Tekeze Hydropower project named best Renewable/Sustainable Project of the year

Tigrai Online
Dec. 15 2010

Tekeze Hydropower project named best Renewable/Sustainable Project of the yearThe Tekeze Hydropower project in Ethiopia, located on the Tekeze River, a tributary of the Nile, is the Project of the Year for renewable/sustainable projects. The $350 million project, funded by the government of Ethiopia and owned by Ethiopian Electric Power Corp., adds 40 percent more electric capacity to the country and was the largest public works project in Ethiopiaís history at the time of construction. Due to the lack of natural resources and the cost of imported fuels, power generation in Ethiopia comes primarily from hydroelectric sources.

The Tekeze Hydropower project is the tallest arch dam in Africa at 188 meters. The 300 MW facility includes a double curvature concrete arch dam, a method of design that minimizes the amount of concrete used. It created a reservoir 70 kilometers in length. An underground powerhouse containing four 75 MW Francis Turbines sits 500 meters downstream of the dam and is fed by a 75-meter-high intake structure connected by a 500-meter-long concrete-lined power tunnel. A 230 kV double-circuit transmission line 105 kilometers long was constructed through mountainous terrain to connect to the Ethiopian national grid.

The projectís beginnings date back to 1995 when the Ethiopian Ministry of Water Resources conducted a study identifying the site as one of two preferred dam sites for hydropower development. MWH joined the project in 1998 and made modifications to an existing design for the dam, powerhouse and tunnel system, resulting in cost savings.

A multi-stage impoundment approach was implemented during construction, which allowed the river diversion to be closed in May 2007, nearly two years prior to dam completion. This allowed for more than 3 billion m3 of water to be retained, advancing generation by more than one full year. The value of the water captured via early impoundment was worth approximately $40 million. In addition to power generation, the Tekeze dam enables regulation of river flow, allowing downstream communities year-round access to the water supply.

A 10-year 2000m3/sec flood on Aug. 9, 2006 was an unexpected test for the dam. The dam proved its ability as a gravity structure and no damage was incurred to any of the permanent structures.

Local community infrastructure was improved as a result of the project, including construction of more than 40 kilometers of roads and installation of the first communications links from the area to the outside world. Also as a result of the project, education was improved in the area as the wife of the MWH chief design engineer spearheaded efforts to build a new school near the village of Seboko. The school was financed by contributions from engineers, contractors and staff working on the project, local residents and a supportive local government.

On-the-job training was also provided to locally-hired employees. Ethiopian Electric Power Corp. implemented programs to provide education and training to local workers. Programs included education to combat AIDS, malaria and other safety, health and welfare issues affecting the local community.