A new €500m ($530m) fleet of 27 hydrogen trains was scheduled to be in operation on four railway lines to the German city of Frankfurt last December, but only 12 trains are currently in use on one line, with the full complement not expected to be ready until September at the earliest.

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The ongoing saga reads like a comedy of errors.

The first six Coradia iLint H2 trains delivered by manufacturer Alstom last year proved to be defective — requiring retrofitting of new hardware and software components — although two did go into service on the RB15 line on the planned start date, 11 December 2022.

Then, many of the diesel locomotives brought in as temporary replacements for the missing trains also had problems, forcing the local rail operator, Start Deutschland, to put on a replacement bus service that has now been in place for the past six months — the cost of which is apparently being charged to Alstom.

Local press also reported difficulties with the new hydrogen refuelling station in the winter, but Hydrogen Insight was unable to verify those.

According to RMV, the local-authority-owned transport authority that ordered the hydrogen trains, diesel locomotives have finally been removed from the RB15 line, with the 12 functioning H2 trains sufficient for its operation.

However, the bus replacement service is still needed on the mountainous route — but not for a lack of working trains.

The months of problems and lack of working trains — not to mention the inability to train some of the drivers on the new H2 locomotives due to a lack of them being available — meant that shifts could not be planned, and the uncertainty has proved too much for many employees.

Twenty of the 60 drivers employed by Start on the Taunusbahn — which connects Frankfurt with other cities, towns and villages in Hesse state — have resigned this year, while almost a fifth are claiming to be too ill to work.

“Until things are stable again with enough staff, we’ll keep the rail replacement [bus] service going,” RMV managing director Knut Ringat told the Frankfurter Allgemeine newspaper.

Start, a subsidiary of the national railway operator, Deutsche Bahn, is now desperately trying to hire new train drivers, including those starting a new career who will need to be fully trained.

The fact that the RB15 line is currently closed until 11 June to allow updates of the route’s control and safety technology may have also been a reason to keep the buses going — not to mention the ongoing problems with non-functioning toilets on the new hydrogen trains.

On top of that, the electronic noticeboards on the RB15 line are not providing accurate live information about arrival times, causing passengers to wait for trains that don’t arrive, and occasionally making them dash to get a replacement bus, before running back if the train pulls in a few minutes late.

But one of the strangest things about the 42km RB15 line is that roughly half of the track — from Frankfurt to Friedrichsdorf — is already electrified with overhead power lines, and much of the rest of the route — another 18km from Friedrichsdorf to Usingen — will also be electrified by the end of the year.

This is being done in order to allow the electric S-Bahn 5 line — which follows the same route as the RB15 to Friedrichsdorf — to be extended to Usingen, which is only five stops from the end of the RB15 line.

In fact, the entire RB15 was closed for several weeks in January and February to allow for the felling of trees to enable the new overhead lines to be installed.

So why were hydrogen trains needed in the first place?

Ringat told the Frankfurter Allgemeine that a tunnel between two of the stations past Usingen meant that overhead power lines could not be installed there, making it impossible to electrify the whole of the RB15.

It also seems that the entire project is a pilot scheme meant to showcase hydrogen rail technology.

H2-powered rail is usually a more expensive option than line electrifiction or battery hybrid trains, which use batteries to keep trains running when there are gaps in overhead cables, although circumstances vary depending on geography.

One recent study by the German state of Baden-Württemberg found that hydrogen trains would be up to 80% more expensive than purely electric options over a 30-year period.

Alstom is due to deliver four more hydrogen trains this month, with the remainder coming in September — nine months after its contracted delivery time of December 2022.

A spokesman for the French manufacturer told Frankfurter Allgemeine: “Due to the delivery difficulties caused by the Corona pandemic and the Ukraine war, key components for the series trains were no longer of the quality agreed with the suppliers.”

The ongoing debacle — described by the newspaper as “misery” for the fed-up passengers — has prompted RMV to offer free travel on the RB15 throughout August and September.

“Passengers have experienced an incredible amount of bad public transport for six months,” Ringat told the German newspaper, explaining that the free rides will “create positive emotions again” for passengers.

Some positivity is definitely needed, as the remaining 15 Alstom trains will be run on the other three Taunusbahn lines run by Start — the RB11, 12 and 16 — which are currently operating entirely with diesel locomotives.

The H2 being used for all of the network’s hydrogen trains is produced as a chemical by-product at the nearby Höchst Industrial Park.

According to RMV, this production is powered by the local power grid, which gets about 50% of electricity comes from renewable energy sources. The price being paid by RMV for this hydrogen is “well below market price currently quoted elsewhere”.

Start only took over the operation of the Taunus network from Hessian State Railway, in December 2022, when the entire hydrogen train fleet — the largest in the world — was supposed to be delivered.