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points by ortusdux 1 day ago | 0 comments

Are battery fires like this more damaging to the road surface vs a diesel fire?

Depends on context and the location of the road surface and the nature of the explosion.

https://www.sfgate.com/bayarea/article/Tanker-fire-destroys-...

(Also, the rebuilding was epic, the only time I've seen the state and a contractor move quickly: https://longreads.com/2024/07/15/rebuilding-the-maze/ )

[–] driverdan 1 day ago

That's gasoline. Diesel doesn't explode.

[–] dekhn 1 day ago

I interpreted the question more broadly, replacing "diesel" with "fuel".

[–] paxy 1 day ago

Regular cars usually burn out in 30 mins or less. It's a fair assumption that a 10-15 hour fire would be more damaging.

[–] mingus88 1 day ago

I’d think it really depends on the heat and proximity to the road

If a battery pack burn less hot and sits higher off the roadway, I can see it being less damaging

[–] ggreer 1 day ago

I'm not sure, but diesel fires are definitely more of a risk to people. Fuel can quickly spread and ignite before people in the vehicle (or bystanders) have a chance to escape. Lithium battery fires are more contained because individual cells spew flame, which heats up nearby cells, which then undergo thermal runaway. This means that battery fires take longer to release their energy, which is annoying for extinguishing them, but good for anyone who needs to get out of the wreck.

[–] leonidasrup 1 day ago

There is a big difference between diesel powered engines and petrol powered engines. Diesel is much harder to ignite and this was for example big advantage for diesel powered tanks during World War II, in comparison to gasoline powered tanks.

"They introduced many innovations as they built their designs, including bell crank suspensions, as pioneers in amphibious tanks, and the use of diesel engines that were less likely to catch fire compared with gasoline tank engines that were being used at the time."

https://en.wikipedia.org/wiki/Tanks_in_World_War_II

The answer from an actual firefighter:

" Diesel has a much higher flashpoint. This means the speed of deflagration is much slower. It cannot convert the diesel to vapour as quickly so can't disperse the fuel as quick to spread the surface area.. "

" Leaking petrol is much more dangerous in an accident. It is far easier to ignite. If any leaking petrol contacts the exhaust or brake discs it could ignite causing rapid flame spread trapping people in the car. Diesel won't do this. "

https://www.quora.com/Is-it-possible-for-diesel-cars-to-expl...

[–] ggreer 1 day ago

It's true that diesel is harder to ignite than gasoline, but statistically they're not much safer than gasoline, and EVs have a lower fire risk than both. Last year, diesel vehicles accounted for 11% of vehicle miles traveled in the US and were responsible for around 12% of vehicle fire deaths. EVs were 3% of vehicle miles traveled and less than 1% of vehicle fire deaths.

Diesel vehicles usually have much larger fuel tanks than gasoline vehicles, so while the chances of a crash causing a diesel fire are lower, the consequences tend to be worse. If the stats are to be believed, the two factors balance each other out.

[–] leonidasrup 1 day ago

NFPA measures:

Mechanical failure or malfunction as a factor 30%

Electrical failure or malfunction as a factor 12%

Collision, knock down, run over or overturn 3%

Intentional cause 4%

https://thedailyautomotive.com/what-causes-car-fires/

Probably the biggest difference between EV cars and ICE cars can be summarized as:

"Electric cars have a lower incidence of fires compared to gasoline vehicles. However, it’s estimated that about one-third of fires in electric vehicles occur while the car is parked and unplugged."

https://thedailyautomotive.com/do-electric-cars-catch-fire/

Electric Car Fire Statistics: What the Data Actually Shows

"The most dangerous moment for an EV is not on the highway. It is in a body shop or a scrapyard."

https://thedailyautomotive.com/how-many-electric-car-fires-p...

[–] jacquesm 1 day ago

> I'm not sure

> definitely

If you're not sure, why the definitely?

Lithium packs can light up (much) faster than you sketch here. The process you describe is correct in sequence but it takes about as long to read that sentence to get to a car that is engulfed in flame. More than one person died from the combination of toxic gases and heat before they managed to get out of the car.

Lithium Ion is a very bad battery type for anything that should be safe or moves, LFP is far better and LTO is better still.

[–] ggreer 1 day ago

The "I'm not sure" referred to road damage. The "definitely" referred to risk to people.

The fact that some people have died in lithium battery fires doesn't tell you if they're a greater risk than petroleum vehicle fires. Around 500 Americans die in vehicle fires every year. Last year, EVs were around 3% of vehicle miles traveled in the US, so if they're as dangerous as petroleum vehicles, we should expect 15 battery fire deaths in 2025. The actual number seems to be 2 or 3.

[–] jacquesm 1 day ago

Petrol != diesel.

[–] ggreer 1 day ago

By petroleum I mean gasoline and diesel.

Diesel vehicles are 11% of vehicle miles traveled in the US, and around 60 people died in diesel vehicle fires last year (12% of vehicle fire fatalities). So they seem to be as dangerous as gasoline vehicles. This is probably because while diesel is more difficult to ignite than gasoline, diesel vehicles tend to have larger fuel tanks, so the harm caused by a diesel fire tends to be greater.

[–] jacquesm 1 day ago

Gasoline and diesel are very different from 'petroleum'.

Petroleum is essentially crude oil, diesel is a slightly lighter fraction and gasoline is a much lighter fraction.

Former gas station owner here, I think I know the difference. As for diesel vehicles having larger fuel tanks: they tend to be larger vehicles, and proportionally speaking they don't do much more harm because they are much easier to put out. The best way to deal with a battery fire is a controlled burn until it is spent.

As for the ratio of the fatalities: of course you need to correct for installed base.

[–] ggreer 1 day ago

Yes, I know that petroleum refers to the raw material that is used to make gasoline and diesel. I needed a term that was less cumbersome than "diesel and gasoline", and "petroleum" seemed apt. If you have a suggestion for some other term, I'm all ears.

I did correct for installed base. I'm using fatalities per vehicle mile traveled. As I said, diesel vehicles are 11% of vehicle miles traveled in the US and responsible for 12% of vehicle fire deaths in the US. EVs are 3% of vehicle miles traveled and less than 1% of vehicle fire deaths, so they're safer than diesel. The only way this could be false is if battery fire deaths are grossly underreported. That seems unlikely to me, as deaths caused by any new technology tend to be overreported. It should also be surprising that battery fire deaths are so rare, because we have little experience dealing with them. Over time, we should expect the danger of battery fires to decrease as technology and emergency training improves.

At this point, I don't know what would change your mind on this topic. I would change my mind if stats showed higher fire fatality rates per vehicle miles traveled for EVs, but that doesn't seem to be the case. I feel like I'm arguing with an anti-nuclear person. Statistics show that nuclear is extremely safe, but anti-nuclear activists ignore stats and point to nuclear accidents and the dangers of radiation. Meanwhile they ignore or discount the harms caused by alternatives. I don't see how your line of argument is any different.

[–] flanz_10 1 day ago

> Gasoline and diesel are very different from 'petroleum'.

They are refined from petroleum. I wonder if there is a dialect difference here? Also, you really seem intent on proving someone wrong over a relatively inert statement.

[–] flanz_10 1 day ago

> If you're not sure, why the definitely?

They said "I'm not sure" to the road surface question, and "definitely more of a risk to people".

Roads and people are different things.

[–] jacquesm 1 day ago

Yes, and petrol and diesel are also different things. Completely different flashpoint and activation energy.

[–] flanz_10 1 day ago

I don't recall saying they weren't. Was there any confusion in our thread about this?

Again, roads and people are different.

[–] jacquesm 1 day ago

OP uses petrol and diesel as though they are exchangeable isn't sure about the damage a fire of one kind (or the other) does to the pavement but we have to trust their expertise anyway?

[–] flanz_10 1 day ago

I don't seem to have that confusion. So, why is that my problem? Also, what they said about fires of either fuel type seems reasonable.

At this point, it seems like you're attacking them out of a minor, localized grudge, more than anything else.

AKA: troll behavior. So, I am choosing to step away. Feel free to have the last word.

[–] close04 1 day ago

Diesel fires are put out much faster than battery fires especially when the battery is huge and fully charged. Battery fires are also much hotter, up to 1000 C (~1800 F), metal fires are no joke.

Diesel damages the asphalt more in different ways. It attacks the binder in the asphalt and softens it up (after all they are both byproducts of the same crude oil precursor and just want to recombine). This process takes even days so if the cleanup is fast there's minimal damage. Most of the fuel that doesn't burn runs to the side of the road anyway.

[–] GrinningFool 1 day ago

> especially when the battery is huge and fully charged.

Huh, TIL: https://link.springer.com/article/10.1007/s10973-018-7899-y

[–] ggreer 1 day ago

Lithium battery energy density is much lower than petroleum, so the difference between a fully charged 100kWh battery (which weighs over half a ton) and an empty one is less than 3 gallons of diesel. Most of the energy expended in a battery fire is from the electrolyte reacting with the cathode material.

Over/under-charged batteries are a safety hazard because they can generate hydrogen gas which can initiate a fire, but the energy released from the fire will be pretty much the same.

[–] jacquesm 1 day ago

Lithium fires are brutal, they're extremely fast and the toxic gases are just as dangerous as the fire itself:

https://www.reuters.com/world/asia-pacific/about-20-bodies-f...

[–] ggreer 1 day ago

If we're going to count industrial accidents, then oil kills way more people. There are deaths from disasters involving wells, refineries, pipelines, tankers, and gas stations. But because they've been happening for over a century, we accept them as a fact of life. Even correcting for the much smaller install base of EVs and lower number of vehicle miles traveled, fossil fuels are far more deadly.

[–] jacquesm 1 day ago

Oh, absolutely, in the aggregate there is no contest here. I just wanted to illustrate how incredibly fast lithium fires can spread.

I've made a bit of a study of this because I use Lithium Ion batteries in volume. I take a lot of safety precautions because I realize full well how dangerous they are. At the same time I have a 25L canister of diesel and another with gasoline sitting around and I have zero expectation of either of those spontaneously combusting.

[–] klaff 1 day ago

The energy released during a fire is higher than what is accessible by discharging the battery. Here's one paper describing ratios from 1.25 to 5 depending on access to oxygen during the combustion.

https://cea.hal.science/cea-05234204v1/document

[–] ggreer 1 day ago

I'm pretty sure you're reading the paper wrong. Of the 29 tests they did, 5 were in air, and all of those were with fully charged batteries. The 5x ratio is the difference between electrical energy stored in the battery and energy released in atmosphere. They did not measure different states of charge versus energy released in atmosphere. That's why the figures for the nitrogen and atmosphere tests are bar charts instead of line charts.

The relationship between energy stored and energy released was mostly determined by how big the batteries were, not their state of charge. Only 4 of their tests varied state of charge, and those were all in vacuum (with cells #1 & #6), and state of charge was never below 60%.

[–] klaff 1 day ago

I wasn't clear, sorry, and you understood the point from the article. I thought you might have been assuming that a 100 kWh battery would produce 100 kWh of energy when burned, and I was trying to point out that when the battery is burned, you can get a much larger amount of energy. My apologies for wasting your time.

[–] tartoran 1 day ago

Which fumes are worse, from EVs or diesel filers?

[–] jordanb 1 day ago

You don't want to breathe either, but the answer generally is battery fires which can produce extremely toxic gas like hydrogen flouride

https://m.youtube.com/watch?v=lADLvwAJs-c

https://en.wikipedia.org/wiki/Hydrogen_fluoride

[–] ourmandave 1 day ago

Yeah, that's on Derek Lowe's list of things he won't work with.

https://www.science.org/content/blog-post/things-i-won-t-tou...

[–] close04 1 day ago

Honestly no idea. But after receiving multiple fire trainings and talking to trained firemen, I have to say that all else being equal (and gun to the head because I actually want neither) I'll take a diesel fire over a battery fire any day.

A lot of dangerous fumes come from the other material burning around the source. And at 1000C plenty of neighboring stuff decides to burn.

[–] breckenedge 1 day ago

Lithium fuel can melt asphalt seams

[–] darksaints 1 day ago

Yes

[–] zerocool0101 1 day ago

how?

[–] xxs 1 day ago

You can't use a fire extinguisher for one to put it down. Li-Ion effectively self-sustain when ignited.

The only version of putting it down is letting it burn out.

Morealso diesel is hard to ignite on its own, hence the ICE use compression not spark

[–] darksaints 1 day ago

Not only that, but the fires can burn hot enough to melt the asphalt, and at high enough temperatures the bitumen in the asphalt will vaporize and feed the flames.