Eskom’s winter load shedding scenarios – risk of stage 8 extremely high

Interim Eskom group chief executive officer Calib Cassim says that the risk of stage 8 load shedding this winter is “extremely high” if the group cannot contain unplanned losses.

Speaking at a State of the System briefing on Thursday (18 May), Cassim repeated that the coming winter months – which have already started to set in – are going to be a very difficult time for the country and warned that South Africans should anticipate a struggle.

Compared to winter 2022, the country will be entering the cold period with 3,000MW offline due to various long-term outages – such as those at Kusile and Medupi, as well as unit 1 of Koeberg being offline.

He said that the power utility and the system operator have worked hard to develop a load shedding mitigation plan, with a particular focus on the energy availability factor (EAF) of power stations.

However, in order to achieve this, Cassim said that Eskom needs to keep unplanned load losses below 15,000MW. He added that if losses exceed 18,000MW, the risk of stage 8 load shedding is extremely high.

At stage 6, consumers suffer outages for 12 hours in a 32-hour cycle. At stage 8, this escalates to 16 hours in a 32-hour cycle.

The issue is that, by its own admission, Eskom has simply been unable to consistently contain losses below these levels – making the worst-case scenario more likely.

According to Eskom, the country is entering winter with a near 6,500MW shortfall, with demand expected to reach 33,000MW against a supply of around 26,500MW.

Energy demand in 2022 was around 34,000MW and has spiked higher in the past. Supply, meanwhile, has dropped below 24,000MW in recent months – even before increased winter demand.

Under its scenario modelling, depending on how severe losses are, load shedding will be as low as stage 3 to stage 5 in the base case – or could go as high as stage 7 and stage 8.

In most cases, however, load shedding will likely be in effect permanently over winter.

The group stressed that the scenarios are flexible and not static in any way, with the situation changing regularly.

According to Eskom chair, Mpho Makwana, the pressure from the winter months is exacerbated by shifting weather patterns, with recent wet weather in Johannesburg showing a dramatic change to typical conditions.

“The power system will be even more constrained, and weather forecasters are predicting a harsh winter,” he said.

In terms of mitigation, Eskom said it will be cutting planned maintenance to try and conserve megawatts wherever it can; it will also be turning to its Open Cycle Gas Turbines (OCGTs) and burning more diesel to try and keep the lights on.

Makwana repeated the group’s intention to push forward with demand-side management, which should assist with curbing energy demand during the winter months.

However, most of the load shedding relief is only expected once winter has passed.

Makwana noted that this will also be the first winter without 960MW from Koeberg Unit 1, which will only be back on the grid by September.

He added that some downed units at Kusile will also only be back online by November 2023, which should provide some relief. He expects overall EAF to be at 65% by the end of the financial year, ie, by the end of March 2024.

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