I personally would choose the hydroelectric power plant method as it is the most effective, least effective to the environment and it is economically viable for South Africa.
The Gariep Dam is an example of hydroelectric power in South Africa, the company that runs that plant is Eskom, and the plant is very successful producing large amounts of power.
The Wind Turbines in Port Elizabeth are used to create kinetic and the turbines are strong enough to power a small town. The Coelga Wind Farm was the first wind farm built in South Africa which was built in the Eastern Cape; due to the success of the wind farm many more were built. The problem with wind turbines is they can't be used in a place such as Gauteng, because the wind is minimal and the wind turbines can't be turned and no power can be