Solar and wind need storage that can hold energy for many hours, cheaply and safely. AquaBattery, a Dutch company in Alphen aan den Rijn, builds a flow battery that uses table salt and water. It says the system is non-flammable, uses "non-critical material" and can store energy "anywhere from 8 hours onwards".
The European Innovation Council granted €2,263,405 towards a €3.23 million project to improve the battery stack, which ran from April 2022 to February 2025. In November 2024 AquaBattery launched a pilot with 10 hours of storage at the Deltares campus in Delft, with Statkraft and Verbund among the partners. Its news page since then shows awards, consortia and a letter of intent, but no sale.
Company file
- Legal entity
- AquaBattery BV, Alphen aan den Rijn, Netherlands
- CEO
- Jiajun Cen
- Technology
- Salt-water flow battery for long-duration storage
- Pilot
- Deltares campus, Delft; partners Statkraft, Verbund, COA; support from Invest-NL
- Consortia
- SLDBatt (Growth Fund, 2025); RenewaFLEXNL (2026)
- Award
- European Sustainable Energy Award 2025
- EIC project
- AquaBattery, 1 Apr 2022 to 28 Feb 2025, closed
- EIC funding
- Grant first
Where AquaBattery Stands Today
AquaBattery is a partner in SLDBatt, a Dutch consortium led by the University of Twente that won more than €20 million from the national Growth Fund in November 2025 to develop batteries for 8 to 100 hours of storage, with partners including RWE and Nobian. In October 2025 it signed a letter of intent with Sciven, and in February 2026 joined the RenewaFLEXNL consortium on long-duration storage use cases. In June 2025 it won the European Sustainable Energy Award. It has not announced a commercial order.
The Technology: Acid, Base and Salt
AquaBattery's flow battery keeps its energy in liquid tanks, so storage duration grows by "adding tanks with table salt and water". The CORDIS report describes new spacer designs and clamping methods, a membrane pre-treatment partnership that cut cutting costs by 50% and assembly time by 60%, a 25% reduction in steel weight, and a targeted 25% gain in energy density. It says "a previous version of membrane stack was tested at a pilot location in the Netherlands".
"Increasing storage duration is as simple as adding tanks with table salt and water."
AquaBattery websiteWhat the EIC Project Promised, and What CORDIS Shows
The project promised "a 100% sustainable and infinitely scalable electrical energy storage system". CORDIS reports engineering improvements and lab and pilot testing, but no system size in kilowatt-hours, efficiency, cycle life or customers.
- A better battery stackDeliveredNew spacers, clamping, lighter steel.
- Lower production costDelivered50% cheaper cutting; 60% faster assembly.
- Field pilotDeliveredDelft pilot, 2024.
- Commercial deploymentNot shownNo sale announced.
What Has Happened Since the Award
The Money
The award was "grant first"; we found no EIC Fund investment. Invest-NL supported the Delft pilot. AquaBattery's share of the SLDBatt subsidy was not disclosed. On 22 April 2024 it closed a €6 million seed round led by EIT InnoEnergy, with InnovationQuarter, Invest-NL, Init Power and business angels, to develop its first standardised battery module and hire staff. Dutch company records were not accessible for this article.
What cannot be checked
The efficiency and cost of AquaBattery's system in the field, its revenue, its investors and when it expects a first commercial installation are not public.
Why Europe Should Care
According to AquaBattery, its salt-water battery avoids critical materials and fire hazards, and it has attracted the EIC, the EU's energy award and Dutch national funding. The question for long-duration storage is cost at scale, which a single pilot cannot yet answer.
What the project promised
A 100% sustainable, infinitely scalable electrical energy storage system.
What the record shows
A cheaper, lighter stack, a 10-hour pilot in Delft and consortium work; no commercial system yet.
The Verdict
Engineering progress, not yet a product
The EIC project made AquaBattery's stack cheaper to build, and a pilot with major utilities followed. But the company is still in pilots and research consortia, and the public record gives no performance data from the field.
AquaBattery has not been asked for comment for this article. It is based entirely on company statements and EU project data, linked throughout.
