WIND ENERGY

From the early beginnings of civilization man has used the power of wind to pump water and to grind grains, but, in relatively recent times, new technologies and the need to replace fossil fuels have given wind energy a new role.

A distinctive characteristic of wind energy is its deep dependence on four geographical factors: geographical location, local climate, altitude and terrain relief.  Coastal regions are especially apt for the use of wind energy due to the continuous movements of air masses caused by the thermal variations between the continents and the ocean.

The factors that make a region appropriate for the installation of wind energy systems are both the regularity of the wind and its speed.

The regularity of the movement of air masses allows a continuous energy generation.  Regarding wind velocity, there is a minimum speed dictated by the laws of physics.  The power of a wind turbine is a function of its area and the cube of the wind velocity. Historically, wind turbines have evolved from low speed, multiple blades models to high speed, three/four blades systems.

Classic windmills are used in rural regions, with wind velocities of 3 to 7 m/s (9 to 21 ft/s), to pump water and grind grain.

Fast wind turbines need wind velocities above 9m/s (27 ft/s), and they follow two basic designs: those with vertical axis and those with horizontal axis.

Traditionally, the most popular design has been the horizontal axis model,  but lately there have been new vertical axis models, displaying two distinct advantages:  they don’t need to be re-oriented,  and they have the generator in its base,  which makes them easier to maintain and reduces their need of strong support.

There are two concepts regarding wind energy installations.

The first relies on large machines, with blades as long as 100 m (300 feet). They have low production and maintenance costs, but require special materials capable of withstanding high stress.

The second concept is that of the “wind farm”, with a large number of small, low cost windmills, but with larger maintenance costs, due precisely to their number.

Wind energy technology is advancing fast, and new models and systems are continuously appearing in the market.