Study: the CATP is interested in the costs of hydrogen buses

Far from imposing or pushing one energy rather than another for buses, the central purchasing office for public transport (CATP) proposes to think about the best solutions to adopt for sustainable public transport, according to the local context. To this end, it has just updated its “Comparative study on the different motorizations of buses” initially published in 2014 and updated for the first time in 2017.

Created in 2011 by local elected officials and public transport companies to have an efficient purchasing service, the CATP, in terms of buses, will not take sides for one energy or the other. On the other hand, recalling the constraints that will weigh on these vehicles in terms of environmental footprint is one of its missions.

It appears that its catalog still offers, for the standard 12-meter models, the Man Lion’s City 12 C, Iveco Urbanway and Mercedes Citaro diesels. Facing them, CNG engines on the Scania Citywide and Iveco Urbanway, alongside hybrid architectures (Man Lion’s City diesel electric or CNG/electric, Volvo 7900 S-Charge).

There are also battery electric ones (Bolloré Bluebus, Iveco Heuliez GX 337 Elec, Mercedes eCitaro), Hess and Solaris trolleybuses, and the Safra Businova hydrogen. Even if the hydrogen solution appears to be the most expensive in the comparative table, it is not neglected by the purchasing group. In order not to make a blind choice, the organization invites you to answer a set of 13 questions which appears at the end of its 70-page document. To receive the latter, all you have to do is make the request on its website.


The authorities organizing regular or on-demand public transport know this very well: they must comply with constraints in order to green their fleets of coaches and buses. Above 20 of these vehicles, they are now called upon to include 50% of low-emission models when renewing vehicles. And this, until January 1, 2025 when they will then only have to buy the most virtuous machines in terms of their environmental footprint.

While a certain amount of flexibility is always relevant in small territories, the same is not true in those that have low emission zones (ZFE) or are subject to an atmosphere protection plan ( PPP). Today, the Euro 6 standard for buses requires emissions limited to 0.4 grams per kilowatt hour for nitrogen oxides, 1.5 g for carbon monoxide, 0.13 g with hydrocarbons and 0.01 g about particles. For CO2 emissions, the figures are, out of the vehicle, included in the range 0.973-1.203 kg/km, and, from well to wheel, included in the interval 1.212-1.497 kg/km.

Of the 27,607 buses identified in France on January 1, 2020, 10,251 units, or 37.1%, met the Euro 6 standard.

evolution seuils euro bus


Environmental Impacts: Comparisons

According to the figures communicated in its file by the central purchasing office, thermal buses (classic diesel, hybrid, or stuffed with alternative fuels B100 and XtL) subject residents to a noise level of between 72 and 77 dB (A).

Hydrogen-powered models have in common with battery-powered electric ones that they reduce vibrations and these nuisances: 65 and 72.2 dB(A). But also to reset emissions of nitrogen oxides, carbon monoxide and particles. On the other hand, it is very different concerning the carbon footprint. Reasoning from the well to the wheel, using the 1.212-1.497 kg/km range for diesels as a basis, the battery-electric, trolleybuses and hydrogen buses show 0.088, 0.115-0.165 and 0.330 kg/km respectively.

Hydrogen would therefore do less well than bioNGV (0.263-0.288 kg/km). However, the authors of the file specify that, for hydrogen, the figures are obtained with electrolysis according to the French energy mix. Take the fuel cell bus which circulates in the agglomeration of La Roche-sur-Yon, in Vendée. It is full at the multi-energy green station supplied with hydrogen by Lhyfe, which operates the Bouin wind turbines. The carbon footprint is exemplary for him, far from 0.330 kg/km. Moreover, the territories that favor H2 buses have the idea for the most part of preferably resorting to production from a renewable source. And not to be limited to a “decarbonized” gas, controversial at European level.

2 architectures

The CATP reminds that 2 hydrogen bus architectures coexist. With the first, the gas supply is the main source for operating the electric motor, after requesting a fuel cell. If there is a buffer battery, it is of modest size compared to the vehicle. This is not the case with a powertrain where the fuel cell serves rather as a range extender. With this second architecture, the lithium-ion pack, of a more substantial dimension, is brought to the level of a centerpiece.

technos bus h2

Hydrogen buses are at the very bottom of the CATP comparative table, for 2 reasons. It is the most expensive of the solutions, and, above all, it is classified at the “Beginning / Experimental” stage. Just like the alternative fuels B100 and XtL, by the way.

In electric, only the trolleybus is seen as “Mature”. A level shared with thermics running on diesel or natural gas. Battery buses and hybrid architectures are credited with an “Intermediate” status.

To oppose the different energies in terms of their budgetary weight, the purchasing group reasons in terms of ownership costs. This includes 3 expenses: acquisition, energy and preventive maintenance. The organization assumes that a bus, regardless of the energy that powers it, lasts an average of 15 years, and will total a mileage of 600,000 km at the end of this period, or 40,000 km per exercise.


Ownership costs still high for hydrogen buses

Regarding the average acquisition cost, the CATP aligns, for a total of 650,000 euros: 570,000 euros excluding tax for the base vehicle + 80,000 euros for options. The latter is an average value noted on diesel buses to add, for example, air conditioning, athermal glazing, various equipment, and benefit from specific openings (type and number of doors). With a downward trend, the price per kilogram of hydrogen retained is 9 euros excluding tax, including the aid of Ademe, but not the cost of the distribution station. Otherwise, this figure would have been raised to 10-14 euros excluding tax, depending on the installed power.

The consumption that served as the basis for the calculations is 8.5 kg per 100 km. This gives an energy budget of 459,000 euros excluding tax over 15 years. The cost of preventive maintenance (257,800 euros excluding VAT) takes into account the renewal of the fuel cell (after 5 to 10 years) and the battery (lifespan of between 7.5 and 10 years depending on chemistry).

That is a total average cost of ownership of 1,366,800 euros excluding tax, which does not include the refueling station with local hydrogen production (between 2 and 3 million euros excluding tax for 10 to 15 buses, or 3.4 to 4.5 million euros for double the number of vehicles), nor the envelope to adapt the workshop (between 60,000 and 100,000 euros per bay).

12 m hydrogen bus
Average acquisition cost €650,000 excluding tax
Energy cost €459,000 excluding tax
Average preventive maintenance cost €257,800 excluding VAT
TCO 15 years €1,366,800 excl. VAT
Cost/km 2.28 €

These 1,366,800 euros in ownership costs can also be calculated per kilometer: 2.28 euros excluding tax. These numbers are the highest in the table. To be compared to the 727,000 euros (1.21 euro per km) of the diesel model which serves as a reference. Electricity has taken over from bioNGV: 909,200 euros excluding tax (1.52 euro per km) for battery-powered buses and 936,000 euros excluding tax (1.56 euro per km) for trolleybuses, compared to 943,500 euros excluding tax with the biogas (1.57 euro per km).

It’s better on the cost side of the hybrids: 685,300 euros for the Mild Hybrid (1.14 euros per km), 706,300 euros (1.18 euros per km) for the Full Hybrid. However, they cannot compete in terms of environmental impact. Ditto for alternative fuels whose ownership costs are estimated at 761,000 euros (1.27 euros per km) for the B100 and 779,400 euros (1.30 euros per km) with the Xtl.

So why choose the hydrogen solution for buses? Go to the game of 13 questions, in the last part of the file, to find out. This may be due to the availability of a nearby refueling station or an electrolyser coupled with renewable energies, and/or an appetite for testing new energies.

etude catp


Analysis of a particular case

In an appendix to its study, the CATP evokes the case of the Briey basin, in Meurthe-et-Moselle, whose public transport is operated by the ST2B. A station with green hydrogen production and storage means are at the heart of a reflection in Audun-le-Romain. This is a good reason to adopt hydrogen buses locally. Especially since the territory is open to experimentation.

However, it already supports a methanization unit and is preparing to install 10 MW of photovoltaic panels. He could therefore just as easily choose bioNGV or electric for his public transport. And why not a mixture of the 3 solutions? The central purchasing advises against it, in particular because of the investments to be made to adapt depots and workshops, but also the skills to be had on site at the technician level.

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Study: the CATP is interested in the costs of hydrogen buses

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