On the Nile Fan's wave power potential and controlling factors integrating spectral and geostatistical techniques

Abstract

Wave energy is foreseen to contribute largely to the renewable energy projected to supply 20% of Egypt's electricity budget to meet burgeoning energy demand. Therefore, this research analyses the Nile Fan wave energy forecasted from numerical modeling for 2020 of the Copernicus Marine Environment Monitoring Service (CMEMS) database, hourly spatially sampled at 0.042° as the finest scale remotely-sensed data available. Wave energy spatial distribution is analyzed using data from 259 points proposed as Wave Energy Converters (WECs). Spectral analyses techniques were appraised for disclosing the frequency and energy return periods of the significant wave height and peak periods and to understand the similarity among selected WECs of varied conditions. Factor analysis is conducted to investigate the magnitude of factors controlling the wave dynamic and energy potential. K-means clustering was used to distinguish energy classes with large inter-class variances. The obtained resources (average wave energy density, around 5.32 KWh/m; maximum recorded value of 112.9 KWh/m; annual wave energy density sum of about 46.96 MWh/m) are among the largest found in the Mediterranean Sea. Spectral analysis clarified a strong periodicity at 21 days, intermittent periods of 2.66 days, and 7.5 days dominate over the year while a 22.6 hourly period dominates in summer. January attained the strongest peak frequency of 8.4 in the west, 6.6 between the NW and SE sites, 5.20 for the near shore sites. Directional analysis indicated a bimodal wave system (325° and 285°-295°) in the west and unimodal (285°295°) in the east, while the central area showed combined distribution; bimodal in the deep water and unimodal near the shore. The 285°-295° wave direction showed largest contribution to the wave energy density. The northwest is the most energetic and most productive area. Monthly and seasonal wave energy clarified maximum of 9.98 MWh/m in January and 22.6 MWh/m in winter that contributes to 21% and 53% of the yearly mean, respectively. The wave energy resource is more than 3.5 times greater in winter than in summer. Exploitable energy density level exceeding 2 KWh/m are recorded for 250 sites out of the 259 site. Factor and detrended correspondence analyses confirmed that more than 98% of the Nile Fan's wave energy variance is controlled, in decreasing order of influence, by the depth, distance to shore, significant wave height, wave peak period, and wave principal direction. Four classes of varied statistics and hence different wave behavior were distinguished affected by the depth, morphology of the shoreline, and the dominating wave direction. Deepest water and near shore classes attained the largest wave energy. Further details on the effect of the environmental factors on the wave shape and corresponding energy are concluded.