Wind power is primarily used in modern applications to power electricity generating modern windmills. American wind energy installations now have more than 10,000 megawatts (MW) of generating capacity, producing enough electricity on a typical day to power the equivalent of over 2.5 million homes. In 2006, an additional 3000 MW of winf energy wil be installed.
Historically, windmills were used to turn stones to grind grain (hence the name), to pump ground water in rural areas, and to power ships with sails. Wind power generation is renewable and non-polluting. One drawback, however, is the size of the machinery required to extract significant energy from the wind. Although the proportion of total electrical power coming from wind in the United States is still small, wind has probably made more progress than solar power as a renewable and non-polluting electricity source. Wind is also not an "on demand" generation source because the wind can be fickle, so energy produced by wind must be stored in some manner, or serve as a supplement to "base power" supplies which can be adjusted.
An important limitation of wind power is that many of the best land-based locations of wind power electricity generation, e.g. in the Great Plains of the U.S., are distant from population centers. The waste involved in trying to send wind power generated in Nebraska to say, Chicago, is cost prohibitive. A number of windfarms in Europe are located offshore, where winds are often high, and populations are often concentrated around sea coasts.
Denmark is today the world's leading wind power economy, with this clean, renewablke energy source suppling 20% of the total Danish electricity consumption. Exports of wind energy technology are also important for the Danish economy, bringing in 3 billion Euros annually and employing 20,000 people.
Typical wind machines:
A good rule of thumb is that it costs about USD $1 Million per megawatt of generation power. So, the roughly $100 billion the US spends each year in Iraq would have been enough money to build 100 gigawatts of generating capacity, or approximately 66,667 GE wind machines. Given that a typical wind turbine has an output of only about 25% of its capacity, that would provide an average of about 600 GWh per day which is the equivalent of approximately 350,000 barrels of oil per day, about 4% of our daily import. Less than 2.4% of our oil use is for electricity generation, so it isn't really relevant except for the sake of comparison.
Because of the variability of the wind, and the fact that output increases (and decreases) in cubic relation to the wind speed, roughly two-thirds of the time output would be much less than average. And because there would be many times when wind production would be virtually nil, no other sources are actually displaced by wind power and may end up being operated less efficiently, i.e., with more pollution, unless peak wind power can be efficiently stored, for example, by pumping water which is later used to power hydroelectric turbines or by electrochemically producing hydrogen for later use in a fuel cell, although each of these involves a significant loss of energy, further cutting into wind power's already low capacity factor.