Aesthetic, noise and vibration
Small wind turbines are favoured renewable and sustainable energy. In many countries, noise radiation is considered as the major limitation in the development of wind energy over the last years. Therefore, noise emission is one of the major concerns in wind turbine industry, especially SWTs one, which are mostly erected into the urban areas. Tonal noise emitted from the wind turbine installations, such as gearboxes or electrical power transmission parts, poses a serious environmental problem to the surrounding community, which is still a crucial point concerning the acceptance of WTs.
Tonality is a feature that may increase the adverse impact of a given noise source, and its evaluation is of high importance. Vibration is another factor to address within SWTs, due to the impact they may have depending on the location where the device is installed. The primary vibration excitation mechanism is resonance of the dominant whirling mode of the turbine, with the operating blade pass frequency. In addition, resonance of the airfoil support struts at higher frequencies too. Vibration transmitted to the anchorage of the WT might be dangerous depending on the supporting infrastructure.
Finally, aesthetic issues are key enablers for the social acceptance of these systems. Current society perceives beauty as a driver for the installation of anything in their close environment. Therefore, as social acceptance is key, aesthetics must be carefully treated.