Abstract: A turbine type power generator includes a rotor having a vertical shaft to drive a load which may be an electric generator or mechanical gear train or other device for using or transmitting power. Generally vertically extending blades are secured at their ends to the rotor shaft and are set at an angle to the relative wind to be driven thereby. The rotor is surrounded by wind controlling shield means through which the air flow passes to contact the blades in the proper direction for causing rotation. The free flow air inlet area is substantially less than the maximum projected area of the shield means normal to the relative wind so that the total wind trapped must flow through a reduced area with a consequent increase in velocity to impart more energy to the rotor blades. One form of shield means is a structure of the same general shape as the rotor surrounding the rotor on all sides and having vertically extending passages spaced around its perimeter to lead the air flow to the blades.