Abstract
The main objective of the present work was to assess and compare the wave power resources in various offshore and nearshore areas. From this perspective, three different groups of coastal environments were considered: the western Iberian nearshore, islands and an enclosed environment with sea waves, respectively. Some of the most representative existent wave converters were evaluated in the analysis and a second objective was to compare their performances at the considered locations, and in this way to determine which is better suited for potential commercial exploitation. In order to estimate the electric power production expected in a certain location, the bivariate distributions of the occurrences corresponding to the sea states, defined by the significant wave height and the energy period, were constructed in each coastal area. The wave data were provided by hindcast studies performed with numerical wave models or based on measurements. The transformation efficiency of the wave energy into electricity is evaluated via the load factor and also through the capture width, defined as the ratio between the electric power estimated to be produced by each specific wave energy converters (WEC) and the expected wave power corresponding to the location considered. Finally, by evaluating these two different indicators, comparisons of the performances of three WEC types (Aqua Buoy, Pelamis and Wave Dragon) in the three different groups of coastal environments considered have been also carried out. The work provides valuable information related to the effectiveness of various technologies for the wave energy extraction that would operate in different coastal environments.
Highlights
In the medium to long term, wave energy has been identified as having the potential to make a significant contribution to the European and global energy system
The extents of the geographical spaces corresponding to the subsequent northern and central computational domains are illustrated. (b) and (c) the northern and central domains defined in the Portuguese nearshore, SWAN simulations corresponding to the time frame 2010/04/22/h18 reflecting average wave energy conditions, the positions of 15 reference points are defined in each case (NP and CP-points, respectively)
For Wave Dragon the average values of the capture width are between 22.28 and 73.05, for Pelamis between 1.61 and 4.2, while for Aqua Buoy the range is (0.78–1.5). Another observation, coming from the analysis of the results presented in Table 10, would be that the values of this index are lower for WT in comparison with total time (TT), which means that, in winter time the wave energy is higher, the efficiency of its transformation into electricity is lower
Summary
In the medium to long term, wave energy has been identified as having the potential to make a significant contribution to the European and global energy system. The technologies are still in early stages of development, but the evolution of the wave energy converters is very dynamic and major technology improvements are expected in order to make the wave energy economically viable. The trend of increasing the renewable energy extraction is highly motivated by the global awareness related to the need for a transition to a lower-carbon energy system, since greenhouse gas emissions are recognized factors in the climate changes. The decarbonization of the energy sector due to low carbon technological innovation is fundamental in achieving emissions reduction targets. Renewable energy technologies face opportunities and challenges as a result of this desire for “accelerated innovation” [2,3]
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