"NY" wrote in message
o.uk...
"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)

Not convinced that that is necessary with compressed hydrogen
in a cylinder, it should be fine in a collision tho the design may
well need to avoid it wrecking the humans.

And hydrides dont have that problem at all.

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).

Yeah, tho that seems to be pretty easy with the
few hydrogen powered buses that are around etc.

I'm not sure how much hydrogen a tank can hold, in terms of mass of
hydrogen or range of car,

Likely that isnt great given that its mostly buses using it
currently, presumably due to the size and weight of the tank.

if it is roughly the same size as a petrol/diesel tank to fit in the same
space under the rear seats.

Cant see that being feasible, particularly with the
much thicker walls needed for compressed hydrogen.

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).

The difference comes from the more effective extraction of that
energy with diesel due to the different combustion temps and
pressures. But those also produce much worse pollution too.