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Hydropower as an Energy Source: Need to Find the Right Balance

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  • May 12, 2017

    While addressing the ‘World Conference on Environment-2017’, held in New Delhi on March 25-26, Minister of State for Power, Coal, New & Renewable Energy and Mines, Piyush Goyal, reiterated India’s commitment to the Paris Climate Change Agreement and stated that the country will have 225 Gigawatts (GW) of renewable and clean energy sources by 2022.1 Shortly thereafter, in reply to a question raised in Parliament regarding hydroelectric projects in the country, he stated that 16 of the 43 hydropower projects currently under construction are stalled for various reasons.2 While appraising the manner in which the hydropower projects have been undertaken in the country, the Comptroller and Auditor General (CAG) of India, in its report tabled in March 2017, found that the standard procedures including for environmental impact assessments and public hearings have been bypassed.3

    Tapping hydropower is considered a key priority area in view of India’s growing energy requirement.4 It is noteworthy that India became a net exporter of electricity for the first time between April 2016 and February 2017, exporting around 5,585 million units to Nepal, Bangladesh and Myanmar.5 However, every stakeholder needs to contemplate the impact that hydropower dams would have on the environment, and also the potential impact of climate change on dams, both before and after their construction.

    Greenhouse Gas (GHG) Emission from Reservoirs

    According to the World Energy Council, “Hydropower is the leading renewable source for electricity generation globally, supplying 71% of all renewable electricity. Reaching 1,064 GW of installed capacity in 2016, it generated 16.4% of the world’s electricity from all sources.”6 China tops the world’s hydropower capacity with 319 GW, followed by the United States with 102 GW. India stands fourth with 52 GW.7 Several countries, in order to mitigate climate change, have turned to exploring hydropower sources. Though hydropower is a clean source of energy, yet it can have a serious negative impact on the climate.

    Although studies on the status of greenhouse gas (GHG) emission from reservoirs is ongoing, an earlier study by Brazil’s National Institute for Space Research (INPE) discovered that significant amounts of carbon dioxide, nitrous oxide and methane are emitted from reservoirs, turbines and spillways, and that methane alone accounts for 104 million metric tonnes of all these emissions annually.8 Mostly, methane is generated by the decomposition of vegetation and soil submerged by the reservoirs. A research paper by Philip Fearnide also found that hydropower dams located in tropical regions generate more methane than those located in temperate zones.9 Another extensive study led by Bridget R. Deemer, on GHG emission from 267 large reservoirs around the world, ascertained that although methane in the atmosphere stays for only a short while compared to carbon dioxide, more than 80 per cent of methane emissions come from water storage reservoirs created by dams, contributing almost three times more to global warming compared to carbon dioxide.10 Although the findings of hydropower’s contribution to GHG emissions remain consistent, none of these emissions are included in global greenhouse inventories. 

    Climate Change and Vulnerability of Hydropower

    The second point of concern is the impact of climate change, where it is likely to alter river discharge, which in turn impacts the availability of water resources, water regularity and hydropower generation. Water is constantly replenished by a process of hydrological cycle in the atmosphere, but this cycle could get altered due to climate change. Floods, droughts, changes in temperature, precipitation and melting glaciers are all symptoms of climate change. Since the amount of electricity a hydropower plant can produce directly depends on the availability of water resources, lower the river discharge, lesser the power generation. In a preliminary study on the impact of climate change on dam facilities, Ben Blackshear et. al. have sketched out the different types of dams across the world – pumped storage, reservoir and run-of-the-river – and the factors that are likely to affect their generation of electricity.11

    Major rivers like the Indus, Ganga and Brahmaputra are fed by snow and glacier melt. But the retreat of glaciers in the Himalayas is likely to alter the pattern of river flow, resulting in the disruption of hydropower production. A one per cent reduction in the flow can reduce electricity output by roughly three per cent.12 Moreover, one cannot ignore the economic risks of investing in a hydropower project under the prevailing conditions of climate change. Bhutan, which boasts of a hydropower potential of around 30,000 MW, has invested enormous capital in the same in recent years, but is likely to face an economic risk on the returns in the years to come, apart from environmental risks.13 The social impact of large dams by way of population displacement and loss of income from farming and livestock should also not be overlooked.

    In order to reduce the impact of climate change, governments have agreed under the Paris Climate Change Agreement to cut “the global average temperature to well below 2 C above pre-industrial levels.”14 But developing renewable energy, as seen earlier, also comes with attendant risks. Minister of State Goyal had rightly observed that “it is time that human beings understand that climate change is a challenge caused by humans, and ultimately it is humans who can address it.”15 While hydropower projects are critical for economic growth and development, it is equally important to fully assess its potential social and environmental impact in the long-term. The challenge lies in finding the right balance between the need for rapid development and the necessity of protecting the environment

    Views expressed are of the author and do not necessarily reflect the views of the IDSA or of the Government of India.