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I've always wondered the same about a vehicle carrying around 15 - 20 gallons of highly flammable and explosive liquid fuel. What happens in an accident, where

I've always wondered the same about a vehicle carrying around 15 - 20 gallons of highly flammable and explosive liquid fuel. What happens in an accident, where a spark in the wrong place with the correct mixture of fuel and oxygen can cause an explosion or hot burning fire? There's been a few times I've driven by a car fire, and even from the opposite side of a divided 4-lane highway, the heat I felt was impressive.

throwaway0a5e 6y ago
I'm really sick about this whattaboutism that every internet discussion about electric cars invariably devolves into at least in part. Fire requires fuel, oxygen and ignition (heat). Liquid fuels require external ignition. Batteries do not. But you also have to pump liquid fuels around and generally handle them more to make them do work. Batteries are more dangerous on a fundamental/conceptual level because they have everything they need to release their energy all at once. So we build them with hard casings for the same reason we build large safety factors into pressurized gas containers so in practice it doesn't really matter. Batteries and liquid fuels aren't really better or worse than each other from a "much safety or "won't somebody think of the children" point of view. They just require slightly different engineering considerations for an equivalent level of safety. This is directed just as much (ore maybe even more) at the parent comment as it is at you.
- derekp7 6y ago
  I agree with you on this, hence phrasing my comment as a reverse "what-aboutism". Handling of liquid fuels has improved quite a bit to where it typically isn't a problem. Whereas at one time you had cars (I'm thinking of a 60's Mustang) where if it got rear-ended gas from a ruptured tank could slosh into the passenger compartment. This isn't much of an issue with modern car designs. And cars have come along way in the ability to protect the occupants. That same protection measures can be applied to the battery compartment if necessary (steal roll cage, elastic restraint system, air bags). Yes, these things need to be thought about, and yes we do have agencies such as the NTSB and insurance standards that will solve the problem.
- EricE 6y ago
  Capacitors are not batteries nor liquid storage. Unlike chemical based energy storage, capacitors can dump all their energy at once. Literally! Look up the definition of an explosion. I’m super excited about super capacitors - I think they are going to be required in order to make electric cars truly feasible - but the concerns around the safety of them should be dismissed just because they might hold up progress!
  - throwaway0a5e 6y ago
    There's some pretty basic electrical trickery that can be applied to limit current in the discharge direction without limiting it in the charge direction. I'm dismissing these concerns not because they might hold up progress but because they're well withing what Donald Rumsfeld would call a "known known" of engineering difficulties.
  - Tostino 6y ago
    Generally super capacitors don't have quite the same oomph as a regular electrolytic capacitor in charge/discharge. They lie somewhere between electrolytic and modern Lithium chemistries. Still can be super dangerous...
sandworm101 6y ago
The speed of a chemical fire, be it from a fuel spill or chemical battery, is limited by chemistry. Even a fully involved burning fuel tank is limited by the availability of oxygen, the math involves wind speeds and circulation of gas over a flame. Short-circuit a normal battery and the math is all about heat and chemical bonds. Short-circuit a capacitor and the math become quantum, involving numbers like the speed of light.
- Koshkin 6y ago
  Depends on the fuel. The speed of the 'chemical fire' (which is what it is) inside a shell casing, for example, is very high.
bluGill 6y ago
Gasoline is only flammable in a narrow range of air/fuel ratios. Too much air and there isn't enough fuel to sustain combustion, too much fuel and there isn't enough air. There are plenty of people who have demonstrated dropping a match into a gas can and the match goes out with only a slight poof of a flame. Full gas can can sometimes survive the building they are in burning down (if the can is sealed - doesn't melt - there is never enough air inside to light the fuel) That isn't to say gasoline isn't dangerous. However it isn't quite as dangerous as you seem to think.

throwaway0a5e 6y ago

I'm really sick about this whattaboutism that every internet discussion about electric cars invariably devolves into at least in part. Fire requires fuel, oxygen and ignition (heat). Liquid fuels require external ignition. Batteries do not. But you also have to pump liquid fuels around and generally handle them more to make them do work. Batteries are more dangerous on a fundamental/conceptual level because they have everything they need to release their energy all at once. So we build them with hard casings for the same reason we build large safety factors into pressurized gas containers so in practice it doesn't really matter. Batteries and liquid fuels aren't really better or worse than each other from a "much safety or "won't somebody think of the children" point of view. They just require slightly different engineering considerations for an equivalent level of safety. This is directed just as much (ore maybe even more) at the parent comment as it is at you.

derekp7 6y ago
I agree with you on this, hence phrasing my comment as a reverse "what-aboutism". Handling of liquid fuels has improved quite a bit to where it typically isn't a problem. Whereas at one time you had cars (I'm thinking of a 60's Mustang) where if it got rear-ended gas from a ruptured tank could slosh into the passenger compartment. This isn't much of an issue with modern car designs. And cars have come along way in the ability to protect the occupants. That same protection measures can be applied to the battery compartment if necessary (steal roll cage, elastic restraint system, air bags). Yes, these things need to be thought about, and yes we do have agencies such as the NTSB and insurance standards that will solve the problem.
EricE 6y ago
Capacitors are not batteries nor liquid storage. Unlike chemical based energy storage, capacitors can dump all their energy at once. Literally! Look up the definition of an explosion. I’m super excited about super capacitors - I think they are going to be required in order to make electric cars truly feasible - but the concerns around the safety of them should be dismissed just because they might hold up progress!
- throwaway0a5e 6y ago
  There's some pretty basic electrical trickery that can be applied to limit current in the discharge direction without limiting it in the charge direction. I'm dismissing these concerns not because they might hold up progress but because they're well withing what Donald Rumsfeld would call a "known known" of engineering difficulties.
- Tostino 6y ago
  Generally super capacitors don't have quite the same oomph as a regular electrolytic capacitor in charge/discharge. They lie somewhere between electrolytic and modern Lithium chemistries. Still can be super dangerous...

sandworm101 6y ago

The speed of a chemical fire, be it from a fuel spill or chemical battery, is limited by chemistry. Even a fully involved burning fuel tank is limited by the availability of oxygen, the math involves wind speeds and circulation of gas over a flame. Short-circuit a normal battery and the math is all about heat and chemical bonds. Short-circuit a capacitor and the math become quantum, involving numbers like the speed of light.

Koshkin 6y ago
Depends on the fuel. The speed of the 'chemical fire' (which is what it is) inside a shell casing, for example, is very high.

bluGill 6y ago

Gasoline is only flammable in a narrow range of air/fuel ratios. Too much air and there isn't enough fuel to sustain combustion, too much fuel and there isn't enough air. There are plenty of people who have demonstrated dropping a match into a gas can and the match goes out with only a slight poof of a flame. Full gas can can sometimes survive the building they are in burning down (if the can is sealed - doesn't melt - there is never enough air inside to light the fuel) That isn't to say gasoline isn't dangerous. However it isn't quite as dangerous as you seem to think.