Kárahnjúkar Hydropower Plant ( ), officially called Fljótsdalur Power Station
( )
is a
hydroelectric
Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...
power plant in
Fljótsdalshérað municipality in eastern
Iceland
Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...
, designed to produce annually for
Alcoa
Alcoa Corporation (an acronym for "Aluminum Company of America") is an American industrial corporation. It is the world's eighth-largest producer of aluminum. Alcoa conducts operations in 10 countries. Alcoa is a major producer of primary alu ...
's Fjarðaál
aluminum smelter to the east in
Reyðarfjörður
Reyðarfjörður () is a town in Iceland. It has a population of 1,368 (2024) and is one of the most populated villages that constitute the municipality of Fjarðabyggð.
History
The town is at the bottom of the eponymous fjord
In physical g ...
. With the installed capacity of , the plant is the
largest power plant in Iceland. The project, named after the nearby Kárahnjúkar mountains, involves damming the rivers
Jökulsá á Dal and
Jökulsá í Fljótsdal with five dams, creating three
reservoir
A reservoir (; ) is an enlarged lake behind a dam, usually built to water storage, store fresh water, often doubling for hydroelectric power generation.
Reservoirs are created by controlling a watercourse that drains an existing body of wa ...
s. Water from the reservoirs is diverted through of underground water tunnels and down a 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
( )
is the centrepiece of the five dams and the largest of its type in Europe, standing tall with a length of and comprising of material.
The project has been heavily criticised for its environmental impact and its use of foreign workers.
Description
The
hydroelectricity
Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...
project harnesses the rivers Jökulsá á Dal and Jökulsá í Fljótsdal by creating three reservoirs with five
concrete
Concrete is a composite material composed of aggregate bound together with a fluid cement that cures to a solid over time. It is the second-most-used substance (after water), the most–widely used building material, and the most-manufactur ...
-face rock-filled
embankment dam
An embankment dam is a large artificial dam. It is typically created by the placement and compaction of a complex semi-plastic mound of various compositions of soil or rock. It has a semi-pervious waterproof natural covering for its surface ...
s; 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 (), the Desjará Dam
()
and the Sauðárdalur Dam
()
create the
Hálslón Reservoir. At tall and long, the Kárahnjúkar Dam is the largest dam in the project and the largest of its type in Europe as well. The tall and long Desjará Dam and the tall and long Sauðárdalur Dam are saddle or auxiliary dams that maintain the desired height of the Hálslón Reservoir. Water from the long, capacity Hálslón Reservoir (about the size of
Manhattan
Manhattan ( ) is the most densely populated and geographically smallest of the Boroughs of New York City, five boroughs of New York City. Coextensive with New York County, Manhattan is the County statistics of the United States#Smallest, larg ...
island in New York) is diverted down a long, diameter headrace tunnel towards the Fljótsdalur Power Station.
[Key Figures of the Kárahnjúkar Hydroelectric Project](_blank)
[The Kárahnjúkar Hydropower Project Overview](_blank)
On the river Jökulsá í Fljótsdal, the tall and long Kelduá Dam forms the capacity Kelduárlón Reservoir. Downstream from the Kelduá Dam is the tall, long Ufsarstífla dam which forms the Ufsarlón, a much smaller reservoir. Water from the Ufsarlón Reservoir is diverted down a long, diameter headrace tunnel where it joins the Hálslón Reservoir headrace tunnel.
Before each of the headrace tunnels from the Hálslón Reservoir or Ufsarlón Reservoir reach the underground power station, they both join to form a single combined headrace tunnel. The single headrace tunnel later splits into two long, diameter steel-lined
penstocks (tunnels) and the water makes a rapid descent down a final vertical penstock into the power station. The underground Fljótsdalur Power Station contains six vertical-axis
Francis turbine
The Francis turbine is a type of water turbine. It is an inward-flow reaction turbine that combines radial and axial flow concepts. Francis turbines are the most common water turbine in use today, and can achieve over 95% efficiency.
The pro ...
generators rated at 115 MW each. The power station has a combined capacity of 690 MW and discharge of (averages ) into the river Jökulsá í Fljótsdal via tailrace tunnels and canals. The power production of 4,600 GWh/year
corresponds to a
capacity factor
The net capacity factor is the unitless ratio of actual electrical energy output over a given period of time to the theoretical maximum electrical energy output over that period. The theoretical maximum energy output of a given installation is def ...
of 76%, which is relatively high for a hydroelectric facility. Power produced is then transmitted to Alcoa's Fjarðaál
aluminium smelter
Aluminium smelting is the process of extracting aluminium from its oxide, alumina, generally by the Hall-Héroult process. Alumina is extracted from the ore bauxite by means of the Bayer process at an List of alumina refineries, alumina refinery. ...
to the east in
Reyðarfjörður
Reyðarfjörður () is a town in Iceland. It has a population of 1,368 (2024) and is one of the most populated villages that constitute the municipality of Fjarðabyggð.
History
The town is at the bottom of the eponymous fjord
In physical g ...
.
Fjarðaál aluminium smelter
The Fjarðaál 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
A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...
. The
smelter
Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. It is a form of extractive metallurgy that is used to obtain many metals such as iron, copper, silver, tin, lead and zin ...
employs 450 people and produces 940 tons of aluminium a day, with capacity of 346,000 metric tons of aluminium per year. Fjarðaál means "Fjords Aluminium" in
Icelandic.
History
Using the rivers Jökulsá á Dal and Jökulsá í Fljótsdal along with other resources in eastern Iceland has been on the drawing board since the 1970s. From 1975 to 2002, several international companies had planned or attempted to build a metal plant at
Reyðarfjörður
Reyðarfjörður () is a town in Iceland. It has a population of 1,368 (2024) and is one of the most populated villages that constitute the municipality of Fjarðabyggð.
History
The town is at the bottom of the eponymous fjord
In physical g ...
that would be powered by a
hydroelectricity
Hydroelectricity, or hydroelectric power, is Electricity generation, electricity generated from hydropower (water power). Hydropower supplies 15% of the world's electricity, almost 4,210 TWh in 2023, which is more than all other Renewable energ ...
project similar to the Kárahnjúkar. All failed because of opposition to the project until Alcoa along with the
Government of Iceland
The politics of Iceland take place in the framework of a parliamentary system, parliamentary representative democracy, representative democratic republic, whereby the President of Iceland, president is the head of state, while the prime ministe ...
and
Landsvirkjun
Landsvirkjun, () the National Power Company of Iceland, is Iceland's largest electricity generator. Landsvirkjun operates 21 power plants in Iceland concentrated on five main areas of operation.
History
Landsvirkjun was founded on 1 July 196 ...
, Iceland's national power company committed to the massive project in 2002.
Construction

The project is funded by
Landsvirkjun
Landsvirkjun, () the National Power Company of Iceland, is Iceland's largest electricity generator. Landsvirkjun operates 21 power plants in Iceland concentrated on five main areas of operation.
History
Landsvirkjun was founded on 1 July 196 ...
, which operates the dams and Fljótsdalur Power Station. The Italian company
Impregilo is the largest contractor working on the dams. The total cost of the hydropower project is 1.3 billion
USD
The United States dollar (symbol: $; currency code: USD) is the official currency of the United States and several other countries. The Coinage Act of 1792 introduced the U.S. dollar at par with the Spanish silver dollar, divided it int ...
. The penstock was built in place by the
German
German(s) may refer to:
* Germany, the country of the Germans and German things
**Germania (Roman era)
* Germans, citizens of Germany, people of German ancestry, or native speakers of the German language
** For citizenship in Germany, see also Ge ...
company
DSD-NOELL (Würzburg) whereas ATB Riva Calzoni of Italy provided intake structures, wheels gates and sliding gates. In total, more than 4,000
ton
Ton is any of several units of measure of mass, volume or force. It has a long history and has acquired several meanings and uses.
As a unit of mass, ''ton'' can mean:
* the '' long ton'', which is
* the ''tonne'', also called the ''metric ...
s of steel were used for the steel liner.
Preparatory work on the project began in August 2002 and construction on the Kárahnjúkar 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 Desjará Dam and the Sauðárdalur Dam began in April 2004. In June 2006, construction of the Kelduá Dam and Ufsarstífla Dam began and in September, the
Hálslón Reservoir began to fill. In mid-2008, the Kelduá and Ufsarstífla Dams were complete and the Ufsarlón Reservoir headrace tunnel was ready.
Construction on the headrace tunnels was done by three full-face
tunnel boring machine
A tunnel boring machine (TBM), also known as a "mole" or a "worm", is a machine used to excavate tunnels. TBMs are an alternative to drilling and blasting methods and "hand mining", allowing more rapid excavation through hard rock, wet or dry so ...
s, while remaining areas were drilled and blasted.
This was the first time that tunnel boring machines were used in Iceland.
There were several workplace fatalities during the construction process including: Arni Thor Bjarnason, Eilifur Gopi Hammond, Ludvik Alfred Halldorsson and Kresimir Durinic.
Criticism
The dams have been the frequent subject of protests by
environmentalists
Environmentalism is a broad philosophy, ideology, and social movement about supporting life, habitats, and surroundings. While environmentalism focuses more on the environmental and nature-related aspects of green ideology and politics, ecologi ...
for many reasons. The area is within the second largest (formerly) unspoiled wilderness in Europe and covers about in total and the rivers that supply water to the project are part of Europe's largest glacier,
Vatnajökull
Vatnajökull ( Icelandic pronunciation: , literally "Glacier of Lakes"; sometimes translated as Vatna Glacier in English) is the largest and most voluminous ice cap in Iceland, and the second largest in area in Europe after the Severny Island i ...
. About 70% of the workforce was composed of foreign workers. For the construction of Kárahnjúkar Hydropower Plant in East Iceland, five dams in two glacial rivers created three reservoirs, that together flooded over 440,000 acres of unspoilt Highland territory. The megastructure is on a scale like nothing the nation has seen before or since and, as such, has been a constant source of protest and controversy due to the landscapes irretrievably lost. The total affected area according to the environmental impact assessment, outlines that a total of 3,000 km
2 or 741,316 acres were affected by the project's construction. That is approximately 3% of Iceland's total land mass.
Representation in film and literature
The project as a whole was criticised heavily in the 2006 book ''
Draumalandið'' and subsequent 2009
documentary
A documentary film (often described simply as a documentary) is a nonfiction Film, motion picture intended to "document reality, primarily for instruction, education or maintaining a Recorded history, historical record". The American author and ...
''
Dreamland''. The project was documented in a ''
MegaStructures'' program of the
National Geographic Channel
National Geographic (formerly National Geographic Channel; abbreviated and trademarked as Nat Geo or Nat Geo TV) is an American pay television network and flagship channel owned by the National Geographic Global Networks unit of Disney Enter ...
, and the
Discovery Channel
Discovery Channel, known as The Discovery Channel from 1985 to 1995, and often referred to as simply Discovery, is an American cable channel that is best known for its ongoing reality television shows and promotion of pseudoscience.
It init ...
's ''
Extreme Engineering'', along with mention in the 2006
Sigur Rós
Sigur Rós () is an Icelandic post-rock band that formed in 1994 in Reykjavík. It comprises lead vocalist and guitarist Jónsi, Jón Þór "Jónsi" Birgisson, bassist Georg Hólm, and keyboardist Kjartan Sveinsson. Known for their ethereal soun ...
rockumentary ''
Heima
''Heima'' (; ''at home'') is a documentary film and double DVD set about the tour around Iceland in the summer of 2006 of the band Sigur Rós. During the tour the band played two big open-air concerts at Miklatún - Reykjavík (30 July) and Ásbyr ...
'' (At Home), where the band played at a protest against the building of the dam. The dam has been read as an inspiration for a mysterious dam in
Steinar Bragi's horror novel ''
Hálendið''.
See also
*
Economy of Iceland
*
Renewable energy in Iceland
Iceland is a world leader in renewable energy. 100% of the electricity in Iceland's electricity grid is produced from renewable resources. In terms of total energy supply, 85% of the total primary energy supply in Iceland is derived from domesti ...
*
Hydroelectricity in Iceland
References
External links
Kárahnjúkar HEP Overview – Landsvirkjun – September 2009Anti-dam website*
ttp://islandsmyndir.is/html_skjol/annad/Virkjanir/Karahnjukavirkjun-2006-06-28/index.html Kárahnjúkar – 2006 – picture gallery from islandsmyndir.isKárahnjúkar – 2007 A – picture gallery from islandsmyndir.is*
ttp://islandsmyndir.is/html_skjol/annad/Virkjanir/Karahnjukavirkjun-2008-07-24/index.html Kárahnjúkar – 2008 – picture gallery from islandsmyndir.isKárahnjúkar – Hringiða, 2011 – picture gallery from islandsmyndir.is
{{DEFAULTSORT:Karahnjukar Hydropower Project
Energy infrastructure completed in 2009
Hydroelectric power stations in Iceland
Alcoa
Underground power stations
Eastern Region (Iceland)