Dynamic energy flexibility and economic viability of solid-state hydrogen as a hybrid energy storage strategy for buildings

Recognizing the importance of integrated energy storage systems in improving the reliability of renewable energy applications in buildings, the present study explores the energy flexibility and techno-economic feasibility of solid-state hydrogen and battery as a hybrid storage solution for solar-powered buildings. To rigorously examine the short- and long-term response flexibility of the dual-level storage system, a benchmark case study is evaluated under both extreme monthly (and seasonal) load variations and relatively stable year-round demand conditions. A coupled dynamic simulation model is developed in TRNSYS, integrating a custom-coded solid-state hydrogen component and the building load data from the OpenStudio/EnergyPlus plugin, ensuring realistic representation of demand-side dynamics and electrical loads. A statistical multi-objective algorithm optimizes component sizing of the hybrid system by identifying optimal design parameter combinations at each self-sufficiency level while minimizing system life-cycle cost. The dynamic energy performance analysis elucidates the interdependence between metal hydride and battery storage systems across multiple temporal horizons, revealing distinct patterns in the seasonal and monthly distribution rates under different scenarios. A detailed techno-enviro-economic analysis enables the evaluation of the interplay between the renewable energy factor and key performance indicators. A sensitivity analysis revealed that, on average, a 10% increase in the renewable factor raises the life-cycle cost by 25.4% to 38.4%, depending on the scenario. It is shown that for the self-sufficiency levels ranging from 70% to 100%, the levelized cost of electricity (LCOE) spans from 96 to 274 $/MWh. At the off-grid configuration, projections imply a potential reduction of the levelized cost of hydrogen (LCOH) by up to 45.4% over the next two decades, reaching values between 3.34 and 4.42 $/kg. • Energy flexibility of a PV-powered building with dual-level energy storage is assessed. • Multi-objective optimization yields minimal-cost sizing for diverse renewable targets. • A dynamic interaction between the renewable factor and economic aspects is observed. • A 10% increase in the self-sufficiency rate raises levelized cost by an average of 17.5%. • Dynamic analysis captures hydrogen–battery interplay across multi-temporal horizons.