Load shedding: The short-term outlook is dire

Eskom’s official three-month outlook for demand and generating capacity shows a high likelihood of load shedding every single week until mid-April.

In fact, for six of the coming 13 weeks, it forecasts that it will “definitely” be between 1GW and 2GW short to meet its reserve margin and “possibly demand”.

Using the assumption of a total of 12GW of breakdowns, its “planned risk” level is effectively guaranteeing some load shedding in these weeks. In the second week of February, the worst of the coming 13 weeks, it is forecasting to be at least 2GW short to meet demand.

Eskom’s generation issues have been compounded by it being forced to take Unit 1 of Koeberg offline earlier than planned

This comes as the utility was forced to implement stage-2 load shedding from midday on Thursday as it lost four generation units (two at Kusile and one each at Kriel and Duvha). Beyond this, it had a further four units whose “return to service from planned maintenance” was “delayed”. This saw unplanned outages spike to 14.7GW, nearly 3GW higher than its long-term assumption of 12GW used in its planning. It is these spikes in breakdowns that necessitate load shedding.

Eskom announced on Sunday that load shedding would reduce to stage 1 from 11pm on Sunday to 5am on Monday, then resume at stage 2 until further notice. It said it would provide a further update on Monday.

Peaking

Typically, the utility is able to augment peak demand with its peaking power plants, either via pumped storage schemes or open cycle gas turbines (OCGTs), which burn diesel.

To meet the 7pm peak on Thursday (the highest in a while), it met around 29GW of demand by using the following additional sources:

1 323MW of its own OCGTs from 10 units;
1 263MW of pumped water generation;
Around 2GW of manual load reduction (load shedding);
266MW of interruption of supply (IOS) to large customers; it often calls this “virtual power station”;
It also utilised just less than 1.5GW of supply from renewable sources, primarily wind.

On Thursday night, its coal fleet was only producing 20.4GW of power. Contrast that with Monday night’s peak (7pm) where its coal fleet was producing 22.4GW, and one can easily see the huge problem.

Eskom’s generation issues have been compounded by it being forced to take Unit 1 of Koeberg offline earlier than planned for scheduled maintenance after “an increasing leak rate was observed on one of three steam generators”.

Originally, it was to take this unit offline for refuelling and routine maintenance in February. It expects the unit to “return to service during May 2021” meaning that a shortfall of this 900MW of dependable, baseload supply will persist until the start of winter.

In the first week of January, it relied on between 1 139MW and 1 445MW of so-called “non-commercial generation” capacity during each evening peak.

Because of the precarious generation picture, one can assume it is using some of these units (Kusile 2 and 3 and Medupi 1) throughout the day.

Critical to avoiding load shedding is the utility trying to keep unplanned breakdowns to below 12GW

Two of these units are set to achieve commercial operation in the next three months. By mid-April, Eskom says it will have 43.9GW of dispatchable capacity from the roughly 40GW currently. Still, with this increase in capacity it is still forecasting supply constraints, which means likely load shedding.

At this point, it can reduce the amount of planned maintenance by deferring certain work to give itself more headroom, but this is the primary reason it’s in this position to begin with. The utility has done too little maintenance for about a decade as successive executives focused on keeping the lights on at all costs.

Break the cycle

CEO André de Ruyter has been clear that he intends to break this cycle, as this is the only way that Eskom’s fleet reliability will improve over time.

At this stage, the amount of planned maintenance over the next three months remains at the level it forecast in the first week of January.

Critical to avoiding load shedding is the utility trying to keep unplanned breakdowns to below 12GW. However, because most of its coal fleet is old and unreliable, when units break down it has to run those units that are operating harder to try and boost supply. Often, this results in further trips and outages, which is why Eskom typically takes many days to recover from load shedding.

André de Ruyter

From Eskom’s own publicly available dashboard, a total of 43% of its capacity is unavailable due to breakdowns, planned maintenance, and “other outages” so far this month. This is the highest in at least two years.

There are however a few bright spots in this data.

So far for January, 23.9% of Eskom’s generation fleet is unavailable due to breakdowns. This sounds high – it is – but it is significantly lower than the 27.9% of unplanned outages across the fleet in January last year and 29.2% in February 2020. Additionally, Eskom is doing 50% more planned maintenance this January (15.3% of its fleet so far this month, versus 10.3% in 2020). Since September, this number has been 13% or higher (as much as 17.6% in December), compared to 2019 where maintenance barely exceeded 10% of capacity for much of the year.

This is a very good sign.