As the quest for clean renewable energy intensifies the proposition of extracting energy from ocean waves sounds increasingly more attractive. The wave energy resource is recognized to contain the highest energy density among renewables and is virtually inexhaustible. Moreover unlike wind the wave climate is more predictable and is generally less intermittent. The primary waves of interest are those generated by the blowing of the winds which in turn are a product of differential heating of the earth. Therefore the wave energy may be considered as a concentrated form of solar energy. The size (and associated energy) of the resulting waves are a function of wind speed wind duration and distance over which the wind blows referred to as fetch. Original solar power levels of 100 W/m2 can be transformed into waves of power levels of over 1000 kW/m of wave crest length. Researchers at UC Berkeley have developed a new device that applies the principle of parametric excitation to ocean wave energy converters. The proposed mechanism operates fully autonomously when the buoy is heaving. The application leads to greater energy in the oscillatory motion resulting in increased motion amplitude or in situations where amplitude limit is reached the possibility of using higher damping values in the power takeoff system to keep the oscillations bounded. In either case when power take off is achieved with hydraulic damping it would be possible to harness significantly more power from the device compared to a unit simply excited by the waves. Applications: 1) Wave energy converters 2) Wave energy converter arrays
Greater energy in the oscillatory motion resulting in increased motion amplitude.