Eskom’s coal-fired power stations in deep trouble

New data from energy expert Clyde Mallinson revealed that Eskom’s energy availability factor (EAF) for its coal fleet dropped to 46% in 2023.

Mallinson is a director at Virtual Energy and Power and Clean Energy Projects and a regular commentator about South Africa’s electricity problems.

He published a chart of Eskom fleet and coal fleet energy availability factor up to week 9 for 2023.

It revealed that, for 2023 year-to-date, the EAF for the whole fleet is 52%. However, the EAF for Eskom’s coal fleet is only 45.64%.

Eskom’s coal fleet had a capacity factor of 45.2% during this period, which Mallinson said means that all available coal units are being utilised at close to 100%.

The data shared by Mallinson revealed a rapidly declining energy availability factor without any signs of a quick turnaround.

It shows that Eskom’s turnaround journey to improve plant performance and reduce load-shedding is failing.

When the new Eskom board was appointed last year, Public Enterprises Minister Pravin Gordhan gave it the mandate to increase the energy availability factor (EAF) to 75%.

22 January 2023, Eskom chair Mpho Makwana said it would take two years “to improve the EAF from the current 58% to 70%”.

“The turnaround journey will see a stretch target EAF being driven toward 60% EAF by 31 March 2023, a mere ten weeks away, then 65% EAF by 31 March 2024 and 70% by 31 March 2025.”

Fast forward seven weeks, and there has not been any improvement in Eskom’s energy availability factor. In fact, it has significantly deteriorated.

Over the last few weeks, the downward trend in Eskom’s EAF continued unabated without any signs of increasing.

Eskom fleet and coal fleet energy availability factors (EAF), courtesy of Clyde Mallinson

It should not come as a surprise as many energy experts have warned that increasing the EAF is not trivial.

Professor Anton Eberhard from the University of Cape Town said it is very hard to turn the EAF around unless there is more spare generation capacity.

“Bringing back four damaged units at Kusile, one at Medupi, and a Koeberg nuclear unit will help but it won’t be enough,” he said.

He added that former Eskom CEO Andre de Ruyter highlighted the need for massive new generation investment but was crucified for his comments.

Energy analyst Chris Yelland explained that the energy availability factor is on a declining downward trend, which has been so for the past five years.

The EAF is based on the average performance of 90 generators in Eskom’s electricity generation fleet. “You cannot maintain or fix them simultaneously,” he said.

What this means, mathematically, is that the EAF is a continuum. There cannot be a discontinuity – also known as a step change – in the EAF trend.

“To increase Eskom’s EAF, there must first be a slowdown. It then has to bottom out, stabilise, and start to rise. This process will take several years,” he said.

“It is mathematically impossible for this to happen in the 2023/2024 or 2024/2025 financial years,” Yelland said.

“Talk of a 70% or 75% energy availability factor is misleading the public, and it is not achievable by Eskom.”


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