Although public participation meetings were held on September 14 and 15 to discuss the Tubatse pumped storage scheme, Eskom said yesterday at the weekly implementation of the energy action plan briefing that the Tubatse pumped storage scheme was still in the development phase, so questions posed by Business Report could not be answered.
To cope with the morning and evening peak demands, Eskom uses pumped storage schemes such as Ingula and expensive-to-run diesel-fueled Open Cycle Gas Turbines (OCGT).
Pumped storage uses off-peak power to pump water to an upper dam and then releases this water to a lower dam to generate power during peak periods.
OCGT use diesel to power turbines, but this is more than 20 times more expensive than coal-fired power.
The commitment to “keep the lights on” meant that instead of using OCGT only during peak periods, Eskom was using it during daylight periods. The result was that generating costs escalated sharply, which Eskom tried to recoup by asking for higher tariff increases.
Eskom said investigation for the new pumped storage scheme began in 1985 when planners identified 90 potential sites across the country.
By 2002 they had narrowed down the choice to just three sites and construction at Ingula began in 2006.
The 2008 financial crisis meant that the Tubatse pumped storage scheme had to be put on hold. Former Eskom Chief Operating Officer Jan Oberholzer told Business Report in May 2022 that Tubatse was once again on the project list with a 10-year timeline.
The documents released ahead of the public participation meetings now show that construction is expected to commence in November 2027 and is due to be completed in October 2033.
That would be faster than Eskom took to complete the Ingula pumped storage scheme, where construction started in 2006, but the final unit only entered into commercial operation in July 2016.
If Tubatse had similar project delays, this would mean it would only be finished in 2037, rather than 2033.
In the case of Ingula, the only operational cost is the efficiency loss of electricity as the whole operational staff is only five people in a simple control room.
This efficiency loss is only 20% as it takes 20 hours to fill the upper dam, which can provide 16 hours of power when the water is released to run the four generators each weighing 230 tons and rotating at 330 km/hour.
The water that is released would fill eight Olympic-sized swimming pools every minute. Tubatse would be very similar in design to Ingula.
The main cost of Ingula and Tubatse is the capital cost as two dams have to be constructed, the tunnels and power house have to be excavated, the turbine/pumps have to be installed and the high-voltage transmission lines have to be linked to the rest of the national grid.
The total cost for Ingula was some R27 billion.
Business Report asked how much Tubatse would cost and how it would be financed, but as the project is in the development phase, these questions could not be answered.
The likely cost would be near R50 billion, and could be financed as a Special Purpose Vehicle using so-called “green bonds”.
Helmo Preuss is an Economist at Forecaster Ecosa.