Understanding Wind Speed
Wind speed describes how fast the wind is moving and is measured in metres per second (m/s). It strongly influences how much electricity a wind turbine can produce.
How wind turbines respond to wind speed
- 3–5 m/s – Turbines start generating electricity (cut‑in speed).
- 10–15 m/s – Turbines operate at maximum output.
- ~25 m/s – Turbines shut down for safety (cut‑out speed).
Because wind varies constantly, turbines do not run at full power all the time. In real‑world conditions, only 10–40% of the wind’s energy is typically converted into electricity.
What is a good wind speed?
- < 5 m/s – Generally unsuitable for wind energy
- 6–7 m/s – Moderate, may suit small or specialised projects
- 7–8 m/s – Good for modern wind turbines
- > 8.5 m/s – Excellent wind energy conditions
Wind classes
Wind turbines are designed for different wind conditions, defined by International Electrotechnical Commission (IEC) standards:
- IEC III (Low wind): 7.5 m/s
- IEC II (Medium wind): 8.5 m/s
- IEC I (High wind): 10 m/s
Higher classes indicate stronger and more productive wind environments.
Understanding Wind Power Density
It combines wind speed, frequency, and air density into a single value and is measured in watts per square metre (W/m²). This makes it one of the best indicators of wind energy potential, often more informative than wind speed alone.
| Power Density (W/m²) |
Resource Quality |
| 0–200 |
Very poor |
| 200–300 |
Poor |
| 300–400 |
Marginal |
| 400–500 |
Good |
| 500–600 |
Very good |
| 600–800 |
Excellent |
| > 800 |
Outstanding |
