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“Battery EV” vs “Hydrogen Fuel cell EV”

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nctnico:

--- Quote from: richard.cs on November 15, 2021, 10:48:42 pm ---
--- Quote from: tom66 on November 15, 2021, 10:37:54 pm ---What, so natural gas is a totally safe and non-explosive gas?

--- End quote ---

In comparison to hydrogen, yes. Methane in air is explosive from 5% to 17%, hydrogen 4% to 75%. In practice it means hydrogen is much more likely to make an explosive mix, even before you account for its greater tenancy to leak in the first place due to the small molecule.

--- End quote ---
OTOH hydrogen is much lighter than air (nitrogen / oxygen mix) thus more likely to dissipate than to build up in a basement like methane can do because it is heavier than air.

TimFox:

--- Quote from: nctnico on November 15, 2021, 11:30:02 pm ---
--- Quote from: richard.cs on November 15, 2021, 10:48:42 pm ---
--- Quote from: tom66 on November 15, 2021, 10:37:54 pm ---What, so natural gas is a totally safe and non-explosive gas?

--- End quote ---

In comparison to hydrogen, yes. Methane in air is explosive from 5% to 17%, hydrogen 4% to 75%. In practice it means hydrogen is much more likely to make an explosive mix, even before you account for its greater tenancy to leak in the first place due to the small molecule.

--- End quote ---
OTOH hydrogen is much lighter than air (nitrogen / oxygen mix) thus more likely to dissipate than to build up in a basement like methane can do because it is heavier than air.

--- End quote ---

Hydrogen (H2 in nature) has a molecular weight of approximately 2.
Methane (CH4) has a molecular weight of approximately 16.
Nitrogen (N2) has a molecular weight of approximately 28.  Oxygen (O2) is approximately 32. 
Far above the boiling point, the Ideal Gas Law gives a density proportional to the molecular weight.
Therefore, as you said, hydrogen is much lighter than air, but methane is roughly half as heavy as air.

james_s:
I remember in my chemistry class in high school we learned about that, the teacher used a pan of soapy water and methane from the gas tab on the bench to make large bubbles which floated up toward the ceiling which he poked with a flame on the end of a stick. It was a lot of fun, that teacher was well known for flames and explosions, he was very popular with students.

PlainName:
Charging stations: they're not going to be like current filling stations since the car will need to sit for some time to charge. Currently car comes in, fills tank, gone in a couple of minutes. Once that flow is slowed down, there's a limit to how many cars can be hanging around, so throughput is going to be much lower and the filling station would need to make more profit per car (ignoring that more stations would be needed to maintain overall filling rates).

On the plus side (for the filling station) they'll have a captive audience to sell stuff to, just like the airlines get to make you walk through shopping centers en route to the aircraft (and than sit in cafes for 2 hours).

rstofer:

--- Quote from: dunkemhigh on November 16, 2021, 12:45:53 am ---On the plus side (for the filling station) they'll have a captive audience to sell stuff to, just like the airlines get to make you walk through shopping centers en route to the aircraft (and than sit in cafes for 2 hours).

--- End quote ---

I'll bet shopping malls are early adopters.  They are common at pharmacies around here.  But, really, there's nothing to do in a pharmacy.  But put them in a mall and watch sales grow.

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