Wind power energy sytem

Wind is invisible yet it contains an enormous amount of energy. The sun radiates 100,000,000,000,000 kilowatts of energy per hour which is picked up by the Earth. Of this amount, one to two percent is converted into wind energy. However, only an infinitesimally small amount of this wind energy is harnessed by people for their energy needs.

Because water is cooler than the adjacent land masses during the daylight area, the seashore is an important source for wind energy. The air in the warmer land areas rise causing a low pressure at ground level which pulls in the cooler air from the sea. At night this wind direction will often reverse because the water will radiate more heat that has been absorbed during the day than the adjacent land areas.

Because of the great abundance of wind energy, people have been using it as a source of power for thousands of years. It is believed that the first use of the wind as a source of power dates back to about 3000 B.C. when people learned how to move a small boat by making sails from tree bark or animal skins. The bark or skins caught the wind and pushed the sailboat along. Later, Arab sailors improved upon the sailboat design by using a triangular sail called a lateen. These triangular sails of the lateen design are still used today.

Using the basic sail design, the Persians developed the first windmills to grind grain around 200 B.C. These early windmills had sails made from bundles of reeds which caught the wind and turned an upright pole connected to a grindstone. This type of windmill was later redesigned with sails that turned like a propeller on an airplane. This latter type of windmill can still be seen on several of the Greek islands where they continue to be in use.

Windmill technology took a big leap in Holland around 1400 A.D. with the invention of the tower mill. Tower mills had a fixed tower but the propeller sails were attached to a movable top section that could be turned into the wind. This was in contrast to the earlier design where the propeller was stationary. The tower mills were further improved in 1745 by British inventor Edmund Lee who made a fantail, a miniature windmill, that moved the top section of the tower mill until the main sails faced the wind whenever the wind shifted.

Windmills for several centuries were the main source of power for many important tasks such as pumping water, sawing wood, grinding grain, and making paper. However, following the development of steam and diesel engines during the Industrial Revolution, windmills were used less and less as a source of energy. For example, there were around 12,000 windmills in use in Holland in 1800 but by 1960 less than 1000 windmills in that country were in use.

With the rising concern of polluting or dangerous sources of energy such as coal or nuclear power, there is a renewed interest in recent years in tapping the wind as a source of power. Another concern is power shortages such as the ones that have occurred in California.

Advanced windmills which are used to generate electricity are called wind turbines. Although we think of the wind turbine as a fairly recent development, wind turbines have been used for over a century with the first one built to generate electricity in Cleveland, Ohio in 1888. This early turbine was able to generate only 12 kilowatts (compared to over 100 kilowatts generated by modern wind turbines) and was discontinued after 20 years in operation.

Later improvements in the propeller design increased the amount of kilowatts generated by the wind turbines. Following WWI, wind turbines produced double the kilowatts of the first wind turbine in Cleveland and were used extensively in Denmark as a source of power. By the mid 1920s wind turbines were also widely used in the Great Plains region of the U.S.A. because of the difficulty of providing electricity to remote farms and because this was a windy area. However, following extensive rural electrification programs of the 1930s, the use of wind turbines in the farm areas of the U.S.A. declined greatly.

When interest in non-polluting sources of energy grew in the 1970s, Danish and German designed wind turbines became important due to their aerodynamic designs which harnessed wind power in an efficient way. These improved designs were used when California vastly expanded its wind farms between 1981 and 1990.

Most of the wind energy in the world today is harnessed in these California wind farms, located near Tehachapi and Palm Springs. Over 17,000 wind turbines in California now generate enough electricity to supply power to a city of 300,000 population.

Improved wind turbine technology is making it possible to produce even more efficient wind turbines, which comes at an opportune time. Wind power energy systems are increasingly important as they do not pollute and utitilize a renewable resource.