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A gigantic rechargeable battery


Generating electricity when the sun does not shine or the wind does not blow poses a challenge for the world’s transition to renewable power. A twist on a century-old technology offers an elegant solution. Pumped storage hydropower uses gravity to store massive amounts of green energy and generate electricity on demand. At Nant de Drance in the Swiss alps, molybdenum-alloyed high strength steels are crucial to keep electricity flowing.

© Nant de Drance, Sébastien Moret

Among renewable energy sources, solar and wind are considered the most viable to reduce greenhouse gas emissions by 2050, according to the International Energy Agency. However, the availability of both depends on the course of nature, making electricity supply variable, unlike that from fuel burning power plants. For instance, if a very windy day produces more power than needed, that power is wasted without adequate storage. A mismatch in supply and demand puts communities at risk of black outs or power surges. Hydropower storage, also known as pumped storage, offers both a solution and an alternative to massive utility-scale battery banks. When there is excess electricity in the power grid, it is used to pump water from a lower reservoir into a second reservoir at a higher elevation, like recharging a giant battery. When demand necessitates, the water is released and uses gravity to drive a turbine, producing electricity. Currently, pumped storage is the largest battery technology by far, representing over 90% of all installed energy storage capacity globally, according to the International Hydropower Association. The amount of energy stored in the world’s hydropower plants dwarfs all traditional batteries on earth combined, including all electric vehicles (EVs).

© Nant de Drance, Sébastien Moret

Building a plant in the Swiss alps

Pumped storage isn’t appropriate for every environment: droughts, for example, can severely compromise the system’s function. Hydropower technology can also affect sensitive ecosystems. And there must be a significant elevation difference for water to fall from: the greater the difference, the more energy efficient. But in areas with ample space, water, and mountains where a height difference can be exploited, pumped storage offers immense potential to compensate for fluctuations in power supply and demand. According to Australian National University, there are over 600,000 sites potentially suitable for pumped storage systems worldwide.

A good use case for pumped storage lies in Switzerland, which already generates nearly all of its electricity with carbon-free hydro and nuclear power. Around 60% comes from hydropower and an additional 35% comes from nuclear. Though the country has among the lowest carbon emissions in electricity generation worldwide, its ability to transition away from nuclear generation to renewables depends on large scale storage solutions. Bringing Nant de Drance online provides storage capacity, generates low carbon electricity, and adds system flexibility. The plant is crucial not only for stabilizing the Swiss grid but also for the European electric grid at large. For example, if a wind farm in Germany produces an excess supply, that energy can be transferred and stored at Nant de Drance.

Discover how Nant de Drance is made more reliable and longer lasting through the special properties of molybdenum-alloyed high-strength steels. It is clear that molybdenum is, once again, instrumental in a technology poised to meet the world’s energy demands more sustainably.

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