Project design
The key to the efficiency of the power plant is its geographical situation. Fljótsdalur valley lies very low and cuts into the highland plateau north of the Vatnajökull glacier.
Such advantageous circumstance means a considerably high head when the glacial rivers are harnessed lower down in the valley. The total head from Hálslón to Fljótsdalur is approximately 600 m. Kárahnjúkar harnesses both glacial rivers from an elevation of 625 metres to an elevation of 26 m at Valthjófstadur in Fljótsdalur.
The Kárahnjúkar project generates 690 MW using six generating units. The maximum flow through the headrace tunnels is approximately 144 m³ per second, and the generating capacity is 4,600 GWh per year.