A key factor in the emergency was outages from planned maintenance on its plants, as the utility focused on ensuring enough supply capacity to tackle increased demand the cold winter months traditionally bring, Eskom chairman Zola Tsotsi said.
Outgoing Eskom CEO Brian Dames said the utility expected the system to remain tight throughout the winter regardless, but Eskom had “absolute control of the power system at all times”.
He said maintenance levels on generation infrastructure were higher than the same period last year, owing to an average infrastructure age of 30 years.
“Much of our infrastructure was built at the same time, which means it will be decommissioned around the same time, increasing the need for maintenance while our build programme rolls out,” he said.
The utility expected peak winter loads in excess of 36 000 MW, particularly between 5pm and 9pm, with electrical heating, geysers and pool pumps the main sources of demand.
In Monday’s system status update, Eskom said it had 33 000 MW available to meet supply, with the majority of 10 200 MW of unavailable supply tied up in planned maintenance.
Dames said maintenance would continue at high levels heading into winter – planned outages of between five and six gigawatts expected until April, whereafter it would steadily ramp down to around 1.75 gigawatts by June, when demand was expected to be at its highest.
While unplanned outages of 6 500 MW would generally keep supply above demand until the end of April, such outages would result in persistent state of emergencies in the higher-demand months of May and June, a graph in Dames’s presentation showed.
Eskom had therefore targeted an unplanned outage allowance of 4 500 MW for this period to keep supply out of the red.
Dames pointed out, however, that much of the planned maintenance done during summer would be complete in autumn, increasing available supply for the higher demand period.
He said the first 800 MW generating unit of the critical Medupi power station was on course for the end of the year – an essential addition to the grid, given wavering power reserves – to supplement supply.
“Hitachi (Power Africa) is doing corrective work on boiler welding at Medupi, and Siemens is working with Alstom to sort out interface software issues,” Dames said.
The first generating unit at Kusile was also on course for next year, he said.