The blades are made of fiberglass, sometimes with Kevlar reinforcement. They are hollow and their shape is designed to achieve the best aerodynamic conditions, maximum efficiency and minimum noise generation during movement. When wind flows across the blade, the air pressure on one side of the blade decreases. The difference in air pressure across the two sides of the blade creates both lift and drag. The force of the lift is stronger than the drag and this causes the rotor to spin. Most turbines have three blades.
