Comparison of Well-to-Wheel Efficiencies for Different Drivetrain Configurations of Transit Buses

Document Type

Journal Article

Publication Date


Subject Area

place - urban, mode - bus, technology - alternative fuels, technology - emissions


energy efficiency, diesel buses, hybrid electric buses, fuel cell electric buses, battery electric buses (BEBs)


The transportation sector, especially road transport, must reduce its energy consumption and emissions significantly. This requirement also applies to road-bound public transport, which uses mainly diesel buses. A reasonable measure for reaching this goal is to electrify the vehicle’s drivetrain. During the past decade, several alternative technologies have evolved, namely, hybrid electric buses, fuel cell electric buses, and battery electric buses (BEBs). For a comparison of their energy efficiency, both the drivetrain’s efficiency and the efficiency of the energy supply must be examined to determine well-to-wheel efficiency. This paper attempted to compare seven drivetrains for urban transit buses: diesel, natural gas, diesel–electric, hybrid electric (series and parallel), fuel cell electric, battery electric, and trolley bus. This comparison will become the main part of a more extensive model that supports decision making in bus procurement processes. The model will be as simple as possible. This factor makes it suitable also for the practitioner’s use. Therefore, an analytic approach instead of a simulation tool was used. The model’s outcomes were both total and specific energy consumption of four generic bus types operating on a dedicated bus line. The result of the study found that the trolley bus, closely followed by the BEB, was the most efficient, even when the share of renewable energy in electricity generation was low. The possibility to reduce specific energy consumption by increasing the occupation rate is outlined as well.


Permission to publish the abstract has been given by Transportation Research Board, Washington, copyright remains with them.