The earth promises many power sources. Just like the geothermal and solar energy, which have long been used in heating homes and lighting as well when harnessed. Even in the last century these forms of energy was in use. Due to massive size of oceans, this energy can be used on much wider scale than other alternative sources of energy. The waves produced by the ocean and tides that hit the sea shore has enormous potential in them. If they are harnessed with full capacity they can go a long way in reducing world’s energy problems.
It probably will, with the increased global efforts towards using renewable energy sources. Water is everywhere and is huge, using it as power would be smart. However, water isn't very renewable. We cannot make water out of nothing, and the ocean levels can drop. Sunlight will be around for as long as the sun is, and the winds will exist as long as there exist different temperatures, but water can dry up and just disappear for good. It will become a renewable energy source, but isn't really that renewable.
I feel that since wave energy is already being tested and successfully so in many applications, it is destined to become a viable renewable energy source. While it is still in its early development phase, my opinion is that it will succeed and should be taken seriously. We are already relying on wind and solar energy; what is so different with water power?
I wish that ocean water could be used as a renewable energy source, especially because I live about 10 miles from the ocean in Florida! We desperately need new forms of renewable energy. However, I don't believe that the technology is there yet to turn ocean water into energy. It won't happen in the next decade at least.