Inter- and intra-annual variability of wave energy in Northern mainland Portugal: Application to the HiWave-5 project

Abstract

Ocean wave energy capacity has been pointed out as one of the unexplored renewable energy sources to help reach net zero carbon emissions by 2050, contributing to meeting the European Green Deal targets. However, despite the broad range of wave energy converter technologies already developed in a sustainable and economic model, there is still a lack of structured projects with high performance beyond the prototype stage. This paper investigates the potential for large-scale electricity production by the innovative HiWave-5 project in Aguçadoura (on the Northern coast of mainland Portugal). Wind–wave data (1950–2020) from the ERA5 reanalysis model are used to estimate inter- and intra-annual wave energy variability in Aguçadoura. ERA5 data is compared with field wind–wave data recorded between 2012–2019 near the study area. A mean wave power resource of 25.84 kW/m is obtained, for a possible device capture equal to 119.45 kW, despite a considerable intra-annual variability (ranging between 8.03 and 47.57 kW/m) and inter-annual variability (between 18.29 and 35.47 kW/m). Results show that local wave conditions do not substantially compromise the absolute performance of the device, given its survival limitations to adverse conditions. Considering a Levelized Cost of Energy of around €60/MWh, an annual investment of €62 885 is estimated, tending to meet targets for large sustainable electricity generation with the exponential growth expected until 2030, aided by the increase of devices in an energy farm concept. Wave power resources estimated using ERA5 data can underestimate about 7.20% values obtained with the wave buoy data.