For several years now, the Italian policy for the energy transition has included the progressive coverage of the energy needs of smaller islands not interconnected to the national electricity grid through local renewable sources. The studies conducted by RSE on smaller Italian islands highlighted the importance of integrated planning and management of the island water-energy system, where drinking water is supplied by desalination. To identify the most appropriate planning choices, we need advanced modeling tools to simulate the dynamics of the system in detail and to select the most efficient options with respect to multiple sustainability objectives.

This report describes the prototype of the O²WEnS model, a flexible tool to optimize the planning and management of the water-energy system of a generic off-grid island case study.

O²WEnS consists of a simulator combined with an optimization algorithm. The simulator can represent different electricity generation and storage technologies, as well as simulate the dynamics of a water system composed of a desalination plant linked to different drinking water storage tanks.

The optimizer enters the decision space by means of a recursive system simulation (simulation-based optimization), to identify the most efficient planning (capacity of renewable energy sources and storage systems) and management (operation of the desalination plant) solutions with respect to multiple sustainability objectives.

The O²WEnS model can be applied to any island system and is a valuable tool to support policy decision-makers and local operators in identifying the best intervention strategies to outline the decarbonization process of smaller Italian islands.