Why is wind a feasible renewable energy option in South Africa?

Large parts of South Africa’s coastal land, as well as various areas inland, have an economically viable source of wind energy. Furthermore, the scale and maturity of the global wind industry have made it a cost-competitive energy option, compared not just to other renewable technologies but also many fuel-based technologies.

Also with significant local content, these technologies can also raise the employment intensity of the electricity generation sector.

How many wind turbines are sited at Jeffreys Bay Wind Farm?

The project comprises of 60 wind turbines.

How big are the wind turbines?

The height and weight statistics of the wind turbines are:

  • a hub height of 80 meters
  • a blade length of 49,5 meters
  • a rotor diameter of 101 metres
  • the rotor weighs 60 tones
  • the nacelle weighs 82 tones
  • the tubular steel tower weighs 162 tones

How do wind turbines operate?

Wind turbines are sophisticated machines with computer controls.
A typical operating sequence is as follows:

  • when the wind speed reaches the cut-in speed of the turbine (usually around 4 metres per second), the turbine blades will spin up to operating speed, usually around 14 to 29 rpm (varies by turbine model), and start generating electricity
  • as the wind speed increases, the generator output increases
  • when the wind speed increases to the rated wind speed (usually around 12-13 metres per second), the generator will output its nameplate-rated capacity (i.e. a 750-kW turbine would now output 750 kW)
  • as the wind speed continues to increase, the generator output will remain at the rated capacity (i.e. 750 kW) until the wind reaches the cut-out speed (usually around 25 metres per second)
  • at this wind speed, the turbine will deploy its tip-brakes and then apply its disk brake, stopping the blades in a few revolutions
  • it will then rotate itself 90 degrees out of the wind and park itself
  • if the wind speed drops to a level below the cut-out speed for a sufficient length of time, the turbine will point itself back into the wind, release the brake, and resume power production.

What happens when the wind doesn’t blow?

By its very nature, wind varies and does not blow consistently all the time. This is why, where the wind turbines are sited is so important; erecting them in an area with prevailing winds ensures that the turbines can generate energy and provide energy to the grid about 90% of the time.

The wind turbine only cuts in (starts operating) when wind speed reaches approximately 13km/h.

Are wind turbines noisy?

Modern wind turbines are not considered noisy; the mechanical (gearbox/ generator) noise and vibration is almost undetectable with the main sound being the aerodynamic swish of the blades passing the turbine tower.

Animals and livestock ignore wind turbines, and continue to graze as they did before wind turbines were installed.

Do wind turbines kill birds?

In answer to the concern that wind turbines kill birds, studies show that birds are seldom bothered by wind turbines and in fact, the number of birds killed by wind turbines is negligible compared to the number that die as a result of other human activities.

Studies from the western part of Denmark, show that birds – by day and night – tend to change their flight route some 100 – 200 metres before the turbine and pass above the turbine at a safe distance.

Bird studies form an integral part of the Environment Impact study and any adverse affects will be highlighted during this stage of the development.

See Denmark Bird Study here.

What happens if turbine throws a blade or a tower collapses, maybe on neighbour’s property or a power line?

When designing the site layout, our team ensured that turbines are located with ample clearance from the border of the property, main roads and power lines so that, in the highly unlikely event that a tower collapses, it will not traverse the border of the property.

Can wind farms affect airport and military radars?

Jeffreys Bay Wind Farm doesn’t fall within the ‘radar buffer distance’ and therefore can’t affect any airport or military radars.

What about neighbourhood/community acceptance?

The Environmental Impact Assessment included a comprehensive stakeholder consultation process as a prerequisite.

This process included: community involvement, information evenings, and open communication with all local stakeholders and this played a vital role in achieving neighbour/ community acceptance of a project.

Any objections/ queries from neighbours were made and assessed by the planning and environmental authorities via their standard process.

Our team engaged early on in the project with all local residents and local communities to ensure they are informed and consulted throughout the development, construction and operation stages.

Some people say wind farms are unsightly and create a blot on the landscape?

Research has shown that just as many people like the appearance of wind turbines as dislike them.

What is involved in decommissioning a wind farm?

Jeffreys Bay Wind Farm has a 20 year lease agreement with Eskom, should the project then need to be decommissioned, it will be done in accordance with the environmental authority’s stipulations.

Typically they will require all visible traces of the wind farm to be removed. This takes care of the turbines. Access roads can be removed, although it may be best to leave them for public or private usage.  The concrete bases can also be removed, but it is often better to leave them under the ground, as this causes fewer disturbances. If the turbine bases are left they would be covered with stone or other indigenous material, and the site returned as closely as practicable to its original state. Wind energy technology is essentially reversible, and compared to the problems associated with decommissioning a nuclear power station, or a coal or gas fired plant, decommissioning a wind farm is straight forward and simple.

How safe is wind energy?

Wind energy is one of the safest energy technologies during the normal operation of the wind turbine.

Monday 17/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Tuesday 18/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Wednesday 19/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Thursday 20/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Friday 21/02/2014

  • 3 loads (incl. 3 blades) via route N2
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Majority shareholder, Globeleq is jointly managing the construction of Jeffreys Bay Wind Farm and will play a key role as the management company during operations.