Wind Farms

Green energy is supremely important today. For the last 40 years, policymakers in the U.S. and other countries have sought a way to reduce dependence on non-renewable fossil fuels such as coal and oil. A variety of alternatives have been introduced, most notably nuclear plants and hydroelectric dams, which provide 5.8% and 2.2%, respectively, of the world's total energy. Although other sources, including geothermal, solar, and wind power, still represent less than 1% of the electricity generated for the world (0.7% in 2008), implementation of these renewable resources has increased seven-fold since 1973.

Why not use the power of the wind, which has been harnessed by many cultures over the past 4000 years? Windmills were probably developed as far back as the third millennium B.C.E. in China, but the first proof of their existence was in the 6^th century C.E. in Persia. These early turbines had a vertical (up and down) axis around which the sails were pushed by the wind; horizontal axis windmills were not seen before the 13^th century C.E. These are the type most people recognize today in the Dutch windmills as well as the turbines found on wind farms.

Most windmills were used to pump water and to grind wheat and other grains; later they provided mechanical energy for other tasks such as refining and processing tobacco, spices, and coffee, as well as sawing timbers (the sawmill). As time passed, the windmills were gradually refined to become more efficient. For example, people in the Netherlands added blades at right angles to the regular fan blades in order to speed up the rotation. When the windmill was taken to the American colonies, it was again modified into a smaller rotor at the top of a frame tower, with steel blades that were attached at an angle to catch more wind. Some were turned into the wind by hand, while others had wind vane attachments behind the rotors so they would turn automatically.

In 1898, Charles Brush, in Ohio, developed the first wind powered generator. It was composed of many large blades attached to a long vane to turn it away from the wind. Although this first attempt was unable to produce much electricity, it functioned for over 20 years and laid groundwork for today's aerodynamic turbines.

The first entry into kilowatt generation was built in Russia in the early 1930s, but it only worked for two years. Other European countries as well as the United States worked to perfect a high energy design, especially after World War II caused energy shortages. The new designs continued to include horizontal axes until the 1973 oil embargo, when some inventors returned to the vertical axis design in an attempt to produce the most aerodynamically sound device.

However, the vertical axis again proved to be unable to handle the large pressures required in the production of megawatts, the amount desired to make a substantial difference in energy costs. Beginning in the 1980s, a new type of horizontal axis wind turbine began to be developed. It had two or three blades and was placed on a tower framework; early versions had problems with acoustic resonance and were strongly disliked by people living nearby.

Finally, with European and American scientists working together, a design which consists of a one piece narrow tower and 3 blades was established and tested. Variations of this type of turbine are now in use across the United States including California, Texas, and the Midwest, as well as in countries such as India, China, Germany, Denmark, the Netherlands, and the U.K. At this time, the barrier to further use of wind power may be political in nature. However, two things are certain: non-renewable sources will continue to diminish over time, but the wind will always blow somewhere.

Sources:

IEA (International Energy Agency), Key World Energy Statistics, http://www.iea.org/textbase/nppdf/free/2010/key_stats_2010.pdf.

Telosnet, Illustrated History of Wind Power Development, http://telosnet.com/wind/index.html