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Investor Presentaiton

Energies 2019, 12, 3658 26 of 37 The PTO system is located on the topside deck and consists of a gearbox and a rotational generator (Figure 21). The vertical motion of the buoy is transferred through a central rod (heave stem) to the gearbox. Then, the pulley converts the vertical movement into rotation that is adequate for the electrical generator. A backstop system unifies the rotation direction using freewheels. This implies that the buoy can drive the PTO system either upwards or downwards. A solid cylindrical flywheel is used to amplify the rotational inertia as well as smooth the delivered energy to the generator. Additionally, the PTO system includes a gearbox that multiplies the rotational speed so that it is adequate for power generation. == The location that has been considered for installation of the WEC is near to a small island called "Ilha Rasa". The location's water depth is about 20 m, and its distance from shore (Copacabana beach, Rio de Janeiro, Brazil) is about 14 km. The predominant wave climate of the region is a peak period of Tp = 9.6 s and a significant height of Hs 1.33 m. Shadman et al. [189] showed that a very large buoy is required to maximize the power absorption in a region like nearshore Rio de Janeiro, where the predominate wave periods are beyond 7 s. This might lead to higher costs, which could make the project economically infeasible. Hence, a specific control called "latching", presented originally by Budal and Falnes [190], was applied on the WEC to overcome this challenge. Latching is a mechanical control method that tunes the natural period of the buoy to the predominate wave period of the sea site by halting and releasing the buoy at its motion extremum. As a result, larger buoy motion amplitude and velocities can be achieved, leading to higher power production. Eventually, the latching control enables a smaller buoy with a smaller natural period to be tuned with such a wave climate [191]. A hydraulic system is designed and tested for latching the oscillating buoy. Backstop Speed Multiplier Flywheel Generator Pulley Buoy Stem Figure 21. Schematic view of the power take-off (PTO) system. Experimental tests of small-scale models, shown in Figure 22, were performed in a wave and current channel (LOC) at the COPPE/UFRJ. The hydrodynamic behavior of the buoy was studied by applying different modeling scales including 1:17, 1:20, 1:30, and 1:40. Additionally, a strategy was developed to investigate the effect of latching control on the WEC. (a) (b) Figure 22. Experimental tests of the COPPE nearshore WEC in a wave channel: (a) 1:17 scaled model, (b) instruments for data acquisition.
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