ITANAGAR, 23 Dec: State-owned NHPC commenced commercial operation of the second unit (250 mw) of the 2,000 megawatt (mw) Subansiri Lower Hydroelectric Project (SLHEP) on Tuesday, marking a significant step in commissioning India’s largest hydropower project.
Union Power Minister Manohar Lal inaugurated the commercial operation of Unit 2 of the project through the virtual mode.
The minister lauded the achievement as a proud milestone in the NHPC’s journey.
“The commissioning of this unit is not just a technical achievement, but a testament to years of hard work, dedication, and teamwork,” he said.
The minister said that project stands as a symbol of India’s commitment to clean and sustainable energy, supporting Northeast India’s growth, strengthening the national grid, and advancing India’s ambitious net zero goals.
Power Secretary Pankaj Agarwal lauded the NHPC’s achievement, saying that the Subansiri Lower project would greatly improve energy supply in the Northeast and serve as a testament to India’s commitment to state-of-the-art, sustainable power systems.
Agarwal emphasised on timely commissioning of the remaining units, noting that the project would continue to play a pivotal role in India’s transition to a net zero energy future while generating substantial socioeconomic benefits for local communities.
NHPC CMD Bhupender Gupta said that the project would strengthen the national grid, support sustainable development in the Northeast, and provide reliable renewable energy to meet growing demand. He expressed gratitude to the Ministry of Power, the governments of Arunachal Pradesh and Assam, former NHPC leaderships, the entire Subansiri project team, all key stakeholders, and partners for their dedicated support in achieving this milestone.
SLHEP Executive Director Rajendra Prasad affirmed that the project team is fully committed to achieving commissioning of the remaining units of the project as per the stipulated schedule.
“With the commissioning of Unit 2, the project is moving swiftly towards commissioning of three more units of 250 mw each shortly, followed by phased commissioning of the remaining four units during 2026-27,” the NHPC stated in a release.
Upon full commissioning, the SLHEP will boost India’s renewable energy capacity, enhance national grid resilience and usher in a new era in massive clean energy contribution, it said.
Apart from supplying electricity to 16 beneficiary states across India, the project will provide free power allocations to Arunachal and Assam, while the Northeast region will receive 1,000 mw from the project, significantly strengthening regional energy availability, the release said.
The SLHEP comprises eight units of 250 mw each, and is designed as a run-of-the-river project with small pondage, diverting water through eight head race tunnels to generate 7,422 million units of renewable electricity annually, contributing significantly to India’s green energy future.
The project features the largest dam in Northeast India: a 116-metre high concrete gravity dam which not only strengthens regional infrastructure and grid resilience but also enhances flood moderation and water management in the Subansiri river basin, the release said.
The SLHEP is a showcase of engineering excellence and determination, housing India’s heaviest hydro generator rotors, largest stators and biggest main inlet valves, it said.
The project also features pioneering construction innovations, including the nation’s largest aggregate processing plants, the highest-capacity batching plant and the first-ever use of Rotec’s tower belt for dam concreting in India, underscoring the NHPC’s commitment to technological advancement in large-scale hydropower development, the release said.
It is the first of the cascaded dams on the Subansiri river and plays a critical role in flood moderation.
The project provides a dedicated 442 million cubic metre flood cushion for safer management during the monsoon season.
With gross reservoir storage of 1,365 million cubic metres at full reservoir level, the project ensures that approximately one-third of the reservoir remains empty during flood periods, enabling it to absorb excess floodwaters and protect downstream communities, it stated.
The NHPC stated also that it has implemented extensive riverbank protection and erosion control measures along the Subansiri river, completing works up to 30 km downstream and extending them up to 60 km with an investment of about Rs 522 crore.
It also stated that the project has generated strong socioeconomic benefits for the region by engaging around 7,000 local people daily during its construction phase and creating numerous direct and indirect jobs through contractors, service providers and local markets.
Additionally, the project is expected to boost tourism and enhance river navigation, contributing to long-term regional development and prosperity.
The NHPC has invested around Rs 155 crore in CSR initiatives across Arunachal and Assam, the release said, adding the with the commissioning of the project and the availability of continuous power, new small-scale industries are expected to emerge, further expanding employment and business opportunities while helping reduce outmigration.
