Eskom’s recent success in boosting its power generation has led to an unexpected challenge: the grid now has more capacity than it needs, forcing the utility to take measures to maintain stability.

Power stations have been operating at an energy availability factor exceeding 70%, resulting in a fleet performance so strong that some units are being placed in cold reserve to prevent overloading the grid, says Bheki Nxumalo, Eskom’s Head of Generation.

“This is a far better problem to have than managing a highly volatile generation fleet that plunged South Africa into regular bouts of load shedding.”

Nxumalo credits the utility’s Generation Operational Recovery Plan for the turnaround, which was approved by the board in March 2023. The utility engaged in an intensive maintenance plan focusing on its coal-fired plants. “In particular, we focused on the six worst-performing power stations as they contributed to 70% of Eskom’s unit failure,” says Nxumalo.

The grid is now operating as it should, he points out. “This time last year, we were going through a very difficult time, as Eskom and as a country, so it is very encouraging that we can now operate in what is called ‘normal form’.”

The grid is operating with sufficient capacity to meet peak demand and handle fluctuations, an energy expert tells Energize. “Typically, the daily load on the network varies between 30 GW peak and about 20 GW minimum. Eskom has sufficient capacity to meet peak demand so has 10 GW spare at minimum demand. As it is not possible to ramp down the production of all stations, some have to be shut down and placed on standby.”

There are three levels of electricity generation:

• Baseline generation (running all the time)
• Mid-term generation (filling in the next level of demand)
• Plants managing peak demand

According to the energy expert, the current situation in South Africa is within mid-term generation. During the period when electricity demand is low, the stations are placed in cold standby so that they are not generating.