Development and construction of stationary iron-air long-duration energy storage systems for seasonal storage
Iron Energy AG
Zurich (CH) · Grenzach-Wyhlen (DE)New on Amplifa
About Iron Energy
Iron Energy AG is an ETH spin-off from Zurich that develops and builds large-scale, stationary long-duration energy storage systems based on iron-air batteries. The technology stores electrical energy in the form of metallic iron: in a reversible solid oxide fuel cell (rSOFC), hydrogen is first produced, which reduces iron oxide to metallic iron at around 500 °C; during discharge, the process is reversed exothermically and hydrogen is fed back into the rSOFC to generate electricity. The storage systems operate at ambient pressure in the solid state, achieve power-to-power efficiencies of up to 60% and release the residual energy as high-temperature heat (500 °C). The systems are customised according to customer profiles and target renewable energy projects, waste incineration plants, wastewater treatment plants, critical infrastructure, the balancing power market and energy communities. In addition to its headquarters in Zurich, the company operates an R&D site in Grenzach-Wyhlen (Germany); in 2023, a 10-MWh pilot plant was commissioned on the ETH Hönggerberg campus.
- Site
- Zurich
- Processes
- Development and construction of large-scale, stationary long-duration energy storage systems, Seasonal Energy Storage, Heat supply as a by-product (High-Temperature Heat 500°C), Customised storage systems according to customer profile
- Materials
- Iron oxide (FeOx), Metallic iron (Fe), Stainless steel (storage tanks), Iron oxide (Iron Oxide), Metallic iron (Iron), Hydrogen (process gas)
- Certificates
- CE certification (demonstration plant)
- Founded
- ETH Spin-o
- Industries
- Renewable energy projects, Waste incineration plants, Wastewater treatment plants, Critical infrastructure, Balancing power market / Reserve Market, Energy communities
- 01
Engineering & design of the storage system
- 02
Manufacturing of the stainless-steel storage tanks
- 03
Integration of the rSOFC electrolysis/fuel cell
- 04
Commissioning & cyclic test operation
- 05
Operation and heat/power supply at the customer
Storage Materials & Processes
Iron oxide (Iron Oxide)
Storage material that is reduced to metallic iron with hydrogen during charging at approx. 500 °C and is reused in the tank.
Metallic iron (Iron)
Solid, safely storable energy carrier that is oxidised back to iron oxide during discharge, releasing hydrogen.
Stainless steel (storage tanks)
Material of the storage tanks for holding the iron-oxide-containing storage medium at high temperature.
Hydrogen (process gas)
Reaction and working medium between the rSOFC and the iron storage unit in a closed loop.
Sites
Zurich
CHHeadquarters, R&D, laboratory (Gen2 prototype) as well as pilot plant on the ETH Hönggerberg campus
- Materials
- Iron oxide, metallic iron, stainless steel
- Pilot reactor 10 MWh (3 stainless-steel storage tanks)
- Gen2 laboratory prototype (210 l, 250 kg iron ore, approx. 250 kWh)
Grenzach-Wyhlen
DEResearch & development; site of the CE-certified demonstrator
- Materials
- Iron oxide, metallic iron, stainless steel
- CE-certified demonstrator 20 MWh / 200 kW (650 kg H2 storage, commissioning planned for late summer 2026)
Projects & Systems
Inside the production
Industries
3 Anlagen & Maschinen
| Machine | Manufacturer / model | Quantity | Working area | Year built | Site |
|---|---|---|---|---|---|
| Pilot reactor (seasonal energy storage plant, 3 stainless-steel storage tanks, 10 MWh) | Iron Energy / ETH Zurich Functional Materials Laboratory Pilot Plant ETH Hönggerberg | 1 | 10 MWh storage capacity | 2023 | Zurich (Hönggerberg), Switzerland |
| Laboratory reactor (Gen2 prototype, 210 l internal volume, 250 kg iron ore, approx. 250 kWh storage | Functional Materials Laboratory (Prof. Dr. W. Stark), ETH Zurich Gen2 prototype | 1 | 210 l internal volume | – | Zurich, Switzerland |
| CE-certified demonstrator (energy storage system, 20 MWh / 200 kW, H2 storage capacity 650 kg) | Iron Energy | 1 | 20 MWh / 200 kW, 650 kg hydrogen storage | 2026 (gepl | Grenzach-Wyhlen, Germany |
Additional services
Reference customers
Quality & Certification
The 20-MWh/200-kW demonstration plant is CE-certified and is intended to complete 50 full operating cycles under industrial conditions within 1.5 years (funded by Innosuisse, TRL 6 to TRL 8).
| Evidence | Grenzach-Wyhlen |
|---|---|
| CE certification (demonstration plant) |
History
- 2023
Founder Dr. S. Heiniger commissioned a 10-MWh pilot plant with three stainless-steel storage tanks on the Hönggerberg campus as part of his dissertation at the Functional Materials Laboratory of ETH Zurich.
- 2026
Planned start of operation of the CE-certified 20-MWh/200-kW demonstrator (650 kg H2 storage, 50 cycles in 1.5 years, funded by Innosuisse) in Grenzach-Wyhlen; start of projects with NTS Workspace AG (Bern) and GEWOBAG.
- 2029
Planned commissioning of the Bern project (NTS Workspace AG, 3'000 MWh / 6 MW) – by capacity the largest battery in Switzerland.
- 2031
Planned commissioning of the GEWOBAG project (500 MWh seasonal storage, Urdorf/Zurich, supplying more than 200 apartments).