Abstract: A Darrieus-type vertical axis wind turbine with tensioned blades is disclosed, along with various mechanisms for tensioning the blades. When the wind turbine is stationary in high wind conditions, the blades are tensioned to resist buckling. When the wind turbine is coming up to operational speed, or slowing down to a stop, the blades may also be tensioned to change the dynamic resonance characteristics of the rotor to avoid operation at resonant frequencies.

Abstract: A pultruded composite blade for a Darrieus-type vertical axis wind turbine is disclosed, along with a method for fabricating such a blade. The blade is a composite structure with a uniform cross-section with reinforcing fibers at least some of which extend parallel to a lengthwise central axis and run continuously from end to end. The composite blade is pultruded straight and, when installed on the tower, the blade is elastically bent into a curved shape that approximates a troposkein. The composite structure includes a skin composed of multiple layers of resin-coated glass fabric that define an airfoil shape. The composite structure also includes one or more internal ribs or spars composed of multiple layers of resin-coated glass fabric.

Abstract: A pultruded composite blade for a Darrieus-type vertical axis wind turbine is disclosed, along with a method for fabricating such a blade. The blade is a composite structure with a uniform cross-section with reinforcing fibers at least some of which extend parallel to a lengthwise central axis and run continuously from end to end. The composite blade is pultruded straight and, when installed on the tower, the blade is elastically bent into a curved shape that approximates a troposkein. The composite structure includes a skin composed of multiple layers of resin-coated glass fabric that define an airfoil shape. The composite structure also includes one or more internal ribs or spars composed of multiple layers of resin-coated glass fabric.