Truth about Eskom’s diesel usage during longest load-shedding break in two years

Eskom has not consumed excessive amounts of diesel in its open-cycle gas turbines (OCGTs) to avoid implementing load-shedding during April 2024.

As of 29 April 2024, there had been no load-shedding for over 34 days.

According to load-shedding tracking app EskomSePush and independent data-focused publication The Outlier, this has been the longest consecutive break in power cuts since the nearly two-month reprieve in December 2021 and January 2022.

This has raised suspicions among many South Africans that the power utility was running its power stations and OCGTs in overdrive to benefit the ANC ahead of the national and provincial elections on 29 May 2024.

While Eskom has recorded commendable improvements in breakdowns, its overall energy availability factor (EAF) has only shown marginal improvements due to ramped-up maintenance.

In its latest State of the System briefing on Friday, 26 April 2024, Eskom shared its expenditure on diesel to run OCGTs over the past two months and compared this with usage over six months in 2023.

This showed Eskom had spent R3.1 billion on OCGT fuel during March 2024, which had 26 days with load-shedding.

This is R1 billion more than the power utility spent the same month a year ago, when it had 30 days with load-shedding.

However, in the first three weeks of April 2024, which had no power cuts, Eskom had spent R1.35 billion on diesel.

If Eskom’s average fuel consumption in the last week of April is the same as in the first three weeks of the month, it will spend about R1.74 billion on all four weeks.

With a more pessimistic R0.81 billion in weekly diesel expenditure like in March 2024, the amount increases to R2.21 billion,

That would still be substantially less than the R3.1 billion it spent on diesel in April 2023, which had no days without load-shedding.

The chart and accompanying data below show various key generation performance factors and Eskom’s OCGT expenditure for six months in 2023 and March and April in 2024.

Eskom System Operator Isabel Fick offered one of the best and clearest explanations as to why diesel usage has decreased alongside a reduction in load-shedding.

Fick said the big increase in private photovoltaic (PV) solar had taken a significant strain off Eskom’s system during periods with sunshine.

Eskom estimated there was around 2,800MW of PV solar directly connected to the grid, with another 5,440MW when including “behind-the-meter” solar.

This has enabled Eskom to better replenish its emergency generation reserves like OCGTs and pumped storage dams for use during peak periods.

Fick also explained that the OCGT usage in March 2024 was so exceptionally high because there were more days with inclement weather during that month.

This meant solar’s overall contribution was lower than in April 2024, and Eskom had to rely more on its emergency generation reserves during the day.

While winter offers fewer hours of sunshine, the northern parts of the country — including Gauteng — experience less overcast weather during this season.

Therefore, solar will likely continue playing a key role in reducing load-shedding risk during the winter.

The table below from Eskom shows how much private PV solar it estimated was installed in South Africa from July 2022 to March 2024.