Electric car burns in the tunnel: endurance test for the infrastructure

++ HANDOUT ++ STEIERMARK: BURNING E-CARS - REAL FIRE TRIALS IN "CENTER ON THE MOUNTAIN" IN IRON ORE

© APA / TU GRAZ / LUNGHAMMER / LUNGHAMMER

Images of burning electric vehicles keep making the rounds and unsettling. In any case, Austrian tunnels can withstand the fire load of battery-powered cars, according to fire tests conducted by the You Graz in the “center on the mountain” in Eisenerz, Upper Styria. However, according to the experts, comprehensive real fire tests are urgently needed in order to know what the risk is in parking garages or with e-buses and trucks.

Tunnels are also being used more and more by electric cars. But what happens if the battery of an electric vehicle catches fire? How hot does it get, which gases are produced and what are the risks to people who are in the tunnel and the emergency services? in the Tunnel research center “Zentrum am Berg” at the Montan University Leoben Under the leadership of Graz University of Technology, experts used large-scale fire experiments to investigate the effects of fires in electric vehicles on the safety of tunnel users and the infrastructure.

++ HANDOUT ++ STEIERMARK: BURNING E-CARS - REAL FIRE TRIALS IN "CENTER ON THE MOUNTAIN" IN IRON ORE

Three electric cars were set on fire

For this purpose, the researchers have battery modules as well as 3 with them Lithium-ion battery technology fueled and 2 diesel-powered cars and vans set on fire in the test tunnel. In the one from the Austrian Research Promotion Agency FFG supported project BRAFA the methods for fighting fires in electric vehicles were also evaluated, the Graz University of Technology announced in a broadcast on Thursday. Extinguishing attempts were started after a fire time of ten minutes.

The good news after the experimental and numerical studies carried out by experts from Graz University of Technology, the Montanuni Leoben, the Federal Fire Brigade Association and from ILF Consulting Engineers Austria were involved: The hazard potential is not to be assessed much more critically than in the case of fires in cars with conventional internal combustion engines. “Austrian tunnels are fit enough for the challenges that come with burning electric vehicles,” he said Peter Sturm from the Institute for Internal Combustion Engines and Thermodynamics at TU Graz.

When an electric car catches fire, it creates more heat

Those of more than 30 sensors The measured heat release from the burning electric vehicles in the tunnel was included 6 buses 7 MW slightly higher than for diesel-powered comparison vehicles (5 MW). According to the experts, however, this does not entail any new risks or dangers. In comparison, the fire load of a conventional truck is around 30 MW. “When electric vehicles fire, it gets a little hotter in the tunnel, but it is not fundamentally more dangerous. The temperatures measured in the escape area are suitable for all fire tests below the 60 degree Celsius limit. It’s not a pleasant temperature, but escape and fire fighting are still possible, “summarized Sturm.

The gases and heavy metals produced during the fires were collected and measured: Here, above all, the higher amounts of Hydrogen fluoride and Carbon monoxide viewed critically. “However, the thermally induced smoke gas stratification in the tunnel means that these highly concentrated fire gases mainly collect in the upper areas of the tunnel and thus outside of the area relevant to humans. That means the escape routes are not affected,” explained the technician, who himself concerned with air quality in tunnels for more than 30 years.

++ HANDOUT ++ STEIERMARK: BURNING E-CARS - REAL FIRE TRIALS IN "CENTER ON THE MOUNTAIN" IN IRON ORE

Electric car fires in garages are potentially more dangerous

According to Sturm, the ventilation systems have a large share in the comparatively low risk in the road tunnels: “They don’t exist in parking garages, for example, or at least not to the same extent urgently need to be examined more closely. Our measurement results in any case indicate a serious risk potential, “warned the Graz researcher.

According to the experts, the type of drive of the burning vehicle does not make any relevant difference in terms of damage to the structure and materials of the tunnel: Concrete damage due to spalling is to be expected in both vehicle categories in the event of commercial vehicle fires. The damage pattern is roughly the same.

Water worked best when extinguishing

Among the extinguishing methods, fire fighting with water worked best. “However, experience shows that with lithium-ion batteries, an extinguishing success only sets in when the water can reach the inside of the battery,” said Stefan Krausbar from the Austrian Federal Fire Brigade Association. In any case, the duration of extinguishing and the need for extinguishing agents would increase. The use of extinguishing lances has proven to be effective, but the emergency services must be specially trained for this. After use, the extinguishing water was heavily contaminated with heavy metals – especially nickel. This increases the costs of disposal, as Günter Rattei from Asfinag explained.

Project manager Sturm emphasized the importance of further investigations: The fire effects of battery-powered commercial vehicles – buses and trucks – have only been scaled up using numerical simulation based on assumptions about fire development, duration and pollutant release. Comprehensive fire experiments in large-scale trials would therefore significantly improve the quality of the information. The same applies to the specific risk situation in the event of e-vehicle fires in parking garages. “With all the joy about the advance of alternative drive systems, such safety-relevant ‘homework’ must not be neglected”, Sturm appealed to legislation and research funding.

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