The wind extractors. Fundamentals and evolution of wind energy

The wind extractors

The wind ventilation system is a mechanical ventilation system that operates by using wind extractors that work with the energy of the wind thanks to the effect of the temperature differential existing between the outside and inside of a cover. In this way, a continuous process of ventilation is obtained in which the wind extractor sucks out the hot air accumulated under the cover to the outside. This volume of extracted air is naturally compensated by the entry of cooler air through the windows located on the lower levels of the building. The circulation of air ensures good ventilation inside the rooms, facilitating the removal of pollutants, humidity, or the vapor accumulated inside.

Wind energy. Fundamentals and evolution

Wind energy is a kinetic energy obtained from the air currents generated in the atmosphere as a result of the irregular heating of the Earth's surface. Thus, between 1% and 2% of the energy from the Sun is transformed into wind. During the day, continents transfer a greater amount of solar energy to the air than bodies of water, causing the air to heat up and expand. This air has become less dense and therefore rises. The colder and heavier air that comes from the seas, oceans, and large lakes moves to occupy the space left by the warm air.

As complex as this process may seem, the obtaining of wind energy is nothing new. On the contrary, wind as a driving force has been used since ancient times. It has moved the sails that propelled ships and made the machinery of windmills work by moving their blades. The first were built in Sistán (Afghanistan) in the 7th century. They were vertical-axis mills with rectangular blades. The first windmills appeared in Europe in the 12th century in France and England, and from there they spread to the rest of the continent. They were wooden structures known as windmill towers, which were manually rotated around a central post to extend their blades to the wind. The tower mill was developed in France throughout the 14th century. It consisted of a stone tower crowned by a rotating wooden structure that supported the axis of the mill and the machinery located at its top. These early prototypes had a series of common characteristics: a horizontal axis protruding from the top of the mill from which between four and eight blades extended, reaching lengths of up to nine meters. The energy generated by the rotation of the axis was transmitted through a gear system to the machinery of the mill located at its bottom.

Currently, wind energy is mainly used to obtain electricity through wind turbines. Within them, wind energy moves a rotor, and through a mechanical system, it turns the rotor of a generator that produces electrical energy.