Green hydrogen from floating PV: Water conservation and energy nexus in Basilicata (Italy)

This study explores the potential for green hydrogen production through floating photovoltaic (FPV) systems installed on artificial water reservoirs in Basilicata, southern Italy. FPV systems provide a dual benefit: they generate renewable electricity while simultaneously reducing water evaporation through surface shading, contributing to water conservation. After suitable treatment to meet PEM purity requirements, the water preserved from evaporation is supplied as feedwater to a proton exchange membrane (PEM) electrolyser powered entirely by the FPV system. In this way, FPV coverage simultaneously determines both the water available for electrolysis and the renewable electricity needed for hydrogen production. Five reservoirs located in the Basilicata region were analysed to assess their technical and economic potential for hydrogen production. Several scenarios were evaluated by varying the percentage of FPV surface coverage and the operating strategy of the electrolyser. Results show that covering 50% of the reservoir surface can significantly reduce annual evaporation, preserving an equivalent water depth approximately 1250 mm of water per year in the reference reservoir and about 1000–1100 mm of water per year across the other sites, while also generating about 55 GWh/y. Under variable-load operation, hydrogen production reaches nearly 952,6 tons per year for the reference reservoir, with a combined potential exceeding 6800 tons annually across all five sites. The water required for electrolysis represents less than 3% of the total water conserved. Economic analysis indicates that the most cost-effective configuration achieves a Levelized Cost of Hydrogen of about 7.4 €/kg, in line with international targets for renewable hydrogen competitiveness. These results highlight the potential of FPV-based hydrogen systems as an integrated water–energy solution for Mediterranean regions. • Floating PV reduces reservoir evaporation by up to 71%. • Evaporation savings supply water for green hydrogen production. • FPV-powered PEM electrolysis enables large-scale renewable H 2 . • Over 6800 t/y of green hydrogen potential in Basilicata reservoirs. • Cost-effective hydrogen achieved with LCOH as low as 7.4 €/kg.