Design and Optimization of a Multi-Layer (Battery + Hydrogen) Energy Storage-Based Hybrid Microgrid for Gökçeada Island

Ensuring reliable energy supply in islanded and off-grid communities has become a significant research challenge due to the intermittent nature of renewable energy sources and the environmental impacts associated with fossil fuel dependency. Although hybrid energy systems based on solar and wind resources offer sustainable solutions for such regions, the literature widely reports that system performance is strongly dependent on the adopted energy storage architecture. In particular, battery-only energy storage systems, while effective for short-term power balancing, are often insufficient to address long-term and seasonal energy deficits in isolated microgrids. Recent studies highlight that enhancing system flexibility through the coordinated use of multiple energy storage technologies is a key factor in achieving high renewable energy penetration. In this context, battery energy storage systems are well suited for fast response and short-term energy management, whereas hydrogen-based energy storage systems, due to their high energy density and long-duration storage capability, are increasingly considered a promising solution for managing prolonged and seasonal energy imbalances. Multi-layer energy storage approaches aim to combine the advantages of these technologies to improve the technical and economic performance of hybrid microgrids. In this study, a fully renewable hybrid microgrid with a multi-layer energy storage architecture is designed and optimized for a real island location, Gökçeada, Türkiye. The proposed system integrates solar photovoltaic and wind energy generation units with a lithium-ion battery for short-term energy balancing and a hydrogen-based energy storage subsystem consisting of an electrolyzer, hydrogen storage tank, and fuel cell for long-term energy management. This configuration aims to reduce battery cycling stress while enhancing overall energy supply reliability. The system is modeled and optimized using the HOMER Pro software based on hourly energy balance calculations, real meteorological data, and an island-specific load profile. A comparative assessment is conducted between the proposed multi-layer energy storage system and conventional hybrid systems employing battery-only storage. Key performance indicators, including net present cost, cost of energy, renewable energy penetration, supply reliability, and excess energy generation, are evaluated. The results demonstrate that the coordinated operation of battery and hydrogen energy storage systems significantly improves system flexibility, extends battery lifetime, and enhances long-term economic and environmental performance in islanded microgrids. This study provides a comprehensive and application-oriented contribution to the literature by demonstrating the feasibility and benefits of multi-layer energy storage architectures for renewable energy–based island microgrids.