Eskom appears to have learnt from experience by being able to handle periods of heavy rainfall and the impact that this can have on coal stocks.
According to the power utility, heavy rain experienced in December and the first weeks of January across large parts of the country — including Gauteng and Mpumalanga where the majority of its coal-fired power stations are located — did result in some load losses, but contingency plans meant the losses were insignificant.
Responding to questions from Business Day, Eskom said that all generation sites had to undertake annual assessments of their wet-coal handling procedures as part of their preparation reviews.
“This takes into account challenges experienced or best practices from other generation sites during the previous rainy season,” Eskom said in a statement. Slopes on the stockpiles to allow for improved water run-off and channels diverting water away from the stockpiles were inspected and managed after every significant rainfall, it added.
Besides wet coal stockpiles, heavy or persistent rain can affect mining operations, and limit the steady supply of coal, according to Chris Yelland, energy analyst and MD of EE Business Intelligence.
“It doesn’t really matter when chunks of coal get wet, but problems start occurring when the coal fines [coal dust] at the bottom of a stockpile get wet,” Yelland said. Wet granulated coal forms a sludge that can stick to the conveyor belts that carry the coal to the boilers, clogging up the system, he said.
“If you get to bottom of stockpile things get worse,” Yelland added. That is why Eskom has to maintain a coal stockpile of 20 days to avoid crisis.
Eskom confirmed that at January 17 all its power stations had adequate coal supplies, with total system coal stock days at 80.1 days and no plants were below the grid code.
According to Eskom, while there would be no load-shedding as a direct result of the rain, the likelihood existed that power cuts would occur.
“The reality is that the risk of load-shedding occurring this year is much more elevated due to the numerous large capital projects that are under way, particularly at Koeberg and while the recovery of Medupi’s Unit 4 is in progress.”
On Monday, Unit 2 of the Koeberg power station was taken offline for a regular refuelling and maintenance that was scheduled to take five months, Eskom said in a statement. The Koeberg Unit 1 outage, of a similar duration, is set for later in the year when the unit’s steam generators will also be replaced.
Eskom warned that the extended unavailability of the units meant the supply system may be under additional strain in the year ahead.
Besides Koeberg, at least one unit at all plants will undergo planned maintenance over the next six months, resulting in power cuts as per the outage schedule or shorter outages due to unplanned breakdowns or other issues.
Update: January 24 2022
This story was updated to reflect changes made to a statement given by Eskom in response to questions submitted by Business Day. In its original response, Eskom stated that it did not expect any load-shedding to occur within the first months of 2022. However, that was amended in a subsequent statement from the utility to indicate that the risk of load-shedding occurring in 2022 remained high.
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