Dutch saltwater battery innovation announced as finalist in 2025 European Sustainable Energy Awards

How can table salt and water help address Europe’s dependence on raw materials and strengthen renewable energy supply? A pilot in Delft, in the Netherlands, may soon be able to commercialise the world’s most sustainable, affordable and scalable long duration energy storage solution based on saltwater.

Long duration energy storage (LDES) is key to achieving the EU's 2030 energy and climate goals by enabling the integration of renewable energy sources like wind and solar into the grid, explains Jiajun Cen, co-founder and CEO of AQUABATTERY – the company behind the saltwater battery pilot. LDES allows excess energy generated during periods of high renewable output to be stored and used during periods of low generation, ensuring a stable and reliable power supply. 

The saltwater flow battery goes one step further: 

'By using table salt and water – abundant and environmentally friendly materials – we can eliminate Europe’s dependence on critical raw materials, avoid the environmental destruction caused by open-pit mining of lithium and rare earth, and eliminate the fire, toxicity, and explosion risks to people and habitats near battery sites,' Cen explains.

During charging, renewable electricity converts saltwater into acid and base, split between separate tanks, in a process that stores the electricity. When discharging, the acid and base solutions recombine into saltwater, generating electricity.

With funding from the European Innovation Council and five paying partners drawn from the energy, housing, and commercial building sectors, AQUABATTERY last November launched a pilot in Delft, near the Dutch port of Rotterdam, testing the largest and most advanced saltwater flow battery ever built in Europe. The battery uses locally sourced raw materials (table salt, water) and components (piping, tanks), ensuring higher resilience, lower carbon emissions, and regional economic growth. The site will operate for 12 months, generating key insights to accelerate product development, aiming for market readiness by 2026.

AQUABATTERY is working closely with its pilot partners to identify which business cases are most suitable for deployment.

 'We are seeing strong interest from the commercial and industrial sectors, where the urgency to decarbonise, reduce electricity costs, and increase independence from the grid is particularly high,' says Cen.

Such clients could include factories, logistics centres, water treatment plants, energy hubs, port terminals, hospitals, and large housing or office real estate developments. 

'Their needs are to reduce electricity bills, increase electricity usage despite grid congestion, better utilise existing solar PV production, and provide backup power in the event of a blackout. And they want to do this using a safe and sustainable battery technology that does not introduce additional risks to their operations or personnel.'

The technology can be configured for any storage duration by simply adding more saltwater and tanks. Typically, long-duration energy storage operates within a range of 8 to 100 hours, Cen explains. 

'Our pilot project in Delft is designed for a 10-hour duration, but we remain flexible and can extend the duration to meet specific client needs.'

The saltwater battery pilot demonstrates a 5 tonne CO₂ equivalent reduction in embodied carbon emissions compared to lithium battery technology, with the company claiming it could achieve additional annual carbon savings of 7 metric tons of CO₂ if operated as a commercial project on the Dutch grid.

'By developing a European energy storage solution, AQUBATTERY strengthens the EU's strategic autonomy,” says Cen. “This not only fosters energy security but also enhances the EU's competitiveness in the global clean energy market. This project was made possible by the contributions of our partners Deltares, Statkraft, Verbund and Central Agency for the Reception of Asylum Seekers'

EUSEW Awards ​celebrate Europe’s best clean energy projects and leaders 

AQUABATTERY is one of three finalists shortlisted for the European Sustainable Energy Awards 2025 in the Innovation category. The award recognises outstanding ongoing or recently completed EU-funded projects that show an original and innovative path towards the clean energy transition. The other finalists in this category are the LIFE4GREENBROADBAND project in Croatia, and the LIFE TURBINES project in Spain and Italy.

LIFE TURBINES is using hydropower to generate electricity by harnessing excess pressure in domestic water supplies. LIFE4GREENBROADBAND is cutting emissions in the telecoms sector by rolling out cooling and solar power solutions at base stations.

The European Sustainable Energy Awards ​ (EUSEW Awards) recognise outstanding individuals and projects for their innovation and efforts in energy efficiency and renewables. The nine finalists have been selected by a high-level jury in three categories: Innovation, Local Energy Action, and Woman in Energy. The finalists will be submitted to an online public vote, which is open  until 1 June, and the winners will be announced during the EUSEW Awards Ceremony on 10 June 2025. ​  ​ ​  

EUSEW 2025  

European Sustainable Energy Week (EUSEW), the​ biggest annual event dedicated to renewables and efficient energy use in Europe, takes place on 10-12 June under the theme of ‘Powering a fair and competitive green transition’. The event will bring together public authorities, industry, NGOs and consumers to promote initiatives accelerating decarbonisation through clean technologies and solutions towards a competitive, fair and just transition both for people and businesses.

Registrations for onsite attendance in Brussels and online participation are  now open.  

For interview requests with the EUSEW Awards finalists or additional media information, please contact ​ mediaeusew [dot] eu