Even though Eskom has stopped load shedding, there is still a risk that the electricity system could change at short notice, said acting head of generation Andrew Etzinger.
Etzinger spoke to Fin24 by phone on Monday and unpacked the status of the system.
The power utility had implemented load shedding for more then a week, due to plant failures as well as a loss of 900 MW of imports from the Cahora Bassa Dam in Mozambique as the country was affected by a cyclone.
Eskom has since stopped implementing load shedding due to "gradual improvements" to the system, the power utility said in a statement issued on Sunday evening.
Grid is 'healthy'
"The grid is in good shape and healthy," Etzinger told Fin24. But experience has shown the performance of power stations is not where it should be and is "unreliable".
"There is an underlying reality that things can change at short notice, as we saw last week. That is why we do not want to declare victory," Etzinger said. "We are not out of the woods".
Eskom is working hard to do the necessary maintenance, employ the necessary people and do the necessary training as well as secure the necessary funding, he said. But these things will take time.
Asked about the diesel shortage last week, which was a contributing factor to the load shedding, Etzinger explained that normally the open cycle gas turbines – which are powered by diesel – are run between two to three hours a day over peak evening periods. The problem came in when the plants were being run hard for up to 14 hours a day, much longer than they normally would.
As a result, diesel was not being replaced adequately given the rate at which it was being burnt, he explained.
Eskom managed to get 13 million litres of diesel reserves on Thursday, from state oil company Petro SA, which helped shift load shedding from Stage 4 to Stage 2. At Stage 4 load shedding, 4 000 MW are shed on a rotational basis while still meeting 80% of electricity demand. At Stage 2 load shedding, 2 000 MW are shed on a rotational basis.
Eskom is working with Petro SA to increase the availability of diesel proactively to avoid supply constraints when the open cycle gas turbines have to be run for 14 hours a day.
The focus is on making sure that there will be sufficient diesel for whatever usage pattern of the open cycle gas turbine is required, he explained.
Billions on diesel
Etzinger said that Eskom had gone significantly over the R600m budget in the emergency fund for diesel. For the current financial year which ends on March 31, 2019, R4.5bn has been used for diesel.
For the next financial Eskom plans to budget close to R7bn for diesel, this is to cater for running the open cycle gas turbines more frequently for the upcoming year, he explained.
Etzinger also gave an update on the tender process for the early detection system for tube leaks of the boiler system. Boiler tube leaks have led to trips at power stations, according to an internal memo on Eskom's operations, which was circulated among staff last week.
The contract of an early detection system had lapsed over a year ago, Fin24 previously reported.
'We're all on the same side'
However, system engineers at power stations are still able to flag leaks. The early detection system is a tool they can use to do that, Etzinger explained. The request to market for proposals had been issued last Monday and the request should be up for 10 days.
Additionally, Eskom is conducting a technical evaluation of Medupi power station, which Public Enterprises Minister Pravin Gordhan previously said had design defects which affected plant performance.
Government recently appointed a technical review team of 11 industry specialists which are also reviewing power stations. Although Eskom is trying to attend to issues at power stations, Etzinger said the recommendations of the task team will also be taken seriously.
"To the extent that the technical review team can assist, that would be much appreciated and we look forward to their recommendations," he said.
"We are all on the same side. We all want Eskom's power stations to perform more reliably and more productively," he said.