After a long period of more than a decade, the 2,000 MW Subansiri Lower Hydroelectric Project, spread across the inter-state boundary between Assam and Arunachal Pradesh, has finally started partial power production.
The project achieved this milestone on Tuesday with the commissioning of Unit 2, after a delay of 13 years from the scheduled completion date in December 2012.
In a press note, NHPC has stated that the unit, with a capacity of 250 MW, was formally operationalized by the Union Power Minister, Manohar Lal, from New Delhi. This development symbolizes an important milestone in the operationalization of the largest hydro electricity project in India. Subansiri Lower Hydro Electric Project will have eight units of 250 MW each. After the operationalization of unit 2, another three will become operational soon with a capacity of 250 MW each. The remaining four will be completed by 2026-27.
Congratulating NHPC on this achievement, Union Power Minister Manohar Lal stated, “It is a ‘proud moment’ for NHPC, and indeed, for the entire nation, in the sense that this project has required ‘persistence, dedication, and teamwork’ on the part of NHPC, and it has been completed in record time, thereby fully reflecting the spirit of our ‘proud nation’.”
When completed, the Subansiri project is expected to increase the country’s renewable power generation capacity, ensure grid stability, and open up new vistas of power generation at an affordable cost. This run-of-the-river project with low pondage utilizes eight head race tunnels to transfer water for the generation of approximately 7,422 million units of renewable power every year.
NHPC also emphasized that the scheme will provide electricity to 16 beneficiary states in the country. Additionally, Arunachal Pradesh and the state of Assam will benefit from the arrangement since the two will get free electricity, and the whole northeastern part of the country will enjoy the allocated 1,000 MW.
In spite of this, the project involves a long journey of challenges. Initially, the project was expected to be completed in December 2012. However, various postponements of completion date were witnessed, with the latest being the final commissioning date fixed in May 2026. In fact, current approximations of the total cost of this project far exceed earlier ones, rising substantially over time from Rs. 6,285 crore, as approximated in 2002, to Rs. 26,075 crore when partially commissioned. The project, in its peak construction phase, offered direct jobs to about 7,000 local workers.
The Subansiri project has the biggest dam in Northeast India, which is a 116m-high concrete gravity dam, and it increases the infrastructure base in the region. The project utilizes state-of-the-art technology and has India’s biggest hydropower generator rotor, biggest stator, and main inlet valves. The project increases the power infrastructure base and provides jobs to the locals.
The project is imperative as it is the first in a series of cascades on the Subansiri river and is needed for flood control. The project has a dedicated flood cushion of 442 million cubic meters. The Subansiri project has a gross storage capacity of 1,365 million cubic meters and fills only one-third of its capacity to accommodate the water during flood periods. NHPC has implemented riverbank protection and erosion control on 30 km down to 60 km at an outlay of Rs 522 crores.
The construction of the Subansiri power project started in January 2005 after clearance of the forest in October 2004. The construction process had to be halted in December 2011, but the construction restarted in October 2019 after various committees formed by the Assam government and the Center reviewed the project.
The National Green Tribunal’s clearance of the power project finally enabled NHPC to restart the construction process on October 15, 2019, making way for its long-awaited inauguration. With Unit 2 of the project commissioned, the Subansiri Lower Hydroelectric Project finally takes a step towards realizing its promise of clean energy generation for the Northeast region of India.
