Wind power
Eolic power, or wind power, as its name suggests is the power obtained from the wind, in other words, the power obtained from the kinetic energy generated by the effect of air currents and by the vibrations produced by the air. The term "eolic power" comes from the Latin Aeolicus, meaning belonging to or relating to Eolo, the god of wind in Greek mythology and, therefore belongs to or relates to wind. Wind power has been harnessed since ancient times in order to move boats with sails or to make milling machinery work with the movement of their blades. It is a renewable or green energy, which produces no CO2 atmospheric emissions
Wind power is associated with the movement of air masses which travel from areas of high pressure to adjacent areas of low pressure with speeds proportionate to the pressure gradient.
Wind is generated by the non-uniform heating of the earth’s surface by solar radiation, between 1 and 2% of the energy from the sun is converted into wind. During the day, the air masses above oceans, seas or lakes stay cool in relation to the neighbouring areas located above continental masses.
The continents absorb less sunlight and the air above the land expands, becomes lighter and rises. The colder and heavier air that comes from the seas, oceans and large lakes moves in to take the place left by the hot air.
In order to harness wind power, it is important to know about seasonal, daytime and night time variations of winds, speed variations in relation to height above the ground, gusts of wind over short periods of time, and the maximum values reached with past data spanning at least 20 years. It is also important to know the maximum wind speed. In order to use wind power, the wind speed needs to be a minimum of 12 km/h and must not exceed a maximum of 65 km/h.
Wind power is harnessed using wind machines (or windmills) capable of transforming the wind power into mechanical rotation power which can be used either to directly operate the milling machines, or to produce electricity. In the case of the latter, the conversion system, (which comprises an electrical generator with its control and grid-connection systems) is known as a wind turbine.
Wind power’s low energy density per surface module results in the need to install a larger number of machines in order to harness the available resources. The most typical example of a wind installation is a “wind farm" (various wind turbines installed in an area and connected to one single line which connects to the local or national grid).
Currently, wind energy is mostly used to move wind turbines. On these machines, the wind power moves a blade and by means of a mechanical system rotates the rotor of a generator, normally an alternator, to produce electricity. In order for the installation to be profitable, they are usually grouped together in what are commonly known as wind farms.
Although wind farms are relatively recent inventions which became popular in the 1980-90's, wind power has long been used for other applications such as milling grain or pumping water.
