Class 799 hydrogen flex trains...

[hooverboy]

I suspect that for road vehicles hydrogen power may very well catch on: the question is whether the same arguments translate to the rail sector. I also note that progress continues to be made with the development of hydrogen powered trains and there seems to be growing political enthusiasm for the concept: I'm not sure the same can be said for battery power.

I think the same can CERTAINLY be said for battery power.
Improvement of Energy storage is the holy grail.We're seeing it obviously in automotive,cars,trucks and so on., but also domestically in things like tesla powerwall.
The technology is still not as advanced as it needs to be, but with fossil fuel costs rising there will be a demand for bigger and better batteries with better "range", higher output, better environmental/temperature stability and more cycles between failure- I would expect the road haulage sector to be all over this once the product improves and the costs come down a bit.

Likewise I think rail will adopt it,but will be a bit slower off the blocks,

I'm still not convinced hydrogen is the be all and end all though. Just from a purely chemistry perspective the calorific value of hydrogen is tiny compared to NG, and you have other issues like pressurisation which would mean going a small leak in a traditional NG system shooting out a plume of flame, to something potentially catastrophic and explosive blow out for a H2 system, given the much higher BAR the fuel is stored and transmitted at,

 

[hooverboy]

Just watching an piece on BBC News right now. It is moving, which is good news. The bad news is that the fuel, generation units and batteries are inside the unit rather than underneath. That will be the real challenge and when they can move the kit under the floors might the 799 project move forward. However like other concept trains being tested with older vehicles, I suspect that any lessons learnt from these kinds of tests will ultimately be best purposed in new units, built specifically to accommodate the fuel and conversion requirements.

they wouldn't have it underneath the unit in the case of hydrogen.
H2 being lighter than air, they would store it on the roof somewhere, so theoretically any gas leak would go upwards into the atmosphere, not the cabin.

 

[hooverboy]

Greater Anglia's new FLIRT 3 and 4 car trains have power units above floor level in the form of the short mid-train power module, so presumably a similar solution could be used if it proves too problematic to fit all the kit below floor level?

I would expect so.
It's quite a neat design,and I think those power packs could well be very versatile with different power generation modes.

perhaps something ROSCO's should bear in mind when the sprinters are due replacement.
I very much like the 755's, stadler have done a nice job on them, and I would be quite pleased to have something like these as a whole fleet replacement for 15x(just add end gangways and proper size fuel tanks)