Conversion of Wave Energy
The chapter starts from a review of wave energy converters from the 1960s to the present day. It points out that the recent U-oscillating water column (OWC) is better than the well-known OWC because of a greater eigenperiod, and because of the possibility of exploiting the experience with caisson breakwaters. However, passing from an OWC to a U-OWC calls for a radical change of calculation, which is dealt with in the chapter. Indeed it is no longer possible to exploit the Stoker solution (1957) for the waves generated by an oscillating pressure applied uniformly over a segment of the water surface. A crucial item of the new solution for the U-OWCs concerns the propagation speed cR of the reflected wave energy. The chapter shows that, with some swell, cR may be smaller than the group velocity with the consequence of both super-wave-amplification and superabsorption. Some evidence of this phenomenon is provided from a small-scale field experiment.