The inconvenient truth about Eskom’s Kusile power station

At least there is finally a credible plan.

The National Energy Crisis Committee (Necom) intends to recover and add 8 800 megawatts (MW) of generating capacity this year in an effort to reduce the intensity of load shedding.

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There are eight interventions in 2023:

• Bring Kusile units 1, 2 and 3 back online, plus achieve commercial operation for Unit 5 (2 880MW);
• Additional imports from neighbours (up to another 1 325MW);
• An emergency generation programme and a standard offer from Eskom to buy excess capacity from commercial/industrial customers (1 000MW);
• Utility-scale private embedded generation projects (up to 1 600MW);
• Using feed-in tariffs to unlock supply from commercial and household rooftop solar (850MW);
• Ramp up demand-side and energy efficiency programmes to cut demand (250MW);
• Complete first phase of Eskom’s battery energy storage system (200MW); and
• Contract surplus supply from existing renewable producers (70MW).

What is immediately clear from this plan is just how much is riding on Kusile – Eskom’s brand-new but not-yet-finished power station, with a price tag of R161 billion (let’s be honest, the final cost will be higher; that’s just how these projects go!).

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To get the three already-completed Kusile units back after October’s chimney collapse would, according to government’s plan, magically add around 2 000MW of generation capacity, equivalent to two stages of load shedding.

So, with these Kusile units back, the theory is that instead of, for example, Stage 4 load shedding, Eskom would only need to implement Stage 2.

Last month, in that hastily convened media conference on a Sunday morning, Eskom provided additional details about the Kusile Unit 1 flue duct failure that happened on 23 October.

The duct bend collapsed due to the “excessive weight of slurry” (ash and water). Eskom contends that this was “owing to design defects in the boiler, and subsequent adverse operating conditions in the flue gas desulphurisation unit (FGD)”. The unit was not operating at the time.

This accident should never have happened. There should not have been that much ash build-up and slurry in the duct.

This ‘failure’ (read: collapse) “compromised the adjacent flue duct bends” of Units 2 and 3, “making all three units inoperable”.

This, Eskom says, removed 2 160MW from the power system – equivalent to two stages of load shedding.

The plan is to build temporary flues for these three units to allow repairs to the main chimney, which is shared by all three units. According to Eskom, this will take between 10 and 12 months. It will take 10 months for the first temporary stack to be built, with the remaining two being completed in one-month intervals.

Importantly, Eskom needs to be granted an exemption from the Department of Forestry, Fisheries and the Environment to allow it to operate these units “while bypassing the FGDs”. Translated, this means Eskom needs to be allowed to emit more than double the amount of sulphur dioxide (1 000mg/Nm³) than it would ordinarily be (500mg/Nm³). Kusile is the only Eskom plant fitted with FGDs.

Noxious emissions aside, Eskom says we “can expect the three units towards the end of the year”.

Bigger picture

Its overall plan sees 6 274MW in capacity being recovered in total from five key power stations (Tutuka, Kendal, Duvha, Majuba and Matla) along with the return of Medupi Unit 4 (which exploded in August 2021) and the completion of Kusile units 5 and 6.

The three Kusile units aren’t factored in because, as Eskom politely describes it, they “failed after the plan was developed”. Recovering the Kusile units will therefore allow Eskom to get back to where it had expected to be.

Sure, load shedding is currently worse than it would’ve been due to the Kusile chimney collapse.

But the presumption that the full 2 160MW generating capacity from these units would be available is simply inaccurate. (Never mind that all Kusile – and Medupi – units are operating at 720MW, below their nameplate capacity of 800MW.)

The inescapable truth is that Kusile has consistently been one of Eskom’s worst-performing power stations.

It sits just outside the five stations that account for more than half (55%) of the unplanned load losses across its fleet. Until October, these stations contributed around 8 600MW of the average generation losses.

In a written response to questions from Moneyweb, Eskom confirmed in November that the energy availability factor (EAF) for the four commercial units at Kusile was 45.7% year to date.

This included a two-week period where units 1, 2 and 3 were offline due to the aforementioned flue collapse. Still, this is not a long enough period to have impacted this figure by a massive amount (two weeks out of 32). Plus, while these units were offline, unit four was still online – hence EAF was not 0%.

Eskom told Moneyweb that “the duct incident has effectively rendered on average 1 500MW of generation unavailable from the grid in the short term”.

This is a brand-new power plant! One which, Eskom has admitted, will never be able to produce at the 800MW nameplate capacity per unit.

Already, this has been adjusted down in all planning to 720MW. The reality is these units are not even consistently achieving that level of output.

And crucially, 1 500MW (the amount being produced on average from the three units) is not equal to 2 160MW (which the plan assumes will come back on stream).

There remains hard work ahead to turn the performance at this (brand new) power station around.

There is reason to be hopeful: Medupi’s problems are largely behind it and three of its units are operating at an energy availability factor of close to 90%. This can be done.

It goes without saying that Eskom should absolutely be recovering this lost generating capacity at Kusile as quickly as possible. But to assume that it’ll magically be fully and consistently available is optimistic in the extreme.

This article originally appeared on Moneyweb and was republished with permission.
Read the original article here.

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