By Chris van Gass

A planned second R4,5billion open-cycle gas turbine generating station like the one being built for Eskom at Atlantis, in Western Cape, would go a long way towards boosting its reserve capacity to handle SA's peak electricity demand, the power utility said on Tuesday.

And Eskom's board will decide next month whether to build a second conventional nuclear power station.

Brian Dames, MD of Eskom Enterprises, said on Tuesday the second plant at Atlantis would boost capacity by 600MW to more than 1000MW.

Together with a smaller plant at Mossel Bay, the Atlantis plant is part of Eskom's long-term plan to lift the percentage of its reserve capacity, which now stands at about 10% of total capacity, up to 15%.

The plant has been included in Eskom's R97billion capital expenditure drive for the next five years.

Dames said the addition of reserve capacity would be Eskom's "insurance" to enable it to meet peak electricity demand, which last winter saw extensive power outages in Western Cape, and to strengthen the electricity network of the province.

But this electricity will cost much more than that of other power stations, with Atlantis burning 160 tons of fuel at 5% of load factor.

Eskom is still the world's lowest-cost electricity producer with its existing power stations, mainly coal- fired, producing at an average 17c/kW and newer plants at 25c-30c/kW.

The Atlantis plant will produce electricity at R1,50/kW. Building the first 600MW gas turbine plant at Atlantis, scheduled for completion in July, along with a smaller 450MW plant at Mossel Bay, has been fast-tracked for completion.

The plant at Atlantis will be fired by diesel. The Mossel Bay plant, on the PetroSA site, will be fired by paraffin supplied by PetroSA.

Both plants will feed electricity into the national grid through additional lines linking the power stations to existing lines.

The technology used in the open-cycle turbines means that the power stations could be converted into combined-cycle gas plants, using natural gas, should enough natural gas be available from "promising" west coast exploratory sites.

Dames said that, depending on the price structure of natural gas on world markets, such conversions could be implemented to offset the high cost of diesel and paraffin.

He said the Atlantis and Mossel Bay plants were "on schedule" for completion in July.

Eskom will also consider the latest available technology from potential suppliers, and over 12 months move closer to finalising the site of the possible second nuclear plant.

Dames said Eskom managed about five such sites, stretching from Northern Cape's west coast to Nelson Mandela Bay.

Business Day