Making the right connection
South AfricaÔÇÖs state-owned utility company Eskom has been pulling out all the stops to keep up with the countryÔÇÖs rapidly expanding demand for electricity. Gay Sutton reviews the companyÔÇÖs ambitious construction programme.
South Africa has gone through a period of transformation over the past 15 years. Incorporation of the black community into the powerhouse of business, strong economic growth, rapid industrialisation and an improvement in living standards have all imposed strains on the countryÔÇÖs existing infrastructure. Demand for power in South Africa, particularly in recent years, has been growing at a frightening rate. And in spite of the steps taken to increase capacity, demand outstripped capacity last year and blackouts became a fact of life around the country.
Power generation and distribution company Eskom, which was established way back in 1923, supplies approximately 95 per cent of South AfricaÔÇÖs electricityÔÇöwhich equates to around 45 per cent of the electricity generated across the whole of Africa. In recent years, the company has been pulling out all the stops to increase its power generation capacity and to improve the nationÔÇÖs distribution infrastructure in order to live up to the GovernmentÔÇÖs aim of supplying all homes with electricity.
An ambitious programme of construction was initiated some four years ago, with the aim of delivering more than 14,600 megawatts of additional power by 2017, and to double the current capacity by 2028. The first phase of the programme includes the construction of three new power stations utilising the latest technology.
The first of these has been named Medupi, which means ÔÇÿrain that soaks parched lands, giving economic reliefÔÇÖ. Not only will it be EskomÔÇÖs first new coal-fired power station in 20 years, it will also be the fourth largest coal plant in the world and the largest dry-cooled power station to be built globally. Highly advanced, the boilers at the new power station will be using super critical plant technology, meaning they will operate at higher temperatures and pressures than previous boilers, therefore performing more efficiently and consuming less water and coal.
The site for this prestigious project was carefully chosen. Thorough screening and feasibility studies of a number of sites identified a former farm at Lephalale, Limpopo Province, as the most suitable location. A whole range of criteria was assessed, including the availability of primary resources, the ability to connect to the Eskom grid, environmental acceptability and cost of production. Lephalale benefits by being close to the existing Matimba power station, which already has access to the grid, and enjoys close proximity to a competitively priced primary source of coal.
Having received the licence to build in 2006, construction activities commenced in May 2007. The first of the six units of the power plant is scheduled for commissioning during the first half of 2012 and the remaining five units will follow at six- to eight-month intervals. Once fully commissioned, the plant will contribute 4,764 megawatts to the grid and is expected to have an operational life span of at least 50 years.
Construction of EskomÔÇÖs second most advanced coal-fired power station is now under way at Delmas, Mpumalanga Province, and ground was broken on the project in 2007. Named Kusile, the plant has been sited close to the existing Kendal power station, and contracts have been agreed with Anglo Coal South Africa to supply coal from a new colliery at New Largo, close to the power station.
Kusile will be the first power station in South Africa to be fitted with flue gas desulphurisation, which is designed to remove oxides of sulphur (SOx) from the exhaust flue gases. This state-of-the-art emission reduction technology consists of a totally integrated chemical plant that uses limestone as feedstock and produces gypsumÔÇöan ingredient used in the manufacture of dry walls and ceilingsÔÇöas a by-product.
The first of KusileÔÇÖs units should come into commercial operation in 2013, and the remaining five will be commissioned at nine-month intervals, the last one coming on line in 2017. When fully up and running, the power station will have an installed nominal capacity of 4,800 megawatts of base load power.
The final power station to be constructed in this phase of development is a pumped storage scheme called Ingula, the concept for which dates back to the 1980s. The site for the power station was again chosen carefully from a total of 90 possible locations. The requirements were that it had to have two suitable dams relatively close to each other but at significantly different altitudes, with suitable geology and a readily available water supply. The location eventually chosen was north-east of Van ReenenÔÇÖs Pass on the boundary between Free State and KwaZulu Natal.
The Ingula pumped storage scheme consists of two dams with the capacity to carry 22 million cubic metres of water each. The dams are 6.6 kilometres apart, one located higher than the other, and the two will be linked by four underground waterways running through an underground powerhouse that will be fitted out with four pump turbines.
The idea is that when demand for power peaks and exceeds the base load supply, water can be released from the upper dam through the turbines to the lower dam, generating electricity. Then when demand is low, the turbines are used to pump the water from the lower dam back up to the upper damÔÇöessentially storing energy for future use.
Work is now well underway on the project. Construction of the infrastructure began in January 2007, while the main underground work began in September 2008. The power station should come on line in 2013, with one unit being commissioned each quarter of that year.
In all three of these projects, considerable attention has been paid to protecting the environment. Specifically for the Ingula project, Eskom established a partnership with two non-governmental organisations, BirdLife South Africa and Middelpunt Wetland Trust, to provide a forum for discussion and advice on environmental issues. The partnership has been meeting regularly for the past five-and-a-half years. To extend participation to other organisations interested in environmental aspects of the pumped storage scheme, the Ingula Partnership created a working committee with participation from, among others, the Department of Agriculture, the KwaZulu Natal and Free State Provincial Environmental Departments, and the Ekangala Grassland Trust. The area around Ingula is a valuable source of water for the Highveld and also a habitat for a variety of plants, birds and animals. Among the wildlife that can be spotted in the area are the wattled crane, one of South AfricaÔÇÖs five most endangered birds, and the threatened oribi, a small and very graceful antelope.
Eskom has therefore decided to manage the region as a conservation area, and in cooperation with land owners in the district, it will be creating a larger conservation area to protect the moist grasslands of eastern Free State and northern KwaZulu Natal. A key part of the programme will be the creation of a network of walking and hiking trails, while other eco-tourism attractions such as river trails, birding and cycling will be investigated.
On both the Medupi and Kusile sites, care has been taken to move and replant trees that would be affected by ground clearance, and to relocate wildlife. At Medupi, for example, a beautiful visual beacon on the site was an ancient baobab tree believed to be several hundred years old. A lengthy process was initiated to relocate the tree to the entrance of the power station where it will continue to be a local landmark. Meanwhile, at Kusile, two heritage sites were preserved and some 205 graves were relocated.
An extensive programme to improve the transmission line network has also been underway for the past four years. During that time, some 1,962 kilometres of high-voltage transmission lines have been installed and a new ultra high-voltage line to the Cape is under construction. Meanwhile, refurbishment of the Apollo substation is expected to increase the availability of the Cahora Bassa/Apollo DC interconnection, and a total of 10 new transformers have been installed.
These major construction projects are part of a long-term investment that will enable Eskom to meet South AfricaÔÇÖs power needs in the future. However, steps had to be taken urgently to provide extra capacity to relieve pressure on the grid and to do this, the company has done several things. It has been working to bring back into service three coal-fired power stations which had been mothballed in the late 1980s/early 1990s. The Camden power station is now back on line and delivering 1,440 megawatts of power to the grid, while the Grootvlei and Komati stations are currently in the process of being re-commissioned. In addition, two new open cycle gas turbine stations were commissioned in October 2007 and have subsequently been further expanded: Ankerlig can now deliver up to 1,327 megawatts to the grid when required, and Gourikwa can deliver up to 740 megawatts.
Power is generated in South Africa by a variety of methods. However, the majority of the base-load powerÔÇöthat which provides the steady day-to-day demandÔÇöis currently generated by coal-fired power stations which operate 24 hours a day. When the three mothballed power stations are fully operational again, they will boost coal-fired generation nominal capacity by some 3,720 megawatts, bringing the companyÔÇÖs total coal-fired power generation nominal capacity to 37,773 megawatts. This will bring the number of operational coal-fired power stations to 13. Eleven of them are located in Mpumalanga Province, one in Free State and one in Northern Province. Interestingly, Eskom also operates the only nuclear power station in Africa. Located in the Western Cape, the Koeberg plant contributes 1,800 megawatts to the base load power supplied to the grid.┬á
Capacity is then boosted by two hydroelectric power stations and two hydro pumped storage schemes, which kick into production whenever there is a peak in demand which exceeds the normal capacity, and together they can contribute an extra 2,000 megawatts. And finally, four quick reaction gas turbine power stations producing a total of 2,409 megawatts can be brought into action during extreme emergenciesÔÇöGourikwa and Ankerlig being two of these. However, gas turbine power stations have very high operating costs, so these power stations are generally used only as a last resort.
Eskom has not remained immune to the difficult global economic situation, and the company has had to postpone several projects that were to have been included in this first phase of expansion. One of the casualties was a proposed 100 megawatt wind farm in the Northern Cape. However, the company is fully committed to increasing its capacity, supporting South AfricaÔÇÖs growth in the future and is well on the way to doubling the current 40,000 megawatt capacity to 80,000 megawatts by 2028.