Europe’s push to decarbonise its energy systems has spotlighted the urgent need for grid stability, supply security, and strategic autonomy. As renewables gain traction, the infrastructure must evolve to balance intermittent generation and withstand external shocks. Dutch company Elestor is stepping into this gap with its hydrogen-iron flow battery, a technology designed for large-scale resilience.
Jacopo Tosoni, Head of Policy at the European Association for Storage of Energy (EASE), underscores the importance of efficient energy storage systems. “They keep prices low by integrating renewables, ensuring cheap electricity, while preventing curtailment and reducing grid congestion,” he says. Elestor’s technology is not just a cleverly engineered solution; it’s a strategic move to equip power systems with scalable, safe, affordable, and geopolitically independent storage.
Today’s grids are under pressure. As solar and wind energy grow, the need for long-duration energy storage becomes critical. Short-term battery solutions like lithium-ion, LFP, or sodium-ion systems fall short during extended periods of low generation, known as “dunkelflaute.” EASE estimates that by 2025 or 2026, battery energy storage systems will overtake pumped hydro in total installed capacity. Elestor’s hydrogen-iron flow battery offers a large-scale, long-duration, and affordable solution. It enables eight to 150 hours of electricity storage with a modular and scalable design. Power and capacity are decoupled, allowing users to scale energy storage by adding liquid electrolyte, a low-cost component, without duplicating power infrastructure.
CEO Hylke van Bennekom explains, “With our design, you can build energy resilience into the grid without overspending. You just scale the part that stores energy.” This approach stabilises renewable energy supply over multiple days, reducing or eliminating dependency on fossil fuel reserves and imported balancing power. It supports energy sovereignty at national and continental levels, democratising the energy system and strengthening democracies.
Technology readiness is not enough for widespread adoption. Solutions must gain public trust, meet regulatory standards, and be operationally safe. Elestor’s hydrogen-iron technology excels here. Iron is abundant, safe to store, and handle. Unlike other redox chemistries, Elestor’s iron-based electrolyte is non-toxic, non-volatile, and requires no hazardous containment. This eliminates the need for ‘forever plastics’ and simplifies permitting processes.
Joep Lauret, Project and Compliance Manager at Elestor, says, “Energy security isn’t just about megawatts and market structures. It’s also about social licence, regulatory clarity and practical deployment. Our hydrogen-iron chemistry meets or exceeds all these requirements.” The system aligns with EU Battery Regulation (2023/1542) and other major safety directives. Elestor collaborates closely with national regulators, local fire brigades, and public safety institutions to ensure each deployment enhances grid safety and system reliability.
Elestor’s redox flow battery stores energy in a liquid electrolyte held in external tanks and circulated through an electrochemical cell. Unlike conventional batteries, flow batteries decouple energy and power, allowing energy capacity and power output to be scaled independently. This architecture suits large-scale stationary storage applications, offering long cycle life, excellent safety, quick response times, and minimal degradation over time, leading to lower total cost of ownership in long-duration energy storage.
Elestor’s hydrogen-iron flow battery uses hydrogen gas and an iron sulphate liquid as active reactants, enabling highly efficient and cost-effective energy storage. Hydrogen’s high energy density, fast reaction kinetics, and flexibility in storage methodologies, along with iron sulphate’s low cost and global availability, make this technology strategically important. It reduces vulnerability to geopolitical leverage over rare or regionally concentrated materials, contributing to the European Commission’s goals of strategic autonomy in energy technologies.
Elestor is not standing still. After completing pilot installations, the company will deploy its first industrial-scale hydrogen-iron battery system this year. With a maximum power output of 500 kilowatts and a storage capacity of up to three megawatt-hours, this project demonstrates the system’s readiness for commercial use. Larger systems will follow, aiming to introduce standardised modules to the market by 2027 or 2028. These installations prove the technical feasibility of integrating long-duration storage into real energy systems, whether coupled with renewables, stabilising grids, or supporting industrial decarbonisation.
Van Bennekom states, “We are not building lab prototypes. We are deploying assets that will keep critical infrastructure running independently, even when the sun isn’t shining and the wind isn’t blowing. This is energy resilience, in practice.”
Elestor’s hydrogen-iron flow battery is more than a technological innovation. It’s a policy-aligned, safety-verified, and economically rational building block for Europe’s future power system