Eskom’s Power Surge: Improved Fleet Performance Leads to Excess Capacity

Eskom, South Africa’s state-owned electricity provider, has seen a significant improvement in its power generation fleet’s performance, leading to excess capacity. As a result, the utility is placing some of its units on cold reserve, a strategic move that saves money and resources while ensuring a reliable power supply. Eskom’s power generation fleet is currently performing so well that the utility is switching off certain units due to excess capacity, according to a recent report from Sunday Times. Bheki Nxumalo, Eskom’s head of generation, highlighted that the company is strategically placing some of its generating units on cold reserve when capacity significantly exceeds demand. This is part of a broader strategy to manage resources efficiently and maintain financial prudence.

Cold reserve involves temporarily shutting down the most expensive units to operate, typically the older power stations. Nxumalo emphasized that while these shutdowns help save costs, the reliability of bringing these units back online must be carefully considered. The process is normal for large, interconnected power systems and involves meticulous planning. Eskom forecasts electricity demand for every hour of every day up to 18 months in advance, allowing them to plan maintenance and shutdowns during periods of lower demand.

Restarting these units is no small task, as it can take up to 72 hours, so Eskom avoids placing too many units on cold reserve simultaneously. This careful approach ensures there’s enough power available to restart the generators when needed.

In the last week of July, Eskom’s daily production surpassed 35,000MW, about 3,000MW higher than the peak demand. This marked the first time since July 2018 that the utility had achieved such high generation figures. Nxumalo attributed this success to Eskom’s decision to focus on repairing its existing generation fleet rather than investing in new capacity. He noted that capacity losses had dropped to below 9,000MW, about 7,000MW less than the same period in 2023. The cost of fixing the current fleet was significantly lower than the estimated R100 billion needed to add the same capacity through new projects.

The improvement has also been seen in Eskom’s most problematic power stations, Medupi and Kusile, which have now become the top performers in the fleet. “We had some teething issues during the start-up, but now those stations are performing exceptionally well,” said Nxumalo.

Experts like Professor Sampson Mamphweli from the South African National Energy Development Institute are optimistic about the future, suggesting that load-shedding could be a thing of the past by the end of the year. This optimism is based on the improved energy availability factor, fewer breakdowns, and reduced demand. Mamphweli believes that if Eskom can maintain this trend through the start of summer, load-shedding may be officially declared over by the government between November and December 2024.

Electricity and Energy Minister Kgosientsho Ramokgopa echoed this sentiment, noting that Eskom’s improved performance has sustained a break from extensive load-shedding since 26 March 2024. He also emphasized that the upward trend in plant availability, coupled with decreased unplanned losses, indicates that this performance is sustainable. Additionally, the government is working on complementing the coal fleet with new generation capacity, including converting open-cycle gas turbines from diesel to gas and from open to closed-cycle systems.

As Eskom heads into the summer of 2024, its generation fleet is performing more reliably than it did during the same period in 2023. The utility has managed to keep unplanned losses below 14,000MW throughout the winter, while also using the improved performance to conduct additional short-term planned maintenance.