The R200-million ugrade of the Acacia substation, in Cape Town, which forms part of State-owned power utility Eskom’s R426-billion capacity expansion programme, is expected to be complete by May 2010. The upgrade will ensure reliable electricity supply during the FIFA soccer World Cup and beyond, says Eskom.
The required power generation from the Acacia substation exceeded its firm capacity (guaranteed power supply) of 500 MVA. The maximum load of 694 MVA, measured in 2006, at the substation, exceeded the transformer firm capacity by 194 MVA. Acacia’s 500-MVA firm capacity was calculated from the existing two 500-MVA 400/132-kV transformers.
The substation’s upgrade includes the extension of a 132-kV transformer to accommodate two feeder bays and one transformer bay and the installation of a third 500-MVA 400/132-kV transformer.
Meanwhile, the utility’s five-year capacity expansion programme aims to meet South Africa’s rising electricity demand. Eskom has allocated 13% of the R426-billion approved capacity expansion budget to upgrading South Africa’s transmission network. A further 73% has been allocated to electricity generation projects, while the balance of the budget will fund improvements to the distribution network and efforts to diversify South Africa’s energy sources, says Eskom.
Part of the electricity tarriff increases, 24,8% from April 1, 25,8% from April 1, 2011, and 25,9% from April 1, 2012, which were recently granted to Eskom by the National Energy Regulator of South Africa (Nersa) will assist in funding the utility’s R426-billion capacity expansion programme.
The current budget for the capacity expansion programme should last until March 2013, but it is expected to grow to more than R1-trillion by 2025.
Meanwhile, the upgrade of the Johannesburg North substation should be complete by October 2010. The utility reports that this upgrade involves the commissioning of four transformers and is progressing, as three transformers have already been commissioned.
Other transmission projects include the 400-kV strengthening of the Nelson Mandela Bay area, as wel as the 275-kV and 400-kV strengthening in the Polokwane area that is expected to be complete by the end of 2010. The 765-kV strengthening (operated at 400 kV) of the Empangeni area is expected to be complete by the end of 2011. While the 765-kV project from the Zeus substation, in Mpumalanga province, to the Omega substation, near the Koeberg nuclear power station, in the Western Cape, covering about 1 450 km, is expected to be complete by mid-2012. The work involved includes the upgrading of substations and the installation of new transformers.
The Limpopo-province-based Medupi power station 400-kV integration and the 400-kV integration of the Ingula power station, which borders the Free State and Kwazulu-Natal, are expected to be complete by the end of 2013. Further, the 400-kV network into Mthatha, in the Eastern Cape, is scheduled to be complete by mid-2012.
Eskom says that other major transmission projects completed in 2009 include a new 400-kV transmission line and three new substations to strengthen the supply to the Platinum basin, a collective name for the platinum-and-chrome-mining industry in Rustenburg, Brits and Polokwane.
“Work on the Vaal strengthening scheme, which involves the upgrading of eight substations in the West Rand and Vaal areas, is also progressing, with four of the stations already more than 50% complete,” the company reports.
The progress on these projects has been generally good, says Eskom; however, owing to financial constraints, certain project plans have been put on hold for six to nine months. Other major constraints have been the lack of access to sites, because of problems with landowners and ongoing network outage cancellations, as well as unusually wet weather conditions that prevent contractors from working.
Electricity Supply to Neighbouring African Countries
Eskom currently sells and imports electricity to and from neighbouring African countries. It has long-term agreements with some industrial end-users who provide firm power. The agreements with African regional utilities are a mixture of firm agreements and nonfirm agreements.
Eskom has agreements with Namibia, Swaziland, Lesotho, Botswana and Mozambique. Zimbabwe and Zambia are also trading partners, but, because of the nature of the agreements and the energy constraints in South Africa, Eskom does not currently sell to them.
“The majority of agreements have escalation clauses linked to the tariff increases promulgated by Nersa. These countries will, therefore, also experience tariff increases in line with South African customers,” Eskom’s media desk confirmed with Engineering News.
The company exports power to neighbouring countries and imports from them as a member of the Southern African Power Pool, which was founded in 1995. Eskom says that neighbouring countries have a relatively small demand for electricity, which makes it uneconomic to invest in generation capacity. Some neighbours rely on imported power to supplement between 50% and 80% of their electricity needs.
“Such situations cannot be quickly reversed and the sudden removal of such levels of power would have a crippling effect on these countries’ economies, with a knock-on effect for the regional economy, including South Africa.”
Eskom explains that many of these countries have considerable coal resources or hydroelectric potential and, hence, present attractive electricity-generation opportunities for the future. As South Africa’s domestic electricity demand grows and production costs increase, there is growing potential for electricity imports into the country, par- ticularly from hydrostations as renewable energy will help reduce South Africa’s overall dependence on coal.
The company says that the issue of power exports has been of concern to South African customers, particularly with the recent power supply constraints. Therefore, power shortages have prompted Eskom to modify its role in order to increase imports and decrease exports.
“However, because of the relative size of the level of net exports, ceasing exports and losing imports would not result in a material difference in the current energy situation in South Africa. The short-term response has been to maintain purchases from our neighbouring States and reduce sales as much as possible,” the company states.