A costly move, but Metz has taken the plunge: first hydrogen buses enter service

After lengthy preparations and several vehicle procurements that fell through along the way, scheduled hydrogen bus operation has begun in Metz. The first fuel cell Solaris buses entered service on the French city’s public transport network at the end of August, forming the first part of a fleet development programme covering a total of 34 vehicles. This year, 20 Solaris hydrogen buses – 14 articulated and six rigid vehicles – will enter service on the Le Met’ network, while in 2027 a further 14 high-capacity, 18-metre BHNS (Bus à Haut Niveau de Service) vehicles, designed for a high-quality, BRT-type bus rapid transit system, will arrive to operate the Mettis C route now under construction. The launch marks the first visible milestone in a programme whose original plans were significantly reshaped by the bankruptcy of Van Hool and by another hydrogen bus procurement that ultimately failed.

The first three hydrogen buses began carrying passengers on 31 August on routes L3 and L5 of the Le Met’ network, which provides public transport in Metz and the surrounding area, and were joined by two more vehicles on 1 September. The fleet is being introduced gradually: according to plans, all Solaris buses belonging to the first phase will be in service by All Saints’ Day, meaning that by late autumn 14 articulated and six rigid hydrogen buses will be running on the Metz network.

In addition to the 20 vehicles now entering service, a further hydrogen bus fleet specifically intended for Mettis C is also on the way. To operate the new high-capacity bus rapid transit line, due to launch in September 2027, a separate batch of 14 Solaris articulated buses will enter service; these will also be 18-metre vehicles, but in a higher-comfort BHNS specification. Together with these, Metz’s hydrogen bus fleet could comprise a total of 34 fuel cell buses by the end of 2027.

The introduction of hydrogen propulsion in Metz did not happen overnight, and the process can hardly be described as smooth. The programme’s first visible precursor dates back to March 2021, when a Van Hool A330 Fuel Cell demonstrator bus was trialled in the city. Later plans became far more ambitious, and at one point three parallel hydrogen bus projects were under way.

The largest of these was linked to Mettis C. For the operation of the new bus rapid transit line, a tender was originally issued for 13 24-metre, bi-articulated hydrogen-powered BHNS buses, which Van Hool won in 2023 with its Exqui.City FC model. The Belgian manufacturer was by then far from unknown in Metz: on Mettis lines A and B, 24-metre Van Hool Exqui.City diesel-electric hybrids still form the backbone of the fleet, with around 30 examples in service. Their replacement is also on the agenda, though under a separate fleet renewal programme.

The procurement of the new Van Hool vehicles intended for Mettis C had already moved well beyond the planning stage; in 2023, the Eurométropole de Metz, the metropolitan authority for the Metz urban area, paid the Belgian manufacturer an advance of around €1.45 million for the vehicles. Van Hool’s bankruptcy in 2024, however, made fulfilment of the contract impossible, meaning that not only did a new supplier have to be found, but the original vehicle concept also had to be reworked. The 24-metre bi-articulated vehicles were eventually abandoned, and by 2025 the plan for Mettis C was to procure 14 18-metre hydrogen-powered BHNS buses instead.

At the same time, two further hydrogen bus procurements were also under way. Metz ordered 14 Solaris Urbino 18 hydrogen articulated buses, while the purchase of six rigid Safra Hycity 12 vehicles was also planned. The latter delivery also fell through, however, and the six Safra buses were ultimately replaced by Solaris Urbino 12 hydrogen vehicles. These two procurements together make up the 20-vehicle Solaris fleet whose first members have now entered service on routes L3 and L5.

The Mettis C vehicle programme, meanwhile, was handled separately. Following Van Hool’s bankruptcy, the decision was made to procure 14 18-metre hydrogen buses instead of the original 13 bi-articulated vehicles, and Solaris was again selected as the supplier. The approximately 10-kilometre Mettis C line will provide a high-capacity link between Metz, Montigny-lès-Metz and Marly, serving around 21 stops in total. The new line will open in September 2027, when the Solaris Urbino 18 hydrogen buses designed specifically for this duty are expected to enter service.

None of this means, however, that Metz is basing the future of its entire bus fleet on hydrogen propulsion. In parallel, the metropolitan area is also planning a major battery-electric bus programme, under which a total of 99 fully electric buses are to be procured. The two technologies are therefore not being treated as mutually exclusive alternatives; instead, the choice is being made according to the operating characteristics of individual routes.

In the case of Mettis C, the use of hydrogen was justified specifically by the operating conditions. Vehicles on the high-capacity bus rapid transit line will have to be available for long periods each day and cover high daily mileages, while the overnight shutdown is limited to roughly the period between midnight and 7 a.m. Battery-electric operation was also examined, but this would have required opportunity charging during the day in addition to depot charging. One planned location for this was the Place Mazelle area, where the installation of the necessary charging equipment was complicated by townscape and heritage-protection considerations. For Mettis C, the Eurométropole therefore ultimately opted for hydrogen operation.

No such detailed, route-specific justification has been provided for routes L3 and L5, which are now the first to switch to hydrogen operation. Both form part of Le Met’s busy LIANE network, so high daily availability and substantial mileage presumably also played a role here, although the operator has not officially confirmed this. In any case, the current entry into service does not mean that the 20 new Solaris buses will operate exclusively on these two routes in the longer term.

Metz cites greater range, and the resulting higher vehicle utilisation, as the main argument in favour of hydrogen operation. According to the operator’s calculations, an articulated hydrogen bus can cover around 400–500 kilometres between refuellings, while the battery-electric buses examined for comparison are assumed to have a range of 250–300 kilometres. On this basis, they calculate that providing the same level of service could require up to around 20% fewer vehicles with hydrogen propulsion.

All of this, however, comes with significant procurement costs. According to the latest figures from Metz, a rigid hydrogen bus costs around €800,000, while an 18-metre articulated vehicle is approximately €1 million. The Solaris buses intended for Mettis C, also 18 metres long but in a higher-comfort and higher-equipment BHNS specification, are even more expensive, at around €1.1 million each. The high vehicle price is only one cost factor, however, as the construction and subsequent operation of the infrastructure required to produce, compress, store and dispense hydrogen also require substantial investment.

In this respect, Metz does not simply intend to rely on an external supplier: a complete local hydrogen production and refuelling infrastructure is being built in the Frescaty area. H2 Metz, the company set up to deliver the project, is owned 80% by the local energy company UEM, and 10% each by the Eurométropole de Metz and John Cockerill, which also manufactures electrolysers. The standalone investment value of the hydrogen production and refuelling infrastructure being built at Frescaty has not been disclosed, although early plans for the Metz hydrogen programme earmarked around €8 million for production and supply infrastructure.

The central element of the system is a 2.5 MW electrolyser, which will produce hydrogen using electricity from renewable sources. The facility has been sized for daily production of more than 800 kilograms, with the latest statements referring to a daily capacity of between 800 and 900 kilograms. This will not be used exclusively to supply the buses: the metropolitan area’s fuel cell refuse collection vehicles will also receive locally produced hydrogen. Local production, however, had not yet begun when the hydrogen buses entered service. Commissioning of the electrolyser is planned for autumn 2026, so during the interim period H2 Metz is purchasing renewable hydrogen from Air Liquide. The cost of local production without subsidies is estimated at around €15 per kilogram.

That figure alone gives an indication of the operating costs of the technology. A full tank for a rigid fuel cell bus requires around 40 kilograms of hydrogen, and an articulated bus more than 50 kilograms. At Metz’s production cost of €15/kg, this means roughly €600 worth of hydrogen for a single refuelling of a rigid bus, and at least €750–800 for an articulated vehicle. Metz puts the vehicles’ range at around 300–500 kilometres on a full tank, meaning that the benefits of high daily mileage and rapid refuelling come with a considerable energy cost.

The difference is even more striking when viewed from the perspective of energy use. If around 62.5 kWh of electricity is assumed for each kilogram of hydrogen produced by electrolysis, producing 40 kilograms of hydrogen requires approximately 2.5 MWh of electricity. And this is only the production of the hydrogen itself: compression, storage and dispensing require additional energy. By way of comparison, 2.5 MWh of electricity could provide the equivalent of the nominal battery capacity of a 400–500 kWh electric bus around five to six times. If a range of approximately 300 kilometres per full charge is assumed, the same amount of electricity would theoretically be enough for a battery-electric rigid bus to cover around 1,500–1,800 kilometres. By contrast, the roughly 40 kilograms of hydrogen produced by electrolysis from 2.5 MWh of electricity provides a fuel cell bus with a range of only a few hundred kilometres. Actual figures for both technologies are affected by losses in energy conversion, charging and the driveline, but the comparison clearly illustrates the significant difference in efficiency between the two energy chains. While battery-electric propulsion typically achieves an overall grid-to-wheel efficiency of around 80%, fuel cell propulsion using hydrogen produced by electrolysis is generally put at around 25–35%.

Electrolysis also requires water of suitable quality. In theory, producing one kilogram of hydrogen requires at least around 9 litres of water, but actual consumption may be higher once water treatment and process losses are taken into account. Producing a single 40-kilogram bus tank of hydrogen therefore requires, at a minimum, 360 litres of water treated to the quality required for electrolysis – in practice, demineralised water stripped of mineral content.

The costs of hydrogen operation do not end at the electrolyser, either. In practice, the production plant is a small industrial facility: alongside the electrolyser, compressors, drying and water-treatment equipment, a high-pressure storage system, dispensing equipment, and complex safety and monitoring systems are also required. The investment, operating and maintenance requirements of all these elements are added to the already high purchase price of the vehicles. Compared with charging infrastructure for battery-electric buses, hydrogen supply requires a considerably more complex technological chain, individual elements of which will need refurbishment or replacement over time. As a result, significant costs must be expected over the longer term as well as in the initial investment. It is no coincidence that national and European Union subsidies still play a decisive role in the implementation of hydrogen bus programmes: in addition to the high vehicle price, the infrastructure required to produce, store and dispense the fuel also demands substantial additional investment.