The Controversial Kárahnjúkar Dam

The Controversial Kárahnjúkar Dam

Kárahnjúkar Power Plant is by far the largest power plant in Iceland and the largest construction project ever undertaken in the nation's history. The plant has a power output of 690 MW, which is similar to the combined output of all the power plants in the rivers Ţjórsá and Tungnaá.


Hafrahvammagljúfur canyon was among the natural phenomena that disappeared with the construction of the Kárahnjúkar Dam and now lies submerged at the northern end of the Hálslón reservoir. The Kárahnjúkar Power Plant is by far the largest construction project in Icelandic history. With a power output of 690 MW, the plant generates as much energy as all the power plants in the rivers Ţjórsá and Tungnaá combined.

The plant harnesses the flow of two glacial rivers at the same time. Water from the rivers Jökulsá á Dal and Jökulsá í Fljótsdal is diverted into a tunnel at Valţjófsstađafjall mountain in Fljótsdalur. The tunnel runs 70 km at 500 m above sea level before reaching a shaft where the water plummets into station facilities at 30 m above sea level.

Dams east of Snćfell mountain are used to divert the water of the river Jökulsá í Fljótsdal to the station facilities, whence they are rediverted back to the river course.

Three large dams at Kárahnjúkar divert the water of the river Jökulsá á Dal along with that of its powerful tributary, the river Kringilsá, 40 km to the river Jökulsá í Fljótsdal and the 57 km2 Hálslón reservoir.

In its initial conception, the Kárahnjúkar Power Plant formed part of an even bigger plan that involved harnessing the flow of the river Jökulsá á Fjöllum by diverting its flow, too, into the Hálslón reservoir. This plan was nicknamed the "Grandest Plan" (Lang-Stćrsti Draumurinn in Icelandic, abbreviated LSD). A similar plan was being considered for the Norway Highlands, but came to nothing due to environmental impact, which would nevertheless have fallen short of that in the northern Iceland Highlands.

Both of these grandiose schemes aimed to harness the immense energy potential of rivers at high altitudes.

Shortly after construction started at Kárahnjúkar, it was revealed in the 1st phase of the Master Plan for Hydro and Geothermal Energy Resources that the Kárahnjúkar Power Proposal was one of the two proposals with the most environmental impact, the other being the damming of the river Jökulsá á Fjöllum.

Despite this, there is pressure from hydroelectricity enthusiasts for the construction of the so-called Helmingur Power Plant which would entail the exploitation of the river Jökulsá á Fjöllum in a similar way to that outlined in the "Grandest Plan".

The Kárahnjúkar Power Plant is an excellent example of the high-risk speculative mentality that dominated the Icelandic economy in the period 2002-2008. A lawyer at Landsvirkjun let it drop that the proposal was "a difficult and risky endeavor geographically, technologically, environmentally and economically,... an isolated case in the energy sector…".

It was not immediately apparent whether it would be viable to dig a waterproof tunnel through an intervening 6-7 km stretch of fault lines. However, research on the feasibility of the tunnel was purposefully not carried out, as this part of the construction was only to be carried out towards the end of the project.


Read more about Kárahnjúkar Dam on Nature Iceland.


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