Coal still key to SA energy mix
A target of 50% clean power is feasible for SA
South Africa’s power utility Eskom has not been able to provide a steady electricity supply for several years now.
At the start of this winter the utility warned the public to expect up to 100 days with rolling power outages. At the end of last month there was at times a 6000MW shortfall in electricity supply, or about 20% of the evening peak demand.
While there is consensus that new electricity generating plants are urgently needed to minimise power outages, there are radically differing views on how this is to be achieved.
One widely promoted view is that increasing electricity generating capacity requires grand scale new renewable energy developments. In 2020, the electricity generated from renewables amounted to a mere 10.5% of the national total. This will have grown to about 11.5% as more plants have been completed.
Most people associate renewable energy exclusively with wind and solar energy, but it includes all technologies that don’t process non-replaceable fossil fuels. Fossils include coal, oil, gas and minerals.
Hydropower stations, which extract electricity from the downhill flow of water, are a renewable energy source. This is the major source of electricity in water-rich countries such as Norway, but only a limited option in drier climates.
Other renewable energy technologies like geothermal and tidal power generation work in select localities that are not common in South Africa.
This leaves wind and solar. These sources make up about 8% of South Africa’s energy mix. Wind and solar power are very attractive because:
• South Africa has some of the best solar and wind resources in the world;
• Solar and wind plants can be built in less than two years;
• Prices of solar and wind technology have dropped very sharply in the past 10 years; and
• Their extremely low carbon emissions mitigate global warming and make solar and wind energy attractive to investors.
Solar and wind power, however, have obvious drawbacks. The main one is that their operational capacity entirely depends on the weather. Furthermore, solar energy production is linked to the daynight cycle, with maximum efficiency around noon. This doesn’t coincide with the electricity demand peaks in the early morning and early evening.
In theory, with South Africa’s wind and solar resources superior to other countries with 100% renewable electricity ambitions, this should be a relatively easy target to reach. But other countries are often grid-connected to neighbours with significant power production. This means they can draw on these when weather conditions are unfavourable.
That is why a renewable electricity system can’t become the dominant power source in South Africa until electricity storage technologies become practical and economical.
A target of 50% electricity from renewables is, however, perfectly feasible. It’s the minimum that the country should aspire to. Even the 2019 electricity plan projected this would happen by 2050.
Considering the climatic advantage, the fraction of electricity generated from renewable energy technologies is surprisingly low, but despite this there is significant hostility to renewable developments as some sectors have interests in maintaining the coal-dominated status quo.
In assessing the contribution of renewable energy sources it’s important to distinguish between power (the rate at which it is produced at any particular moment) and energy (the total produced over an extended time period). In view of the variability of the wind strength and the intermittence of sunlight, these technologies only occasionally produce power at top capacity. In typical South African conditions a 100MW solar or wind plant only generates about a third of the energy of a functioning 100MW coal plant.
Overcoming the present 6000MW power shortages therefore requires about 15 000MW of new solar and wind plants. The continuing deterioration in the efficiency of the large coal power plants means that the actual need for new renewable generating capacity in the next five years is closer to 20000MW.
President Cyril Ramaphosa’s announcement that drastic steps are imminent to combat the electricity crisis is likely to amount to a major drive towards more renewables.