The question of whether to back hydrogen power or batteries is perhaps the singularly biggest transport power question we face and has been a hot potato for quite a few years. Both have advocates and strong arguments. Traditionally the big argument in favour of hydrogen fuel cells (personally I just don't see using hydrogen in internal combustion engines as being sensible) has been suitability for long range via normal re-fuelling in combination with the fact that batteries rely on rare metals and their manufacture and recycling can be problematic in environmental terms. Against that, hydrogen isn't exactly a clean fuel if sourced from a hydrocarbon feedstock in an energy intensive process (and people sometimes get carried away with their view of just how much renewable electricity we currently have), battery chemistry (leading to higher energy density, longer range, less reliance of hard to obtain metals) seems to be advancing rapidly and safe storage and use of hydrogen does present certain issues. Some of the risk management issues can be addressed by using hydrogen carriers and reforming.
My own view is still leaning more towards batteries, but that's just my opinion.
That would be true, as regards the green credentials of hydrogen extraction, if that was the intention.
But AFAIK, it is not. Germany (or Alstom initially) are developing hydrogen extraction plants powered by wind turbines, and Alstom in the UK appears to be developing a relationship with a petro-chemical company who produce chlorine gas in the North West and also Teeside, a by-product of which is hydrogen, currently going to waste. Whilst the production of chlorine itself is not necessarily a green process (I have no idea) the fact that it is being done anyway and that the waste product can become a useful fuel, is certainly carbon neutral. Meanwhile Alstom have their own hydrogen production facility near their works, also in the North West. I understand, from Rail Europe, that Germany are seeking similar arrangements in the longer term.
Also in favour of hydrogen is that re-fuelling (of the iLent anyway) takes only 15 minutes, giving a range of some 800Km for that 2 car Coradia - not sure what is being claimed exactly for the 4 car 321 conversion, but I think 450 miles was mentioned somewhere? The range and refuelling time is somewhat superior to current Tesla technology (which appears to have hit a bit of a brick wall on further efficiency at the moment, after the Australian solar farm experiment demonstrating enhanced charge retention). In the short term therefore, pending further step changes in battery power technology and useability, the H has it, IMHO.