Estimation and analysis of offshore renewable energy potential for Mediterranean Sea.

In order to satisfy the need to increase renewable sources, in the future it will be necessary to focus also on the offshore ones. To date, this term refers substantially to offshore wind, in its two forms bottom-fixed and floating wind turbines, and ocean energy, which has among its resources wave energy as the most promising. Without their use it would be impossible to achieve the reliability and flexibility that renewable sources need.Given their importance, in this study a methodology has been designed to analyse data of wind and waves in the Mediterranean Sea, in order to obtain an estimate and evaluation of its potential.The study used eleven years of hourly weather data downloaded from the ERA5 site, from 2010 to 2020, while the writing is done using the MATLAB platform.The first part of the methodology uses wind (speed and direction) and wave data (period, significant height, direction) to create maps of resources power density and technology potential.These data are interpolated, using the MATLAB function interp2, to increase the accuracy of the grid ( it is possible to choose it), then the following constraints are set: bathymetry, protected areas, exclusive economic zones, distance from the coast and technological restrictions. These limits depend on the type of technology and are the main factors that influence the results of the analysis.The second part of the study, instead, carries out a metocean time series analysis of a precise location, always inside of the Mediterranean Sea, obtaining therefore the average values and the fluctuations of the resources and the technologies. In this case it is possible to choose the location of the study, but there is no possibility to interpolate the data as a time analysis is carried out. In this part is also added an evaluation of the extreme cases of the location.The results show that the technology with the highest potential is floating wind, with a value of about 18,500 TWh/year and a capacity of 3,290 GW. Values totally different from the bottom-fixed wind turbine that has about 2,410 TWh/year of energy potential and 224 GW for the capacity. This huge difference is mainly due to the difference in area available for the two technologies, because the Mediterranean seabed is very deep and it is impossible to install a bottom-fixed turbine over a maximum of 50-60 m.Wave energy has similar potential to the latter, but still higher, in fact it is about 4,670 TWh/year and 533 GW. Main limit for this source is the technological one, because the Mediterranean does not have a particularly high power density.These results highlight how in the Mediterranean it is necessary to focus on floating wind, although there is also the possibility to install some bottom -fixed wind turbine.  While, regarding wave energy, there is need to continue with the research to design new devices, as however, although there is a considerable potential, with the modern technologies it is not exploitable.