Researchers have worked on deriving energy from both ocean currents and ocean waves, but I am unaware of any way to get energy out of salt water per se. In fact, it takes a great deal of energy to desalinate water so that one can drink it. I've posted 2 government websites that cover the two types of energy sources from the oceans currently being investigated. Good luck with your project.
You can simply google the best and most visited sites. Surely it also depends on what kind of alternative energy you are researching. If you are making a school or a college project it's probably smart to include general information about alternative energy. Here is a nice article that might help you: