As early as 3000 B.C., people used wind energy for the first time in the form of sail boats in Egypt. Sails captured the energy in wind to pull a boat across the water. The earliest windmills, used to grind grain, came about either in 2000 B.C. in ancient Babylon or 200 B.C. in ancient Persia, depending on who you ask. These early devices consisted of one or more vertically-mounted wooden beams, on the bottom of which was a grindstone, attached to a rotating shaft that turned with the wind. The concept of using wind energy for grinding grain spread rapidly through the Middle East and was in wide use long before the first windmill appeared in Europe. Starting in the 11th century A.D., European Crusaders brought the concept home with them, and the Dutch-type windmill most of us are familiar with was born.
Turbines today are sleek and slender machines, a far cry from their wooden ancestors. Around the world, wind turbines of all sizes have become a familiar sight; ranging from home or farm-scale machines of 1 kilowatt (kW), all the way up to arrays of large 7 megawatt (MW) machines for off-shore use.
Modern wind turbines are up to the task of producing serious amounts of electricity. A popular sized machine in the U.S. today is a state-of-the-art 2 MW turbine that stands as tall as a 30-storeys building and costs roughly $4 million to $5 million installed. With a good wind resource, this size turbine can produce 5 million kWh of electricity each year, or enough energy to run 500 average American households.