It could be argued that a degree of subsidy may be necessary for the development and early adoption of new technologies.
Three questions arise in my mind about the extent of renewables in the SA electricity mix.
1. Is SA currently dependent on wind farm output in times of peak demand?
2. Although wind power is variable, is it sufficiently predictable in the short term (several hours?) to not unduly affect the current market dispatch processes, which if they fail would lead to loss of reserve conditions?
3. Given the peakiness of demand (both daily and annual), are there not always going to be issues re the viability of the generation plant (whatever its nature) required to meet marginal demand?
Don't disagree, but wind power can and never will be a base load 100% reliable energy source.
1. SA has over 1500MW of wind capacity which if all running at full capacity can much of the time handles 100% of SA's power requirements. Right now they are at just under 1700MW.
2. If the peaking stations are ready, they can start up at any time to ensure there is no blackout, but they have to be ready including a gas contract. You always have a element of buffer in your capacity, called "spinning reserve" to deal with a trip/failure at any one location and this would be wind dying down.
3. Yes. If the base load capacity was running at 100%, lets say 1100MW which is pretty much SA's quiet time. Then you need either reserve in your base load or peak capacity to handle the peaks. I agree wind turbine, solar or not, they still need to deal with it. However Wind and solar are whats called non-synchronized capacity (they use inverters to make AC) so they cannot supply the grid on their own, they need to be tied to an equally large synchronized supply.
The other problem is that the base generators have been kicked off as the wind supply is too high and now the base load is operating more like peak and does not have the gas supply contracts in place to handle periods of extreme load. Likewise many of the peak stations.
The general rule of thumb if you ready the industry papers on wind is max 20-25% of grid capacity. This would be fine if SA had a more robust and higher capacity inter connection with the eastern states