Gilgel Gibe II Power Station
Encyclopedia
The Gilgel Gibe II Power Station is a hydroelectric power station
on the Omo River
in Ethiopia
. The power station receives water from a tunnel entrance 7°55′27"N 37°23′16"E on the Gilgel Gibe River
. It has an installed capacity of 420 MW and was inaugurated on January 14, 2010. Almost two weeks after inauguration, a portion of the head race tunnel collapsed causing the station to shut down, repairs were complete on December 26, 2010.
, and the remaining €103 million from the Ethiopian Government. Construction on the power plant began on March 19, 2005, with Salini Costruttori as the main contractor. The power station was originally slated to be complete in late 2007 but was delayed because engineering problems encountered during construction. In March 2005, the contract to excavate the tunnel was awarded to SELI
and in October 2006, a tunnel boring machine
(TBM) hit a fault, delaying the project. On June 9, 2009, both TBMs met each other and the tunnel was ready for hydraulic testing that September. The tunnel is "considered one of the most difficult tunnel projects ever undertaken, due to the critical, and in some reaches, exceptionally adverse, ground conditions." The power station was inaugurated on January 14, 2010.
with a 500 m (1,640.4 ft) drop. When the water reaches the power station, it powers four Pelton turbines that operate four 107 MW generators
. Each turbine is 3.5 m (11.5 ft) in diameter.
Power station
A power station is an industrial facility for the generation of electric energy....
on the Omo River
Omo River
The Omo River is an important river of southern Ethiopia. Its course is entirely contained within the boundaries of Ethiopia, and empties into Lake Turkana on the border with Kenya...
in Ethiopia
Ethiopia
Ethiopia , officially known as the Federal Democratic Republic of Ethiopia, is a country located in the Horn of Africa. It is the second-most populous nation in Africa, with over 82 million inhabitants, and the tenth-largest by area, occupying 1,100,000 km2...
. The power station receives water from a tunnel entrance 7°55′27"N 37°23′16"E on the Gilgel Gibe River
Gilgel Gibe River
Gilgel Gibe River is a tributary of the Gibe River in southwest Ethiopia. It flows in an arc through the south of the Jimma Zone, defining part of the Zone's boundary with that of the Southern Nations, Nationalities, and Peoples Region west of the Omo River as it turns north...
. It has an installed capacity of 420 MW and was inaugurated on January 14, 2010. Almost two weeks after inauguration, a portion of the head race tunnel collapsed causing the station to shut down, repairs were complete on December 26, 2010.
Background and construction
In 2004, the Government of Ethiopia secured €220 million from the Government of Italy for construction. The total cost of construction is €373 million with €50 million provided by the European Investment BankEuropean Investment Bank
The European Investment Bank is the European Union's long-term lending institution established in 1958 under the Treaty of Rome. A policy-driven bank, the EIB supports the EU’s priority objectives, especially European integration and the development of economically weak regions...
, and the remaining €103 million from the Ethiopian Government. Construction on the power plant began on March 19, 2005, with Salini Costruttori as the main contractor. The power station was originally slated to be complete in late 2007 but was delayed because engineering problems encountered during construction. In March 2005, the contract to excavate the tunnel was awarded to SELI
Seli
Seli is a mountainous-alpine village and winter sports resort located in the Vermion Mountains of northern Greece. The village of Seli is located at a distance of 22km from Veria and 93km from Thessaloniki, in the prefecture of Imathia, Central Macedonia-Greece. It is also known as Kato Vermion...
and in October 2006, a tunnel boring machine
Tunnel boring machine
A tunnel boring machine also known as a "mole", is a machine used to excavate tunnels with a circular cross section through a variety of soil and rock strata. They can bore through anything from hard rock to sand. Tunnel diameters can range from a metre to almost 16 metres to date...
(TBM) hit a fault, delaying the project. On June 9, 2009, both TBMs met each other and the tunnel was ready for hydraulic testing that September. The tunnel is "considered one of the most difficult tunnel projects ever undertaken, due to the critical, and in some reaches, exceptionally adverse, ground conditions." The power station was inaugurated on January 14, 2010.
Tunnel collapse
The exact date is unknown but about ten days after the project was completed, about 15 m (49.2 ft) of the 26 km (16.2 mi) headrace tunnel collapsed. The collapse may have been attributed it to structural failure caused by expedited construction and a lack of proper studies. The official statement of the construction firm Salini Costruttori, released two weeks after the official inauguration was that "an unforeseen geological event provoked a 'cave in' and a huge rock fall involving about 15m of the 26km headrace tunnel." The tunnel was repaired and the station operational again on December 26, 2010.Design
The Gilgel Gibe II consists of a power station on the Omo River that is fed with water from a headrace tunnel and sluice gate on the Gilgel Gibe River. The headrace tunnel runs 26 km (16.2 mi) under the Fofa Mountain and at its end, it converts into a penstockPenstock
A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydraulic turbines and sewerage systems. It is a term that has been inherited from the technology of wooden watermills....
with a 500 m (1,640.4 ft) drop. When the water reaches the power station, it powers four Pelton turbines that operate four 107 MW generators
Electrical generator
In electricity generation, an electric generator is a device that converts mechanical energy to electrical energy. A generator forces electric charge to flow through an external electrical circuit. It is analogous to a water pump, which causes water to flow...
. Each turbine is 3.5 m (11.5 ft) in diameter.