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Science YouTuber Jacob Beautemps, known for his channel “Breaking Lab”, visited TU Darmstadt, specifically the Reactive Flows and Diagnostics (RSM) and Energy Systems and Energy Technology (EST) departments, to learn more about the interdisciplinary research project Clean Circles. The project addresses one of the key challenges of the energy transition: how can renewable energy be stored in a way that is long-term, climate-neutral, and responsive to demand?

At the heart of the project lies iron as a recyclable energy carrier. Energy can be stored in iron via two different processes: either directly through electrochemical reduction or indirectly through thermochemical reduction using green hydrogen. When the reduced iron is later oxidized at the point of use, the stored chemical energy is released at high temperatures and can be converted back into electricity in controllable thermal power plants.

Iron is particularly attractive because it oxidizes without emitting CO₂, making it a fully carbon-free energy carrier. It can also be stored for very long periods without significant energy losses—an important advantage over many conventional storage technologies. The high temperatures reached during oxidation enable a high power density, which in turn supports compact and easily controllable power plant concepts. Overall, iron offers a promising pathway to ensure a secure energy supply, even when wind and solar energy are not sufficiently available.

Read more about metals as energy carrier here!