Kusile units could start generating again in October

At least one of the three units at Kusile power station in Mpumalanga that have been offline for almost a year could start generating electricity in October, almost two months sooner than expected.

The shutdown occurred in October 2022 after a flue gas desulphurisation duct, which carries emissions from unit 1 into a large chimney, collapsed under the weight of ash build-up inside the pipe. The chimney also houses the flue gas ducts for units 2 and 3. As a result all three units — with a combined generation capacity of about 2,400MW — had to be shut down, contributing to two full stages of load-shedding.

Eskom initially expected a temporary fix for the three units — that would reintroduce them to the grid while permanent repairs are undertaken — would be completed by December 24.

However, Eskom’s head of generation Bheki Nxumalo, said Tuesday the units could start returning next month.

The earlier completion date will give state-owned power company greater room to increase overall maintenance without higher stages of load-shedding.

Nxumalo said once the three units at Kusile have been returned to service they are expected to run at full capacity.

Eskom almost doubled the amount of power taken offline for planned repairs this week compared with May, June and July as part of its summer maintenance plan.

This increase in maintenance outages was partly to blame for Eskom implementing stage 6 load-shedding this week. The situation was worsened by unplanned breakdowns, which increased from about 14,500MW on Friday to about 17,200MW on Tuesday after multiple unit failures some of the worst-performing power stations — Kendal, Kriel and Tutuka.

Eskom’s target is to keep unplanned breakdowns at less than 15,000MW.

Electricity Minister Kgosientsho Ramokgopa said on Tuesday Eskom had taken about 6,000MW out of service (compared with about 3,000MW during the winter months) for routine maintenance. While the company was aware of the impact of higher stages of load-shedding on the economy, the risk posed by delaying essential maintenance was even greater, he said.

The previous lack of maintenance on the group’s ageing coal-fired plants were contributing to the high number of unplanned breakdowns at present, Ramokgopa said. “We are going to do things right to avoid what has happened in the past which got us to where we are today,” he added.

Increasing maintenance now would “introduce greater levels of resilience and greater levels of confidence” that generation units would perform reliably and in line with their design capacity when they return to service.

Generation performance data published by Eskom show planned maintenance was slightly higher during April, May, June, July and August compared with the same months last year. In September 2022, roughly 11.5% of its total installed generation capacity was taken offline for maintenance compared with 13.5% during the first week of September this year.

However, the data also shows a marked increase in unplanned losses. For the five months to end-August 2022 an average of about 30% of generation capacity was unavailable due to unplanned outages. For this same period this year about 34.5% was unavailable because of breakdowns.

Nxumalo said the deterioration in performance was largely due to the failure of the three Kusile units as well as the several delays in maintenance at Koeberg unit 1.

“Our focus is on getting the Kusile units back online,” Nxumalo said. “This will provide valuable reserves. The initial plan was to return those units in December; we will now return the first unit in October, which will help reduce [unplanned losses].”

Eskom should be able to reduce load-shedding from stage 6 towards the end of this week with the planned return of generation units at Medupi and Tutuka, he said.

erasmusd@businesslive.co.za