Definition of "fuel cell"

A new energy source claimed by Mr. Coultas to be potentially applicable to locomotives is the fuel cell, now becoming more commonly known as the fuel battery. [...] The fuel cells which are furthest advanced in engineering development today use hydrogen as the fuel.

1962 February, “Talking of Trains: Fuel battery locomotives?”, in Modern Railways, page 87

The Mako is powered by a sealed hydrogen-oxygen fuel cell, and includes a small element zero core. While not large enough to nullify the vehicle’s mass, the core can reduce it enough to be safely air-dropped.

2008, BioWare, Mass Effect (Science Fiction), Redwood City: Electronic Arts, PC, scene: Vehicles: M35 Mako Codex entry

Fuel cells have a shorter lifetime than batteries and their overall efficiency of a hydrogen train is much less - recent figures from Stadler show that just 25% of the energy reaches the wheels for a hydrogen train, compared with 80% for conventional electric tration or around 68% for a battery-electric train.

2023 August 23, Ben Jones, “A Fast Charge to DMUs' demise?”, in RAIL, number 990, page 30