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 50 countries worldwide. According to the Global Wind Energy Council, the total installed capacity of all wind farms around the world was over 120,798 MW at the end of 2008.
Distribution of installed wind energy capacity worldwide in 2008
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 80 and 100 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.
Wind Turbines of 5 MW, in production on experimental basis, can reach more than 100 metres high.
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.
Small Wind and You