State of the art for tidal currents electric energy resources

Renewable energy is an effective and clean source of supplying electrical loads especially in remote and rural areas. In this paper we discuss tidal in-stream energy as it relies on the same technologies developed from offshore wind turbines for generating electricity at offshore sites. In particular, we survey the tidal in-stream technologies, challenging issues, various types of generators, their dynamic modeling, grid integration performance, and finally the new research issues.