(ORDO NEWS) — It can be extremely difficult for firefighters to extinguish large flames. And that’s why.
At 11:30 pm on Saturday, April 17, near Houston (USA), a 2019 Tesla Model S ran onto the road and collided with a tree.
The media reported that, at the time of the accident, no one seemed to be driving the electric vehicle. The bodies of the two men were inside, one in the passenger seat and the other in the back seat of the car, suggesting they were using self-driving autopilot.
Another interesting fact was noted in the reports: when rescuers arrived and tried to put out the fire, it continued to flare up, burning continuously for more than four hours, despite the use of almost 30,000 gallons of water to extinguish it.
It has long been known that high-voltage lithium-ion batteries used in electric vehicles can be dangerous. The fact is that almost all lithium-ion batteries can explode or burn. Five years ago, Samsung had to recall about a million of its new Galaxy Note 7 phones because some of them overheated or caught fire.
In 2016, Amazon was found to be selling defective batteries that sometimes caught fire as well. However, the problem with electric vehicle (EV) batteries is that they contain much more stored energy than a cell phone battery.
“A battery in a Tesla is made up of a lot of individual cells,” says retired research professor at the Center for Renewable Energy Technology K.M. Abraham.
“Under normal conditions, they are safe. But if you short a cell, energy is released in a very short time.
It was a pretty serious accident, and thousands of cells probably burned out at the same time, which generated a lot of heat.”
In one incident in Los Angeles in 2018, a Tesla Model S caught fire while stuck in traffic. Fire erupted from a flat tire. In a statement, Tesla called it “an extremely unusual phenomenon.”
Citing data from the US Federal Highway Administration, Tesla claims that gasoline-powered vehicles are about 11 times more likely to catch fire than one of its own vehicles.
The company uses a metric of “fires per 1 billion miles driven” and says that between 2012 and 2020, there was roughly one vehicle fire for every 205 million miles driven.
Experts agree that electric vehicles catch fire less frequently than gasoline-powered vehicles, but the duration and intensity of fires due to the introduction of lithium-ion battery systems can make firefighting in electric vehicles much more difficult.
“There is a lot of energy stored inside an EV battery and it needs to be extracted in a controlled way,” says Abraham.
“When it doesn’t, you can get a very flammable reaction. It’s like what happens in hell, if you can imagine what happens in hell.”
Abraham explained that water, if used sparingly, could actually exacerbate a lithium battery fire by acting as a conductor. This requires either large amounts of water, or even powdered graphite, which most fire departments don’t have on hand.
Tesla has released a guide to emergency services to help firefighters better deal with battery fires in their vehicles, and its official guide for the Model 3, for example, includes using “large amounts of water”, carbon dioxide, or “dry chemicals” and it warns against “using foam.”
The battery in the Tesla Model S contains 7104 lithium-ion battery cells in 16 modules. Each cell consists of an anode, cathode, separator and liquid electrolyte. The anode and cathode store the lithium, while the electrolyte carries trillions of charged lithium ions back and forth through the separator.
But the liquid electrolyte is highly flammable, and when a lithium-ion battery is exposed to extreme heat or severely damaged in an accident, the result can be an internal short circuit, leading to a phenomenon called thermal runaway.
In essence, it is an uncontrolled cascading loop of violent chemical reactions that releases a huge amount of energy. According to a 2020 NTSB study on electric vehicle fires, most incidents are caused by thermal discharge from a damaged battery.
An innovation that scientists say could improve lithium batteries by making them almost as safe as the AA batteries in your flashlight is solid-state electrolyte.
One company that claims to be developing such a battery is QuantumScape in Silicon Valley. However, the firm is constantly hiding its battery, releasing only limited data and not yet releasing a commercial product.
Some remain skeptical that the technology will live up to its promises.
Experts say more research and testing is needed to find better, less flammable materials, as well as new engineering advances that can reduce the rapid spread of a thermal reaction.
“Lithium-ion technology is still relatively new,” says Joshua Lamb, principal investigator at Sandia National Laboratories’ battery testing lab.
“What we don’t have in battery technology is over 100 years of working with them to know exactly what the dangers are.”
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