Tokaanu Power Station

Tongariro Hydro Scheme (Tokaanu, Rangipo)
Country	New Zealand
Location	Central North Island
Commission date	1973 (Tokaanu) 1983 (Rangipo) 2008 (Mangaio)
Owner(s)	Genesis Energy
Power generation
Units operational	Four (Tokaanu) Two (Rangipo) One (Mangaio)
Nameplate capacity	240 MW (Tokaanu) 120 MW (Rangipo) 2 MW (Mangaio)
Annual output	1350 GWh (Total)

The Tongariro Power Scheme is a 360 MW hydroelectricity scheme in the central North Island of New Zealand. The scheme is currently operated by electricity generation company Genesis Energy.

The scheme takes water from tributaries of the Rangitikei, Whangaehu, Whanganui, and Tongariro rivers, which drain a 2,600-square-kilometre (1,000 sq mi) area covering Ruapehu, Ngauruhoe, Tongariro and the western Kaimanawa Ranges. The water is then sent through a large canal and tunnel system to generate electricity at three hydro power stations, located at Rangipo (120 MW), Tokaanu (240 MW) and Mangaio (2MW). The water is then drained into Lake Taupo where it is stored for further use in the succession of Waikato River power stations.

The scheme generates approximately 1350 GWh of electricity annually, and contributes 4 percent of New Zealand's electricity generation.

The Eastern Diversion starts at the Waiharakeke Stream, a tributary to the Whangaehu River, where the diversion starts. Water from here and 22 other intakes, including from the Waihianoa and Makahikato Streams, passes into the 8.4-kilometre (5.2 mi) long underground Wahianoa Aqueduct. The aqueduct heads eastward, passing under the actual Whangaehu River, but not taking any water from it due to the fact it drains Mount Ruapehu's crater lake and is too acidic. At the end of the aqueduct, near the Desert Road (State Highway 1), water is then diverted through the 1.4-kilometre (0.87 mi) Mangaio Tunnel under the State Highway and either into Mangaio Power Station or a drop structure to enter Lake Moawhango via the Mangaio Stream.

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Wikipedia