The majority of the Greek islands have autonomous energy stations, which use fossil fuels to produce electricity in order to meet electricity demand. Also, the water in the network is not fit for consumption. In this paper, the potential development of a hybrid renewable energy system is examined to address the issue of generating drinking water (desalination) and electricity while releasing zero pollutants into the atmosphere. Wind turbines supply wind energy, while an additional amount of energy is stored using pumped-storage hydropower and green hydrogen tanks. These two storage options are investigated for the purpose of storing and distributing clean wind energy in a controlled manner. Three scenarios are investigated. The first scenario only relies on the pumped-storage hydroelectricity technology (88% of the total annual power demand is covered), the second scenario investigates hydrogen storage technology (83% of the total annual electricity demand is covered), and the third scenario uses a hybrid storage solution consisting of pumped-storage hydropower and green hydrogen tanks (95% coverage).

The study aims to address the challenges of water scarcity and energy instability faced by small Mediterranean islands, exacerbated by tourism and population fluctuations. A Hybrid Renewable Energy System (HRES) is proposed to provide sustainable solutions by integrating wind turbines, pumped hydro storage, hydrogen storage, and desalination. The methodology involves simulating the system’s operation in two islands using historical data, wind energy calculations, and energy storage dimensioning. Three scenarios are evaluated: pumped hydro storage, hydrogen storage, and a combination of both, with a focus on covering water and energy demand, while minimizing costs. Results indicate that the combined storage scenario achieves 87% electrical demand satisfaction, surpassing single storage scenarios. Desalination ensures 99.99% water demand coverage across all scenarios, with marginal costs for potable water and energy calculated at 3 €/m³ and 0.016–0.131 €/kWh, respectively. The pumped hydro storage method proves more efficient, while hydrogen storage adds flexibility to the system. The findings highlight the adaptability of the proposed HRES for small islands globally, offering a replicable model for addressing the water-energy nexus. The study provides practical insights into integrating renewable energy, innovative storage solutions, and desalination for sustainable development in isolated regions.

This study explores the challenge of achieving water and energy self-sufficiency in isolated regions through the design a hybrid renewable energy system (HRES) for Skyros, a Greek island not connected to the mainland grid. The proposed system integrates wind turbines, photovoltaics, pumped hydro, and hydrogen storage to ensure a stable supply, particularly during peak summer demand. Using advanced R simulations, three scenarios were analyzed on a 30 min basis. A combined storage system meets 99.99% of water demand and 83% of electricity needs. A pumped hydro-only system covers 99.99% of water demand and 74% of electricity needs. A hydrogen-only system supplies 99.99% of water demand but just 67% of electricity needs. The findings indicate annual CO₂ emission reductions exceeding 9600 tons. Economic analysis confirms the system’s feasibility, with a projected 10-year payback period. The cost of desalinated water is estimated at EUR 1/m³, while energy costs range from EUR 0.083/kWh for pumped hydro to EUR 0.093/kWh for hydrogen storage and EUR 0.101/kWh for the combined system. Overall, the results highlight the potential of hydrogen storage to enhance system flexibility and complement pumped hydro, offering sustainable water and energy solutions for isolated regions while addressing both environmental and economic challenges.

This research study examines a renewable energy system that has been designed to meet the water needs of Mykonos, a tourism-dependent island in Greece with high seasonal demand. The proposed system consists of 22 wind turbines of 2.3 MW each, 4 desalination units with a total capacity of 1400 m³/h and multiple pumped-hydro storage reservoirs with a total volume of 3,900,000 m³. Two operational scenarios were analyzed. Water production through desalination was prioritized in both scenarios; however, their difference lies in the way excess renewable energy has been allocated: that is either to storage or to electricity generation. The results indicate that water demand in Mykonos is almost fully met in both scenarios, reaching a coverage of 99.9%. However, there is a significant difference between the two scenarios regarding energy coverage, which corresponds to coverage rates of 73% and 79%, respectively. From an economic perspective, the marginal selling price of electricity is EUR/MWh 100 and the cost of desalinated water ranges from EUR/m³ 0.48 to 0.91 depending on the operating scenario. Overall, the results demonstrate nearly complete water autonomy in both scenarios, whereas the second scenario is proven optimal in terms of energy coverage. This approach proves that integrated water and energy management can lower fossil fuel use and improve sustainability on islands with strong seasonal variations.