Energy storage for a flexible and decarbonized power system in China: Pathways and regional deployment

The power system transition is central to achieving China's dual‑carbon targets of carbon peaking by 2030 and carbon neutrality by 2060. The rapid expansion of variable renewable energy (VRE) has made pumped hydro storage (PHS) and battery energy storage systems (BESS) critical flexibility resources for integrating high shares of VRE and supporting power system balancing. This study is motivated by the need to coordinate PHS and BESS development with China's evolving regional flexibility requirements. This study employs the SWITCH-China model, a linear programming framework that integrates long-term capacity expansion and short-term operational dispatch. The model optimizes energy storage deployment pathways across alternative development scenarios by minimizing total system cost, including investment, operation, and transmission costs, while accounting for regional power demand, carbon emission constraints, and power system operational constraints. The results show that by 2050, China's installed energy storage capacity reaches 1000–1200 GW, with an energy capacity of approximately 2220–3340 GWh. PHS leads energy storage expansion in the early and middle stages of the transition, whereas BESS becomes the main driver of additional deployment in the later stage. Energy storage demand also exhibits pronounced regional heterogeneity: North China requires the largest deployment, while Northeast China requires the least, reflecting differences in VRE resource endowments, load-balancing pressure, and interregional power transmission. At the provincial grid level, PHS mainly provides capacity support and sustained regulation, whereas BESS is better suited to short-duration balancing and flexible system regulation. This study offers policy-relevant insights into the coordinated deployment and operation of storage technologies during China's power system transition.