The potential of extracting wave energy from rip currents
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Existing wave energy converters are only based on a few ways to produce electricity from ocean waves. All of them suffer from low cost-efficiency so the proposal of new technologies is still up to date. This is a preliminary study to an innovative concept, based on wave-induced currents. As waves propagate into shallow water and break over a barrier, they dissipate their energy. The latter can be partly transformed in a hydraulic potential through the wave set-up behind the barrier and the cross-shore mass transport from waves. Electricity can then be produced by the mean of a water turbine.This study estimates qualitatively this energy potential. The 2D set-up is analyzed by the model of Calabrese et al. (2008) and is adapted to 3D for a regulated net cross-shore discharge. The 3D model of Bellotti (2004) is also used. Experiments have been carried out on a simplified lab-scale model to check qualitatively the applicability of the models, determine experimentally their calibration parameters and find the optimal combination flow rate/pressure head which gives the highest hydraulic potential. Two different barrier profiles are tested: a breakwater-like barrier with a steep seaward slope and a sandbar-like barrier with a mild slope. Despite a significant uncertainty, experimental and analytical results correlate well.The conclusions on the future of this technology are not thorough. Experimental conditions applied to full scale show a quite low efficiency compared to the main competitors, but much more perspectives of optimization are conceivable. Some of them have been studied from an analytical point of view.