Hydroelectric energy
Author: Wim Jonker Klunne / hydropower4africa
( Article Type: Explanation )
The first images that come to mind when thinking about hydropower are the large dams like Kariba and Cabora Bassa or perhaps the Gariep dam. Whilst hydropower from these few large dams contributes only a very small fraction to our total energy supply, there is far wider potential for the development of small scale hydropower plants throughout South Africa. Small scale hydropower refers to installations with an installed capacity of less than 10 MW. Within the range of small hydro, distinction can be made between mini hydro (often limited to an installed capacity of maximum 1 MW), micro hydro (below 300 or 100 kW depending on the definition) and picohydro (below 20, 10 or 5 kW), each with its own specific technical characteristics. Micro and pico hydro installations are mostly found in rural areas for energy provision to isolated communities where the national electricity grid is not available, whereas mini hydro tends to be grid connected.
Although not very well documented, small scale hydropower used to play an important role in the provision of energy to urban and rural areas of South Africa.
The first provision of electricity to cities like Cape Town and Pretoria was based on small scale hydro, while also smaller towns started local distribution of electricity through isolated grids powered by small hydro stations. The gold mines at Pilgrims’ Rest, for example, were powered by two 6 kW hydro turbines as early as 1892, complemented by a 45 kW turbine in 1894 to power the first electrical railway. However, with the expansion of the national electricity grid and the cheap, coal-generated power supplied through this grid, large numbers of systems were decommissioned. A typical example is the Sabie Gorge hydro station with three 450 kW turbines, commissioned in 1928 to serve the town of Sabie in Mpumalanga, which was closed in 1964 after the area was connected to the national ESKOM grid. The South African Renewable Energy Database, as developed by the CSIR, did investigate the available renewable energy resources in the country, including the potential for hydropower.
The primary objective of this project was to identify the commercially viable opportunities for rural electrification in the Eastern Cape Province of South Africa using wind, hydro and biomass powered energy systems. In the ‘Baseline study on Hydropower in South Africa’, which was developed as part of the Danish support to the South African Department of Minerals and Energy, Barta (2002) investigates the installed capacities of hydropower in South Africa and the potential for new developments. He concludes that twice the installed capacity of the present installed hydropower capacity below 10 MW can be developed in the rural areas of the Eastern Cape, Free State, KwaZulu Natal and Mpumalanga.
The recent opening of the Bethlehem hydropower plants, the first ones opened in more than 2 decades, have proven that small hydro developments are possible in South Africa. In a submission to the IRP process, the SESSA hydro interest group presented projections of 272 MW of hydropower by 2016, another 400 MW by 2020 and further 1 100 MW to be installed by 2030. Although small in size and not as visible as large hydro, small hydropower will be able to make a significant, positive contribution to energy supply in South Africa!
