They don’t mention whether it takes more energy than it produces.
And I’m betting IT DOES.
It's a first law of thermodynamics certainty that it takes more energy than it produces.
The only thing this might be useful for is to store energy from intermittent sources such as wind and solar in the form of hydrogen for future use.
It would be pointless to use fossil fuel electricity for this process, unless the hydrogen itself is the desirable end product for use in hydrogen-fueled vehicles. But even then, it is more efficient to derive hydrogen from natural gas than it is from the electrolysis of sea water.