Assessment of the Wave Energy Conversion Patterns in Various Coastal Environments

Abstract

An important next stage in exploiting the ocean energy potential is to install several identical devices within an array, like doing in wind farms, to raise in this way their overall electricity production. The way in which the ocean energy devices will perform, as well as their economic viability, is critically linked to their design and moreover they depend directly on the specific environmental conditions characteristic of a certain area. Thus, due to the specific wave climate, one device can perform better than another in a particular coastal area while in another nearshore area the situation might be completely reversed. From this perspective, the main objective of the present work is to assess the performances of various WEC devices that would operate in different coastal environments. Three different groups of coastal environments were considered. They are: (I) the Iberian continental nearshore covering both Spanish and Portuguese coasts, (II) the Canaries Islands and the Archipelago of Madeira and (III) two enclosed seas (Black and Caspian seas). Various wave energy converters were evaluated covering the full range of the existing devices. Among these, the most representational devices considered are: Wave Dragon, Pelamis, Archimedes Wave Swing, Aqua Boy, Oyster, Langlee and Wave Bob. In order to evaluate the electric power expected in a certain location, the bivariate distributions of occurrences corresponding to the sea states defined by the significant wave height and the energy period were designed in each coastal area. The wave data were provided by hindcast studies covering extended time periods that were performed with numerical wave models based on the spectrum concept. The transformation efficiency of the wave energy in electricity was evaluated via the load factor and also through an index defined as the ratio between the electric power estimated to be produced by each specific WEC and the expected wave power corresponding to the location considered.The present work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments. Moreover, the results can be easily extrapolated to some other nearshore areas.