Eric Shunmagum, Eskom’s senior manager in the group executive generation office, said increased breakdowns and higher planned maintenance caused stage 6 load-shedding this week.
He told SABC that Eskom’s problems started on Saturday when seven generation units tripped, of which only four units could be recovered timeously.
“That trend continued into Sunday when we had to make some tough decisions. By Monday, we still have not recovered all the units,” he said.
On Monday, Eskom had planned maintenance of 5,700 MW, significantly higher than the 3,000 MW planned maintenance target during winter.
Unplanned breakdown maintenance hit 17,200 MW, which was also much higher than the winter target of 15,000 MW.
The higher planned and unplanned maintenance left Eskom with an additional 5,000 MW of lost generation capacity.
The increased maintenance resulted in Eskom’s energy availability factor (EAF) dropping to 52% in September. This is much lower than the same period last year.
The EAF for the 2023 calendar year-to-date is 54.52%, compared to 59.78% for the same period in 2022.
Simply put, the EAF decline means it has less generation power to serve South Africa’s electricity needs.
Another factor contributing to the higher load-shedding was the lower use of open-cycle gas turbines (OCGTs) to conserve diesel.
He explained that Eskom has a R30 billion diesel budget, which includes R19.4 billion for OCGTs and R9.5 billion for IPPs.
Eskom has already spent around R10.5 billion in the financial year-to-date, which means it must manage its budget to ensure it does not run out of money for diesel.
As such, Eskom is running fewer OCGTs, resulting in more intense load-shedding.
Eskom was running only four OCGTs on Thursday morning, far fewer than usual.
“Eskom’s generation division had very little choice other than to implement stage 6 load-shedding,” Shunmagum said.
“The increase in breakdown maintenance combined with the higher planned maintenance pushed us to a higher stage.”
Energy availability factor decline
The chart below, courtesy of Chris Yelland and EE Business Intelligence, shows the decline in Eskom’s EAF over the last three years.