Economic and Socio-Environmental Benefits of Utilizing Existing Reservoirs for Brownfield Pumped Storage Development in Indonesia

Abstract

Pumped storage hydropower (PSH) is a critical technology for supporting renewable energy integration and long-duration energy storage. In Indonesia, where numerous multipurpose reservoirs already exist, brownfield PSH—developed by reusing an existing lower reservoir—offers a promising alternative to conventional greenfield construction. This study evaluates the economic and socio-environmental benefits of brownfield PSH using the Upper Cisokan Pumped Storage (UCPS) project as a representative reference case. A two-stage methodology is applied, consisting of a global literature review and a quantitative economic assessment based on engineering and cost data from the UCPS Project Appraisal Document.

The analysis demonstrates that brownfield PSH significantly reduces new land disturbance, environmental impacts, and social disruption by eliminating the need for a new lower reservoir. Using the Height × Area method to allocate dam construction costs, the avoided lower-dam civil works amount to US$90.14 million. Reuse of an existing reservoir also reduces land acquisition and resettlement requirements, yielding an additional saving of US$56.9 million. Furthermore, removing the lower-dam construction shortens the critical-path schedule by 18 months, resulting in US$33.36 million in avoided indirect EPC costs and US$8.98 million in reduced interest during construction. In total, brownfield development provides an estimated economic benefit of US$189.38 million, equivalent to approximately 25% of total project cost.

Beyond economic gains, brownfield PSH yields substantial socio-environmental advantages, including reduced habitat loss, fewer resettlement pressures, lower permitting risk, and minimal riverine impacts due to closed-loop configurations. These findings highlight the strong potential of reservoir-based brownfield PSH as a sustainable and cost-effective pathway for advancing Indonesia’s energy-storage infrastructure.