This study examines whether green hydrogen production using combined wind and solar energy on Marmara Island can meet the island’s electricity demand and fuel the fuel needs of a hydrogen-powered ferry. A hybrid system consisting of a 10 MW wind farm, a 3 MW solar PV system, and a PEM electrolyzer sized to meet the island’s hydrogen demand was modeled for the island, located in the southwestern Sea of Marmara. The hydrogen production potential, energy flows, and techno-economic performance were evaluated using HOMER-Pro 3.18.4 version. According to the simulation results, the hybrid system generates approximately 62.6 GWh of electricity annually, achieving an 82.8% renewable energy share. A significant portion of the produced energy is transferred to the electrolyzer, producing approximately 729 tons of green hydrogen annually. The economic analysis demonstrates that the system is financially viable, with a net present cost of USD 61.53 million and a levelized energy cost of USD 0.175/kWh. Additionally, the design has the potential to reduce approximately 2637 tons of CO₂ emissions over a 25-year period. The results demonstrate that integrating renewable energy sources with hydrogen production can provide a cost-effective and low-carbon solution for isolated communities such as islands, strengthening energy independence and supporting sustainable transportation options. It has been demonstrated that hydrogen produced by PEM electrolyzers powered by excess energy from the hybrid system could provide a reliable fuel source for hydrogen-fueled ferries operating between Marmara Island and the mainland. Overall, the findings indicate that pairing renewable energy generation with hydrogen production offers a realistic pathway for islands seeking cleaner transportation options and greater energy independence.

The integration of green hydrogen into floating energy islands (FEIs) offers a transformative solution for sustainable offshore energy systems. This review explores the synergy between offshore wind energy and green hydrogen production, addressing critical challenges in renewable energy integration, storage, and decarbonisation. Key advantages of FEIs include enhanced grid stability, the ability to decarbonise hard-to-electrify sectors like shipping and heavy industry, and economic growth through job creation and hydrogen exports. These islands typically incorporate wind farms, electrolysers, diverse hydrogen storage solutions (compressed, liquefied, or chemical), and smart energy management, with innovations such as AI-driven optimisation and hybrid renewable systems (wave, solar, wind) improving efficiency. Some studies show that levelized hydrogen costs are as low as 2.4 €/kg and competitive with fossil-based alternatives. Case studies in the North Sea and Mediterranean demonstrate feasibility, supported by scalable modular designs. However, high initial costs, technical barriers in electrolysis, and regulatory hurdles persist. Overcoming these necessitates collaborative policy frameworks, R&D investments, and public-private partnerships. FEIs align with global climate goals, positioning nations at the forefront of the hydrogen economy and holding significant potential to accelerate the energy transition towards a resilient, low-carbon future.