The latest plant performance data from Eskom shows that the power utility appears to be determined to get its pumped storage levels up, even if it is at the cost of emergency diesel reserves.
This places the group – and the country – at increasing risk of high levels of load shedding, like stage 6 which came back into effect this past week.
Data compiled by independent energy analyst Pieter Jordaan shows that Eskom’s pumped storage – used to assist with peaking and dealing with sudden spikes in energy demand – has been used extensively over the last two weeks.
However, the storage has been pushed to new limits, with reserves tanking to just over 24% on Friday (24 November) – an all-time record low. This forced the power utility to escalate load shedding to stage 6 to restore these reserves.
Jordaan noted, though, that this habit is proving costly. Eskom is burning through diesel to assist with the pump storage reserves, which then leads to diesel shortages and the loss of the buffer provided by open cycle gas turbines (OCGTs).
For example the gains made from the diesel-assisted pumping on Saturday were largely reversed by Monday, as a lack of diesel on Sunday required the utility to again turn to pumped hydro generation, Jordaan said.
“However, the pumped hydro on Sunday required a 33% premium in pumping losses that some diesel supplies would have saved,” Jordaan said.
“In other words, it appears as if Eskom was bent on bringing the dam levels up – from an all-time record low of 24% on Friday – at the cost of completely depleting the ‘less expensive’ diesel reserves.”
This is also evident when analysing the group’s peaking sources – where it’s clear that there was no diesel left to run open-cycle gas turbines (OCGTs) on Sunday, and the pumped hydro – which took the diesel reserves to fill – had to be used.
Eskom’s use of peaking sources is escalating, with pumped storage and use of OCGTs ramping up due to increased demand and breakdowns sitting firm above 30% of capacity.
In Eskom’s fifth multi-year price determination (MYPD5), the regulator, Nersa, capped output from Eskom’s OCGTs at 1,266 GWh or R8.4 billion for financial year 2023/24.
However, Eskom has produced 2,665 gigawatt hours of energy from OCGT at an estimated cost of R17.8 billion, so far – more than double the NERSA cap.
According to Jordaan, South Africa has a historic pattern of a fortnight before the festive season, having a high upside risk for a widening supply gap, hence increasing levels of load shedding.
Recent demand increases have already widened the supply gap to 2.5 GW per hour, he said, which resulted in stage 6 load shedding. This suggests that the surge pattern has already started, albeit a week early, he said.
Despite the recent return of two large Kusile units, the unplanned outage levels continue to be higher than when the units went offline last year.
Eskom is also struggling to keep its EAF up, still being a far reach from the 65% goal it has set for March 2024.
Electricity forecasts for December 2023 and January 2024 paint a bleak picture of the incoming festive season, with the best-case scenario showing only six days without load shedding over the next two months.
Daily Maverick reported that this was revealed in a presentation by Eskom officials last week, which showed there would be load shedding between stages 1 and 3 throughout December at the very best, and between stages 4 and 6 every day at the very worst.
A similar best- and worst-case scenario is forecasted for January.
Electricity Minister Kgosientsho Ramokgopa promised that there would be fewer blackouts in December and that some days would be free of blackouts. This came as Ramokgopa said that some generating units are expected to return to service during the week, meaning more generating capacity.
In an interview on SABC’s unfiltered series, Ramokgopa even said load shedding will have ended by 24 December 2023. when asked if he was confident about this end date, Ramokgopa said, “I am more than confident”.
However, the forecast given by Eskom officials differs greatly from this promise.
Read: Eskom is in trouble