Design procedure of an innovative turbine with rotors rotating in opposite directions for the exploitation of the tidal currents

In this work an innovative on-shore marine turbine has been deployed. The peculiarity is the anchoring system, consisting in a rope subjected only to a tensile stress, a central deflector, responsible of the equilibrium in the horizontal plane, and a floating stabilizer, keeping the machine in vertical position. The introduction of a couple of rotors, instead of one, has been an important step in the machine design. By rotating in opposite direction the rotors make the machine free from any torsional effects. Based on the experience gained, the design procedure of this turbine is described. Considering the equilibrium conditions as a key point of the design, the equations in the horizontal and vertical plane are obtained. In the horizontal plane the equilibrium is guaranteed by a central deflector while in the vertical one is guaranteed by a buoyant stabilizer. After several calculations and simulations, carried out for the site of Punta Pezzo (Messina - Italy), the energy output and the payback time has been evaluated.