Gilgel Gibe II is currently Ethiopia’s most powerful hydroelectric plant with an installed capacity of 420 MW. Voith supplied four Pelton turbines and generators as well as the entire mechanical and electrical equipment and also trained the plant operator’s staff. The project raised Ethiopia’s hydro capacity by over 50 per cent. Before Gilgel Gibe II went into operation, only 15 per cent of Ethiopia’s villages were connected to the power grid. Now, half of the rural settlements are supplied with power.
A 500 meter water drop for 350 km/h runner speed
Gilgel Gibe II uses the water of the older Gilgel Gibe I plant, upstream on the Gibe river. About 500 meters above the powerhouse, the water is directed from the concrete-lined tunnel into two steel penstocks which then run along the surface. After a horizontal section, the gradient drops and the water rapidly picks up speed. After a few hundred meters, the penstocks bifurcate into four distribution pipes, feeding the runners of the Pelton turbines. The water will then be directed to the buckets of the runners through six jet nozzles, which turn the almost three and a half meter diameter turbine runners to 333 revolutions per minute.
Both, the generators and Pelton runners, were manufactured by Voith in São Paulo, Brazil. Their hydraulic profile was optimized at the company’s facilities in Heidenheim, Germany. State-of-the-art design technology allows minimal energy loss when the water jet impacts the runners at a velocity of over 350 kilometers an hour.
Reliable production of energy to sustain Ethiopia’s development
These turbine-generator units will be transforming the energy of the water into electricity for many decades to come with no fuel cost. Ethiopia, like any other developing nation, is dependent on reliable and low-cost production of energy to sustain its development.