Manapouri Power Station

Manapouri Power Station
The Manapouri Power Station machine hall
Location of Manapouri Power Station in New Zealand
Country	New Zealand
Location	west end of Lake Manapouri, Fiordland National Park, Southland
Coordinates	45°31′17″S 167°16′40″E / 45.52139°S 167.27778°E / -45.52139; 167.27778Coordinates: 45°31′17″S 167°16′40″E / 45.52139°S 167.27778°E / -45.52139; 167.27778
Status	Operational
Construction began	February 1964
Opening date	September 1971
Construction cost	NZ$135.5 million (original station) NZ$200 million (second tailrace tunnel) NZ$100 million (half-life refurbishment)
Owner(s)	Meridian Energy
Reservoir
Creates	Lake Manapouri
Catchment area	3,302 km2 (1,275 sq mi)
Surface area	141.6 km2 (54.7 sq mi)
Maximum water depth	444 m (1,457 ft)
Power station
Type	Conventional
Turbines	7× vertical Francis
Power generation
Nameplate capacity	850 MW
Capacity factor	68.4% / 79.7%
Annual output	5100 GWh
Lake Manapouri is a natural lake - the drop between it and the sea is used by Manapouri station. ^c The former figure is based on the installed capacity of 850 MW, while the latter figure is based on the resource consent limited capacity of 800 MW

Manapouri Power Station is an underground hydroelectric power station on the western arm of Lake Manapouri in Fiordland National Park, in the South Island of New Zealand. At 850 MW installed capacity (although limited to 800 MW due to resource consent limits), it is the largest hydroelectric power station in New Zealand, and the second largest power station in New Zealand. The station is noted for the controversy and environmental protests by the Save Manapouri Campaign against the raising the level of Lake Manapouri to increase the station's head, which galvanised New Zealanders and were one of the foundations of the New Zealand environmental movement.

Completed in 1971, Manapouri was built to supply electricity to the Tiwai Point aluminium smelter near Bluff, some 160 km (99 mi) to the southeast. Later, it was also connected into the South Island transmission network. The station utilises the 230-metre (750 ft) drop between the western arm of Lake Manapouri and the Deep Cove branch of the Doubtful Sound 10 km (6.2 mi) away to generate electricity. The construction of the station required the excavation of almost 1.4 million tonnes of hard rock to build the machine hall and a 10 km tailrace tunnel, with a second parallel tailrace tunnel completed in 2002 to increase the station's capacity.

Since April 1999, the power station has been owned and operated by state-owned electricity generator Meridian Energy.

The power station machine hall was excavated from solid granite rock 200 metres below the level of Lake Manapouri. Two tailrace tunnels take the water that passes through the power station to Deep Cove, a branch of Doubtful Sound, 10 kilometres (6.2 mi) away. Access to the power station is via a two-kilometre vehicle-access tunnel which spirals down from the surface, or a lift that drops 193 metres (633 ft) down from the control room above the lake. There is no road access into the site; a regular boat service ferries power station workers and tourists 35 km across the lake from Pearl Harbour, located in the town of Manapouri at the southeast corner of the lake.