The Isimba hydropower project is a run-of-the-river hydroelectric plant located on the Nile River, approximately 4km downstream of Simba Falls, in the Kamuli district of Uganda.
Feasibility study of the $567.7m Isimba project was completed in September 2012 and construction was started in April 2015. The project was commissioned in March 2019 and is expected to generate 1,039 gigawatt hours (GWh) of electricity a year.
The Ministry of Energy & Mineral Development, Government of Uganda (GoU) fully owns the hydropower project. Uganda Electricity Generation Company (UEGCL) was responsible for the project implementation.
Isimba hydropower project background
The Isimba hydropower project is developed in line with the Government of Uganda’s National Development Plan NDP II and Vision 2040, which are aimed at generating sufficient electricity to meet the future needs of Uganda.
The project was under constant scrutiny, since the reservoir at its maximum flooding level can extend 5.7km upstream into the Kalagala Falls site area and flood three rapids in the Victoria Nile River.
The GoU revised the guidelines for the project development and signed an amended indemnity agreement (IA) with International Development Association (IDA) in January 2018.
Isimba hydropower plant location and make-up
The Isimba hydropower project is located on the Nile River, approximately 50km downstream of Jinja, Uganda.
The project includes a concrete gravity dam on the left bank, a rock-fill embankment dam on the right bank, a spillway, a power house, switching yard, and power transmission lines. The concrete dam provides a reservoir retaining structure in front of the erection bay, while the rock-fill dam features emergency gates and stop logs.
The Isimba power house features four 48.5MW vertical Kaplan turbine and generator units. The concrete gravity dam is 14m-tall and 314m-long, while the embankment dam has a maximum height of 26.5m. The Isimba hydroelectric plant is designed to operate at a gross head of 15.4m and an average flow rate 1,375m³/s of water.
The switchyard of the project comprises a double busbar substation with two line bays, four transformer bays, one bus coupler, and two future bays.
Transmission of power generated from Isimba HPP
Power generated at the Isimba hydropower project is transmitted to the national grid through a 42km-long 132kV double-circuit transmission line connecting the Bujagali hydropower station.
The Government of Uganda provided funding of $85m, which accounts for 15% of the total project cost, while the Export-Import Bank of China provided a loan of $482.5m.
China International Water & Electric Corporation (CWE) was awarded the engineering, procurement, and construction (EPC) contract for the Isimba hydropower project in August 2013.
The joint venture of Fichtner and Norplan drafted the feasibility study report of the project, under a $3.8m contract awarded in 2010.
Energy Infratech, a company based in India, served as the owner’s engineer for the project until September 2017. The consortium of Artelia Eau & Environment and KKATT Consult was appointed as the owner’s engineer in January 2018.