South Africans are facing another round of power cuts despite promises from South Africa’s power utility, Eskom, that it would keep the lights on.
Unexpected breakdowns and scheduled maintenance at various generation plants have been blamed for reduced generation capacity.
The power grid in South Africa is made up of three building blocks: generation, transmission and distribution.
Generation consists of power stations (or plants) that generate electricity. Examples of these are the newly built Kusile and Medupi power stations.
South Africa has a generation capacity of approximately 58 GW – enough to power 26 million kettles concurrently – mostly made up of Eskom’s coal-burning power plants. Eskom’s share of this is a generation capacity of 44 GW, of which 38 GW is from coal-powered stations.
Transmission comprises the 28 000 km of high voltage lines that transport electricity at high voltage levels (such as 400 kV or 765 kV) to cities and towns.
There, it branches out to 325,000 km of lower-voltage lines that distribute electricity to homes and businesses. In comparison, New Zealand has 150,000 km for a tenth of South Africa’s population and the UK has over 800,000 km.
When generation can’t keep up with demand, the grid is threatened.
When no generation is happening, the grid collapses and there’s a blackout. This has happened before in various other countries.
For example the 2019 blackout in Argentina left 48 million users without power for most of a day, while 55 million North Americans were left in the dark for a fortnight in 2003.
These examples are dwarfed by the 2012 blackout in India, which affected over 400 million users.
To avoid a collapse of the grid, Eskom, which controls the grid frequency from a National Control Centre in Johannesburg, has put in place a severe form of demand management for situations in which demand starts to outstrip supply.
It imposes a series of planned power cuts — called load-shedding — to reduce demand. If the situation is extremely bad it institutes Stage 4 load shedding, which means 4GW of the total demand is cut on a rolling schedule.
A total collapse of the system would mean that the country — and some countries in the region — would be without power for extended periods rather than the 2- to 4-hour periods that are currently the norm.
It hasn’t happened in South Africa yet because of Eskom’s well-co-ordinated and responsive demand management – and good fortune.
Such a collapse of the grid would require generation plants being brought back online in synchronisation with the 50Hz, which means they have to be ramped up and added one by one.
The reconnection of all the generators after a blackout would probably take two weeks or more, leaving large parts of the country and some neighbouring countries without electricity for days or more as plants, and limited critical demand, are gradually turned on.
During the time it takes for the grid to come back online, there will be disruption to communications, manufacturing, financing and logistics around the country.
Source: Supermarket & Retailer