Kárahnjúkar Dam









Kárahnjúkar Hydropower Plant (Kárahnjúkavirkjun), officially called Fljótsdalur Power Station (Fljótsdalsstöð) is a hydroelectric power plant in Fljótsdalshérað municipality in eastern Iceland, designed to produce 4,600 gigawatt-hours (17,000 TJ) annually for Alcoa's Fjarðaál aluminum smelter 75 kilometres (47 mi) to the east in Reyðarfjörður. With the installed capacity of 690 megawatts (930,000 hp), the plant is the largest power plant in Iceland.

Kárahnjúkar Dam
The project, named after the nearby Kárahnjúkar mountains, involves damming the rivers Jökulsá á Dal and Jökulsá í Fljótsdal with five dams, creating three reservoirs. Water from the reservoirs is diverted through 73 kilometres (45 mi) of underground water tunnels and down a 420-metre (1,380 ft) vertical penstock towards a single underground power station. The smelter became fully operational in 2008 and the hydropower project was completed in 2009.

The Kárahnjúkar Dam (Kárahnjúkastífla) is the centrepiece of the five dams and the largest of its type in Europe, standing 193 metres (633 ft) tall with a length of 730 metres (2,400 ft) and comprising 8.5 million cubic metres (300×106 cu ft) of material.

The project has been heavily criticised for its environmental impact and its use of foreign workers.

The hydroelectricity project harnesses the rivers Jökulsá á Dal and Jökulsá í Fljótsdal by creating three reservoirs with five concrete-face rock-filled embankment dams; three on the Jökulsá á Dal and two on the Jökulsá í Fljótsdal. After being used in the Fljótsdalur Power Station, all water used in electricity production is discharged into the river Jökulsá í Fljótsdal.

Three dams on the Jökulsá á Dal; the Kárahnjúkar Dam (Icelandic: Kárahnjúkastífla), the Desjará Dam (Icelandic: Desjarárstífla) and the Sauðárdalur Dam (Sauðárdalsstífla) create the Hálslón Reservoir. At 193 metres (633 ft) tall and 730 metres (2,400 ft) long, the Kárahnjúkar Dam is the largest dam in the project and the largest of its type in Europe as well. The 60-metre (200 ft) tall and 1,000-metre (3,300 ft) long Desjará Dam and the 25-metre (82 ft) tall and 1,100-metre (3,600 ft) long Sauðárdalur Dam are saddle or auxiliary dams that maintain the desired height of the Hálslón Reservoir.

Water from the 25-kilometre (16 mi) long, 2.1-cubic-kilometre (1,700,000 acre⋅ft) capacity Hálslón Reservoir (about the size of Manhattan island in New York) is diverted down a 39.7-kilometre (24.7 mi) long, 7.2–7.6-metre (24–25 ft) diameter headrace tunnel towards the Fljótsdalur Power Station. More details