From standalone to interconnected: Sector-coupled optimisation of La Gomera’s renewable energy portfolio for integrated energy planning

Small islands offer unique opportunities to test and implement energy system decarbonisation strategies. Their isolation provides a controlled setting to analyse renewable integration, sector coupling, and grid flexibility, while their reliance on imported fossil fuels highlights the urgency of transition. La Gomera, an island in the Canary Archipelago (Spain), represents a strategic case study given its ongoing shift away from conventional fuels and its planned interconnection with Tenerife. This study develops a replicable framework for small island decarbonisation planning, combining EnergyPLAN simulations with a MATLAB-based optimisation routine. A stepwise modelling strategy was applied, progressively expanding the system from a stand-alone configuration to increasingly complex scenarios. Initial optimisation focused on photovoltaic and wind capacities, followed by the introduction of: (i) a subsea cable to Tenerife; (ii) a waste-to energy facility; (iii) battery energy storage; and (iv) transport electrification at varying penetration levels. Each phase was re-optimised to reflect updated system conditions. A simplified representation of Tenerife’s electricity demand was integrated to assess interconnection performance and explore the role of offshore floating wind power generation. The results demonstrate that, even under conservative assumptions, optimised renewable portfolios for La Gomera are economically competitive and enable significant emission reductions. Interconnection and cross-sectoral coordination emerged as key enablers of system flexibility and renewable utilisation. While the analysed scenarios are subject to spatial and regulatory constraints, they provide a robust foundation for long-term planning. The methodology proposed here is transferable to other insular regions, offering a pathway towards resilient, integrated, and decarbonised energy systems.