Hydrogen fuel-cell powered train passes a solar farm near Geestenseth on the line between Bremerhaven and Buxtehude in Lower Saxony, Germany. This is one of two prototype Coradia iLINT trains, introduced in 2018, that operate the world's first regular passenger service using hydrogen fuel-cell technology. The fuel cells produce electricity that power the train's electric motors. Producing no harmful emissions, hydrogen fuel-cells emit only water vapour, formed as hydrogen and oxygen combine. The photovoltaic cells in the background (not related to the railway) produce electricity, which can potentially be used to produce hydrogen from water by electrolysis. This could be used to illustrate how renewable energy could power railways.