Economists warn risk of total grid collapse is higher — Eskom denies it
Eskom has denied that it has put more strain on its generating system in the past few weeks to avoid higher levels of load-shedding.
The response comes after a News24 report in which Nedbank chief economist Nicky Weimar and independent political and economic analyst JP Landman said they believed the threat of a grid collapse was elevated.
Weimar said Eskom’s electricity demand and availability figures suggested the grid was teetering on the edge of a blackout in February 2023.
She questioned whether the recent reduction in load-shedding was possibly a strategy to create the impression that the newly-appointed electricity minister’s work had borne fruit.
Landman alleged that Eskom was manipulating the load-shedding schedule, which he maintained was evidenced by the operating reserve margin deteriorating.
This ratio refers to the gap between peak demand and Eskom’s nominal capacity.
News24 pointed out that the utility had previously acknowledged an “acceptable” margin should be 15% of the nominal capacity.
However, according to the report, Eskom’s operating reserve margin was supposedly negative for most of February and into the first half of March 2023.
Another red flag for the economists was that Eskom had stopped publishing its daily evening peak demand statistics, further fueling speculation that something untoward was happening.
During the three-year tenure of Eskom spokesperson Sikonathi Mantshantsha, Twitter users had grown accustomed to a daily update on the state of Eskom’s generating system during the evening peak demand period.
Mantshantsha’s final tweet with these statistics was published on his last day in office on 28 February 2023.
Feedback from Evening Peak 28/02/2023, 19:18
Total Demand: 28 801MW
Loadshedding: 3 918MW
Virtual Power Station: 308MW
Eskom OCGT’s Utilised: 10
IPP OCGT’s Utilised: 6
Renewable Gen: 1 958MW (Wind 1 533MW, CSP 344MW, PV 81MW)@Eskom_SA Available Generation Capacity: 24 770MW— SikonathiMantshantsh (@SikonathiM) February 28, 2023
Following Mantshantsha leaving the company, the updates were switched to a WhatsApp Communities group and posted by acting spokesperson Daphne Mokwena.
Eskom uses this channel to communicate with the media and other stakeholders on the latest developments at the utility, including press releases that are distributed to the general public on Twitter.
However, until today the last peak evening demand statistics were sent on 18 March 2023, meaning that journalists and energy analysts have not been able to get a view of the generation scenario.
But the utility told MyBroadband there was nothing sinister about stopping the publication of evening peak demand statistics and reducing its operating reserve margins in the past few weeks.
It blamed feedback from the media about the format of the statistics for a temporary halt in publishing them.
“After being told that the message is ‘gobbledygook’ by some journalists, Eskom is relooking at what is published in order to make it more meaningful,” the utility stated. “This requires some automation and will take some time.”
Mokwena posted the first set of reformatted peak evening demand statistics at 00:16 on Wednesday, 5 April. They were as follows:
Evening Peak 04/04/2023 (18:30)
Total Demand: 31 240 MW 🔺
Eskom Availability: 25 405 MW.🔺
Renewable Gen: 900 MW
Load shedding: 4021 MW
~~~~~~
Number of OCGT’s Utilised: 11Renewable Gen: (Wind 519 MW, CSP 327 MW, PV 54 MW.)
IPP Availability (Dispatchable): 1014 MW
Eskom also said the concept of a reserve margin was “outdated” for a power system that relied on renewable generation to contribute towards supplying demand.
Renewable generation like wind and solar are notoriously unpredictable, meaning their contributions to the grid can fluctuate dramatically over a short period.
For this reason, the Eskom System Operator ensures that sufficient reserves are maintained in real-time to react to unexpected incidents in the power system.
“Currently, this reserve requirement is 2,200MW,” Eskom said. That works out to about 4.8% of Eskom’s 45,000MW nominal capacity, over three times less than the 15% the economists expected.
It’s worth noting that outgoing Eskom chief operating officer Jan Oberholzer had already acknowledged this was Eskom’s situation as far back as 2019, so this is nothing new.
The only solution to maintaining that reserve is to implement load-shedding, which is what the Eskom System Operator led by Isabel Fick does.
Eskom also highlighted two documents that explained Eskom’s approach to reserve margins in more detail — Eskom’s most recent ancillary services technical requirements and medium-term system adequacy outlook published in October 2022.
The table below summarises Eskom generation reserve requirements for the next five years, with the 2,200MW operating reserve margin highlighted.
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