Kárahnjúkar Hydropower Plant

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Kárahnjúkastífla Dam
Kárahnjúkar Hydropower Plant
Kárahnjúkastífla Dam, looking south.
Kárahnjúkar Hydropower Plant is located in Iceland
Kárahnjúkar Hydropower Plant
Location of Kárahnjúkastífla Dam
Kárahnjúkar Hydropower Plant in Iceland
Country Iceland
Coordinates 64°56′N 15°48′W / 64.933°N 15.800°W / 64.933; -15.800Coordinates: 64°56′N 15°48′W / 64.933°N 15.800°W / 64.933; -15.800
Status Operational
Opening date 2009
Dam and spillways
Type of dam Embankment, concrete-face rock-fill dams
Impounds Jökulsá á Dal River
Jökulsá í Fljótsdal River
Height 193 m (633 ft)
Length 730 m (2,400 ft)
Dam volume 8.5×10^6 m3 (300×10^6 cu ft)
Spillways 1
Spillway type Tunnel
Creates Hálslón Reservoir
Total capacity 2.1 km3 (1,700,000 acre·ft)
Maximum length 25 km (16 mi)
Operator(s) Landsvirkjun
Turbines 6 x 115 MW (154,000 hp) Francis-type
Installed capacity 690 MW
Annual generation 4,600 GWh

Kárahnjúkar Hydropower Plant (Icelandic Kárahnjúkavirkjun) 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 Fjardaál 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 hydroelectric power plant in Iceland. The project, named after nearby Mount Kárahnjúkur, involves damming the Jökulsá á Dal river and the Jökulsá í Fljótsdal river with five dams, creating three reservoirs. Water from the reservoirs is then 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 hydro-power project was completed in 2009.[1]

The Kárahnjúkastífla Dam is the centerpiece 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 (300×10^6 cu ft) of material.

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


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

Kárahnjúkastífla Dam

Three dams on the Jökulsá á Dal River; the Kárahnjúkastífla Dam, the Desjarárstífla Dam and the Sauðárdalsstífla Dam create the Hálslón Reservoir. At 193 metres (633 ft) tall and 730 metres (2,400 ft) long, the Kárahnjúkastífla 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 Desjarárstífla Dam and the 25-metre (82 ft) tall and 1,100-metre (3,600 ft) long Sauðárdalsstífla 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.[2][3]

On the Jökulsá í Fljótsdal River, the 26-metre (85 ft) tall and 1,650-metre (5,410 ft) long Kelduárstífla dam forms the 60-million-cubic-metre (2.1×10^9 cu ft) capacity Kelduárlón reservoir. Downstream from the Kelduárstífla dam is the 37-metre (121 ft) tall, 620-metre (2,030 ft) long Ufsarstífla dam which forms the Ufsarlón pond, a much smaller reservoir. Water from the Ufsarlón pond is diverted down a 13.3-kilometre (8.3 mi) long, 6-metre (20 ft) diameter headrace tunnel where it joins the Hálslón reservoir headrace tunnel.[2][3]

Before each of the headrace tunnels from the Hálslón reservoir or Ufsarlón pond reach the underground power station, they both join to form a single combined headrace tunnel. The single headrace tunnel later splits into two 0.8-kilometre (0.50 mi) long, 4-metre (13 ft) diameter steel-lined penstocks (tunnels) and the water makes a rapid descent down a final 420-metre (1,380 ft) vertical penstock into the power station. The underground Fljótsdalur Power Station contains six vertical-axis Francis turbine generators rated at 115 MW each. The power station has a combined capacity of 690 MW and discharge of 144 cubic metres per second (5,100 cu ft/s) (averages 110 cubic metres per second (3,900 cu ft/s)) into the Jökulsá í Fljótsdal River via tailrace tunnels and canals. The power production corresponds to a capacity factor of 76%,[clarification needed] which is relatively high for a hydroelectric facility. Power produced is then transmitted to Alcoa's Fjardaál aluminium smelter 75 kilometres (47 mi) to the east in Reyðarfjörður.[2][3]

Fjardaál aluminium smelter[edit]

The Fjardaál aluminium smelter was completed June 2007 and reached full operation in April 2008. Construction began in 2004 and the facility contains a smelter, cast house, rod production and deep-water port. The smelter employs 450 people and produces 940 tons of aluminium a day, with capacity of 346,000 metric tons of aluminium per year. Fjardaál means "Aluminium of the Fjords" in Icelandic.[3][4]


Using the Jökulsá á Dal and Jökulsá í Fljótsdal Rivers along with other resources in eastern Iceland has been on the drawing board since the 1970s. From 1975-2002, several international companies had planned or attempted to build a metal plant at Reyðarfjörður that would be powered by a hydroelectricity project similar to the Kárahnjúkar. All failed because of opposition to the project until Alcoa along with the Government of Iceland and Landsvirkjun, Iceland's national power company committed to the massive project in 2002.[5]


Construction of Kárahnjúkastífla Dam, concrete-face backside
The end of the tunnel at Skriðuklaustur leading water from Kárahnjúkastífla Dam to the power plant.

The project is funded by Landsvirkjun, which operates the dams and Fljótsdalur Power Station. The Italian company Impregilo is the largest contractor working on the dams.[6] The total cost of the hydropower project is 1.3 billion USD. The penstock was built in place by the German company DSD-NOELL (Würzburg) whereas ATB Riva Calzoni of Italy provided intake structures, wheels gates and sliding gates. In total, more than 4,000 tons of steel were used for the steel liner.

Preparatory work on the project began in August 2002 and construction on the Kárahnjúkastífla Dam and headrace tunnels for the Hálslón reservoir began in April 2003. In September of the same year, construction began on the underground power station. Construction on both the Desjarárstífla Dam and the Sauðárdalsstífla Dam began in April 2004. In June 2006, construction of the Kelduárstífla Dam and Ufsarstífla Dam began and in September, the Hálslón Reservoir began to fill. In mid-2008, the Kelduárstífla and Ufsarstífla Dams were complete and the Ufsarlón pond headrace tunnel was ready.[3][7]

Construction on the headrace tunnels was done by three full-face tunnel boring machines, while remaining areas were drilled and blasted.[3] This was the first time that tunnel boring machines were used in Iceland.[8]

The project was documented in a MegaStructures program of the National Geographic Channel, and the Discovery Channel's Extreme Engineering, along with mention in the Sigur Rós 2006 documentary Heima (At Home), where the band played at a protest against the building of the dam.


The dams have been the frequent subject of protests by environmentalists for many reasons. The area is within the second largest (formerly) unspoiled wilderness in Europe and covers about 1,000 square kilometres (390 sq mi) in total and the rivers that supply water to the project are part of Europe's largest glacier, the Vatnajökull. The project as a whole has also been criticised heavily in the book Draumalandið and subsequent 2009 documentary Dreamland. About 70% of the workforce was composed of foreign workers.[9]

See also[edit]


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