“With iron as an energy carrier, climate neutrality can become a reality in Germany by 2045,” explained Professor Andreas Dreizler, spokesperson of the Clean Circles project. “Innovative long-term storage is essential for the success of the energy transition and decarbonisation.”

During his visit, Minister Mansoori watched how iron is burnt in the form of small particles. The stored energy is released as high-temperature heat – without any harmful emissions. This means that coal can be replaced by iron in existing power plants, enabling CO₂-free heat and power generation. Another application is in industrial processes that require high-temperature heat that is often difficult to electrify.

Minister Mansoori was very impressed by the demonstration of the storage technology: “The research at TU Darmstadt shows impressively how innovative approaches to the energy transformation are being investigated at a high level. Only such interdisciplinary projects at the boundary between basic research and practical implementation can answer the question of what potential iron has as a CO₂-free energy source to make a decisive contribution to the energy transition. If this is confirmed, it would be a major step for Hesse and could serve as a model for the whole of Germany.” [original quote in German ]

Emission-free cycle

One particular advantage of iron powder as an energy storage medium is its ability to be recycled. It can repeatedly absorb renewable energy where there is wind and sunshine and release this energy at different locations. This enables flexible and efficient utilisation of renewable energy sources. Dreizler explained: “Unlike other fuels, the product here is only solid iron oxide, which can be recycled back into pure iron using renewable energy – the storage is thus recharged.”

Early career researchers play an important role in Clean Circles. In conversation with Minister Mansoori, student and Direct Track scholarship holder İrem Alp expressed her enthusiasm: “It's incredibly motivating to make a contribution to an environmentally friendly and sustainable energy supply.”

Pioneering research on the way to application

Thanks to funding from the Hessian Ministry of Science, the researchers at Clean Circles were quickly able to establish themselves at the forefront of international basic research into metals as energy sources. Their next step is industrial implementation in the form of a demonstrator to show the industrial feasibility of the concept.

The President of TU Darmstadt, Professor Tanja Brühl, explained: “As a technical university, we combine excellent fundamental research with cooperative application. This is how our pioneering solutions for tomorrow are created. Clean Circles is an outstanding example of how the scientists at our university fulfil this requirement and develop trailblazing contributions for a sustainable energy supply.”