Installation and Removal

Tow-out

The advantage of buoyant designs is that they can be floated into place, removing the need for craneage and barges which are impractical in the tidal flows found in waters such as the Pentland Firth. With the Triton platform no cranes, barges, jack-up rigs or divers are required for any part of the operation - only a workboat with moderate lift capabilities.

A workboat tows theTriton into position into the prevailing current

For transportation, the swinging arm of the platform is stowed between the main spar buoys so that the turbine can be towed into position with minimum draft. The spar buoys comprising the main body of the TidalStream platform are at full buoyancy for float-out. The gravity base in the images below has been pre-installed on the seabed and is marked by a guide wire and buoy.

The Deployment Sequence

The base has been pre-installed with electrical cables in place. This base is either a piled structure or, if as in the Pentland Firth the seabed is too rocky to allow this, a gravity base consisting of a flooded concrete caisson - as shown below - or a tray that is filled with rock ballast once in position. The base is equipped with a guide wire and stabbing pin to accept the swivel ring at the end of the SST swinging arm.

Removal is simply a reversal of the above procedure with ballast water being pumped out of the spar buoys

The SST is brought into place over the guide wire

Initial installation

The swinging arm is lowered down the guide wire and electrical cabling (not shown)

The swivel ring fits over the stabbing guide and is locked in place. The  swing arm is locked and the cable connections made. The platform is now in its maintenance position and ready for first stage commissioning

Transition to operation

For the turbines to assume their operating position, water ballast is admitted into the main spar buoy causing it to start to sink down in the water

As the ballast water is added the SST continues to sink rolling around to the upright operating position

Finally, the platform ends up its operating position. With the rotors stopped and only static thrust on them, the turbines ride a few metres higher than they do when running and with full thrust on the rotors

TRITON

The most powerful tidal current energy generator now in development - 10MW from a single installation

TidalStream have now completed successful testing of a six-rotor scale prototype of Triton demonstrating its versatility, stability, and opportunities for easy access and maintenance