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.

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 (300×106 cu ft) of material.

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

Source: https://en.wikipedia.org/wiki/K%C3%A1rahnj%C3%BAkar_Hydropower_Plant

Image: www.islandsmyndir.is