Dual-use wave energy converter arrays: Experimental insights into nearshore processes and coastal erosion

Wave energy converter arrays have the potential to serve a dual purpose: generating renewable energy while reducing wave energy in their lee and subsequently modifying nearshore processes including wave refraction, diffraction and nearshore currents, all of which influence sediment transport at the shoreline. Understanding the interactions of these physical processes to achieve this dual purpose is complex, and detailed observations to support the design of suitable wave energy converter arrays are lacking. This paper reports on an extensive wave basin experimental program that measured shoreline changes on a sloping, light weight sediment beach, as a function of the incoming irregular wave conditions and five different 16-device wave energy converter array configurations. A key finding is that reducing wave height alone is insufficient for coastal protection; it is also essential to account for wave radiation stresses and the resulting induced currents in the lee of a nearshore wave energy converter array. These currents can lead to zones of shoreline accretion and/or erosion, which are shown to be sensitive to both incident wave conditions and array configuration. Designing wave energy converter arrays for dual use therefore requires careful consideration of nearshore hydrodynamics, sediment transport processes, and site-specific wave conditions.