Assessing the Power Potential

In order to be able to assess the potential amount of hydroelectric power at a particular location, knowledge is required of the flow of water from the lakes that collect meltwater and rainwater from the surrounding fells and the Ice Sheet.

Measuring equipments has been installed around the different hydropower potential sites (Photo: Greenland Development)

The lakes, which are called reservoirs, act like a rechargeable battery. The "battery" is charged up with meltwater and rain during the summer (the water head rises). Because water is consumed in the hydroelectric power station all year round, the "battery" is discharged (the water head in the reservoir falls) during the winter when precipitation falls as snow, and the low temperatures prevent the water from running into the reservoir.

• Asiaq (Greenland Survey) operates hydrological measurement stations at several of the most important hydropower potentials in Greenland. These devices measure precipitation and water head. On the basis of the data acquired by the measurement stations, engineers can calculate the volume of water that flows through the lakes during a one-year period.
• The area of the lake is surveyed and the depth of the water determined by means of an echo sounder, which enables the total volume of the lake to be calculated. At the same time, a location where the water is as deep as possible is identified as the location for the intake to the tunnel through which the water is led to the hydroelectric power plant.
• The ability to dam up the lake (raising the potential water head) is a very important factor in terms of increasing the lake's maximum volume of water and thereby increasing the capacity of the "battery".

Dams also increase the drop of the water, thus ensuring better energy utilization of the volume of water which is in the lake.

The above surveys take place prior to commencing the construction of hydroelectric power plants, and it is important to know the possible fluctuations in precipitation and meltwater year on year. If the weather in a particular year is cold and precipitation is low, this may result in a hydroelectric power station having to run at reduced output in order to avoid emptying the reservoir of water during the winter. This risk is best countered by ensuring that the reservoirs have sufficient capacity to cope with a prolonged period with a low inflow of water.

In order to ensure that forecasts concerning future water volumes in the lakes are as accurate as possible, it is important to have data available that has been acquired over many years when calculating the potential reserves of power and when planning construction work. The measurements that are performed today may thus prove to represent a vital contribution to decisions concerning hydroelectric power stations in 20 years' time. For each lake, including Tasersiaq, Asiaq has hydrological data which dates all the way back to the mid-1970s.

Read more about hydrology and Asiaq's work at: Asiaq