Hydroelectric Power in India: Factors, Challenges and UPSC Notes (UPSC Environment)

Hydroelectric power uses the potential energy of falling or fast-flowing water to turn turbines and generate electricity. It is the only large-scale renewable energy source that can ramp up or down in minutes, making it essential for grid flexibility. India has an identified hydro potential of 1,45,320 MW, of which only about one-third is installed, leaving a significant unexploited resource, particularly in the Himalayan river basins. After the Teesta-III disaster of 2023 and the revival of pumped storage projects, hydropower is back at the centre of UPSC GS Paper III discussions on energy and environment.

What is hydroelectric power

Hydroelectric power is generated by running water through turbines connected to generators. It is an independent, site-specific source of energy. Generation occurs in two forms:

• Storage-type projects with pondage or reservoirs that can regulate flows (multipurpose dams, Pumped Storage Projects).
• Run-of-the-river projects that use natural river flow without significant storage (common in mountainous regions).

Ancient civilisations used water power for grinding grain and driving industrial machinery. Three modern inventions made hydropower generation of electricity possible:

• Hydro turbine (Pelton, Francis, Kaplan).
• Dynamo/electric generator (Faraday, later Edison and Tesla).
• Cement for large dams, enabling concrete gravity and arch structures.

Factors affecting development of hydroelectric power

Head of water

A height difference between intake and turbine (the "head") is essential. Naturally occurring waterfalls, rapids and canyons are preferred. Examples: Alps, Scandinavia, Rocky Mountains. Rivers with massive discharge but low gradient are viable too, such as the Volta in Ghana. Many countries possess fall lines, the edge where mountain streams drop to coastal plains, such as on the eastern side of the Appalachians. Artificial dams create head through impoundment.

Large volume of water

Power generation is proportional to water volume passing through turbines. Rivers with large discharge such as the Nile, Indus and Zaire (Congo) are attractive.

Regular and reliable supply

Continuity and low fluctuation are important. Perennial rivers are preferred. Long droughts in monsoon-dependent regions, frozen winters in temperate latitudes and Mediterranean summers can reduce discharge. Dams smooth out seasonal variability.

Presence of lakes

Natural lakes along rivers reduce the need for artificial reservoirs. Corries and ribbon lakes in glaciated areas (Swiss and British Lake District) exemplify this. In India, natural reservoirs are less common.

Space for reservoir

Suitable lake creation requires terrain that doesn't destroy agriculture, settlements or forests. Gorges have natural advantages: deep walls, steep slopes, large storage capacity and usually no competing land use.

Large market

Because electricity is difficult to store and transport over very long distances, there must be a ready market. Alternative fuel availability matters too. In multipurpose schemes, power is often the minor component; irrigation, drinking water and flood control dominate.

Heavy capital outlay

Land acquisition, rehabilitation, dam erection, powerhouse, transmission, and round-the-year maintenance make initial costs very high. Hydro projects are typically undertaken by governments (CPSUs like NHPC, SJVN, THDC) or through PPP, especially for multipurpose schemes.

Pumped Storage Projects (PSPs)

PSPs are the Indian grid's new frontier.

• Two reservoirs at different elevations.
• Pump water up during off-peak hours (using excess solar).
• Release water down through turbines during peak demand.
• Act as giant grid-scale batteries.

India targets 60 GW of PSP by 2030 under the Ministry of Power framework. Greenko, JSW, NHPC and Adani are active. Pinnapuram (Andhra Pradesh), Sharavathy and Kadamparai are key projects.

Hydropower in India

Installed capacity

As of 2024, India's installed hydro capacity was about 47 GW (large hydro) plus about 5 GW of small hydro. Identified potential exceeds 1,45,320 MW. Key stations include Tehri (2,400 MW), Koyna (1,960 MW), Nathpa Jhakri (1,500 MW), Sardar Sarovar (1,450 MW), and Bhakra-Nangal (1,325 MW).

Geographic concentration

Himalayan rivers (Ganga, Brahmaputra, Indus basins) hold the largest remaining potential. North-East India alone accounts for 34 percent of India's unexploited hydro potential, concentrated in Arunachal Pradesh.

Hydro Purchase Obligation (HPO)

Introduced in 2022 by the Ministry of Power, HPO mandates discoms to source a specified share of electricity from large hydro, effectively creating a demand signal for new projects.

Hybrid annuity model

New projects under HAM structure share risk between developers and government, reducing financing costs.

Environmental and social concerns

• Biodiversity loss and ecosystem disruption.
• Displacement and rehabilitation: Often incomplete for tribal communities.
• Reservoir-induced seismicity: Koyna (1967, magnitude 6.3).
• Glacial Lake Outburst Floods (GLOFs) destroyed the Teesta-III dam in October 2023.
• Sediment trapping affects downstream deltas.
• Methane emissions from anaerobic decay in tropical reservoirs.
• Downstream hydropeaking disrupts ecology.
• Dam safety: Addressed under the Dam Safety Act, 2021.

Climate change and hydropower

Glacier retreat in the Himalayas is changing the baseline flows on which hydropower design was based. Extreme rainfall events and GLOFs raise safety risks. Integrated basin planning, climate-resilient design, and cumulative environmental impact assessment are increasingly essential.

Latest developments (2024-26)

• Teesta-III disaster (October 2023): GLOF from South Lhonak Lake destroyed the 1,200 MW project and killed over 90 people, prompting a review of hydro siting in glacial zones.
• Dam Safety Act 2021 implementation: The National Dam Safety Authority (NDSA) issued binding inspection protocols in 2024.
• Pumped Storage push: About 25 GW in various stages of bidding and construction by early 2026.
• Hydro Purchase Obligation tightened in 2024 with trajectory up to 2029-30.
• Subansiri Lower (2,000 MW) commissioning underway after long delays.
• Polavaram Project: Multipurpose dam on Godavari crossing multiple deadlines; Cabinet re-approved revised cost in 2024.
• COP29 Baku (2024): India's updated NDCs reaffirmed hydropower as essential to the 500 GW non-fossil capacity target and climate resilience.
• Great Nicobar Project: Associated power infrastructure under scrutiny by Parliamentary Standing Committee on seismic risk (2024).
• Green Energy Open Access Rules (2022): Applied to large hydro developers for bilateral power sale contracts.

UPSC Relevance

Prelims focus

• Installed hydro capacity and identified potential (1,45,320 MW).
• Major hydro stations (Tehri, Bhakra-Nangal, Nagarjuna Sagar, Sardar Sarovar).
• Pumped Storage Projects framework and 60 GW target by 2030.
• Hydro Purchase Obligation (2022).
• Dam Safety Act 2021.
• CPSUs: NHPC, SJVN, THDC India Limited, NEEPCO.

Mains focus (GS III)

Typical question framings evaluate the case for and against new hydropower in the Himalayas after Teesta-III, the role of PSPs in renewable integration, the environmental and social costs of large dams, and climate-resilient design. Strong answers cite specific projects, the Dam Safety Act 2021, GLOF risk, and international comparisons.

Linkages

Hydropower connects to SDG 7, SDG 13, India's updated NDCs after COP29, the Dam Safety Act 2021, the Forest (Conservation) Amendment Act 2023, the Biological Diversity Amendment Act 2023 (for submergence), the Right to Fair Compensation Act 2013, and the Green Hydrogen Mission for renewable integration.

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