Wind energy

Small wind turbines are best suited to rural businesses with no connection to the electricity network, and which get strong, consistent wind.

How wind turbines work

Wind turns the rotor blades of a turbine. The turbine then spins a shaft connected to a generator where electricity is generated. Wind turbines generate electricity as long as there is relatively constant wind at a reasonable speed. Most small wind turbines need an average speed of 4.5 metres per second (16 km/h).

Micro and small scale wind turbines are usually mounted on towers so they’re exposed to more consistent wind with a higher average speed. Because wind blows intermittently, small wind turbines are usually combined with other energy generators in a grid-connected or stand-alone power system. Further information on consumer-scale wind turbine systems is available from ENERGYWISE.

Grid-connected systems - ENERGYWISE website

Stand alone power systems (SAPS) - ENERGYWISE website

Types of wind turbine

Horizontal-axis turbines

Most wind turbines are horizontal-axis turbines - like the ones you see on wind farms. The turbines are mounted on a tower facing the wind. Small-scale versions have tail fins to make sure the blades constantly turn towards the wind.

Vertical-axis turbines

Vertical-axis turbines are less common than horizontal-axis turbines, but have the advantage of not needing to face the wind. This is useful where the wind direction varies quickly. Some are small enough to be mounted directly onto a building, others are mounted on a pole in the ground.

Rooftop or wall-mounted turbines

Micro wind turbines can also be rooftop or wall-mounted.

Best sites for small wind turbines

In urban areas - even on roof tops - turbines aren’t usually very successful. Winds tend to be turbulent, weak, and erratic because of obstructions such as buildings and trees.

If your business is in a rural area that is exposed to strong and consistent wind, and there is no connection to the electricity network, then it may be cost effective for you to install a small scale wind turbine.

Energy output of small wind turbines

The amount of electricity a wind turbine generates depends on the wind speed and the turbine's capacity rating. If a model has a rated capacity of 1 kW, it will produce 1kWh of electricity per hour when exposed to a specific rated wind speed. This specific rated wind speed varies between different models and manufacturers, but is generally 11 to 15 metres per second. This is about 40 to 55 kilometres per hour.

Capacity ratings

In the real world a turbine will not be exposed to ideal conditions or the rated wind speed at all times. This means turbines will usually generate only 10 to 40% of their rated capacity every hour.

To calculate how much electricity a turbine will generate in a day, multiply the rated capacity by 24 hours, then multiply it again by percentages ranging from 10 to 40:

  • a 1 kW wind turbine might generate between 2.4 kWh and 9.6 kWh a day (1 x 24 hours x 10% = 2.4 kWh/day, 1 x 24 hours x 40% = 9.6 kWh/day).

Maintenance of wind turbines

Small wind turbines generally need more ongoing maintenance than solar panels and micro-hydro systems. This is especially true if your turbine is on a very exposed site.