UC Merced

Green hydrogen is widely recognized as a promising energy carrier that enables deep decarbonization and integrates variable renewable energy sources. However, its large-scale deployment remains constrained by high production costs and operational challenges associated with intermittent renewable electricity.This thesis presents an hourly techno-economic analysis of green hydrogen production in off-grid hybrid solar–wind systems directly coupled to electrolyzers, without battery storage or grid interaction. To determine the drivers of cost, the study focuses on the impact of renewable resource complementarity and electrolyzer sizing on hydrogen production cost. An hourly modeling framework (8760 h) was developed to simulate renewable electricity generation, electrolyzer operation, hydrogen production, and the Levelized Cost of Hydrogen (LCOH). Renewable generation profiles are obtained using the System Advisor Model (SAM), while a custom model evaluates electrolyzer performance under operational constraints and variable electrolyzer-to-renewable capacity ratios (R). The framework is applied across a diverse matrix including four representative U.S. locations spanning solar-dominant, wind-dominant, low-resource, and highly complementary resource conditions; five renewable energy configurations ranging from PV-only to wind-only systems with hybrid solar–wind combinations; three electrolyzer technologies (AWE, PEM, and SOEC); and electrolyzer-to-renewable sizing ratios ranging from 0.2 to 1.The results reveal that LCOH exhibits a convex relationship with R, confirming the existence of an optimal sizing point driven by the trade-off between renewable curtailment and electrolyzer utilization. It was found that the electrolyzerto-renewable sizing ratio strongly influences electrolyzer capacity factor, curtailed energy, hydrogen production, and overall system economics. Among the evaluated locations, Amarillo–Texas achieves the lowest LCOH (5.61 USD/kg) for a PEM electrolyzer coupled to a hybrid PV45–WD45 configuration, highlighting the benefits of solar–wind complementarity. While hybrid systems generally improve electrolyzer utilization and reduce LCOH in locations with balanced solar-wind resources, while PV-only systems remain optimal in solar-dominant regions such as Phoenix–Arizona. Among the technologies studied, PEM consistently provides the lowest LCOH among the evaluated electrolyzer technologies.Sensitivity analyses indicate that renewable energy and electrolyzer capital costs are the dominant drivers of LCOH reduction. Under cumulative cost reduction scenarios, substantial decreases in both renewable and electrolyzer CAPEX are required to approach low-cost hydrogen targets, while renewable resource quality remains a fundamental determinant of system economics. Overall, the results demonstrate that the economic viability of green hydrogen depends not only on cost reductions, but also on optimal system design, electrolyzer sizing, and renewable resource complementarity. This work highlights the importance of integrated hourly techno-economic modeling for identifying cost-effective renewable hydrogen production under variable renewable energy conditions.