The authors of an article in a recent issue of Oceanus (22, Winter, 1979/1980) say that
…rivers flowing into the sea could provide enough salinity-gradient power to meet 10 percent of present global demands. There is fifty times more energy in the Florida Current than in all the rivers of the world. OTEC, the most publicized experiment in ocean energy (the acronym stands for ocean thermal energy conversion), is thought by its supporters capable ultimately of equalling something on the order of a third of present installed electric capacity in this country. The wave energy flux along a hundred kilometers of the most promising coasts translates into the output of a large generating plant. An all-out wind conversion program along our coasts could produce more than a billion kilowatt-hours annually within twenty years. If the long life of most tidal facilities is taken into account, tidal power probably is economically competitive with other forms of generation right now. Marine biomass may become an important source of fuel and food, and breakthroughs in our knowledge of chemosynthesis and other bacterial activity may open even wider horizons.