Developments in large marine current turbine technologies - A review

Increasing concerns about environmental issues and depletion of fossil resources lead to a global need for producing more clean energy from renewable sources. For coastal areas or some remote islands, marine tidal current energy is a promising renewable power source due to its high predictability. During the last decades, prototypes of various horizontal and vertical axis marine current turbines (MCT) have been developed around the world. Although reviews on MCI's can be found in some state-of-the-art research papers in the last few years, many of the reported MCT projects were only at the planning/design stage when the papers were written. In fact, some projects do not have any further developments during the several years after their first reporting; and others have already upgraded their original designs and adopted up-scaled versions. In this paper, up-todate information on large tidal turbine projects over 500 kW is focused. The newest achievements of these large tidal current turbine technologies with their developing histories are presented. These technologies represent the industrial solutions for several pre-commercial MCT farm projects in the coming years. New developments in floating MCT technologies are also included. This paper provides a useful background for researchers in the tidal current energy domain and allows them to know the newest developments in large MCT projects around world.