Wind Energy

Wind power is the kinetic energy of wind, or the extraction of this energy by wind turbines. In 2004, wind power became the least expensive form of new power generation, dipping below the cost per kilowatt-hour of coal-fired plants. Wind power is growing faster than any other form of electrical generation, at about 37%, up from 25% growth in 2002. In the late-1990s, the cost of wind power was about five times what it is in 2005, and that downward trend is expected to continue as larger multi-megawatt turbines are mass-produced.

This article deals mainly with the intricacies of large-scale deployment of wind turbines to generate electricity.

An estimated 1 to 3 percent of the energy from the Sun is converted into wind energy. This is about 50 to 100 times more energy than what is converted into biomass by all the plants on earth through photosynthesis. Most of this wind energy can be found at high altitudes where continuous wind speeds of over 160 km/h (100 mph) are common. Eventually, the wind energy is converted through friction into diffuse heat all through the earth's surface and atmosphere.

While the exact kinetics of wind are extremely complicated and relatively little understood, the basics of its origins are relatively simple. The earth is not heated evenly by the sun. Not only do the poles receive less energy from the sun than the equator does, but dry land heats up (and cools down) more quickly than the seas do. The differential heating powers a global atmospheric convection system reaching from the earth's surface to the stratosphere which acts as a virtual ceiling.

The change of seasons, change of day and night, the Coriolis effect, the irregular albedo (reflectivity) of land and water, humidity, and the friction of wind over different terrain are some of the many factors which complicate the flow of wind over the surface.