The top fin controls the operational angle and stability of the Flumill System.The fin connects the two turbines and supports the upper bearings. Controlling the operational angle of the helix during operation (between 25 and 50 degrees), the fin has no moving parts, is buoyant and made from PVC foam with an outer composite material layer. The shape of the top fin will be optimized with respect to the sites
Counter rotating helixes and the natural adjustment of it’s operational angle according to the flow of the water ensures a low load on housing and the foundation. The outer edge of the helix will be restricted by the speed of the water, thus creating no harm to marine fauna. The design gives low turbulence and no cavitation. While the shafts, ball bearings and pivot system are to be made in steel, the dual helixes will be made in composite material due to durability, strength and relatively low cost.
Generator and housing
The housing is a watertight compartment for the generator and other equipment. The Housing will in addition to house equipment also provide structural strength and support for pivot bearing and turbine shaft bearing. The generator will be made by an OEM (Original equipment manufacturer) based on standard subsea solutions. The generator will be constructed on the same principles as the generator used by previous Tidal Systems.
Foundation and assembly
The foundation consists of a steel structure attached to the seabed using predrilled piles or a gravity base structure. The choice of method will depend on the seabed conditions
The foundation will be attached to the seabed before installing the Flumill system using monopile or predrilled piles.
Cabling will also be connected towards this structure. The Flumill system has a pivot frame that locks to the
Testing and simulations
The Flumill system has gone through a multitude of CFD simulations as well as extensive tank, tow and pilot tests. The CFD simulations were performed by two separate and independant facilities, using different software. Tests were corresponding. Flumill has also carried out successful tow testing performed over two weeks in 2011, and succesful EMEC testing (European Marine Energy Centre, Orkney Island) Sep. 2011 – Jan. 2012 (image below).
After the extensive testing just completed, Flumill’s next step is to deploy a fullscale pilot in Rystraumen, near Tromsoe in northern Norway. The pilot will be deployed with grants from Enova and capital raised through a private placement.