A battery that stores energy for four days using nothing but iron, water, and air just landed $43 million in Series A funding. Netherlands-based Ore Energy announced the raise on 4 August, led by investors Plural and HV Capital, bringing its total funding to over $61 million. The company has also secured what it calls the largest iron-air battery deal in continental Europe so far.
How Iron-Air Batteries Work
The technology is deceptively simple. During charging, electricity reverses iron oxidation (rust). During discharge, the iron rusts again, releasing energy. One of the two reactants, oxygen, is drawn directly from the atmosphere, which means the battery does not need to ship with all its active materials inside.
Ore Energy’s system is built into modular 40-foot shipping containers that can be daisy-chained together for scalability. Each unit can store energy for up to 100 hours, roughly four days. That is a significant step beyond lithium-ion systems, which typically deliver two to four hours of storage. For anyone exploring off-grid or energy-independent setups, the prospect of multi-day storage from cheap, abundant materials is worth paying attention to.
The trade-off is size and efficiency. Iron-air batteries are bulkier and less energy-dense than lithium-ion alternatives. They are not a replacement for the battery in your phone or your car. But for stationary storage, where space is less constrained and duration matters more than density, the economics are compelling.
The European Deal
Alongside the funding, Ore Energy announced a 1 GWh supply agreement with Budget Thuis, a Dutch energy supplier. The first phase covers 400 MWh of capacity, with delivery targeted for 2028. The purpose is straightforward: store excess wind power during periods of high generation and release it when electricity prices spike and renewable output drops.
This is the kind of flexibility that Europe’s grid increasingly needs. As solar and wind capacity grows (the EU is on track for renewables to supply 63% of electricity by 2030, according to IEA projections), the mismatch between when power is generated and when it is consumed gets worse. Short-duration batteries help smooth daily peaks. Long-duration systems like Ore Energy’s can bridge multi-day gaps during calm, cloudy weather.
Proven Under Real Conditions
Ore Energy is not operating purely on promise. The company ran a pilot with EDF in France between August and November 2025 that demonstrated four days of continuous storage under real grid conditions. It also has a grid-connected installation in Delft, Netherlands, where the technology was originally developed at TU Delft.
The Series A funding will go toward establishing Ore Energy’s first manufacturing facility, with the target of reaching gigawatt-hour scale production by 2028. The raw materials (iron is one of the most abundant elements on Earth) and the avoidance of critical minerals like lithium and cobalt give the company a supply chain advantage, particularly for European production where reducing dependence on imported battery materials is a strategic priority.
What This Means for Home Energy Storage
Iron-air batteries are not coming to your garage any time soon. The current systems are designed for grid-scale and commercial applications. But the ripple effects matter. More long-duration storage on the grid means more stable electricity prices, fewer blackout risks during extended low-wind periods, and a stronger case for going all-electric at home.
If the technology scales as Ore Energy projects, it could also open up possibilities for community energy schemes and microgrids, where multi-day resilience without diesel backup generators has been a persistent gap. For now, this is one to watch rather than one to buy.
Photo by Sungrow EMEA via Unsplash.
