The 3GW Nurek hydropower plant in Tajikistan, the biggest hydroelectric power facility in Central Asia, is undergoing a major rehabilitation programme to boost its generating capacity.
The power station comprises nine generating units commissioned between 1972 and 1979. After more than 50 years in service, the facility is presently operating at 77% of its design capacity due to ageing equipment and lack of maintenance.
Owned and operated by the state-run electric utility Barqi Tojik, Nurek is a strategically important power station that accounts for more than 70% of Tajikistan’s total power generation.
The phase one rehabilitation project for the facility, which is estimated to cost approximately £285m ($350m), was initiated in March 2019 and is expected to continue through 2023.
It will be followed by phase two refurbishment and modernisation works that are also estimated to cost another £285m ($350m). The phase two rehabilitation project is scheduled for completion in 2028.
The Nurek hydropower station is located on the Vakhsh River approximately 70km south-east of Dushanbe, the capital city of Tajikistan.
The run-of-the-river hydroelectric plant is located in central Tajikistan, approximately 70km downstream of the Rogun hydropower project being developed on the Vakhsh River.
Nurek dam and reservoir details
The Nurek hydropower facility comprises of a 300m-tall earth-fill embankment dam that creates a 98km2 reservoir with a total storage volume of approximately 10.5km3.
Water from the Nurek reservoir is also supplied through the 14km-long Dangara irrigation tunnel to irrigate approximately 700km2 of agricultural land. The volume of water utilised for power generation is 4.5km3.
Construction of the multi-purpose dam project was started by the former Soviet Union in 1961. At 300m dam height, it remained the world’s tallest dam structure before it was surpassed by the 305m-tall Jinping-I dam in China in 2013.
Nurek hydropower plant make-up
The underground powerhouse of the Nurek hydroelectric facility is equipped with nine Francis turbine-generator units including eight 335MW and one 320MW unit. The average electricity output of the facility is estimated to be 10,223 million kWh per year.
The electricity generated by the facility is evacuated into the national grid via two onsite switchyards.
The Nurek hydropower facility has a 500kV switchyard and a 200kV switchyard that were refurbished recently.
Nurek switchyard reconstruction
The 500kV switchyard reconstruction project at Nurek involved the replacement of air-insulated outdoor switchyards with gas-insulated indoor switchyards. Concluded in 2016, the switchyard rehabilitation project was executed by Alstom Grid on a turnkey basis.
The Asian Development Bank (ADB) provided funding for the 500kV switchyard reconstruction project, while the reconstructed 220kV switchyard, which was inaugurated in 2013, received funding from Germany’s KfW Development Bank.
Nurek hydropower rehabilitation project details
Three of the total nine power generating units at the facility are being replaced with 380MW Francis turbine and generator units as part of the phase one rehabilitation project.
Phase one also involves the installation of six single-phase autotransformers in the switchyard, the inspection and repair of the nine penstocks, the modernisation of dam monitoring instrumentation, as well as the rehabilitation works on the spillway tunnel, gates and hoisting system to improve dam safety.
The remaining six power generating units of the facility is planned to be replaced in the second phase rehabilitation project at the facility which is expected to continue from 2024 to 2028.
Post rehabilitation, the plant’s total generation capacity is expected to be boosted from the current 2.6GW to 3.3GW.
Financing for Nurek hydropower rehabilitation phase one
The first phase of the hydropower plant rehabilitation project is being financed through £184m ($225.7m) of funding from the World Bank’s lending arm International Development Association (IDA), £49m ($60m) of debt finance from the Asian Infrastructure Investment Bank (AIIB) and a £33m ($40m) loan facility from the Eurasian Development Bank (EDB).
Contractors involved with the Nurek hydroelectric facility modernisation
Andritz Hydro was awarded a contract worth more than £107m ($140m) to supply the electro-mechanical equipment required for the modernisation and refurbishment of the existing nine power generating units at the facility in August 2018.
Tajik SGEM, a local company based in Tajikistan, has been engaged as a sub-contractor, while Switzerland-based engineering consultant Stucky was hired by Barqi Tojik to offer project management services.
Tractebel Engie was engaged to conduct the techno-economic assessment study for the rehabilitation project during 2014 and 2015.
Hydropower rehabilitation projects in Tajikistan
The other hydroelectric power plants undergoing rehabilitation in Tajikistan are the 126MW-Quairokkum plant and the 240MW-Sarband plant which was earlier known as the Golovnaya power station.
The hydropower rehabilitation projects in the country are aimed to meet the increasing domestic electricity demand as well as to export the surplus electricity in the summer months to the Kyrgyz Republic, Afghanistan and Pakistan through the proposed 1,227km-long, Central Asia-South Asia (CASA-1000) 500kV electricity transmission system.