150711. Sunset in Crownmines, Johannesburg. The picture can be used for Eskom energy supply crisis. Picture: Dumisani Sibeko

Johannesburg - The tripping of four more of Eskom’s generating units almost plunged South Africa back into darkness yesterday. The electricity reserve was depleted when the utility declared a supply emergency at 2pm.

Just a day before, Eskom had said the country was not in a situation similar to November 19 last year when it adopted the same emergency protocol.

“In the next chapter of these unfolding events, the tripping of these four generators at the back of [Wednesday’s] situation put us in a vulnerable position,” Eskom spokesman Andrew Etzinger said.

Three of the four units tripped because of boiler tube leaks, while Eskom was still investigating the reason for the tripping of the fourth boiler. This resulted in unplanned outages climbing to 7 000 megawatts (MW) of capacity.

A week ago, Eskom’s unplanned outages were just below 4 000MW, which meant it lost capacity of an entire power station due to technical problems this week.

Although it said the emergency was in force only until 9pm yesterday, to lift the emergency status, it needed to have 1 700MW more electricity during the peak period.

Etzinger said it expected two of its generating units to come back to service later to meet demand. While these had the capacity to produce 800MW combined, the problem was that units did not come back to full capacity immediately so Eskom would have to rely on its industrial customers’ willingness to reduce their electricity usage.

“In November, when we adopted a similar protocol, there was a good response from our big industrial customers. We contacted each of them directly and I’m confident they’ll support us again,” he said.

About 140 of Eskom’s biggest customers including mines, smelters, refineries and other manufacturers, received the request to reduce consumption by 10 percent. Even commercial customers in shopping centres and retail outlets were asked to use electricity sparingly by switching off geysers and adjusting air-conditioning temperature levels to 23ºC.

Eskom said it would make every effort to avoid load shedding. But even if lifted, chances this emergency status would recur remain great this year until the integration of Medupi’s first unit into the grid.

Etzinger said Unit 6 would be commissioned well before the end of the year but as it depended on contractors’ performance, it could be any time in the second half of the year.

Yesterday’s crisis prompted the Energy Intensive Users Group to express its concerns that Eskom targeted only industrial customers to reduce power consumption and it called for solutions to address underlying issues. “Extended periods of load shedding can lead to economic decline; you cannot have a smelting plant off for long periods,” spokesman Shaun Nel said.

Some mining companies said production would be affected after Eskom’s requests to reduce consumption. In mid-November many mines cut two hours out of their working day.

“The reduction will have an impact on our production. We are unable to quantify the extent. However, we have contingency plans in place to address this,” said Patrick Wadula, a spokesman for BHP Billiton, which operates the Bayside and Hillside aluminium smelters in Richards Bay.

ArcelorMittal South Africa, the country’s biggest steel producer, said there would be some impact on production but could not quantify it.

A spokesman for Gold Fields’ South Deep mine in Gauteng on Wednesday said it had operated at a minimum load between 5pm and 8pm following a request by Eskom. At AngloGold Ashanti, all operations reduced non-essential loads from 5pm to 9pm, but would resume normal load profiles for the night shift, a spokesperson said. Some Anglo American operations reduced electricity usage in terms of their operating levels. - Business Report