Wind turbine blades are a key component of a wind turbine. Wind turbines are machines that turn wind energy into mechanical energy. The mechanical energy is then converted to electricity. Large utility-scale wind turbines use rotating wind turbine blades to generate that power.
Utility-scale wind turbines have over 8,000 parts. The turbines rotate around either a horizontal axis or a vertical axis. Horizontal-axis wind turbines (HAWT) are more common than vertical-axis wind turbines (VAWT). An HAWT can be up to 50 percent more efficient than a VAWT, because of design and location factors.
A VAWT has a vertically arranged motor shaft located close to the ground. Wind speed is slower at lower altitudes, limiting available wind energy. Also, VAWT blades rotate into the wind, creating additional and inefficient drag.
The HAWT evolved from the European four-bladed wood and fabric windmills. Modern large wind turbines use three blades because, aerodynamically, an odd number of blades is more efficient. Each wind turbine blade is approximately 65 to 130 feet (20 to 40 m) long.
The blades are produced from strong laminated materials that have a high strength-to-weight ratio. Balsa, wood, fiberglass and carbon fiber can all be molded into airfoils. The wind turbine blades are painted light gray to blend in with clouds.
HAWT rotor shafts and generators are mounted on vertical towers and pointed into the wind. The high-tech wind turbine blades are bolted to a hub weighing 8 to 10 tons (7.25 - 9.1 tonnes). A pitch mechanism allows a wind turbine blade to rotate on its axis to exploit varying wind speeds. Computer-controlled motors point the blades at optimal angles.
Adjusting the blade position provides greater control, allowing the wind turbine blades to reap the maximum amount of wind energy. The blades are always perpendicular to the wind, so they receive power throughout the entire rotation. A HAWT rotor component, including the wind turbine blades, makes up approximately 20% of the cost of manufacturing a utility-scale wind turbine.
The best wind is sometimes found in remote areas, where it can be too expensive to put wind turbines. The weight and size of the components make transporting parts a main factor in location decisions. Wind turbine towers are typically 200 to 300 feet (61 - 91.4 m) tall and constructed from tubular steel. The wind turbine blades are transported separately, with the tower and the engine requiring two additional trips.
Multiple large wind turbines grouped together form a wind farm. Wind farms can produce electric power for commercial production from a land or off-shore base. A wind farm can require hundreds of square miles (square kilometers), but the space between turbines can be used for other purposes.