Fuel Cell Systems for Rail Applications: Development Trends and Challenges

Besides battery electric powertrains, fuel cell electric powertrains are considered as a possible solution for zero local emission mobility for both road and rail vehicles. Depending on the particular use case, various components of the fuel cell system have to be designed to meet the customer requirements regarding system power, efficiency, cost, reliability, availability and durability. Apart from the scaling of one or several fuel cell stacks, the development process includes the design of the peripheral components in the air-, hydrogen- and coolant-paths of the fuel cell system.

Compared to the application of fuel cell systems in passenger cars and commercial vehicles, the implementation of fuel cell systems in railway vehicles affords advantages as well as new challenges.

The rail-bound traffic is characterized by approximately repeating driving cycles, since railway vehicles usually complete a daily schedule defined by the train operator. Improving the energy management for a particular train route can effectively reduce overall energy consumption. Furthermore, a majority of a fuel cell system’s waste heat can be utilized to heat the passenger compartment at low ambient temperatures. Despite the frequent stopping times in railway stations, degradation accelerating start-stop cycles of the fuel cell system can be reduced due to the high power demand of the auxiliary components and the possibility to charge the traction battery.

However, the long life cycle of rail vehicles, their demanding duty cycles and the goal to reach cost parity with diesel-powered trains pose major challenges. Compared to passenger cars and commercial vehicles with average operating periods of 8000 h respectively 25,000 h, the fuel cell stack and its peripheral components in rail vehicles should reach operating periods of up to 30,000–40,000 h. To meet these requirements, the degradation rate must be significantly reduced to prevent the replacement of the fuel cell stack or other system components before the end of their service life. Due to the need to recognize critical operating conditions and faults early as well as to predict the remaining useful lifetime and enable condition-based maintenance, the application of ‘Prognostics and Health Management’ (PHM) becomes increasingly important.