Development and optimal sizing of an integrated renewable energy system for sustainable cities

This study presents an integrated energy system aimed at promoting and supporting sustainable cities and communities through techno-economic and environmental optimization. The system is modeled using the REopt optimization tool developed by NREL and represents a multi-building campus comprising a large office, warehouse, primary school, supermarket, and a mid-rise residential building. The proposed scenario integrates photovoltaic (PV) systems, wind energy, battery energy storage (BES), chilled water thermal energy storage (TES), and grid interaction. The optimization framework evaluates system performance from energy, economic, and environmental perspectives in line with the source–system–service (3S) approach. The obtained results indicate that the optimized scenario reduces peak grid demand by approximately 30–35% through effective load shifting by energy storage and renewable energy integration. In the optimized scenario, the annual electricity demand of nearly 13 GWh is primarily supplied by the grid (67.3%), followed by PV generation (25.3%), battery discharge (7%), and wind energy. The battery system reaches a round-trip efficiency of 90.2%. The system prioritizes energy storage-based operation, reduces reliance on real-time electricity generation, and lowers operational costs. Environmental analysis reveals substantial emission reductions, including approximately 11,533 tonnes of CO 2 -eq, along with significant reductions in NO x , SO 2 , and PM2.5 throughout the system's life cycle. The overall system energy efficiency is found to be 23.57% on a source-to-service basis under the specified energy mix, with renewable energy and energy storage integration. The proposed system also supports urban decarbonization by reducing grid dependency and alleviating pressure on the existing electricity infrastructure.