New Energy Carriers in Focus at the FIVE and ISTSS Conferences
New energy carriers were in focus for several of the presentations during the FIVE and ISTSS conferences, which were held one after the other in Stavanger in April 2023.
A total of 184 delegates participated in the FIVE conference, the majority from Sweden, and 212 delegates participated in the ISTSS conference, the majority from Norway. Many delegates attended both conferences, which confirms that they should be arranged together in the future. Despite the location of the conferences, about 10% of the delegates were from Asia and another 10% from North America. The program attracted participants from all over the world.
Given below are short summaries of some of the presentations.
Fires in Electric Vehicles
Norway has not only plenty of tunnels, but it is also the country with the most electric cars per inhabitant, now up to 20% of all passenger cars. Kjetil Solberg from DSB, Norway, presented recent statistics on electric cars at FIVE. The statistics show that a fire in a conventional car is about five times as common as a fire in an electric car. Statistics from Tesla and Sweden also indicate that fires in electric vehicles are less likely. In addition, it is rare for fires to start in the traction battery, which is well protected and difficult to ignite in the event of an external fire. This means that a fire in an electric car is not synonymous with a battery fire. According to statistics from the NIPV in the Netherlands, the traction battery was involved in about half of the fire cases in electric cars. Once a thermal runaway has started, it is, as commonly known, difficult to extinguish. P-O Enqvist, representing MSB, Sweden, presented experiments where they penetrated the battery pack and cooled adjacent cells with water, ceasing the thermal runaway.
“The statistics show that a fire in a conventional car is about five times as common as a fire in an electric car.”
Fire extinguishing tests on ro-ro vessels from the LASH FIRE and ELBAS projects were also presented. These showed that traditional water sprinkler or manual fire extinguishing performed equivalently to conventional vehicle extinguishing, which is good news for spaces with fixed water-based firefighting systems, such as those found in tunnels and parking garages.
Rescue Rooms in Norwegian Tunnels
Norway has a special challenge due to its many long single-tube tunnels. In the event of a fire, evacuating can be very difficult as one may need to walk several kilometers to tens of kilometers to reach the tunnel portals. The standard of these tunnels varies from newer to older tunnels, and upgrading all of them to twin-tube tunnels with escape routes is not economically or practically feasible. Sprinkler systems are not commonly installed in Norwegian tunnels. This has led to increased interest in emergency rooms for long single-tube tunnels. According to the EU directive on road tunnel safety, which followed the tragic tunnel fires in the Alps at the turn of the millennium, rescue rooms may not be used. However, Norway has applied for an exemption and is evaluating emergency rooms in three tunnels. In Oslo, “rescue rooms” have already saved lives when evacuees sought refuge between the tunnel tube and the mountain and were then rescued by emergency services. After that, designated rescue rooms were installed in the tunnel. Norway has conducted several research projects on emergency rooms, including using virtual reality (VR) technology to study different rescue room designs.
Sprinklers in Road Tunnels
Sprinklers, or Fixed Fire Fighting Systems (FFFS), in tunnels have seen a resurgence in recent years in countries like the USA and Sweden. Ulf Lundström from the Swedish Transport Administration presented developments in Sweden, where a new type of FFFS has been developed with a large dispersion angle that can cover an entire tunnel cross-section for three-lane motorway tunnels. This allows for a single pipe system along the roof’s centerline, providing a robust and simple solution. It is common to have sectioned systems where all nozzles within an area are activated simultaneously. However, there is also a project investigating automatically activated sprinklers that could use seawater in an underwater tunnel, the Muskö tunnel. By circulating seawater in the pipes, freezing during winter could be avoided, which may also be an alternative for Norwegian fjord tunnels. Several other presentations addressed how the impact of sprinklers can be modeled when fires are simulated in tunnels.
Vehicles Powered by Gaseous Fuel
Several presentations covered the risks associated with gas vehicles. These vehicles use different types of gas, including liquefied gases like LPG or LNG, though most presentations focused on hydrogen and compressed natural gas (CNG) stored at high pressures. The primary risk is the high pressure, ranging from 200 to 700 bar, which can cause a severe pressure vessel explosion if the container ruptures. In the event of a fire, a melt-fuse (TPRD) is supposed to activate and release the gas. However, several explosions involving CNG composite tanks have occurred, possibly due to local fire exposure that failed to reach the TPRD. In these cases, the plastic in the composite melted, reducing the tank’s strength. Such a pressure wave can be fatal within 5-10 meters of the container in open air, but the risk is much greater in a tunnel, where the pressure dissipates slowly, and deflagration of hydrogen gas can increase due to tunnel enclosure. Projectiles also present a significant risk. A proposed solution is explosion-proof tanks that release gas through the fibers when the plastic melts, resulting in microscopic jet flames. These tanks eliminate the worst-case rupture scenario and reduce the risk of jet flames or gas cloud explosions by quickly combusting or diluting the released gas.
Invitation to FIVE and ISTSS 2025
The response from delegates and discussions during the conferences highlighted the importance of such events and the success of holding FIVE and ISTSS during the same week. The next conferences are planned for Reykjavik, Iceland, from April 7-11, 2025, again in conjunction with each other. If you’re interested, you can subscribe to the newsletters below for ongoing information about the conferences, including submission dates for articles. For future conferences, there is a goal to include rescue services to a greater extent, encouraging them to submit articles and conference contributions.
Jonatan Gehandler
jonatan.gehandler@ri.se
For more information, please visit www.ri.se/en.
