Risks related to new energy carriers
While new energy carriers (NEC) do not necessarily increase risks in general, they can generate new hazardous phenomena, particularly in underground environments, which must be understood, prevented and dealt with as effectively as possible. CETU has been involved in studying these phenomena for several years and launched a dedicated strategic research programme in 2022.
Context
It is clear that our mobility is currently undergoing a major change, in an attempt to combat global warming, air pollution and noise, that are are all caused by road traffic and that new forms of mobility can help to reduce.
Whilst there is a need to limit motorized traffic in favour of other modes of transport, it is also important to make the vehicles that will continue to be used cleaner, whether they are goods vehicles, public transport or private cars. For light vehicles and local goods transport, there is a shift towards widespread electrification of the fleet. Hydrogen is expected to replace diesel for long-distance transport, as well as for certain public transport services. Natural gas is already well established as a transitional energy source in public transport and other urban fleets (delivery, waste collection purposes). The transition is also beginning in rail transport, with hydrogen trains expected to replace some diesel trains in several regions as of 2025.
Risks associated with new energy carriers (NEC)
The risk of fire is already present in tunnels and for many years has been the focus of significant research efforts, tunnel equipment upgrades and organisational changes by operators and emergency services. New energy carriers do not necessarily increase risks in general, but they can generate new hazards, particularly in underground environments, which must be understood, prevented and dealt with as effectively as possible.
Battery fires are no more powerful than the petrol vehicle fires we are familiar with, but they can pose difficulties for the emergency services trying to extinguish them, and therefore for the operator who needs to reopen the tunnel to traffic as soon as possible. Battery technologies are varied and rapidly evolving, and attention must be paid to the associated risks. Compressed or liquefied gases can cause explosions in the event of a leak or failure of safety systems.
CETU’s research activities on this topic
CETU has been involved in studying these phenomena for several years and significantly increased its efforts in 2022 with the launch of a dedicated strategic research programme. This programme addresses various aspects of the issues involved.
The ‘New Energies and Technological Risks in Tunnels’ (NERTT) working group, led by CETU, brings together operators, transport authorities, emergency services and technical experts. Its aim is to establish a common understanding of the risks, as well as the legal and practical constraints faced by each party.
Independent and collaborative research aims to improve our understanding of the triggers and consequences of explosive phenomena related to compressed or liquefied gases (natural gas and hydrogen). In particular, we are seeking to understand which parameters, related to the vehicle or the tunnel, influence the scale of events, and how best to assess their consequences for users, emergency services and structures.
In partnership with numerous design offices, work has also begun on establishing a method for taking these new phenomena into account in risk analyses, and more particularly in specific hazard identification studies.
The rail sector is not to be excluded. CETU has co-led a working group with EPSF (the French authority on rail safety) to analyse the potential risks associated with hydrogen trains, and is contributing its expertise to the knowledge of NEC in this field.
At the international level, CETU is involved in the PIARC working group dedicated to new energies in road tunnels, and regularly speaks on the subject at conferences and symposiums (ISAVFT, Interflam, ITACET, ITA-COSUF, etc.).
Bibliographical references:
WILLMANN (C.), TRUCHOT (B.), New Energy Carriers and Additional Risks for User Safety in Tunnels, INTERFLAM 2019, London, 1-3 July 2019, pp. 1833-1844
WILLMANN (C.), TRUCHOT (B.), User’s safety in tunnels - additional risks of new energy carriers vehicles, 8th ISAVFT, Athens, 25-27 September 2019, pp. 450-464
PIARC, Impact of new propulsion technologies on the operation and safety of road tunnels – Case studies, 2022, 46p.
CETU, Nouveaux modes de propulsion en tunnel routier : risques et enjeux, shortly available in English.