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Another fun quirk: The hydrogen dispenser frosts up pretty fiercely during fueling. There's a station near SFO that I stumbled across where the dispenser was too cold to dare touch.


I wonder if that depends on the pressure of the car? I vaguely recall they sold at two pressures when I looked long ago. Could stepping down from the stored pressure to much lower car pressure cause the icing?

oh, and I remember one other thing. Even though the mirai drivers were getting free fuel (at the beginning), I think H2 was like the equivalent of $17/gallon marked on the pump.


I have a Toyota Mirai. The cheapest hydrogen available to me is $30/kg, and many stations (those owned by True Zero) charge $36/kg. When I bought my Mirai, it was $19.70/kg.

The reason I bought a Mirai is because I wanted to go zero-emissions but I’m an apartment dweller with no EV charging options. The Mirai is the best vehicle I’ve driven in terms of its features and comfort. However, once my fuel card ran low, I ended up getting a gas-powered car since $36/kg is prohibitively expensive for me to pay out of pocket.

I hope the hydrogen situation improves, since not everybody has convenient access to an EV charger, not to mention the cost of electricity in PG&E territory.


> Could stepping down from the stored pressure to much lower car pressure cause the icing?

A drop in temperature will be (more or less) proportional to a drop in pressure. See https://en.wikipedia.org/wiki/Ideal_gas_law


Careful, the ideal gas law doesn’t really tell you this at all.

The nice case is adiabatic expansion, and at least the sign of the temperature change has the decency to behave the way one would expect:

https://en.m.wikipedia.org/wiki/Adiabatic_process

The more realistic case for a gas station is Joule-Thomson expansion, and it thoroughly defies basic intuition: https://en.m.wikipedia.org/wiki/Joule%E2%80%93Thomson_effect




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