New Delhi: Finally, some good news from the neighbourhood! The first two turbines of the India-funded 1,020 MW Punatsangchhu-II hydroelectric project in Bhutan have started operating.
According to a report on the Kuensel news website on Friday, the first two of the six turbines started operating on Thursday. In what is a happy coincidence, this happened on the day India was celebrating its Independence Day.
"This signals the commissioning of one of the most eagerly anticipated mega hydropower projects in the country," the Kuensel report stated. "The next phase will involve integrating these turbines with the electrical and communication systems, leading to full-scale energy production."
Attending the ceremony, Bhutan’s Energy and Natural Resources Minister Gyem Tshering, described the event as "a landmark moment that marks the beginning of a new chapter in the shared journey of Bhutan and India towards completing this project".
"This achievement is a powerful reminder of what can be accomplished through cooperation and shared vision," the report quoted Tshering as saying. "It stands as a testament to our commitment to sustainable development, energy security, and the enduring friendship between our nations."
The Punatsangchhu II is a run-of-the-river hydroelectric power generating facility in the Wangdue Phodrang district of Bhutan. The project is being developed by the Punatsangchhu II Hydroelectric Project Authority (PHPA II) under an inter-government agreement between the Government of India and the Royal Government of Bhutan.
According to the PHPA-II website, the project was sanctioned at a cost of Rs 37,778 million (base cost excluding interest during construction and March 2009 price level) with an installed capacity of 990 MW (later revised to 1,020 MW). It is completely funded by the Government of India - 30 per cent in the form of a grant and 70 per cent as a loan component at 10 per cent annual interest.
India’s Water and Power Consultancy Services (WAPCOS) provided engineering and design consultancy services during the project study phase, while the National Institute of Rock Mechanics (NIRM) was engaged for modelling and geotechnical engineering services.
Construction of the project started in December 2010 with an ambitious completion schedule of seven years, including two years of infrastructure development. However, that deadline could not be met and a second deadline of end of 2022 was set. However, the second deadline too was missed and the final deadline for commissioning of the project has now been set for October 2024. The delays in meeting the deadlines were caused by a variety of reasons, including geographical challenges, flash floods, the COVID-19 pandemic and the finding of a significant shear zone at the dam foundation.
The Kuensel report cited the Chief Engineer of the Department of Energy, Ugyen, as describing the event as "historic" since a Francis turbine for a mega project is being used for the first time in the country. All other hydropower plants currently in operation in the Himalayan kingdom use Pelton turbines.
The project is located on the right bank of the Punatsangchhu River along the Wangdue-Tsirang highway between 20 km and 35 km downstream of Wangdue Bridge. The dam site is about 94 km from Thimphu along the highway. Paro, the nearest airport is about 125 km away. The nearest railway station is at Hasimara on the Siliguri-Alipurduar Broad Gauge line of India’s Northeast Frontier Railway. The project area is also accessible from Bagdogra Airport near Siliguri in West Bengal and via Phuentsholing-Semtokha (near Thimphu)–Dochula (about 440 km). The project area can also be approached from the proposed Gelephu smart city near the south-central border of Bhutan.
The Punatsangchhu River originates at the confluence of the rivers Phochhu and Mochhu at an altitude of about 1,200 metres above sea level at Punakha. The Punatsangchhu River then flows southerly to enter the Indian plains of West Bengal and eventually flows into the Brahmaputra.
The diversion dam of the run-of-the-river Punatsangchhu-II hydroelectric project is located about 20 km downstream of Wangduephodrang bridge. All other project components are situated on the right bank. Its underground powerhouse is 15 km downstream of the dam at Kamechu, Dagar Gewog (an administrative unit under a district in Bhutan).
The Punatsangchhu II hydroelectric project encompasses the construction of a concrete gravity dam measuring 91 m in height and 223.8 m in length. Additionally, it includes the establishment of an 877.46 m-long diversion tunnel with a diameter of 12 m, capable of discharging 1118 cubic metres of water per second.
The project also incorporates the construction of an upper cofferdam, measuring 168.75 m in length and 22 m in height, as well as a downstream cofferdam with dimensions of 102.02 m in length and 13.5 m in height. The primary dam will be equipped with seven sluice gates, each measuring 8 m in width and 13.20 m in height.
The power plant will have an underground powerhouse measuring 240.7 m in length, 23 m in width and 51 m in height. The six turbines are of 170 MW each.
In August last year, Ramesh Kumar Chandel, managing director of PHPA-II, had said that of the six turbines, two would be ready for commissioning by October 2024. The rest four would be commissioned by the end of this year.
According to Chief Engineer Ugyen, as testing and commissioning of the initial turbines begin, the remaining units are scheduled to come online in the coming months. He said that they don't have to wait for all six units to spin.
"These two units will now undergo some tests, and once done, it will feed electricity into the grid in the coming days,” he was quoted as saying.
Hydropower cooperation with is a key pillar of bilateral economic cooperation between India and Bhutan. For Bhutan, hydropower development continues to be a vital catalyst for socio-economic development. Revenues from hydropower constitute a significant portion of the total revenues of the Royal Government of Bhutan.
The ongoing cooperation between India and Bhutan in the hydro-power sector is covered under the 2006 bilateral agreement for cooperation and its Protocol signed in 2009. Four hydro-electric projects (HEPs) totalling 2136 MW are already operational in Bhutan and are supplying electricity to India. The 720 MW Mangdechhu was commissioned in August 2019 and handed over to Bhutan in December 2022. Apart from Punatsangchhu-II, the 1200 MW Punatsangchhu-I project is also under implementation.
India's imports of electricity from Bhutan amounted to Rs 2,448 crore in 2022, according to the Government of Bhutan’s data.
