Public Enterprises Minister Malusi Gigaba urges South Africans to use electricity sparingly this winter to avoid further strain on an already constrained power system.

“The provision of adequate and reliable electricity remains an essential element to supporting economic growth in the country’s developmental objectives. I would like to urge the country to continue supporting us in the efforts to keep the lights on, especially during this time of constrained power supply. I appeal to you to pay attention to the power saving adverts on your television and to keep supporting the initiative by State-owned power utility Eskom to provide reliable and stable power,” said Gigaba at the State of the System briefing in Johannesburg on April 22.

The deterioration in the performance of power stations since last year’s September rains led to significant challenges for Eskom in supplying power to the country.

“Some of the [other] key contributing factors to the strain on the system included the reduction of capacity imported from Cahora Bassa from about 1 500 MW to 650 MW, owing to technical failure at the Songo substation, in Mozambique, and the subsequent failure of that transmission line, owing to floods in early 2013; secondly, the unplanned outage of one of the Koeberg units, in the Western Cape, which put added strain on the coal-fired power stations; and, thirdly, the prevailing poor coal quality, resulting in significant load losses at some of the power stations,” he added.

While some additional power is expected to come back onto the grid from the restoration of power from Koeberg Unit 1 and Cahora Bassa, the 2 000 MW of planned maintenance will offset this over winter. According to Eskom, peak demand in winter can be up to 3 000 MW higher – the equivalent of up to five units of a large power station.

Koeberg being the only nuclear power station in Africa, it boasts the largest turbine generators in the southern hemisphere. It consists of two 900 MW units, with an installed capacity of 1 800 MW, and its average energy production over the last three years is 13 668 GWh, states Eskom.

The utility shifted some scheduled maintenance work, while some plants experienced unplanned outages where power station units tripped or produced below the expected capac- ity estimates.

“Until the Medupi power station, in Lim- popo, and the Kusile power station, in Mpumalanga, come on line, efforts must continue to ensure that operational perfor- mance at Eskom power stations improves, power plants are well maintained, the necessary procedures are put in place to ensure that the electricity demand is met and that the power system’s integrity is constantly maintained,” explained Gigaba.

Eskom has, to date, been able to ensure that there are no blackouts, despite the challenges experienced.

Gigaba also stated that the improvement of Eskom’s maintenance practices was a step in the right direction and would go a long way towards ensuring the reduction of the maintenance backlog. The backlog has been reduced from 36 units requiring maintenance in January 2012 to 23, as of the end of March.

Until the backlog is dealt with and main-tenance is sustained at appropriate levels, the performance of power stations will remain a challenge.

Also, Eskom CEO Brian Dames said at the briefing Cahora Bassa was expected to have increased its output to 1 300 MW by the end of April this year, with the final 200 MW expected to be restored by the third quarter of 2013.

“To ensure that the progress made to date is sustained, the Department of Energy will continue to monitor Eskom’s progress in implementing measures to ensure a reliable weekly electricity supply on a permanent basis,” Dames noted.