| Large dams Isimba Dam Isimba Dam, Uganda


The Isimba Hydropower Project is a testament to Uganda’s commitment to addressing its power shortages and fostering economic growth. Situated approximately 50km downstream of Jinja on the White Nile River, this run-of-the-river hydroelectric plant was commissioned in March 2019 and has since become an integral part of the country’s energy infrastructure. The dam boasts an impressive installed capacity of 183.2MW, generated by four vertical Kaplan turbine-generator units. Each of these units is capable of producing 45.8MW, operating at a gross head of 15.4m and an average flow rate of 1,375m3


/sec. This


configuration allows the project to generate an estimated 1,039 GWh of electricity annually, significantly boosting Uganda’s total electric capacity by 23%. The dam’s structure is a marvel of engineering, consisting of two primary components. On the left bank stands a concrete gravity dam, measuring 14m in height and stretching 314m in length. Complementing this is a rock-fill embankment dam on the right bank, reaching a maximum height of 26.5m. While the concrete dam serves as the main reservoir retaining structure, the rock-fill dam houses essential emergency gates and stop logs. In terms of land use, the Isimba project


extends over approximately 2,867.6 acres. At its maximum flooding level, the reservoir can stretch up to 5.7km upstream, potentially impacting the Kalagala Falls site area. This expansive footprint underscores the project’s scale and its potential environmental implications. The power generated at Isimba is transmitted


to the national grid via a 42-kilometer-long 132kV double-circuit transmission line, connecting to the Bujagali hydropower station. This integration into the national power infrastructure is facilitated by the Isimba substation, which features a double busbar


Isimba Dam


configuration. The substation includes two line bays, four transformer bays, one bus coupler, and two future bays, ensuring efficient power distribution and allowing for future expansion. Environmental and social considerations were paramount in the development of the Isimba hydropower project. An Environmental and Social Impact Assessment (ESIA) addendum was prepared to address key issues raised by the National Environmental Management Authority (NEMA), particularly concerning the Kalagala Offset Area. The construction of the dam has had significant effects on the local ecosystem and communities, including the flooding of the home of the Budhagaali spirit, an important water spirit in the Busoga Kingdom’s culture. To mitigate these impacts, a comprehensive Community Development Action Plan (CDAP) was implemented, which included the construction of medical centers, schools, and public toilets. From an economic perspective, the Isimba


project represents a substantial investment of approximately $567.7 million. This funding was secured through a combination of government contribution ($85 million) and a loan from the Export-Import Bank of China ($482.5 million). The project is expected to generate electricity at a competitive rate of 68 cents per kWh, positioning it as the lowest-cost producer in East Africa. Beyond power generation, the project has yielded significant socio-economic benefits. During its construction phase, it created approximately 1000 jobs, contributing to local employment and skill development. Furthermore, the project included the construction of the Isimba Public Bridge, enhancing transportation links between the Kayunga and Kamuli districts and fostering regional connectivity.


Laúca Dam, Angola


The Laúca project is located on the Kwanza River in Angola. Commissioned in stages between 2017 and 2020, this run-of-the-river hydroelectric project boasts a total capacity of 2070MW, making it the second-largest hydroelectric facility in Africa, after the 2075MW Cahora Bassa power station in Mozambique. The project features a 132m-high roller compacted concrete (RCC) dam with a crest length of approximately 1075m. This massive structure creates a reservoir with a capacity of 5,482 million m3 200km2


, spanning an area of nearly . At the heart of the Laúca power plant are six


main vertical axis Francis turbines, each with a capacity of 334MW. These turbines operate at a net head of 200m with a nominal flow rate of 182m3


Ilisu Dam, Turkey


/sec. The main powerhouse, measuring 273m in length and 21min width, is constructed underground to house these turbine units. In addition to the main powerhouse, the


project includes an ecological power plant with


The Ilısu Dam, located on the Tigris River in southeastern Turkey, was commissioned in stages between 2019 and 2020. This concrete- faced rockfill dam is a key component of the Southeastern Anatolia Project (GAP), which


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Laúca Dam


a capacity of 65.5MW, situated at the base of the dam. This smaller plant features a single vertical axis Francis turbine operating with a nominal flow rate of 60m3/sec and a net head of 128m. The Laúca plant’s design incorporates advanced features for efficient water management and power generation. The water conveying system comprises six


water intakes and six wells, each with an inner diameter of 7m. The spillway is designed to handle a flow rate of 10,020 cubic meters per second, ensuring the dam’s safety during high water events.


Power evacuation from the main plant is


achieved through a 400 kV transmission line, while a separate 220 kV ancillary substation handles power from the ecological plant. This robust transmission infrastructure enables the Laúca plant to supply electricity to approximately 8 million Angolan households and contribute significantly to the country’s power grid stability. The plant’s annual electricity generation capacity is estimated at 8,640 GWh, a substantial contribution to Angola’s energy mix. This output has played a crucial role in reducing power shortages and eliminating the need for daily power rotations in Luanda, the capital city. Technologically, the Laúca plant incorporates modern control and monitoring systems. The ANDRITZ Metris DiOMera system enables remote monitoring and enhanced functionality, including predictive maintenance capabilities. This advanced system allows for efficient plant management and can potentially extend maintenance intervals, resulting in both environmental and economic benefits. The construction of the Laúca Hydroelectric Power Plant represented a significant investment of approximately $4.3 billion. This funding was secured through a combination of government investment and international financial institutions, including the Development Bank of Southern Africa, Standard Chartered, and Gemcorp Capital.


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