Unavailable capacity: Charting Eskom’s load shedding week from hell

Before the current bout of load shedding, Memeburn’s last article about the Eskom crisis was published in mid-November.

Back then, I thought it would be the last we’d hear about it.

At the time, the power utility noted that it was monitoring a “constrained and vulnerable system”, but after weeks of posting similar messages to Twitter, we didn’t quite realise just how vulnerable it was.

But today, on Monday 9 December, the crisis deepened, and the numbers of Eskom’s power production slide demonstrates just how deep that hole is.

Eskom’s unplanned breakdowns

On 2 December, three days before load shedding was implemented for the first time in a month, Eskom said that 9100MW of generational capacity was unavailable.

It added that the system was performing at “very low levels of reliability”, but the situation seemed under control. Eskom’s load shedding avoidance goal sits at 9500MW, so it had some 400MW of wiggle room.

But on 5 December, Stage 2 load shedding was implemented, and that unavailable capacity jumped to “above 12 500MW”. To add to these woes, it also “experienced an increase of more than 1000MW in demand”.

It also cited rainy weather as a potential issue.

This all came to a head just a day later. Stage 4 load shedding re-emerged for the first time since February.

Eskom failed to provide an exact figure for its unavailable capacity at the time, but stated it was “above 12 000MW”.

Some of the utility’s coal reserves were saturated with rain, power stations were tripping, and diesel was being burnt. Eskom also dug into its pumped storage scheme reserves to supplement power delivery.

Nevertheless, and probably due to lower demand, the situation improved over the weekend. On 7 December, unavailable capacity stood at 11 600MW but Stage 2 load shedding was in effect until Sunday to allow the utility to build up pumped storage reserves.

However, on Monday, the situation grew much worse. Its unavailable capacity spiked by 2800MW.

As South Africans returned to work, 14 200MW — of more than 37% of Eskom’s total installed generation capacity — was unavailable. This, with a 600MW surge in demand meant that Eskom was faced with one of its toughest days of the year.

Note, Eskom’s installed capacity sits at 37 745MW.

At the time of writing, Stage 4 load shedding is in effect once more.

Can it get any worse than Stage 4?

In March, Eskom announced that Stage 5 and Stage 6 load shedding schedules do exist. In fact, numbers up to 8 are accounted for.

It said then that it was not “formally planning to implement stages 5 and beyond” and that it would do “everything in its power to improve system performance”.

But nearly eight months later, it seems that not much has improved at all.

Feature image: Eskom’s Koeberg Nuclear Power Station just north of Cape Town, by Paul Scott via Flickr (CC 2.0 BY-SA, resized)