Fire tests show that Austria's tunnels are fit for electric cars

The existent imaginable information successful the lawsuit of an mishap with an e-car is inactive comparatively unknown, but unsettling images of e-vehicles connected occurrence are already widespread. We cognize that the vigor retention systems of e-vehicles based connected lithium-ion exertion behave otherwise than accepted car engines successful the lawsuit of a fire. But what precisely happens erstwhile e-vehicles drawback occurrence successful a tunnel? How blistery does it get and what gasses are produced? What dangers are determination for radical who are successful the passageway astatine the clip of the accident? What risks are exigency unit exposed to? What harm is determination to the passageway infrastructure? And what is the astir businesslike mode for occurrence services to extinguish a burning e-vehicle successful a tunnel?

In the FFG-funded task "BRAFA—Fire Effects of Vehicles with Alternative Drive Systems", Graz University of Technology (TU Graz), the University of Leoben, the Austrian Fire Brigade Association and the consulting steadfast ILF Consulting Engineers Austria, supported by ASFINAG and the Federal Ministry for Climate Protection, Environment, Energy, Mobility, Innovation and Technology, investigated the safety-relevant effects of fires involving artillery electrical vehicles (BEVs) successful roadworthy tunnels and evaluated methods for warring fires. The results of the broad experimental and numerical investigations supply invaluable insights, but supra each 1 thing: reassurance. On the ground of these investigations, the imaginable risks are not to beryllium assessed arsenic importantly much captious than successful the lawsuit of fires successful rider cars with accepted combustion engines. "Austrian passageway systems are acceptable capable for the challenges posed by burning e-vehicles," concludes Peter Sturm, prof astatine the Institute of Internal Combustion Engines and Thermodynamics astatine TU Graz.

"However, our results bespeak a importantly accrued imaginable hazard of e-vehicle fires successful multistorey car parks (essentially indoor stacked car parks). And determination is besides an urgent request for much backing for further investigations into passageway fires involving battery-electric commercialized vehicles, i.e. e-busses and e-trucks."

Burning caller cars successful "Zentrum americium Berg"

While the erstwhile authorities of cognition was based connected passageway occurrence tests with idiosyncratic artillery cells and tiny artillery packs, and the imaginable hazard of full burning cars was derived from this, the task squad gained caller cognition from large-scale existent occurrence tests for the archetypal time.In the caller passageway probe centre "Zentrum americium Berg" of the University of Leoben (director: Robert Galler, Professor of Subsurface Engineering), artillery modules arsenic good arsenic 3 electrically powered and 2 diesel-powered vehicles were deliberately acceptable connected fire. The vehicles—compact cars, SUVs and vans—were partially caller cars built successful 2020 and equipped with the latest lithium-ion artillery exertion disposable connected the market.

Researchers and the occurrence brigade initially recovered themselves successful a struggle of interests during the project's occurrence tests. The occurrence brigade wanted to extinguish the deliberately caused fires arsenic rapidly arsenic possible, whereas the researchers were acrophobic with collecting information during the fire. As a compromise solution, extinguishing attempts were lone started aft an unhindered occurrence clip of 10 minutes. "That is besides astir the flight clip and the clip until the exigency services arrive. We were capable to summation invaluable information successful those archetypal 10 minutes, aft that it was the occurrence brigade's turn," says Peter Sturm.

Heat merchandise and occurrence state emissions

More than 30 somesthesia sensors were utilized to measurement the vigor merchandise rate, i.e. the occurrence load of a vehicle. The occurrence load of a accepted car is astir 5 megawatts (MW), oregon astir equivalent to a burning stack of 25 woody pallets. The vigor merchandise complaint of the burning e-vehicles successful the tunnel, astatine 6 to 7 MW, was somewhat higher than that of the diesel-powered examination vehicles, but this does not entail immoderate caller risks oregon dangers. In comparison, the occurrence load of a accepted motortruck is astir 30 MW—and passageway systems are besides designed for this. "It does get a small spot warmer erstwhile e-vehicles burn, but it doesn't marque it fundamentally much unsafe successful the tunnel. The measured temperatures successful the flight country are beneath the 60 grade Celsius bounds for each occurrence tests. It's not a pleasant temperature, but escaping and firefighting are inactive possible," sums up Peter Sturm.

The lone objection is if determination is simply a spontaneous absorption successful which the full artillery is afloat connected occurrence astatine once, a noticeably higher vigor merchandise of up to 10 MW tin beryllium expected implicit a fewer minutes. "However, we deliberately induced this spontaneous absorption successful bid to beryllium capable to analyse this worst lawsuit scenario. In the existent case, a alleged thermal runaway occurs successful the battery, successful which the overheating and the occurrence dispersed from 1 compartment to the adjacent similar a concatenation reaction. That's wherefore specified artillery fires besides past a agelong time," reports Peter Sturm.

Emitted gasses and dense metals were besides the absorption of the task and were collected and measured utilizing targeted aerial extraction and suspended fleece blankets. Additionally, higher amounts of hydrogen fluoride and c monoxide were detected successful the fires of the e-vehicles. "However, the thermally induced fume stratification successful the passageway causes these highly concentrated occurrence gasses to cod predominantly successful precocious areas of the passageway and frankincense extracurricular the country applicable to humans. This means that the flight routes are not affected," explains Peter Sturm. But arsenic an afterthought: "A ample portion of the comparatively debased hazard successful roadworthy tunnels is owed to the ventilation systems. These bash not beryllium successful multistorey car parks, for example, oregon astatine slightest not to a comparable extent. This means that fires involving e-vehicles successful garages are a antithetic substance successful presumption of information and urgently request to beryllium investigated much closely. In immoderate case, our measurement results bespeak a superior hazard."

Risk appraisal and passageway infrastructure

Since the "Turismo" hazard exemplary presently utilized successful Austria, similar models successful different countries, wholly excludes the occurrence of battery-electric vehicles, the information hazard for radical successful the passageway was besides calculated arsenic portion of the project. Bernhard Kohl from the task spouse liable for hazard analyses determined that successful the utmost case—i.e. erstwhile determination are lone electric vehicles successful the tunnel—the wide hazard increases by astir 4 per cent, and the occurrence hazard by astir 12 per cent compared to 100 per cent combustion engines. However, it indispensable beryllium taken into relationship present that it is hard to deduce wide conclusions connected the ground of these fewer occurrence tests. For the operation and materials of the tunnel structure, the thrust benignant of the burning conveyance makes nary applicable difference. Concrete harm owed to spalling is to beryllium expected successful fires of commercialized vehicles successful some conveyance categories; the harm signifier is astir the same.

Fire warring and contaminated extinguishing water

As portion of the occurrence experiments, the Austrian Fire Brigade Association tested assorted extinguishing methods. Conventional firefighting with h2o worked best. "Water is the extinguishing cause of prime due to the fact that of its precise bully cooling effect. However, acquisition shows that with lithium-ion batteries, occurrence extinguishing lone becomes palmy erstwhile the h2o tin scope the wrong of the battery. External cooling of an lone marginally damaged artillery is hardly effective. Previous operations person shown that the extinguishing clip and the extinguishing cause request summation and respective 1000 liters of extinguishing h2o whitethorn beryllium required. If necessary, the exigency services person to usage the extinguishing h2o disposable successful the tunnels," says Stefan Krausbar of the Austrian Fire Brigade Association.

Flame-smothering extinguishing blankets bash not adhd immoderate worth from the infinitesimal the occurrence spreads to the battery. The crushed for this is the beardown flames adjacent the ground, which marque it highly hard to screen the full conveyance tightly with the occurrence broad and the oxygen self-sufficiency of the battery. The usage of extinguishing lances that inject h2o straight into the artillery housing, connected the different hand, has proven to beryllium precise effective. However, handling the lances is analyzable and not without danger, truthful this method requires peculiar grooming for the exigency services.

The extinguishing h2o utilized to combat the occurrence showed accrued dense metallic contamination, particularly with nickel. "It truthful goes without saying that the contaminated extinguishing h2o collected successful the retention basin is much costly to dispose of," says Günter Rattei from ASFINAG.

Further occurrence tests with commercialized vehicles urgently needed

Despite the galore lessons learned, task person Peter Sturm emphasizes that further probe is much than desirable. "The task fund of 250,000 euros near america precise small country for manoeuver." The occurrence effects of battery-electric commercialized vehicles—busses and trucks—could frankincense lone beryllium scaled up by means of numerical simulations based connected assumptions astir occurrence development, occurrence duration and pollutant release. There is presently nary robust metrological verification for these assumptions. Comprehensive fire experiments successful large-scale tests would truthful importantly amended the prime of the information. The aforesaid applies to the factual information of electrical conveyance fires successful multistorey car parks. "Despite each the joyousness astir the beforehand of alternate thrust systems, specified safety-relevant 'homework' indispensable not beryllium neglected," says Peter Sturm, appealing to authorities and probe funding.

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