City bus powered by hydrogen fuel cell and flywheel energy storage system

This paper presents the design and application of hybrid power train for city bus with zero greenhouse emissions and high work efficiency. The vehicle system configuration is based on two separately electric driven wheels powered by an hybrid unit composed by a hydrogen fuel cell and flywheel energy storage system. Numerical models were built to simulate the powertrain components and to downsize the fuel cell power satisfying the transient loads by the flywheel energy storage device. A simulation of the city bus (15 passengers of carrying capacity) was run over the European urban standard drive cycle in order to size the powertrain components. Finally the hydrogen production by water electrolysis was considered and consumption and CO₂ emission per bus were estimated.