Nope, tank mass scales with volume because bigger tanks need thicker walls: https://en.wikipedia.org/wiki/Pressure_vessel#Scaling
In particular, pressurized automotive-size hydrogen tanks aren't made from metal at all, they are typically epoxy/kevlar/carbon fiber composites.
At around 2000 wh/kg you are equivalent to diesel drivetrain energy density both size and weight based on my rough math.
Expensive large hydrogen tanks in a trailer with high pressure lines to tractor seems like it would cause safety and cost issues offsetting much of the benefit.
But I'm always amused to think that posters on HN give more credence to their back-of-the-napkin calculations over opinions of, say, folks at Toshiba, Volvo or Daimler.
You should alway try to understand the math / science and make your own judgements rather to falling for arguments from authority. This isn't always feasible but I think most people can do enough to weed out the snake oil to a much better degree than we seem to be doing as a society now.
Note this will also make you a better engineer / programmer in my experience.
For instance the Semi being announced in 2017 I said no way, but their range numbers where not outlandish, they just conveniently left off weight numbers for the tractor and cost of the battery seemed to high at the time. What I missed was how quickly battery cost are coming down and energy density going up, however they still haven't delivered a tractor yet so...
Tesla has a real tech lead, not sure if they can keep it and they are way over valued stock wise.
Nikola complete BS.
H2 offered the highest ISP, ie energy per fuel mass, and originally they wanted the Shuttle to be a single stage to orbit vehicle. But Hydrogen also added larger, much heavier tanks and engines didn’t have enough thrust for that. So they had to add large Solid Rocket Boosters to get off the pad. And all they additional dry mass meant the higher ISP of H2 was wasted.
And now the SLS is repeating those mistakes, not because engineers didn’t learn those lessons, but because politicians require them to repeat them.
Engineers recommending Hydrogen for cars are influenced by regulatory requirements and benefits, and politically by company objectives. If your CEO says Hydrogen is important to use because our government and regulators say it is, you as an engineer will find a way to make the best of a bad choice.
They also have large resources and are willing to experiment in things (especially if there are incentives around it from government, etc) - and even if it fails entirely they'll likely get useful and actionable data and results that still can help the company.
Which umm shows you never know who’s posting here.
The Emperor and the downtrodden, the Ivey League and the community college, you'll find the same mathematics wherever you go.
Some may have an advantage in innovation or inspiration, but it should he fair trivial for any sufficiently motivated individual to check the numbers.
It's also not inconceivable that if we have more base load power generation (e.g. through more nuclear) then we could generate hydrogen at night with the excess.
Liquid hydrogen at -253c that is more energy intensive to make than high pressure.
Not sure I see that being practical.
For trucks where you need bigger tanks, both autonomy and boil-off rate improve by themselves due to the square-cube-law. And you can use the boil-off to charge the batteries in your hybrid electric powertrain, run auxiliary systems etc.
The LH2 trucks currently under planning have sophisticated fuel management systems where the driver inputs where she will stop and for how long, and the truck will optimize LH2 consumption and battery SoC before arriving at the stop point.
As for LH2 versus compressed: do you actually know how energy demanding a hydrogen compression train is? Compressing a low molecular weight gas to 700 bar is just fundamentally inefficient.
At the scale required for mass adoption of hydrogen fuels, both compression and liquefaction are talking 6-8 kWh/kg. For comparison the energy content in hydrogen itself is 33 kWh/kg. So naturally there is great interest in recovering as much as possible of that work before consumption.
"To stay a liquid, hydrogen must be cooled and maintained at cryogenic temperatures of, at warmest, −253 °C (20.1 K; −423.4 °F). When not using fuel, the Hydrogen 7’s hydrogen tank starts to warm and the hydrogen starts to vaporize. Once the tank’s internal pressure reaches 87 psi, at roughly 17 hours of non-use, the tank will safely vent the building pressure. Over 10–12 days, it will completely lose the contents of the tank because of this"
At that temperature even sloshing around adds enough energy to heat and cause venting much sooner another reason its not great for mobile use.
Looks like Air Liquide made a different one that you are quoting perhaps an improvement, still high vacuum double walled, so you lose all your fuel in a month instead, thats progress.
This shows liquefaction to be about twice as energy intensive as compression (1.3 vs 3.4 kWh/kg theoretical 6 vs 13 kWh/kg actual) [2] So please point me to better info.
1. https://en.wikipedia.org/wiki/BMW_Hydrogen_7
2. https://www.hydrogen.energy.gov/pdfs/9013_energy_requirement...
Hydrogen has a better gravimetric scaling than batteries - as stored energy increases, the fixed weight of the fuel cell is amortised over more energy and the weight of high pressure tanks goes up with their surface area while the energy stores goes up with volume.
So for applications where you want to store a lot of energy and are weight but not volume limited, hydrogen might make enough sense to pay the efficiency penalty required to turn electricity into hydrogen and back again.
That's why it makes more sense for big trucks than it does for passenger cars where volume limitations matter a lot more and where total energy is less.