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Hydrogen back of the envelope

2017-05-05 15:32:28.068019+00 by Dan Lyke 2 comments

Just saw a YouTube ad for the Toyota Mirai which claimed a 312 mile range. Hydrogen at 700bar has an energy density of about 5.6 mega Joules per liter, gasoline 34.2 MJ/L.

That suggests that a 12 gallon gasoline equivalent tank takes about 10 cubic feet of hydrogen, plus extra material necessary to hold the pressure. So where the heck are they putting the tank? Does this vehicle not have a trunk? (I think the last time I asked myself this question I concluded they'd also have to give up the back seat.)

And the refueling process in the video looked a lot like a normal gas station, but given the pressures involved, that can't be right either, can it?

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#Comment Re: Hydrogen back of the envelope made: 2017-05-08 23:06:50.842596+00 by: TheSHAD0W

You're assuming the vehicle has the same miles per megajoule rating. The motor may be a lot smaller and have a lot less power.

#Comment Re: Hydrogen back of the envelope made: 2017-05-11 23:30:35.629253+00 by: Dan Lyke

Ah, good point... Yeah, I guess we have to see some performance numbers.

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