While still needing to refuel every few weeks - as opposed to not requiring refueling for the life a nuclear vessel - it's better than the diesel-powered subs which require recharging the batteries after a few days. Obviously, it's loads cleaner than diesel power, not to mention lacking the eventual nuclear waste of the other alternative. Interestingly, because the operation of the hydrogen submarine is so quiet, it is virtually undetectable. It makes you glad that they are being open about the fact they have this new vessel, rather than letting us find out in a more unpleasant way.
In the last ten years, Air Products has built 70 hydrogen fueling stations for various uses across the world, laying claim to over 33,000 hydrogen refuelings thus far. They also have their fingers in the LNG (liquified natural gas) market as well.
[Source: Air Products]