Guy buys hydrogen car but can't buy hydrogen

Forums › Transport (cars, bikes and boats) › Guy buys hydrogen car but can't buy hydrogen

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2123 posts

Uber Geek

#2833577 16-Dec-2021 16:32

MikeB4:

Back when I was involved there was an accident where a CNG powered vehicle was tail ended by a truck. The rear of the Holden was crushed all the way to the B pillar, the CNG tank was intact. Vehicles with CNG and LPG were running around banging into each other for well over a decade and it was not Armageddon.

Ok, but there are examples out there where a CNG tank has exploded. A CNG tank is also the fraction of the pressure of a Hydrogen tank. All it takes is a manufacturing flaw or fatigue.

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MikeB4

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#2833584 16-Dec-2021 16:46

CNG tanks were filled to circa 3500psi. A LPG tank was very low at circa 200psi. The odds of a hydrogen tank rupturing would be so low as to be virtually zero.

Obraik

2123 posts

Uber Geek

#2833604 16-Dec-2021 17:01

In a perfect world, sure. Unfortunately, we don't live in a perfect world.

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Handle9

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#2833612 16-Dec-2021 17:14

MikeAqua:

MikeB4:

Those old Prius models are garbage for taxis or Uber. As well as sod all headroom (I am 190cm) they cannot fit a wheel chair. I have lost count how many times one of those abominations turn up even after I have said i am using a chair.

That's appalling.

When I've used basic Uber in Aussie a SUV or large sedan turns up in good repair, smelling nice with the AC already running. Why the difference between here and there?

Used Japanese imports

scuwp

3885 posts

Uber Geek

#2833615 16-Dec-2021 17:18

Obraik:

MikeB4:

Back when I was involved there was an accident where a CNG powered vehicle was tail ended by a truck. The rear of the Holden was crushed all the way to the B pillar, the CNG tank was intact. Vehicles with CNG and LPG were running around banging into each other for well over a decade and it was not Armageddon.

Ok, but there are examples out there where a CNG tank has exploded. A CNG tank is also the fraction of the pressure of a Hydrogen tank. All it takes is a manufacturing flaw or fatigue.

In my past life I have attended plenty of crashes where the petrol tank on an ICE vehicle has ruptured and the car has caught fire, usually with the worst possible outcome. I don't think the risk would be any greater than what is currently out there, and no one is overly concerned they are driving around in a steel box powered by small explosions carrying highly flammable liquid.

Lazy is such an ugly word, I prefer to call it selective participation

SomeoneSomewhere

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#2833641 16-Dec-2021 18:43

MikeB4:

Hydrogen tank testing and safety.....

"To further ensure safety, these tanks undergo cycling tests in which they are pressurized and depressurized many more times than they would be during their lifetime on a vehicle. For example, advanced carbon-composite tanks have been cycled more than 500,000 times to maximum operating pressure without leaking, whereas a tank on a vehicle filled once a week for 20 years undergoes slightly more than 1,000 cycles. Tanks are exposed to pressures above normal to simulate fault management. The tanks are also dropped 6 feet when empty, shot with a rifle, burned, and exposed to acids, salts, and other road hazards to validate that they are safe even under severe or unusual conditions."

"In the unlikely case that an advanced composite tank leaks, it can be removed from service without incident. It is highly unlikely that these tanks will fail in a way that will directly endanger the occupants of a hydrogen-fueled vehicle. These tanks have remained intact in collisions and in vehicle fires, and, when tested after such events, have passed various pressure tests. (See Table 2). In case of vehicle fires or events in which fire from another vehicle may engulf the tank, the tank's pressure relief device is activated when the temperature of the tank exceeds a set point (typically 102°C/ ~216°F). When the pressure relief device is activated, the hydrogen gas in the tank is released in a safe manner. This safety procedure is validated through performance tests conducted in accordance with an existing standard (NGV2-2000)."

[...]

CNG tanks were filled to circa 3500psi. A LPG tank was very low at circa 200psi. The odds of a hydrogen tank rupturing would be so low as to be virtually zero.

I'm not exactly sure how safe a controlled pressure release is going to be. It's still going to be more-or-less a hydrogen blowtorch with an invisible flame. Better than a catastrophic failure, yes...

And a 700 bar H2 tank is 10,000psi. Hydrogen is also really easily ignitable.

It's also worth looking at install base - Lithium cars have done a lot more miles than hydrogen. I expect they've also now well overtaken CNG & LNG vehicles.

As for recycle-ability, I would expect the high value of Lithium and other components is going to lead to good recovery.

Deleting the battery entirely isn't really going to be an option for an H2 vehicle. You lose the advantages of regen braking. I also expect that there are issues with ramp rate in the fuel cell, and the fuel cells are rather expensive. I'm actually pretty surprised there's a 95kW stack in the Nexo.

Also curious whether they start being a risk for theft in the same way catalytic converters are.

MikeAqua

7785 posts

Uber Geek

#2836013 20-Dec-2021 14:58

In everything I've read engineers are less concerned with a hydrogen leak than with a natural gas tank. It's to do with the speed at which hydrogen dissipates and the 'flame speed' when it burns.

I've also read an article about some engineers in Scotland who have been trying for three years to cause an explosion with a hydrogen has stove. They can't do it because the gas is so buoyant and so dispersive.

Mike

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Rikkitic

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#2836030 20-Dec-2021 15:23

Oh the humanity!

Plesse igmore amd axxept applogies in adbance fir anu typos

dacraka

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#2836051 20-Dec-2021 16:03

RobDickinson:

I know companies whoa are buying Kona because the tesla looks too expensive even though its cheaper..

Surely being the safest car in the world should take precedence! *sigh*

rjh

57 posts

Master Geek

#2836213 21-Dec-2021 09:04

mudguard:

..

He says electric is absolutely perfect for consumer vehicles that only do a couple hundred hours of running a year. ...

That's exactly backwards (and braindead). We need to prioritise where we electrify first, for the most immediate significant impact. Electrifying vehicles that are mostly parked up is insane, we should be already electrifying trucks and buses - which we are, but this is painfully slow. In fact, Wellington even went backwards when they removed the trolley buses.

Our neighbour's 2x Teslas are achieving absolutely nothing, unlike our electric rubbish trucks (and electric ferry).

rjh

57 posts

Master Geek

#2836217 21-Dec-2021 09:13

Zeon:

Coming back to the topic at hand, it seems to me that battery is not viable compared to a gaseous or liquid fuel for vehicles/machinery that have very high utilisation time. For example, during a harvest you have a narrow window to get the combine harvester across all the fields so could work day and night. With liquid fuels like petroleum there is practically no downtime as the tank can accept the fuels as quickly as you can get it in there.

This doesn't seem possible with a battery vehicle.

Or a bus that runs 17 hours straight per day.

Is Hydrogen not a valid fuel if you want to "decorbonise" and not use petroleum fuels?

And yet BYD is making and selling tens of thousands of electric buses and trucks and forklifts; I'm not seeing any similar numbers for hydrogen.

Hydrogen really is just a distracting dream; the numbers just don't add up.

Even worse, this is being promoted because it is a way to centralise and more easily control energy distribution. Fuel companies don't want to cede their position to generation and lines companies.

Sidestep

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#2836227 21-Dec-2021 09:59

rjh:

And yet BYD is making and selling tens of thousands of electric buses and trucks and forklifts; I'm not seeing any similar numbers for hydrogen.

Hydrogen really is just a distracting dream; the numbers just don't add up.

Even worse, this is being promoted because it is a way to centralise and more easily control energy distribution. Fuel companies don't want to cede their position to generation and lines companies.

There's a place for both.

EV's are the proven path to decarbonization of light vehicles - cars, light trucks, buses etc.

Hydrogen's the way to decarbonize heavy industry - fertilizers, steel, methanol, shipping, heavy off-road machinery..

In between are all sorts of things where one (or both) will prove the most efficient - aviation, regional trucking, trains, and much more.

- there are 30,000 hydrogen fuel cell forklifts just in the US & Canada..

SomeoneSomewhere

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#2836243 21-Dec-2021 10:28

This suggests that in the US alone, in 2008 there were ~50k battery electric forklifts shipped per year.

https://www1.eere.energy.gov/hydrogenandfuelcells/pdfs/forklift_anl_esd.pdf

Commercial hydrogen is also currently produced mostly by cracking natural gas. While that avoids point-of-use emissions, it doesn't help with CO2 much. Although the same could be said for electricity.

SomeoneSomewhere

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#2836246 21-Dec-2021 10:32

Aircraft are an obvious use case for hydrogen. Weight is critical, as at short turn around times and energy density.

On the other hand, I think trains would probably mostly go BEV. You can recharge on portions of the route that are under the wires, so super far charge times aren't essential. More adhesive weight isn't really an issue in freight, and regent braking can deliver big savings.

RobDickinson

1524 posts

Uber Geek

#2836250 21-Dec-2021 10:35

I'm not sure Aircraft are, you cant easily use the wings for h2 tanks and all the weight is in the tanks and conversion to power.

yes the hydrogen itself is light but people seem to forget it cant just exist on its own.

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