The idea of harnessing
the power of wind is not new. The first windmills
appeared in the early 12th century to mill grain and pump
water. At the beginning of the 20th century, over one million wind turbines were used to pump water and generate power. But it was not until the early 1970s that Québec
began to seriously consider wind as an energy source to produce
Wind results from the difference in barometric pressure between warm and cold air masses. The force of the wind drives the blades of the wind turbines, causing them to rotate. This movement is then transformed into mechanical energy, which, when coupled with a generator, produces electricity.
Wind energy worldwide
Wind energy is used as a source of electric power in over 90 countries worldwide. According to the Global Wind Energy Council, the total installed capacity of all wind farms around the world was over 432,883 MW at the end of 2015.
Distribution of installed wind energy capacity worldwide in 2015
Types of wind turbine
There are two types of wind turbine:
- Vertical axis wind turbines, in which the rotational axis is at right angles to the ground
- Horizontal axis wind turbines, in which the rotational axis is parallel to the ground and in line with the horizon. These turbines are the ones most commonly used today.
Vertical axis wind turbine
Horizontal axis wind turbine
Wind turbines require
- a minimum wind speed, generally 12 to 14 km/h, to begin to turn and produce low-level power;
- strong winds, from 50 to 60 km/h, to generate power at full capacity;
- winds below 90 km/h; over this speed, generation ceases to prevent equipment failure.
Large-scale, or commercial, wind turbines must be distinguished from domestic wind turbines.
Large-scale (commercial) wind turbines
These wind turbines have a tower between 70 and 138 metres high, and three blades forming a rotor up to 90 metres in diameter. Each turbine has a generating capacity of between 1 and 3 MW. Large-scale turbines are generally installed in groups, forming a wind farm that feeds electricity into the main power grid.
Some wind turbines with an output of more than 7.5 MW, which have been commercially produced since 2010, may (with the rotor) be more than 198 metres high.
Large capacity marine wind turbines (commercial)
A marine wind turbine, also called an offshore turbine, works in the same way as a land-based turbine, but is built in the sea to make better use of wind energy. These turbines are usually taller than their land-based counterparts and also have a greater electricity generating capacity, usually varying from 3 to 5 MW, although some may have a capacity of nearly 8 MW.
Domestic wind turbines
Domestic wind turbines are generally 8 to 12 metres high. They have between two and five blades, forming a rotor less than 4 metres in diameter, and generate a few kilowatts (kW) of power.
Domestic wind turbines give farms and homes located off the main power grid an independent source of energy that can be used to meet some of their heating needs or to power small electrical devices. This is known as self-generation. The power generated can be combined with other forms of energy, such as solar power or electricity from a diesel generator. The capacity of each system is limited to 50 kW, and the rules governing the location, height and set-back distances of self-generation systems are set by the local municipality or regional county municipality.