Why the lights went out last night

Thursday’s rolling blackout ought not to have come as a surprise …
What Eskom really needs is the time and space to do proper maintenance to improve plant reliability. But this is unpalatable politically, so the utility is forced to battle on. Image: Moneyweb

Eskom is battling a “constrained and vulnerable” generation fleet, with “plant performing at very low levels of reliability”.

In the 28 days since emergency overnight load shedding was implemented on November 7/8, so-called “unplanned breakdowns” were above the 9 500 megawatts (MW) level on practically half of them.

Read: Load shedding: How did it suddenly get to this?

An analysis by Moneyweb, using public data provided by Eskom, shows that these breakdowns were only below the 9 000MW level on three of the last 28 days. Importantly, the data published by Eskom provides only daily snapshots of breakdowns across the system at a point in time, generally between 6am and 8am.

This number is not static as some plants will return to service, while others may break down or experience partial load losses.

Source: Based on Eskom data

On Thursday morning, Eskom advised that unplanned breakdowns were at a worryingly high 12 300MW. By mid-afternoon, it experienced a “loss of additional generation” resulting in Stage 2 load shedding from 4pm. Stage 2 requires 2 000MW of load to be reduced, which means that breakdowns likely neared the 14 000MW level.

Eskom’s plan to avoid load shedding during summer requires unplanned breakdowns to be kept below the 9 500MW level. On top of that, it maintains a 2 200MW reserve margin to protect the grid in the case of additional breakdowns, trips or load losses.

Read: The problems with Eskom’s load shedding plan

When breakdowns exceed the 9 500MW level – Eskom actually forecasts using a “planned risk level” of 11 700MW of breakdowns – it has to rely on emergency generation resources, including pumped storage schemes and open cycle gas turbines, to ensure than an adequate operating margin is preserved. When that runs out of headroom (or if these emergency generation resources are unavailable), it has to resort to load shedding.

On November 7/8, given the high levels of breakdowns, it had to implement overnight load shedding so that it could replenish its pumped storage schemes.

The utility is increasingly using these schemes, which are net consumers of power (they require more power to operate than each unit of power they produce), to generate baseload power. Traditionally, pumped storage schemes are meant to operate as peaking plants only.

Along with this, Eskom is using as much as 3 500MW of power from renewable energy plants to supplement its own generation.

And it is relying on units at the Medupi and Kusile power stations that are not yet in commercial operation to provide anywhere from 900MW to 1 600MW of power daily. Medupi Unit 1, the only unit at that plant yet to be commercialised, is feeding an average of 400MW to the grid.

Core generation (illustrative)

Thursday November 7

Available dispatchable generation (peak)

33 107MW

Less renewables

1 657MW

Eskom dispatchable generation

31 450MW

Less non-commercial generation


Less imports

1 100MW

Less pumped storage

2 732MW

Less Koeberg

1 860MW

Less peaking plants (Acacia, Ankerlig, Gourikwa, Port Rex)

2 409MW

Available dispatchable core coal generation

22 868MW

 On November 7, with 10 500MW of unplanned breakdowns across the coal fleet, you can see the problem.

The total installed capacity of this fleet is around 40 000MW. Energy availability in this fleet is around 57%, far below the (still very low) 66.18% Eskom energy availability factor reported by the utility in that week. It needs the overall number to get above 70%, and ideally to 75%.

The longer-term problem for Eskom is that it continues to defer and “adjust down” the levels of planned maintenance to ensure that it has sufficient generation capacity.

It did, however, manage a level of 8.58% planned maintenance in the second quarter this year, versus a target of 7.5%. The summer plan calls for an average of 5 000MW of maintenance to be done across the seven months.

For now, things seem to be vaguely on track. But longer-term, not having the headroom to do enough maintenance translates into more unreliable plants and more breakdowns. It’s a vicious circle.

As at last week, Eskom’s planned outage factor was 9.85% in the year to date, versus 10.4% last year. This is a significant regression. Unplanned outages are at 21.01% in the year to date, versus 15.87% in 2018. This means that, on average, over 9 990MW of generation capacity has been unavailable due to breakdowns this year (versus an average of around 7 500 last year).

What Eskom really requires is the time and space to do proper maintenance to improve levels of plant reliability. Politically, this is unpalatable, so the utility is forced to battle on, trying to repair ageing plants while maintaining enough generation capacity.

Read: Load shedding over 10 years: Eskom, the economy and fiscal crisis

By winter next year, we’ll have some indication of whether Eskom has managed to do sufficient maintenance – it is too late now to change the course materially.

If not enough has been done, new CEO Andre De Ruyter’s first few months are likely to be quite the baptism by fire.



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Is it safe to braai on Christmas Day, or will Eskom also be switching off our fires ?

You are tempting fate, given their history & given half a chance, better have your gas braai ready.

Diesel for their turbines is expensive to them
…. and now they know you have gas braais after you’ve mentioned it….

I’m looking for a candle-powered one.

Note to “Logically speaking”: Correction – diesel is not expensive to them. It is expensive to us taxpayers who fund the continuous bail outs. But you are right on chancing their fortunes – you might soon be required to have a permit to cook with charcoal or gas. They’re already having a go at generators private individuals use.

It is what you get when 3rd world people try and play with 1st world toys !! They tend to break them !!!

Spot on. Give the Boeing keys to the kids and this is what you get.

…your 100th up-vote is from ME!

Sies jou rassis!….apologies, I meant “sies jou realis!”


Invest in SA-INC??


yup, no extra generation capacity = no growth.

More unemployment = more crime.

In SA crime pays, therefore desired outcome.

All you have to do to break the camel’s back is to switch on a oven. It’s not Eskom’s fault, it is our fault for using our ovens.

1st we had “load shedding”…

Now the Eishkom vocabulary has coined another phrase…so-called “unplanned breakdowns”…

What on earth is so-called “unplanned breakdowns”. Do we have anything like “planned breakdowns”…

Stru’s God, this government needs some “QUANTITY EASING”

Thanks ! You made my morning with that !

Unplanned breakdowns is what happens at board and senior management level; below this is sheer incompetence – case of blind leading the blind

Was definitely “planned” by the ANC since 1994. Took them a long time to wear it out.

Maybe it’s time to hire a few thousand more employees and pay big Christmas bonuses to everyone comrade Gordhan ? This should sort the problem out, ANC style.

Please don’t give them any ideas… next thing you know, they’ll be striking for higher pay.

Eskom is battling a “constrained and vulnerable” generation fleet, with “plant performing at very low levels of reliability”.

This lot have yet to realize that Eskom is perhaps an essential entity. It cannot break down.

Note it is the machinery and plant’s fault, broken or underperforming. No human element at all. Next they will blame the aprtheid era, not having installed good enough stuff. Like the Queenstown councillor who blames the apartheid era for half full dams. They built them too big.

I see a black Christmas looming. First SAA and now Eskom over the edge.

This plant is manufactured in the developed world (That’s why it’s called “developed.” Where else?).
So the “unplanned breakdowns: are a Western counter-revolutionary plot.

Arrest of terrorists in progress!!!

Anybody have a coal fired Aga for sale? Seriously.

Well said Joe. You have the best plan. Aga might become a status symbol in the years to come.

Eskom might even have a bunch of surplus coal for sale (discounted?), which will make your Aga a superb investment.

because they dont know what they are doing?

Looks like eskom needs more hands on deck. Especially to towel off the wet coal when it rains. When Medupi and Khusile come online in 2035 our problems will be over, so just sit tight and stop panicking.

Thanks! Needed a good laugh.

Time for all the SOE’s to be put under voluntary business rescue management then shut them down. Like SAA. In the meantime let and overseas company take over the supply of power to the grid. Maybe even Zimbabwe…:-)

Can this Eskom piece of rubbish please die already!!!! This thing is more trouble its worth…..like the politicians who think they can run it….die already!!!

I wouldn’t trust the numbers that Eskom posts up on it’s own webpage.
If, as per the schedule, stage 4 = 4GW load-shed and that is approx. 6hr per 24hr window i.e. = 25%. Would that not mean that there’s closer to 16GW to max 20GW available for distribution…?

I may be missing the point, but that makes sense, doesn’t it?

I did a quick deep dive analysis of Installed versus Planned versus Actual at ESKOM, from independent review…

Installed: +-47500MW
Planned*: +-30500MW (far lower than National Demand of 35000MW at times)
*This Already assumes losses of 16500MW Generation Capacity 30%!!!)
Stage 6: Further 6000MW Lost

Assuming Demand did not increase, then actual availability dropped to 24500, or 52% of of Real Capacity, to force stage 6 loadshedding.

This is the real shed capacity (48%), and the continued propaganda that only 6000MW is being shed is fabricated mis-information in my view…

If we correlate Capacity with the real cost of generation and operation, then the SOE is loosing 48% of potential revenue, and unless we wake up and sort ESKOM out, this will just get lower and lower until they wake up too late (LIKE with SAA, where losses are just as great)…

Just my thoughts for the day…

If you are not in a rage with how this country is being managed and governed there must be something wrong with you or your immigration papers have just come through. The ANC has perpetrated one of the greatest failures in the history of man on this country and those that continue to vote for them should hold their heads in shame.

End of comments.





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