Two-blade turbines are at the cutting edge

Oslo: Morild is a floating, moored construction based on the same principle as conventional wind turbines.

The device weighs 300 tonnes and covers an area of 35 square metres. Its weight sinks the device down so that the turbine operates between two and 25 metres under water.

It has four two-blade turbines with a diameter of 23 metres each that utilise the energy potential in tidal and ocean currents. The only part visible above water will be the small control tower on the top.

When maintenance work needs to be done, its 300 tonnes of water ballast are pumped out and the plant is brought to the surface.

Morild is easy to relocate and can be towed by boat. Its mooring employs known anchoring technology in tidal areas, and suction anchors at deeper ocean sites. The vertical force on the machineis eliminated by its patented buoyancy system.

Morild's turbines send the power to two standard synchronous generators via hydraulic transmission.

The device is highly efficient because it can be operated with varying revolutions per minute (RPM) on the turbine and constant RPM on the generators. The turbines can also be turned 180 degrees to use energy in both directions. High efficiency is obtained through contra-rotation of the turbines.

A 22-kilovolt electricity cable runs from the transformer to shore, and an underground cable connects it to the grid.