The Role of Green Hydrogen as Seasonal Storage Solution for Achieving 100% Renewable Energy Systems by 2040: The case of São Vicente, Cape Verde

Abstract

Small Island Developing States (SIDS) such asS˜ao Vicente Island in Cabo Verde face compounded energy challenges due to their reliance on imported fossil fuels, grid isolation, and vulnerability to climate impacts. While renewable energy offer saviable path forward, the inherent variability of solar and wind resources on S˜ao Vicente, particularly these seasonal fluctuations in their availability, necessitates effective long-term storage solutions to ensure grid reliability and a consistent power supply. This study assesses green hydrogen as a seasonal energy storage option and benchmarks it a gainst battery-only and no-storage configurations, and how it could support S˜ao Vicente in reaching a 100% renewable energy system by 2040, representing the first green hydrogen storage assessment for a West African SIDS. A multi-scenario modelling approach was applied using the COMANDO(Component-Oriented Modelling and Optimization for Non linear Design and Operation) energy systems modelling tool, exploring four distinct 2040 system configurations: (i) PV and wind without storage, (ii) PV and wind with battery storage, (iii) Pv and wind with hydrogen storage, and (iv) PV and wind with a hybrid battery-hydrogen storage. The systems were evaluated based on key technical and economic performance indicators including Levelized Cost of Electricity (LCOE), Loss of Power Supply Probability (LPSP), and Total Annualized System Cost (TAC). A cost-sensitivity analysis is also performed to understand how system costs respond to changes in component cost developments. Additionally, a qualitative assessment was conducted on limiting and enabling technical, economic or policy factors that could influence the long-term viability, providing a broader view of circular-economy benefits and implementation barriers. Results show that the hybrid storage system (Scenario-iv) achieved the most balanced outcome, meeting the technical criteria of 0% LPSP and 100% renewables hare while maintaining a competitive LCOE of 0.0503 C/kWh and a TAC of 6.97million C/year. Compared to single-storage configurations, the hybrid configuration reduces system costs by 25% and virtually eliminates unmet demand. Sensitivity analysis revealed that system cost is most affected by variations in wind turbine costs and, within storage technologies, electrolyser costs. A qualitative assessment of long-term viability factors highlighted that, technical challenges such as seasonal variability and low grid inertia must be addressed through advanced solutions like grid forming inverters and Virtual Synchronous Generators (VSGs). Economic barriers include high upfront investment and financing constraints, while enabling factors include Cabo Verde’s strong political commitment, abundant renewable resources, and supportive policy direction.