Cruachan Power Station Turbine Hall

The Cruachan Power Station (also known as the Cruachan Dam) is a pumped-storage hydroelectric power station in Argyll and Bute, Scotland. The scheme can provide 440 MW of power and produces 7.1 GWh/year.
The turbine hall is located inside Ben Cruachan, and the scheme takes water between Cruachan Reservoir to Loch Awe, a height difference of 396 metres (1,299 ft). It is one of only four pumped storage power stations in the UK, and is capable of providing a black start capability to the National Grid.
Construction began in 1959 to coincide with the Hunterston A nuclear power station in Ayrshire. Cruachan uses cheap off-peak electricity generated at night to pump water to the higher reservoir, which can then be released during the day to provide power as necessary. The power station is open to visitors, and around 50,000 tourists visit it each year
The power station is on the A85 road, about 8 km or 5 miles west of Dalmally, on a branch of Loch Awe leading to the River Awe, which is the outflow from the loch, at its NW corner. There is a seasonally open Falls of Cruachan railway station nearby.
Construction commenced in 1959, and the power station was opened by Queen Elizabeth II on 15 October 1965.

There are four Francis turbines, which operate as both pumps and generators. These are housed in a cavern within Ben Cruachan, which is 91.5 metres (300 ft) long, 23.5 metres (77 ft) wide and 38 metres (125 ft) high, with an adjacent transformer hall. The chamber is at a depth of around 300 metres (980 ft), and is located within a hard granite intrusion. Construction of the power station required the removal of 220,000 cubic metres (7,800,000 cu ft) of rock.[20] Access to the hall is gained by a road tunnel 1 kilometre (0.62 mi) long, 4 metres (13 ft) high and 7 metres (23 ft) wide, which is warm and humid enough to allow tropical plants to grow.[