To achieve the 2050 net-zero transition goal and effectively promote a zero-carbon energy system, the international community has recently placed increasing emphasis on the development of electric vehicles. Governments around the world have also stepped up subsidies for the electric vehicle market and provided related tax incentives. The United States even passed the Inflation Reduction Act of 2022 in August 2022, promising to increase subsidies for electric vehicles. This move has also led to a rapid increase in private demand for electric vehicles in the United States.
However, as electric vehicles are booming, more and more fire departments around the world have noticed that electric vehicles are not only difficult to extinguish after an accidental fire, but firefighters often need to use more water than traditional fuel vehicles to control the fire. How to effectively extinguish fires caused by electric vehicles seems to have become an issue that fire departments are paying more and more attention to.
Canadian news channel CTV News pointed out that firefighters need to use an average of 40 times more water than ordinary fuel vehicles to extinguish electric vehicle fires. Each fire uses up to 40,000 gallons (about 151,400 liters) of water, and fire trucks are usually unable to carry such a large amount of water. If there are no sufficient water sources or fire hydrants at the fire site, electric vehicles may burn for several days before being extinguished.
"Electric vehicle fires in areas where firefighting equipment is scarce are definitely a challenge for us, which is why fire departments are now developing new technologies to combat electric vehicle fires," said Bill Hunter, fire chief and fire educator in Perth County, Ontario, Canada.
Thayer Smith, chief of the Austin Fire Department in Austin, Texas, expressed a similar view in an interview with The Independent. He emphasized that a typical gasoline vehicle fire requires 500 to 1,000 gallons (1,892 to 3,785 liters) of water to extinguish. However, if an electric vehicle's lithium-ion battery begins to burn, 30,000 to 40,000 gallons (113,500 liters) of water may be required to extinguish the fire, and sometimes even more.
Why is it so difficult to extinguish a fire caused by an electric vehicle?
In an exclusive interview with Julie Chang, host of the Wall Street Journal's "Tech News Briefing" podcast, John Keilman of The Wall Street Journal stated that electric vehicles primarily store energy through lithium ions within lithium batteries. However, lithium is a highly reactive metal element. Once a lithium battery is penetrated by foreign objects or experiences a short circuit due to a system failure, it is very likely to cause thermal runaway without any chemical reaction.
Thermal runaway can have devastating consequences for lithium-ion batteries and vehicles. Rapid heating of lithium-ion batteries can lead to fire, and the combustion of plastics and metals can produce toxic gases such as hydrogen fluoride and hydrogen chloride. Sustained thermal runaway can also release large amounts of flammable gases, increasing the risk of steam explosions in electric vehicles. Once an electric vehicle explodes, a jet-like, highly directional flame will appear, burning intensely for a long time.
The Guardian stated that electric vehicle fires not only require large amounts of water and are difficult to extinguish, but also because lithium batteries experience persistent thermal runaway during exothermic reactions, there is a risk of a fire appearing to be under control only to heat up again and reignite. This makes it more difficult for firefighters to handle electric vehicle fires.
The Wall Street Journal also reminds that all electric vehicle drivers should pay attention to the information displayed by the sensors in the car. If any abnormality is found, they should stop driving immediately and report the problem. They should not continue driving after the engine fault warning light is on, as many fuel vehicle drivers do. Even if an electric vehicle catches fire, they should not extinguish it by themselves. Remember, this is not a fire that can be easily extinguished with a traditional fire extinguisher.
Are electric cars more likely to catch fire than gasoline-powered cars?
The Guardian pointed out that although the risk of electric vehicle lithium batteries causing fires is greater than that of fuel vehicles, according to current statistics from various circles, the possibility of electric vehicles causing fires is significantly lower than traditional gasoline or diesel vehicles.
"All the data we've collected shows that electric cars are much less likely to catch fire than gasoline cars, and many gasoline car fires go unrecorded," said Colin Walker, head of transport at the Energy and Climate Intelligence Unit (ECIU), a British think tank.
According to statistics from the Swedish Civil Emergency Response Agency (MSB) in 2022, cited by The Guardian, an average of 3.8 fires occurred for every 100,000 electric or hybrid vehicles, while as many as 68 fires occurred for every 100,000 fuel vehicles.
The newspaper also noted that in Norway, the country with the highest electric vehicle sales globally, fires involving gasoline and diesel vehicles are four to five times more common than those involving electric vehicles. Tesla, the largest electric vehicle company in the United States, also emphasized that the number of fires involving gasoline and diesel vehicles in the United States between 2012 and 2021 was 11 times higher than that of Tesla electric vehicles.
In addition, according to a survey by EV Fire Safe, an electric vehicle fire protection agency funded by the Australian Department of Defense, the probability of a fire occurring while riding in an electric vehicle is 0.0012%, while the chance of a fire starting in a fuel vehicle is as high as 0.1%.
How do firefighters handle fires spread from electric vehicles?
Wall Street Journal reporter Kelman explained that most fire departments in the United States are still trying to find the most effective way to deal with electric vehicle fires. Although many firefighters still resort to spraying large amounts of water on burning electric vehicles, relevant units have now discovered more efficient fire-fighting methods. For example, extending the nozzle of the fire water column to the bottom of the electric vehicle to spray water can improve fire-fighting efficiency because this is usually where the lithium batteries are stored.
Some fire departments have also found that directly wrapping a fire blanket on a burning electric vehicle can shorten the burning time. Another option is to hang the vehicle in a large container mixed with water, sand, and gravel. This strategy can prevent the fire from spreading to the surrounding area and can also block the burning vehicle from contact with oxygen, thereby shortening the burning time.
When technology news briefing host Julie Chang asked whether automakers and electric vehicle companies also need to pay attention to the difficulty of extinguishing electric vehicle fires, Kelman said that many automakers are currently researching related technologies and hope to have the opportunity to eliminate the difficulty of extinguishing electric vehicle fires in the future.
For example, most electric vehicles currently use liquid lithium batteries as their power source. However, liquid lithium batteries are flammable, posing the risk of fire, explosion, or re-ignition due to leakage or improper charging. Consequently, automakers are currently developing solid-state batteries that are less flammable and offer greater stability. Once the technology matures, it has the potential to offer advantages over liquid lithium batteries, including longer driving range and faster charging.
Kelman further noted that some automakers are developing new battery systems that aim to shut down operating systems in the event of an electric vehicle power failure, thereby reducing the risk of spontaneous combustion. German automaker Audi reportedly applied for a battery patent in 2022. If the control system of the brand's electric vehicles detects an imminent risk of spontaneous combustion, it will immediately inject a fire extinguishing agent built into the vehicle's battery system. Audi claims this design can extinguish fires in the shortest possible time, minimizing the cost of firefighting for firefighters.
This article is reprinted with permission from Critical Commentary. The original title is "Firefighting Water Uses 40 Times More! Why Are Electric Vehicle Fires More Difficult to Extinguish Than Fuel-Powered Vehicles?" This article is not licensed under the CC license.
References：
*The Wall Street Journal（2023年11月13日），Firefighters vs. EVs: Why EV Fires Are Harder to Put Out
*The Guardian（2023年11月20日），Do electric cars pose a greater fire risk than petrol or diesel vehicles?
*The Independent（2021年8月12日），Tesla in fireball crash needs 40 times the water as regular car to put out flames, says fire crew
*CTV News（2023年12月20日），Fire officials raise concerns over EV fires
*EV Fire Safe，Risks with EV battery fire
Source: Environmental Information Centre
