Cahora Bassa Technical Assistance and Monitoring Systems Project

On November 27, 2007 the Governments of Mozambique (GoM) and Portugal (GoP) signed agreements transferring the majority of ownership and control of Hidroeléctrica de Cahora Bassa (HCB) from GoP to GoM. MHI was selected by HCB as its technical partner to provide operational support and monitoring.

Profile

Cahora Bassa is the largest hydroelectric scheme in Southern Africa. It was conceived in the 1960s as a bilateral project between the governments of Portugal and South Africa and was formally launched by an international treaty signed in September 1969.

The intention was to build a project that would, in the words of the treaty, supply electricity “… for use in the territories of Mozambique and South Africa and possibly other countries.” Construction began in 1970 and power was first delivered to South Africa in May 1975, followed by the creation of the HCB in June 1975.

The Cahora Bassa Hydroelectric Dam, S.A. (HCB) is a national company largely owned by the Mozambican state with some capital investment by the Portuguese State. The facility is located in the Cahora Bassa district in the western area of Tete province and has the primary function of producing and transmitting electricity. The company supplies most of the electricity used in Mozambique and is the anchor for the Mozambican government’s development of the rural electrification project.

The Dam and Powerhouse

The double arch curvature Cahora Bassa Hydro-electric dam is one of the largest hydro-electric dams in Africa. The dam is physically 171m high, 303m wide at the crest, 23m thick at the base and 4m thick at the crown, and boasts 8 mid-level radial spillway gates, one surface gate, and a total discharge capacity of 14,000 m3/s.

The underground south bank powerhouse has 5 turbo-generator sets of 415 MW each with total station capacity of 2,075 MW, and maximum turbine flows of 2,250 m3/s.

Characteristics of the reservoir include a maximum volume of 65 x 109 m3; total available volume of 52 x 109 m3; approximately 270 km in length and 30 km in width; and maximum inundation area of 2,660 km2

The Project

Technical assistance provided by MHI covers all aspects pertaining to the operation, maintenance, and capital improvements of the Dam structure, the Power House, the HVDC Converter Station, and the HVDC /AC transmission lines.

MHI has thus far been involved in overseeing and assessing that operating, capital budget, and major capital expenditure programs are in accordance with Good Industry Practice.

MHI has been successful in developing key performance indicators (KPIs) and resolutions to technical operating inefficiencies including the rehabilitation of the HVDC scheme.

Technical support has also included quarterly monitoring of budget performance (Revenue, Capex and Opex); technical performance (generation, conversion and transmission); major engineering projects, including spillway gates redesign and refurbishment, Convertor Station Rehabilitation, DC transmission line rehabilitation and Cahora Bassa North Bank Project; health, safety and environmental performance; human resources management (training, recruitment and succession planning); and reservoir management and dam safety.

Furthermore, MHI has assisted in the design and development of an Environmental Management System (EMS) consistent with ISO 14001 guidelines, staff recruitment and retention strategies, and managerial and technical training programs.

For the past three years MHI has provided HCB with a full-time resident Operations and Maintenance advisor to provide on-site assistance to HCB’s Management Team.

Through the dedication and commitment of HCB management and staff and the assistance of MHI, many of HCB’s KPIs compare favorably to the best in class utilities worldwide.