Status of hydropower dams in Bhutan

Tuesday, April 14, 2015

Note: This page was last updated in April 2015.


Projects Commissioned

Chukha HEP:

The Chukha HydroElectric Project (HEP) is Bhutan’s first large hydropower project, conceived in the 1970’s, and commissioned in the late 1980’s. The 336 MW undertaking is sited on the Wangchhu river (or Raidak) in Chukha district. Built by India on a turnkey basis, 60 per cent of the capital was provided as grant, the rest in the form of a concessional loan. The loan was repayable in 30 installments over a period of 15 years, with an annual interest rate of 5 per cent.

Project construction began in the mid 1970’s and took a little over a decade to be completed and commissioned, costing Rs 246 crore. The design included a 6.5 km long headrace tunnel and a 40 metre high dam. The project is a revenue earner for Bhutan through export of electricity to India. Until a decade back, Chukha HEP alone contributed for over a quarter of Bhutan’s total revenue. Druk Green Power Corporation (DGPC) operates the plant.  Initially, 90 per cent of electricity generated was exported to India. After 2005, due to increase in domestic demand, approximately 80 per cent is being exported to India.

Kurichhu HEP:

The Kurichhu HEP was the second large Bhutanese hydroelectric facility to be commissioned in 2001-02. The 60 MW project is sited on the Kurichhu River, also knows as the Lhobrak, in Mongar district. The Government of India, as in the case of Chukha HEP, provided a grant covering 60 per cent of the project cost (Rs 555 crore). The rest was provided as a loan, repayable over a period of 12 years at a simple interest rate of 10.75 per cent. A 55 metre high dam was built on the Kurichhu, which flows in a southwesterly direction and joins the Manas River, a major tributary of the Brahmaputra that drains most of eastern Bhutan. The project is operated by DGPC and during the peak generation season, exports more than 60 per cent to India. The power tariff was revised from Rs 1.80 to Rs 1.89 in 2008 and to Rs 1.98 per unit in 2011.    

Basochhu HEP

Basocchu was identified as a source of hydropower in the 1970’s. The Austrian government financed the pre feasibility study, and in the early 1990’s Austrian engineers designed the project with a 9 metre high dam, with two turbines having a total capacity of 40 MW. The project was commissioned in 2005 as the third large hydropower facility in the country. All the power generated is sold within Bhutan. Financed by the Austrian government, the project cost 1248 million Ngultrum ($1 USD = approx 62 Ngultrum). Approximately 56 per cent was provided as a loan, the rest as grant. The Royal Government of Bhutan spent an additional 192 million Ngultrum to cover project costs. The loan repayment began in December 2006, and will be paid quarterly for 20 years. 

Dagachhu HEP

In February 2015, one of two turbines at the 126 MW Dagachhu HEP was commissioned. The second turbine was operationalized the following month. This is the first project to be managed by Bhutan, operated by DGPC. The facility is a joint venture between DGPC, Tata Power and National Pension & Provident Fund of Bhutan. Tata Power, an Indian company, will import the power on the basis of a 25-year power purchase agreement, to sell electricity in the Indian market.

The HEP, located in southwest Bhutan, is being developed on the Dagachhu River, more than 10 kilometers upstream of its confluence with the Punatsangchhu. The Asian Development Bank has provided a loan of $51 million, which is around a fifth of the total project cost.

Tala HEP:

After commissioning the Chukha HEP, a proposal for another hydropower plant in the Wangchhu river basin was conceived in the 1980’s. It was much later, in 1996, after preparing a pre-feasibility report, followed by field investigations and studies, that an agreement for the implementation of the Tala HEP was signed between India and Bhutan for the construction, and Operation & Maintenance of the project.

With six turbines, Tala HEP was commissioned in 2006-07 as a 1,020 MW project, downstream of Chukha HEP. Tala HEP was funded at a total cost of Rs 4,125 crore by the Government of India with 60 per cent as grant and 40 per cent in the form of a loan.

Tala HEP is Bhutan’s biggest hydropower project currently operating, followed by the 336 MW Chukha project (commissioned in 1988), the 126 MW Dagachhu HEP (commissioned in 2015), 60 MW Kurichhu HEP (commissioned in 2001) and 40 MW Basochhu HEP (commissioned in 2005). The project comprises a 92-metre high concrete dam, and 23 km long headrace tunnel.

The tariff for export of power to India has been fixed at Rs 1.80 per kWh in line with the Power Purchase Agreement. Surplus power is exported to India; the Tala HEP is required to meet domestic energy requirements.


Projects under construction

Punatsangchhu-I HEP

Less than 100 km east of Bhutan’s capital, a 1,200 MW hydroelectric project is currently under construction on the Punatsangchhu River. Funded by the Government of India with 40 per cent grant, the rest as loan, the eponymously named Punatsangchhu-I project entails a 130 metre high concrete dam, with two diversion tunnels and a headrace tunnel 10 km in length. It is expected that the project will be commissioned in the last quarter of 2018.

The loan amount exceeding Rs 2,000 crore is repayable in 12 annual installments, one year after the date of operation at an annual interest rate of 10 per cent. The total cost of the undertaking is Rs 3,515 crore. Latest reports state that the project cost escalated from $554 million in 2006, to $1.74 billion. In 2013, the right bank gave way, due to geological instability. 

Water and Power Consultancy Services (WAPCOS) of India prepared the detailed project report, while the civil and electro-mechanical works were awarded to Hindustan Construction Company, Bharat Heavy Electrical Ltd., Larsen & Toubro and Gammon (India) Ltd.

As per information, the dam site was originally a few kilometers downstream of the current dam site. The dam site was shifted upstream so that more power could be generated. In 2013 there was a massive landslide on the right bank of the dam axis. This has resulted in substantial increase in cost of the project and delay in its commissioning. Till November 2014 the work on stabilization of the hill was in progress.

Punatsangchhu-II HEP

Located 3 km downstream of the Punatsangchhu-I power house is a 86 metre high concrete dam with a headrace tunnel of 8.6 km. Named Punatsangchhu-II, the HEP was revised from 990 MW to 1020 MW and will cost Rs 3,777 crore. The Government of India is funding the project with a 30 per cent grant, as well as a loan that is repayable in 30 bi-annual installments at 10 per cent annual interest, commencing one year after the date of operationalization.

Former Prime Ministers of India and Bhutan, Manmohan Singh and Jigme Thinley laid the foundation stone for the project. Construction of the project commenced in 2010, and is running behind its 7-year completion schedule. As with the Punatsangchhu-I HEP upstream, the venture could be completed by the last quarter of 2018. The geology of the left bank however nearly gave way in February 2015, but the project proponents have managed to control the situation. It has however led to some time delays.    

WAPCOS Ltd. (a Government of India Undertaking) are the engineering design Consultants, while Jaiprakash Associated Ltd were awarded the contract for main civil works including the dam and diversion tunnel.

Mangdechhu HEP

The Mangdecchu HEP is a 720 MW project currently under construction in Trongsa district in Central Bhutan. Along with the two projects on the Punatsangchhu River, this is the third large hydropower project that is nearing completion in Bhutan. Construction of the project commenced in 2009. It was initially hoped that construction would be completed by 2016, but is behind schedule. Like the second string of projects funded by the Government of India, the grant component is less than the loan amount; 30 per cent is a grant, which together with the remaining loan, amounts to Rs 2,896 crore.

The project, also named eponymously on the river it is situated on, entails a 56 metre high concrete dam and 13.5 km headrace tunnel. National Hydro Power Corporation (NHPC) of India prepared the detailed project report, while the main civil and electro-mechanical works were awarded to Jaypee, Bharat Electricals Ltd and Gammon (India) Ltd.

In August, 2015, the project suffered a significant landslide, burying five workers at the site. Reportedly the landslide occurred when the wall of the construction pit for the dam collapsed. 

Kholongchu HEP

In June 2014, Prime Minister of India laid the foundation stone of the 600 MW Kholongchu HEP, initially conceived as a 486 MW project. Satluj Jal Vidyut Nigam Ltd (SJVNL) prepared the detailed project report, a central public sector undertaking of the Government of India, which was then approved by India’s Central Electricity Authority in November 2012. In May 2013, the Royal Government of Bhutan white flagged the report. The venture to be jointly developed by SJVNL and DGPC will entail a 95 metre dam with a headrace tunnel of 15.77 km that will expectantly generate enough head to run four 150 MW turbines. The Project shall be financed on 70:30 debt to equity ratio. Total cost of the project is Rs 4,076.67 crore at July 2013 price level. Environment clearance for the project was obtained from the National Environment Council of Bhutan in July 2014. Construction work began in the last quarter of 2014, but has been slow from the get go. Controlled blasting commenced in September 2015, and pre-construction activities it is stated will take 18 months, before tendering work for the dam, surge shaft and powerhouse. 

Wangchhu HEP

The preliminary construction work on the 570 MW Wangchhu HEP has begun. It was originally conceived as a 900 MW project. The detailed project report was vetted by the Central Electricity Authority of India in March 2014 and submitted to the Royal Government of Bhutan in May. The project entails a 134 metre high concrete dam, with a 12.38 km long headrace tunnel, which will expectantly generate head to drive four turbines of 142.5 MW each. It is expected that the project, sited on the river Wangchhu, will annually generate 1968.55 million units of energy.

The Wangchhu HEP is one of four projects totaling 2,120 MW as part of an India-Bhutan agreement signed to jointly promote hydropower development in April 2014. The Government of India will finance the project at an estimated cost of Rs 3,868.67 crore (June 2013 price level). Majority of funds will be made available in the form of a loan, whereas 30 per cent will be provided as a grant. The project is a joint venture by SJVNL and DGPC.  

Nikachhu HEP

The feasibility study for the 118 MW Nikachhu hydropower project was prepared in 2012, while the environmental clearance was received in July 2014. The project, along with others, has helped build the capacity of Bhutanese agencies such as DGPC, which now has the relevant capacity to conduct pre-feasibility studies in-house. The proposed project with 33-metre high concrete dam is located more than 150 kilometers from the capital, and around 3 kilometers downstream of the confluence of the Nikachhu and Chhunabachhu in Trongsa district. Much of the power will be exported to India in the summer, while it will also help fulfilling the power corporations mandate of achieving energy security in the country.

The news is that India’s Power Trading Corporation will purchase all electricity that is generated and the Government of West Bengal has signed a Memorandum of Understanding with PTC to purchase all electricity generated by this project.

The so-called run-of-river project will discharge the channeled water through the tailrace tunnel, 2 meters above the Full Reservoir Level of the Mangdechhu HEP. Reports suggest that this area is largely uninhabited. The Asia Development Bank will fund approximately $120 million, which is 60 per cent of the project cost. Of the ADB funding, $25 million is a grant, the rest in the form of a loan.


Proposed Projects

Bunakha HEP

The Bunakha HEP is named due to the project sites proximity to village Bunakha in Chukha Dzong. The site is little more than 3 km upstream of the commissioned Chukha on the Raidak River. The detailed project report for the 180 MW HEP was prepared by THDC India Ltd, a joint venture of Government of India and the state government of Uttar Pradesh. The report was approved by India’s Central Electricity Authority in August 2013 and will be developed by Tehri Hydropower Development Corporation and DGPC   

Amochhu HEP

Amochhu HEP is sited upstream of the point where the Amochhu river enters the northern part of West Bengal in India. Planned as a reservoir dam project with hydropower capacity of 540 MW, reduced from 620 MW, the detailed project report of the Amochhu HEP was prepared by National Thermal Power Corporation, India’s largest energy conglomerate, and approved by the Central Electricity Authority in January 2013. It was hoped that the project construction would begin in 2013 itself, but the Government of India has expressed concerns that have held the project up. Media reports allude to security fears given that the dam is situated in close proximity to both the China and India border.

“Although still unclear when the 540MW Amochhu hydropower project will commence, the project is still valid and has not been chalked out of the government’s plan,” states the DGPC website. The economic affairs minister has declared on the floor of the National Assembly that the project is important for both countries. Given that it is a reservoir project with water storage, unlike most hydropower projects in Bhutan, it will assist in generating electricity in the months when the river water flows are low. It is probable that India is also worried about the downstream impacts of such a storage project, just upstream of its borders.

Chamkharchhu-I HEP

It is proposed that National Hydro Power Corporation of India and DGPC will jointly develop the 670 MW Chamkharchhu-I HEP. The Central Electricity Authority of India approved the detailed project report in last year.

The project necessitates a 108 metre high concrete dam. The powerhouse located on the right bank of the river Chamkharchhu, is approximately 3.5 km upstream of its confluence with the river Mangdechhu. The Mangdechhu joins the Manas River, which drains into the Brahmaputra.  

As per information available, this project has now been modified and renamed as Chamkarchhu Integrated and will have two dams. One will generate 1,397 MW and the other will generate 857 MW, making a total of 2,250 MW.

An online petition to have one of Bhutan’s major rivers, the Chamkharchu, without a dam has sparked a debate on the social, environmental and economic impact of dams. Yeshey Dorji, the petitioner, says local communities are unlikely to reap any significant economic benefits. But in Septmeber 2015, the Prime Minister of Bhutan turned down the petition saying that the petition has come at too late a stage in project development, and that it is in the benefit of the country as well as the local communities that the hydropower project is completed. 

Sankosh HEP

The Sankosh project is part of the ultimate goal of developing 10,000 MW of hydropower in Bhutan by 2020. Initially constituting 40 per cent of this target, the project was downsized from 4,060 MW to 2,560 MW by a joint group comprising officials representing both governments. The dam height was reduced from 265 meters, eventually to 215 meters, which significantly reduced the project cost to make it more attractive financially per MW capacity. 

The original detailed project report was prepared in 1995, but due to delays the report was updated and revised in April 2009, with the aforementioned changes. The feasibility report was reviewed in 2012, while construction was readied for mid-2013. But even after improving the financial viability of the project, the Government of India has been reluctant to make the funds available for this project. 

Kuri Gongri HEP

The pre feasibility report for the 2,640 MW Kuri Gongri project was prepared in July 2012. Initially conceived as a 1,800 MW project, it was revised to 2,640 MW. Of all the alternatives considered, the National Hydro Power Corporation of India considered the above-mentioned capacity with a 250-metre high storage dam as the most economic alternative per MW capacity.

With the downsizing of the Sankosh HEP, the Kuri Gongri HEP became the largest potential contributor to Bhutan’s (India assisted) 10,000 MW target by 2020. WAPCOS Ltd was contracted to carry out preliminary surveys and prepare the detailed project report. The dam site was proposed in a deep gorge near the confluence of the Manas, Kuri and Gongri rivers. However, this along with the Amochhu and Sankosh HEP has been stalled due to India’s disinclination to fund the projects. Interestingly, all three schemes are reservoir based storage projects, which will have a significant impact on the quantity, quality, velocity and timing of river water, sediment and biota flow downstream in to India. Despite news of India’s unwillingness to fund this dam, as of November 2014 the Detailed Project Report was under preparation.