Electricity balancing for resilient 100% renewable energy systems on islands: Imported e-fuels versus domestic e-hydrogen on the case of Mauritius

Globally, islands showcase many challenges and opportunities posed by defossilisation of energy systems. For small island energy systems in the Indian Ocean and beyond, the seasonality of variable renewable energy supply, with tourism-induced seasonal variability in energy demand make power balancing increasingly challenging. Hydrogen is a promising energy carrier for power balancing, but the need for low-cost technology, suitable storage, and skilled labour can make hydrogen use in remote islands problematical. To assess the value of domestic hydrogen production, and using Mauritius as an example, this study presents a novel contribution by evaluating an alternative balancing approach via imported e-fuels as an e-hydrogen alternative. Optimum energy systems for the year 2050 are configured for multiple clusters of e-fuel imports and domestic hydrogen production scenarios, varying the land area use for ground-mounted solar photovoltaics. By limiting ground-mounted solar photovoltaic installations to 1.45% of land area, two alternative domestic hydrogen production systems are configured. Results indicate that dedicated wave power and a hybrid wave power system with floating offshore solar photovoltaics achieve lower levelised cost of electricity of 83.3 €/MWhel and 59.8 €/MWhel, respectively, compared to the reference system at 89.6 €/MWhel. The e-fuel import scenarios yield a minimum levelised cost of electricity of 99.4 €/MWhel, however, they increase exposure to global market variations and supply chain dependencies. Conversely, domestic e-hydrogen production offers energy resilience through fully localised balancing. The methodological framework and insights are transferable beyond Mauritius, offering a novel approach to optimising resilient energy systems for small islands.