The Optimal Design of a Renewable Energy Production System Including Green Hydrogen Production to Support a Public Building

This study presents a mathematical programming approach for the optimal design of a renewable energy system in a grid-connected public building, incorporating green hydrogen production for surplus energy storage. The system includes wind turbines, solar panels, batteries, a hydrogen unit, and a grid connection. Hydrogen can also be sold as vehicle fuel, generating revenue and reducing the environmental impact. Unlike traditional hydrogen smart grid models that rely on continuous capacity variables—which often yield non-commercial fractional unit sizes—our MILP framework strictly enforces discrete equipment capacities matching real-world procurement specifications. The methodology is applied to the Chemical Engineering Department Building at the University of Patras, Greece, with two objectives: minimizing annual cost and minimizing carbon dioxide emissions. While higher grid electricity tariffs increase absolute total energy costs, they significantly enhance the economic competitiveness and payback of local renewable energy and green hydrogen installations, shifting the optimal system configuration toward self-sufficiency and deep decarbonization. Emission minimization achieves substantial reductions with acceptable economic trade-offs, mainly through hydrogen replacing fossil fuels in transport. A GAMS-based model demonstrates that integrating renewables and hydrogen storage can enhance energy security, lower costs, and reduce the environmental impact in public buildings.