PNNL

Abstract

Grid energy storage is essential for maintaining the delicate balance of electricity supply and demand, with Battery Energy Storage Systems (BESS) emerging as an important asset in grid applications. This study focuses on exploring the promising applications of iron-nickel (Fe-Ni) batteries in grid energy storage, and evaluates the performance of Fe-Ni batteries under different operational conditions. The results demonstrate their capability for participating in frequency regulation (FR) services, maintaining grid frequency stability through rapid charge and discharge cycles. Remarkably, Fe-Ni batteries exhibit resilience to overcharging and are capable of operating at high SOC levels, even up to 100%. This capability empowers the battery has maximum stored energy available and provides a better cushion for emergencies or unexpected power shortages. The efficiency and capacity of Fe-Ni batteries vary with initial SOCs during FR tests, emphasizing the importance of selecting an optimal SOC for specific applications and implementing appropriate charging strategies. Additionally, this research unveils that, following an extended period of FR service (e.g., 250 days), the degraded Fe/Ni batteries can be reset to their original state via full charge/discharge, which is evident through the observation of various battery parameters including resistance, voltage, etc. The research also assesses Fe-Ni batteries' suitability for peak shaving (PS) applications, confirming their stable and reliable performance under various load conditions and discharge rates. The extensive cycling tests conducted in this study underscore the compelling potential of Fe-Ni batteries for grid-scale energy storage applications.