It is not clear publicly just how bad the picture is across Eskom’s aging coal power station fleet. Strong indications are that things are bad.

The utility has not published a weekly system status report since the beginning of October and its public data portal has not been updated since last Wednesday.

It says there has been a “fairly significant failure of the data support system” but that this “will be resolved soon”. It is unclear whether this and the failure to update its weekly system status reports are related.

What we do know is that Eskom is currently barely managing to generate 26GW of power to meet peak demand in the evenings.

Factoring in the contribution from renewable generation at the peak, there remains a shortfall of between 3GW and 4GW to meet demand.

To avoid stage-4 load shedding this week — where 4GW of demand is removed — it is relying on most of its 14 open cycle gas turbine (OCGT) peaking plants and is cutting supply to its large industrial customers, including South 32’s aluminium smelters near Richards Bay. On Monday, it removed 1.2GW of supply to these customers.

Eskom implemented stage-2 load shedding from Friday, 8 October. At that point, it said this would be until Thursday, 14 October at 5am. However, generating capacity has not improved materially since then.

Problematic

Its 14 OCGT plants can generate up to 2.1GW of power. So far this week, it has been supplementing its baseload generation capacity at peak with as much as 1.8GW from these plants.

When one removes the additional sources of generating capacity, in other words everything except coal, the picture starts to look problematic:

Peak generation capacity: ±26GW
OCGTs: ±1.8GW
Nuclear generation: 1.8GW
International imports: ±1.2GW (Cahora Bassa hydroelectric)

Imports were halved last Friday as maintenance started at Cahora Bassa. This will be restored to full capacity of around 1.2GW on Friday morning, 15 October.

It is not clear how much of its pumped water generation capacity it is using at the moment, but it is highly likely that it is using these schemes to provide between 1.5GW and 2GW of power in the evenings (never mind using these to stave off a higher level of load shedding during the day).

This means its coal fleet is producing no more than 20GW of electricity at the peak. The number is more than likely around 19GW.

Eskom says its installed capacity is 48.6GW. This includes non-commercial units at Kusile (likely two of the outstanding three). Remove Koeberg, OCGTs and imports from this capacity, and you are left with around 41GW of coal capacity. This means more than 50% of Eskom’s coal fleet is offline.

On Wednesday afternoon, the utility announced the suspension of load shedding from 5am on Thursday, as planned, but cautioned that “there are still significant risks to some generating units, which would force Eskom to implement load shedding at short notice should we lose any further generation capacity”.

Last week, it said there had been breakdowns of generating units at Kriel, Tutuka, Grootvlei, Kendal, Kusile, Komati and Hendrina power stations.

It said “while still recovering four units at Tutuka, which had experienced conveyor belt failures, the fleet suffered a cluster of boiler tube leaks within a short period of time”.

There are still significant risks to some generating units, which would force Eskom to implement load shedding at short notice

Certain of these units will likely have already returned to service, but based on the peak generating capacity picture shared each evening, it is equally likely that other plants suffered breakdowns.

It says it expects units to return to service at Kriel, Majuba, Hendrina, Lethabo and Tutuka power stations overnight and over the next few days.

It says total breakdowns amount to 14.9GW of capacity, with planned maintenance at 5.3GW. These figures are virtually identical to the data shared on Friday night (15GW and 5.3GW). The explosion at Unit 4 at Medupi in August, which has left 800MW of capacity out of service for what is expected to be the next two years, is included in the planned maintenance figure.

CEO André de Ruyter told eNCA on Wednesday that the utility is working to avoid load shedding as the country heads into election season.