Green metals as recyclable carriers of renewable energy - From global opportunities to combustion physics

Speaker: Prof. Christian Hasse

Host: Prof. Christof Schulz

Abstract

The transition from fossil fuels to renewable energy hinges on scalable ways to store and transport energy, because most renewable sources are intermittent and their production is often geographically decoupled from demand. Recent assessments put the seasonal storage need at more than 1000 TWh for Europe alone. At these scales, chemical energy carriers, i.e. fuels, are a practical option: besides green hydrogen, ammonia, and e-fuels, metals such as iron and aluminum are compelling as carbon-free, high-energy-density carriers with low toxicity, easy handling, abundant supply, and, in principle, indefinite recyclability.

The talk conveys two key messages, mirrored in its two parts.

First, metal fuels are a promising carrier of renewable energy for a net-zero carbon society. Iron is introduced as a recyclable carrier: reducing iron oxide stores renewable electricity from wind, hydro, and solar, and subsequent combustion releases it as high-temperature process heat or power, leaving solid iron oxide that is collected and recycled. A key opportunity is retrofitting existing infrastructure, illustrated by a thermodynamic system analysis of a coal-fired power plant repurposed for iron powder, followed by a techno-economic analysis with different partner countries for reduction and oxidation, comparing hydrogen and iron by round-trip efficiency and levelized cost of electricity.

Second, while decades of research on solid carbonaceous fuels provide an excellent starting point, the physics of metal combustion is fundamentally different, fascinating, and still largely unexplored. Building up from the single microparticle, the talk synthesizes generic laminar metal flames, emphasizing particle-particle-fluid interactions, reaction-zone structure, and propagation modes, before turning to turbulent metal combustion and the key scientific challenges ahead.

Short Biography

Christian Hasse is a Full Professor at Technical University of Darmstadt (Germany) and has been with the Department of Mechanical Engineering since 2017. He directs the Institute for Simulation of Reactive Thermo-Fluid Systems, leading a team of more than 30 PhD candidates and postdoctoral researchers. He earned his PhD in Mechanical Engineering from RWTH Aachen University in 2004 and worked in engine R&D at BMW Group in Munich before moving to academia. In 2010, he was appointed Professor of Numerical Thermo-Fluid Dynamics at TU Bergakademie Freiberg. His research advances the fundamental understanding of reactive thermo-fluid phenomena through high-fidelity modeling and simulation, with a focus on emerging renewable energy carriers such as hydrogen, ammonia, e-fuels, sustainable aviation fuels, and metals. He considers engineering-based fundamental research a vital bridge between scientific curiosity and real-world impact. He has authored more than 300 peer-reviewed publications and delivered over 25 invited plenary and keynote lectures. Committed to mentoring early-career researchers, he has supported many who later received prestigious international awards and faculty appointments.

He is a Fellow of The Combustion Institute and the Royal Aeronautical Society (UK), serves on the Boards of Directors of both the International and German Sections of The Combustion Institute, and received an ERC Advanced Grant (2024) for A-STEAM – Aluminum Steam Combustion for Clean Energy. He is the recipient of the 2026 Gottfried Wilhelm Leibniz Prize of the German Research Foundation (DFG, Deutsche Forschungsgemeinschaft).

Registration: https://plan.events.mpg.de/event/828/

The colloquia series is organized by of the International Max Planck Research School on Sustainable Metallurgy (IMPRS SusMet)