The Fri-El seapower system consists of a vessel or pontoon, moored to seabed, to which several lines of horizontal axis hydro turbines are attached. The same pipes, connecting the turbines through cardanic joints providing the necessary flexibility to the system, transfer the power captured from the water on board of the pontoon. Pipes are here connected to electrical permanent magnet generators (PMG) that are kept out of the water in order to simplify and diminish their maintenance. The electric generators transform the power carried by the transmission lines into electrical energy, which can be directly fed into the grid through an undersea cable, connecting the individual floating structures to a submarine hub, which in turn is connected to the shore by a single submarine cable. Alternatively, the systems can be installed offshore far away from the coasts and hydrogen can be produced with the electricity generated by the turbines.
Strait of Messina, Sicilian Coast, Italy
Permitting process of the final system (Messina III) has been initiated.
After several numerical simulations, a first validation of the studies has been made by testing a prototype of the system in the water towing tank of the Naval Engineering Department of the University of Naples “Federico II”. Soon after the controlled tests, a series of open water prototypes tests have been carried out in the Strait of Messina in order to check the system well working in real conditions.
In July 2008, a reduced scale of Sea Power prototype (10 turbines; 6 kW - 2.5 m/s; Messina I) was launched and in 2009 later another bigger prototype (6 turbines; 20 kW - 2.5 m/s) was tested in the same waters (Messina II). Although the final system (Messina III) started to be designed and conceived to produce up to 500 kW with a nominal flow speed of 2.5 m/s in the Strait of Messina the project did not have further development.
Key Environmental Issues
Conceptual model for evaluation of environmental impacts in the Strait of Messina (source: El-Geziry et al., 2009). These are key environmental issues suggested to take into account regarding the development of tidal projects to be installed at the Messina strait.
The main sources of the observed environmental impacts may be classified in four categories:
1. Kinetic energy removal
2. Rotor and support structure
3. Noise levels
4. Installation/decommissioning disturbance.
These sources have direct/indirect impacts on the following components of the marine environment:
1. Tidal current velocity
2. Tidal current dynamics
4. Sedimentation and seabed
5. Turbidity and water quality
6. Marine ecology.