The Australian Maritime Safety Authority (AMSA) has published a new safety alert that aims to raise awareness of the risks involved with the carriage of battery-powered electric vehicles (BEVs) on roll-on, roll-off (Ro-Ro) ferries.
The alert provides guidance to operators of domestic commercial vessels (DCVs) on risks associated with the carriage of BEVs on Ro-Ro ferries, and how best to deal with these risks.
Risk assessment
As per Marine Order 504 (Certificates of operation and operation requirements) operators must conduct a risk assessment for their vessels to ensure that risks arising from the carriage of BEVs are addressed.
Consideration must be given to the hazards arising from transporting BEVs and a vessel specific procedure developed for the prevention and mitigation of fire incidents involving BEVs.
New risks identified in relation to BEVs
Some risks associated with BEV fires onboard DCVs include:
Further considerations
BEVs are approximately 25 per cent heavier than vehicles with internal combustion engines. This should be considered when stowing the vehicles to minimise the potential impact on vessel stability.
Lithium-ion batteries that are used in most battery-powered vehicles have been known to suffer from spontaneous thermal runaway fires. The lower the charge retained by the vehicle's battery, the lower the likelihood of a thermal runaway fire.
Some battery-powered vehicles have a lower ground clearance than internal combustion engine vehicles. This means they are more susceptible to damage from ramps during boarding. Care should be taken in identifying these vehicles before boarding to ensure damage is not sustained to the battery. Physical damage of the battery can lead to thermal runaway. BEVs that have been damaged should not be loaded.
Charging the battery while on board a vessel can increase the likelihood of a thermal runaway fire.
The use of close-circuit television (CCTV) with thermal imaging may allow for early detection of thermal runaway. Also, the crew can use a thermal imaging camera when conducting safety rounds of the vehicle deck to allow for early detection.
Manufacturers estimate that the minimum temperature in the battery where potential exists for thermal runaway to begin is between 60°C and 70°C.
Fumes (hydrogen fluoride) given off by the lithium-ion batteries fires are toxic.
When fighting a lithium-ion battery vehicle fire with water, substantially higher quantities of water are required in comparison to an internal combustion vehicle fire. The water must also be applied for a longer period. There is also an elevated risk of re-ignition. Using other medium such as a car fire blanket designed to extinguish BEV fires may also assist in containing the fire.
A damaged high-voltage battery can create rapid heating of the battery cells. If one notices hissing, whistling, or popping, a possible sweet chemical smell, then black "smoke" (nanoparticles of heavy metals, not smoke) then white vapour coming from the high-voltage battery or the vehicle generally, one must assume that thermal runaway has occurred.
Directly attacking the fire with water hoses and breaking open the battery requires specialist training and equipment. It should not be attempted without extensive training and practice.
Recommendations
AMSA recommends operators of DCVs that carry or are likely to carry BEVs to review their safety management system, in line with the following operational guidance:
The safety alert may be downloaded via this link.