Dominic Goncalves, Energy Strategy Advisory Partner at Cresco Project Finance (Photo provided)
Diesel, long considered South Africa’s last line of defense during power outages, can no longer be taken for granted, an energy expert warns, amid the continued disruption of global fuel supplies.
Dominic Goncalves, consulting partner for energy strategy at Cresco Project Finance, says major energy consumers, domestically and internationally, are faced with a new reality.
“Diesel, which has always been the backbone of emergency power, can no longer be considered reliable when the power grid fails or during a power crisis,” says Goncalves.
According to him, the availability of diesel during crises was rarely questioned until recently.
“When South Africa’s power goes out, diesel keeps the country going,” he explains.
In normal circumstances, Eskom’s open cycle gas turbines (OCGT) use only a small part of the country’s diesel supply to balance the system. During crises, however, this consumption increases sharply.
During previous severe load shedding periods, Eskom’s diesel consumption rose from around 3% to 10% of national demand to between 20% and 30% to limit load shedding.
At the same time, private users, including hospitals, data centers, industries and households, rely on generators when the power grid fails.
Eskom’s balance is currently stable – but risk remains
Open cycle gas turbines (Photo: Eskom)
Goncalves says Eskom currently maintains a relatively stable power grid despite an aging fleet.
However, he warns that around 17.7 GW of coal capacity will be decommissioned by 2035 – around 40% of the current capacity – without sufficient replacement capacity.
According to Cresco’s models, load shedding may again occur regularly from 2029.
Although there is currently around 4.8 GW of reserve capacity before load shedding becomes necessary, a combination of unexpected problems can quickly change the picture.
“An unlikely but possible scenario where several generating units go out of service at the same time, together with smaller problems such as leaks at boilers, could plunge South Africa into load shedding again within days,” warns Goncalves.
He points out that such incidents are not uncommon. For example, a recent incident resulted in the loss of more than 4 GW of capacity when several units at different power stations went out of service at the same time.
Hormuz crisis exacerbates risk
The current disruption of global fuel supplies due to the conflict around the Strait of Hormuz significantly increases the risk.
“If diesel supplies are limited, Eskom will struggle to use the OCGTs as usual to avoid or reduce load shedding,” says Goncalves.
He adds that the country’s security buffer is therefore smaller than previously assumed.
“If such a crisis coincides with a load-shedding event, Eskom and private users cannot obtain enough diesel.”
Goncalves believes that the energy industry must quickly adapt to this new reality.
“Energy experts now realize that diesel is no longer the last line of defense. Solar power and batteries can provide some resilience by reducing diesel consumption, but without it, the power could simply run out during a prolonged crisis.”
