Geyser Batteries and the EIC Accelerator: Water-Based Grid Buffers

Renewables are taking stability out of the grid, Geyser Batteries argues on its website, and the problem sits in the range from milliseconds to minutes, not hours. Geyser Batteries, a Finnish company registered in 2018, builds batteries for that gap with water as the electrolyte solvent and, it says, ordinary carbon, zinc and salts in the cells, with no lithium, cobalt or nickel. The company's pitch is a component that behaves more like a supercapacitor than a storage battery: fast to charge and discharge, many times over, without the fire risk of lithium-ion.

The EIC Accelerator selected the project, GEYSER, for blended finance at its March 2025 cut-off. CORDIS records a grant agreement signed on 25 January 2026 for €2,437,812, running from 1 December 2025 to 30 November 2027. Eleven months into the grant period, the company has published performance claims and named its test partners, but no test report and no named customer.

A battery that wants to be a supercapacitor

Geyser's website says lithium-ion cells and supercapacitors rely on flammable organic solvents, and that its own cells use water instead, have no free electrolyte and no metal electrodes, and stack directly on one another in a bipolar design with no wires, connectors or individual casings between cells. It claims a response time under 10 milliseconds and more than 100,000 cycles, and says a patent family covering more than 50 countries protects the chemistry. The CORDIS objective describes the same thing in its own terms: aqueous, high-power, highly durable batteries made from "common inorganic salts and carbon powders" without critical raw materials or toxic solvents, for "fast energy storage" that levels mismatches between generation and demand "at sub-second-to-minutes intervals".

Geyser does not position the product for shifting solar power into the evening: its website says it is built "for applications that demand rapid charge and discharge, not long-duration storage". The applications its website lists are narrow and technical: the energy buffer inside an E-STATCOM, where it says its cells replace supercapacitors; grid-forming inverters; hydropower plants that must meet faster grid-service rules; and electrolysers that need smoothed input. Business Finland, in a case study dated 12 February 2026, quotes Shigaev saying the product "is designed specifically for rapid power balancing", a range in which, the case says, the company considers lithium-ion too slow and expensive.

The cycle-life claim has moved over the years. In May 2021 the company told IWR its batteries delivered "over one million fast charge cycles" even at extremely low temperatures. The Business Finland case of 2026 says hundreds of thousands, and the current website says more than 100,000. None of the three figures is tied to a published test protocol.

What the EIC is paying for

The selection was announced in July 2025. Mikkeli Development Miksei, the city's business agency, wrote on 4 July 2025 that Geyser was one of two Finnish companies selected in the round, and that the award still depended on a grant agreement with the European Commission and an investment agreement with the EIC Fund. BeBeez reported the same conditions on 1 August 2025, and neither source gave an amount. The grant agreement was signed; whether the EIC Fund investment has been completed is not public, and no amount for it has been announced.

According to Geyser's website, the 24-month project takes the technology from technology readiness level 5 to 6 up to level 8, covering cellblock development, system integration and validation. The July 2025 announcement put it in plainer words: complete product development, set up a pilot production line and run large-scale trials with customers in Finland and Spain. CORDIS shows no periodic report or deliverable yet; the project started in December 2025.

1. Signed grant agreementDoneSigned 25 January 2026 for €2,437,812, per CORDIS.
2. Independent performance testingClaimedThe company says Fraunhofer IEE and VTT validated its cells; no test report has been published.
3. Pilot production lineNot reportedNo announcement of a running line could be found.
4. Customer trials in Finland and SpainIn preparationPilots described by the company; partners unnamed.
5. TRL 8 by November 2027Too earlyThe project runs for another 13 months.

The cells were already in an EU consortium

The EIC grant is not the company's first EU money. CORDIS lists Geyser Batteries Oy as a participant in AGISTIN, a Horizon Europe project on storage at the grid interface that runs from 1 January 2023 to 31 December 2026, with a net EU contribution to Geyser of €709,629.38 against a total cost of €1,013,756.25. The project's objective names "aqueous electrochemical recuperators" among the storage technologies it tests, alongside irrigation systems and aluminium ion batteries, and the consortium includes Fraunhofer, Shell Global Solutions, the French transmission operator RTE and EPRI Europe as coordinator.

Geyser's website says Fraunhofer IEE completed power-hardware-in-the-loop testing of a Geyser battery module between February and May 2026 under AGISTIN, covering grid-forming fault response, islanded microgrid operation and continuous frequency regulation, and that VTT validated its cellblocks for the Nordic frequency reserves FCR-N and FCR-D. Those results appear only on the company's site: a search of CORDIS and the web on 28 October 2026 found no published report from Fraunhofer, VTT or AGISTIN on the tests.

The Business Finland case describes the first large-scale demonstration as being in Spain, where the battery is integrated into a setup linking a solar plant to a pumped hydro facility, with pilots alongside hydropower plants in Finland and the Nordic countries to follow and all pilots built and completed by 2028.

Agreements without names

The Business Finland case says the first large supply and joint production agreements were signed in Australia, and that the company expects most production over the next ten years to come from 10 to 15 joint ventures or licensed factories worldwide, each with 5 to 10 gigawatts of fast-cycling capacity a year. It does not name the partners. A company profile on battery-tech.net says Geyser signed a conditional supply agreement with Released Energy in 2023 for 85 megawatts in Australia and the United Kingdom. No press release from either company about that agreement could be found, so its terms and its current status could not be verified.

Twelve staff and a negative equity ratio

Geyser raised a €1 million seed round in December 2019 led by Voima Ventures, with Butterfly Ventures and the Ehrnrooth family office, according to Tech.eu, which described the company as based in Vaasa. In May 2021 the company told IWR it had chosen Mikkeli for a pilot plant and research centre, to be operational from mid-2022 with about 30 employees initially, while the headquarters stayed in Helsinki. Miksei says Geyser set up its Mikkeli operations in 2022. No equity round after the EIC award has been announced.

The figures filed with the Finnish register are summarised by the credit agency Asiakastieto. They show an operating loss in each of the five years from 2021 to 2025, from €183,000 in 2024 to €889,000 in 2023, and a revenue figure for one year only: €55,000 in 2024. Staff peaked at 28 in 2022 and has been 12 or 13 since. For 2025 the agency lists an equity ratio of minus 77%, counting subordinated loans as debt.

The Finnish Patent and Registration Office records the company as registered in the trade register, with manufacture of batteries and accumulators as its main line of business and no insolvency, liquidation or other restructuring entry. Its postal and street addresses were changed to Laippatie 4 in Helsinki on 1 April 2026.

The case for Europe

The project's argument is supply-chain resilience: the CORDIS objective says raw materials "bearing no geopolitical risks" enable "a resilient EU-based supply chain", and the company's website says production needs no dry rooms or clean rooms. That matches the purpose of the EU's Critical Raw Materials Act, in force since 23 May 2024, which covers critical raw materials "such as lithium for batteries". CORDIS tags the whole GEYSER contribution as climate action.

The reporting is based on publicly available sources, listed below.