Obviously no one would hope that a disaster would happen like...

Obviously no one would hope that a disaster would happen like this again, but a bit of thought into the construction of a grid with decentralised infrastructure would make it possible for Bluegens to be operated in the event of mains failure if the gas supply was intact. Isolation of affected area and connection of a generator to give mains supply, with fuel cells holding most of the load should be possible.
Not the most ideal situation, but during such events, life as close as possible to normality would provide some heartening relief for those affected.