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points by close04 1 day ago | 0 comments

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.