Reliability and economic evaluation of energy storage as backup and load regulation power supply in data centers

The battery energy storage system (BESS) combines backup and load regulation functions, making it a potential alternative to the diesel generator (DG) as the backup power source for data centers. Some studies have been conducted on the reliability and cost–benefit of equipping data centers with BESS, but the impact of the reliability of external utility power and the expected outage losses have not been considered. Therefore, this study established a power supply reliability model that included the external utility power reliability and the electrical equipment reliability, and a cost–benefit model that took into account the BESS construction and replacement cost, the outage loss reduction, and the load regulation benefits. A case study was conducted on a data center in Beijing. The results indicate that: (a) the reliability and cost–benefit of BESS significantly vary with the reliability of the external utility power; (b) based on the 2022 utility power reliability data from various regions in China, in over 48% of the regions, the objective function value of BESS, the annual net income considering power outage losses, and the investment payback period are all superior to those of DG; and in over 27% of regions, the BESS–DG parallel system can serve as a suboptimal alternative to DG; (c) in regions with reliable utility power, BESS exhibits the potential as a feasible substitute for DG in providing backup and load regulation power to data centers.