Harnessing the wind
People have used wind power for thousands of years. Ancient Egyptians sailed the Nile using wind. Windmills in Persia ground grain more than 1000 years ago. Dutch windmills pumped water from low-lying land.
Today, wind power is one of the fastest-growing sources of electricity in the world. Modern wind turbines turn moving air into electricity.
Where wind energy comes from
Wind is actually a form of solar energy. The Sun heats Earth unevenly, creating differences in air pressure that make air move.
Parts of a wind turbine
| Part | Job |
|---|---|
| Blades | Catch the wind and spin; usually three, each up to 100 m long on large turbines |
| Hub | Connects the blades to the main shaft |
| Rotor | The blades and hub together |
| Nacelle | Box at the top holding the gearbox, generator and controls |
| Gearbox | Speeds up rotation for the generator (some turbines don’t need one) |
| Generator | Turns spinning motion into electricity |
| Yaw system | Turns the nacelle to face the wind |
| Anemometer and wind vane | Measure wind speed and direction |
| Tower | Lifts the turbine high, where winds are stronger |
How it works
- Wind pushes on the blades, which are shaped like airplane wings. Air flowing over them creates lift, making them spin.
- The spinning rotor turns a shaft.
- The shaft drives a generator that produces electricity.
- Cables carry electricity down the tower to the grid.
Most large turbines start generating at wind speeds of about 10–15 km/h and shut down in very strong winds (above about 90 km/h) to prevent damage.
Size matters
The power a turbine can capture increases with:
- blade length: doubling the blade length can roughly quadruple the power, because the swept area increases with the square of the length
- wind speed: doubling the wind speed increases power about eight times
That’s why turbines keep getting bigger and are placed on hills, coasts and open plains.
Wind farms
A wind farm is a group of turbines in one place. They can be:
- Onshore: on land, often on farms where crops and cattle can share the land
- Offshore wind: in lakes or the ocean, where winds are stronger and steadier
Wind power in Canada
Canada has thousands of wind turbines.
| Province | Notes |
|---|---|
| Ontario | Many wind farms near the Great Lakes |
| Quebec | Large wind farms along the Gaspé Peninsula |
| Alberta | Fast-growing wind industry in the windy south near Pincher Creek |
| Atlantic provinces | Strong coastal winds; PEI gets a large share of its electricity from wind |
Remote communities in Nunavut and the NWT are testing wind turbines to reduce their use of expensive diesel fuel.
Capacity factor
Wind doesn’t blow all the time. A turbine’s capacity factor compares what it actually produces with what it would make running at full power all the time.
| Source | Typical capacity factor |
|---|---|
| Onshore wind | About 30–40% |
| Offshore wind | About 40–50% |
| Solar | About 15–25% |
| Nuclear | Over 90% |
Combining wind with solar, hydro and storage helps keep power steady.
Advantages and disadvantages
| Advantages | Disadvantages |
|---|---|
| Renewable and free fuel | Wind is variable |
| No emissions while operating | Some people dislike the look or noise |
| Among the cheapest sources of new electricity | Can harm birds and bats if poorly placed |
| Land can still be farmed | Best wind sites may be far from cities |
| Quick to build | Blade recycling is a challenge |
Researchers reduce wildlife impacts by choosing sites carefully, studying migration routes, and slowing turbines at times when bats are most active.
Common mistakes
- Thinking turbines spin because they use electricity. The wind spins them.
- Thinking wind power only works on very windy days. Turbines run at moderate wind speeds.
- Thinking all turbines have gearboxes. Many modern ones use direct-drive generators.
Try it yourself
- Build a pinwheel. Test how fast it spins with different numbers of blades or blade angles.
- Use a fan and a small motor with a propeller to light an LED. Change the fan speed and record the brightness.
- Find a wind farm near you on a map. Why do you think it was built there?
Quick recap
- Wind turbines turn moving air into electricity.
- Blades spin a rotor that drives a generator in the nacelle.
- Longer blades and faster winds produce much more power.
- Wind farms can be onshore or offshore.
- Wind is renewable and low-cost but variable.