This giant ‘water battery’ under the Alps could be a game-changer for renewable energy in Europe
Located in the heights of the Swiss Alps, in the canton of Valais, the plant is equipped with agile and reversible turbines which offer new levels of flexibility, explains Robert Gleitz, delegate of the board of directors of Nant de Drance: from a simple pressing a switch, the plant can switch from energy storage to electricity supply.
The massive project lasted 14 years. Around 17 kilometers (10.5 miles) of underground tunnels have been dug through the Alps while the six turbines are stored 600 meters (1,970 feet) underground, in a giant cave the length of two football pitches.
Nant de Drance has redeveloped two existing reservoirs, raising the upper reservoir by 21.5 meters (71 ft) to double its capacity – it now holds more water than 6,500 Olympic swimming pools.
As one of the largest facilities of its kind, the $2 billion project could play a vital role in stabilizing Europe’s power grid as the continent transitions to renewable energy, says Gleitz.
To make a sensation
Pumped-storage hydropower plants, which have been around for more than a century, are particularly important for renewable energy because wind and solar are highly dependent on weather conditions and do not provide a constant power supply.
“We can take power (from the grid) when there is too much and generate it again when needed,” says Gleitz.
Unlike many plants that preceded it, Nant de Drance uses variable-speed pump-turbines, explains Pascal Radue, CEO of GE Renewable Energy Hydro, which supplied the equipment for the installation.
Turbines help stabilize the power grid, Radue says.
“With a fixed-speed turbine, you have to wait for the power plant to spin at exactly the right speed to get in sync with the grid,” Radue says, adding that this wastes time and energy. Variable-speed turbines immediately supply electricity to the grid, reducing the risk of outages.
A big impact
That’s why modern projects favor closed-loop systems, like Nant de Drance, that don’t impact river systems, says Andrew Blakers, professor of engineering at the Australian National University.
“The era of building dams is almost over,” says Blakers, adding that these closed-loop power plants occupy a relatively small space given the energy security they provide. He estimates that to power a city of one million people for 24 hours would require about two square kilometers of flooded land, adding that pumped storage hydroelectricity offers one of the most efficient energy storage solutions available today.
Nant de Drance sends around 80% of the electricity it harvests back to the grid and stores around 20 hours of backup power, says Gleitz.
Transition to renewable energies
This is why Nant de Drance is so significant. Located at the geographic heart of Europe, Switzerland could provide grid stability across the continent, says Rebecca Ellis, head of energy policy at the nonprofit International Hydropower Association. Nant de Drance has increased Switzerland’s installed energy capacity by 33%, says Ellis, adding that it “shows Switzerland’s leadership” in the transition to renewable energy.
However, since the country is not a member of the European Union, regulations are currently an obstacle, says Gleitz. “Market rules are not easy,” he says. “We still need closer agreements with the EU.”
As the climate crisis intensifies, Gleitz hopes Europe will embrace the potential for “clean energy storage” provided by pumped-storage hydroelectric power plants. “If we want to go in the direction of having clean energy, Nant de Drance is one of the springboards on this path”, he specifies.