The Dniester Pumped Storage Power Station is a pumped storage hydroelectric scheme that uses the Dniester River 8 km (5 mi) northeast of Sokyriany in Chernivtsi Oblast

Chernivtsi Oblast

Chernivtsi Oblast is an oblast in western Ukraine, bordering on Romania and Moldova. It has a large variety of landforms: the Carpathian Mountains and picturesque hills at the foot of the mountains gradually change to a broad partly forested plain situated between the Dniester and Prut rivers....

, Ukraine. Currently, one of the seven 324 MW generators is operational and when complete, the power station will have an installed capacity of 2,268 MW.

Background

As part of the Dniester Hydro Power Complex, the pumped storage power station (PSP) was planned in the 1970s along with two dams (Dniester I & II) and a nuclear power plant. In 1983, Dniester II, a dam which creates the PSP's lower reservoir, was completed. The PSP was approved by 1988 and construction began that same year. Three years later in 1991 though, construction was suspended due to a funding fallout from the dissolution of the Soviet Union

Dissolution of the Soviet Union

The dissolution of the Soviet Union was the disintegration of the federal political structures and central government of the Union of Soviet Socialist Republics , resulting in the independence of all fifteen republics of the Soviet Union between March 11, 1990 and December 25, 1991...

. The project was re-approved in 1993 and construction commenced again in 2001. Project costs increased due to the poor state of the existing facilities which were not maintained while the project was suspended. On December 22, 2009, the PSP's first generator was commissioned. The second and third generators of the first stage are expected to be operational in 2011 and 2012, respectively. Ukraine's problems funding the project have been compounded by controversy surrounding the project's transparency and impacts on the environment and water flow to Moldova

Moldova

Moldova , officially the Republic of Moldova is a landlocked state in Eastern Europe, located between Romania to the West and Ukraine to the North, East and South. It declared itself an independent state with the same boundaries as the preceding Moldavian Soviet Socialist Republic in 1991, as part...

 downstream. Ukraine had sought funding from the World Bank

World Bank

The World Bank is an international financial institution that provides loans to developing countries for capital programmes.The World Bank's official goal is the reduction of poverty...

 who, in 2007, only funded US$29.6 million towards the PSP's electrical transmission system. Industry experts believe Ukraine will be able to complete the project independently. The power station is expected to be fully operational in 2017.

Design and operation

The power station begins operation by using reversible turbines to pump water, during low energy demand periods, from the lower reservoir which is created by the Dniester HPP-II Dam, located 7.5 km (5 mi) to the southeast near the border with Moldova at 48°29′16"N 27°34′07"E. The lower reservoir has a storage capacity of 70000000 cubic metre. Water pumped from this reservoir is placed in the upper reservoir which is formed by a 360° "liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

"-shaped embankment dam

Embankment dam

An embankment dam is a massive artificial water barrier. It is typically created by the emplacement and compaction of a complex semi-plastic mound of various compositions of soil, sand, clay and/or rock. It has a semi-permanent waterproof natural covering for its surface, and a dense, waterproof...

. The upper reservoir has a 38800000 cubic metre storage capacity. During periods of high energy demand, water is released from the upper reservoir back to the power station for generation. This process is routinely repeated and helps balance loads

Load balancing (electrical power)

Load balancing refers to the use of various techniques by electrical power stations to store excess electrical power during low demand periods for release as demand rises....

. The difference in the two reservoirs affords a hydraulic head

Hydraulic head

Hydraulic head or piezometric head is a specific measurement of water pressure above a geodetic datum. It is usually measured as a water surface elevation, expressed in units of length, at the entrance of a piezometer...

 of 38.7 m (127 ft).

While only one is currently operational, the power station will contain seven 324 MW reversible Francis turbine

Francis turbine

The Francis turbine is a type of water turbine that was developed by James B. Francis in Lowell, Massachusetts. It is an inward-flow reaction turbine that combines radial and axial flow concepts....

generators. Its installed capacity will be 2,268 MW when generating and during pumping, the power station will consume a maximum of 2,947 MW. Regulating flows into the lower reservoir is the Dniester HPP-I Dam which is located upstream, 9 km (6 mi) north of the power plant at 48°35′37"N 27°27′10"E. HPP-I has its own power plant with an installed capacity of 702 MW and a storage capacity of 3000000000 cubic metre. HPP-II has an installed capacity of 40.8 MW.