Experiments with point absorbers for wave energy conversion

Although many existing and proposed wave energy devices operate as point absorbers, for which the overall efficiency depends upon the frequency and magnitude of the buoy's displacement, there is little experimental data presently available with which to optimise power outputs. A harmonic model is presented for the resonant frequency and absorption efficiency of bodies that oscillate in heave mode. The model is tested with a series of still water experiments and with monochromatic wave experiments in a laboratory flume incorporating an axi-asymmetric buoy. The results support the theoretical analysis. Empirical relationships are derived for the added mass and damping of the system. The laboratory experiments demonstrate an empirical absorption efficiency in excess of 80% at resonance