Eskom burning billions

Eskom’s data portal shows that the power utility consumed much more diesel in early 2025 than it did over the same period last year.

From 1 to 24 April 2025, Eskom generated 378.9 gigawatt-hours of electricity with diesel-powered open-cycle gas turbines (OCGTs), roughly 69% more than in April 2024.

If it continues generating an average of 15.79GWh per day with OCGTs until the end of April, Eskom will have generated 473GWh of electricity with the diesel-powered plants, more than in any month last year.

Eskom’s OCGT usage has been on the rise since the start of 2025.

In the first three months of 2025, the power utility generated 1,666.9GWh of electricity with OCGTs, working out to a monthly average of 555.6GWh.

The diesel used to run the OCGTs in March 2025 cost Eskom an estimated R3.6 billion. For just the first 10 days of April, the diesel bill would have stood at R1.34 billion.

While Eskom has defended the strategic use of OCGTs as necessary to ensure it can conduct intensified planned maintenance, this practice has been criticised as “financial recklessness.”

According to Eskom’s 2024 data, it costs about R6,579 to generate a megawatt-hour (MWh) of electricity with OCGTs.

That compares with a much cheaper R541 or R113 per MWh of coal or nuclear generation, respectively.

1,000MWh is equal to one GWh, which means that a 1GWh of OCGT power costs about R6.579 million to generate.

Multiply that by the 2,045GWh generated with OCGTs in the year to date, and the estimated cost of the diesel used in 2025 is R13.45 billion.

For reference, the power utility spent R10 billion on OCGT diesel in the last nine months of 2024.

The chart below shows Eskom’s monthly OCGT generation for the 2024 financial year (including January to March 2025) and the 2025 financial year-to-date.

An unspoken factor?

The increased OCGT reliance is a concerning deviation from 2024, when Eskom drastically reduced OCGT usage.

There may be an unspoken factor influencing OCGT reliance in recent months — the weather.

The rapid adoption of privately-installed rooftop solar took substantial demand off Eskom’s fleet in 2024, especially during the middle of the day when irradiance levels were higher.

System Operator general manager Isabel Fick explained it enabled the power utility to fill up its emergency generation reserves — including OCGTs — so that Eskom could more regularly meet peak demand.

For several years before 2024, Eskom needed to use OCGTs for a larger part of the day, which resulted in reserves being depleted — often late in the work week or at the start of the weekend.

To replenish diesel for OCGT and water levels for pumped storage schemes, it often implemented higher levels of load-shedding over weekends.

However, the province with the highest private solar capacity — Gauteng — has been experiencing prolonged periods of inclement weather and above normal rainfall.

With less solar generation, households and businesses in the province have likely increased their reliance on grid energy,

The good news is that solar production is relatively flat in Gauteng and its adjacent provinces throughout the year.

While days are shorter in the winter, the climate is drier with less cloud cover than in the summer. That results in more stable and reliable production, apart from the rare wet and cold spells.

The south-western parts of the country, including the Western Cape, experience significantly reduced solar production during the winter.

However, the South African Weather Service expects the region to have a drier winter than usual, which could also benefit solar generation.