wind energy
HISTORY OF WIND POWER
Man has used wind energy in one form or another for thousands of years. Ships were first driven exclusively by the power
of the wind in their sails, lonf before other forms of power were devised. Windmills have an equally long history, and there
are references to them in the literature of ancient Babylon. The first 'modern' windmills were developed in the 19th century
for agricultural use in Australia and the United States.
With our increasing concern for the environment the interest in wind as an alternative, renewable and environmentally
friendly is ever increasing.
ABOUT THE WIND
Where Does The Wind Come From?
Pictures taken from "wind energy in theory" from Jens-Peter Molly and Verlag C.F. Müller Karlsruhe.
The air around us has a certain density. If the air didn't have any density gravity would not be able to attract it and it
would just float off into space ! There is only a very thin layer of air surrounding the earth - it extends upwards for
only 64km.
All the air around us is pushing down on us and the intensity of this pushing force is called air pressure or atmospheric
pressure.The pressure on the earth's surface due to the air above us is referred to as one atmosphere. The pressure of
the air on the earth's surface is measured by a barometer
wind power.
Wind is caused by the uneven heating of the earth. Wind turbines can capture
the solar energy stored in wind and convert it into electricity or use the
mechanical power directly. New technologies to generate electricity are very
cost competitive.
WIND POWER, THEORY:
INTRODUCTION
Wind is simply air in motion. It is caused by the uneven heating of the earth
by the sun. Solar heating varies with time and with the reflectance of the
surface.
OVERVIEW
Uneven heating of the Earth's surface causes the wind to blow. Many societies
have long taken advantage of this energy to travel great distances and perform
diverse tasks such as grinding, sawing and pumping water. Modern wind turbines
using advanced technologies are able to produce electricity for homes,
businesses, and even utilities. Wind power, already one of the most appealing
sources of energy today, will continue to prosper as new turbine designs
currently under development reduce the costs of wind power and make wind
turbines economically viable in more and more places.
The warming effect of the sun on the earth is greater at the equator than at the poles. Warmer air has less density than
colder air and rises above it, so the air pressure at the equator is less than at the poles. Air will always try to move to make
the pressure the same everywhere and so the warm air at the equator will try to move towards the poles and vice-versa.
This movement is another cause of WIND.
OFF-SHORE-WIND
The UK's off shore wind resource is very large. After allowance is made
for areas that may be excluded because of possible interference with shipping or fishing,
or because of unsuitable seabed conditions.
An investigation says that there is a potential of wind energy around the British Isles
at around 240TWh per year and suggested that more than half of this (134 TWh per year) was usable.
The wind has the characteristic to be stronger off-shore and less turbulent, but construction and
operating costs are considerably higher.
HOW DO WE MAKE ENERGY WITH THE WIND?
Any object that moves has kinetic energy. The movement of the air, or wind, means that it has this energy and it is this
energy that is used to turn the blades on the wind generator. The wind does not always move in the same direction
however, and it is necessary for the wind turbines and generators to be able move around to face the wind from whichever
direction it blows in.
The rotational energy of the revolving blades is transmitted either to a generator (of electricity) or to a machine for
mechanical work, such as a water pump. Electricity generating turbines may be connected to a range of applications, for
example, in the case of small turbines, to rechargeable batteries and in the case of larger turbines to a household or the
national grid.
Surprisingly, a significant problem wind turbine designers have is that often there can be too much energy in the wind. The
rotor blades can only convert a certain level of wind power into rotational power for the generator. If too much power is
converted the wind turbine becomes overloaded and has to be switched off. The maximum amount of energy
delivered each second is called the 'rated power' of the wind turbine.The next page is "Wind Power Components".
Wind Power Applications:
Grid Connected
A widely used application of wind turbines is for producing electric power
on-site at homes, farms, and businesses which are already served by a utility
grid. Because the average wind turbine generates electricity only 25 to 30
percent of the time, it may be important in areas where winds are seasonal or
where storage systems are not cost-effective to be connected to the electric
utility grid.
The Electric Power Research Institute (EPRI), a U.S. utility research
organization which sponsors a Utility Wind Interest Group to provide
member utilities with information about wind technology's progress, also
sees its economics as promising. In one summary of wind's advances, EPRI
declared, "Alone among the alternative energy technologies, windpower
offers utilities pollution-free electricity that is nearly
cost-competitive with today's conventional sources." Today, wind is
competitive with most conventional energy resources.
Aside from actual cost, wind energy offers other economic benefits which
make it even more competitive in the long term:
Greater fuel diversity and less dependence on fossil fuels, which are
often subject to rapid price fluctuations and supply problems.
This is a significant issue around the world today, with many
countries rushing to install gas-fired electric generating
capacity because of its low capital cost. As world gas demand
increases, the prospect of supply interruptions and fluctuations
will grow, making further reliance on it unwise and increasing
the value of diversity.
The next page is "Wind Power Applications".