Impact of Optimization Horizon on Techno-economic Performance of a PV-Driven Standalone District Cooling System

Department of Mechanical Engineering, National University of Singapore, 9 Engineering Drive 1, Singapore 117575, Singapore

^* Corresponding author: mpemdri@nus.edu.sg

Abstract

This study proposes a standalone photovoltaic (PV)-driven district cooling system integrated with multiple energy storage technologies, including battery storage, ice storage, and hydrogen storage. A techno-economic analysis is performed to optimize the system configuration and operation, with particular emphasis on the impact of the optimization horizon. The levelized cost of energy (LCOE) serves as the objective function, while component design and operational parameters are simultaneously optimized using a mixed-integer linear programming (MILP) approach. Key findings reveal that overly aggregated optimization horizons lead to underestimations of component capacities and LCOE. For instance, hydrogen storage is excluded when the optimization horizon is shorter than 90 days. However, extending the horizon beyond 90 days makes hydrogen storage essential to mitigate long-term solar energy scarcity. Furthermore, full-year optimization necessitates larger battery and ice storage capacities compared to aggregated time spans. The resulting LCOE under full-year optimization is 31.6% to 45.8% higher than those obtained using aggregated time spans, highlighting the importance of selecting an appropriate optimization horizon for accurate system design and cost assessment.