Types ofWind Turbines

Research Lab

Three Types:Horizontal Axis Wind Turbine (HAWT)

Vertical Axis Wind Turbine (VAWT)Unconventional/Nontraditional Wind Turbine

Horizontal AxisWind Turbine (HAWT)

Horizontal Axis Wind TurbineHorizontal Axis Wind Turbines (HAWTs), on the other hand, are very

advanced, reliable, and economically viable. They come in many sizes and shapes, but they are all descendents of the old windmills used to grind grain or pump water. Today these machines are proven: they are used throughout the world producing clean, affordable, and sustainable electricity. Modern horizontal axis wind turbines produce electricity 70-85% of the time (whenever the wind is over 7-8 mph).

Horizontal Axis Wind Turbines must be able to rotate to face the wind. This is called "yawing." The blades will not spin if the wind is hitting them from the side, so it is very important that the turbine can yaw. There are two ways a wind turbine can yaw: Active or Passive yawing.

Vertical AxisWind

Turbine (VAWT)

Vertical Axis Wind Turbine

• Vertical axis wind turbines (VAWTs) have advantages and disadvantages, but overall they have not been commercially successful like their cousins, the horizontal axis wind turbines (HAWTs). This is largely due to the poor performance and reliability of most VAWTs. However, there are practical applications for VAWTs and new research and technology is improving their performance.

Unconventional/Nontraditional

Number of Blades• Most wind turbines made today have three blades. Some

have more than three, some have less, but because of the physics of wind energy, turbine designs with three blades have proven to be the most efficient and economical.

• Wind turbine blades spin fairly slowly. The average rotation speed for large wind turbine rotors is 12-20 RPM. The slow rotation speed makes the turbines quieter and more aesthetic while having less environmental impact. However, this slow rotation speed makes the heavy-duty, expensive gearbox necessary.

• Large wind turbine blades are usually made of a hard, stiff composite material. Fiberglass, balsa wood, and carbon fiber are the most common materials found in wind turbine blades. The weight of the blades is very important, so they are designed using the lightest materials available. A single wind turbine blade can cost upwards of $100,000!