State-owned electricity producer Eskom said it was not anticipating any need to introduce load shedding on Tuesday, having avoided load shedding on Monday.

In a system update, the utility also reported that the risk of rotational load shedding had reduced “significantly and the prognosis for the week is better than expected”.

This was partly attributed to a better-than-expected recovery at the Majuba power station, in Mpumalanga, where a coal silo collapse on Saturday had precipitated the first load-shedding incident of the new summer maintenance season. It was the second load-shedding incident of 2014, however, with rotational shedding having also been implemented on March 6. The March event, which was caused by coal delivery problems, was the first since 2008.

The collapse of the central silo at Majuba, which occurred at 13:12 on November 1, resulted in output falling from over 3 000 MW to only 600 MW by Sunday.

Eskom instituted stage-two load shedding of more than 1 000 MW on November 2 to stabilise the system and restore reserves ahead of the business week.

Coal feeder units that bypassed Majuba’s three silos had since been installed, which enabled Eskom to ramp-up output to 1 200 MW on Monday.

The short-term solution required additional front-end loaders to shovel coal at the stockyard onto trucks that would deliver coal to conveyors that feed the units’ coal bunkers. An initial rate of 15 loads an hour was envisaged at a single feeder point, which was likely to be doubled at a later stage.

Nevertheless, the utility warned that the system would be under “extreme pressure on Wednesday and Thursday as the water reserves that we built up over the weekend for our peaking plants will be depleted”.

The utility said additional units had also been returned from maintenance and that customers experiencing outages should contact their direct electricity providers, as it could be a localised problem.

The capacity available to meet the Monday evening peak demand was 31 800 MW, while demand was forecast to be 31 317 MW. Planned maintenance was reported to be 3 200 MW, while unplanned outages had surged to 8 200 MW.

Capacity available to meet Tuesday's evening peak demand was estimated at 32 321 MW, while demand was forecast at 30 990 MW.

On Monday afternoon, Eskom was still expecting to have sufficient supply to meet the Wednesday and Thursday peaks.

Group executive for sustainability Steve Lennon indicated on Sunday that load would be shed should it be necessary to protect the power system from total collapse. He said that Eskom was acutely aware of the economic and social costs of load shedding and would, therefore, only “take as much as we need and as little as possible”.

It would also continue to draw on its expensive diesel-fuelled open cycle gas turbines in the Western Cape, as the economic cost of load shedding was “ten times” that of the cost of producing power at the facilities.

Eskom was currently viewing the Majuba silo collapse as an “isolated incident”, stating that a conveyor maintenance crew detected the first sign of structural weakness less than an hour ahead of the collapse.

The crew, which was evacuated, detected coal falling from a crack about 30 m up on the wall of the 40 m silo's concrete structure. The crack was detected at 12:30 on Silo 20 and the collapse, which was recorded by cameras on site, took place at 13:12.

An investigation was under way into the cause of the failure, but Eskom indicated that there were signs that the reinforcing-steel bar had corroded. The silo was built in 1994, was independently inspected in September 2013 and was meant to have a design life of 50 years.

ESKOM KNEW

However, trade union Solidarity argued on Monday that Eskom had been aware of structural problems with the silo for months and accused the company of negligence.

Solidarity said in a statement that Eskom workers had been monitoring resonances at the silo since January and that, by June, and again three weeks prior to the collapse, it had been found that the silo’s vibration had worsened.

“Vibration of a concrete structure is extremely problematic. The vibration caused or worsened weaknesses in the silo and as the vibration increased, it eventually led to the collapse,” Solidarity’s head of the energy industry Deon Reyneke said.

Reyneke also warned that the temporary measures being implemented could jeopardise safety at the power station.

“Through its negligence, Eskom is placing its employees at risk. To fully supply all six units at the power station, hundreds of trucks per hour have to offload coal at temporary conveyors close to the furnaces. Apart from the risk of truck accidents and higher operating costs, it also holds a fire hazard."