Karuma hydropower plant is a run-of-the-river project being built on the Nile River downstream of the Kyoga Lake in Kyandongo district, 270km from Kampala, Uganda.
Construction of the 600MW power facility commenced in December 2013 and was expected to be completed by the end of 2018, but delays in land acquisition caused the date of completion to be postponed to December 2019.
The Karuma facility is being built by Uganda Electricity Generation Company (UEGCL) under the preview of the Ministry of Energy and Mineral Development, as well as the Government of Uganda, with an estimated investment of $1.7bn.
UEGCL is also implementing the Karuma interconnection project and the 183MW Isimba hydropower project, which was commissioned in March 2019.
Karuma hydropower plant make-up and design details
The main components of the Karuma hydropower plant include a dam, powerhouse, a surge chamber, pressure shafts, a cable shaft, and tailrace tunnels.
The dam consists of six 238m-long tunnels with a diameter of 7.7m as well as six concrete pressure shafts of 7.7m diameter and lengths ranging between 328.59m and 379.18m. It also includes six tailrace branch tunnels and two tailrace tunnels with a diameter of 12.9m and lengths of 8,690m and 8,707m.
The facility consists of a 200m-long surge chamber with a width of 20m and height of 29m. It is connected to three 2,000 long surge tunnels with a 12m diameter.
The water from Karuma hydropower plant will be diverted to an underground powerhouse consisting of six Francis turbines, which are coupled to six generator units rated 100MW each at 11kV and with a rotation speed of 142.86rpm.
The gross head height of the dam barrage is 70m, while the height of the roller compacted concrete dam structure is 14m and its length is 314m. Design discharge of the plant is 1,128m³/s and its annual energy output is expected to be 4.373 billion kWh.
Power transmission and substation details
The Karuma hydropower plant features an on-site substation housing six generator step-up (GSU) transformer units, which step up the 11kV electricity generated to 400kV. The six GSU transformers will be placed underground in the main transformer cavern, which is located above the underground power station.
Transformers will be connected to the generators through 40m-long bus duct tunnels containing insulated phase buses (IPB) running between the transformer cavern and powerhouse.
Uganda Electricity Transmission Company (UETCL) has carried out the Karuma Interconnection project, which is expected to be completed in 2019, to provide sufficient infrastructure for the transmission of power generated by the facility.
It includes the construction of a 400kV line between Karuma and Kawanda, a 400kV line between Karuma and Olwiyo, and a 132kV line between Karuma and Lira.
China Export and Import Bank (China EXIM Bank) extended a loan equal to 85% of the project cost, while the remaining 15% is financed by the Government of Uganda.
UEGCL selected Switzerland-based engineering and design company, AF-Consult Switzerland, as the project management consultant.
Engineering consulting company Energy Infratech carried out detailed feasibility as well as environment and social impact assessment studies for the hydropower project. The company also designed and prepared tender documents and is performing project supervision.
The engineering, procurement and construction contract for the project was awarded to Sinohydro, a hydropower and constructing company based in China.
Sinohydro subcontracted Alstom (now GE) for supplying turbine generator sets and related equipment for the project.
Transformer units for the project are provided by Shandong Taikai Transformer Company, a company based in China.
Hima Cement, a Uganda-based subsidiary of LafargeHolcim, was subcontracted by Sinohydro to supply cement for the project.
PowerChina Huadong, a subsidiary of Sinohydro, is the main designer, while Entura is providing advisory services.
intec GOPA-International Energy Consultants provided project management and supervision services for the Karuma Interconnection project.