4 ms·

I'm not an expert in fuel cell efficiency, I'd read that number somewhere and a quick google confirms it: https://www.sciencedirect.com/topics/engineering/round

by dTal 5y ago

I'm not an expert in fuel cell efficiency, I'd read that number somewhere and a quick google confirms it: https://www.sciencedirect.com/topics/engineering/round-trip-efficiency https://www.sciencedirect.com/topics/engineering/round-trip-... The energy density situation looks less attractive when you include the beefy 350-bar storage tanks, and the fuel cell itself. A battery just has two wires sticking out and that's it.

jfim 5y ago
> A battery just has two wires sticking out and that's it. What about thermal management, the outer shell that can hold the battery cells and modules, and the battery management system?
- dTal 5y ago
  Sure, but a hydrogen fuel cell system has most of that too. My point was just that hydrogen can't be directly compared to batteries because it's just the fuel, while batteries are the complete system. I guess I worded it badly.
nightfly 5y ago
> A battery just has two wires sticking out and that's it. Considering the heating/cooling mechanisms required for EV batteries this is a pretty disingenuous statement. Not even considering the highly-toxic fire risk with Li-ion.
- dTal 5y ago
  Well okay, but if we're bringing those things into it, hydrogen requires cryogenic storage and is, ah, famously flammable, even when it's not pressurized to 350 bar. I wasn't saying Li-ion is perfect - all I was trying to say was that if you want to compare like with like, you can't compare batteries with just hydrogen - the hydrogen is just the fuel, while the battery is both the fuel and the generator.
  - darksaints 5y ago
    You need to do some more research. Hydrogen is 57 times lighter than air, which means in the case of a leak, it disperses almost instantaneously...almost always completely dissipating before having the chance to ignite at all. Rapid depressurization will freeze nearly everything in it's path, minimizing your chances of a heat induced ignition. And unless you're giving it liquid oxygen, you have almost no chance of an explosion. https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is-hydrogen-fuel/ https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is...
  - pfdietz 5y ago
    > hydrogen requires cryogenic storage Not for grid-scale stationary storage, it doesn't. You store it underground as compressed gas, just as many millions of tonnes of natural gas are stored today.
- shiftpgdn 5y ago
  Gas cars are 11x more likely to catch fire than an EV.

by dTal 5y ago

jfim 5y ago

> A battery just has two wires sticking out and that's it. What about thermal management, the outer shell that can hold the battery cells and modules, and the battery management system?

dTal 5y ago
Sure, but a hydrogen fuel cell system has most of that too. My point was just that hydrogen can't be directly compared to batteries because it's just the fuel, while batteries are the complete system. I guess I worded it badly.

nightfly 5y ago

> A battery just has two wires sticking out and that's it. Considering the heating/cooling mechanisms required for EV batteries this is a pretty disingenuous statement. Not even considering the highly-toxic fire risk with Li-ion.

dTal 5y ago
Well okay, but if we're bringing those things into it, hydrogen requires cryogenic storage and is, ah, famously flammable, even when it's not pressurized to 350 bar. I wasn't saying Li-ion is perfect - all I was trying to say was that if you want to compare like with like, you can't compare batteries with just hydrogen - the hydrogen is just the fuel, while the battery is both the fuel and the generator.
- darksaints 5y ago
  You need to do some more research. Hydrogen is 57 times lighter than air, which means in the case of a leak, it disperses almost instantaneously...almost always completely dissipating before having the chance to ignite at all. Rapid depressurization will freeze nearly everything in it's path, minimizing your chances of a heat induced ignition. And unless you're giving it liquid oxygen, you have almost no chance of an explosion. https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is-hydrogen-fuel/ https://hydrogen.wsu.edu/2017/03/17/so-just-how-dangerous-is...
- pfdietz 5y ago
  > hydrogen requires cryogenic storage Not for grid-scale stationary storage, it doesn't. You store it underground as compressed gas, just as many millions of tonnes of natural gas are stored today.
shiftpgdn 5y ago
Gas cars are 11x more likely to catch fire than an EV.