This is what Stage 12 load shedding would likely mean

At least Eskom has made an about-turn on the load shedding plan beyond Stage 8.

Last week, Eskom System Operator GM Isabel Fick admitted that it is working with the National Energy Regulator of South Africa (Nersa) on preparing schedules beyond Stage 8.

Read: Eskom totally irresponsible not to have schedules beyond Stage 8

This was confirmed later by acting head of generation Thomas Conradie on Saturday, who said guidelines on stages 8 to 16 were being drawn up for approval by Nersa.

Recall that in September, Fick revealed that Eskom does not have load shedding schedules beyond Stage 8. If that happens, the current plan is to issue individual instructions to provinces and municipalities.

Read: The South African towns where electricity supply is privatised

This is completely unworkable and would mean complete chaos, something which Eskom seems to have grasped.

So, there’s now a plan to have a plan …

One needs to pause to realise just how terrifyingly huge the still-theoretical Stage 16 would be.

Using Eskom’s current methodology where Stage 1 = 1 000MW, Stage 2 = 2 000MW and so on, Stage 16 would require 16 000MW of demand to be cut. Peak demand in summer is around 30 000MW (in winter, this number will be ±34 000MW). This means that a 16 000MW cut would equate to roughly half the demand in South Africa (including exports).

At Stage 8, the average electricity user would be without power for half the day – practically three four-hour blocks each day (technically 3 x 4.5 hours, if one factors in the restoration window).

These schedules already exist, and the existing timetables work on a four-day cycle from the first of every month.

Extrapolating this methodology to additional stages is simple, in theory …

Number of two-hour slots in four-day cycle Total hours of load shedding in four-day cycle (96 hours)
Stage 1 3 6
Stage 2 6 12
Stage 3 9 18
Stage 4 12 24
Stage 5 15 (including three four-hour blocks) 30
Stage 6 18 (including six four-hour blocks) 36
Stage 7 21 (including nine four-hour blocks) 42
Stage 8 24 (12 four-hour blocks) 48
Stage 9? 27 (including three six-hour blocks) 54
Stage 10? 30 (including six six-hour blocks) 60
Stage 11? 33 (nine six-hour blocks) 66
Stage 12? 36 (16 six-hour blocks) 72

* At this point, stages beyond Stage 8 are purely theoretical.

However by Stage 16, where the frequency of Stage 8 is doubled, the number of hours of load shedding across a four-day cycle is 96 – meaning no electricity at all. This doesn’t exactly make any practical sense. At that point, 16 000MW of demand has been cut, yet there would still be a material amount of generation capacity online (easily over 1 0000MW).

Some power would still be exported to neighbouring countries and large industrial users (including South32’s aluminium smelters) would still be supplied under contract. The diversified miner confirmed to Moneyweb in January that “the (two) smelters consume 2 155MW which is (roughly) 5% of Eskom’s installed capacity or (about) 7% of its average daily peak.”

Interruptions can only be made to the supply to Hillside at Richards Bay and Mozal (via the exports to Mozambique) for a certain number of hours each month.

In a scenario with extreme load shedding but a reasonable amount of generation capacity still online, critical infrastructure, which under new government proposals is an ever-expanding list, would still be supplied with electricity.

One way of Eskom getting to a more realistic Stage 16 schedule would be to slow the ramp from Stage 9 or Stage 11 onwards … Perhaps from this point, an additional 500MW of load would be cut per stage versus the existing 1 000MW ratchet?

Eskom has a few additional levers, including load curtailment (to large industrial customers) which runs separately.

Increasingly, this has the effect of making load shedding appear worse than the amount of demand being actively cut from the grid by Eskom.

Conradie conceded that last week Eskom had Stage 4 curtailment at the same time as Stage 6 load shedding, which explained the load reduction of 7 000MW during a number of evening peaks last week. (Eskom ought to have more clearly communicated this to prevent the media and commentariat on Twitter from jumping to conclusions.)

Eskom load shedding schedule for a region it services

Source: Eskom

* At this point, stages beyond Stage 8 are purely theoretical.

The reality is that once schedules pass Stage 8, four-hour blocks of rotational power cuts become six-hour ones. There are not enough hours in the day for any other result. And we know for certain that some higher stage of load shedding will see the timetables of Stage 4 and Stage 8 combined. This is simple maths.

Following the current Eskom methodology, this will be at Stage 12.

If this is the case, at that point electricity users will have no power for three quarters of the day.

Put differently, you will only have power for six hours each day (in three two-hour slots).

Let’s hope we never, ever get there …