Harnessing surplus photovoltaic power through an optimized alkaline electrolysis framework: pathways to green hydrogen in Italy 2030

Green hydrogen produced via renewable-powered electrolysis represents a key pathway for decarbonizing energy and industrial systems. Among available technologies, alkaline water electrolysis (AWE) is the most mature and cost-effective; however, its integration with intermittent renewable sources requires advanced load-flexible operation. This study develops a system-constrained framework to exploit surplus photovoltaic (PV) electricity in Italy for industrial-scale hydrogen production under projected 2030 conditions, aligned with the European Fit for 55 roadmap and an installed PV capacity of 80 GW. High-resolution PV data (TERNA, 15-min) projected to 2030 show generation ranging from 6.2–29.46 GWh/day, with operating durations of 6–14 h/day. Surplus PV is dynamically determined based on priority renewable dispatch, projected thermal generation, and minimum thermal plant operation (4.3 GWh), varying from 0.03 GWh in January to 9.56 GWh in May, remaining stable at 8.6–9.6 GWh during April–August, with peaks up to 11.1 GWh and weekend surpluses exceeding weekday values by 20–60%. A modular AWE system comprising up to nine parallel 20 t H2/hr trains enables flexible load-following operation with optimized thermal management. Hydrogen production reaches a maximum of 167.72 t H2/hr, peaking between April and June, with moderate output during the remaining months. Oxygen co-production ranges from 4.21 to 1341.75 t/day, while water demand up to 1509.47 m3/day. With electrolyzer efficiency of 58–68%, cell voltage of 1.8–2.0 V, and specific energy consumption of 48–52 kWh/kg H2, the framework enables precise hourly power allocation and scalable renewable hydrogen production