REUTERS

Electricity pylons carry power from Cape Town's Koeberg nuclear power plant July 17, 2009.

Eskom said on Friday in its twice-weekly capacity update service that unplanned outages were 5,639 Megawatt (MW) on February 3 from 5,411 MW on January 30, 5,521 MW on January 26, 5,497 Megawatt (MW) on January 23, 5,373 MW on Jan 19, 4,274 MW on Jan 16 and 3,678 MW on January 13.

The electricity generating capacity available to meet this evening's peak demand is 32,513 MW, while demand is forecast at 30,715 MW. Current planned maintenance stands at 4,845 MW.

Peak demand for the coming week is forecast at: 29,385 MW on Saturday, 29,104 MW on Sunday, 31,337 MW on Monday, 31,376 MW on Tuesday, 31,454 MW on Wednesday, and 31,265 MW on Thursday.

Eskom continues to make progress with its programme of planned maintenance but the system remains tight.

Eskom has moved to twice a week updates instead of the previous quarterly updates in line with its commitment to regular and transparent communication on the power system, which is expected to be constrained for at least the next two years.

On January 17 peak demand of 31,278 MW met by available capacity of 32,954 MW. That is a margin of 1,676 MW (5%) or around three modern 600 MW coal-fired generators.

On January 9 peak demand of 30,282 MW was met by available capacity of 30,742 MW or a margin of only 460 MW (less than one generating unit at a modern coal generating plant) or only 1.5%. The internationally accepted safe margin is 15%.

The reason for this low margin in SA is that Eskom carries out planned maintenance on its power stations during the seasonally low demand summer months, so that the power stations are ready to handle the peak winter demand months of June and July, when service delivery protests also peak.

On January 12, capacity taken offline for planned maintenance was 4,461 MW or around nine generating units, but unplanned outages were 3,678 MW or around seven generating units. Last year in February, a 600 MW generating unit at Duvha failed during tests as it was being returned to service, while in January 2003 a similar event took place.

This year and next year Eskom does not have the spare capacity to be able to have a large generating unit fail, as the first unit of the new Medupi power station will only come on line in 2013. - I-Net Bridge