Purulia pumped storage project shows why pumped hydropower may not be clean

Banner image: The PPSP dams located amidst densely forested hills. Photo by Aniket Bhattacharya.
  • The Purulia Pumped Storage Project (PPSP) in West Bengal is among six operational pumped hydro projects in India. The government claims the project to be success story in clean energy generation and wants to establish three more such projects in the state.
  • But locals claim the project ravaged dense forests, engulfed elephant habitat and impacted the livelihoods of those dependent on forests.
  • Experts question the need for such projects without effective peak management of existing hydropower capacity.

As a young boy growing up in Saharjhuri village located in the Ajodhya hills in West Bengal’s Purulia district, Suresh Kisku (name changed on request) did not dare venture into the forest located barely 2-3 kilometres from his home.

“The jungle was very dense and wild elephants often camped there for days, arriving from the Dalma hills …” recalled Kisku, now in his early 30s and a primary school teacher in Kolkata who was visiting his family in the village, when Mongabay-India met him.

The densely forested Ajodhya hills are part of the Dalma elephant corridor, through which hundreds of elephants migrate to West Bengal from the neighbouring state of Jharkhand in August-September every year. The hills also host other endangered species such as pangolin, wolf and leopard.

In the early 2000s, the state government established the Purulia Pumped Storage Project (PPSP) in the Ajodhya hills, comprising two dams. It was the first of four such projects planned in the hills and its primary objective was addressing peak time power requirements in the state. The government claims that the PPSP is a “success story” in clean energy generation and seems keen to push through three similar projects in the hills, each comprising two dams.

But local people such as Kisku said the PPSP engulfed prime forests and affected elephant movement and feared more such projects would spell disaster for the environment and communities involved.

“When they constructed the dams, they just shaved off the forest from one side. The elephants don’t come this side much now because their path is obstructed by the dams,” Kisku told Mongabay-India, standing a few hundred metres away from the upper dam and pointing at the dense forest beyond the reservoir. “The forest here is the only major source of oxygen for 2-3 districts. If they build more dams here, the forest and environment will be ravaged.”

Similar concerns have been raised by the Paribesh Bachao Adibasi Bachao Mancha – a joint platform of environmentalists, traditional tribal organisations and civil society groups in the Ajodhya hills spearheading the resistance against similar projects.

Mongabay-India analysed key claims regarding the PPSP, spoke to stakeholders and reviewed research papers and reports about the project. The analysis shows that while it claims to be a clean energy project, it devastated hundreds of hectares of dense forests and obstructed rivulets and subterranean streams such that its environmental costs far outweighed its purported benefits.

Currently, six pumped storage projects including the PPSP are operational in India and many more are in different stages of development. These projects differ from conventional hydropower projects in two ways – they comprise not one but two dams and their primary objective is not power generation but stabilisation of power in the grid.

The water inlets in the upper dam of the PPSP. Photo by Aritra Bhattacharya.
The water inlets in the upper dam of the PPSP. Photo by Aritra Bhattacharya.

Usually, in pumped hydro projects, two dams are constructed at varying altitudes and connected via an underground aqueduct. Water retained in the upper dam is released during periods of high demand to rotate turbines and generate electricity, following which it drains out into the lower dam. During periods of low demand when there is excess power in the grid, it is pumped back to the upper dam, ready for another generation cycle.

In conventional hydropower projects, the height from which water is released to rotate turbines is limited by the height of the dam. But in the case of pumped storage, this height can be increased substantially by locating the upper dam at a higher altitude. This enables pumped storage projects to generate a large amount of power within a short period to meet peaking demands.

Pumped storage is deemed climate-friendly as it does not involve any direct carbon emission, submerges a lesser area per megawatt (MW) of electricity generated compared with conventional hydropower, and can be a ‘closed loop’ as it does not need a continuous natural water supply.

Read more: [Commentary] The role of hydropower projects in development and disasters in Uttarakhand

Need for pumped storage projects in West Bengal

Since the 1980s, four pumped storage projects are planned in West Bengal, all in the densely-forested Ajodhya Hills in Purulia district. The state-owned West Bengal State Electricity Distribution Company Limited (WBSEDCL), implementing agency for these ventures, claims pumped storage projects are highly needed in West Bengal to meet peaking power demands and “flatten the demand curve” especially because more than 90 percent of the state’s installed capacity comprises thermal power.

“Pumped storage mechanism stabilises grid frequency, meets peak demand instantly and increases plant load factor, efficiency and life of thermal plants. It also reduces damage to industrial equipment,” states the WBSEDCL.

Experts concurred with the need to address peak power requirements but questioned the basis for establishing new projects comprising dams, especially in eco-sensitive areas.

“Generation in thermal power plants cannot be scaled up or down quickly owing to technical reasons. They are also susceptible to damage due to sharp fluctuations in demand resulting in grid collapse. So in theory, there is a need to ‘balance the grid’ in technical terms,” said Shripad Dharmadhikary, coordinator, Manthan Adhyayan Kendra, a research centre devoted to water and energy issues.

He said that pumped storage projects were well suited for this purpose, but issued a caveat. “Although less hazardous compared with thermal or hydropower, pumped storage projects do have an impact on the environment which is very location-specific. For instance, when projects are located in hilly, forested areas that are rich in biodiversity, their impact could be substantial owing to land submergence, construction of access roads and other activities at the project site,” he noted.

The impact of the PPSP 

The work on the PPSP, the first pumped storage project in the Ajodhya Hills as well as in West Bengal, was completed between 2002 and 2007 courtesy of Rs. 29.5 billion (Rs. 2,953 crores) loan from the Japan International Cooperation Agency (JICA). Water from the Kistobazar nala, a seasonal stream, was impounded in the upper dam, whereas the lower dam was in an off-stream area, making the project ‘closed loop’ and more environment friendly. It was commissioned in 2008 with an installed capacity of 900 megawatts (MW).

On paper, the PPSP took up around 442 hectares of land, of which 373 hectares was forest land, which often hosted herds of wild elephants for weeks according to Kisku and other villagers.

It is difficult to establish if the project’s environmental impact was considered during the planning stage, and if adequate mitigation measures were taken as publicly available official documents provide little or no information on the subject.

However, a document on JICA’s website, which funded the PPSP, claims that it was “likely to have minimal adverse impact on the natural environment because the project area is not considered an important habitat for protected species.” Whereas another document from the WBSEDCL claims that since the PPSP was a ‘closed loop’ project – wherein reservoirs were located in areas that were physically separated from existing river systems – its impact on aquatic systems was minimal.

However, these claims are contested by residents of Ajodhya Hills as they allege that wild elephant herds have attacked villages and destroyed standing crops on several occasions after the project came up while earlier they rarely used to enter the villages.

“The government undertook plantations in a few places after the PPSP was constructed, but their area was much lesser compared to the original forest. Many trees were also felled in later years to make way for resorts and hotels that came up to cater to tourists visiting the PPSP dams,” rued Nakul Baske, resident of Chhatni village and a member of the Paribesh Bachao Adibasi Bachao Mancha.

The gate to the power house at the PPSP. Photo by Aritra Bhattacharya.
The gate to the powerhouse at the PPSP. Photo by Aritra Bhattacharya.

“Earlier the Kistobazar nala (rivulet) used to flow through the hills to the Kistobazar Irrigation Project dam. But since its waters were impounded by the PPSP, we don’t get to see the nala downstream. The flow of many subterranean streams is also likely to have been affected,” said Sourav Prakritibadi, an environmental activist and a member of the Mancha.

In 2010, two years after PPSP was commissioned, professors Abhishek Chakrabarty and Soumendu Chatterjee published a research paper in the Indian Journal of Geography and Environment examining its impact on the environment. Their study found that between 2000 and 2005, when a bulk of the construction work was undertaken, forest cover in the area reduced by nearly 10 percent (from 93.8 to 85.8 square kilometres).

It revealed that nearly 3.5 million trees were felled in an eight square kilometre area, which was part of the migratory route of elephants and habited by many animals and birds such as wild pig, barking deer, hare, langur, squirrel and jungle fowl.

Further, the loss of forest cover contracted the area from which local villagers, mostly tribals, collected firewood and minor forest products such as mahua, honey, fruits, lac, yams, sal and tendu. Around 12 square kilometres of multi-crop land in downstream areas was rendered fallow, largely due to water from the Kistobazar stream being impounded in the upper dam. This affected agricultural productivity as well as fishing activities, whereas the “impoundment and recycling of river water for power generation will also disturb the Kistobazar River Ecosystem,” the study noted.

Read more: India’s tidal power potential hampered by high costs and environmental risks

Why alternatives should be explored

The WBSEDCL data on power generation by the PPSP shows that between 2013-14 and 2018-19, the project’s annual power production averaged around 1,000 MW, whereas its annual consumption averaged around 1,300 MW. Although this indicates that the PPSP is a net consumer of electricity, its performance matches pumped storage projects in other parts of the world that are known to have an efficiency of 75-80 percent.

But this claimed benefit was only a fraction of the costs associated with the project, the study by Abhishek Chakrabarty and Soumendu Chatterjee found. Their analysis showed the annual financial cost (Rs. 7,642.33 million or Rs. 764.2 crore) of the PPSP was lesser than the claimed benefit (Rs. 8,371.12 million or Rs. 837.1 crore) and it appeared to be making a profit. But when environmental and social costs were factored in, the annual cost (Rs. 58,195.8 million or Rs. 5819.5 crores) was about six times the annual benefit (Rs. 8,727.12 million or Rs. 872.7 crores).

According to experts, since the other three pumped storage projects planned in the Ajodhya Hills are located in densely forested areas, their environmental costs will likely outstrip benefits by a huge margin, as in the case of the PPSP. They said pumped storage projects were being pushed through across the country without exploring alternatives like demand management, utilisation of existing hydropower projects as peak load stations, and storage batteries.

A tea stall with posters saying no to more pumped storage projects in Ajodhya Hills. Photo by Aritra Bhattacharya.
A tea stall with posters saying no to more pumped storage projects in Ajodhya Hills. Photo by Aritra Bhattacharya.

“Electricity demand can be managed in various ways such as adopting differential tariffs for peak and non-peak periods and providing power to large industries at night when demand is low. Although such initiatives can flatten, trim or shift the demand curve in significant ways, and some states have adopted them, there’s no real effort at the national level to manage demand,” said Dharmadhikary.

Transitioning existing hydropower projects into peak load stations was another important alternative, said Himanshu Thakkar from the South Asia Network of Dams, Rivers and People.

“Anecdotal evidence suggests a bulk of hydropower projects in the country function as baseload stations, meaning they operate continuously to meet the minimum level of power demand over 24 hours. In most cases, they can easily be turned into peak load stations by aligning the volume and timing of water release with the demand curve. But this option is not being explored, barring in isolated cases,” he said.


Banner image: The PPSP dams amidst densely forested hills. Photo by Aniket Bhattacharya.

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