On Saturday it had already become apparent just how much trouble Eskom’s generating unit was in.
At that evening’s peak – during the Easter long weekend when electricity demand was more than 5 000 megawatts (MW) lower than it would’ve been on a weekday – the utility could only provide 27 633MW of capacity. And this included the use of 11 open cycle gas turbines (OCGTs). Renewables contributed just less than 1 500MW.
The writing was on the wall.
The utility was forced to implement Stage 2 load shedding abruptly on Sunday afternoon when breakdowns hit critical levels.
What it refers to as “unplanned breakdowns” totalled 17 018MW – what appeared to be a record high. Eskom executives on Tuesday morning confirmed that this was “not a new record for unavailable generation”.
Remember Stage 6 load shedding?
The previous worst publicly disclosed level was 16 700MW in May last year.
Before that, it was 15 921MW in January 2020, roughly a month after it was forced into unprecedented Stage 6 load shedding (where outages were likely around the 17 000MW level but were not disclosed at the time).
Added to the 17 000MW on Saturday was planned maintenance, which totalled 5 474MW.
Just a month ago, it had forecast that planned maintenance would total 6 249MW in the last week (higher than the 5 114MW forecast at the start of the year).
Eskom has constantly been rolling over maintenance that it has scheduled as it battles to keep generation from the coal fleet at adequate levels.
This deferral of maintenance has a knock-on effect: the coal plants become more unreliable, forcing it to run working units harder which, in turn, affects their reliability. Those maintenance ‘bills’ eventually come due, as we’re experiencing.
Of the 22 492MW offline (planned and unplanned), Koeberg Unit 2 (offline for refuelling and maintenance) accounts for 970MW. Practically all the rest (barring perhaps some capacity at the Ingula pumped storage scheme which has experienced some challenges due to high dam levels) is Eskom’s core coal fleet.
Easily more than 20 000MW of coal generation capacity is offline (including Medupi Unit 4, which exploded in August last year and accounts for 720MW).
The utility has 38 000MW of total coal generation capacity, which means 53% was offline on Sunday.
The past week …
Over the past week, it has used an enormous amount of diesel as well as emergency measures such as interruptible load supply and virtual power supply (where it cuts power to large customers, primarily the aluminium smelters) just to keep the lights on. And that was in addition to load shedding from Monday evening until Friday at 05:00.
|Mon Apr 11||Tues Apr 12||Wed Apr 13||Thurs Apr 14||Fri Apr 15||Sat Apr 16||Sun Apr 17||Mon Apr 18|
|Eskom capacity (MW)||29928||28637||27919||27519||27323||27633||26717||27836|
|Virtual power station (MW)||230||203||158||153||–||–||–||–|
|Interruptible load supply (MW)||897||–||–||–||–||–||–||1124|
|Load shedding (MW)||2082||2485||2056||1831||–||–||1818||1966|
|Total demand (MW)||32749||30878||29982||27373||24726||27109||28873||30401|
Its available generation deteriorated throughout the last week and reached just 26 717 MW on Sunday evening.
Recent data from Eskom shows it is also reliant on between 540MW and 720MW of non-commercial generation from Kusile Unit 4 which is set to be fully commissioned in July. That unit has provided power at the peak since March 21 (until at least April 10, the date to which Eskom has disclosed detailed system capacity).
Eskom says “the power system continues to be fragile” and “unpredictable” and warned on Sunday that “any further deterioration in generation capacity may require higher stages of load shedding”. Load shedding was increased to Stage 4 on Tuesday morning due to Majuba Unit 5 and Tutuka Unit 4 tripping.
Regretfully, Eskom has just been forced to implement Stage 4 loadshedding at 07:20 following Majuba Unit 5 and Tutuka Unit 4 tripping. A full statement will be published in due course.
— Eskom Hld SOC Ltd (@Eskom_SA) April 19, 2022
It is worth highlighting too that miners at Sibanye-Stillwater’s gold operations remain on strike and the mines are therefore not operating.
Imagine the situation we’d be in with these large consumers of power running at full capacity.
Remember, peak winter demand is around 33 000MW (we reached 32 749MW at 18:10 last Monday and it’s not exactly freezing yet). Koeberg Unit 2 is scheduled to return to service in June which will provide some headroom (over 900MW).
Until then, brace yourselves.