1. Natural Sciences and Technology Grade 6
Term 3: Energy and Change
Mains electricity
(ppt 7)

2. Topic 4 Mains electricity: Alternative energy
Wind Energy (Part 2) and Hydro Power
Natural Sciences and Technology - Grade 6

3. Disadvantages of wind power
You need a large number of wind turbines to power towns, as the largest turbine is able to produce electricity to sustain only +/- 500 homes.
Many people feel that wind turbines are unsightly (ugly) and that they should not disrupt the natural beauty of landscapes.
Natural Sciences and Technology - Grade 6

4. Wind power in South Africa
There is a wind farm near Cookhouse in the Eastern Cape.
There are many wind farms in the Western Cape that supply the national grid:
Klipheuwel, Hopefield, Gouda,
Perdekraal, Dassieklip, Darling, etc.
The wind farm at Klipheuwel is the
biggest wind farm in sub-Saharan Africa.
Natural Sciences and Technology - Grade 6

5. Natural Sciences and Technology - Grade 6
What is hydro power?
Hydro power is the process of changing the kinetic energy of flowing (or fast falling) water into electrical power that we can use.
Natural Sciences and Technology - Grade 6

6. What are the advantages of hydro power?
It does not produce pollution or waste.
It is a renewable and reliable energy source.
It is not expensive to maintain once the dam has been built.
The produced amount of hydro power can be increased or decreased whenever there is a high or low demand.
Water can be stored and be used in peak times.
Natural Sciences and Technology - Grade 6

7. Are there disadvantages?
It is expensive to build a dam.
It takes a lot of time to build a dam.
The dam will change the habitat and landscape upstream, as much more land will be submersed (under the water).
Silt can build up in the dam - as the water slows down. 
Natural Sciences and Technology - Grade 6

8. Hydro power in South Africa
There are many areas in the Eastern Cape and KwaZulu Natal regions that could be used as hydro electric plant sites.
Many of these plants would be under 100 mega watt, but all these together would ensure a greater sustainable future for South Africa.
We have a 1000 megawatt Pumped-Storage Facility in the Drakensberg.
Natural Sciences and Technology - Grade 6

9. Interesting information
Hydro power generation works well in mountainous countries as the water can be stored at high pressures.
The dam wall becomes wider at the
bottom, because the water pressure gets greater as the depth increases.
Natural Sciences and Technology - Grade 6