Superconductivity for railway applications: A review

This review explores the application of superconductivity in the railway industry, encompassing both magnetic levitation (maglev) systems and innovations in conventional electrified railways. As the world faces urgent challenges related to climate change, energy efficiency, and the transition to renewable energy, superconductivity offers a promising path forward by enabling loss-less current transport, reducing emissions, and optimizing energy use in rail systems. Superconductivity aligns closely with several United Nations Sustainable Development Goals (SDGs), specifically for SDG 07: Affordable and clean energy, SDG 09: Industry, innovation, and infrastructure, SDG 11: Sustainable cities and communities and SDG 13: Climate action. The review incorporates a bibliometric analysis using the Clarivate Web of Science, identifying 116 scientific articles focused on the intersection of superconductivity and railway technology. The analysis highlights the leading research contributions and top-cited authors, the key institutions driving innovation and the predominant research themes and micro-citation trends. These findings provide valuable insight into the technological landscape, enabling stakeholders to track emerging topics, identify collaboration opportunities, and support strategic planning toward sustainable railway development. The paper also discusses the progress of superconducting materials tailored for large-scale transport applications. High-temperature superconductivity (HTS), operating at liquid nitrogen temperatures, is particularly emphasized due to its potential for loss-free current transport, higher energy efficiency and compact, high-performance components for railway use. These benefits are strongly linked to the global attention focused on climate change, carbon reduction, and the transition to sustainable energy systems. Superconductivity in railway systems is explored in two main research directions, covering both superconducting maglev systems and conventional electrified railways. For maglev systems, the three fundamental levitation principles – Electromagnetic Suspension (EMS), Electrodynamic Suspension (EDS), and HTS-based flux pinning – are outlined. Major international developments and future maglev innovations are discussed, highlighting the next generation of high-speed rail driven by superconductivity-based maglev systems. In the case of conventional, electrified railways, superconducting technologies are increasingly applied to both onboard systems, including transformers, motors, eddy-current brakes and contactless power supplies, and the supporting infrastructure, comprising superconducting feeder cables, energy storage units, and grid stabilization systems. Practical implementations, such as superconducting DC feeder cables, already demonstrate both technical feasibility and commercial potential for enhancing efficiency and supporting large-scale railway electrification. • The use of superconductivity for applications in the railway sector is discussed and the most important contributions are identified. • The most important superconducting materials intended for large-scale applications are presented. • The principles of maglev are lined out, and several applications of superconducting maglev are illustrated and discussed. • Several examples where superconductivity can benefit the development of conventional, electrified railways are presented. • The main emphasis of the current research is devoted to the development of superconducting feeder cables for DC railway networks in France and Japan.