Abstract: A wind energy device comprising a first airfoil having a leading edge, a trailing edge and a tip, means supporting the airfoil above a surface, the airfoil being adapted, when traversed by a prevailing wind, to generate a vortex at its tip, an air deflector associated with the airfoil and arranged so as to deflect prevailing wind traversing the deflector into the vortex to augment the energy of the vortex, means to vary the orientation of the airfoil relative to the prevailing wind, and a rotary device located in the path of the vortex and adapted to be driven by the wind in the vortex.