Ore Energy is building an iron-air battery for the part of the electricity system that lithium-ion batteries do not serve well: renewable shortfalls lasting several days. The Netherlands-based TU Delft spinout emerged in 2024 with a €10 million seed round and a target of roughly 100 hours of storage. Since then, it has announced grid-connected systems in Delft and a 100-hour pilot at EDF R&D in France.
Those milestones show progress beyond laboratory research. They do not yet establish commercial-scale cost, efficiency, durability, factory output or bankable utility contracts—the measures that will determine whether Ore Energy becomes infrastructure or remains a promising demonstration.
Why four-day storage matters
Most lithium-ion projects are designed for fast response, frequency regulation, solar shifting and commonly around four hours of discharge. That is valuable for daily peaks, but a renewable-heavy grid can also experience several consecutive days of weak wind and sunlight.
Multi-day storage could reduce fossil-fuel backup, renewable curtailment and the need to overbuild generation. The relevant question is not simply whether a battery can discharge for 100 hours. Utilities must compare delivered energy cost, round-trip efficiency, land, maintenance, degradation, response time and the revenues available from capacity, resilience, congestion relief and energy shifting.
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A four-hour lithium-ion system may be better for frequent cycling and rapid balancing. An iron-air system is intended for less frequent, prolonged energy deficits.
What Ore Energy announced in 2024
TechCrunch reported on May 22, 2024 that Ore Energy had emerged from stealth with €10 million in seed funding from Positron Ventures and other investors. The company grew out of research at TU Delft and said it was working with utilities, targeting approximately 100 hours of storage and planning a megawatt-scale factory. Its longer-term ambition was gigawatt-scale production by the end of the decade, focused on the European market.
These were company plans, not evidence of an operating commercial factory or deployed utility fleet. The original announcement is documented by TechCrunch.
How an iron-air battery works
The “rust battery” description is shorthand for a controlled electrochemical system:
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- Discharge: metallic iron is oxidized—effectively rusting—and the reaction produces electricity.
- Charge: electricity reverses the reaction, reducing the iron toward its metallic form.
- Air breathing: oxygen comes from ambient air rather than being stored entirely inside the cell.
- System operation: electrodes, electrolyte, air-management equipment, controls and power electronics turn the cell reaction into a containerized grid asset.
Ore Energy describes the core inputs as iron, water and air. That does not mean the system has no engineered materials or balance-of-plant requirements. Pumps, membranes, electrodes, controls and grid equipment still affect cost, reliability and maintenance. The company’s chemistry description appears in the original TechCrunch report and the European Commission’s F-AIR BAT record.
What has actually been demonstrated
| Date | Milestone | What it establishes—and what it does not |
|---|---|---|
| May 22, 2024 | Stealth launch and €10 million seed round | Funding, origin and commercial ambition; no disclosed commercial deployment. |
| July 2025 | First grid-connected iron-air system in Delft, according to Ore Energy | Grid connection and a company-stated capability of up to 100 hours; not proof of utility-scale economics. |
| August–November 2025 | EDF R&D pilot operating period, according to the company’s later announcement | Operational data gathered under real-world grid conditions; exact power and energy ratings were not disclosed in the cited materials. |
| February 10, 2026 | Completion of a 100-hour grid-connected pilot at EDF R&D’s Les Renardières laboratory in France | A technical pilot demonstrating multi-day operation and grid integration, not a full commercial utility project. |
| Through November 30, 2026 | Scheduled end of the EU F-AIR BAT project | Development timetable, not a guarantee that all cost or durability targets will be met. |
Ore Energy’s announcements describe the Delft connection here and the EDF pilot here.
What “100 hours” means
Hours describe the relationship between a system’s energy and power ratings. Power is measured in kilowatts or megawatts; energy is measured in kilowatt-hours or megawatt-hours. A 1 MW system delivering continuously for 100 hours would contain about 100 MWh of usable energy, assuming the stated output is continuous and the rating is comparable.
Ore Energy’s public materials cited here do not disclose enough information to calculate the exact size of each pilot or to conclude that every system can deliver maximum rated output for 100 hours. A credible project specification must state usable energy, output power, operating conditions and efficiency together.
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Why utilities may care
- Renewable curtailment: store surplus wind or solar instead of switching it off.
- Fossil-backup replacement: cover extended renewable deficits without relying solely on gas generation.
- Grid congestion: charge when transmission is available and discharge during constrained periods.
- Resilience: provide energy through prolonged disruptions, subject to interconnection and operating limits.
- Supply-chain positioning: use abundant iron rather than lithium, cobalt or nickel-rich battery materials.
These are potential applications, not automatic revenue streams. A developer must identify which combination of capacity payments, energy-market spreads, ancillary services, congestion contracts or resilience payments will support the project.
Proposed advantages—and the claims that need testing
Ore Energy and the F-AIR BAT project describe iron-air storage as modular, containerized, recyclable, free of critical raw materials and potentially safer because its aqueous electrolyte is nonflammable. The project record also describes a goal of being approximately 10 times more cost-effective than lithium-ion.
Those statements should be read as company claims or project objectives, not settled market facts. “10 times cheaper” is meaningful only when the denominator is specified—cell materials, installed cost per kWh, levelized cost of storage or another measure. Nonflammable electrolyte does not eliminate risks from electrical faults, corrosion, leaks, pressure, pumps or grid-side equipment. Abundant iron also does not remove supply-chain exposure for membranes, power electronics, controls and factory equipment.
The technical and commercial trade-offs
Efficiency and charging speed
Iron-air may sacrifice round-trip efficiency relative to lithium-ion, although Ore Energy has not published an efficiency figure in the sources cited here. A system optimized for four-day energy delivery may also be less suited to very fast frequency services.
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Degradation and maintenance
Repeated oxidation and reduction can create electrode, material and electrolyte-management challenges. Investors and utilities need cycle-life data, calendar-life data, capacity fade, stack-replacement intervals and maintenance requirements under changing temperature and humidity.
Power-to-energy economics
Long-duration systems can make energy capacity relatively inexpensive while still requiring substantial power electronics, air handling and site equipment. Containerization does not remove land, permitting, water, interconnection or safety-review requirements.
Manufacturing and finance
A pilot can demonstrate a working stack without proving consistent factory yields, warranties, supply contracts or project-finance acceptance. Ore Energy’s proposed megawatt-scale factory and later gigawatt ambition remain plans unless construction, capacity and production data are independently established.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Ore Energy versus Form Energy
Form Energy is the closest high-profile comparison because it also targets roughly 100-hour iron-air storage. Form has a U.S.-focused manufacturing and project-development profile, including plans for a large factory in West Virginia discussed in the 2024 coverage. Ore Energy is a European company spun out of TU Delft and is positioning itself around European grids and supply chains.
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“Iron-air” is a broad technology category, not a standardized product. Cell architecture, electrolyte, electrode design, operating conditions and manufacturing methods can differ substantially, so the two companies should not be assumed to have identical performance or economics. The comparison is discussed in TechCrunch’s original report.
How it compares with other long-duration options
| Technology | Potential fit | Key question for a buyer |
|---|---|---|
| Lithium-ion | Fast response, daily cycling and many four-hour projects | Does higher efficiency and power capability outweigh shorter duration or mineral exposure? |
| Iron-air | Infrequent, multi-day renewable deficits | Can the system prove efficiency, durability and low delivered cost at scale? |
| Flow batteries | Stationary storage where independent power and energy sizing is valuable | How do electrolyte cost, footprint, efficiency and lifetime compare at the project duration? |
| Pumped hydro | Large, long-lived storage where geography permits | Are suitable sites, permits, transmission and construction timelines available? |
| Compressed air and thermal storage | Long-duration applications with site-specific infrastructure | What are the conversion efficiency, geological or thermal requirements and financing risks? |
| Hydrogen | Potentially very long-duration or cross-sector energy storage | Can the lower round-trip efficiency be justified by fuel, industrial or seasonal value? |
What the European funding shows
The European Commission’s F-AIR BAT record names Ore Energy as coordinator under Horizon Europe’s EIC Accelerator framework. It lists an EU contribution of €2,499,817 and a project period from December 1, 2024, through November 30, 2026. Stated objectives include more than 100 hours of storage, modular containerized deployment and lower cost than lithium-ion.
Public funding is evidence of institutional backing and development activity. It is not independent confirmation that commercial cost, efficiency or durability targets have been achieved. The project record is available at CORDIS, with reporting information at the project reporting page.
The numbers a serious buyer still needs
- Usable energy and continuous power at the claimed 100-hour duration.
- Round-trip efficiency under full operating conditions.
- Capacity fade after 100, 500 and 1,000 cycles, plus calendar aging.
- Availability, response time and performance across temperature and humidity ranges.
- Capital cost per kW and kWh, operating cost and levelized cost of storage.
- Stack, electrode and balance-of-plant lifetimes and replacement costs.
- Factory location, validated production capacity, yields and quality controls.
- Signed utility contracts, warranty terms, insurance acceptance and independent validation.
- Land, water, permitting, safety and grid-interconnection requirements.
- The revenue stack that pays for a multi-day asset that may cycle infrequently.
What this means for infrastructure investors
Ore Energy has crossed an important threshold: its story now includes grid-connected demonstrations rather than only a stealth launch and laboratory-derived plans. The Delft and EDF milestones are relevant evidence of integration and multi-day operation.
The investment case remains conditional. The decisive test is whether Ore Energy can manufacture durable systems at predictable cost, achieve acceptable efficiency and availability, and secure utility contracts that value four-day reliability. Until those data are public, the company is best viewed as a promising European contender—not a proven replacement for lithium-ion or a commercially bankable fleet.
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