GAW Report No. 205 - IGAC Project

CHAPTER 2 - AFRICAranging from waste incineration (including medical, toxic, animal and other waste types), petroleumrefining, inorganic and organic chemical processing (e.g. carbon black processes), mineral productindustries (e.g. brickworks), cement manufacturing, coal conversion (e.g. Sasol oil from coal plantsat Sasolburg and Secunda), glass manufacture and metallurgical industries. Note that the Sasolprocess of coal gasification in the production of synthetic liquid fuels from gas is a relatively uniqueprocess, whose emissions are expected to be very high.Fuel other than electricity, used for household for cooking, lighting and/or space heatingpurposes primarily include: coal, wood, LPG, paraffin and candles. Waste material, including oldshoes and tires, is also burned by households unable to afford other fuel carriers. In rural areas,some households burn animal dung to meet their energy, heating and cooking needs. Continueduse of coal and wood by a large section of the population in South Africa is a cause of concernwith regard to air pollution and health risk potentials. These fuels continue to be used for primarilytwo reasons: (i) rapid urbanization and growth of informal settlements (ii) Coal is readily availableand inexpensively in Gauteng and Mpumalanga. Given the availability of coal and relatively lowtemperatures experienced during winter months, coal consumption is high in these regions. Woodis burned in place of coal in coastal regions including Cape Town and Ethekwini. Household fuelburning tends to peak during early morning and evening at which times the atmosphere ischaracterised by limited mixing depths and stable conditions favourable to stagnation of pollution[Engelbrecht et al., 2000]. Due to emissions in a confined space (indoor pollution) and due towinter maximum uses being associated with minimum atmospheric dispersion, domestic fuelburning emissions have a greater potential impact on air quality as compared to equivalentemissions from, for example, industrial sources.Focus on coal use in the different sectors shows that 2% is for industry, 2% for thedomestic sector (producing 25% of the emissions), 43% for electricity, 30% for export and 21% forcoal liquefaction (synthetic fuel production).Diesel and petrol (including leaded and unleaded petrol) represent the main fuels used byvehicles. Note that reductions in ambient lead concentrations (consequently in blood lead levels ofchildren) have been observed. This could be due to the introduction of unleaded fuels, with leadedfuel phased out in January 2006. Other mobile source uses a variety of fuels, e.g. aircraft mainlyuse jet fuel, ship engines typically use marine diesel oil and non-electrified trains use primarilydiesel and coal.Local inventoriesSince 1990, a national effort has taken place to develop local emission inventories. Certainmetropolitan areas have emission inventories for common pollutants such as SO 2 , NO X , CO, CO 2 ,hydrocarbons and particulates (TSP or PM 10 ).In Johannesburg, combustion-related emission sources have been identified and effortshave been made to quantify some of these sources, but no exhaustive emission inventory currentlyexists. For example, in the National emission inventory database (1994), emission inventories forcoal power plants in the area are available. Domestic coal combustion emission inventories havebeen developed from different assessments and measurements [Scorgie et al., 2003a], giving amean total of 3878 tons/yr for PM 10 . Emissions data for the transport sector only included dieselfuel with 1625 tons/yr of PM 10 . Data is also available for spatial emission based on road density,industry and power plant location maps.In 1995 an emissions inventory for municipal areas in the Vaal Triangle was established[Van Nierop, 1995]. The emissions inventory includes industrial, domestic, vehicular and powerplant sectors. In parallel, a few experiments took place on domestic fuel emissions forcharacterization. During the winter of 1997, Engelbrecht et al. [1998; 2002] and Terblanche[1995b; 1998] found 62% of PM25 came from domestic burning, 14% from biomass burning, 11%from dust and only a minor contribution from power plants and vehicles. More interestingly, twotypes of coal were studied: D grade coal (low quality usually used) and low smoke coal (as analternative source of energy). The results showed a 25% reduction of particulate emissions when43