| Onekaka Hydro Power Station | |
| Image Alt: | View inside a power station |
| Country: | New Zealand |
| Location: | Onekaka |
| Dam Type: | Concrete arch |
| Dam Height: | 10m (30feet) |
| Plant Operator: | Onekaka Energy Ltd |
| Plant Hydraulic Head: | 200m (700feet) |
| Plant Turbines: | Two |
Onekaka Power Station is a small hydro-electric generating station on the Onekaka River, in Golden Bay / Mohua, New Zealand. The first power station on the river was built in 1928–29 to provide power for the Onekaka Ironworks. The original scheme included a concrete arch dam 10m (30feet) high, a penstock 1.25km (00.78miles) long, and a powerhouse containing a Boving pelton wheel, rated at 250kW.
After the Onekaka Ironworks closed, the power station remained in operation from 1937 to 1944, generating electricity for the Golden Bay area.[1] The scheme was abandoned in the 1950s. A group of local hydro enthusiasts began work on a rebuild in 1995, and formed a company Onekaka Energy Ltd to manage the re-development and operation of the scheme.[2] Up to a second would be diverted from the Onekaka River,[3] and opponents expressed concerns that a reduction in minimum flows in the river would affect the native fish, the shortjaw kōkopu.[4]
The new scheme uses the historic concrete arch dam, but a new penstock was built on the same alignment as the original. The new penstock extends a further 200abbr=onNaNabbr=on, to a new powerhouse downstream from the original site. New generating equipment for the scheme was obtained from salvage of two 500kW auxiliary hydro-generator sets that had originally been used at the Tuai Power Station, a 60MW station built as part of the Lake Waikaremoana scheme in the 1920s. The hydraulic head of the station is 200m (700feet)[5] and the rated capacity of the new generating plant is 940kW.[6] It was commissioned in November 2003,[7] and produces 3.5 GWh annually. The output is sold on the New Zealand electricity market. The scheme produces 10 to 20 percent of the electricity used in Golden Bay.[8]
One unusual feature of this power station is that it is remotely monitored and controlled using text messages via the cellular phone network.