Transport at Nanoscale Interfaces Laboratory
Risk minimisation of electric vehicle fires in underground traffic infrastructures
L. Mellert, U. Welte, M. Tuchschmid, M. Held, M. Hermann, M. Kompatscher, M. Tesson, L. Nachef
Research project AGT 2018/006 petitioned by the Tunnel Research Work-ing Group (Arbeitsgruppe Tunnelforschung, AGT), August 2020
Abstract
Electric vehicle fires with lithium-ion batteries lead to new types of pollutant emissions. The present study shows that this changes the toxicological risks in underground traffic infra-structures because these pollutants do not occur in fires of conventional vehicles. These battery specific contaminations will not impair technical operations in underground car parks or road tunnels; but they will make a careful handling of firefighting and cooling water essential.
The experimental findings were derived using a systematic approach based on scientific principles. The experiment was carried out in the underground facilities of VersuchsStollen Hagerbach AG, which provide a real environment for fire tests related to both underground car parks and road tunnels. Since the present study is based on the experiments of a pre-vious project from 2018, the same test material was used: The experiment focused on maximum damaging a lithium-ion battery (type NMC) used in a battery electric vehicle ap-proved for traffic (status 2019). The analysis of fire residues and their impact on infrastruc-tures was the main focus. Neither fire or crash tests were conducted with full electric vehi-cles nor were there any analyses on the probability of such damages.
The hypothesis that the emissions from electric vehicle fires in underground traffic infra-structures lead to lasting effects cannot be confirmed. The study concludes that a technical impairment of typical infrastructure components in underground car parks and road tunnels can be practically excluded. However, the battery specific emissions will lead to contami-nation which is of toxicological importance especially for decontamination and disposal works. Based on the findings, six risk-reducing measures can be derived, which are pri-marily of an organisational nature; two of them are urgent.
Firefighting and cooling water resulting from an electric vehicle fire is highly contaminated. Since the concentrations of lithium and the heavy metals cobalt, nickel and manganese exceed current thresholds for discharge into the sewerage system many times over, ap-propriate pre-treatment must be implemented in practice. The application of the current principles for NBC operations is sufficient for this purpose. Regarding the cooling water which is typically produced in the after-treatment of damaged batteries, a standardised handling needs to be defined. The other recommendations include additional preventive measures that allow an appropriate handling of the changing risk landscape.
Concerning electric mobility in underground infrastructures, two aspects are in the fore-ground that should be investigated in greater depth: (I) The effectiveness of high-pressure water mist systems, which are used internationally, especially under the argument of new energy carriers. Since these systems are hardly or not at all used in underground infra-structures in Switzerland, they should be reassessed in the course of the increasing use of lithium-ion storage systems. (II) On the other hand, the risks of fuel cell electric vehicles, especially in the case of heavy goods vehicles in underground infrastructures, are still not clear. A risk assessment with experimental methods seems to be recommendable.
Lithium-ion storage systems lead to changed risks, not only in mobile applications. Station-ary storage systems of buildings are based on the same technology and are increasingly installed in basements where the operational and safety situation is similar. The specific risks, particularly the potential severity, are largely unclear and should also be investigated experimentally.
The experimental findings were derived using a systematic approach based on scientific principles. The experiment was carried out in the underground facilities of VersuchsStollen Hagerbach AG, which provide a real environment for fire tests related to both underground car parks and road tunnels. Since the present study is based on the experiments of a pre-vious project from 2018, the same test material was used: The experiment focused on maximum damaging a lithium-ion battery (type NMC) used in a battery electric vehicle ap-proved for traffic (status 2019). The analysis of fire residues and their impact on infrastruc-tures was the main focus. Neither fire or crash tests were conducted with full electric vehi-cles nor were there any analyses on the probability of such damages.
The hypothesis that the emissions from electric vehicle fires in underground traffic infra-structures lead to lasting effects cannot be confirmed. The study concludes that a technical impairment of typical infrastructure components in underground car parks and road tunnels can be practically excluded. However, the battery specific emissions will lead to contami-nation which is of toxicological importance especially for decontamination and disposal works. Based on the findings, six risk-reducing measures can be derived, which are pri-marily of an organisational nature; two of them are urgent.
Firefighting and cooling water resulting from an electric vehicle fire is highly contaminated. Since the concentrations of lithium and the heavy metals cobalt, nickel and manganese exceed current thresholds for discharge into the sewerage system many times over, ap-propriate pre-treatment must be implemented in practice. The application of the current principles for NBC operations is sufficient for this purpose. Regarding the cooling water which is typically produced in the after-treatment of damaged batteries, a standardised handling needs to be defined. The other recommendations include additional preventive measures that allow an appropriate handling of the changing risk landscape.
Concerning electric mobility in underground infrastructures, two aspects are in the fore-ground that should be investigated in greater depth: (I) The effectiveness of high-pressure water mist systems, which are used internationally, especially under the argument of new energy carriers. Since these systems are hardly or not at all used in underground infra-structures in Switzerland, they should be reassessed in the course of the increasing use of lithium-ion storage systems. (II) On the other hand, the risks of fuel cell electric vehicles, especially in the case of heavy goods vehicles in underground infrastructures, are still not clear. A risk assessment with experimental methods seems to be recommendable.
Lithium-ion storage systems lead to changed risks, not only in mobile applications. Station-ary storage systems of buildings are based on the same technology and are increasingly installed in basements where the operational and safety situation is similar. The specific risks, particularly the potential severity, are largely unclear and should also be investigated experimentally.