Johan Balstad, vice president, Dafo Vehicle Fire Protection, considers the new risks arising from the increased uptake of EVs

In an increasingly environmentally conscious world, the number of electric vehicles (EVs) is growing, meaning it’s time for recognition and understanding of how to mitigate the unique fire risks they pose.

A sustainable future

The number of EVs in use has been rapidly increasing, at 40% year and year, reflecting sustainability by encouraging better air quality, in addition to offering lower fuel costs by reducing the reliance on fossil fuels. This growth is only set to increase further, with improved battery technology and affordability supporting the shift for individuals, and EVs providing certain industries with cost effective, environmental solutions.

Moving forward, battery manufacturers are looking to improve the battery efficiency to cost ratio, in the hope of increasing adoption across the world. It’s predicted that battery technology is likely to increase the amount of energy density within the battery, as well as bringing about faster charging, to improve the consumer experience.

Rising risks

However, although EVs with higher energy density and reduced charging time are desirable, this can increase already rising the fire risks that EVs present.

Although much safer for the environment, EVs present their own unique fire risks that need to be understood in order to be effectively mitigated. Fires in these vehicles are less likely to occur than internal combustion engine (ICE) vehicles, however, due to the chemistry of the battery and the type of fire that can occur, they present more intense fire risks, which can be catastrophic for passengers and operations.

There have been various reports of EV fires causing safety concerns to life and operations. For example, a crash turned fire, which killed three passengers in China and the destruction of 25 EV buses in a bus depot in Germany.

More recently, an EV bus caught fire in Paris, with the cause of the fire unknown and the reasoning for the successful evacuation attributed to passers-by, rather than a fire detection system.

Battery chemistry

The most common battery powering the shift to EVs is the lithium-ion (li-ion) battery, and it’s the chemistry within these batteries that’s causing rising fire risks.

Within the li-ion battery, there is a cathode covered in a sliver of aluminium and mixed-metal oxide ink and an anode covered in copper coated in graphite. Between these poles is a plastic separator in solvent, and during charge or discharge, lithium ions will move from or to the anode or cathode.

Should li-ion batteries experience increased heat, mechanical failure, overcharging or physical damage, this can cause the battery to short circuit. A short circuit will create excess heat, leading to a dangerous state called thermal runaway due to a reaction between the cathode and the flammable electrolyte within the battery.

Reducing fire risks

With EVs being picked up in almost every industry in the near future, there’s a necessity to understand the risks and how industries can protect against them.

1. Equipment

Installing a fire detection and suppression system that is able to recognise that the battery is at risk of thermal runaway in its earliest stage can help to reduce the likelihood of extreme consequences to life and operations.

• Battery management

Battery management systems are great for monitoring temperature, voltage and current in a li-ion battery. However, they can’t prevent thermal runaway should it occur suddenly, such as from a damaged battery due to a crash, for example.

• Educating users

To prevent the catastrophic consequences of a li-ion battery fire, it’s important to educate all of those using an EV on its potential risks. By educating people on the ‘dos and don’ts’ of EV battery safety, fires are less likely to occur due to overcharging, poor management or insufficient suppression measures.

Detection and suppression

If thermal runaway is allowed to fully take hold, reignition is extremely common, and EV fires can burn for days, reigniting after the fire seems to have been defeated. Currently, the only way to make sure a fire is out completely, is total immersion within a pool of water.

This makes early detection and suppression key to reducing fire risk. Extensive research and testing from an EU-funded initiative, in collaboration with Research Institutes of Sweden (RISE) and Dafo Vehicle Fire Protection, found that a battery suppression solution can be installed during the manufacturing process to provide an early fire warning system, in addition to spot cooling to prevent a battery reaching thermal runaway.

During this research, spot cooling was found to be the most effective technique to suppress thermal runaway following the detection of defects. Spot cooling should use a suitable suppression agent. Although fluorine foams have been used for years in fire-fighting due to their suitability, modern environmental concerns have led to bans on suppression agents containing fluorine, which are spreading across the globe.

Moving forward with EV safety

With the increase of EVs happening across almost every industry around the world, it’s important to fully understand fire risks. In addition to managing batteries and educating those about battery safety, installing appropriate fire suppression solutions is key to reduce risks and ensure a safe and sustainable future.

For more information, visit Dafo Vehicle Fire Protection.

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