Renewable Energy Storage by Reduction of Iron Oxides

Research Area 1 focuses on the reduction of iron oxide in order to store electric energy obtained from renewable sources. Reduction is investigated in two different approaches: electrochemical and thermochemical reduction.

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Electrochemical reduction

The electrochemical reduction of iron oxides dissolved in ionic liquids is investigated regarding the reaction kinetics and thermodynamics in half-cells. Phase transitions during dissolving iron and its reductive separation are studied in full cells and a Taylor-Couette test bench. Results are used to develop reactor concepts.

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Thermochemical reduction

The sequence of investigations of thermal reduction processes ranges from heterogeneous reaction kinetics to flow reactors, in which chemical reactions couple with physical transport processes, to fluidized beds.


  • Define process conditions and range of parameter values
  • Setup of a rough kinetic and thermodynamic database from parameter studies
  • Setup of a detailed kinetic and thermodynamic database from parameter studies
  • Analyze coupled transport and thermodynamic reduction processes
  • Complete all steps along the process chain for the thermochemical and electrochemical reduction

Research area coordination

  Name Contact
Prof. Dr. Ulrike Kramm
+49 6151 16-20356
Prof. Dr. Olaf Deutschmann
+49 721 608-43064

Projects in research area 1

Experimental investigation of particle clouds

Experimental investigation of iron and iron oxide particle clouds during thermo-chemical oxidation and reduction (B. Böhm)

Kinetic model

Development of a kinetic model based on experimental investigations of the thermochemical reduction/oxidation of iron oxide/iron (O. Deutschmann)

Fluidized bed

Thermo-chemical reduction/oxidation in fluidized beds (B. Epple)

Dissolution and electrochemistry

Dissolution and electrochemistry of iron oxides in ionic liquids and deep eutectic solvents (B. Etzold)

Laser-induced plasma spectroscopy (LIBS)

None-intrusive, time-resolved diagnostics of iron based micro particles undergoing thermo-chemical reduction or oxidation (D. Geyer)

Hard X-ray studies

In situ and operando hard X-ray studies on iron and iron oxide microparticles undergoing reduction or oxidation (Grunwaldt)

Dissolution and motion dynamics

Dissolution and motion dynamics of metallic microparticles in ionic shear flows (J. Hussong)

Mössbauer spectroscopy

Influence of oxidation and reduction conditions on iron signatures as followed by Mössbauer spectroscopy (U. Kramm)

Structure-property relationships (X-Ray Scattering)

Structure-property relationships of iron particles and its oxides (H. Nirschl)

Chemomechanically coupled phase-field model

Phase-field modeling of phase transformation, intra-particle diffusion, microstructure evolution (nm to μm) of iron oxide (D. Raabe)

Kinetic model (CFD simulations)

Kinetic model development for iron particle thermo-chemical reduction/oxidation and investigations of dust firing in CFD simulations (U. Riedel)

Detailed single particle model

Modeling of the reaction-transport coupling for single, iron-based microparticles undergoing thermo-chemical reduction or oxidation (A. Scholtissek)

Density functional theory calculations

Investigations of the reduction of iron oxides using density functional theory calculations (F. Studt)