Loop reactor for hydrogen production and storage by reacting iron with water


Climate-neutral hydrogen production is one of the keys towards achieving global climate goals. Basically, the water/iron reaction (3 Fe + 4 H2O → Fe3O4 + 4 H2) allows direct production of hydrogen from water, without the use of fossil fuels. Since iron is a widely available and inexpensive element, the reaction route could be a cost-effective and sustainable method for hydrogen production. Moreover, hydrogen can be both produced and stored as needed. Thus, the reaction route holds the potential for a continuous energy supply, which is particularly important for balancing fluctuations in renewable energy production.

Within this project, funded by the KIT Academy for Responsible Research, Teaching, and Innovation (ARRTI), a loop reactor with a tailored Fe matrix of high cycling stability is to be developed, aiming at decentralized, fast, and clean hydrogen production from water vapor by conversion of Fe into Fe3O4.

Chemical looping enables regeneration of reversible complex porous structure (CPS) from Fe3O4 to Fe with excess H2 from renewable sources. Our reactor concept offers the following advantages:

  • Fast hydrogen supply on demand - even without solar and wind power, a major advantage compared to water electrolysis, microbial fermentation and/or solar water splitting.
  • Potential for H2 storage by regeneration of the Fe3O4 CPA matrix. In other technical processes: Storage of H2 complicated due to low volumetric energy density. In addition, hydrogen gas is highly flammable and requires specific storage and handling procedures to ensure safety.
  • Impurity-free H2 production compared to biomass gasification.
Figure 1. Sketch of the loop reactor and the overall reaction.

Applicants and contact persons:

Fabian Hagen und Björn Stelzner