NHPC Signs Agreement for 3,097 MW Etalin Hydroelectric Project in Arunachal Pradesh

NHPC Limited, India’s premier public sector hydropower developer, has entered into a Memorandum of Agreement (MoA) with the Government of Arunachal Pradesh to develop the massive 3,097 MW Etalin Hydroelectric Project. The project is designed as one of the largest power generation installations in the country.

1. Hydrology and Location of the Dibang Basin

The Etalin project is located in the Dibang Valley district of Arunachal Pradesh. The project is designed to utilize the flow of two major glacial rivers: the Dri River and the Tangon River. Both rivers are key tributaries that flow southward to join the Dibang River, which subsequently merges with the Lohit and Dihang (Siang) rivers to form the Brahmaputra River in the plains of Assam.

2. Run-of-the-River Schemes vs. Storage Dams

For geography and ecology questions, it is vital to differentiate the two primary designs of hydroelectric plants:

• Storage Schemes: Involve building a high dam to create a massive artificial reservoir. This stores water for year-round power generation but leads to extensive submergence of upstream forests and displacement of communities.
• Run-of-the-River Schemes: Divert a portion of the natural river flow through tunnels (headrace tunnels) to an underground powerhouse before returning the water to the river downstream. Because they do not require massive storage reservoirs, they minimize forest submergence, though they depend heavily on seasonal river discharge.

3. The BOOT Development Model

The Etalin project is being executed on a BOOT (Build, Own, Operate, and Transfer) model. Under this public-private partnership framework, the developer (NHPC) is responsible for financing, constructing, and operating the facility for a designated lease period (40 years from the commercial operation date). After the lease expires, the ownership and operations of the project are transferred back to the state government of Arunachal Pradesh free of cost.