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So just whipping some numbers together:

The now dead FCX Clarity does 60mpkg on Hydrogen, so to equal the BEV i3 range call it two kilos at similar efficiency.

2kg of hydrogen occupies 24,000 litres at room temperature and pressure. So to cram 120 miles of Hydrogen into the 9 litre tank means a pressure of over 2500 bar. That's a lot. The BMW Hydrogen 7 had a tank (at 170 litres, double the normal size) pressurised to 700 bar to hold liquid Hydrogen. That's going to be a heavy old tank...

EDIT: the pressure at 35,000 ft at the bottom of the Challenger Deep is just over 1000 bar. Suffice to say, no one's making a 2500 bar tank under mass production, and so if the i3 is used, I suspect the whole rear end will be the tank - much like the Mini E's was filled with batteries, so I'm not calling BS just yet - but I don't see how they can sell the same car with it's current packaging.

EDIT EDIT: liquefying it can get your 2kg down to around 40 litres, but keeping your tank cold will be a challenge. The Hydrogen 7 slowly discharged over days as the insulated and supercooled tank warmed and vented the resultant vapour. Sounds like a faff to me.

EDIT EDIT EDIT: FCX Clarity tank is 170 litres at 350bar to get 240 miles.
 
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170 litres!? What? My Volvo S60, hardly a small car had a 68 litre diesel tank. And the Clarity had a tank 2 1/2 times bigger? Is it just me or is this wishful thinking on BMW/Toyota's part?
 

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You can get 170 litres into an i3 - it just might not have any boot space or rear seats. Might work quite well as a test bed though.

Mind you having a load of Rechargeable AAs behind your back is one thing, a big pressurised tank is another. Been trying to find footage of what happens when a pressurised H2 tank is punctured and ignited. Somebody's going to have to do that test on a FCEV at some point.
 

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Discussion Starter #6
FCX Clarity tank is 170 litres at 350bar to get 240 miles.
Based on that FCX Clarity tank size then to give the i3 a 120 mile range would equate to a 85 litre tank (ignoring weight savings of i3).

The manufacturer figures for the new Toyota Mirai are 435 miles out of 5kg hydrogen which equates to 87m/kg. That seems to be a very big increase in efficiency compared to the older Honda and is likely to be less in 'real world' use but using that data would reduce the 85 litres down to 59 litres. That's beginning to sound more viable to package in the i3 but that's a lot of assumptions!
 

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BMW have always said that hydrogen is the future*, so who knows!

Is this why Toyota have dropped EVs does anyone know? So BMW handles the majority of EV development (I know they have hydrogen too) and Toyota focuses on Hydrogen? A bit like how my friends and I got through GCSE science together. ;)


*I mean literally, at the MINI E launch the higher-ups kept telling me this!
 

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I suppose the H2 i3 could lose some (most) of it's battery to gain some volume for H2 storage, and the place where the petrol rex lives is where the fuel cell stack goes.

Still, don't have a hydrogen tap at my house, so don't really care if they make it or not!
 
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I suppose the H2 i3 could lose some (most) of it's battery to gain some volume for H2 storage, and the place where the petrol rex lives is where the fuel cell stack goes.
I'd discounted the battery template as being too slab like to fit the template for a pressurised tank, which I would think would need to be circular in cross section with no right angles. Not an expert in such tanks. I know the Bloodhound SSC guys though - I might ask them about it. We once had a good yarn about propellant tanks. You had to be there.
 

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There could be multiple tanks, laid flat as cylinders, I seem to remember seeing so e hydrogen car prototypes like that.
 

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The best higher pressure containers are sphere and doughnut shapes.

My pure guess is that the early H₂economy cars will be hybrids with limited H₂ range say 50 miles. mainly to get people used to the idea.

Hydrogen is fairly safe, taking reasonable precautions. I have actually dived on a H₂/O₂ mix experimentally.
 
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