Iron power plants from coal-fired power plants

CORAL: Combustion of Rechargeable Metal Fuels in Fluidized Bed Boilers

The next generation of iron-based energy storage is taking shape: since September 2024, the European research project CORAL has been developing the technical foundations for converting existing coal-fired power plants into CO₂-free iron-based power plants. With a budget of almost €4 million and an international consortium of leading research institutions and industry partners, CORAL is bringing the scientific findings developed at Clean Circles directly into industrial application.

From basic research to market maturity

CORAL bridges the gap between the cutting-edge research on metal-based energy carriers developed at Clean Circles and its large-scale implementation. While Clean Circles researched the scientific principles of iron-based energy cycles, CORAL focuses on practical implementation: retrofitting existing coal-fired power plants with fluidized bed combustion for burning iron powder.

Top-level European research with a Darmstadt core

The 3.5-year project (September 2024 to February 2028) is coordinated by Chalmers University in Sweden and brings together leading European research institutions and industry partners. TU Darmstadt contributes its expertise in CFD simulation and experimental characterization of iron-based combustion processes, developed through Clean Circles and A-STEAM. Led by M.Sc. Yannik Lichtmannegger, the Darmstadt team is developing numerical models for optimizing boiler efficiency and particle handling.

International Partnership for Energy Transition:

TU Darmstadt (Germany): Coordination, CFD simulation, and combustion modeling
Chalmers University (Sweden): Fluidized bed technology
Fortum Corporation (Finland): Energy supply and market introduction
Politecnico di Milano (Italy)
Pometon (Italy): Iron powder production and recycling
Lappeenranta-Lahti University (Finland): System integration and evaluation
Spanish National Research Council (Spain): Process optimization
Sumitomo SHI FW (Finland): Plant engineering and industrialization
VGBE (Germany)

Technological innovation through retrofitting

The core concept of CORAL is based on an elegant technical solution: existing coal-fired power plants with fluidized bed combustion can be converted for the combustion of iron powder with relatively minor modifications. This not only enables the continued use of existing infrastructure, but also preserves jobs and industrial value creation in traditional energy regions.

The CORAL-process:

Oxidation: Iron powder is burned in the converted fluidized bed combustion system, generating CO₂-free heat for electricity and district heating production.
Separation: The resulting iron oxide is collected through optimized particle separation.
Reduction: Hydrogen-based re-reduction of the iron oxide to metallic iron using renewable energies.
Recycling: The regenerated iron powder is once again available as an energy source.

Scaling up to the megawatt range

CORAL systematically develops and tests retrofit technology on various scales – from laboratory tests to pilot plants with 1 MW thermal output. This step-by-step scaling ensures technical feasibility and paves the way for commercial applications on a power plant scale.

Comprehensive modeling using CFD (computational fluid dynamics) simulations enables precise prediction of flow behavior, heat transfer, and particle distribution in complex fluidized bed systems. These digital twins accelerate development and minimize risks during later implementation.

Outlook: Industrial Transformation

When the project is completed in February 2028, CORAL will have laid the technical and economic foundations for the large-scale retrofitting of coal-fired power plants to become CO₂-free iron power plants. The findings pave the way for industrial market introduction and support structural change in European energy regions.

CORAL proves that the transition to a climate-neutral energy supply does not necessarily mean the demolition of existing infrastructure – but rather enables a renaissance of traditional energy sites through intelligent technologies.