PLN studies 1 GW seawater pumped storage project despite rising BESS competition
Wednesday, August 5 2026 - 03:50 PM WIB
By Pandu Setiabudi
State utility PT PLN is studying the development of a 1 GW seawater pumped hydro storage project in Puger, East Java, as part of its long-term energy storage strategy, even as the rapid expansion of battery energy storage systems (BESS) challenges the economics of pumped hydro projects.
PLN Director of Project Management and New & Renewable Energy Suroso Isnandar said on Wednesday that the proposed Puger project, which would be Indonesia's first seawater pumped storage facility, has not yet been included in the utility's 2025-2034 Electricity Supply Business Plan (RUPTL), although preliminary studies indicate strong potential.
PLN is currently developing some pumped hydro storage projects listed in the 2025–2034 RUPTL. The most advanced is the 1,040 MW Upper Cisokan Pumped Storage project, which is targeted to commence commercial operation (COD) in 2030. Other planned projects include the 500 MW Sumatra Pumped Storage, 943 MW Matenggeng Pumped Storage, 1,000 MW Grindulu Pumped Storage, and the 760 MW Jatiluhur Pumped Storage project to be developed by an independent power producer (IPP).
Suroso said pumped hydro storage was initially envisioned as a key solution to address the intermittency of renewable energy, particularly solar power, whose share in Indonesia's electricity system is expected to increase significantly. However, the rapid development of Battery Energy Storage Systems (BESS) has made the economics of pumped hydro projects increasingly challenging.
Nevertheless, he stressed that BESS cannot fully replace pumped hydro storage. Pumped hydro provides system inertia, or mechanical inertia, which plays a critical role in maintaining grid frequency stability during disturbances. This inertia gives system operators valuable time to respond and mitigate disruptions, reducing the risk of widespread outages.
"Therefore, the development of pumped storage projects will continue, both by PLN and by independent power producers," he said.
Suroso added that Indonesia's major power system blackout in 2019 underscored the importance of maintaining adequate system inertia, reinforcing the role of pumped hydro storage as an essential technology for supporting the integration of renewable energy into the national grid.
Editing by Reiner Simanjuntak