What to do when hydrogen vehicles burn?

If fuel cell technology becomes more widespread, hydrogen-powered vehicles will also be operated in tunnels and underground car parks in the future - and could catch fire there. This is why the International Fire Academy is involved in the European research project «HyTunnel-CS», which aims to develop hydrogen vehicles as safe as possible.

Hydrogen in the future?

Hydrogen-powered vehicles are a technological hope for climate protection. That is why work is being done worldwide on the further development of fuel cell technology, for which the European Union has initiated and financed numerous research programmes.

To the EU research programs:

One of these research projects is «HyTunnel-CS». Hy stands for hydrogen, and CS stands for confined spaces, i.e. rooms with limited access, such as underground car parks.

To the project «HyTunnel-CS»:

This project aims to develop hydrogen-powered vehicles that can be operated in underground transport systems at the same or even lower risk than fossil-powered vehicles. The project is financed by the public-private partnership Fuel Cells and Hydrogen Joint Undertaking (FCH) based in Brussels.

More about FCH:

Hydrogen vehicles soon to spread everywhere?

At the moment, hydrogen-powered vehicles still play a minor role. In a few years, however, they could be widespread, i.e. practically everywhere: not only on roads and rails and even in the air, but also in railway and road tunnels, railway stations, car parks, garages and carports. And even with the greatest technical reliability, hydrogen-powered vehicles will also be involved in accidents, which can lead to vehicle fires as well as incorrect operation or inadequate maintenance. Then everyone, even the smallest fire service, could be confronted with fires of hydrogen vehicles. Therefore, at the suggestion of the Fire Protection Research Center of the Karlsruhe Institute of Technology KIT, the International Fire Academy was invited to participate in the project «HyTunnel-CS». On the one hand, to bring in their expertise in the deployment field of underground transport systems. On the other hand, the International Fire Academy is also in demand in the development and conveyance of specialised tactics and techniques for firefighting.

Principle: Let it burn down in a controlled manner

From the fire service's point of view, hydrogen has two unpleasant properties: Firstly, the flames of burning hydrogen are very hot and barely visible to the naked eye. Secondly, unburned escaping hydrogen forms explosive gas-air mixtures which can be ignited by even very weak sparks.

The general procedure has been known for a long time. Thermal imaging cameras detect the flames. Or they can also be made visible by holding flammable objects, such as a broom, in the suspected flame area. To avoid explosions, hydrogen fires, like all gas fires, are burned off in a controlled manner while the environment is shielded.

The manufacturer's rescue data sheets provide information on the individual vehicle.

More difficult to answer is the question of how exactly to proceed if, for example, hydrogen escapes unburned from a vehicle tank in an underground car park. Here the representatives of the International Fire Academy are in close contact with the scientists of the participating universities and research institutes. Together they cover all relevant areas of science and technology in an interdisciplinary manner. Together they are trying to break down the latest findings from experiments and simulations into standard rules of engagement that are suitable for the fire services.

From rule to practice

As helpful as standard engagement rules are, they are not enough on their own to handle difficult operational tasks, because no rule can cover all possible situations in practice. So far, for example, it has been recommended to only approach burning hydrogen vehicles from the side because the meter-long hydrogen flames from a blowing tank are directed backwards or forwards. But how can this be done if the vehicle is parked in a parking bay in an underground car park and the neighbouring vehicles block the lateral access? Such issues are currently being discussed together with other firefighting schools and are the main topic of the parallel project «HyResponder», which, like the project «HyTunnel-CS», is financed by the European Union and the FCH. The «HyResponder» is led by the Ecole nationale supérieure des officiers de sapeurs-pompiers in Aix-en-Provence (France). One goal of the developers is to develop a course in which all fire services are ultimately to be familiarised with the tactics and techniques for coping with incidents with hydrogen vehicles.

Hydrogen will be one of many variants

It is still unclear how widespread hydrogen-powered vehicles will be. In any case, however, it is to be expected that more and more different types of drive will be ready for series production, to which the fire services have to react differently. The biggest problem, therefore, is to reconnoitre as quickly as possible whether it is a vehicle with large batteries, with fossil fuels, hydrogen, natural gas or liquefied natural gas in the tank.

It is true that the many types of drive can be identified from the outside through type designations or special labels such as Blue Cell (for fuel cells with hydrogen). However, these can become unrecognisable in an accident or fire.

A safe method of exploration is provided by the vehicle identification number (VIN). Based on these, it is possible to determine beyond doubt the type of drive of a damaged vehicle. This is why a working group of the International Fire Association CTIF is committed to making this VIN electronically accessible to the fire services. Ideally, it would already be sent to the dispatch centre with an automatic emergency notification from the e-call system. It would also be conceivable to record the VIN when entering a car park, for example. In the event of an incident, the fire service could then quickly determine how many vehicles with which types of drive are in the building.

Work on critical detailed issues

At the current stage of the project, it is to be expected that the fire services will be able to cope safely with incidents with hydrogen vehicles in some time. This is also helped by the fact that the safety features of fuel cell technology are to be continually optimised in the course of the «HyTunnel-CS» project. But at the moment there are still more open questions than first answers. A headache is, for example, the question of how to proceed with very heavily deformed accident vehicles. Because, as with electric vehicles, a cut in the wrong place can lead to nasty surprises. But answers will also be found to these questions.