The Gilgel Gibe II Power Station is a

hydroelectric Hydroelectricity, or hydroelectric power, is electricity generated from hydropower (water power). Hydropower supplies one sixth of the world's electricity, almost 4500 TWh in 2020, which is more than all other renewable sources combined and ...

power station A power station, also referred to as a power plant and sometimes generating station or generating plant, is an industrial facility for the generation of electric power. Power stations are generally connected to an electrical grid. Many p ...

on the

Omo River The Omo River (also called Omo-Bottego) in southern Ethiopia is the largest Ethiopian river outside the Nile Basin. Its course is entirely contained within the boundaries of Ethiopia, and it empties into Lake Turkana on the border with Kenya. The ...

Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...

. It is located about east of

Jimma Jimma () is the largest city in southwestern Oromia Region, Ethiopia. It is a special zone of the Oromia Region and is surrounded by Jimma Zone. It has a latitude and longitude of . Prior to the 2007 census, Jimma was reorganized administrative ...

in Wolaita/Dawro Region. The power station receives water from a tunnel entrance on the

Gilgel Gibe River Gilgel Gibe River (with ''Gilgel'' meaning ''Little'') is a major tributary of the larger Gibe River in southwest Ethiopia in western Oromia Region. It flows in an arc through the south of the Jimma Zone, defining part of the Zone's boundary with ...

. 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 completed 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 Sluice ( ) is a word for a channel controlled at its head by a movable gate which is called a sluice gate. A sluice gate is traditionally a wood or metal barrier sliding in grooves that are set in the sides of the waterway and can be considered ...

on the Gilgel Gibe River. The headrace tunnel runs under the Fofa Mountain and at its end, it converts into a

penstock A penstock is a sluice or gate or intake structure that controls water flow, or an enclosed pipe that delivers water to hydro turbines and sewerage systems. The term is inherited from the earlier technology of mill ponds and watermills. H ...

with a drop. When the water reaches the power station, it powers four

Pelton turbine The Pelton wheel or Pelton Turbine is an impulse-type water turbine invented by American inventor Lester Allan Pelton in the 1870s. The Pelton wheel extracts energy from the impulse of moving water, as opposed to water's dead weight like the trad ...

s that operate four 107 MW generators. Each turbine is in diameter.

Construction

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 Kato Vermio-Seli ( el, Κάτω Βέρμιο, before 1926: Κάτω Σέλι - ''Kato Seli'', rup, Selia de Jos) is, primarily, an Aromanian (Vlach) Greek village and a community of the Veria municipality. Since the 2001 local government reform ...

and in October 2006, a

tunnel boring machine A tunnel boring machine (TBM), 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 may also be used for microtunneling. They can be designed to bore throu ...

(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 and repair

About ten days after the project was completed, about of the headrace tunnel collapsed. The collapse may have been attributed it to structural failure caused by expedited construction and a lack of proper studies.International Rivers
Ethiopian Dam Suffers Tunnel Collapse Days After Inauguration
Published 5 February 2010. Accessed 13 June 2010. 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.

Financing

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 Bank The European Investment Bank (EIB) is the European Union's investment bank and is owned by the EU Member States. It is one of the largest supranational lenders in the world. The EIB finances and invests both through equity and debt solutions ...

, and the remaining €103 million from the Ethiopian Government.

Controversy

The financing of the power plant was controversial within the Italian government. It was granted despite objections raised by the Directorate General for Development Cooperation of the Ministry of Foreign Affairs and the Ministry of Economy and Finance. They argued against the loan because the contract was awarded without competitive bidding in breach of Italian law, because its unusually large size meant that less funding was available for other development projects, no costs for environmental impact assessment of monitoring were included, the project was not commercially viable due to low electricity tariffs in Ethiopia and because it was inappropriate to burden such a poor country with more debt at a time when it had just received debt relief from Italy. There were also parliamentary questions concerning the project which were left unanswered by the Undersecretary of State for Foreign Affairs, Luigi Mantica. In March 2006 the Prosecutors’ Office in Rome instigated criminal proceedings concerning the Gilgel Gibe II hydroelectric project.

References