https://www.wabteccorp.com/locomotive/alternative-fuel-locomotives/flxdrive
Wabtec website provides details of their battery electric locomotive now under trials for BNSF in Stockton, CA. Battery is charged either in dynamic braking or by wayside chargers. Batteries provide full power for 30 to 40 min. They claim significant increase in efficiency.
Website also has information on their natural gas fired locomotive which can carry fuel in a tender and use either LNG or compressed NG. Engine can also switch to diesel fuel.
Doesn’t sound like fuel cells in this model.
They are bragging about rebuilding the first of 50 diesel locomotives for CN switching from DC to AC and increasing locomotive power and efficiency.