Nenskra Hydroelectric Project

Name of Project:
Nenskra Hydroelectric Project


Country:
Georgia

Client:
JSC Nenskra Hydro consortium (composed of the Korea Water Resources Corporation [K-water], a government agency, and by the Georgian Government)

Type of contract:
EPC

Total value:
$ 575 million

Start of works:
September 2015

Expected duration:
62 Months

The Nenskra hydroelectric project (greenfield) will have an installed power equal to 280MW and will guarantee the energy supply needed during the winter season while maximising the export capacity during the summer season.

The project consists of a dam, pressure tunnel, surge tank, penstock and powerhouse. Additionally a transfer tunnel will convey the water from Nakra river to the new Nenskra dam reservoir to improve the performance of the Project. An asphalt faced rockfill dam (AFRD) has been selected considering the site conditions in the Nenskra river basin. The peculiarity of the structure is the 65 m deep Cut-Off wall to be realized throughout the alluvial deposit on the river bed.
The other main ancillary structures to the dam are:

  • The Bottom Outlet structure (tunnel with gate shaft)
  • The Spillway Structure (tunnel with lateral over flow structure and unlined plunge pool)

The project is capable of providing on average total energy generation of 1219 GWh/y, 259,2 GWh of guaranteed supply in the winter months and maximizes export benefits in the summer months. The power will be distributed through a 220 kV transmission line to Akhari-Jvari substation

MAIN TECHNICAL DATA:
Intake weir on the River Nakra with 9m height, 50m crest length
Nakra Transfer Tunnel with length of 14.4km and 3.5m diameter excavated by TBM
Asphalt-facedrockfill dam with 135m height and 850m crest length (Storage: 183 million m3)
Headrace tunnel (Intake ~ Surge shaft) with length of 15.6km and 4.5m diameter excavated with TBM

Surface powerhouse: 280 MW (4x70MW) with no. 4 Pelton turbines @ 70MW

Net Head: 679m
Rated Discharge: 12m3/unit, total 48m3/sec
Surge Shaft 184 m deep, with an excavated diameter of 14m and an internal final diameter of 12 m. The calculated maximum water level in the surge tank shall be 1481.00masl (sudden simple closure) and the minimum water level 1389.00 masl (sudden simple closure).