Swift Wind Turbine is a quiet, rooftop mounted wind turbine. Unlike some designs you’ve seen previously, this one has an outer ring and five blades. The outer ring acts as a diffuser — the wind travels down the blades and is dispersed along the ring, therefore eliminating noise and keeping the turbine quiet. The company estimates a noise of less than 35 decibels for all wind speeds. The 7 foot diameter ring needs a roof line clearance of a couple feet and in good winds, can generate up to 2000 kWh of power (1.5 kW @ 14 m/s).