| Steenbras Power Station | |
|---|---|
 Steenbras Upper Dam (l) and the lower reservoir (r) | |
  Steenbras Power Station Map of South Africa showing the location of Steenbras Power Station Show map of Cape Town Steenbras Power Station Steenbras Power Station (Western Cape) Show map of Western Cape Steenbras Power Station Steenbras Power Station (South Africa) Show map of South Africa | |
| Country | South Africa |
| Location | City of Cape Town,Western Cape |
| Coordinates | 34°09′08″S18°53′43″E / 34.15222°S 18.89528°E /-34.15222; 18.89528 |
| Purpose | Power |
| Status | Operational |
| Opening date | 1979 |
| Owner | City of Cape Town |
| Operator | City of Cape Town |
| Dam and spillways | |
| Impounds | Steenbras River |
| Hydraulic head | 275 metres (902 ft) |
| Turbines | 4 x 45 MW |
| Installed capacity | 180 megawatts (240,000 hp) |
| Annual generation | ~250 GWh |
TheSteenbras Power Station, alsoSteenbras Hydro Pump Station, is a 180MWpumped-storage hydroelectric power station commissioned in 1979 inSouth Africa. The power station sits between theSteenbras Upper Dam and a small lower reservoir on the mountainside below.[1] It acts as an energy storage system, by storing water in the upper reservoir during off-peak hours and releasing that water to generate electricity during peak hours. TheCity of Cape Town uses the power station forload balancing and to mitigate againstloadshedding caused by theSouth African energy crisis.[2] This power station is reported to be the firstpumped-storage hydroelectric power station to be built on theAfrican continent.[3]
TheSteenbras Upper Dam impounds the Steenbras River at an altitude of approximately 375 metres in theHottentots Holland Mountains, upstream of the originalSteenbras Dam (which is not part of the hydroelectric scheme). The Steenbras Power Station and the scheme's lower reservoir are situated on the lower slopes of the mountain at an altitude of approximately 100 metres, close to the town ofGordon's Bay and 50 kilometres (30 mi) to the south-east of central Cape Town. A series of tunnels connects the upper reservoir to the power station.
The power station is operated by the Electricity Department of theCity of Cape Town.[4] It consists of four hydroelectric turbines, each rated at 45 MW, for a total capacity of 180 MW. During peak hours, water from the upper reservoir is used to turn the turbines to generate clean energy.[3] During off-peak hours (from 11pm until 7am), the same hardware, this time functioning as electric pumps, uses electricity purchased from the national grid to pump water from the lower reservoir back into the upper reservoir. The process is repeated, as the need arises and as hydrodynamic capacity allows.[3]
The output of the power station is generally constrained by the 3,560 megalitres (126×10^6 cu ft) capacity of the lower reservoir. At maximum output the station can run for about twelve hours before the lower reservoir is full; in practice it is typically run for four to five hours a day. In winter, which is the rainy season in that part of South Africa, if the upper reservoir is sufficiently full, water can be released from the lower reservoir to the Faure water treatment works instead of being pumped back up.[1]