Railway - Why is it important?
Economics of direct-current electrified railway in densely populated megapolices can be drastically improved with HTS cables. When train frequency reaches ~10 trains per hour, superconducting systems start improving energy efficiency and/or reducing capital costs. Huge benefits can be obtained if energy recuperation is used (energy generated by decelerating trains is sent to accelerating trains via superconducting feeder cable). Prototypes are being currently tested in railway grid of Tokyo and Paris. Further, some versions of maglev (magnetic levitation) trains are using high-field superconducting magnets for suspension. Although HTS-related activity for maglev is still in its R&D stage, it can create significant demand for HTS after prototypes are successfully tested and their viability is secured. The use of HTS would simplify cryogenics and decrease cost.
What's holding us back?
A long process of rigorous tests and certification is intrinsic to any passenger transit technology, railway is of course no exception. At least for feeder cables, this process has started in Japan and France and the positive outcome should create a path for commercialization of technology.
Aviation - Why is it important?
HTS enables light-weight propulsion motors, generators, transformers and high-power cables. These constituents of electric powertrain are often named as the key enabling technologies of the decarbonization of the aviation. The use of superconductors has been proven in multiple studies to be the only viable way to either hybrid propulsion or fully electric scheme at megawatt scale. The on-board voltage of the airplane is naturally limited to few hundred Volts by the necessity to exclude any possibility of arcing even at reduced atmospheric pressure. This obstacle makes superconductor case even more appealing because superconductors are able to transport electric current at record density. It’s worthwhile to note that there’s significant synergy with a task of using hydrogen as a carbon-free aviation fuel. This would significantly simplify cryogenic system for superconductors because due to its low density, hydrogen fuel can be used only in a liquified form.
What's holding us back?
Multiple studies are underway to solve remaining technological challenges and enable megawatt-class superconducting powertrain for aviation. The current level of TRL is quickly approaching lab-scale verifications. However, even if technological issues are solved and the new equipment reaches necessary technological maturity, there’s still a lot of work to be done to enable its use in aviation: certification, pilot training etc. These processes are taking years to accomplish. Many experts however believe that the urgent demand for decarbonized flight, which is already reflected in official documents of international aviation, will propel this direction of development.