Comparative Assessment of Battery Energy Storage and Pumped Hydroelectric Storage for Small and Large Scale Renewable Energy Applications

The total energy demand is alarmingly increasing in recent times. The primary objective of power system operators is to reliably meet electricity demand while maintaining system stability in a cost effective manner. The increasing penetration of solar photovoltaic (PV) generation has intensified the reliance on battery energy storage systems (BESS) to manage intermittency and demand supply mismatch. However, large scale battery deployment introduces challenges related to cost, degradation, limited lifetime, and grid stability. This paper presents a comparative cost analysis of Battery Energy Storage Systems (BESS) and Pumped Hydroelectric Storage (PHES) integrated with solar-based renewable systems to determine the most suitable option in terms of plant capacity. Excess solar energy available during low demand daytime periods is utilized to pump water to an upper reservoir, thereby storing energy in the form of gravitational potential. During evening and night time peak demand, when solar generation is unavailable, the stored water is released to generate electricity. The comparative assessment incorporates the levelised cost of storage (LCOS), degradation related lifecycle cost for BESS, and life cycle carbon emission cost for both technologies. Results reveal a capacity dependent transition, with BESS preferred up to 45 MW, PHES environmentally favourable between 45–51 MW, and PHES economically and environmentally superior beyond 51 MW.