To build a pumped storage scheme you need a specific combination of factors to be just right, they are: the right geology, enough available water, two sites to build dams – close enough together, but with at least 400 meters difference in altitude, it needs to be close to the National Grid and close to existing infrastructure. Eskom started looking for such sites in the 1980's. Initially more than 90 potential sites were investigated, resulting in the short-listing of only three. The best site was selected north-east of Van Reenen's Pass, spanning the escarpment of the Little Drakensberg, and straddling the provincial boundary of the Free State and KwaZulu-Natal.
Initially more than 90 potential sites were investigated, culminating in the short-listing of only three. The final selection was a site north-east of Van Reenen's Pass, spanning the escarpment of the Little Drakensberg, and straddling the provincial boundary of the Free State and KwaZulu-Natal.
This is also the continental watershed between the Vaal River catchment, flowing into the Atlantic Ocean, and the Tugela River catchment, flowing into the Indian Ocean.
History behind the name Ingula
Initially known as ‘Braamhoek’, the name was officially changed to ‘Ingula’ in March 2007. The name ‘Ingula’ alludes to the creamy contents at the top of a milk calabash. The quest to find an appropriate name for Ingula Power Station was inspired by the mountains and foamy river-waters, and the rich cultural symbols and traditions of the indigenous people on both sides of the border.
The pumped storage scheme consists of an upper and a lower dam, each capable of holding approximately 22 million cubic metres of water. The dams, 4.6km apart, are connected by underground waterways passing through a subterranean powerhouse with four 333 MW generators.
To generate electricity during times of peak demand, water is released from the upper dam, passing through the pump/turbines, into the lower dam.
During times of low energy demand, the pump/turbines are used to pump the water from the lower dam, back to the upper dam.