The push to keep Europe’s electricity grid stable has gained a huge new ally beneath Swiss ground. An enormous cavern has been excavated to house what is set to become the world’s largest underground battery, aiming to transform clean storage of renewable energy.
What is the true scale of this underground project?
The build is striking in size, matching roughly two football pitches placed together. The excavation reaches about 27 metres deep, forming a solid foundation for a high-tech complex that reshapes the electrical infrastructure of central Europe.
Below ground, this hub contains heavy-duty equipment engineered by FlexBase. The design accommodates vast tanks and modern converters, with core technical attributes that enable safe operation of the full energy system through the following innovative storage resources:
- Electrical power: Ability to dispatch up to 1.2 GW to the power grid immediately.
- Planned capacity: Total storage designed to exceed 2.1 GWh of energy.
- Physical footprint: The full above-ground campus covers more than 40,000 m².
- Initial connectivity: Swissgrid has approved the first stage at 800 MW.
- Residential supply: Enough autonomy to power around 210,000 homes.
How does redox flow technology work?
Unlike conventional lithium-ion models, this system relies on liquid electrolytes stored in large reservoirs. Electricity is converted into chemical energy within the tanks, and the process is reversed on demand precisely when the grid needs steady support.
This industrial setup makes it possible to scale capacity by increasing only the volume of the metal tanks. The plant uses a recyclable, water-based aqueous solution with a high water content, delivering dependable operation and avoiding risks associated with explosions or fires at the power station.
Who are the strategic partners involved?
Bringing a project of this scale to life depends on high-level corporate collaboration and international technical expertise. FlexBase’s leadership has put key agreements in place to secure the right technology supply, highlighting the corporate partnership below that is driving development of this formidable battery structure:
| Strategic partnership | Details |
|---|---|
| Invinity Energy Systems | The company was formally chosen in May 2026 to provide the vanadium flow technology required for the project. Its initial work covers delivering a robust platform of up to 1.5 GWh, with plans for later expansion. |
FlexBase’s chief executive, Marcel Aumer, also reinforced the importance of this corporate choice because of the operational stability it provides. Beyond the built-in safety, the deciding factors behind this commercial alliance include the following highlighted operational advantages:
- Complete non-flammability of the chemical components used.
- Strong cycle stability over time.
- Practical flexibility for grid regulation applications.
What additional benefits will the centre deliver?
Technology Center Laufenburg will operate as more than a simple energy store for the grid. The modern complex will also include administrative offices, advanced research laboratories, and a water-cooled, modern data centre focused on processing next-generation artificial intelligence.
This large-scale computing integration makes it possible to use locally produced resources intelligently. Heat recovery will create an environmentally positive dynamic for the surrounding area, offering direct benefits that can be clearly summarised through these sustainability impact points:
- Direct supply to an urban district-heating network.
- Estimated saving of 82,000 tonnes of carbon dioxide.
- Local creation of around 300 new long-term jobs.
What is the expected timeline and cost?
The total financial commitment is substantial, with estimates ranging between CHF 1 billion and CHF 5 billion. This fully private funding ensures the civil works can progress without placing any burden on the public budget of government or local citizens.
Full commissioning is expected between 2028 and 2029. That window reflects the complex staged work required to deliver infrastructure of such importance to the energy future.
Reference: Invinity Energy Systems has emerged as the strategic partner for the world’s largest flow battery storage facility in Laufenburg, Switzerland | FlexBase
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