On 20/04/2019 14:45, NY wrote:
"Tim Streater" wrote in message
.. .
In article , Steve Walker
wrote:
Electric cars are unlikely ever to have sufficiently quick charging
and when they make affordable Hydrogen powered cars, that is when
petrol and diesel will have a viable replacement - assuming enough
power can be generated to release the Hydrogen in the first place.

What is the hydrogen going to be stored in? (when in the car, I mean,
not at the petrol station).

A tank that is *very* well protected against being ruptured in a
collision (hydrogen is highly explosive - R101, Hindenberg etc) and with
*very* good seals to prevent it leaking out of the joints in the pipes
between the tank and the engine (hydrogen is the smallest of all
molecules and can escape through gaps that bigger molecules can't get
through).

I'm not sure how much hydrogen a tank can hold, in terms of mass of
hydrogen or range of car, if it is roughly the same size as a
petrol/diesel tank to fit in the same space under the rear seats.

Hydrogen has very high energy density -
https://www.energy.gov/eere/fuelcells/hydrogen-storage says about 120
MJ/kg, compared with about 45 MJ/kg for petrol or diesel (I was
surprised that there was very little difference between the figures for
petrol and diesel).

Partly true..

"On a volume basis, however, the situation is reversed; liquid hydrogen
has a density of 8 MJ/L whereas gasoline has a density of 32 MJ/L,"

So your tank needs to be a lot bigger and that assumes liquid hydrogen
not compressed gas.