Design Con 2015

Are EVs safer than gas-powered cars?

-September 19, 2013

The other day I heard someone on TV make a casual remark, claiming that battery-only electric vehicles (EVs) were inherently safer than conventional internal-combustion vehicles because, "you know, they don't have any gasoline or nasty stuff like that." (He apparently wasn't referring to crash-worthiness, only "static" safety.) That thought made me wonder: is it really so?

There's no doubt that gasoline is powerful stuff, with a high energy density by weight and volume; it's about three to ten times that of the best batteries—in fact, those high density numbers are gasoline's largest virtue (diesel fuel has higher density numbers than gasoline, see here, but is less volatile, see here).

While EVs do not have gasoline (or diesel) on board, they do have other fluids: various coolants for the battery packs, electronics, and power-control subsystems; fluid for the non-regenerative brake system (regenerative braking is only effective at higher speeds); fluid for the air conditioning, and more.

The Chevrolet Spark "pure" EV won't suffer from gasoline leaks or fires, that's for sure.

It's not just the fluids that are a concern in EVs, either. You have that high voltage from battery packs that can also deliver lots of amps, which is a potentially dangerous combination. The batteries themselves have issues as well, since they are electrochemical energy-storage/delivery subsystems.

The "gasoline is more dangerous" argument doesn’t appeal to me. Almost everything has danger and impact; it's just how we learn to live and work with it. The fact is that we have learned to manage gasoline's virtues and vices pretty well. You don’t hear about many spontaneous explosions of gasoline cars that are just sitting in the parking lot.

I think the deeper answer to the question of danger is like so many other real-world issues: it depends on your perspective, priorities, and how you assess the risk. After all, you can drill down into the constitute components of almost anything and find trouble: water is composed of two explosive gaseous elements; ubiquitous salt is a combination of corrosive chlorine gas and nasty sodium metal. How we judge danger and impact depends on how broadly or narrowly you look at things, as a recent very non-politically correct article in IEEE Spectrum - see "Unclean at any Speed" - made evident.

What do you think? Are pure EVs basically safer "objects" than gasoline vehicles? Or this a case of misplaced perspective?

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