Decarbonization of public transport

A fast decarbonization of vehicles is needed to reach the set CO2 emission reduction targets in Europe, Italy, and South Tyrol. Public buses contribute only to a very limited way to the overall transport emissions. But public buses are driving many kilometers in their lifetime, they emit a relevant part of their emissions in urban areas and have a high visibility and close contact with the public. Therefore, the transition to zero emission buses plays an important role in the overall transition to zero emission transport.

Within this context the South Tyrolean Transport Agency (STA) wanted to evaluate the possibilities of converting several hundred buses to zero emissions in the coming years. To evaluate the specific South Tyrolean context a cooperation with the Institute for Renewable Energy of Eurac Research was set up. Main questions were if a transition towards zero emission buses is possible for all lines. And which technology (battery electric or hydrogen) could cover which line.

Researchers analyzed the state of the art of zero-emissions buses, all South Tyrolean intercity bus lines and their timetables. They then developed a simulation tool to calculate the compatibility of zero‐emission technologies with the current needs of the public transportation. To do so, a model has been set up based on the vehicle’s energy balance. The energy consumption has been evaluated based on the physical characteristics of the single bus line (distance and altitude), climatic conditions and its timetables. As such the model can be implemented in mountainous areas and on intercity lines allowing the specific energy consumption.

“Most of the feasibility studies concerning zero-emission buses, electric and hydrogen, refer to urban lines, while this study concerns intercity lines considering distance, altitude difference and climate conditions” says Andrea Grotto, co-author of the work.

“We expected to see that shorter lines could be covered by both technologies and that longer lines could be covered be hydrogen buses only. But our simulations did not confirm this hypothesis. In fact, they suggest that both technologies are feasible to substitute the diesel buses. To do so the correct bus types must be chosen, and a feasible charging / refueling infrastructure must be set up involving depot and opportunity charging” says Wolfram Sparber, Head of Institute and lead author of the study.

The study has recently been published in the World Electric Vehicle Journal of MDPI and can be downloaded under the following link. At present the researchers from the institute for renewable energy carry out a similar study for the public transport around Lago Maggiore in cooperation with VCO Trasporti and are collecting real world bus consumption data to further enhance the level of adequacy of the simulations.