Wind turbines are large devices that convert kinetic energy from the wind into mechanical energy, thereby creating wind power. This kinetic energy is also known as wind energy, and it presents one of the most viable alternatives to traditional coal-generated power in South Africa.
Most horizontal-axis wind turbines (HAWTs) are made up of two or three blade-like propellers called the rotor, which are attached to the top of a very tall tower. As the wind blows, the rotor spins, and the turbine begins to generate electricity. Wind needs to reach a particular speed before the propellers begin to spin – usually 4m per second.
Wind turbines are computer operated and thus work in a highly sophisticated manner.
Image source: HowStuffWorks.com
As wind intensity increases, so does the output of the generator – but once wind reaches a certain speed (roughly 25 meters per second), the device applies a powerful set of brakes that stop the propellers’ revolutions. It then moves itself out of the stream of wind, turning at a right angle to the direction of the wind. Once the wind speed decreases sufficiently, the propellers will start up again – and so the cycle continues.
Wind turbine size, output capacity & applications
Wind turbines are very large structures that can reach upwards of 80m in height. The average blade length of a 2.3MW wind turbine is 45m, and a single wind turbine of this size can sweep an area of almost 7000m. This means that a significant amount of land is required for the establishment of a wind farm – preferably in outlying areas where the turbines won’t interfere with day-to-day activities. For this reason, the majority of wind farms are erected on farmlands in rural areas or offshore where their impact is likely to have little effect on regular activities. Depending on the size of a particular wind turbine, its output capacity will range from roughly 1.5MW to 3.5MW. Annually, a single commercial wind turbine can produce enough electricity to power more than 1,000 households, and generates more than 4.5-million units of electricity.
Smaller wind turbines, meanwhile, can be used for a variety of private and public applications, including on and off-grid residential use, rural schools and clinics, offshore platforms and telecoms towers, and any other applications where electricity supply may be unstable or unreliable, or absent altogether. Wind energy is a free, safe and clean source of energy, and it thus poses little or no risk to surrounding communities. Although birds have been reported to fly into the propellers, the incidence of this type of occurrence remains low.
Wind turbines for sustainable, renewable energy
Wind turbines are designed to take advantage of strong, consistent winds, and to provide energy to the electricity grid roughly 90% of the time. This makes wind turbines a highly effective source of energy, particularly in a country that is known for its prevailing winds.