Multi-carrier based optimization of renewable energy communities in small non-interconnected islands

Small islands encounter major obstacles in the path toward energy sustainability, mainly due to their dependence on isolated grids and imported fossil fuels. The intermittency of solar and wave energy systems can be mitigated relying on Renewable Energy Communities, whose main aim is to share the renewable energy produced among community members. Although Renewable Energy Communities are mainly based on electricity sharing, further advantages might be attained by introducing a multi-energy approach, exploiting also thermal, freshwater, and hydrogen final consumption. This study proposes a method for the integration of a Renewable Energy Community on small islands based on multi-energy systems analysis and optimization. As applicative case study, the methodology is here applied to Favignana, a small island in the Mediterranean Sea. The research analyzes step by step various scenarios aimed at increasing the share of renewables, particularly solar and wave energy. All the scenarios were evaluated exploiting a multi-objective mixed-integer linear programming algorithm coordinating many equipments to minimize annual costs, annual primary energy use and annual carbon emissions. The analysis shows that renewable energy penetration increases from 13-18% in the baseline up to 75% with the integration of electrical storage and hydrogen-based technologies. Consequently, a huge reduction of fossil fuels can be obtained through an advanced Renewable Energy Community and the integration of hydrogen use for mobility. Smart management of desalination plants for freshwater production can be fully integrated to enhance the energy sharing and the decarbonization of these energy systems.