Kariba South Power Station
Kariba South Power Station is a hydro-power station owned and operated by the Zimbabwe Power Company.
Background
In 1955, it was decided to dam the Zambezi River at the Kariba Gorge to supply power to Zimbabwe and Zambia. Three years later and despite many difficulties, including record-breaking floods, the Zambezi River was dammed and Lake Kariba began to form.
In 1956, engineers started to mine a vast cavern that would house a power station, about 174 metres below the ground and by 1959, the first generator was commissioned. All 6 generators were in operation by 1962, with a generation capacity of 666MW. The station has since been uprated to 125MW per unit making the total installed capacity 750MW.Currently the output from the station is slightly lower than 750MW because of the opening of the flood gates which tend to lower the head.
Electricity is generated by drawing water from Lake Kariba through a short horizontal intake via a radial gate and through a vertical penstock to the turbine spiral casing. After passing through the turbine and producing power in the coupled generator, water at reduced pressure is passed through a suction cone and draft tube to the tailrace. This is discharged downstream of the dam, back into the Zambezi River.
The Zambezi River Authority (ZRA), a statutory body formed by the Zimbabwean and Zambian governments, is responsible for the allocation of water used by Zimbabwe’s Kariba South and Zambia’s Kariba North Power Stations.
Kariba South Power Station is used for frequency, tie line and automatic generation control and the station’s operational efficiency is above 90 percent. Depending on inflows into the lake, the station can generate a maximum of 5000 GW/hrs with a load factor of 80 percent.
