Could the short HSTs be converted to hydrogen or battery operation?

[Elecman]

Wow! Thats somewhat optimistic considering how far down the priority list this line would be and the current rate of electrification!

I didn’t say anything about scheme priorities, I merely suggested that it’s could be done in 5 years with things lined up a proper rolling program And all necessary approvals an£ designs completed, but you would need to allow for any prolonged National Grid Timescales for the necessary Grid Supply Points

 

[Domh245]

Good point - need a fair amount of spare ‘space‘ for the regeneration slowing into a stop then all the fuel cell power generated during the stop. But still presumably a lot less than needed to power the train for tens of miles??
Though do you actually have to have the fuel cell at full power the whole time? I assumed it was a 100%/0% situation where you could still turn it off and on for stations etc.
If you can’t stop/start it would you need some kind of auxiliary power, so that you don’t have a full size fuel cell going full whack from the moment you switch the train on?

Not necessarily full power, but there is a peak efficiency point of a fuel cell usually quite a way of it's notional peak power. It's better to let the fuel cell sit at that point and just churn out x watts constantly than trying to vary it up and down to meet the exact demand - the instantaneous response (and storage function) of a battery is far better suited for that. The auxiliary power to start a fuel cell comes from the battery, and it's also worth noting that there is a point where the power the fuel cell generates becomes so low that you're better to turn it off (the fuel cell requires a certain amount of power to operate it's 'balance of plant' - compressors, condensers, cooling etc)

As for 'do you have to run it at full power all the time' - that depends on the fuel cell you use and the duty cycle you're running it on. The ideal would be to size the battery and fuel cell such that you could run it constantly at a low, but efficient power so that you never quite run out of battery at the worst point of a duty cycle (eg just climbed a gradient from stationary and are about to brake to a stop again downhill). There's no reason why you couldn't turn it on and off as necessary when the battery nears full, but the most efficient system is one that isn't so big that you carry around extra weight/cooling requirements for it to sit off half the time, nor one that's so small you have to run it harder than peak efficiency and loose range (or leaves you stranded without enough power!).

Also don't forget that as the fuel cell's only operating emission is water, there's no reason to turn it on and off as you go through stations or urban areas!

 

[Meerkat]

Not necessarily full power, but there is a peak efficiency point of a fuel cell usually quite a way of it's notional peak power. It's better to let the fuel cell sit at that point and just churn out x watts constantly than trying to vary it up and down to meet the exact demand - the instantaneous response (and storage function) of a battery is far better suited for that. The auxiliary power to start a fuel cell comes from the battery, and it's also worth noting that there is a point where the power the fuel cell generates becomes so low that you're better to turn it off (the fuel cell requires a certain amount of power to operate it's 'balance of plant' - compressors, condensers, cooling etc)

As for 'do you have to run it at full power all the time' - that depends on the fuel cell you use and the duty cycle you're running it on. The ideal would be to size the battery and fuel cell such that you could run it constantly at a low, but efficient power so that you never quite run out of battery at the worst point of a duty cycle (eg just climbed a gradient from stationary and are about to brake to a stop again downhill). There's no reason why you couldn't turn it on and off as necessary when the battery nears full, but the most efficient system is one that isn't so big that you carry around extra weight/cooling requirements for it to sit off half the time, nor one that's so small you have to run it harder than peak efficiency and loose range (or leaves you stranded without enough power!).

Also don't forget that as the fuel cell's only operating emission is water, there's no reason to turn it on and off as you go through stations or urban areas!

Interesting stuff thanks. So you don’t need that much battery buffer as you can turn the fuel cell off when it’s full. Is there any cost to turning it off and on - ie the comment about diesels not liking being turned off and on (though there are plenty of stop/start diesel cars rattling about)

 

[Domh245]

Interesting stuff thanks. So you don’t need that much battery buffer as you can turn the fuel cell off when it’s full. Is there any cost to turning it off and on - ie the comment about diesels not liking being turned off and on (though there are plenty of stop/start diesel cars rattling about)

There's no moving parts in a fuel cell so unlike a diesel engine stopping & starting it when cold will cause excessive wear, there's no real penalty for starting it 'cold' that I'm aware of other than a drop in efficiency at cooler temperatures and through operating it away from it's peak point, though I will admit to only having a surface level understanding of Fuel Cells!

With stop/start cars of any fuel type, it should only start working once the engine is up to temperature to avoid damage. This takes several minutes with a small car engine, and quite a bit longer for a high displacement rail engine!

 

[gingerheid]

Is it just me that thinks Hydrogen is awful explosive to be used as a fuel?

 

[Bletchleyite]

Is it just me that thinks Hydrogen is awful explosive to be used as a fuel?

Petrol goes bang quite nicely too, yet we use that?

 

[gingerheid]

Petrol goes bang quite nicely too, yet we use that?

I think hydrogen is about 10 times more explosive?

 

[Bletchleyite]

I think hydrogen is about 10 times more explosive?

Though if released it goes straight up in the air and disperses, unlike petrol.

 

[Starmill]

The main danger with Hydrogen is an explosive reaction, rather than a flammable one with petrol. Whether you consider one more dangerous or better mitigated than another is a slightly different question.

The problem with Hydrogen as a 'fuel' (some experts would argue it is not actually a fuel) is the inefficiency of actually producing and storing it.

It would be far more cost effective and cut carbon to simply close the railways that cannot be electrified, and replace them during the 2030s with a network of electric minibuses. Battery electric trains are probably our only hope. We really have screwed this one up electrification wise though, road traffic will be electrified at a faster rate than rail within a few years.

 

[Bletchleyite]

The main danger with Hydrogen is an explosive reaction, rather than a flammable one with petrol. Whether you consider one more dangerous or better mitigated than another is a slightly different question.

Petrol vapour also explodes, to be fair. It's diesel that just burns (and if you chuck a match in it it would go out - you need it to be vaporised to burn).

 

[92002]

Wow! Thats somewhat optimistic considering how far down the priority list this line would be and the current rate of electrification!

Maybe they should just make the power car into a hybrid. Put a pantograph on the roof and a transformer in the guards van. With a smaller Euro 6 Engine and batteries. No need for the current big diesel for a smaller train.