I'm useless at science but almost everyone knows the chemical formula for water. And, with global warming leading to rising sea levels, there's increasingly too much seawater. So I wondered what progress was being made towards making hydrogen from seawater - and there have been encouraging studies, although whether the methods they've developed can be scaled up to industrial production levels is another matter. It sounds like a better approach than making 'blue hydrogen' from gas, though.
See what you think of these ideas: