Hydroflex - testing

[Philip Phlopp]

I'd take diesel over hydrogen any day. Remember Hindenburg?

In which the skin of the airship was more flammable than the hydrogen.

 

[birchesgreen]

I'd take diesel over hydrogen any day. Remember Hindenburg?

I suspect technology may have moved on a tad from the late 1930s.

 

[Bald Rick]

I'd take diesel over hydrogen any day. Remember Hindenburg?

Remember Buncefield?

 

[102 fan]

I suspect technology may have moved on a tad from the late 1930s.

I must of missed school the day they taught about how less combustible hydrogen was.

 

[MotCO]

And wowing about 50mph - what year is it again?

Do many diesel metro trains run faster than 50 mph? If not, hydrogen would be a cleaner alternative to dmus, but I would be concerned about any risk of explosion in a built up urban area, i.e. where metro trains run.

 

[102 fan]

Remember Buncefield?

Are you trying to say that hydrogen isn't as combustible? This is a typical green initiative, looks fine and dandy on paper, put practicality is lacking.

Do many diesel metro trains run faster than 50 mph? If not, hydrogen would be a cleaner alternative to dmus, but I would be concerned about any risk of explosion in a built up urban area, i.e. where metro trains run.

Apparently, according to some here, it's not the nasty hydrogen of 80 years ago, but a much more friendly version that will rise up and ignite out of harms way.....

 

[Bald Rick]

Are you trying to say that hydrogen isn't as combustible? This is a typical green initiative, looks fine and dandy on paper, put practicality is lacking.

Not at all.

What I’m trying to say (not very well), is that in the unlikely event of an incident with a train that has hydrogen tanks, that causes the tanks to rupture, the hydrogen is likely to head upwards, fairly rapidly. Therefore the risk of ignition and subsequent conflagration of the incident itself are less than...

In similar incident with a diesel train, the diesel ends up all around you, and stays there. I have attended a train collision with diesel all over the floor, which needed the rapid attention of the fire service, even though there was no fire.

 

[GRALISTAIR]

For a moment I thought this was a comment made by GRALISTAIR!
Sensible idea though.

Yes I would have been proud of that comment!

 

[edwin_m]

A fuel is a store of energy. Under certain circumstances that energy may be released uncontrollably. The source of the fire at Carmont was almost certainly the fuel in the power car tank, which would probably have been ruptured by the derailment and spread diesel onto the coaches behind (as has happened in several other accidents).

Hydrogen probably stores less energy per train and it's likely to be shared amongst several tanks so the amount of energy at risk of being released is probably less in most accident scenarios. As mentioned it is much lighter than air and dissipates upwards from any breach, unless in a constrained environment. Probably the most dangerous fuel is LPG, because it's a gas so invisible but also heavier than air, so tends to pool at low points where it can reach explosive concentrations.

 

[Domh245]

What I’m trying to say (not very well), is that in the unlikely event of an incident with a train that has hydrogen tanks, that causes the tanks to rupture, the hydrogen is likely to head upwards, fairly rapidly. Therefore the risk of ignition and subsequent conflagration of the incident itself are less than...

On that vein as well, worth bearing in mind that a diesel tank is a few mm of steel (at worst, kevlar bladders at best but on the rail industry I'm guessing it's much nearer the former than the latter), whilst a hydrogen tank will typically be significantly thicker (not least to withstand the pressures) and typically of a much more advanced construction to withstand punctures.

 

[Meerkat]

Not at all.

What I’m trying to say (not very well), is that in the unlikely event of an incident with a train that has hydrogen tanks, that causes the tanks to rupture, the hydrogen is likely to head upwards, fairly rapidly. Therefore the risk of ignition and subsequent conflagration of the incident itself are less than...

In similar incident with a diesel train, the diesel ends up all around you, and stays there. I have attended a train collision with diesel all over the floor, which needed the rapid attention of the fire service, even though there was no fire.

How do you mitigate the risk in tunnels and stations, noting that those environments might have OLE and other electrics when the hydrogen train gets to the populated end of the line?

 

[102 fan]

How do you mitigate the risk in tunnels and stations, noting that those environments might have OLE and other electrics when the hydrogen train gets to the populated end of the line?

It's greener, so that aspect will be ignored.

 

[Philip Phlopp]

On that vein as well, worth bearing in mind that a diesel tank is a few mm of steel (at worst, kevlar bladders at best but on the rail industry I'm guessing it's much nearer the former than the latter), whilst a hydrogen tank will typically be significantly thicker (not least to withstand the pressures) and typically of a much more advanced construction to withstand punctures.

Yes - they'll be using compressed gas cylinders, probably 350bar and manifolded into a pressure regulator which will reduce the hydrogen flow to just above atmospheric pressure. The kinetic energy in a single tank, and we'll be talking several here, is comparable to several kg of high explosive. That's ignoring the chemical energy in the hydrogen when it combusts. There's typically a lot of pipework that can leak too, oh, and did we mention that hydrogen has this annoying habit of burning with an virtually invisible light blue to clear flame ?

How do you mitigate the risk in tunnels and stations, noting that those environments might have OLE and other electrics when the hydrogen train gets to the populated end of the line?

Hydrogen doesn't conduct electricity, so shouldn't cause any flashover events when coming into contact with OLE at high concentrations.

 

[Bald Rick]

Just to clarify, I’m not a hydrogen champion! OLE and batteries all the way for me. (Probably more of the latter than most people would prefer, but then I’m visionary )

 

[Meerkat]

Yes - they'll be using compressed gas cylinders, probably 350bar and manifolded into a pressure regulator which will reduce the hydrogen flow to just above atmospheric pressure. The kinetic energy in a single tank, and we'll be talking several here, is comparable to several kg of high explosive. That's ignoring the chemical energy in the hydrogen when it combusts. There's typically a lot of pipework that can leak too, oh, and did we mention that hydrogen has this annoying habit of burning with an virtually invisible light blue to clear flame ?



Hydrogen doesn't conduct electricity, so shouldn't cause any flashover events when coming into contact with OLE at high concentrations.

How does hydrogen stuff fail - split and gas spurt, or a dangerous shrapnel burst and gas cloud?
I was thinking more about sparks caused by OLE. Obviously we are talking fringe events - gas leak...in a tunnel/station...under OLE.....with an adjacent train sparking the wire - but rail safety seems to account for some pretty fringe events.

 

[js1000]

The Hydroflex has so much potential and it is a great step for decarbonisation.

But then you look at the class 769s and how long the delays with the engines took. How much more with the new hydrogen equipment.

Doesn't look promising production wise

The 769s have been ridiculous. To think the order was placed in December 2016. Often refurbishing something is always more complicated than simply starting again.

The 319s are hardly the most reliable of units so don't see how strapping engines on it is going to improve that. These bi-mode "conversions" to diesel/battery/hydrogen have to be taken with a pinch of salt until they are proven when in service.

 

[Philip Phlopp]

How does hydrogen stuff fail - split and gas spurt, or a dangerous shrapnel burst and gas cloud?
I was thinking more about sparks caused by OLE. Obviously we are talking fringe events - gas leak...in a tunnel/station...under OLE.....with an adjacent train sparking the wire - but rail safety seems to account for some pretty fringe events.

It depends what fails - if the cylinder lets go during recharging, as an educated guess, I'd say it would destroy most of the carriage (even without an explosion) unless you've got a Kevlar jacket and significant mechanical protection in place to restrain the shrapnel. If it's a hose or pipe failure, they'll likely vibrate and fail, you just have to hope you don't get a fire from the leak.

 

[BayPaul]

I'd take diesel over hydrogen any day. Remember Hindenburg?

I think if Hindenburg had been full of diesel it would have been just as flammable, though perhaps not as good as flying

 

[Deepgreen]

Another issue is that hydrogen's production process is very 'un-green' - it requires fossil fuels to produce it. It may be cleaner at point of use but is still very polluting in the round.

I think if Hindenburg had been full of diesel it would have been just as flammable, though perhaps not as good as flying

Indeed - perhaps a jacket of some malleable metal might have helped, but then it would have gone down like a lead...

 

[birchesgreen]

I must of missed school the day they taught about how less combustible hydrogen was.

I must have missed school they taught how trains are made from flammable fabric.

 

[AY1975]

Are these units testing something that's substantially different from the German entirely newbuild units that seem to be already in service, or nearly in service? Because at first sight, it seems like it's a technology that's already been developed further elsewhere.

I'm guessing that the HydroFLEX needs a whole coach interior taken up by the hydrogen fuel cells because it's a converted EMU, whereas the Coradia iLint is a purpose-built hydrogen powered train.

It will be interesting to see whether the Class 321 "Breeze" units also have a whole coach interior taken up by the fuel cells: I understand that Alstom plans to draw on its experience from the iLint for the "Breeze" project, although obviously these will also be converted from conventional EMUs.

 

[norbitonflyer]

I think if Hindenburg had been full of diesel it would have been just as flammable, though perhaps not as good as flying

The Hindenburg was full of diesel - that's what powered the motors. (Although as it crashed at the end of the transatlantic flight the tanks were fairly empty). And yes indeed, it was the waterproofing of the canvas that burned for longest. (Adequate waterproofing was a lesson learned from the R101, which crashed after becoming waterlogged, but the coating material used, aluminum-impregnated cellulose acetate butyrate, was itself flammable )

As air disasters go, the survival rate of the Hindenburg crash was fairly good at 64% (23/36 passengers, 39/61 crew).

 

[birchesgreen]

I'm guessing that the HydroFLEX needs a whole coach interior taken up by the hydrogen fuel cells because it's a converted EMU, whereas the Coradia iLint is a purpose-built hydrogen powered train.

It will be interesting to see whether the Class 321 "Breeze" units also have a whole coach interior taken up by the fuel cells: I understand that Alstom plans to draw on its experience from the iLint for the "Breeze" project, although obviously these will also be converted from conventional EMUs.

The greater loading gauge on the Continent means fuel cells can be stored above the passenger cabin perhaps?

 

[Domh245]

It will be interesting to see whether the Class 321 "Breeze" units also have a whole coach interior taken up by the fuel cells: I understand that Alstom plans to draw on its experience from the iLint for the "Breeze" project, although obviously these will also be converted from conventional EMUs.

~Half of each driving coach going by the renders (of a shortened train too, so to all intents and purposes a bit over 2 cars of passenger accommodation in the 3 car train)

 

[102 fan]

Why do some on here try to say that it wasn't hydrogen gas that was the cause of the Hindenburg fire? Is it because hydrogen is considered green and therefore immune from any criticism?

Would a BNFL nuclear cask type of experiment be possible? Just to reduce concerns that must be out there.

 

[Northhighland]

Hydrogen made from water using a complete renewable energy source like wind or tidal power is a sustainable environmentally friendly fuel source for the future. Unlike some sources of hydrogen currently in use made from hydrocarbons. https://thedriven.io/2020/07/08/hyundai-ships-first-fcev-heavy-duty-trucks-to-switzerland/ Hyundai have delivered the first Hydrogen powered trucks to Switzerland. This technology has a future. Battery trucks aren't really a viable options and for heavier duty diesel replacement Hydrogen offers considerable advantage.

Cant see any reason why rail would not embrace this technology. It would offer a way forward for many routes that will never be economic to electrify. Also from a personal point of view would rather see the HML with hydrogen powered trains than spoil the beauty with OLE.

 

[Deepgreen]

I must have missed school they taught how trains are made from flammable fabric.

No longer, but Quintinshill was an example of fuel (lighting oil) and further fuel (wooden coaches). These days, the most flammable part of many trains is the passengers.

 

[StephenHunter]

It's a demonstrator vehicle. There's a lot more work to do. Rome wasn't built or burnt in a day.

 

[Bald Rick]

Another issue is that hydrogen's production process is very 'un-green' - it requires fossil fuels to produce it. It may be cleaner at point of use but is still very polluting in the round.

Not if it is produced by electrolysis, and that electricity is from renewable sources.

Why do some on here try to say that it wasn't hydrogen gas that was the cause of the Hindenburg fire? Is it because hydrogen is considered green and therefore immune from any criticism?

I’m not sure anyone has said that...

 

[a_c_skinner]

Although it does burn (and explode) received wisdom is that it floats up and away and is safer. Don't ask received from whom.