The article "Wind power cheaper than coal" (yesterday) refers.
The problem with renewable energy sources like wind and photovoltaic is the unpredictability of the elements. This means that coal-fired power stations must still run to ensure integrity of power supply.
To achieve optimal use of these renewable sources, they could be linked to water storage systems, such as the hydro schemes in the Western Cape and KwaZulu-Natal, for use as peak-lopping sources. They could also be built to supply industries that do not require essential power sources.
Until our scientists develop nuclear-fusion power stations, it is a pipe dream to expect renewable energy sources to replace fossil fuels. Conventional nuclear power stations remain the most viable source of electrical energy.