Every 24 hours, wind generates enough kinetic energy to produce roughly 35 times more electricity than humanity uses each day. – Rebecca J. Barthelmie and Sara C. Pryor, tedEd.com
In 2019, 52% of renewable energy was generated through the harnessing of the wind. South Africa is not only blessed with a fantastic climate for solar power generation, but wind generation is also an excellent resource. This is proven by some of the lowest wind energy tariffs in the world. Let’s take a look at what wind generation is and how it works.
What is wind energy?
Wind power or wind energy describes the process by which the wind is used to generate mechanical power or electricity. Wind energy is generated when the kinetic energy of the wind is harnessed by wind turbines – those huge propellers looking like aeroplane propellers on top of a long pole – and converted into mechanical energy. To generate electricity, this mechanical energy is used to rotate a generator situated in the hub of each turbine.
The basic principle of generating energy through the means of wind is simple. A series of sales, or blades, are mounted around a router that catches the wind, converting its kinetic energy into rotational or mechanical energy. In the olden days, we used traditional windmills like this to grind wheat or pump water. In modern wind turbines, it turns a generator that creates electricity.
3 primary factors determine exactly how much energy these turbines can produce:
- The size and orientation of the blades
Wind turbines can be designed with their blades on a vertical or horizontal axis. Vertical blades can pick up wind coming from any direction, but with much less efficiency than horizontal axis rotaries. The horizontal axis allows the blades to capture the wind full force by tracking the wind’s direction and turning to face it. Wind sensors and computer systems automatically adjust the blades with expert precision to capture as much energy as possible.
- The blades’ aerodynamic design
The blades themselves need to be shaped to maximise efficiency. Wind travels faster over a curved surface, creating a low-pressure pocket above the blade that forces it upwards. Since the amount of lift depends upon the angle at which the wind is moving relative to the blade, modern blades also incorporate a twist, optimising how much of the blade can cut into the wind. The blades are made from fibreglass and resin layers, making it possible for them to operate through rain, lightning and blistering sunlight for over 20 years.
- The amount of wind turning the rotary
A wind turbine can only capture wind if it’s in a windy environment. Wind speeds typically increase the higher into the atmosphere you travel. Therefore, most turbines are over 100 meters tall with equally large rotary diameters. A turbine of this size can capture an enormous amount of wind, generating enough electricity every year to power 750 South African homes.
A wind farm of approximately 200 turbines could power over 150 000 homes for an entire year. – Rebecca J. Barthelmie and Sara C. Pryor, tedEd.com
- Wind power is the cheapest form of renewable energy. Currently, wind power will cost the consumer R0,62/kWh and the price of wind energy will probably continue to decline, driven primarily by technical advancements and mass production.
- Even though wind farms take up a huge amount of space, most of the land around the turbines remains usable. Wind farms can be built on or near agricultural farms without disrupting crop production.
- The only danger from wind turbines is if it collapses and causes damage, but these turbines are installed in a way that makes them more stable than some trees.
- Wind is a less predictable resource than fossil fuels. We call this intermittency, a disruption caused by the inconsistency of the wind itself. The wind blows at various speeds, making it hard to predict the amount of energy it can collect at a given time. The result is that suppliers and cities need to have an energy reserve or alternative sources of power in case the winds die down for longer lengths of time.
- Turbines could be detrimental to bird and bat populations. The blades can hurt or kill these species that fly into them. The noise pollutions generated from whirring blades may also affect wildlife on the ground.
- Wind turbines can be very loud, causing noise pollution. This means that building them in residential areas is difficult. Additionally, because wind turbines need to be built up high enough to capture a good amount of wind, the turbines can often interrupt otherwise scenic landscapes, such as mountain ranges, lakes, oceans, and more.