Potentially Helpful Lakes Left Behind Melting Glaciers
As glaciers melt and retreat they often leave behind massive lakes of fresh water where once had been only ice. Now, a student from the École Polytechnique Fédérale de Lausanne in Switzerland has studied the possibility of using these new lakes as possible hydroelectric power sources.
Climate change has seen glaciers all over the world retreating, shedding layers like a grumpy cat sheds fur. Several scenarios are picturing an average temperature increase of 4°C, which would see glaciers disappear entirely by the end of this century.
“Glaciers store water and transfer winter precipitation into summer runoff,” said Anton Schleiss, director of EPFL’s Hydraulic Constructions Laboratory and a member of a Swiss National Science Foundation research project into the risks and possibilities of these new mountain lakes. “Once they have disappeared, we will need to manage these new reservoirs, which will take over this water storage role.”
But it was EPFL Civil Engineering student David Zumofen who studied several options for how the new natural reservoirs could be used to produce electricity, focusing his attention on Rhone glacier in the Swiss Alps.
The first scenario involves the lake water passing through turbines on the site as part of the construction of a future Gletsch-Oberwald hydroelectric power plant. Though this option would yield less energy, it would not require altering any existing structures between the nearby river the Rhone and Lake Geneva.
The second scenario uses existing hydroelectric structures in place in Oberhasli, on the other side of the Grimsel Pass, at the drainage divide between the Rhine and Rhone watersheds. The water can thus pass through existing turbines several times on its journey downstream, making this option the cheaper and more energy productive option.
However, the second option also deprives the Rhone from a valuable source of water.
The Rhone glacier has lost 6 percent of its mass in only the last ten years., 150 years ago it covered the entire Gletsch valley, but today, it’s tongue has retreated far up the watershed.
Previous studies have found two large cavities beneath the glacier, each more than 50 metres deep. One of these cavities may be completely revealed by 2065, allowing for the possibility of hydroelectric power.
“We must be careful about making climate predictions, because what was true a century ago may well no longer hold 100 years from now,” says Zumofen. “If current predictions are correct, however, one of the two lakes could hold up to 50 million cubic meters of water.”