A fleet of 25 hydrogen fuel cell buses in the Polish city of Poznań was unexpectedly forced out of service on Monday morning, with all units experiencing simultaneous failures. The breakdown left city officials scrambling to deploy diesel buses while the issue is being investigated, Hydrogen Insight and Sustainable Bus reported.
MPK Poznań, the city’s public transport operator, confirmed that the failure affected all 25 hydrogen buses at the same time, prompting immediate collaboration with Solaris, the Polish bus manufacturer, and the city’s hydrogen supplier.
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“Around the same time, onboard systems on all hydrogen buses signaled a failure, making it impossible to continue operations,” an MPK Poznań spokesperson told Hydrogen Insight. “We are working closely with Solaris and our fuel supplier to identify the root cause.”
According to Sustainable Bus, the preliminary investigation suggests that fuel purity may be at fault. “The most likely cause of the malfunctions in several hydrogen buses in Poznań is poor fuel/hydrogen quality,” MPK Poznań stated. Another city official told local newspaper Wyborcza that hydrogen used for the buses must have a purity level of 99.97%. “This means that the hydrogen can only contain 0.03% of other gases. Even slight contamination could lead to operational issues,” the official added.
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The incident raises fresh concerns about the viability of hydrogen-powered public transport. Solaris, which has a dominant 65% share of the EU hydrogen bus market, is now under pressure to determine whether the failure stemmed from fuel quality, vehicle design, or another technical issue.
The European market for hydrogen buses remains small despite recent growth. In 2024, 378 hydrogen fuel cell buses were registered in the EU—an 82% increase from the previous year, according to Hydrogen Insight. However, hydrogen buses account for only a fraction of the market compared to battery-electric alternatives. Of the roughly 35,000 city buses registered in the EU last year, about 49% were zero-emission, with battery-electric buses making up nearly 16,750 units.
Solaris and Poznań city officials have not yet provided a timeline for when the hydrogen fleet will be back in operation.