Conceptual Design and Modelling of a Fuel Cell Pedal Assisted Bicycle.

Pedal Assisted Bicycles (PAB) popularity is fast growing in urban areas due to their low energy consumption and environmental impact. In fact, when electrically moved, they are zero emission vehicles with very low noise emissions as well. These positive characteristics could be even improved by coupling a PAB with a fuel cell based power generation system, so increasing the vehicle autonomy without influencing their emissions and consumption performances. In this paper a conceptual Fuel Cell Pedal Assisted Bicycle (FC-PAB) design with compact metal hydride hydrogen storage is analysed by means of a mixed experimental and numerical approach. Even though the power source integration for such a vehicle is simpler than that for a car, it still represents a challenging effort maximizing PAB vehicle autonomy and minimizing, at the same time, its weight. The performances of the polymer electrolyte membrane (PEM) FC based energy production systems for these applications are analysed by means of a simulation model able to describe the performance of all the system components from the on board energy storage to the road load. To increase the significance of the results, comparisons are made with respect to a reference driving cycle, in order to simulate a city trip comprehensive both of flat and hilly parts. Model predictions have proved to be able to simulate system behaviour and could be used to design system characteristics as well as to define its control system. Results show that FC-PAB reaches the pursued targets in terms of weight (comparable with the weight of the same bicycle powered by an electric motor fed by batteries) and autonomy (about 200 km under the conditions defined by reference driving cycle), still being zero local emissions and noiseless.