Development, Analysis and Comparison of two Concepts for Wave Energy Conversion in the Mediterranean Sea

The investigations carried out during this Ph.D. programme relate to the marine engineering field, more specifically to wave energy conversion. Two different wave energy converters have been modelled numerically with the aim to assess the feasibility of wave energy conversion in the Mediterranean Sea. The first studied wave energy converter, named HPA-LG, is a heaving point absorber with a linear generator placed at the seabed. Two variants of the WEC have been examined, paying particular attention to the floater dimensions and to the geometrical design of the PTO. Initially, only the heave mode has been modelled and the performance of both devices has been analysed. Subsequently, the surge mode has been added to the model and its effect in prevalent heaving point absorbers has been studied. For the two-body device, although the dynamic behaviour changes when the surge is included, no relevant differences are observed regarding the power production. When studying the three-body device, results show two clear trends, for steep waves the surge leads to a decrease in the production, for flatter waves it affects positively the power absorption. However, the overall the negative contribution is more relevant. The MoonWEC is the second studied wave energy converter, it merges several working principles with the aim to benefit from the assets of each single principle. It consists in a hollow floating structure, where water fills a central whole creating a moonpool. Device optimization has also been carried out, six different CALM mooring configurations and three Wells turbines have been tested. Both device show similarities in their performance, their production is maximised for a specific range of wave conditions. The HPA-LG has a broader optimal range. However, the MoonWEC is more efficient for mild wave conditions, its annual energy production is [50-100] % higher, depending on the location and HPA-LG variant