Austrian Federal Railways (OEBB) and Siemens Mobility have developed an environmentally friendly train that is a hybrid electric-battery multiple unit: the Cityjet eco. The first runs of the Cityjet eco in real passenger operations have brought valuable insights and give a positive prognosis for the future.

OEBB Cityjet Eco Testing

Between 17 October and 15 November the prototype train with its electro-hybrid battery drive was put through its paces on non-electrified routes in Upper Austria. Carbon-neutral solutions such as the Cityjet eco are ideal for routes that are not yet electrified or where this is not feasible. Atop the train is a battery system that charges via a pantograph on electrified sections. Compared to diesel vehicles, the OEBB Cityjet eco can then cover non-electrified stretches without emissions and, additionally, much more quietly.
source= https://railway-news.com/oebb-tests-cityjet-eco-with-positive-results/