What is wind?
Or, thinking about it, perhaps we have gone too fast and skipped a key question: where does wind come from?
It is something so common that we don’t even ask ourselves how it is generated. Greek mythology attributed wind control to Aeolus, keeper of the winds, but science tells us that it is caused by the effects of the Sun on the Earth.
Between 1% and 2% of solar radiation absorbed by the planet ends up as wind. This is because the earth’s crust transfers a large amount of solar energy into the air, causing this to heat up, become less dense and expand. At the same time, cooler and heavier air -from the seas, rivers and oceans- starts moving to take the place left by the warm air.
Wind is simply air in motion. Air masses moving from high-atmospheric areas to other lower pressure areas at speeds proportional to the pressure differences between the two areas (the greater the difference, the more the wind blows).
Where to install a wind farm?
In general terms, air turbines are normally located in coastal areas. This is because of the amount of thermal currents generated between land and water. They are also often installed on continental plains and mountainous areas, which tend to be high-wind areas.
But one thing is flying a kite, and another is generating energy. For the latter, we need winds blowing between 10-14 km/h and 90 km/h. If we fall short on most days (or we exceed these), this is not the right place for a wind farm.
There are also a series of essential requirements in order to install a park:
- Over 2,000 hours of wind per year (equivalent to 83 days of non-stop wind).
- It is essential to respect the fauna in the area, establishing a clearance area for birds to pass between the air turbines.
- The nearest urban centre must be more than 1 km away, to avoid acoustic pollution.
- The installation of wind parks on land protected from development is prohibited.
- The wind park cannot interfere with the surrounding electromagnetic signals, since television, radio or telephone lines could be affected.
From the heavens to your house
The wind blows, the windmill blades spin at full speed… and you have clean and pure electricity. But, how does it get to your home?
This process begins with a transformer that increases that electricity by more than four times its original, to then send it via overhead lines to a power substation, where the power is once again increased.
Now all that energy simply has to be sent to your home via the conventional power grid.
The future of wind energy
Despite its widespread installation, wind energy is still a source in development. Onshore wind power is still the most well-known, but it is important to remember that the earth’s oceans are so much bigger than the land area.
In recent years, offshore or marine wind power has been developed: windmill platforms out at sea.
These facilities have a promising future. They have a longer useful life than onshore ones and they end up producing more energy since wind speeds out at sea are more constant.