Abstract
The need of slowing down the global temperature increase due to climate change, has resulted in the search of new strategies to capture energy with low greenhouse gas emissions. In this line, ocean energy can both contribute to the reduction of greenhouse gas emissions and foster economic growth in coastal areas (Magagna and Uihlein, 2015).
While the technological development of devices is growing fast, their effects on coastal environments are not well-known and therefore these must be thoroughly investigated prior to WEC implementation. For that, new and modified versions of wave propagation models that allow the incorporation of device-specific WEC characteristics to specify obstacle transmission were developed and tested recently (Chang et al., 2016; McNatt et al., 2020; Millar et al., 2007). Several studies were carried out to assess WEC farms driven nearshore hydrodynamic impacts. Previous studies show that while the reduction of the significant wave height in the lee of the WEC farm can be relevant (up to 30%) it might be considerably variable depending on the WEC technology, distance from the WEC farm to the coast, initial wave conditions, and the configurations of WEC farm (Atan et al., 2019; Carballo and Iglesias, 2013; Chang et al., 2016; Contardo et al., 2018; Rusu and Soares, 2013). On the other hand, some relevant conclusions were drawn so far regarding the impact of WEC farm on beaches. For example, the discovery of the added benefit of the WEC farm by the possible substantial reduction in the beach erosion (Abanades et al., 2015; J Abanades et al., 2014a, 2014b; Bergillos et al., 2019a; Mendoza et al., 2014; Millar et al., 2007; Zanopol et al., 2014; Zanuttigh and Angelelli, 2013), coastal flooding (Bergillos et al., 2019a) and sea level rise driven shoreline erosion mitigation (Bergillos et al., 2019b).
An important aspect of WECs is the energy absorption dependency on wave frequency (for some devices also in wave amplitude), which varies according to their design. This dependency is expressed in terms of the Relative Capture Width curve (RCW) where the effective energy conversion is discretized in wave frequency, or the Power Matrix where the discretization is done both in frequency and amplitude.
Here, two case studies related to the impact of WECs on coastal morphodynamics are presented. The first case has the objective of investigating the long-term impacts of a WEC farm composed by a series of point absorber OWC (Oscillating Water Column) devices on nearshore wave climate and the consequences on the shoreline response; and the second case is focused on evaluating the changes in the wave spectrum caused by the frequency dependent’ energy absorption of bottom mounted energy converters and their impacts in the short-term morphological evolution.