20-07-2012, 02:02 PM
WIND POWER
wind power.docx (Size: 1.6 MB / Downloads: 143)
INTRODUCTION
The quest of renewable energies that preserves the environment is an issue of major importance. Wind energy is one typical example among many others. The aerodynamic characteristics of wind turbines are closely related to the geometry of their blades. The innovation and the technological development of wind turbine blades can be centred on two tendencies. The first is to improve the shape of the existing blades, in order to achieve an optimal circulation. The second is to design new shapes of blades in order to get some more ambitious aerodynamic characteristics.
The aim is to give an overview of the history of wind power, an update on modern utilization of wind power. During the recent years the history of wind power has been the object for many studies.
THE HISTORY OF WIND POWER
The technology of transforming the kinetic energy of the wind into useful mechanical power has been applied by man since antiquity. Wind energy is, together with energy from streaming water utilized by a water wheel, the oldest source of power applied by mankind, but we have only solid historical evidence that the energy of wind has been utilized this way for at least one thousand years.
The use of wind power is said to have its origin in the Asian civilizations of China, Tibet, India, Afghanistan, and Persia. The first written evidence for the use of wind turbines are that of Hero of Alexandria, who in the third or second century BC described a simple horizontal-axis wind turbine. It was described as giving power to an organ, but it has been discussed whether it was of any practical use apart from being a kind of toy. From more solid evidence we know that in the 7th century B.C. the Persians seriously used wind power from a vertical-axis machine.
From Asia the use of wind power spread to Europe through civilization. From contemporary sources we know that windmills have been used in the 11th or 12th century in England. Also from a contemporary eyewitness (1190) we know that German crusaders brought the skills of building windmills to Syria. From this, we may assume that this technology was generally known all over Europe since the Middle Ages.
APPLICATIONS OF WIND POWER
Historically, the power from wind turbines historically has been used as a direct shaft power. The rotor axle was directly connected (though, through a gearing ratio) to the mill stone at the old windmills.
Today the output power from wind turbines can be utilized in two ways. Either by direct use of the mechanical shaft power (through a gearing ratio, though) or by letting the wind turbine power an electrical generator, and then utilize the power as electrical power.
Traditionally only the mechanical shaft power was available. During the 18'th and 19'th century windmills all over Europe and the New World were giving power to all sorts of farming and light industrial processes. Windmill-powered machines such as grinding mills, water pumps, threshing machines, saw mills, sugar cane refineries, etc. Today wind turbines are widely used for water pumping all over the world.
One problem by using the mechanical shaft power is of course that the wind turbine has to be close to the place of the machine used. By letting the wind turbine drive an electrical generator one can transfer the power over quite a large distance to the final utilization. Then the electricity can give power to an electrical motor, which gives power to the all the above mentioned classical applications.
Wind energy
Winds are caused because of two factors.
1. The absorption of solar energy on the earth’s surface and in the atmosphere.
2. The rotation of the earth about its axis and its motion around the Sun.
A wind mill converts the kinetic energy of moving air into Mechanical energy that can be either used directly to run the Machine or to run the generator to produce electricity. Because of these factors, alternate heating and cooling cycles occur, differences in pressure are obtained, and the air is caused to move. The potential of Wind energy as a source of power is large. This can be judged from the fact that energy available in the wind over the earth’s surface is estimated to be 1.6x107 K.W besides the energy available is free and clean.
Advantages of Wind energy
(1) The wind energy is free, inexhaustible and does not need transportation.
(2) Wind mills will be highly desirable and economical to the rural areas which are far from existing grids.
(3) Wind power can be used in combination with hydroelectric plants. Such that the water level in the reservoir can be maintained for longer periods.
Disadvantage of Wind energy
(1) Wind power is not consistent and steady, which makes the complications in designing the whole plant.
(2) The wind is a very hazard one. Special and costly designs and controls are always required.
(3) The cost factor, which has restricted the development of wind power in large scale for feeding to the existing grid.
(4) It has low power coefficient.
(5) Careful survey is necessary for plant location.
wind power.docx (Size: 1.6 MB / Downloads: 143)
INTRODUCTION
The quest of renewable energies that preserves the environment is an issue of major importance. Wind energy is one typical example among many others. The aerodynamic characteristics of wind turbines are closely related to the geometry of their blades. The innovation and the technological development of wind turbine blades can be centred on two tendencies. The first is to improve the shape of the existing blades, in order to achieve an optimal circulation. The second is to design new shapes of blades in order to get some more ambitious aerodynamic characteristics.
The aim is to give an overview of the history of wind power, an update on modern utilization of wind power. During the recent years the history of wind power has been the object for many studies.
THE HISTORY OF WIND POWER
The technology of transforming the kinetic energy of the wind into useful mechanical power has been applied by man since antiquity. Wind energy is, together with energy from streaming water utilized by a water wheel, the oldest source of power applied by mankind, but we have only solid historical evidence that the energy of wind has been utilized this way for at least one thousand years.
The use of wind power is said to have its origin in the Asian civilizations of China, Tibet, India, Afghanistan, and Persia. The first written evidence for the use of wind turbines are that of Hero of Alexandria, who in the third or second century BC described a simple horizontal-axis wind turbine. It was described as giving power to an organ, but it has been discussed whether it was of any practical use apart from being a kind of toy. From more solid evidence we know that in the 7th century B.C. the Persians seriously used wind power from a vertical-axis machine.
From Asia the use of wind power spread to Europe through civilization. From contemporary sources we know that windmills have been used in the 11th or 12th century in England. Also from a contemporary eyewitness (1190) we know that German crusaders brought the skills of building windmills to Syria. From this, we may assume that this technology was generally known all over Europe since the Middle Ages.
APPLICATIONS OF WIND POWER
Historically, the power from wind turbines historically has been used as a direct shaft power. The rotor axle was directly connected (though, through a gearing ratio) to the mill stone at the old windmills.
Today the output power from wind turbines can be utilized in two ways. Either by direct use of the mechanical shaft power (through a gearing ratio, though) or by letting the wind turbine power an electrical generator, and then utilize the power as electrical power.
Traditionally only the mechanical shaft power was available. During the 18'th and 19'th century windmills all over Europe and the New World were giving power to all sorts of farming and light industrial processes. Windmill-powered machines such as grinding mills, water pumps, threshing machines, saw mills, sugar cane refineries, etc. Today wind turbines are widely used for water pumping all over the world.
One problem by using the mechanical shaft power is of course that the wind turbine has to be close to the place of the machine used. By letting the wind turbine drive an electrical generator one can transfer the power over quite a large distance to the final utilization. Then the electricity can give power to an electrical motor, which gives power to the all the above mentioned classical applications.
Wind energy
Winds are caused because of two factors.
1. The absorption of solar energy on the earth’s surface and in the atmosphere.
2. The rotation of the earth about its axis and its motion around the Sun.
A wind mill converts the kinetic energy of moving air into Mechanical energy that can be either used directly to run the Machine or to run the generator to produce electricity. Because of these factors, alternate heating and cooling cycles occur, differences in pressure are obtained, and the air is caused to move. The potential of Wind energy as a source of power is large. This can be judged from the fact that energy available in the wind over the earth’s surface is estimated to be 1.6x107 K.W besides the energy available is free and clean.
Advantages of Wind energy
(1) The wind energy is free, inexhaustible and does not need transportation.
(2) Wind mills will be highly desirable and economical to the rural areas which are far from existing grids.
(3) Wind power can be used in combination with hydroelectric plants. Such that the water level in the reservoir can be maintained for longer periods.
Disadvantage of Wind energy
(1) Wind power is not consistent and steady, which makes the complications in designing the whole plant.
(2) The wind is a very hazard one. Special and costly designs and controls are always required.
(3) The cost factor, which has restricted the development of wind power in large scale for feeding to the existing grid.
(4) It has low power coefficient.
(5) Careful survey is necessary for plant location.