NHPC Limited launched India’s largest hydropower project test run on October 24, 2025. The wet commissioning targets the 2000 MW Subansiri Lower facility at Gerukamukh. Officials oversaw the turbine checks for the first 250 MW unit. The event marks a revival after a 14-year delay. It promises cleaner power for millions.
This advance bolsters India’s renewable targets. South Asia eyes the output. Arunachal and Assam gain jobs and supply. Yet border sensitivities with China linger. Hydropower eases fossil fuel reliance. Regional grids strengthen. Economic ties deepen via shared rivers.
Subansiri Lower Test Run Kicks off Commissioning Phase
Engineers initiated the Subansiri Lower test run with water flow trials. The process verifies turbine performance sans power output. NHPC teams monitor vibrations and seals. Results guide full grid sync.
Bhupender Gupta, Chairman and Managing Director of NHPC, attended the launch. He praised the feat. “This achievement is more than a project milestone,” Gupta said. “It is a symbol of India’s unstoppable march towards a cleaner, greener and self-reliant energy future.” His words highlight national pride.
India’s largest hydropower commissioning involves eight 250 MW units. Four stand ready for trials. Completion adds 1000 MW this year. Annual yield hits 7500 GWh. That equals power for 1.5 million homes.
The NHPC spokesperson explained the step. “Wet commissioning is basically a test run of the turbine to check several parameters without generating electricity,” the official noted. “The test run with water flow may take four to five days.” Precision ensures safety on the Subansiri River.
Arunachal Subansiri Project Wet Run Revives Stalled Dream
The Arunachal Subansiri project wet run resumes work halted in 2011. Protests cited flood risks to the Assam plains. Activists feared downstream havoc. NHPC paused construction amid unrest.
Resumption came in October 2019. The Prime Minister’s Office urged progress. Enhanced safeguards followed. Seismic studies and eco-flows addressed concerns. Local pacts secured buy-in.
The start of Subansiri 2000 MW power generation nears. Unit one leads the pack. Synchronization follows tests. Grid linkage via 400 kV lines reaches Assam and beyond. North East states are the top beneficiaries.
Gupta thanked stakeholders. He nodded to the governments of Arunachal and Assam. “Extended heartfelt thanks to the Ministry of Power, Govt. of India, Governments of the State of Arunachal Pradesh and Assam,” he stated. Partners such as BGS-SGS-SOMA and GE Vernova assisted with the execution.
Sanjay Kumar Singh, Director of Projects, lauded the team. “Commended the project team for their commitment and technical excellence,” per NHPC records. Suprakash Adhikari, Director Technical, urged speed on rest. “Encouraged the team to sustain the same zeal for the timely commissioning of the remaining units.”
India’s Largest Hydropower Project Commissioning Eyes Regional Impact
India’s most significant hydropower project undergoes test run, fueling expansion. Installed capacity is expected to climb to 47 GW by 2030. Hydropower shares 12% now. Subansiri lifts that slice.
Costs topped INR 28,000 crore. Funding is divided between the public and private sectors. NHPC holds the majority. Delays inflate budgets by 50%. Yet, it returns a promise of 8% IRR over 40 years.
Environment weaves in. The dam spans 235 metres high. The reservoir covers 38 sq km. Fish ladders aid migration. Sediment flushing curbs silt. Assam monitors flows yearly.
China’s upstream dams draw scrutiny. Beijing built 60 GW on the Brahmaputra. India counters with run-of-river designs. Diplomacy stresses data sharing. Subansiri bolsters leverage.
Assam Chief Minister Himanta Biswa Sarma welcomed the news. His office flagged eco-measures. “Vital for sustainable development,” a statement read. Arunachal leaders echoed support.
Background: Delays to Determination
Approval hit 2003. Tenders followed in 2005. Ground broke in 2006. Protests peaked in 2011. Over 100 groups rallied. Fears of 10-metre floods gripped Dhemaji.
Talks dragged into 2018. NHPC invested INR 10,000 crore pre-halt. Resumption tied to clearances. The Centre formed panels. Green nods arrived in 2019.
The pandemic slowed the pace. Monsoons tested sites. Yet, 95% of the civil works are complete. Electro-mechanical nears 80%. Milestone cements resolve.
What’s Next: Full Power Ahead
Trials wrap next week. Unit two queues up. Full ops target March 2026. Output splits are 70% Assam and 30% Arunachal. Exports to Bhutan are possible.
Policy aids. Viability gap funding unlocks INR 5000 crore. Private bids eye more sites. South Asia integrates via the BBIN grids.
India’s largest hydropower project test run sets pace. It channels river might into progress. Grids will glow brighter soon.
Published in SouthAsianDesk, October 29th, 2025
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