contributes significantly to global warming. Coal-fired generation releases more carbon per kilowatt-hour that natural-gas-fired and oil-fired generation. Because of its heavy reliance on cheap, low-grade coal, Eskom is the primary source of greenhouse emissions in South Africa. The coal-fired stations in South Africa were designed to remove dust and other particles from the waste gases but none are fitted with scrubbers to remove oxides of sulfur and nitrogen. This was because the use of scrubbers would increase the cost of electricity substantially. For example, Eskom estimated that if desulphurization plants were to be installed at all of its coal-fired power stations, the cost of electricity would go up by as much as 20 percent.<sup>57</sup> Eskom’s coal-fired power stations are responsible for 66 percent of the 6,000 tons of sulfur dioxide (SO2) pollution that is spewed into South Africa’s atmosphere daily. By comparison, the country's four oil refineries together are responsible for only 1.6 percent.<sup>58</sup> Furthermore, most of Eskom’s power stations are located within a 100 km radius in Mpumalanga and this concentration exacerbates the pollution problem.

In recent years, Eskom has implemented a variety of measures to mitigate the adverse environmental impacts of coal combustion. Through improved technology (e.g. the use of electrostatic precipitators) more than 99 percent of the ash is extracted from the combustion gases before it is released into the atmosphere.<sup>59</sup> The cleansed gas is released through chimney stacks that are tall enough to ensure that the oxides of sulfur and nitrogen are released above the natural inversion layer of the atmosphere (approximately 250 meters above ground) where atmospheric conditions are more favorable for their dispersal and dilution. However, although this reduces ground level concentration of these pollutants, they can combine with moist air and rain at higher levels and cause acid rain in areas far from the source of pollution.

During the past decade, Eskom has made considerable progress in reducing particulate emissions (figure 21). Thus, although between 1999 and 2003 the electricity generated by its coal-fired stations increased by 6,697GWh, total particulate emissions were reduced from 1999 levels. In the last few years, Eskom has consistently met its internal relative performance targets for particulate emissions which during 2005 were reduced to 0.26 kg/MWh sent out.

> 57 The economic and social tradeoff becomes immediately obvious.  At the same cost, electricity could be provided to approximately 240,000 people in township areas.  If, on the other hand, these people without electricity they would have to rely on traditional fuels which can also generate significant levels of pollution.

> 58 Gosling, M. 2005.  “Eskom to Blame for Most Sulphur Pollution”. _Cape Times_ :  August 24, 2005. 59 The operation of electrostatic precipitators is based on the principles of magnetism.  The dust-laden gasses pass through a chamber where the dust particles are ionized by a high voltage negative direct current.  The charged dust particles are removed from the gas stream onto the collecting electrodes. Intermittent blows cause the particles to drop into dust hoppers located below the electrodes. [Eskom. 2005. “Particulate Emission Control at Coal Fired Power Station”.  Generation Communications: GFS 0021, Revision 3 (June 2005)].

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