Brace for lots of load shedding
43% OF CAPACITY: UNAVAILABLE, AND OUTLOOK IS DIRE So far for January, 23.9% of Eskom’s generation fleet is unavailable due to breakdowns.
Eskom’s official threemonth 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 1 000 megawatts (MW) and 2 000MW short to meet its reserve margin and “possibly demand”.
Using the assumption of a total of 12 000MW of breakdowns, its “planned risk” level is 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 2 000MW short.
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 748MW, nearly 3 000MW higher than its longterm assumption of 12 000MW used in its planning. It is these spikes in breakdowns that necessitate load shedding.
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 29 000MW of demand by using the following additional sources:
► 323MW of its own OCGTs from 10 units;
► 263MW of pumped water generation’
► Around 2 000MW of manual load reduction (load shedding;)
► 266MW of interruption of supply (IOS) to large customers.
It also utilised just less than 1 500MW of supply from renewable sources, primarily wind.
On Thursday night, its coal fleet was only producing 20 408MW of power. Contrast that with Monday night’s peak (7pm) where its coal fleet was producing 22 371MW, and one can easily see the huge problem.
Eskom’s generation issues have been compounded by it being forced to take unit one 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.
‘Non-commercial generation’ capacity
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.
Two of these units are set to achieve commercial operation in the next three months. By midApril, Eskom says it will have 43 858MW of dispatchable capacity from the roughly 40 000MW 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.
Chief executive Andre 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.