The Gilgel Gibe III Dam is a 250 m high roller-compacted concrete dam with an associated hydroelectric power plant on the Omo River in Ethiopia. It is located about 62 km (39 mi) west of Sodo in the South Ethiopia Regional State. At the time of its full commissioning the dam was the third largest hydroelectric plant in Africa with a power output of about 1,870 Megawatt (MW), thus more than doubling Ethiopia's total installed capacity from its 2007 level of 814 MW. The Gibe III dam is part of the Gibe cascade, a series of dams including the existing Gibe I dam (184 MW) and Gibe II power station (420 MW) as well as the planned Gibe IV (1,472 MW) and Gibe V (560 MW) dams. The existing dams are owned and operated by the state-owned Ethiopian Electric Power, which is also the client for the Gibe III Dam. The US$1.8 billion project began in 2006, electricity generation started in October 2015. The remaining generators were operational by 2016. The project has experienced serious delays; in May 2012, full commissioning had been scheduled for June 2013. The dam was inaugurated by Prime Minister Hailemariam Desalegn on 17 December 2016. Local and international environmental groups forecast major negative environmental and social impacts of the dam and criticized the project's environmental and social impact assessment as insufficient. Because of this and accusations that the entire approval process for the project was suspect, funding for the full construction cost was not secured, as the African Development Bank delayed a decision about a loan pending a review of the dam's environmental impact by its compliance review and mediation unit. This dates back to August 2009 when they accepted a call from NGOs for such a review. In August 2010 Ethiopian Prime Minister Meles Zenawi vowed to complete the dam "at any cost", saying the dam's critics "don’t want to see Africa developed; they want us to remain undeveloped and backward to serve their tourists as a museum."
Design The Gilgel Gibe III Dam is 610 m-long (2,000 ft) and 243 m (797 ft) high roller-compacted concrete dam. It withholds a reservoir capacity of 14.7 km3 (3.5 mi3) and a surface area of 210 km2 (81 mi2), collected from a catchment area of 34,150 km2 (13,190 mi2). The reservoir's live (active or "useful") storage is 11.75 km3 (2.82 mi3) and dead storage of 2.95 km3 (0.71 mi3). The normal operating level of the reservoir is 892 m (2,927 ft) above sea level with a maximum of 893 m (2,930 ft) and a minimum of 800 m (2,600 ft). The dam's spillway is 108 m (354 ft) long and floodgate-controlled with a maximum discharge capacity of 18,000 m3/s (640,000 cu ft/s). Water above 873 m (2,864 ft) above sea level can be discharged through its gates. Feeding the dam's power house are two penstocks that each branch into five separate tunnels for each individual turbine. The power house contains ten 187 MW generators supported by Francis turbines for a total installed capacity of 1,870 MW. The initial design of the dam foresaw a rock-fill dam. However, due to difficulties with obtaining proper and sufficient insurance coverage for the rock-fill dam, the design was changed to roller-compacted concrete.
Benefits The main benefit of the dam is electricity generation that is both renewable and dispatchable. It was forecast to supply about half of its power to Ethiopia and export the other half to Kenya (500 MW), Sudan (200 MW) and Djibouti (200 MW). However, there were long delays in making Power Purchase Agreements. Only Kenya signed a Memorandum of Understanding to purchase electricity from the dam. Financing for a transmission line to Kenya was approved by the World Bank in July 2012. Access to the electricity grid in Ethiopia currently is very low. Less than 2% of Ethiopia's rural population, which accounts for 85% of the total population, have access to the grid. With the support of the World Bank the government is carrying out an ambitious project to expand rural electricity access. In 2003, low generation capacity combined with a severe drought caused power cuts lasting 15 hours twice a week for a period of six months, costing an estimated $200 million in economic output. In 2008 and 2009, Ethiopia again experienced power cuts and brownouts. According to the International Rivers Network the power cuts were caused by drought, because almost all electricity generation in Ethiopia is hydroelectric. According to the same source, despite an increase in access to the electric grid, electricity consumption is likely to remain low for the foreseeable future due to the prevailing level of poverty. Even without the Gibe III hydro plant, according to one source, Ethiopia had a surplus installed capacity of 400 megawatts. Under Ethiopia's current development plans it is said the country will be more than 95% dependent on hydroelectric power. Ethiopia has predicted that electricity exports will generate around $407 million revenue per year, exceeding the value of the country's next most valuable export, coffee. A secondary benefit of the project is flood protection. In 2006, a flood claimed the lives of at least 360 people and thousands of livestock in the lower Omo River basin. A further benefit is the reduction in the impact of droughts, including through large state-owned irrigated sugar plantations.
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