Tasersiaq is Greenland's longest lake and it is located approximately 100 km south of Kangerlussuaq. The lake's surface lies approximately 682 metres above sea level. Due to the high mountains that encircle the lake, it has a relatively small ‘catchment area’ (the area of land from which rainfall flows into the lake). The lake's most important water source is melted ice from glaciers at the lake’s eastern and southern end. This means that the water is filled with silt particles from the glaciers and the lake has no fish life.
To utilise the potential in the best possible way, the water from Tasersiaq will be directed to the southwest, through a tunnel about 30 km long to a power plant in the inner part of Eternity Fjord.
In the earliest engineering studies from the 1970s, it was envisaged that a tunnel would follow the natural flow of the river northwest to Paradise Valley, which flows into Kangerlussuaq.
However, there are both natural and technical reasons why a tunnel towards Eternity Fjord is preferable. You can avoid permanent constructions in the protected Paradise Valley and achieve both short tunnelling and greater height difference between the lake and the power plant.
Other construction works include two dams, where the highest will probably require a height of up to 37 metres.
The main reason why Tasersiaq should be raised from its current level is the size of the reservoir: A larger and deeper lake ensures a continuous water supply to the tunnel in winter and the lake’s capacity will compensate for lower inflow of rain and melt water in cold and dry years. Studies of the lake have also shown that it is quite shallow in some places.
The drop from the lake to fjord level would be 709 metres when the reservoir is full. The surface area will be approximately 190 km2 with a maximum change in the water level of 24 metres.
The illustration below shows the size of Tasersiaq at maximum water levels with the dams installed. The circumference of the natural lake is indicated by a red line.
Based on the last 20 years of water flow data, Tasersiaq appears to have a larger energy potential than originally expected. This compensates for the major engineering challenge by establishing a hydroelectric power plant, tunnel and dams in such a secluded spot. Tasersiaq is without question Greenland’s most attractive hydroelectric potential.
Expected energy capacity for Tasersiaq: 475-500 MW of continuous power.