Specialist freight insurance provider mutual TT Club, a part of the Thomas Miller Specialty-managed stable, has noted that fire was not the only danger related to lithium-ion batteries. It said that it was seeking greater emphasis on the critical dangers of toxic gas emissions associated with lithium-ion battery fires.
The failure of such batteries has the potential to occur with no prior warning, or with such speed that there is typically no time to react to any warning signs, the Club said.
Devastating consequences of rapidly spreading, and often challenging-to-extinguish, fires involving the batteries, particularly in electric vehicles (EV), on board ships, and other parts of the supply chain have been well-documented in recent months, TT Club said, while noting that there was “less awareness of the highly toxic combustion products that are released and their respective impact to the health and wellbeing of those exposed to the gases”.
Based on the evidence of past fires the time between the initiation of a failed battery igniting to a discharge of toxic vapour could be a matter of seconds rather than minutes, due to thermal runaway. The Club said that thermal runaway typically occurred where an internal electrical short within one of the battery cells generated heat; which breaks down the internal structure of the battery, increasing the rate of the reaction in an ever-increasing cycle. When this happens there was often a dramatic release of energy in the form of heat and a significant emission of toxic gases, TT Club said.
Neil Dalus of TT said that “during a lithium battery thermal runaway event, research has shown that significant amounts of vapour can be produced per kWh (kilowatt hour). In many common supply chain scenarios, including ships’ holds and warehouses, the reality is that such vapour clouds are likely to accumulate. Even when the clouds are able to disperse, the potential toxic effects may occur at lower concentrations.”
He said that what this meant was that drivers, stevedores, ships’ crews and first responders who were attempting to control the blazes would encounter what they might think was smoke, but was in fact a mix of toxic gases, generated quickly and in large volumes.
These gases, once in the atmosphere, behave differently to smoke, often pooling at floor level due to their density. “Traditionally where fires and smoke are concerned one would stay low to avoid inhalation, but doing so where lithium battery fires are concerned is likely to prove problematic,” said Dalus.
He observed that the toxicity of gases given off from any given lithium-ion battery differed from that of a typical fire. All were either poisonous, or combustible, or both. They could feature high percentages of hydrogen, and compounds of hydrogen, including hydrogen fluoride, hydrogen chloride and hydrogen cyanide, as well as carbon monoxide, sulphur dioxide and methane.
In terms of hazards to the wellbeing of those in the vicinity of such an incident, one particularly problematic component was hydrogen fluoride (HF). HF is lighter than air and would disperse when released, a cloud of vapor and aerosol that is heavier than air might be formed (EPA 1993). On exposure to skin or by inhaling, HF can result in skin burns and lung damage that can take time (from hours to weeks) to develop. HF is absorbed rapidly by the body via skin and lungs. This depletes calcium and magnesium levels in tissues, which in turn can result in severe and possibly fatal systemic effects. The hydrogen content of the released gases can give rise to vapour cloud explosion risks which have the potential to cause significant damage.
TT said that it was advocating a range of measures that could be used to mitigate the risks:
- A fire risk assessment, which would consider the specific hazards presented by lithium-ion batteries. providing operatives with certified full-face self-contained breathing apparatus, chemical-resistant boots among other protective equipment
- Drench showers for post-response decontamination.
- Strategic positioning of fire-fighting equipment should also be a key consideration.
Early detection of such an incident could also be pivotal in managing the response, while camera and thermal imaging could enable an expedient response.
Such equipment might have already become commonplace for some modes. However, conducting a thorough risk assessment for example when cargo was stored in warehouses would be prudent, TT Club said.
Dalus commented that “given the hazardous nature of this vapour, if any of these measures are not in place then the best course of action is to evacuate the area and leave the incident response to the emergency services, ensuring that the known risks are appropriately communicated.”
Consideration should also be given to the location of any incident that might include clean up and entry. The gases produced potentially leave toxic deposits on all surfaces and in the atmosphere. Therefore, once the incident is under control, potential hazards remain.