IFSJ Exclusive: Reducing fire risks for EVs and HEVs

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Jonas Bergström, business manager, Dafo Vehicle Fire Protection, bus and coach division, looks at new fire risks for EVs and HEVs and how can we reduce them

Countries around the world are pledging to reach ambitious climate change targets, and ensuring net-zero emissions is a huge part of this. As a result, we’re seeing a sustained transition to renewable fuel sources in various industries, and the automotive industry is one of those changing, so it can meet the growing demand for electric public transport.

Jonas Bergström, Business Manager for Dafo Vehicle Fire Protection’s bus and coach division explores the various vehicle fire risks in the bus industry as a result of increased electrification and discusses how operators can reduce rising risks.

Changes in European regulations

The United Nations Economic Commission (UNECE) recently enacted Regulation 107 to reduce the fire risks associated with combustion engine buses and coaches and make them safer. This regulation makes it mandatory for combustion engine vehicles to install an automated fire suppression system within the vehicle’s engine compartment.

However, this new regulation doesn’t address the fire hazards in electric vehicles (EVs). For hybrid electric vehicles (HEVs), the combustion engine may be covered by the UNECE’s new regulation, however, it does not protect the lithium-ion (li-ion) battery making up the vehicle’s electrical component.

UNECE Regulation 100 (Construction and Safety of Electric Powertrains) also published its latest draft, outlining a proposal recommending early warning systems for battery failure/damage that may cause a fire. It outlines that, when there’s a risk of thermal runaway, a vehicle’s detection system should provide an early warning signal. Therefore, to recognise battery failure at its earliest possible stage to prevent ignition, a fire suppression system will need to recognise when thermal runaway could take place and how to prevent it.

New fire risks and how to identify them

Li-ion batteries, which power the majority of EVs and HEVs, are at risk of thermal runaway. This can take place following a defect in a battery’s cells – which could be caused by overcharging, overheating, overvoltage or physical damage – and may lead to rapid temperature increases that can cause fire, toxic gas emissions and potential explosions. This type of fire is an increasing risk to life and vehicles, and traditional systems are often not able to extinguish thermal runaway effectively.

Research into thermal runway has found that to extinguish these types of fire effectively, suppression systems have to apply huge amounts of water for an extended period of time. However, this is often impractical, as damaged electric buses will likely need to be moved and stored elsewhere to reduce risks. An early fire warning system and spot cooling is often a more suitable alternative method, which prevents thermal runaway before it takes place.

As EVs and HEVs are introduced into the public transport industry, there are various challenges that need to be overcome and risk assessments that need to be put in place. For example, the location of fire risks in traditional combustion engine vehicles and EVs differ. Combustion vehicles are often only at risk within the engine compartment, whereas, as we move to electric, you’ll need to protect additional zones throughout the vehicle.

The Research Institutes of Sweden (RISE) issued assessments for fire-risk management to be used as a guideline:

  1. Identify hazards
  2. Estimate risks
  3. Evaluate risks
  4. Reduce risks.

These steps should include failure mode and effective analysis (FMEA) to identify hazards and quantify risks, so you can rank them according to their priority. After risks are quantified and prioritised, they can provide a holistic view of the site in a risk map. This will separate any risks that are acceptable from those that need to be addressed.

Finally, you should create an action plan for fire risks that are identified with adequate risk reduction measures, including:

  1. Eliminating or minimising risk by design
  2. Active or passive protection systems
  3. Improving cleaning or maintenance procedures
  4. Improved quality of training procedures.

Once the hazards have been identified, your priorities will naturally emerge, allowing you to understand which risks need to be addressed first.

To find out more about how to choose your bus or coach’s fire protection solution, visit Dafo Vehicle Fire Protection.

This article was originally published in the January edition of IFSJ. To read your FREE digital copy, click here.

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