Ernest Wolmarans
2 minute read
26 Mar 2014
6:00 am

Power supply tight this week

Ernest Wolmarans

The national power grid remains at the mercy of unforeseen events as less than 800 megawatts separates supply from demand, Eskom said yesterday.

The Citizen's Kirsten Sekhaolelo works at The Citizen offices during a power blackout, 6 March 2014, in Industria West, Johannesburg. Electricity was cut across large parts of South Africa as state power utility Eskom cut power supply for the first time since April 2008. National load shedding started at 9am and would be rotational in two-hour sessions until 10pm on Thursday evening. Picture: Michel Bega

The system is expected to be constricted for the rest of the week.

“This depends on the system condition during the week, and can change based on events,” the power utility said in its bi-weekly system status bulletin.

Capacity available to meet Monday evening’s peak demand was forecast at 31 874 MW, including the use of hugely expensive open-cycle gas turbines, while demand was forecast at 31 085 MW.

Planned maintenance stood at 6 470 MW with unplanned outages, the thorn in Eskom’s side in the face of the current lack of sufficient generation capacity, at 4 551 MW.

It was a sudden leap in unplanned outages that resulted in load shedding recently, largely because wet coal reserves could not be fed through to power stations in Mpumalanga after persistent, heavy rains.

As of late yesterday morning, the system was in a state of “no load shedding”, Eskom’s website declared.

The utility was able to avoid load shedding last Tuesday when demand outpaced supply, through “extensive use of interruptible load supply”, part of which included the cutting of supply to neighbouring states.

Despite system stability hanging in the balance, the utility shut down Koeberg nuclear power station’s unit two on Sunday for refuelling, inspection and maintenance which accounted for 900 MW of the planned maintenance figure, Eskom said.

“The shutdown has been taken into account in relation to Eskom’s plans to keep the lights on, and is not expected to result in a shortage of supply to the Western Cape or the rest of the country.

“But it must be noted that taking 900 MW from a constrained system requires a concerted effort from all stakeholders to reduce electricity demand.”

Koeberg’s unit one continues to operate at full power.

Maintenance on the two units is done sequentially every 18 months or so to avoid both of them being out of service at the same time.

Tonight’s peak demand was forecast at 31 184 MW and was expected to trail off daily to just under 29 000 MW on Sunday.