Wind Energy
Wind is a form of solar energy. The irregular heating Earth's atmosphere by the Sun causes the air mass to move from regions of high pressure to lower pressure areas. The kinetic energy of the moving air (wind energy) can be translated directly into mechanical or electrical energy.
Historically, the first use of wind energy was probably to propel boats by use of sails. There is some evidence that wind energy was being used this way as early as 5000 B.C. on the Nile. At some point later, this linear motion was translated into rotational motion by means of the windmill. These were in existence in China several centuries before Christ. Windmills were initially used to pump water but over the centuries they have been used to grind grain into flour and to produce electricity. They are found in all parts of the world with Holland and Spain historically being most associated with their use.
Today much attention is being paid to wind energy as an alternative to conventional methods of producing electrical energy. The advantages of using the wind as a means of electrical energy production are obvious. In these days of atmospheric pollution it is an attractive proposition to have absolutely clean, non-polluting energy sources such as wind energy. In 1990, California produced enough electrical energy from the wind to offset the emission of 2.5 billion pounds of carbon dioxide from conventional power plants.
The basic technology has been in use since the beginning of the twentieth century. The energy of the wind is used to turn windmill blades that rotate a generator to produce electricity. Modern windmills have reached high levels of efficiency by using the latest advances in electronics, material technology and aerodynamics. The most recent designs have reached levels of up to 98% efficiency. However, all this comes with a price tag. Roughly 80% of the cost of electrical conversion from wind energy is the price of equipment. Once installed, however, the running costs are low, as no energy sources such as oil and coal are needed.
Obviously, wind energy can only be used if there are fairly predictable winds with enough speed to be efficient. Several areas of the United States (Appalachia, the Plains and the Pacific Northwest) do have very good wind levels. It has been estimated that North Dakota alone could produce 36% of the energy needs of the lower 48 states from the wind it receives. This, of course, would not be a practical proposition. Hawaii has good wind supply and currently boasts some of the largest windmills in the world. The largest have blades up to 100 yd (91 m) in length and stand twenty stories high. Each one can meet the energy requirements of 1,400 homes.
There are certain disadvantages to wind energy. Obviously it can be uncertain and uncontrollable in its delivery. Storage of electricity is difficult but necessary if the wind is going to drop off. Large windmills can be unsightly and noisy. In addition large numbers of bird kills have been recorded over the past few years. Also the price tag is still an issue, although with rising conventional energy cost wind energy is looking a better proposition. It does look as though wind energy has a future as one of the world's energy sources. The U.S. Department of Energy recently announced an initiative to have 5% of the nation's energy being wind generated by 2020.
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