Fuel cell buses emit no air pollutants or environmentally harmful gases. They can run an entire day without the need for refueling and offer operators the same flexibility as diesel vehicles. Fifty-four fuel cell buses and nine hydrogen filling stations were tested in day-to-day operation during the Clean Hydrogen in European Cities project from 2010 to 2016. The results were presented in London at the Zero Emission Bus Conference on Nov. 30, 2016.