This is sarcasm right? Hydrogen isn't a source of energy its a storage mechanism that has to be produced using fossil fuels or electricity, and you don't get more energy out of it than it takes to produce it.
Carbon is one such atom.
https://old.reddit.com/r/energy/comments/22gryt/seawater_pow...
https://old.reddit.com/r/dredmorbius/comments/22k71x/us_navy...
Fischer-Tropsh (creating synthetic analogues of petrol, kerosene/jet fuel, or diesel), or Sabatier process (creating alcohol) are two options.
Yes, it's a net energy sink. You're trading cheap surplus electricity for high-density, long-term storable, stable, dispatchable thermal fuel.
You can store hydrogen in underground salt caverns. We could store years' worth of energy demand.