Wind energy moves over the Earth's surface as kinetic energy. This energy is received by the blades of a turbine, which is attached to an electrical generator that sits atop a collection tower. Collection sites consist of a single turbine, or many, constituting a wind farm.
Each turbine consists of a tower structure, rotor with blades attached to the hub, shaft with mechanical gear, electrical generator, yaw mechanism, and sensors and control. Modern structures must come equipped with a control system for operational and safety functions.
Certain terms are necessary to understanding of the wind industry. The gearbox increases the turbine speed from around 45 rotations per min. (rpm) to about 14,500 rpm. The rotor connects to the nacelle, which sits atop the tower and contains the gearbox. Upwind refers to a turbine operating facing the wind in front of the tower. Downwind turbines run facing away from the wind behind the tower. Finally, the yaw drive maintains the direction of the upwind turbine facing the wind.
The tower is the support structure. It can be steel or concrete, and tubular or lattice. They must be at least 82 ft. (25 m.) tall to capture adequate energy. The turbines range in size from a few kW to a few megawatts (MW), used for utility-scale power generation. Turbines usually consist of two or three aerodynamic blades constructed to capture the most energy possible. The blades operate using the Bernoulli principle. A lift is created by the difference in pressure on the sides of the blades when the wind flows over it. The lift rotates the blades around the hub. A drag force is created that acts perpendicular to the blades and slows down the rotor. The purpose of this design is to achieve the highest drag to lift ratio, optimizing the turbine's power.
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Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.