About 45.15% of Eskom’s generation capacity was not available for service over the past week, energy analyst and MD at EE Business Intelligence Chris Yelland told Daily Maverick. 

The power utility announced on Wednesday that it needed to implement Stage 2 load shedding between 11pm and 5am on Wednesday and Thursday to recover and preserve emergency reserves, which were used to support the system after the early shutdown of Koeberg Unit 1 as well as other units that should have come back to service but were delayed. 

Eskom was experiencing greater-than-expected outages in the power system, Yelland said. 

Figures from Eskom’s Weekly System Status Report show that for the week ending on 4 January, on average 20.61% of the utility’s plant was down for planned maintenance, 21.26% was out because of unplanned maintenance and 3.28% was out of service due to other outage factors.  

It was planned to close down Koeberg Unit 1 at the end of January for repairs, but a leakage on a steam generator meant the unit closed down earlier.

On Wednesday, Eskom had unplanned breakdowns amounting to 12,000MW, as well as planned maintenance of just under 7,000MW, said Eskom spokesperson Sikonathi Mantshantsha. 

“That takes out some 19,000MW capacity from a system that is only able to generate 34,000MW at best,” he said.  

Additionally, the return to functionality could be delayed for a number of reasons, Mantshantsha said. 

 “[For example], the work done on them being bigger or taking longer than initially planned. Sometimes [delays] can be caused by the need [for] more work than was initially foreseen.” 

Breakdowns getting worse 

The combination of planned, unplanned and other outages had led to the need for the implementation of Stage 2 load shedding, Yelland said. 

Planned outages are very high at the moment because the utility is carrying out a lot of maintenance, as people use less electricity in summer, and the unplanned outages are also high owing to the early shutdown of Koeberg Unit 1, said Yelland. 

He said “other outages” are high because four units are down at the Camden Power Station.  

Camden Power Station has eight generation units, each with a total of 200MW, of which four units are in service and three are down because of an ash dam that has reached full capacity, Yelland said. Another unit was down for planned maintenance.

“[These] breakdowns are getting worse… because the plant is getting old.” 

A regular occurrence

According to Mantshantsha, the main reason and regular occurrence for generators going down is because of boiler tube leaks and other repair works.

“Each boiler has thousands of kilometres of tubes that have to tolerate high pressure and heat when working. Once in a while some of those tubes will break, causing the unit to be stopped while it is being cut out and replaced,” Yelland said 

Yelland said frequent boiler tube leaks were a sign of poor-quality coal, and systems getting old and not being maintained. “Inadequate planned maintenance, inadequate predictive maintenance and perhaps a lack of money.” 

Burning coal with a high ash content causes more wear and tear on the boiler tubes, and this should be controlled by preventative maintenance, said Yelland. 

“The idea behind this is to do the boiler tube repairs at the same time that you are doing a shutdown for other repairs, and this prevents unnecessary shutdowns. 

“It is easy to skip maintenance. It is easy to hide the problem. But you can’t hide it forever.” 

Running close to the edge 

Yelland noted that one reason for the high level of unplanned maintenance was because the power utility had skipped planned maintenance to keep the lights on. 

“Unfortunately, it always comes back to bite you in the end. If you don’t do the maintenance on a planned basis, you will do maintenance on an unplanned, breakdown basis.” DM