Hydrogen pumps produce and store pressurised hydrogen in slow time. They don't produce it 'on demand' in the way you describe.
As hydrogen production through electrolysis is so inefficient, the best use for it that i've seen is from renewables when delivery exceeds demand.
Although on demand requires higher peak power loads, it doesn't incur the issue of storing large volumes of pressurised hydrogen, especially the H&S considerations that would likely be applied to facilities near residential areas. The 10,000PSI or greater pressure tanks are also very expensive, probably making cryogenic storage a better option. Local buffering storage would certainly ease delivery peaks, but would have to be significant to meet demands of a peak holiday period.
Electrolysis is not particularly inefficient as a "green" method of production, requiring 40% or so additional electrical energy input compared with the energy it contains plus compression overhead to get it to the 10,000PSI or so needed for tank filling. Other methods that don't involve cracking hydocarbons (supposedly accounting for 96% of current hydrogen production), would typically involve biomass cracking, but there are additional lifecycle considerations and energy inputs to obtain that biomass in a carbon neutral manner, overall a lot simpler to generate large volumes of electricity remotely and easier to deliver locally for electrolysis.
Lots of infrastructure issues to sort with mass hydrogen usage, as opposed to the current 17 stations in the UK, mostly single pumps it seems, (https://www.fleetnews.co.uk/fleet-management/future-fleet/high-hopes-for-hydrogen-electric-vehicles) to service 150 cars sold so far. A lot of catching up to do to meet the viability of BEVs, especially in the cost per mile area and meeting the purchase or lease price point of BEVs with similar performance.
Hydrogen production by electrolysis for use in vehicles is horrendously inefficient in comparison to using that energy to charge a battery that powers the vehicle directly.
The only way it makes sense environmentally is to use renewables to produce the electricity needed for that electrolysis. Even then you need a good reason for not just charging a battery. The best reason that I can see is remote locations with variable electricity generation from renewables. When generation exceeds demand use the excess to produce hydrogen.
Another good reason would be if we operated two types of vehicles, short range (BEV) and long range (hydrogen fuel cell). That way we wouldn't be wasting energy inefficiently powering vehicles via a wasteful method. Obvious oversimplification as it's not range but usage type that's really important but I'm sure everyone has already worked that part of it out anyway and usage type is too tedious to discuss.
I agree it is inefficient compared with BEVs and as I said it would have to be from electricity produced from renewables, doesn't make sense otherwise. The only advantages over BEVs is time to fill a tank vs battery charge and centralised refueling (which at present is a detriment due to lack of infrastructure, though), but if 450kW battery fast chargers are impemented in "filling stations", the advantages of hydrogen fuel cell vehicles disappear with fully battery charges in 15 mins.
If massive infrastructure changes are needed for both hydrogen fuel cell and battery electric vehicles, BEV seems to be quite a way in front at this point.
The basic freedom of movement which we taken for granted since we moved from either walking or riding horses is under threat. There are massive issues in the electrical infrastructure both in terms of distribution and generation needed to sustain the current level of movement if there is a 50% migration from fossil to battery. None of which I doubt our politicos or civil servants have even thought about.
But don't worry. The Brexit department can shortly change its priorities and focus on climate change for the UK , thus building on recent successes and securing continuous employment for all those strategic minded civil servants.
Its akin to soviet command economics. "Government set the policy, the beaurocracy delivers the structure, the people suffer the consequences".
IF globally we changed all petrol & Diesel engines to battery power using current technology I suspect we will run out of other minerals and materials required. Copper cobalt etc. Something has to give in this evolution of technology and that will almost certainly be escalation of costs of vehicles also, not just fuel, this will mean we all get shafted and most of us will need to rely on bikes or uber von tesla etc.... If we manage to get out of the house at all through the mountain of Amazon deliveries on the door step.
All I need is £140 000, just saw the electric porche on top gear what a motor ,, How about an electric seven ,, but linked to a speaker , linked to the throttle ,with the sound of a nice ford motor on twin Webber’s reving it’s nuts of
#8 ICE efficiency - Petrol = average of 30% Diesel = average of 35%
The Mercedes F1 engine broke the 50% efficiency barrier some time ago now we would all like one of those in a road going car!
Hi Geoff, those numbers are peak efficiencies when the engine is run at it's most thermally efficient point, which would only be applicable in a hybrid power train with the engine not directly attached to the wheels and run sporadically to charge a battery for a normal road car. Average efficiency with a conventional ICE drivetrain is quite a bit less, even 25% is a bit on the high side.
I beg to differ as your estimated % is well on the low side for modern ICE engines in cars. Peak efficiency in some modern bus & truck engines can peak near to 40%. There are even two strokes that exceed 50%.
But why quibble over the odd % here & there as there is more heat than light in all this!!.