turbines, with a rated power of about 3 MW. Among the main environmental problems that have to be faced in planning a new wind farm, the acoustic impact stands out. It consists of noise engendered by wind turbines with a special effect of noise emitted at the low frequency spectrum. Recently Denmark has produced a new regulation which calls for specific procedures for the assessment of noise at low frequencies. Purpose of the present work is to take stock of the procedures currently employed in the predictive study of the low frequency noise produced by wind turbines. The analysis was carried out by applying the expounded procedures to a real case situated in Sardinia. It concerns a wind farm formed with 21 large size turbines, where a comparison between the results obtained by applying the procedures of ISO 9613 and those provided for by the Danish regulation is shown.