You don’t see them around our neck of the woods very often, but windmills are more frequently being used to generate electricity.  There are several reasons for this:

  • There is a need for new sources of energy as fossil fuel reserves are declining
  • Wind is in abundance all over the world
  • Technological advances have made windmills highly efficient, meaning wind-generated electricity can be profitably produced

Today’s windmills are actually wind turbines, as a turbine is something that can generate electrical power.  Wind turbines convert wind into electricity.  Simply stated, when the wind passes through the windmill’s blades, the blades experience a lift due to their aerodynamic foil shape.  As a result of the lift, the blades start rotating, with a yaw unit aligning the blades toward the incoming wind direction.  The blades spin a shaft.  The shaft is connected to an electric generator.  The generator converts the energy to electricity.  The electricity is then added to the power grid.

There are two types of wind turbines: horizontal wind turbines and vertical wind turbines.  The horizontal-axis turbine, which is the kind we are most used to seeing, typically has a three-blade vertical propeller that catches the wind head-on. The vertical turbine has a set of blades that spins around a vertical axis.

Most major energy developers prefer horizontal turbines.  They are simpler to understand and meet the expectations of what a wind turbine should look like. Vertical-axis generators also have historically been the object of exaggerated claims.

Wind turbines also range in size from 100 kilowatts to several megawatts, although turbines below 100 kilowatts  are available for homes, telecommunications dishes and water pumping.  These are usually found in remote locations where a connection to a utility grid is not available.

Larger turbines are often grouped together into wind farms, which provide bulk power to a grid.  There has also been an increase in the use of offshore wind installations off the coast of the United States.