Review and Comparison of Worldwide Hydrogen Activities in the Rail Sector with Special Focus on On-board Storage and Refueling Technologies

"This paper investigates hydrogen storage and refueling technologies that were used in rail vehicles over the past 20 years as well as planned activities as part of demonstration projects or feasibility studies. Presented are details of the currently available technology and its vehicle integration, market availability as well as standardization and research and development activities. A total of 80 international studies, corporate announcements as well as vehicle and refueling demonstration projects were evaluated with regard to storage and refueling technology, pressure level, hydrogen amount and installation concepts inside rolling stock. Furthermore, current hydrogen storage systems of worldwide manufacturers were analyzed in terms of technical data.
We found that large fleets of hydrogen-fueled passenger railcars are currently being commissioned or are about to enter service along with many more vehicles on order worldwide. 35 MPa compressed gaseous storage system technology currently dominates in implementation projects. In terms of hydrogen storage requirements for railcars, sufficient energy content and range are not a major barrier at present (assuming enough installation space is available). For this reason, also hydrogen refueling stations required for 35 MPa vehicle operation are currently being set up worldwide.
A wide variety of hydrogen demonstration and retrofit projects are currently underway for freight locomotive applications around the world, in addition to completed and ongoing feasibility studies. Up to now, no prevailing hydrogen storage technology emerged, especially because line-haul locomotives are required to carry significantly more energy than passenger trains. The 35 MPa compressed storage systems commonly used in passenger trains offer too little energy density for mainline locomotive operation - alternative storage technologies are not yet established. Energy tender solutions could be an option to increase hydrogen storage capacity here."