CLEAN CIRCLES
Metals as carriers of renewable energy in a climate-neutral circular economy

In a unique research approach, iron and its oxides are to be utilised in a cycle as a carbon-free chemical energy source for renewable energy (see figure on the right). Renewable energy is used to reduce iron oxides via a thermochemical or electrochemical process (storage, reduction). Elemental iron can be oxidised locally and separately in time to release thermal energy for electricity generation (release, oxidation). In this way, large quantities of renewable energy can be stored, transported and made available CO2-free, a previously unsolved central challenge of the energy transition under changing political conditions.

Iron as an energy source has excellent physical and chemical properties in terms of transport, storage and energy utilisation. Wind and sun-rich locations inside and outside Germany can be integrated into a CO2-free circular economy for the cost-effective generation and utilisation of renewable electricity. To realise this environmentally friendly solution, the close and complex coupling of engineering, natural, political and economic science issues must be taken into account.

For the reduction and oxidation of iron (oxide), chemical (heterogeneous) reactions and their coupling to transport processes for isolated processes and individual particles must first be understood. Reaction rate-determining phenomena are the heat and mass transfer between particles and the surrounding gas phase as well as the kinetics of the heterogeneous particle surface reaction. These processes are strongly influenced by the ambient conditions (temperature, composition of the gas atmosphere) and the particle properties (particle size, phase, porosity, etc.). Accordingly, a spatially and temporally resolved experimental and numerical analysis of the oxidation and reduction phenomena is required to improve the fundamental understanding.

Further information can be found on the website of the cluster project.