Explosion at South African power plant

AN explosion at a power station in South Africa has caused extensive damage to the facility’s generator, leaving two units offline and reportedly threatening supply and demand.

No injuries were reported, and all contractors and employees were accounted for. However, seven employees were treated for shock.

The blast occurred at the Medupi power station at around 22:50 local time on 8 August. Belonging to state-owned electricity utility Eskom, the recently-completed 4,764 MW plant is located west of Lephalale, in Limpopo Province, South Africa.

A preliminary investigation revealed that the explosion was triggered while workers were purging hydrogen from the plant’s generator using carbon dioxide and air, as they worked to find an external leak. Air was introduced while hydrogen was still present at sufficient quantities to create an explosive mixture, which then ignited. The unit was on a short-term outage at the time, which began on 6 August.

In addition, the investigation has discovered that there was a deviation from procedure during the activity.

Eskom has suspended the employees that were managing and executing the activity, pending conclusion of the investigation. Additionally, work on the unit has been suspended, as well as permits to work on the plant.

The ongoing investigation aims to identify the cause of the incident, as well as the extent of the impact it will have on the national electricity grid. The company has revealed that following the explosion at Unit 4, Unit 5 tripped, which the company expects was due to the incident. This leaves two of Medupi’s six units offline.

As of its last update about the incident, on 9 August, Eskom was working to return Unit 5 to service. Eskom has yet to update on electricity grid impact.

Independent energy analyst Chris Yelland, speaking to South African news organisation Moneyweb, said that a combination of high levels of unplanned outages that the company is experiencing and planned maintenance means that supply and demand are quite tight. He notes that the loss of a unit’s capacity could worsen the situation.

Yelland also said that the explosion serves as yet another setback for the Medupi power plant. According to Yelland, the plant – for which construction began in 2007 – was meant to be complete by the end of 2014.

Completion was only recently announced on 2 August 2021.

Additionally, even as Eskom announced completion, Power Station Manager Bheki Nxumalo acknowledged repairs related to boiler design defects that would be to be carried out over the next 24 months. At the same time, the company stated that it had spent R122bn (US$8.15bn) on the project to that point and expected to spend a further R135bn on completion of balance of plant.

Yelland told Moneyweb that “significant re-work” is required to resolve design as well as execution defects.