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The Vorotan Cascade, or the ContourGlobal Hydro Cascade,[5] is a cascade on the Vorotan River in Syunik Province, Armenia. It was built to produce hydroelectric power and provide irrigation water. The Vorotan Cascade consists of three hydroelectric power plants and five reservoirs with a combined installed capacity of 404.2 MW. It is one of the main power generation complexes in Armenia.[6] [7]
The planning process of the Cascade began just after the Conference of the State Planning Commission held in 1951. In 1954, it was highlighted that with proper infrastructure and careful planning, Armenia's energetic hydro resources might allow it to become an electricity exporter to neighbouring energy deficit areas like Azerbaijan and Iran. It was anticipated that the activation of the Cascade would cut the import of oil products to the country by half. The design work of the Complex began in 1954 and it was constructed between 1961 and 1989. The Tatev hydroelectric power plant (HPP) was completed in December 1970, the Shamb HPP in 1978, and the Spandaryan HPP] in 1989.[8] Despite the plans, Azerbaijan was against the import of electricity from Armenia, thus hindering the scheduled renovation and capacity expansion to take place at the end of the 1970s. The Vorotan Cascade continued to supply electricity mainly to non-ferrous metallurgy industry in nearby Agarak.
After Armenia gained independence, the Voratan Cascade belonged to the state-owned energy company Armenergo. In 1997, the Vorotan cascade was separated from Armenergo into a separate state owned company.[9]
Modernization of the cascade started in 2003 by help of the €2.7 million grant of the European Union which was used for rehabilitation of the Tatev HPP of the Vorotan Cascade, and the Argel HPP. Rehabilitation works were conducted by Voith Siemens Hydro Power Generation. Next rehabilitation project was launched in 2010, financed by the €51 million credit from the German development bank KfW.[10] Rehabilitation works started in 2012.[11]
In 2015, ContourGlobal purchased the Vorotan Cascade operating company for US$180 million.[12] ContourGlobal has started a six-year refurbishment program to modernize the plants and improve their operational performance, as well as safety, reliability, and efficiency, with the total investment of $70 million.[11] [13] This is the biggest investment US investment in Armenia. The International Finance Corporation, a member of the World Bank Group, did 20% of the total investment.[12]
The Vorotan River has length of, the fall of, and the natural annual flow of for the link of Tatev. The source of the river is on of the height and starts like a stream, accepting numerous ponds and streams.
The Vorotan Cascade includes a system of three power plants which are Spandaryan, Shamb and Tatev, and five reservoirs which are Spandaryan, Angeghakot, Tolors, Tatev and a daily regulation reservoir.[7] The Spandaryan Reservoir in the vicinity of Tsghuk and Gorhayq villages, is the starting point of the complex. From there water flows through a pressurized tunnel to the Spandaryan HPP. From the Spandaryan HPP water flows to the Angeghakot Reservoir and continues its journey to the Tolors Reservoir which is located in the area of Sisian and Ayri. From that reservoir the water flows to the Shamb HPP. From Shamb reservoir that was constructed beyond the Shamb HPP water reaches the regulation pool, from where it proceeds to the Tatev HPP via a turbine pipe.[8]
| Power Plant | Year | Units | Installed Capacity (MW) | Coordinates | |
|---|---|---|---|---|---|
| Spandaryan HPP | 1989 | 2 X 38 MW | 76 | ||
| Shamb HPP | 1978 | 2 X 85.5 MW | 171 | ||
| Tatev HPP | 1970 | 3 x 52.4 MW | 157.2 | ||
| Total | 7 | 404.2 |
The Vorotan Cascade is one of the main power generation complexes in Armenia. It provides both peak and base load power. It is used also for the grid stabilization.[7] The Tatev HPP has installed capacity of 157.2 MW, the Shamb HPP has installed capacity of 171 MW, and the Spandaryan HPP has installed capacity of 76 MW. Total installed capacity of Vorotan Cascade is 404.2 MW and it generates 1.16 GWh of electricity annually.[8]
The water stores of the Vorotan Complex are also used for irrigation in nearby village and town areas.[6]
The Tatev HPP is located near the Vorotan village on the left bank of the Vorotan River at the altitude of .[14] It is one of Armenia's largest hydroelectric power plants, with installed capacity of and annual generation of 670 GWh.[8] Power is generated by three Pelton turbines of each.[15] The plant is unique has it is the highest-head hydroelectric power plant in the territory of the former Soviet Union and by using Pelton turbines.[8]
The plant includes the Tatev Dam which is a 41m (135feet) high and 107m (351feet) embankment type dam of sandy gravel. It includes also the daily regulation reservoir.[7] The dam creates the Tatev Reservoir.[8]
The water intake on the left bank of the Vorotan River has capacity of and the spillway has total capacity of . Water runs from the water intake through the 18km (11miles) long free-flow diversion tunnel to the delivery chamber. The 139.4m (457.3feet) long and 4m (13feet) high tail-water canal is connected with an irrigation water outlet. The pressure chamber has a diameter of and the threshold level of . It is connected to the plant by a 1855m (6,086feet) pressure conduit, and to the 80000m2 daily regulation reservoir by the sluice-feeder. The rated head of the plant is .[8]
The Shamb HPP is located near the village of Shamb on the right bank of the Vorotan River at the altitude of .[14] It is one of the largest hydroelectric power plant having an installed capacity of and annual generation of 320 GWh.[8]
Shamb HPP includes the Angeghakot and Tolors dams which create the Angeghakot and Tolors reservoirs. The Angeghakot Dam is a 23.4m (76.8feet) high concrete spillway dam.[8] The Tolors Dam is a 69m (226feet) high and 188m (617feet) long embankment type dam of sandy gravel and soil.[8] [7] The Angeghakot and Tolors reservoirs are connected by a 10.5km (06.5miles) free-flow tunnel which has throughput capacity of . Water runs from the Tolors Reservoir to the plant through a 6.9km (04.3miles) diversion pressure tunnel which turns into a 1260m (4,130feet) single-lane penstock.[8]
The Spandaryan HPP is located near Shaghat at the altitude of .[14] It is the upper hydroelectric power plant on the cascade commissioned in 1989. The plant has an installed capacity of 76 MW and a projected annual electricity generation of 210 GWh.[8]
The Spandaryan Dam creates the cascade's upper reservoir, the Spandaryan Reservoir. The 83m (272feet) high and 315m (1,033feet) long Spandaryan dam is an embankment type, mixed rockfill and earthfill with clayey soiled bottom.[7]
Its water intake infrastructures includes a pressure tunnel, a spillway culvert, and the Vorotan–Arpa tunnel for releasing water into Lake Sevan. The structures have, and water outlays respectively. The last, the fourth structure is a surface spillway with a installed capacity and inclining drop. The pressure tunnel is long and it ends with a surge tank with capacity of . The surge tank is connected to plant by 2168m (7,113feet) penstock.[8]
Spandaryan Reservoir is located southeast of Gorayk, in Spandaryan in the Vorotan River basin. It is connected to Arpa River and Arpa River basin by a 9miles long tunnel.[16] It reportedly has a breeding colony of lesser kestrels, the only known in Armenia.[17]
The reservoir's length is, its width varies from 2.5to, and its depth is . The surface area of the reservoir is .[18] It has 218000000m2 active and 257000000m2 total capacities. The normal elevation of water level is while is the absolute minimum.[8]
The Angeghakot Reservoir has 3400000m2 of total capacity. The reservoir has throughput capacity of and the spillway has capacity of .[8]
The Tolors Reservoir has a total capacity of 96000000m2 and active capacity of 80000000m2. The normal elevation of water level is while is the minimum.[8]
The Tatev Reservoir has total capacity of 13600000m2 and active capacity of 1800000m2. The normal elevation of water level is while is the minimum.[8]