Beach response to wave energy converter farms acting as coastal defence

• New experimental results on transmission coefficients beyond WECs is presented.
• WEC farms performance for coastal defence are evaluated in two study sites.
• Wave fields induced by the WEC farms are evaluated with TMA spectrum.
• Beach response is evaluated using the continuity of sediment equation.
• All the WEC farms were found to cause beach accretion, at least in small areas.

One of the greatest challenges of coastal engineering today is the need for coastal protection in the changing climate scenario. Places which are nowadays protected will demand upgraded defences and more sites will require security; in all cases a large amount of resources will be needed to ensure beach maintenance and coastal safety. This may be an opportunity for the multi-purpose use of Wave Energy Converters (WECs) if the foreseen increase of energy demand in coastal areas is also considered. In this paper a group of WECs based on different operating concepts is numerically tested in front of two beaches, i.e. the Bay of Santander in Spain and Las Glorias beach in Mexico, representing two different case studies where the long-shore sediment transport is dominant. The hydrodynamics induced by these devices is represented by means of a 2D elliptic modified mild-slope model that is calibrated against new experimental results. The wave field is then used as input for the analytical calculation of the long-shore sediment transport and the coastline trend is estimated by applying the continuity of sediment equation. The characteristics of the selected numerical models give this work a first approach level. All the devices were found to produce a positive trend (accretion) at least in small areas. Recommendations are given to facilitate the selection of the device and the design of the farm layout for shore protection purpose.