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Inga: Promise

MAY 18, 2004 Business In Africa Online

The development of Inga-3 is now associated with the Western Power Corridor (WESTCOR), a joint venture company registered in Botswana. WESTCOR aims to transmit power from Inga-3 in the DRC to South Africa via Angola, Namibia and Botswana. Once the WESTCOR Joint Venture Company is formed, equal equity contributions from the five national utilities and their chosen partners will make up the equity portion and security package for the debt portion of the project financing. International financiers will be encouraged to participate and to take up debt financing. Considerable support is also expected via the NEPAD initiative. There are three main components in the implementation of the WESTCOR project:

  • The development of the Inga-3 power station is estimated to cost US$3.74 billion
  • Two 1,500MW converter stations will be constructed at a basic cost of approximately US$421 million each, totalling US$842 million. Upgrades for the two existing stations along the lines will be included in the HVDC installation cost.
  • Converter stations - HVDC transmission lines: The two South African termination points are 3,000 to 3,500 km from Inga-3. The total estimated cost for the transmission lines, including the terminations in South Africa, is US$652 million.

Inga site characteristics

Inga site is situated at a latitude of almost six degrees south and 14 degrees east in the DRC. It is about 150km upstream of the mouth of the Congo River and 225km downstream from Kinshasa. The Congo River, with an average flow rate of 42,000 cubic metres per second, is the second largest river in the world after the Amazon. Among the big rivers of the world, it is the only one that has a significant slope in its lower course. For instance, in a distance of 15km, the natural difference in height is 102 metres. This series of rapids makes the Inga site the biggest source of hydro power in the world at a single point; the unbridled energy passing the point amounts to approximately 370 billion kWh per annum. Inga's yearly minimum flow rate is not less than half the annual maximum flow rate and this makes the river stable and suitable for power generation. The historical minimum flow rate was recorded in 1905 and was 21,400 cubic metres per second. The historical maximum flow rate, 84,400 cubic metres per second, was recorded in 1961.

Development of the Inga site

The overall development of the site foresaw four stages grouped into two phases. The first stage was the use of the Nkokolo valley to its maximum potential, while the second phase was the construction of the Grand Inga. The Nkokolo valley scheme does not require building a dam over the whole river. It uses a disused river bed that is closed off by the Shongo dam at the lower end. This gives a head of 60 metres to a part of the water diverted from the river at a point 8 km upstream. The scheme involves three stages of development:

  • Inga-1 Power Station (commissioned in 1972)
  • Inga-2 Power Station (commissioned in 1982)
  • Inga-3 Power Station (planned). The development of Inga-3 is now associated with the Western Power Corridor (WESTCOR) and will be described in detail later in this article.

The Grand Inga scheme involves building a dam across the whole river so as to divert all the water into the adjacent Bundi valley, and the total flow rate of 26,400 cubic metres per second at its minimum can be used under a head of 150 metres to generate 39,000MW in total (52 machines at 750MW each).

Export potential

Six power export corridors have been identified for power transmission from the Inga site as follows; western, northwestern, northern, northeastern, eastern, and southern (Figure 3). The existing Inga-Kolwezi HVDC and the AC network linking it to Zambia, Zimbabwe, Botswana, and South Africa forms the southeastern corridor. The western corridor will link Inga to West Africa, to supply the potentially large market in Nigeria, plus imports to the rest of West Africa. The northern and northwestern corridors will serve Morocco, Algeria, Tunisia and Libya.

Planned rehabilitation of Inga

Existing power stations

The characteristics of the existing power stations (Inga-1 and Inga-2) are given in Table 1. The Societé Nationale d' Electricité (SNEL) of the DRC owns and operates the two existing power stations, Inga-1 and Inga-2, with a combined output of 1,770MW.

Characteristics of the existing power stations

Inga-1 Inga-2
Year of commissioning 1972 1982
Water head [metres] 50 58
Turbine flow [cubic metres per second] 780 2,800
Number of machines 6 8
Installed Capacity [MW] 351 1,424
Expected Production [TWh/Year] 2.4 10.4

Planned expansion

Inga-3 is the next phase of the development of the Inga site, with a projected output of 3,500MW. The final phase of the development will be the Grand Inga, with a potential rated output of 39,000 MW.

Characteristics of the planned expansion

Inga-3 (WESTCOR) Grand Inga
Water head [m] 6,300 26,400
Turbine flow [cubic metres per second] 50 58
Number of machines [MW] 3,500 39,000
Expected Production [TWh/Year] 23.5 288.0

The western power corridor

The Western Power Corridor project (WESTCOR) is intended to exploit the environmentally friendly, renewable, hydroelectric energy of the Inga rapids site in the DRC. Load growth in the southern networks has outstripped expectations as a result of energy-intensive investments taking advantage of the excellent quality of supply available in the SADC region at internationally competitive prices. Studies have shown that additional generating capacity will need to be in regular commercial service in the southern networks of the SAPP by as early as 2007.

In addition, the Empresa Nacional De Electricidade (ENE) of Angola reported that the hydroelectric potential of the Cuanza Basin in northern Angola is approximately 6,000MW. ENE expressed interest in developing this resource and exporting the energy to WESTCOR and other customers in SAPP. An additional 2,500MW can be potentially captured from gas presently flared off in the northern Angolan oilfields. Elf Aquitaine and GEC Alsthom did a preliminary scoping study during the mid-1990s to export this available energy to South Africa.

The WESTCOR Joint Venture Company

The WESTCOR Steering Committee was formed under the auspices of the SAPP to initiate studies determining the viability of the Western Power Corridor with the source at Inga-3. The WESTCOR Joint Venture Company was registered in Botswana to fund the engineering and financial studies, and to build, own, and operate the infrastructure, should the project prove to be viable. Each of the five participating utilities contributed $100,000 as start-up capital to fund the first phase of development.

Five utilities are participating in the project. Each utility is represented on the Steering Committee and will own 20 per cent of the share capital of the proposed new joint venture company. The utilities are:

  • NamPower, power utility company of Namibia
  • Eskom, power utility company of South Africa
  • Empresa Nacional De Electricidade (ENE), power utility company of Angola
  • Societé Nationale d' Electricité (SNEL), power utility company of the DRC
  • Botswana Power Corporation (BPC), power utility company of Botswana.

Environmental concerns

A complete Environmental Impact Assessment (EIA) study is scheduled in the immediate future for the twin HVDC lines serving as the interconnector through DRC, Angola, Namibia, Botswana and South Africa. Preliminary surveys, however, have not identified any evident environmental risks in the development of the project. Thus, it is anticipated that any environmental concerns found in the study will be easily resolved. Where the environmental impact of Inga-3 is concerned, the Congo river flow does not show seasonal variations to the extent of other rivers in the Southern African region, and is therefore sufficiently reliable to enable the Inga site to be developed on a run-of-river basis. The lack of variation in river flow is due to the catchments area that straddles the equator, and the seasonal rainfall patterns in the northern and southern areas that are contra cyclic to the river flow. This eliminates the need for a costly large storage dam to compensate for seasonal variations in river flow. In addition, eliminating the need to flood large areas significantly reduces the environmental impact. As a result, energy from Inga-3 would qualify as green energy in terms of the Kyoto Protocol on global warming, and the sale of carbon credits to developed countries could become an additional source of revenue for WESTCOR.

WESTCOR customers

The primary customers of WESTCOR are expected to be the SAPP member utilities. With Inga-3 producing 3,500MW for WESTCOR, distribution along the transmission lines has been predicted according to the estimated demand within each of the five participating countries. Due to the cheap energy in Southern Africa the WESTCOR project will attract industry requiring high power consumption. Immediate examples are those of the Hindalco smelter, which will relocate from India to Walvis Bay in Namibia, as well as the Al smelter for BHP Billiton in Coega, South Africa.

This is a presentation by Mr. B. J. Mbuere ua Mbuere from Nampower and Dr. Lawrence Musaba from the SAPP Zimbabwe, presented at the Power Generation Conference


Updated: 2003/07/28