Why flooding raises alarm over bearing of hydropower plants on the Himalayas

The need of the hour is to put halt large hydel-power projects in the Himalayas. Can small hydropower plants offer a sustainable solution?

By Jasleen Bhatti
Published: Thursday 29 July 2021

Hydropower is a renewable and non-polluting source of energy. India has an economically exploitable and viable hydropower potential, which is estimated to be about 84,000 megawatt at 60 per cent load factor. It has an installed capacity of 148,701 MW, according to the National Hydroelectric Power Corp. 

The Central Electricity Authority reported that the country has around 13,000 MW of hydropower plants under construction, with another 8,000 MW slated to start in the next six to eight months. Currently, the installed capacity of hydropower in the country is 45,700 MW.

Small hydel power projects up to 25 MW in India are under the Union Ministry of New and Renewable Energy (MNRE) and large hydel-power projects exceeding 25 MW are under the Union Ministry of Power. The country has set a target of 175 GW of renewable power capacity by 2022, including 5 GW of small hydropower. 

India's hydropower capacity is expected to reach 70 GW by 2030, according to MNRE.

The power ministry in its draft amendment of the Electricity Act has proposed to include hydropower within the renewable purchase obligation targets set for the state power distribution companies.

In India, the western Himalayan states of Jammu & Kashmir, Uttarakhand, and Himachal Pradesh are rich in hydropower potential as they have numerous glaciers and rivers. Hydropower generation in these states increases in summers but decreases in winter (from December to March) because of the freezing of glaciers and lakes.

As water stored in a reservoir falls on a turbine, its kinetic energy is converted to mechanical energy. In turn, the generator converts the mechanical energy of the turbine into electricity.

A hydroelectric plant's turbine is custom-made for maximum efficiency. The generated electricity is then transferred to the communities by way of transmission lines, and the used water is returned to lakes, streams and rivers.

No takers for surplus power

In Himachal Pradesh, the generation in some 70 state-owned large hydropower projects is between 50-55 million units per day. Despite scanty monsoon rains, the daily generation is optimum due to the sufficient flow of water in rivers owing to the melting of glaciers.

However, the state’s demand is 300 lakh units a day, while the rest is supplied to Punjab, Delhi, Goa, among others, according to their demand. The daily per unit rate to these states varies from Rs 2.50 to Rs 5, which is quite low.

The cash-starved distribution companies in these states, which were earlier procuring electricity in bulk, are opting for power cuts.

Why are large hydel power projects in the Himalayas a cause of concern?

There has been an increase in extreme weather events in the Himalayan states. During the Chamoli disaster in Uttarakhand in February 2021, 27 million cubic meters of rock and ice fell 1,800 meters from Ronti Peak in the northern Indian Himalayas.

Ice from the glacier melted as it cascaded down the mountain; it got mixed with rock and sediment, resulting in a powerful debris flow that destroyed roads, bridges and hydroelectric plants. More than 200 people lost their lives; most of them were construction workers at the Tapovan hydroelectric plant. Large hydropower plants have raised concerns about their environmental impact.  

In Himachal Pradesh, torrential rains caused massive flooding on July 11, 2021. Within 30 hours, Dharamshala received 300 millimetres of rain. Palampur in Kangra district recorded 155 mm of rain the same day. 

The torrential downpour in the region caused a flood-like situation, with parked cars being washed away and houses being partially damaged. 

Scientists have said many factors contribute to flooding, but the warming of the atmosphere caused by climate change makes extreme rainfall more likely. In the last few years, increasing evidence has emerged that large hydropower projects may not be as clean and green as claimed.

Increasing hydel power development in the Himalayas has drastically altered fragile ecosystems. By releasing minimal water downstream, large hydroelectric projects have disrupted fish migration, leading to a loss of aquatic biota and diversity.

A series of dams constructed on a river has fragmented its length, which affects riverine biodiversity. Water quality has been impacted by the loss of free-flowing water.

National Environmental Engineering Research Institute (NEERI) research has highlighted the detrimental effects of the Tehri dam on the unique capacity of Ganga Jal in the Bhagirathi to purify itself.

Large storage-based hydro projects also result in the submerging of villages and the displacement of people. Furthermore, they alter the volume of water flow downstream, which affects irrigation.

Underground civil work components in large hydropower projects are quite extensive; they involve blasting and dynamiting and enhance existing vulnerabilities as well as unleash effects not thoroughly studied and understood.

The Geological Survey of India reported that 97.42 per cent of the area of Himachal is prone to landslide hazards. A study published by the Himachal government's Disaster Management Cell found that a large number of hydropower stations face landslide hazards.

One in four hydropower projects in the Himalayas is at risk from landslides caused by earthquakes and tremors, according to a study released last year by the Institute of Earth and Environmental Science in Germany,.

In India, to mitigate the loss of forest lands diverted for hydropower projects, compensatory afforestation policies have been implemented, which have resulted in more physical interference with natural landscapes whose long-term consequences remain unclear.

Does small hydropower equate to low impact hydropower?

The Union government should halt large hydropower projects in the Himalayas and promote only small hydropower (SHP). These projects are governed by state policies, and the potential sites are allocated by state governments. 

SHPs are canal-based or run of river types that use running water to drive the turbine. In general, SHPs do not encounter the problems associated with large hydel projects, which include construction of dams, deforestation, and relocation.

Remote and isolated areas can benefit from these projects. These plants have a long useful life and their generation costs are almost inflation-free. In addition to conserving fossil fuels, the plants reduce carbon emissions because they substitute thermal power.

As a result, SHP is one of the most attractive renewable sources of grid-quality electricity. They are ideal for powering villages and far-flung or isolated areas. The accessibility of electricity in these areas will boost small-scale industries and thereby improve the socio-economic status of the residents.

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.