Abstract: The variable-geometry blade for use in a wind driven mechanism comprises a fixed blade portion and a movable winglet portion connected to said fixed blade portion and moveable with respect to said fixed blade portion along a direction substantially transverse to the axis of said fixed blade portion. A guide means is provided to guide the movement of said movable winglet portion with respect to said fixed blade portion, and an actuator means is provided for moving said movable winglet portion with respect to said fixed blade portion between a retracted position and an extended position.

Abstract: Power plant and process for the generation of electric energy through forced wind power. The plant includes a self-standing vertical structure, anchored to the ground, featuring a suitable diameter and height. Through this structure a powerful airflow operates one or more wind generators which is/are located inside. The plant is provided with several air inlets at the bottom, and an outlet at the top for discharging the air and at least one wind generator interposed between the afore-mentioned inlet-outlet. The tangible difference in the air density and temperature between high and low altitude generates a positive air flow moving from the bottom to the top and operates the internal generators regardless from the presence of winds or air flows. Suitable heating devices are located at the chimney bottom and boost the natural draught effect. A microprocessor controls the heating means in order to achieve a constant temperature at the air inlet and consequently a constant speed and a constant electric output.