Mumbai: A month before the climate summit COP26 began in Glasgow, more than 300 organisations across 69 countries urged governments not to use climate funds for "false climate solutions" such as new hydropower dams. They urged that these dams be removed from all the Nationally Determined Contributions (NDCs) targets pledged under the 2015 Paris Agreement that aim to combat global warming.

The appeal included 26 environment groups from India, which has been promoting hydropower projects in the belief that they are clean and sustainable. Environmentalists point to studies (here and here) conducted in the past decade that have shown that hydropower dams are major emitters of methane, a greenhouse gas 28-34 times more potent than carbon dioxide.

In 2019, India declared large hydropower plants as "renewable energy" resources--earlier, only projects smaller than 25 MW were deemed as renewable energy resources--thereby providing incentives to developers such as easier debt repayment terms and funding for associated infrastructure like roads and flood defenses. In August 2021, the environment ministry also recommended restarting the construction of seven under construction hydropower plants in Himalayan region that had been halted for various reasons.

Experts have, however, pointed out that hydropower dams pollute and also precipitate natural disasters. "The idea of clean, green, sustainable hydropower, as an alternative to coal, has no truth to it," said Himanshu Thakkar from the South Asia Network on Dams, Rivers and People (SANDRP), one of the signatories to the appeal.

A Supreme Court-appointed committee looking into the 2013 floods in Uttarakhand's Kedarnath area, which is believed to have killed 5,000 people, had asked for proper environmental studies on hydropower development in this "disaster-prone" region. It argued that these dams significantly amplify the damage caused by natural disasters.

India has 4,407 large dams, the third highest number in the world after China (23,841) and the USA (9,263), with an installed hydro-electricity capacity of 46 gigawatt, which would suffice to provide nearly twice the daily peak power demand of Maharashtra. Most of this (112 gigawatt or 78%) is concentrated in the northern Himalayan states. Further, 38 large hydropower projects are under construction as of November 2020.

India has set an ambition of installing 450 gigawatt renewable energy capacity by 2030, so far it has installed 146 gigawatt which includes large hydro (31%) , solar and wind capacity (69%).

Hydropower not a green alternative

How do hydropower dams become sources of methane emissions? According to studies, decaying vegetation beneath the reservoirs generates emissions. Also, rivers flowing into reservoirs deliver not only significant amounts of organic matter and sediment from upstream, but also nutrients like nitrogen and phosphorus from agricultural activities, fertilisers and human waste, driving algae growth and providing more material for microbes to break down and convert to methane. Research also shows that reservoirs experience more fluctuation in water levels than natural lakes, and a fall increases the amount of methane released into the atmosphere.

India's push for hydropower projects as an environment-friendly option is thus misguided, said Shripad Dharmadhikari, analyst at the research organisation Manthan Adhyayan Kendra. "But unlike coal where emissions are proportional to capacity of the thermal plant, in hydropower dams, the methane emission differs between plants. In the Himalayas, one suspects that emissions would be high because a lot of environmental degradation has taken place because of dams."

In a Lok Sabha reply in March 2021, the Minister of New and Renewable Energy R. K. Singh claimed that one of the measures the government took to transition away from coal to clean energy was by declaring hydropower dams as renewable energy sources.

"In 2000, the World Commission on Dams, a global multi-stakeholder body established by the World Bank, was the first to investigate the effectiveness and performance of large dams around the world," said Thakkar. "The body concluded that dams are not environmentally friendly and there are enormous financial, environmental and human costs associated with them."

While methane emissions are second to carbon dioxide in contributing to global warming, its warming effect is 28-34 times that of carbon-dioxide, we reported in August 2021. Further, GHG emissions from reservoirs are 29% higher than previously estimated, and "much of the increase in emissions comes from previously unaccounted for methane degassing, a process where methane passes through a dam and bubbles up downstream", according to an analysis by scientists at Washington State University, US, and University of Quebec at Montreal, Canada.

Socio-economic impacts

During the Chamoli disaster in Uttarakhand in February 2021, large glacier chunks had fallen 1,800 metres from the Ronti Peak in the upper Himalayas and cascaded down the mountain. This had then mixed with rock and sediment, resulting in a massive debris flow that destroyed roads, bridges and hydropower dams. Nearly 200 people lost their lives in this disaster.

"Our understanding of what is 'clean' comes from a very limited and narrow notion that dams don't emit smoke," said Dharmadhikari of Manthan Adhyayan Kendra. "But large dams have caused much larger social and ecological damage like deforestation, loss of biodiversity and displacement of communities that are often neglected."

In India, a slew of run-of-the-river (ROR) hydropower projects--which, unlike conventional dams, do not have large reservoirs and thus exert less strain on the immediate environment--were built from 2000 onwards. These were driven by subsidies for the private sector available through the UN Clean Development Mechanism (CDM) under the Kyoto Protocol, an international treaty that commits states to reduce greenhouse gases, said Manshi Asher, a researcher at the Himdhara Environment Research and Action Collective.

"Most hydropower plants in the Himalayan region fall in climatically vulnerable and ecologically fragile regions of Kinnaur, Chamba or Lahaul-Spiti. These run-of-the-river dam projects involve large-scale construction on both the surface as well as underground, with drilling machines [being used] on an already vulnerable terrain," Asher said. "This has escaped environmental scrutiny at multiple levels."

Large dams have also failed to rehabilitate communities they displaced. The Pong dam, one of the several large dams built in India in the 1970s; the Hirakud dam, independent India's first large dam project; and the Sardar Sarovar dam on the Narmada River are all projects where the rehabilitation of those displaced remains incomplete, we reported in December 2020.

Several projects have also been aborted or delayed because they are entangled in land conflicts, forest and environmental clearance issues, rehabilitation and resettlement issues, geological uncertainties, funds constraint, and so on, as per the Standing Committee report on energy submitted in Lok Sabha in August 2021. The committee further noted that the time overrun in 24 hydropower projects currently under construction ranges from 12 to 189 months and cost overruns up to 473%.

"The Indian private sector has refrained from building hydropower plants because it is economically non-viable given the large investments. But public sector units have been stepping in to carry on these projects," said Thakkar. In September 2021, the public sector company NHPC Limited offered to take over four hydropower projects of 6,000 MW (6 GW) capacity from private companies.

'Cheaper, greener options available'

The main purpose of hydropower dams was to balance the grid because of the intermittency of renewable energy supply. "A lot of existing hydropower dams are not performing that function. They are running all the time rather than on peak load to balance the grid," said Dharmadhikar of Manthan Adhyayan Kendra. "With cheaper, more reliable and more environmentally benign alternatives such as hydrogen storage and battery storage systems available, we won't even require dams anymore."

In October, the power ministry invited suggestions for creating a comprehensive policy on energy storage that would "absorb the large-scale integration of the renewable energy into the system during the coming years". Renewable energy is intermittent, and can cause the grid to trip, so backup power is needed and stored hydropower is being promoted as a potential solution.

India's 1,115 ageing dams, over 50 years old by 2025, are becoming more expensive to maintain, and less functional due to sedimentation. India must conduct a cost-benefit analysis of these dams, and conduct timely reviews of their operational and ecologicalical safety, as well as the safety of those living downstream, we reported in February 2021.

We sought comments from the Ministry of Power on why large hydropower dams were declared as renewable energy projects given their socio-economic and environmental costs. We will update when we receive a response.

We welcome feedback. Please write to We reserve the right to edit responses for language and grammar.

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