Unit 6 at Kusile power station has officially entered into commercial operation, which Eskom says marks the end of its multi-decade build programme – one which experienced well-publicised delays, major cost overruns, and technical problems, alongside allegations of serious corruption that featured heavily at the Commission of Inquiry into State Capture.

Construction on the Mpumalanga coal-fired power station started in August 2008 and was initially expected to take six years to complete, while the project’s initial budget of about R80-billion subsequently swelled to above R233-billion.

In a statement, Eskom claimed that with Unit 6 online, Kusile and Medupi now had a combined 9 600 MW when operating at full capacity and that the two power stations would help strengthen electricity supply, which had stabilised recently following years of loadshedding.

This, after Medupi Unit 4 was reintroduced in July following a protracted repair. The unit had been out of service since August 8, 2021, after its generator stator was damaged in an explosion.

Located in the Limpopo province, Medupi is a similar mega-scale coal project to Kusile and was built largely in parallel to the Mpumalanga project.

However, Medupi has not yet included the flue gas desulphurisation (FGD) pollution control systems that have been integrated, with much difficulty, at Kusile.

The FGD system at three Kusile units was bypassed for 13 months to allow three units to resume operation using temporary stacks, after the Unit 1 flue duct collapsed because of an uncontrolled build-up of slurry on October 23, 2022.

The failure eliminated 2 100 MW of Kusile’s capacity from an already stretched system at the time, as the flues for units 2 and 3, which share a chimney with the Unit 1 flue, were also damaged by the collapse.

The plant is the first in Africa to employ wet FGD technology and Eskom is still assessing what FGD solution to fit at Medupi, in line with a World Bank loan stipulation.

Unit 6 has in fact been supplying electricity to the grid since its synchronisation on March 23, 2025, but Eskom said the declaration of commercial operation signalled that the unit had passed all required testing and optimisation phases and had been fully integrated into Eskom’s operational fleet.

“The successful commissioning of Unit 6 adds 800 MW to the grid and completes our twelve-unit megaprojects fleet,” group executive for generation Bheki Nxumalo said in a statement, while acknowledging the “many challenges along the way”.

All of Kusile’s units will now be officially recorded in Eskom’s energy availability factor (EAF), which has recovered strongly in recent months.

On September 26, Eskom reported a month-to-date EAF average of 71.15%, and stated that the last time it trended above 70% was in 2021.

CEO Dan Marokane said the Unit 6 milestone not only completed the Kusile build programme but also reinforced Eskom’s commitment to restoring energy security.

That said, he reiterated Eskom’s intention to invest in renewables, with a standalone unit in the process of being established to pursue such projects in partnership with the private sector.