A wind turbine comprises an impeller and a turbine shroud disposed about the impeller. The impeller surrounds a center body having a central passageway through which air can flow through the center body to bypass the impeller. The impeller comprises a central ring and a plurality of impeller blades extending therefrom. When air passes through the impeller blades, some of its energy is used to turn the blades. The reduced-energy air is then mixed with the air flowing through the central passageway. This mixing allows the operating efficiency of the turbines to routinely exceed the Betz limit.
