Hydrogen can mitigate curtailment in floating PV-pumped hydro energy storage systems

<p class="p1"><span class="s1">Scientists at Italy’s University of Cagliari explored the integration of a water electrolyzer with a floating PV-pumped hydro energy storage system. They found that under high curtailment conditions, hydrogen production helped to stabilize system efficiency and lower the levelized cost of electricity when compared to a system without the electrolyzer.</span></p><p>Researchers from Italy’s <a href="https://www.pv-magazine.com/press-releases/fiamm-sodium-batteries-applications-and-advantages-of-environmentally-friendly-and-efficient-technology_100018722/" rel="noopener" target="_blank">University of Cagliari</a> have studied the integration of a water electrolyzer into a floating PV-pumped hydro energy storage (FPV-PHES) system, analyzing the system's efficiency and levelized cost of electricity (LCOE) under different curtailment levels.</p>
<p>The results appear in the research paper <a href="https://www.sciencedirect.com/science/article/pii/S2352152X25027100#s0010" rel="noopener" target="_blank">Green hydrogen generation for mitigating the impact of curtailment in floating photovoltaic &#8211; pumped hydro energy storage (FPV-PHES) systems</a>, published in the <em>Journal of Energy Storage.</em></p>
<p>“The novelty of our work is to show that the technical and economic issues caused by high renewable penetration also affect hybrid plants such as FPV-PHES if not sized by accounting for curtailment,” corresponding author Luca Migliari told <strong>pv magazine</strong>. “By integrating a highly flexible component such as an electrolyzer, these risks can be mitigated, as otherwise-curtailed electricity is turned into green hydrogen, and levelized costs become largely independent of curtailment conditions.”</p>
<p>The simulation was based on a PHES system installed on the Italian island of Sardinia. It included a Francis turbine, four 1.205 MW pumps and two 0.627 MW pumps. The upper reservoir is at an elevation of 55.45m to 118m, with the lower reservoir at an elevation of 38m to 45m. It is assumed to be operating under a typical meteorological year (TMY) for Sardinia, characterized by an average and maximum global irradiance (GI) of 0.2 kW/m2 and 1.1 kW/m2, respectively, and a yearly global irradiation of 1,758 kWh/m2.</p>
<p>The floating PV array used in the system features 500 W modules with a tilt of 10◦. The total capacity of the FPV system ranged from 0 MW to 25 MW in the study, with 25 MW being the main case study. Together with the PHES, this system was checked under two grid scenarios. The first saw all surplus FPV energy fed to the grid, while in the other scenario nothing was fed into the grid.</p>
<p>The study also tested adding an anion exchange membrane (AEM) with a capacity of 0-20 MW to the system, under the same grid scenarios. In the case study, the AEM size was around 15 MW. The PV energy management system prioritizes first PHES, then the AEM and lastly the grid, if allowed.</p>
<p>Migliari said the most striking finding was the dramatic contrast between scenarios. &#8220;Without the electrolyzer, efficiency may collapse to 24% and the LCOE rise to $280/MWh under high curtailment conditions. With the electrolyzer, efficiency stabilizes at 61%, LCOE at $145/MWh, and hydrogen can be produced at $8.5/kg,” Migliari said. “This demonstrates that hydrogen production not only creates an additional valuable output but also shields the system from curtailment risk.”</p>
<p>Migliari added that his research group will continue investigating strategies to mitigate curtailment risks from both a technical perspective and a market perspective. “On the technical side, we are studying different hybridization and storage options. On the market side, we are analyzing how electricity and hydrogen price formation, as well as revenues from flexibility services, can improve the profitability of PV hybrid systems,” he explained.</p>