Major Eskom turnaround milestone

Eskom has improved its coal power station fleet’s weekly energy availability factor (EAF) to 60% for the first time in more than a year.

That is according to Eskom generation manager Eric Shumugam, speaking at the Minister of Electricity’s update on government’s energy action plan on Monday, 23 October 2023.

“I can confirm last week [16 to 22 October 2023], we reached 60% in the weekly EAF,” Shumagam said. “If you look at the last three weeks, we’ve trended from 57 to 60%.”

The EAF is a percentage figure indicating what proportion of Eskom’s installed nominal capacity is available to deliver power to the grid.

It is used as an overall measurement of the performance of Eskom’s coal power fleet.

The last time Eskom’s coal fleet had an average weekly EAF above 60% was in week 34 of last year — from 22 to 28 August 2023.

Shumagam said that the improvement has helped Eskom reduce its open-cycle gas turbine (OCGT) usage, which was good news for the utility’s budget.

These power stations burn diesel to generate gas that can spin turbines to generate electricity.

Gourikwa open-cycle gas turbine power station (OCGT)

While this makes them much more expensive than coal power stations, they are critical in avoiding higher states of load-shedding, which come at a greater cost to the economy,

Previously, the OCGTs were intended only to be used during emergency shortfalls.

But with Eskom’s coal power fleet in a dire state, the OCGTs have been running more frequently — even during peak periods over weekends, which generally have much less demand.

However, Eskom’s evening peak demand statistics showed it did not need to run its OCGTs for evening peak periods last week, despite only implementing up to stage 2 load-shedding.

Shumagam added that the OCGTs will nonetheless continue to be required for some evening and early morning peak periods.

EAF still far short of target

Energy expert Chris Yelland praised Eskom for improving the EAF in the week before last, when it had already climbed to 58.83%.

This was Eskom’s best performance in the current calendar year and higher than in the same weeks in 2021 and 2022.

However, the average weekly EAF over the calendar year is still well below previous years. As of Week 41 of 2023, it stood at 54.71%.

At the same time in 2022, the EAF for the calendar year was 59.18%. In 2021, it was around 62% by Week 41.

The graph below from Chris Yelland shows how Eskom’s EAF changed week-on-week in 2021, 2022, and 2023.

The Eskom board’s EAF target of 65% for the 2023/2024 financial year might still be a bridge too far — as many sceptics feared.

The fleet’s performance will have to be substantially better over the next five months than it has been over the same period in the past few years if there is any hope of achieving this.

Even in 2021, when the fleet performed better on average, Eskom failed to hit anywhere near a 65% EAF over that period.

The biggest contributor to the recent improvements in Eskom’s generating capacity is the return to service of Kusile Unit 1 and Unit 3, which provide combined maximum capacity of 1,600MW.

Together with Unit 2, the units had been offline for nearly a year due to the collapse of a flue-gas duct in October 2022.

Eskom was only allowed to bring the units back online because it was granted an emissions exemption while conducting a complete repair of the flue-gas desulphurisation system.

Kusile Power Station near Emalahleni in Mpumalanga.

Kusile Unit 2 is also scheduled to return to service by the end of November 2022, further bolstering Eskom’s EAF.

As a result of the improved EAF, Eskom has been able to implement substantially less load-shedding in the past few weeks than throughout much of the year.

Minister of Electricity Kgosientsho Ramokgopa repeated his view in recent weeks that the country has turned a corner when it comes to reducing load-shedding.

He commended Eskom generation head Bheki Nxumalo and power station managers for the improvements, but acknowledged the utility was not yet out of the woods.

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Major Eskom turnaround milestone