The sea currents around Malta : a preliminary study for harnessing underwater ocean current energy

Abstract

This study investigates the possibility of producing electricity from deep ocean currents flowing by the Maltese Islands like the Atlantic Ionian Stream and the Levantine Intermediate Waters. The main goal is to identify potential locations at potential depths to host hydrokinetic turbines and convert seawater motion into electrical power. The used data for this purpose is a hydrodynamical numerical model developed by the Copernicus Marine Service entitled “The Mediterranean Sea Physics Forecast and Analyses”. On a daily basis with approximately 4km spatial resolution and 141 layers within the water column, this model provides information about velocity profiles and flow direction. By averaging in time over the whole year of study (2022) two potential hotspots were identified as they have the highest annual mean seawater velocity. One is located in the Malta – Sicily channel inside Italy’s territorial waters and the other is located by Malta’s southern coasts. The comparison between the different depths at these two locations separately, led to identify the first 50m as potential depths to install turbines in the northern hotspot while the depth for the southern hotspot was at about 276m below the surface. This comparison was based on the 2022 annual average plots that were created to investigate seawater velocity variation with depth while smoothing out the temporal variability. The timeseries analysis of these two locations at these specific depths indicated that the underwater currents targeted are respectively the Atlantic Ionian Stream in the north and the Levantine Intermediate Water in the south. Besides, it helped in studying the seasonal variation and dynamics of these currents and lead to the identification of the maximum and minimum calculated velocities. The Kairyu turbine developed in Japan to harness offshore currents energy was found to be most suitable in this study. By adopting this technology, considering the Copernicus model output and adopting some hypothesis, a quantification of the produced energy has been done. According this research, Malta can be able to provide the national annual demand for electricity in some conditions. However, further studies must be conducted to investigate the feasibility of such project on the economical, juridical, and technical levels.