15 February 2012 – For several decades the Stiegler’s Gorge hydroelectric project has been seen by Tanzania as a key component of that country’s hydropower master plan. This plan, completed during the mid-1980s, identified eight potential hydropower projects in the Rufiji Basin.
These potential projects were Ruhidji (685 MW), Mnyera (485 MW) Kihansi (240 MW), Mpanga (165 MW), Iringa (80 MW), Lukose (130 MW), Kilombero (464 MW), and Stiegler’s Gorge (2,100 MW). Only Stiegler’s Gorge was taken to feasibility study stage.
According to this feasibility study a 130 metre gravity arch dam can be constructed in phases at Stiegler’s Gorge. Four phases were proposed, these being sequentially 300 MW, 600 MW, 300 MW and 900 MW phases.
Importantly, the cost of the energy to be produced is estimated to be as low as US2 c/kWh. In the context of East African Power Pool this would give the project and Tanzania a comparative advantage over its neighbours when this project is finally developed.
The project also has advantages in that it would provide flood control downstream where at present a major flood exceeding 2,500 m3/s can occur once every three years. The dam once constructed will have a positive impact on agricultural development downstream where the Rufiji has formed a flood plain.
The dam, once constructed would also create a permanent reservoir with total storage capacity of 34,000 million m3 and this reservoir would be a potential permanent reliable source of water to the city of Dar es Salaam.
The estimated capital cost for the project would be US$2 billion, and at a tariff of US6.5c/kW the project would realise profit some 12 years after commissioning of the first phase. In 2003, the Tanzanian government decided to include Stiegler’s Gorge in its development manifesto. In July 2010, the president of Brazil visited Tanzania and made a promise to implement the Stiegler’s Gorge project.
Considering how long ago the previous feasibility work was undertaken, it is possible that the design of the dam may change, and new studies are likely to be needed. Financing and development options could include EPC, PPP or IPP related options as well as possible integration with other sectors such as water supply, irrigation, tourism, fisheries due to their importance.