Brace for more load-shedding in the next few months as Eskom services its ‘most reliable’ machinery

Eskom has warned South Africans they should expect more load-shedding in the coming weeks as it s embarks on major repairs and capital investment projects that will increase the risk of outages.

According to Eskom group COO Jan Oberholzer, a unit at Koeberg power station will undergo scheduled maintenance from December 8 until June next year. 

“Unit 1 of the Koeberg nuclear power station, which has enjoyed 384 days of uninterrupted supply, will be shut down for normal maintenance and refuelling, and the replacement of the three steam generators as part of the long-term operation to extend its operating life.”

He said Koeberg is the most reliable of Eskom’s generation machines.

“This will remove 920MW of generation capacity from the national grid during this time.”

With other repairs at other power stations, Oberholzer said load-shedding risk factors will remove more than 2,300MW of generating capacity from the system, and cautioned the public to anticipate an increased risk of load-shedding until the repairs and maintenance were complete over the next six to 12 months.

Oberholzer said the main concern is high levels of unplanned outages, which contributed to the 155 days of load-shedding experienced since January.

He said to limit the stages of load-shedding, Eskom had to rely heavily on extensive use of open-cycle gas turbines, burning millions of litres of diesel.

“Due to the vulnerability and unpredictability of the power system, coupled with the major capital projects and maintenance and major repairs to be executed during the next few months, the risk of continued load-shedding remains quite high.”

Oberholzer said Koeberg unit 2 was returned to service after a forced shutdown to remedy the control rod slippage issue and has been operating for 51 days.

He said the October 23 duct (chimney) structural collapse that shut unit 1 at Kusile, and the decision to delay the return to service of units 2 and 3 as a precautionary measure, has inflicted another serious blow to Eskom’s efforts to improve the availability of generation capacity and reduce the implementation of load-shedding.

The loss of the Kusile units has added additional strain to an already constrained generation system.

Unit 4 is the only one on load at Kusile.

Oberholzer said the extent of the damage to the Kusile duct system will be established over the next few weeks as investigations into the structural failure pick up speed.

He said the investigations will also establish whether there is any risk to unit 3 at Kusile. Its chimney is housed in the same stack as the other two units.

He said returning the Kusile units to service is at least a few months away.

“This is the reality of operating a shrunken generation system bereft of any reserve margin. Every breakdown pushes the whole system to the edge.

“This loss of capacity, temporary as it is, will make for a very challenging summer season, particularly as this is our peak planned maintenance period when a number of units at  power stations have to be shut down to conduct much-needed maintenance.

“While Eskom works on returning these large units to service, we will have to continue limping along to meet the demand for electricity, particularly over the next six to 12 months.”

Coal stock and rain readiness

The power utility said it continues to experience a tough period in terms of its generation operations, especially on the coal generation side of the business, with the year-to-date energy availability factor (EAF) falling to 58.53%.

Acting MD for generation Thomas Conradie said the high levels of planned maintenance, impacted by a high rate of breakdowns, contributed to the low EAF.

Conradie said there has, however, been notable progress and sustained good performance in several aspects of the business. Coal stock levels are healthy at an average 35 days, excluding Medupi. Including Medupi, this doubles coal stock days to just under 70.

He said rain readiness plans have proved to be resilient and withstood unusually high summer rainfall season last year, which included heavy storms that caused considerable damage in some parts of the country with critical generation infrastructure.

Conradie said plans are in place for the current rainy season.

“All coal-fired power stations’ plans have been stress-tested to ensure they are again able to withstand the high rainfall period.”

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