Energy comparison between mechanical, diesel-electric and hybrid drives for buses using a simulation program

A simulation software was developed in cooperation with the Renault Truck and Bus Research Department to take into account different drivelines for increased accessibility features on urban buses such as: (a) a conventionnal internal combustion engine powered bus; (b) a diesel-electric driveline bus; and (c) a series hybrid driveline bus. This paper describes drivelines, computing models, bus usage and the corresponding results obtained (in terms of consumption, emissions and performance) for the three different cases mentioned above. The results of the calculations, using the same parameters (driving schedules, vehicle load, etc.) imply that the diesel-electric driveline is comparable to the conventional one. The hybrid design enables the vehicle to be operated in the all-electric mode in city centres, causing no local pollutant emission, and offers the possibility of a switch from petroleum to electricity. Though fuel consumption with no energy switch is higher than those of conventional designs, emissions are found to be lower for the hybrid driveline in all cases studied.