With the increasing concern of global warming, the importance of reducing greenhouse gas emissions has been accepted worldwide. Realizing the contribution of conventional energy sources to greenhouse gas emissions and the increasing demand for energy, the harnessing of renewable energy is becoming an important issue in our time. As a renewable source, tidal energy is coming into consideration recently because of its long term predictability and large potential. In this paper, the existing tidal energy harnessing systems are reviewed and the challenges and practical solutions for each basic structure of the tidal harnessing system are compared and discussed. The Gulf Stream and North Carolina tidal water properties are investigated. Based on the review and discussion of existing devices, suitable harnessing devices for Gulf Stream and North Carolina tidal water are proposed.