Just how noisy are wind turbines?

“We want to compute the complete chain of effects from the plant to the population,” Theodoros Triantafyllidis, Coordinator of the TremAc cooperation project and Head of the Institute of Soil Mechanics and Rock Mechanics of KIT, explained. Within the framework of the TremAc cooperation project, a single chain is to be developed for modelling all vibrating plant components and the surroundings, i.e. the rotating rotor blades, drive shaft, gondola suspension and tower structure, foundation and the ground, various topographic terrains and airflows as well as adjacent residential buildings and workplaces.

The scientists plan to measure the vibrations propagating in the atmosphere as acoustic and in the ground as seismic waves both for a single wind turbine and in a wind park, and to validate the computation models with these data. In parallel, the neighbouring population will be interviewed using environmental medicine and psychological questionnaires. The people’s subjective complaints will be related to objective measurements in buildings.

So far, the emission and perception of noise and vibrations has been studied separately in most cases. “This is far too limited in scope to understand why neighbours complain of inconveniences caused by wind power plants even though the required limit values are observed and people should not hear anything physiologically,” Triantafyllidis added. For this reason, the TremAc project will concentrate on studying interactions between airborne sound and structure borne sound.

The coupled computation models to be developed under the project will help better prognosticate emissions of planned wind power plants and realistically define and continuously review limit values as a function of the plant output, the distance to residential buildings and topography. In addition, the engineers want to analyse the interactions of individual plant components and the causes of emissions as well as to develop technical solutions for minimising structure borne and airborne sound. Finally, assessment criteria are to be objectified by the cooperation of engineers and social scientists.

The TremAc (Objective Criteria for Vibration and Noise Emissions of Inland Wind Power Plants) cooperation project was initiated by the South-German WindForS research cluster. The partners are Karlsruhe Institute of Technology, the University of Stuttgart, Technische Universität München, the University of Bielefeld, the University of Halle-Wittenberg and the company Mesh Engineering, Stuttgart.