Hydrogen could play a pivotal role in protecting hybrid renewable plants from the economic drag of curtailment, according to new research from Italy’s University of Cagliari.
The team examined how adding a water electrolyzer to a floating photovoltaic–pumped hydro energy storage (FPV-PHES) facility can stabilize efficiency and cut the levelized cost of electricity (LCOE) when surplus solar output exceeds storage or grid capacity.
The study, published in the Journal of Energy Storage, modeled an FPV-PHES system on Sardinia that combines a 25 MW floating PV array with a pumped hydro installation using Francis turbines and multi-MW pumps across two reservoirs. Researchers simulated two operational modes: one allowing excess PV power to be exported to the grid, and another requiring all surplus energy to be absorbed on-site. They then introduced an anion exchange membrane electrolyzer, sized at about 15 MW, to convert curtailed electricity into green hydrogen.
Results revealed a stark difference between scenarios. Without an electrolyzer, system efficiency fell to just 24% under heavy curtailment, driving the LCOE up to $280/MWh. Incorporating hydrogen production improved performance dramatically, stabilizing efficiency at 61% and lowering LCOE to roughly $145/MWh. Hydrogen costs in the optimized case were estimated at $8.5/kg, providing an additional revenue stream while protecting the system’s economics from variability in grid access or storage limits.
Lead author Luca Migliari said the findings underscore the importance of sizing hybrid plants with curtailment in mind. By channeling otherwise-wasted energy into hydrogen, operators can hedge against revenue loss and strengthen project viability. The research team is now exploring complementary storage configurations and market mechanisms, such as flexibility services and price signals for electricity and hydrogen, to further enhance the resilience of PV-hydro hybrids facing high renewable penetration.
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