FREE ESSAY ON WIND POWER

WIND POWER

For many centuries wind has been used as a reliable source of energy. It is clean and
inexhaustible. Wind is used to make the job of a human simpliar. It is used for grinding
grain, pumping water, and to enable sail boats to move. Though often the amount of wind
power varies depending on the climate of an area. 
Although wind power is only used in selected areas the recent interest in fuel
conservation has sparked the development of windfarms. In the 1980's a studied showed
that in order to produce one kilowatt- hour of energy cost 4 cents. 
The best known horizontal axis machine in the United States is the American farm windmill
which is frequently used to pump water. This machine has rotor with up to 20 blades
mounted on a horizontal shaft and a tail-vane. A tail-vane is to keep the rotor facing
inot the wind by swiveling the machine. 
Unlike the farm windmill, the modern windmill only use four blades to generate
electricity and are able to operate at high rotor speeds. The Jacobs three blade
windmill, which was used widely between 1930 and 1960, could deliver about I kilowatt of
power at a typical wind speed of 14 miles per hour. 
Lately a different type of windmill has been used. It is a large horizontal two bladed
wind turbine. These were first installed in Ohio in 1975. Another type of windmill which
has a rotor diameter of 400 feet and a shaft height of 250 can produce 6,200 kilowatts of
power . These were first places in oahu, Hawaii.
The term "wind farm" is used for a large number of wind mills, that are clusters at a
site with a moderately constant wind, These are generally near mountain passes. With in
the united states wind farms appear in New Hampshire, California, and Hawaii. At these
sites the machine capacities range from 10 to 500 kilowatts. In 1984 the total energy
output of all the wind farms in the united states exceeded 150 million kilowatt-hours.