NHPC's Subansiri Lower Project Set to Begin Power Generation

Despite prolonged disputes, protests, and controversies, the National Hydroelectric Power Corporation (NHPC) has finally made the mega Lower Subansiri Hydroelectric project ready for power generation. NHPC’s Chairman and Managing Director, Raj Kumar Chaudhary, made this announcement during a media interaction in Delhi.

Responding to a query regarding NHPC’s contributions to power generation and the country's economic growth, Chaudhary stated, “The time has come to operationalize the Lower Subansiri Hydroelectric Project. We are attempting to commission the project by March-April, with the first phase of power generation beginning on April 11.”

An official source from the NHPC informed that from March, the project will start generating a total of 750 MW of hydroelectric power by operating turbines in three units at the powerhouse. The hydroelectric project is now fully prepared, added the source. The dam has been equipped with nine gates, and the reservoir currently holds water at a height of 51 feet from the river’s surface. The target is to accumulate water up to a height of 205 feet, though power generation will be feasible once it reaches 190 feet. NHPC aims to reach this water storage milestone by March this year.

Challenges During Construction

While no major political or organizational protests have disrupted the construction over the past five years, the project faced significant challenges due to environmental factors. Heavy floods and landslides in 2020 delayed the initial power generation timeline, which was pushed from March 2020 to August 2022. However, due to continued landslides and adverse weather conditions, the deadline kept shifting further.

Between 2021 and 2023, the project suffered considerable financial losses due to 39 instances of devastating floods and landslides. In October 2023, a severe landslide at the project site blocked the No. 1 diversion tunnel, causing the riverbed to dry up completely.

2024 - A Favourable Year for NHPC

NHPC officials believe that 2024 has been the most favorable year for the project. Unlike previous years, the dam did not face any flood-related damages. Additionally, a prolonged dry spell between July and mid-September 2023 caused the Subansiri River’s water level to drop abnormally. This unexpected dry period allowed NHPC to continue construction work at full pace, leading to significant progress.

During this period, NHPC installed three additional gates in the dam and successfully placed large generators in the powerhouse, along with two turbines. By February 2024, the third turbine was also installed, allowing NHPC to initiate power generation across three units, each producing 250 MW, totaling 750 MW in March.

Originally, the cost of constructing the hydroelectric project was estimated at Rs 6,285 crore in 2002. However, due to repeated natural calamities and delays, the total budget escalated to Rs 21,247 crore by December 2022. By March 2022, NHPC had already spent approximately Rs 19,000 crore on the dam's construction. The overall operational cost is expected to reach Rs 20,834 crore by the end of 2024.