High in the Swiss Alps, a massive new pumped hydropower storage plant acts like a giant rechargeable battery to stabilize electricity supplies. The Nant de Drance facility can store enough energy to power 400,000 EVs and provides a blueprint for global expansion of renewable energy.
An Enormous ‘Water Battery‘ in the Swiss Alps
On July 1, 2022, the colossal Nant de Drance Hydropower Plant switched on, culminating over 14 years of construction by a consortium of top Swiss utility and rail companies.
The $2 billion project, Switzerland‘s largest ever, transformed two existing reservoirs in the mountain cliffs south of Martigny into a potent ‘water battery‘. By harnessing the power of gravity and water, Nant de Drance stabilizes electricity supplies across Europe.
How Nant de Drance Works
The basic principle resembles a rechargeable battery:
- Two large reservoirs sit at different elevations, connected by a subterranean engine room
- Use cheap, surplus electricity to pump water uphill into the upper basin
- When power is needed, release water to drive turbines producing up to 900 MW
This simple concept provides enormous grid flexibility. In seconds, the plant can switch from pumping to generation, reacting to fluctuations in renewable supplies or demand.
The facility also stores a massive 20 gigawatt hours (GWh) using the mountain lakes – enough to power Switzerland‘s entire rail network for 45 days!
Key Nant de Drance Statistics
| Specification | Detail |
|---|---|
| Water storage capacity | 20 GWh |
| Power generation capacity | 900 MW |
| Round-trip efficiency | 80% |
| Upper reservoir capacity | 25 million m^3 |
| Tunnels excavated | 64 km |
| Construction time | 14 years |
| Construction cost | $2 billion |
Supporting the Renewable Energy Transition
Across Europe, utilities must rapidly scale up solar and wind generation to meet sustainability goals while phasing out nuclear and fossil fuels. The transition brings a major challenge – balancing intermittent renewable supplies.
Nant de Drance‘s enormous storage capacity guarantees power, even when the sun isn‘t shining and wind isn‘t blowing. By storing huge amounts of energy, it balances generation from unpredictable renewable sources.
The Swiss facility sets a new bar for advanced pumped hydro storage. Let‘s examine why the technology causes such excitement.
Why Pumped Hydro Offers an Ideal Storage Solution
Engineers categorize grid storage methods into three main groups:
Electrical – batteries, capacitors
Mechanical – pumped hydro, compressed air, flywheels
Chemical – hydrogen, synthetic methane
Batteries grab headlines with giant projects from Tesla and others under development. However, for bulk energy storage, pumped hydro has unmatched potential globally.
Key Benefits of Pumped Hydropower
Scalability – facilities sized from under 100 MW to over 3,000 MW
Efficiency – modern systems up to 85% efficient
Affordability – low lifetime costs despite high initial spending
Sustainability – uses mostly existing geography, minimal materials
Reliability – proven technology with 50+ year system lifetimes
Crucially, pumped storage works irrespective of battery technology advances. It relies on simple, durable hydropower equipment. Innovation focuses on software controlling generation and grid interconnection.
Let‘s look at how Nant de Drance put these strengths into an award-winning design.
Inside Nant de Drance: By the Numbers
While the Swiss plant resembles over 200 existing pumped hydro facilities, its scale sets new records.
Constructing the gigantic ‘water battery‘ challenged engineers to the extreme. The project excavated tunnels through solid Alpine granite equal to the volume of Egypt‘s great pyramid. Workers faced frigid temperatures and dizzying mountain terrain throughout the 14 years of construction.
Nant de Drance Construction Statistics
| Specification | Detail |
|---|---|
| Excavation | 2 million m^3 |
| Construction workforce | >650 workers |
| Companies involved | ~60 contractors |
| Access tunnels | 11 miles |
The challenging location arises from existing hydropower infrastructure. Built between 1921-25, the lower Lac d‘Emosson reservoir gained a heightened dam in 1973. Later, the mountainside Vieux Emosson lake above added further capacity.
For the Nant de Drance project, builders partially drained and strengthened these dams. They also added giant intake towers to feed water into new underground penstocks. Workers mated these pipes to six turbine-pump systems in one of the world‘s most cavernous machine halls – spanning an incredible 8 acres.
Scale of the Underground Infrastructure
| Specification | Detail |
|---|---|
| Upper reservoir expansion | Double capacity – 25 million m^3 total |
| Penstock pipes (2) | 156 m tall, 6 m diameter |
| Underground caverns | 46,000 m2 |
| Francis pump/turbines | 6 x 150 MW |
This infrastructure allows fast switching between pumping water uphill and driving it downhill to generate power. An advanced control system assists operators in optimizing the complex flows.
By integrating latest software with robust hydro equipment, Nant de Drance achieves 80% round-trip efficiency, making it one of the global leaders.
And the project puts Switzerland firmly on the energy storage map.
How Nant de Drance Stacks Up Globally
Pumped hydro plants already supply 97% of worldwide utility storage – virtually all growth in the last 20 years used this technology. Modern variable-speed designs now challenge even lithium-ion batteries on performance.
Nant de Drance enters the stage as one of the world‘s largest.
Leading Global Pumped Hydro Plants
| Plant | Country | Capacity | Year Complete |
|---|---|---|---|
| Bath County | USA | 3,003 MW | 1985 |
| Guangzhou | China | 2,400 MW | 2016 |
| Tianhuangping | China | 1,800 MW | 2021 |
| Huizhou | China | 1,500 MW | 2017 |
| Nant de Drance | Switzerland | 900 MW | 2022 |
| Vianden | Luxembourg | 1,096 MW | 1964 |
| Fengning | China | 1,200 MW | 2014 |
With 24 GWh storage atop 900 MW capacity, Nant de Drance even surpasses China‘s prolifically built sites on critical storage duration. New variable speed turbine designs also increase efficiency.
The Swiss colossus showcases European engineering prowess at its best. Yet bigger still lies in wait as the continent – and world – races towards carbon neutrality.
Global Potential: 23 Million GWh in Water Batteries
Currently, only 166 GW of pumped hydro exist globally – less than 2% of estimated capacity. The International Renewable Energy Agency modeled the geographic potential based on terrain and bodies of water.
They found over 600,000 promising sites for closed-loop pumped storage plants like Nant de Drance. Harnessing even a fraction of these locations could enable enormous growth of solar and wind power to combat climate change.
Global Potential for Pumped Hydro Expansion
| Metric | Estimate |
|---|---|
| Geographic sites | >600,000 globally |
| Capacity potential | 23 million GWh |
| Output potential | 100 terawatts |
Dwarfing even Nant de Drance, China has 4.2 million GWh theoretically available, Australia 2.4 million GWh, and the United States 2.1 million GWh using closed-loop reservoirs alone.
So while batteries grab headlines with Tesla‘s new gigafactories, pumped storage looks more than ready to underpin the entire renewable revolution.
Nant de Drance merely provides an inspirational glimpse at the future for sustainably storing vast amounts of green energy globally. Perhaps millions more water batteries will soon join it.
