Digby County, Nova Scotia: Nautricity Ltd. and Fundy Tidal Inc. announce the signing June 24 of an MOU to develop a 500kW tidal project in Nova Scotia’s Petit Passage.
Nautricity is completing system testing of its CoRMaT and Hydro-buoy technologies at the European Marine Energy Centre (EMEC) off the Orkney Islands in Scotland. The project at Petit Passage provides flows similar to those at the EMEC site and approach the speeds found at the FORCE (Fundy Ocean Research Centre for Energy) site in Nova Scotia.
Nautricity explains that its CoRMaT second generation tidal turbine employs two closely spaced contra-rotating rotors, driving a contra-rotating electrical generator. The first rotor has three blades rotating in a clockwise direction while the second rotor, located directly behind the first, has four blades rotating in an anti-clockwise direction. This doubles the relative rotational speed compared with a single rotor turbine, allowing the turbine to directly drive a flooded, permanent magnet, contra-rotating generator, without a gearbox. The flooded generator is cooled passively by the water, eliminating parasitic energy losses associated with gearbox-driven water-tight active oil based gearbox-generator cooling systems and power absorbing shaft seals.
The magnetic field acts across the rotor and rotating-stator sections of the generator as a “differential”, equally splitting the torque between the two rotors. Reactive torque acting on the supporting structure is eliminated, allowing the system to be moored rather than rigidly attached to the seabed. This enables the turbine to be deployed in water depths from 8m – 500m.
Tidal flow induced drag forces ensure that the turbine remains perpendicular to the flow at all states of the tidal diamond, resulting in maximum energy capture.
Expected deployment of the turbine in Nova Scotia will be in late summer of 2015. The MOU not only facilitates the delivery of this important project, but also provides for collaboration on a wide range of issues, from grid connection and storage to participating in research and development initiatives at both Scottish and Nova Scotia universities.
Nautricity, a University of Strathclyde spin-off company, is a tidal energy technology developer based in Glasgow, Scotland developing next generation tidal energy solutions.
They have recently received full consent for their tidal site at the Mull of Kintyre in southwest Scotland. Fundy Tidal is a community based tidal developer in Nova Scotia that has approval for 3MW of tidal COMFIT projects in Digby County.
In a second project in the Bay of Fundy, German marine propulsion manufacturer Schottel has announced details of a 2.5 MW ocean power demonstration berth that its subsidiary Black Rock Tidal Power, Inc. plans to install there. The device, a platform named Triton and developed by TidalStream Ltd., using inexpensive small and robust tidal turbines, is semi-submerged, floating and freely aligns to the ocean flow.
The company explains that most of the existing tidal current energy systems that have been deployed to date are single turbines designed to rest on the seabed. The single turbine approach leads to enormous machines. Besides the high capital expenses for these huge machines, the operating expenses are significantly driven by the necessity to transport the devices to a maintenance base, requiring heavy gear, expensive vessels and suitable onshore infrastructure.
Using the Triton platform, the electrical power produced by the individual turbines is collected and conditioned in the electrical room located inside the platform system. The power electrics and control systems are easily accessible for maintenance. Grid compliant electric energy is transferred by cable from the floating structure. Additional conditioning of the electrical energy on shore is not required. A gravity base foundation is used to anchor the platform system and lowered down to the seabed prior to the final installation. The whole structure is assembled at shore and then towed out to the installation location.
The two projects will be showcased at the Fundy Ocean Research Center for Energy (FORCE), Canada’s research centre for in-stream tidal energy, located in the Bay of Fundy.