The Scotrenewables tidal turbine (SRTT) system is an innovative free-floating rotor-based tidal current energy converter, which has been under development for over three years. The design has won various awards, including an Enterprise Fellowship - awarded by the Royal Society of Edinburgh, and Scottish Enterprise. In April 2006, the design won the inaugural Shell Springboard competition.

The concept in its present configuration involves dual counter-rotating horizontal-axis rotors driving generators within sub-surface nacelles, each suspended from separate keel and rotor arm sections attached to a single surface-piercing cylindrical buoyancy tube. The device is anchored to the seabed via a novel mooring attachment and compliant mooring system. A separate flexible power and control umbilical then connects to a subsea junction box. The rotor arm sections are hinged to allow each two-bladed rotor to be retracted so as to be parallel with the longitudinal axis of the buoyancy tube, giving the system a transport draught of under 4.5m at full-scale to facilitate towing the device into harbours for major maintenance. 

Designed above all for access and maintenance, the free-floating SRTT combines many of the design principles used in the offshore and wave energy industries and much of the existing technology from the wind energy industry. Some of these key principles include a focus on survivability, use of existing proven equipment, standardisation of components, off-site maintenance and quick mooring and electrical connection and disconnection using modest vessels.

Specifically designed also for low-maintenance and economic efficiency, the Scotrenewables Tidal Turbine concept incorporates the key design principles of minimisation of component numbers and use of existing proven technology. This enables a fast and relatively low risk route to commercialisation, and clearly puts the SRTT concept in a strong position ahead of many of its competitors.