Science

...electrolysis.

If one enters the words electrolysis and seawater into Google Scholar, one gets over 40,000 hits.

I have been impressed by a few of the papers, notably the work of Dr. Heather Wilauer, using selective ion membranes to electrolytically obtain hydrogen and carbon dioxide from seawater simultaneously for use in FT synthesis.

In a wise future I see electricity as a side product of other industrial heat driven processes and in cases where excess electricity is available beyond grid demand, such a process might be worth pursuing.

Until electricity is "green" electrolysis isn't. Regrettably humanity is pursuing fantasies that don't work very well to pretend that electricity already is green. It's tragic, but thankfully there are people who have embraced reality. They may not triumph, but they exist.