An expensive undertaking, but Metz has taken the plunge: the first hydrogen buses enter service

After lengthy preparations and several vehicle procurement plans that ultimately fell through, 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 initial batch of a fleet renewal programme covering 34 vehicles in total. This year, 20 Solaris hydrogen buses – 14 articulated and six standard-length vehicles – will enter service on the Le Met’ network, while 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 in 2027 to serve the Mettis C line now under construction. With the latest entry into service, the programme has reached its first visible milestone after its original plans were substantially rewritten by the bankruptcy of Van Hool and another hydrogen bus procurement that eventually 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, followed by two more vehicles on 1 September. The fleet is being put into service gradually, and according to plans all Solaris vehicles belonging to the first phase will be in operation by All Saints’ Day, meaning that by late autumn 14 articulated and six standard 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 serve the new high-capacity rapid bus line scheduled to open in September 2027, 14 additional Solaris articulated buses will enter service; these will also be 18 metres long, but in a higher-comfort BHNS specification. Including these vehicles, 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 was by no means an overnight development, nor can the process be described as smooth. The programme’s first notable precursor dates back to March 2021, when a Van Hool A330 Fuel Cell demonstrator bus was tested in the city. Later plans became far more ambitious, and at one point three hydrogen bus projects were running in parallel.

The largest of these was linked to Mettis C. For the new rapid bus line, a tender was originally launched for the purchase of 13 hydrogen-powered, 24-metre, bi-articulated BHNS buses, which Van Hool won in 2023 with its Exqui.City FC model. The Belgian manufacturer was certainly not an unknown name in Metz by then: on the Mettis A and B lines, 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.

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

In parallel, two further hydrogen bus procurements were also under way. Metz ordered 14 articulated Solaris Urbino 18 hydrogen vehicles, while six standard-length Safra Hycity 12 buses were also planned. The latter delivery also failed to materialise, however, and the six Safras were ultimately replaced by Solaris Urbino 12 hydrogen buses. These two procurements together made up the 20-vehicle Solaris fleet whose first members have now entered service on routes L3 and L5.

Meanwhile, the Mettis C vehicle programme was handled separately. After Van Hool’s bankruptcy, the decision was made to procure 14 hydrogen buses of 18 metres instead of the original 13 bi-articulated vehicles, with Solaris again selected as the supplier. The roughly 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 is due to open in September 2027, when the Solaris Urbino 18 hydrogen buses specifically configured for this task are expected to enter service.

All this does not mean, however, that Metz intends to base the future of its entire bus fleet on hydrogen propulsion. In parallel, the metropolitan area is also planning a substantial 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 made according to the operational characteristics of each route.

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

For routes L3 and L5, which are now the first to switch to hydrogen operation, no such detailed, route-specific justification has been published. Both are part of Le Met’s high-traffic 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 primarily cites greater range and the resulting higher vehicle utilisation as arguments 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 may require up to around 20% fewer vehicles with hydrogen propulsion.

All this, however, comes with significant procurement costs. According to the Metz figures now published, a standard-length hydrogen bus costs around €800,000, while an 18-metre articulated vehicle costs approximately €1 million. The Solaris vehicles intended for Mettis C, also 18 metres long but in a higher-comfort and higher-specification BHNS version, are even more expensive, at around €1.1 million each. The high vehicle price is only one cost factor, however, since the infrastructure required for hydrogen production, compression, storage and refuelling also requires major investment, followed by ongoing operating costs.

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 80% owned by the local energy company UEM, with Eurométropole de Metz and John Cockerill, which also manufactures electrolysers, each holding 10%. The standalone investment value of the hydrogen production and refuelling infrastructure being built at Frescaty has not been disclosed, although the 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 production of more than 800 kilograms per day, with the latest statements indicating a daily capacity of between 800 and 900 kilograms. This will not serve buses alone: the metropolitan area’s fuel cell refuse collection vehicles will also receive locally produced hydrogen. Local production, however, had not yet started when the hydrogen buses entered service. The electrolyser is planned to be commissioned in autumn 2026, so during the interim period H2 Metz is purchasing renewable hydrogen from Air Liquide. The unsubsidised cost of local production is estimated at around €15 per kilogram.

This latter figure already gives a clear indication of the technology’s operating costs. A full refuelling of a standard-length fuel cell bus requires around 40 kilograms of hydrogen, while an articulated bus needs more than 50 kilograms. Based on Metz’s production cost of €15/kg, a single refuelling therefore represents roughly €600 worth of hydrogen for a standard bus and at least €750–800 for an articulated vehicle. Metz puts the vehicles’ range at around 300–500 kilometres on one fill, meaning that the benefits of high daily mileage and rapid refuelling come with considerable energy costs.

The difference is even more striking from the perspective of energy use. Producing 40 kilograms of hydrogen by electrolysis requires approximately 2.5 MWh of electricity. And this only covers the production of the hydrogen itself: compression, storage and refuelling involve further energy consumption. By comparison, 2.5 MWh of electricity is enough to provide the equivalent of the nominal battery capacity of a 400–500 kWh electric bus about five or six times. Assuming a range of roughly 300 kilometres on one charge, the same amount of electrical energy could theoretically be sufficient for around 1,500–1,800 kilometres of operation by a standard-length battery-electric bus. By contrast, the 40 kilograms of hydrogen produced from 2.5 MWh of electricity by electrolysis gives a fuel cell bus a range of only a few hundred kilometres. The actual figures for both technologies are, of course, influenced by losses in energy conversion, charging and propulsion, but the comparison clearly illustrates the significant difference in efficiency between the two energy chains.

Electrolysis also requires water of suitable quality. In theory, producing one kilogram of hydrogen requires at least around 9 litres of water, but with water treatment and process losses included, actual consumption may be higher. Producing a single 40-kilogram bus tank of hydrogen therefore requires, in itself, at least 360 litres of water treated to the quality required for electrolysis – effectively demineralised water purified 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; in addition to the electrolyser, it requires compressors, drying and water-treatment equipment, a high-pressure storage system, refuelling equipment, and complex safety and monitoring systems. The investment, operating and maintenance requirements of all these elements come on top of the already high purchase price of the vehicles. Compared with charging infrastructure for battery-electric buses, hydrogen supply requires a substantially more complex technological chain, elements of which will need refurbishment or replacement over time, meaning that significant costs must be expected in the longer term as well as at the initial investment stage. It is no coincidence that national and European Union subsidies still play a decisive role in the implementation of hydrogen bus programmes: alongside high vehicle prices, the infrastructure needed to produce, store and dispense the fuel also demands considerable additional investment.