On 14/08/2019 12:18, The Natural Philosopher wrote:
On 13/08/2019 23:37, John Rumm wrote:
Indeed, although while hydrogen fuel cycle efficiency is horrid[1], it
does have some quite attractive aspects that allows it to be used and
deployed in much the same way and with similar infrastructure as used
for petrol/diesel - quick refilling, bulk road/rail distribution as
well as manufacture on site.

No. NONE of those things are in any way simiar to carbon based fuels.
It is te smallest atom you can get.
It leak through the smallest of holes

But not that fast through metal piping and metal to metal joints. Until
we had carbon canisters and sealed petrol tank lids, we lost fuel duel
to evaporation too.

It is highly explosive.
It has a very low flashpoint

Yes. However, the tanks used have little chance of leaks and the fuel
cell could presumably be mounted with the tank to minimise joints and
potential movement. If it leaks, it rapidly disperses, whereas petrol
has a fairly immobile and highly explosive vapour bubble around any leak.

It needs to be kept under pressure.
It chills when it expands

As for any liquified gas - although Hydrogen is harder.

It is extremly low energ dnsity by VOLUME so nees massive tanks.

From the charts I have just looked at, petrol is about 3.4 times better
than Hydrogen - however, a Hydrogen fuel cell and electric motors are
about 2.6 times as efficient as a petrol engine ... so the difference is
not huge.

It only makes any sense with abundant nuclear generating capacity
obviously.

It doesnt make sense even then. Kerosene level hydrocarbons are like
lithium based batteries. They are at the top of the curve between good
and bad compromise.

It does make sense, as a "clean" fuel that due to the efficiencies is
not much worse than petrol per unit volume.

In terms of energy per unit VOLUME, nice balance between utility and
safety, cleanlisness of burn, they are all 'about right'

Nuclear power shpuld MAKE 'fossil' fuel....

While that would solve the supply of fuel and, done right, be close to
CO2 neutral, it would still produce many of the airborne pollutants that
we would be better without.

SteveW