Analysis of the wave energy in an archipelago

WAVEWATCH III model is implemented in the entire North Atlantic Basin, providing the boundary conditions for the implementation of the SWAN model, on the Canary Islands domain. The results of the model are compared with measured data from Gran-Canaria buoy, over a period of 10 years between 2001 and 2010, showing a generally good agreement. Wave energy distribution is evaluated and the results show an average annual energy availability of 20kW/m. It is verified that the East coast of the islands presents little variability and that the North/Northwest coast of the islands exhibits greater energy availability. The results show that in the most energetic areas the seasonal average varies between 15-20 kW/m, in the spring and 25-30 kW/m, in winter, while in the less energetic areas the seasonal average varies between 10-15 kW/m, during spring, and 15-20kW/m, in winter. The results allow us to conclude that the North/Northwest coasts of La Palma, El Hierro and Fuerteventura, as well as the north coast of La Palma, Tenerife and Lanzarote, have highest energy availability, while in the other islands (Gran-Canaria and La Gomera) this availability is clearly lower. proach is adopted for the assessment of wave energy along the Portuguese coast (Rusu and Guedes Soares, 2009), as well as for the Azores (Rusu et al, 2012) and Madeira (Rusu et al, 2012). Also for the Cape Verde Islands, Bernardino et al. (2017) studied the energy profile, showing an average potential above 7kW/m and identifying areas with considerable energy to the exploration of wave energy. Also visible is the shadow effect produced by the islands located to the west (Barlavento islands), attenuating the wave energy in the coast of Sotavento islands. In other studies, the WAVEWATCH III model was used for the North Atlantic Basin, providing the boundary conditions for the SWAN model in the different study areas. This methodology was implemented for the southwest of the United Kingdom (Bento et al, 2011a); the west coast of Ireland (Bento et al, 2011b); northern Spain (Bento et al, 2012); Portugal (Silva et al, 2012); the west coast of France (Gonçalves et al, 2014a) and the Canary Islands (Gonçalves et al, 2014b). The results showed good consistency between observations and measurements in these areas. Following these studies, in Guedes Soares et al., (2014a and 2014b), the validation of the hindcast system implemented for the different areas, is presented. Other studies concerning the energy potential in the Canary Islands have been carried out. The areas of greatest potential are located mainly on the north coast of the islands. The studies by Iglesias and Carballo, (2010, 2011) and Sierra et al. (2013), show the geographic distribution of wave energy with an average power of 25kW/m. In the installation of wave parks, the choice of their location for optimum equipment performance is important and presupposes a prior study of the conditions of marine agitation, as well as the evaluation of the available energy in a given area. The energy recovery devices can be categorized according to their area of action: coastal, nearshore or offshore. Despite the greater risk and consequently higher cost, the general opinion is that the offshore installation of wave energy farms is the most appropriate. It is estimated that this exploration has a significant growth in the next decades due to the technological advance (Falcão, 2010 and Guedes Soares, et al., 2012). Although the main focus of this study is the evaluation of the energy potential in the Canary Islands, a study on the performance of some energy converters in the area was also carried out. When selecting a wave power converter, factors such as: easy access to the device at any time, energy storage capacity, among others, should be taken into account, as for example in Cortadellas et al., (2011), Carballo and Iglesias, (2012), Guedes Soares et al., (2012), Silva et al. (2013), Andrés et al., (2014), Rusu et al., (2014). For this study 8 points along the islands were considered and the available energy is evaluated at these points. Then, 6 wave energy converters were considered: Wave Dragon, Wavebob, Pelamis, Oceantec, Aqua Buoy, Seabased AB, and their performance are evaluated, for each of the selected points. The study here presented is a reconstitution of the wave energy potential for the Canary Islands, implemented for a period of 10 years, between 2001 and 2010. 2. DESCRIPTION OF THE WAVE HINDCAST SYSTEM 2.1. Theoretical Formulations Two state-of-the-art spectral wave models are used to characterize the transformation of wave climate from offshore to the nearshore. Both SWAN and WAVEWATCH III (WWIII) solve the spectral energy balance equation that describes the evolution of the wave spectrum in time, geographical and spectral spaces given by: