[seafarer]

Well, many people still think hydrogen is the ultimate answer. This despite the fact that most of hydrogen (in NA at least) is extracted from Natural Gas, using electricity that comes primarily from coal and oil fired generating plants. Even if you do use sea water, the energy to extract hydrogen has to come from somewhere, and that almost assuredly means electricity demand.

There is no free lunch when it comes to energy. Every form of energy we have or are working on has some costs (environmental, social, economic, whatever) that come with it. The thing is we've just been blissfully ignorant of having to face the costs, but now the crunch is here.