A Dutch startup thinks it has the answer to two of Europe’s biggest energy transition conundrums – long-duration storage batteries that are free from critical minerals and powered by rust. 

In a pilot project in February, Amsterdam-based Ore Energy supplied four days of uninterrupted power to a research facility operated by France’s EDF electricity utility using a battery made of little more than iron pellets, water and air. That followed a grid installation in the Netherlands last year.

“These are the first instances of grid-connected iron-air batteries in Europe,” Yakup Koç, Ore Energy’s chief operating officer, told Climate Home News. “With these deployments, we’ve proven that the technology really works.”

Using abundant, cheap materials that can be sourced locally across Europe, iron-air batteries store and release electricity through a simple, chemical process: rusting and de-rusting.

“Rusting refers to discharging, and de-rusting refers to charging,” Koç said. “When discharging, air is drawn in and reacts with the iron, forming rust and releasing electricity in the process. To recharge, the oxygen is removed, and the rust reverts to iron, ready to go again.”

Energy transition’s “missing link”

Batteries able to store solar and wind power over longer periods of time than conventional lithium-ion batteries are often described as the “missing link” in the energy transition.

Technology such as Ore Energy’s could hold particular appeal for Europe as it strives to reduce its exposure to volatile critical mineral supply chains and boost its production of batteries for power storage and electric vehicles (EVs) instead of relying so heavily on imports from China.

“There are no critical raw materials in our batteries … which means we are truly independent of supply chain issues in that sense,” Koç said.

It also makes them cheaper than established batteries, which mostly use either lithium iron phosphate (LFP) or lithium nickel cobalt manganese oxide (NMC) chemistries.

“Critical raw materials are expensive,” Koç adds. “Because we’re using abundant resources, our cost price can be as much as 10 times lower than lithium.”

Europe sprints for storage capacity

Wind and solar make up the fastest-growing energy sources globally, but bridging inherent supply fluctuations requires batteries capable of storing energy for far longer than currently possible with a typical lithium-ion battery.

Demand for battery energy storage systems has surged and it currently accounts for 15% of global battery demand, according to the International Energy Agency (IEA).

Multi-day storage capabilities will become increasingly important as renewable integration booms, said Zeenat Hameed, principal analyst for energy storage at Wood Mackenzie.

“Under net-zero scenarios, the average duration of newly installed storage assets may need to increase from around 2.5 hours today to roughly 20 hours to manage multi-day variability in wind and solar generation,” she told Climate Home News.

Europe added a record 27.1 GWh of new batteries in 2025, bringing total capacity to 77.3 GWh, according to a recent report by industry group SolarPower Europe, adding that capacity must increase 10-fold by 2030 to meet its needs.

With about 90% of battery-storage applications relying on Chinese lithium batteries, steps to diversify suppliers are also seen as vital to shore up energy security.

Innovation that can help reduce or diversify battery mineral supplies and demand – for example, technologies that do not require critical minerals – could play a key role in shoring up energy security, the IEA says.

Uncomplicated alternative?

This is where iron-air comes in.

Koç said Ore’s system can be configured to store energy anywhere between 24 and 100 hours, and is capable of being reused over a lifespan of as much as 20 years.

Each battery storage unit ships in standard 40-foot containers, a similar size as lithium-ion systems, and can be connected and operational within days of arriving on site.

Ore Energy is not the only company in the race to bring iron-air to the market.

US-based Form Energy, which has also developed an iron-air battery system, has partnered with Xcel Energy on a 10-megawatt (MW) iron-air system in Minnesota at a retiring coal plant. They have also announced plans to provide a 300-MW iron-air system to power a new Google data centre.

Beyond iron-air, a broader range of long-duration energy storage (LDES) technologies is taking shape. US-based Noon Energy is developing a carbon-oxygen battery based on solid-oxide fuel cell technology which it says avoids “scarce metals and minerals” and targets storage durations of 100 hours and above, while E-Zinc’s zinc-air systems are another player in the ultra-long-duration bracket.

Mahika Sri Krishna from the LDES Council, a global organisation focused on accelerating long duration energy storage solutions, told Climate Home News a mix of different technologies would be necessary to support grid reliability as renewables gain ground.

“Medium-duration storage solutions can help manage daily variability in renewable generation, while very long-duration systems may help address less frequent but more challenging reliability events,” said Sri Krishna, a senior manager for research and analysis at the group.

Last longer, scale up faster

Iron-air faces numerous challenges to scale-up and challenge established battery technologies, however, energy experts say.

Demand for multi-day storage is not yet high enough to drive commercialisation, Hameed said, estimating that lithium-ion is expected to retain about 85% of the global storage market through 2034 as economies of scale and manufacturing innovations reduce its costs.

While iron-air’s raw materials are cheap, the overall system cost still needs to prove itself at scale, Hameed added.

At Ore Energy, the next step is moving from single- to multi-container configurations, building what Koç describes as an “energy reservoir” that can be deployed across different use cases.

The scale-up itself, he said, is less the challenge than gaining industry acceptance by building a commercial track record.

“It’s not only about customers seeing the data and knowing it works,” he said. “The whole ecosystem around a new technology has to be brought along.”

When that happens, the technology could have transformative effects on Europe’s energy transition, he said.

“Europe will not decarbonise its power system on renewables alone,” Koç said. “Without long-duration storage, Europe risks replacing dependence on fossil fuels with dependence on overbuilding, curtailment and backup generation.”

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Dutch startup’s rust-powered batteries could help crack Europe’s energy storage gap