A study into the real-world operation of zero-emission buses in the northeastern Italian province of South Tyrol (officially known as Bolzano) has found that its battery-electric buses were 2.3 times cheaper to run per kilometre than hydrogen fuel-cell equivalents, on average.

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Eurac Research, a local private research institute, collected daily operating data from the 16 hydrogen fuel-cell electric buses (FCEB) and five battery-electric buses (BEB) operated by local public transport company SASA between January 2021 and April 2022.

The institute’s new report into its findings, published in the Journal of Energy Storage, concluded that the FCEBs cost an average of €1.26 ($1.37) per km to run, compared to €0.55/km for the BEBs.

“This means that, when it comes to cover the same distance, the running costs of FCEBs are 2.3 times higher than those of BEBs,” says the study, entitled Monitored data and social perceptions analysis of battery electric and hydrogen fuelled buses in urban and suburban areas.

The report explains that the FCEBs were powered by green hydrogen produced in-house, and while it does not explicitly state that the electricity used by the BEBs was renewable, it does point out that 89.9% of the mountainous region’s power comes from clean hydroelectricity.

Because the researchers were not informed about the actual energy costs over the course of the 16-month data-collection period, their cost assumptions were based on publicly available information: €13.80/kgH2 from SASA’s electrolyser, and the €0.40/kWh for local public recharging (even though the operator’s in-house electric charging points may well be cheaper).

Hydrogen consumption was then converted to kWh using a conversion factor of 33.33kWh/kg, the lower heating value of H2.

SASA’s two BEB models, both manufactured by Poland’s Solaris, were found to have tank-to-wheel (TTW) efficiencies of 137 and 153.80kWh per 100km, while the two FCEB models — made by Solaris and Mercedes-Benz — had average efficiencies of 310.24 and 335.75km per 100km, respectively, figures that are between two and 2.45 times lower than the battery buses.

And this does not include the energy losses from converting renewable electricity to hydrogen.

“This decrease of efficiency has a direct impact on the economic performance of the two [H2] bus models,” says the report. “Data suggests that driving FCEBs is between 2.12 times to 2.56 times more expensive per km than driving a BEB, considering only monitored TTW efficiency and fuel cost.

“However, both technologies permit a strong reduction in CO2 emissions, if compared to hybrid electric buses, ICEBs [internal combustion engine buses] and compressed natural gas buses.”

SASA is the main bus operator in South Tyrol, owned by the local of municipalities of Bolzano, Merano and Laives and the autonomous province of Bolzano, which currently operates about 300 buses.

The province aims to make all its public buses emissions-free by 2030, with 180 FCEBs and 210 BEBs.