Alternative powertrains for shunting locomotives - analysis of feasibility and limitations

Zero-emission powertrain technologies for shunting locomotives are becoming increasingly relevant as potential replacement candidates to diesel operated powertrains. We investigate the feasibility of zero-emission technologies in light of generic operational shunter locomotive profiles and available limited space and mass of a widely in use MaK G 1206 four axle center-cab shunting locomotive. Two generic shunting locomotive operational cycle profiles were defined based on a survey among German shunting locomotive operators: a pure shunting profile and a mixed shunting and mainline service profile. Daily energy demand at DC link level in both scenarios is similar (1,469 and 1,368 kWh respectively), but average power is higher in the mixed mainline/shunting profile. Powertrain candidates were fuel cell hybrid, battery electric, overhead wire battery electric, BiMode overhead battery electric and hydrogen internal combustion engine. Key powertrain component dimensioning for both scenarios is done using a hybridization tool incorporating volumetric and efficiency specifications of state-of-the-art railway components. The fuel cell hydrogen and overhead wire battery electric drivetrains can fulfill the energy and power requirements for the defined operational profiles, whereas the hydrogen internal combustion engine powertrain has limitations due to installation space restrictions in terms of hydrogen storage tanks. Advancements in energy storage technologies might influence the applicability of alternative powertrain systems, not only of hydrogen-based but also of battery-based propulsion systems. Further research and demonstration projects on zero-tailpipe emission shunting locomotives are recommended