Tidal stream power technology - state of the art

Free-stream tidal currents, such as those in the Alderney Race and the Fall of Warness, represent a potentially plentiful and reliable source of clean energy. This paper seeks to describe the state of the art of tidal stream power technology. There is wide variety across the range of devices under development and, although the majority of concepts utilise a horizontal axis rotational method of generation, there is no sign as yet that the industry is near convergence towards a single configuration. There are, however, several clear trends emerging in technology and these are identified. A brief summary is given as to the perceived advantages and drawbacks of each of these. The current study found over forty different companies with tidal stream generation technologies under development and there was a wide variety of concept across the range of devices. In places there was a clear influence from the wind industry, with many companies developing two-or three-bladed, high aspect ratio rotors very similar to wind turbines. There were also clear divergences from the wind turbine pattern, with ducted devices in particular forming a large proportion of the devices found. Finally, an overview of the projected timescales for technology deployment for the industry as a whole and the main players are outlined.