Recycling of solid oxide electrolyzer stacks

Sustainable materials and technologies, vol. 45, pp. e01435

Abstract

In recent years, hydrogen has become an increasingly important energy carrier, replacing fossil fuels. In this context, electrolyzers have become a focal point of global research, as they facilitate the production of green hydrogen. Among electrolyzers, solid oxide electrolyzers are one of the most widely researched due to their high efficiency and their variability in terms of fuels and operation as fuel cells. However, due to the use of critical materials in combined with a relatively short operational lifespan, the development of recycling strategies is becoming increasingly crucial if these electrolyzers are to become a sustainable option for green hydrogen production. This study proposes the first comprehensive recycling scheme for solid oxide electrolyzer stacks. Data on the materials used by electrolyzer manufacturers from around the world was compiled and compared. Based on these materials, published recycling approaches from dismantling, mechanical recycling and metallurgy were combined with additional studies to develop a holistic recycling process aimed at recovering critical raw materials. Options for closed-loop and open-loop reuse were considered and existing gaps and challenges were identified. The current status of recycling solid oxide electrolyzer stacks demonstrates that the principle is feasible and that a significant proportion of the materials used can already be separated and recovered. However, existing gaps, such as the separation of the nickel mesh from interconnects and the separation of various oxygen ion conductors, currently result in materials being downcycled or recycled in an open loop.

Authors 14

1. Carlo Kaiser corresponding

   TU Bergakademie Freiberg

   Affiliation as printed

   Institute for Mechanical Process Engineering and Mineral Processing, Technical University Bergakademie Freiberg, Agricolastraße 1, Freiberg 09599, Germany

2. Sohyun Ahn

   Helmholtz-Zentrum Dresden-Rossendorf · Helmholtz Institute Freiberg for Resource Technology

   Affiliation as printed

   Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Chemnitzer Straße 40, Freiberg 09599, Germany

3. Dominik Goes

   Karlsruhe Institute of Technology

   Affiliation as printed

   WBK Institute of Production Science, KIT Karlsruhe Institute of Technology, Kaiserstraße 12, Karlsruhe 76131, Germany

4. Jeraldine Lastam

   Forschungszentrum Jülich

   Affiliation as printed

   Institute of Energy Materials and Devices, Microstructure and Properties of Materials (IMD-1), Forschungszentrum Jülich GmbH, Jülich 52425, Germany

5. Shine‐Od Mongoljiibuu

   TU Bergakademie Freiberg

   Affiliation as printed

   Institute for Mechanical Process Engineering and Mineral Processing, Technical University Bergakademie Freiberg, Agricolastraße 1, Freiberg 09599, Germany

6. Stephan Sarner Aachen Institute of Mineral Engineering (GHI)

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Materials and Devices, Materials Synthesis and Processing (IMD-2), Forschungszentrum Jülich GmbH, Jülich 52425, Germany

   RWTH Aachen University, Institute of Mineral Engineering, Forckenbeckstr. 33, Aachen 52074, Germany

7. Alexander Specht Aachen Institute Chair for Process Metallurgy and Metal Recycling

   RWTH Aachen University

   Affiliation as printed

   Institute and Chair for Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestraße 3, Aachen 52056, Germany

8. Jürgen Fleischer

   Karlsruhe Institute of Technology

   Affiliation as printed

   WBK Institute of Production Science, KIT Karlsruhe Institute of Technology, Kaiserstraße 12, Karlsruhe 76131, Germany

9. Norbert Heribert Menzler Aachen Institute of Mineral Engineering (GHI)

   Forschungszentrum Jülich · RWTH Aachen University

   Affiliation as printed

   Institute of Energy Materials and Devices, Materials Synthesis and Processing (IMD-2), Forschungszentrum Jülich GmbH, Jülich 52425, Germany

   RWTH Aachen University, Institute of Mineral Engineering, Forckenbeckstr. 33, Aachen 52074, Germany

10. Martin Rudolph

    Helmholtz-Zentrum Dresden-Rossendorf · Helmholtz Institute Freiberg for Resource Technology

    Affiliation as printed

    Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology, Chemnitzer Straße 40, Freiberg 09599, Germany

11. Bernd Friedrich Aachen Institute Chair for Process Metallurgy and Metal Recycling

    RWTH Aachen University

    Affiliation as printed

    Institute and Chair for Process Metallurgy and Metal Recycling, RWTH Aachen University, Intzestraße 3, Aachen 52056, Germany

12. Olivier Guillon

    Forschungszentrum Jülich

    Affiliation as printed

    Institute of Energy Materials and Devices, Materials Synthesis and Processing (IMD-2), Forschungszentrum Jülich GmbH, Jülich 52425, Germany

13. Ruth Schwaiger

    Forschungszentrum Jülich

    Affiliation as printed

    Institute of Energy Materials and Devices, Microstructure and Properties of Materials (IMD-1), Forschungszentrum Jülich GmbH, Jülich 52425, Germany

14. Urs Alexander Peuker

    TU Bergakademie Freiberg

    Affiliation as printed

    Institute for Mechanical Process Engineering and Mineral Processing, Technical University Bergakademie Freiberg, Agricolastraße 1, Freiberg 09599, Germany