Commissioning event for the commercial operation of First Unit at Subansiri Lower hydroelectric project.

NHPC Limited has declared the commercial operation of the first generating unit, Unit-2 with a capacity of 250 MW, of the 2000 MW Subansiri Lower Hydroelectric Project on December 23, 2025. This development represents a key milestone for the largest hydropower facility in India.

The Subansiri Lower project is situated on the Subansiri River at Gerukamukh, along the border between Assam and Arunachal Pradesh. It is designed as a run-of-the-river scheme with small pondage and will achieve a total installed capacity of 2000 MW through eight units of 250 MW each.

The commercial operation of this initial 250 MW unit marks the beginning of incremental power addition to the national grid, contributing to enhanced stability in India's northeastern region. The virtual inauguration event involved senior government officials, including the Union Minister for Power and Housing & Urban Affairs.

The Union Minister described the commissioning as a significant achievement, stating that the project "symbolises India's commitment to clean and sustainable energy" and plays a role in advancing national clean energy objectives while supporting regional development and grid strengthening.

NHPC Chairman and Managing Director Bhupender Gupta said the project will "strengthen the national grid, support sustainable development in the Northeast and provide reliable renewable power to meet rising demand."

NHPC has indicated that three additional 250 MW units are scheduled for commissioning in the near future, with the remaining units to follow in phases through 2026–27. Upon full completion, the facility is projected to generate approximately 7,422 million units of renewable electricity each year on average.

As a run-of-the-river project, it incorporates measures for flood moderation, including a dedicated flood cushion within the reservoir to help manage water flow and protect downstream areas. NHPC has also completed extensive riverbank protection and erosion control works along the Subansiri River, extending up to 60 km downstream.

This step forward demonstrates progress in harnessing renewable resources through large-scale infrastructure. The project supports reliable power supply across multiple beneficiary states, including allocations for Arunachal Pradesh and Assam, and contributes to broader efforts to meet growing electricity needs with clean sources. The achievement highlights effective collaboration among various stakeholders to bring the long-planned development into operational phase.

by waterpowermagazine