HomeIndustry SectorsAsset MaintenanceThe Eskom Medupi coal-fired power plant rollercoaster ride

The Eskom Medupi coal-fired power plant rollercoaster ride

Scarcely a week after Eskom proudly announced the completion of its Medupi coal-fired power plant disaster struck.

This entire saga really has the makings of a Hollywood script, except we would probably be shown the door for making it completely unbelievable. Nevertheless, here goes. See if you can keep up.

First, let’s start with some background and technology information for readers unfamiliar with South Africa’s state-owned power utility project.

The Medupi power station project in Lephalale, in the verdant grasslands of the Limpopo Province, is a green-field, coal-fired power plant comprising six units rated in total at almost 4,800MW-installed capacity, owned and operated by Eskom.

The design does not include cooling towers, as the plant uses direct cooling technology. Other facilities include a coal stockpile, an ash dump and transmission lines that connect the power plant to the national electricity grid.

The plant is extensive, accommodating six boilers, and each boiler is powered by an 800MW turbine, while the units have 390 switchgear installed. Medupi incorporates super-critical technology, enabling it to operate at higher temperatures and pressures than Eskom’s previous generation plants.

With water scarcity and carbon emissions being a huge concern, the plant continuously monitors emissions and has zero-liquid effluent discharge.

While Eskom identifies Medupi as the fourth-largest coal-fired plant and largest dry-cooled power station globally, the project has had many setbacks and is billions of rand over budget.

That brings us into the now, when it appeared the rollercoaster ride of Medupi’s highs and lows were over as the final generating unit – Unit 1, the last of six generating units to be completed – attained commercial operation status and was handed over to Eskom’s generation division on Saturday 31 July 2021.

Read more:
Completion of Medupi coal power station announced by Eskom

In a statement, Eskom applauded the Medupi team, support teams and its execution partners for working tirelessly to ensure Unit 1 was handed over for commercial operation as planned by the end of July 2021. (Note completion of the first two units was initially expected by 2012 and the first was eventually completed in 2015, but … applause please).

The commercial operation status means technical compliance to statutory, safety and legal requirements have all been met. The unit was officially declared commercial after the completion of the unit optimisation, control demonstration, and the 72-hour and the 30-day reliability run, which have put all performance guarantees into effect.

However, eight days later, Eskom announces Medupi Power Station has experienced an explosion on the Unit 4 generator at approximately 22h50 on Sunday 8 August. The Eskom team also suspects the incident resulted in Unit 5 tripping.

Thankfully, no injuries were reported and all employees and contractors were accounted for.

Unit 4 was on a short-term outage (since 6 August) when the incident occurred, and all work on the unit was suspended with immediate effect. This included the suspension of all permits to work on the plant until further notice.

Beating Eskom to an official investigation into the cause of the incident, online speculation is already doing the rounds on social media.

Negligence, corruption, insufficiently skilled staff on site and the use of hydrogen, which is ideal for this type of plant, were cited. Some even went so far as to equate hydrogen safety with concerns over nuclear safety and waste disposal.

Energy analyst Chris Yelland explained via Twitter that he has it on “reliable authority that there was an internal hydrogen explosion within the 800MW generator” and that the incident occurred during the “activity to displace hydrogen with carbon dioxide and air respectively, for the purposes of finding an external leak”.

The preliminary investigation indicates that while performing this activity, air was introduced into the generator at a point where hydrogen was still present in the generator in sufficient quantities to create an explosive mixture, which ignited and resulted in the explosion.

It appears there was a deviation from the procedure for carrying out this activity. As such, Eskom has undertaken to place those employees responsible for managing and executing this work under precautionary suspension pending the conclusion of the Major Event Investigation.

Oh yes, dear reader, this really happened and we did not make this scenario up. We will keep an eye on further developments but welcome your take on how this will play out.

Until next week.

Editor, ESI Africa  

Nicolette Pombo-van Zyl
As the Editor of ESI Africa, my passion is on sustainability and placing African countries on the international stage. I take a keen interest in the trends shaping the power & water utility market along with the projects and local innovations making headline news. Watch my short weekly video on our YouTube channel ESIAfricaTV and speak with me on what has your attention.