After having operated South Africa’s electricity system without resorting to rotational power cuts for 310 days, Eskom declared Stage 3 loadshedding at 17:00 on January 31, after the loss of 3 600 MW of coal capacity resulted in a depletion of diesel and pumped-storage reserves.

Describing the development as a “sad moment” and a “setback”, Electricity and Energy Minister Dr Kgosientsho Romokgopa nevertheless insisted that Eskom’s operational performance remained on an upward trend.

He also indicated that he was still expecting to declare a definitive end to loadshedding within the not-too-distant future.

The trigger for such an announcement, he said, would probably be once all three units at Kusile that had been operating using temporary stacks were reintroduced permanently, and once Kusile Unit 6 entered commercial operation and Medupi Unit 4 was returned to service. This, in addition to Koeberg Unit 2, which was returned after an extended outage in December.

Eskom CEO Dan Marokane issued a loadshedding warning on Friday morning, indicating that the risk had been elevated as a result of several breakdowns that required extended repair times and which had also required the utility to draw down emergency reserves.

On Friday afternoon he reported that loadshedding would indeed be implemented, after unplanned breakdowns rose to about 13 GW, amid ongoing planned summer maintenance of some 6 GW.

Group executive for generation Bheki Nxumalo attributed the rise in unplanned breakdowns primarily to the loss of six units earlier in the week at the normally reliable Matimba and Lethabo power stations.

He said the main cause was boiler tube leaks.

Given that the repairs were taking some time to complete, Eskom had resorted to operating its diesel-fuelled open cycle gas turbines (OCGTs) at high levels and had also drawn heavily on the OCGTs operated by independent power producers and its pumped hydro schemes.

As a result these emergency reserves had been depleted and the system operator had indicated that loadshedding would be required to help replenish the water and diesel stocks, especially at the Ankerlig OCGT facility in the Western Cape, which relied on road transport for its diesel supply.

Marokane insisted that it was an operational rather than a financial decision, stressing that the company, which reported a R17-billion interim profit, had sufficient financial resources to buy diesel.

Eskom indicated that it hoped to end loadshedding by Monday, but cautioned that this would depend on its success in returning several coal units as intended.