The first unit – unit 4 – of the Ingula pumped-storage power station on the escarpment of the Little Drakensberg mountain range straddling the border of KwaZulu-Natal and the Free State has come into commercial operation, Eskom said on Sunday.

Eskom’s group capital division handed over the unit to its generation division for commercial operation at 6pm on Friday, the parastatal said in a statement.

“This means an additional 333 MW being added to the grid and thereby ensuring further security of supply.

“Commercial operation is when the construction and optimisation of the unit is complete and the operator, Eskom’s generation division in this case, takes over the plant and runs it on a commercial basis, ie supplying power into the national grid. It is the first of four units to commercially support the national grid ahead of schedule, powering South Africa into the future,” Eskom said.

Unit 4 was synchronised to the national grid on March 25 and had been undergoing optimisation while supporting the national grid. Construction at Ingula started in 2006. All four of Ingula’s units were scheduled for commercial operation in 2017.

“Ingula’s four units are located 350 metres underground in the world’s largest machine hall in mud-rock. To turn the more than 500 ton rotating mass of the generator rotor and turbine water is released from Ingula’s upper dam, Bedford Dam, situated 460 metres higher and 2km away.

“Water flows at high speed down to the turbines at around 60km/h with enough water passing through each turbine to fill an Olympic-sized swimming pool in six seconds. Rotating at 428 revolutions per minute each unit will produce 333 MW, a total for the station of 1 332 MW.

“On completion of all four units Ingula will be part of Eskom’s peaking fleet of power stations. It can respond to demand increases on the national grid within two-and-a-half minutes. Upon completion Ingula will be Africa’s newest and largest pumped storage scheme and the nineteenth largest in the world.”

Ingula unit 3 was currently under repair after an “incident” was experienced during the optimisation process, post synchronisation. This unit was synchronised to the national grid on March 6 and supported the grid until April 6 when the incident occurred.

Ingula unit 2 was synchronised to the national grid on May 22 and was under optimisation. Ingula unit 1 was still under construction. Ingula units 3, 2, and 1 were on track for commercial operation in 2017, Eskom said.