Greenhouse gas emissions assessment for electricity generation from coal : an Eskom power station

Abstract: Global Greenhouse Gas (GHG) emissions are projected to increase to 36.7 billion metric tonnes in 2020 due to economic development specifically in developing countries as the demand for energy sources continue to increase. The combustion of fossil fuels for electricity generation is the largest contributor to global CO2 emissions. A total share of CO2 emissions from electricity generation have increased steadily over the past 40 years. Coal-fired power stations generate electricity from converting chemical energy stored in fossil fuels into electrical energy. In the conversion process, carbon contained in the fuel is oxidised releasing GHG emissions and other air pollutants into the atmosphere. GHG emitted during electricity generation are dependent on the characteristics of the fuel used during combustion. In the latest GHG emissions inventory published by the Department of Environment, electricity generation accounted for more than 50 per cent of the total emissions resulting from the combustion of coal. South Africa is dependent on coal for electricity generation mainly due to the abundance of coal reserves and affordability. The main aim of this study was to assess and analyse GHG emissions generated from an Eskom coal-fired power station. This study covered an assessment period of seven years, i.e. 2006 to 2012. The trends for the assessment periods were analysed using methodologies from Eskom and the IPCC guidelines. The results showed that there is a correlation between the amount and type of fuel combusted for electricity generation and GHG emitted. Total fuel (e.g. coal, oil, etc.) combusted at the power station for electricity generation was the main parameter used to estimate GHG emissions. During fossil fuel combustion for electricity generation, GHG are emitted in the form of carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O). In this study, CO2 emissions accounted for the majority of emissions when compared to other gases for the seven year assessment period. Trends for the seven year assessment period varied throughout the years, overall GHG emissions from the coal-fired power station increased by 1.12 per cent from 2006 to 2012. The total GHG emissions measured from the coal-fired power station was 193, 099 GgCO2eq, with coal consumption contributing more than 99 per cent and fuel oil accounting for less than 1.0 per cent of these levels. Specifically, the total CO2, N2O and CH4 emissions measured were 192, 254 GgCO2eq, 804 GgCO2eq and 42 GgCO2eq respectively. This study shows how much of the three GHG (CO2, CH4 and N2O) are emitted during the combustion of coal for the generation of electricity. Furthermore as more coal is burnt to meet the electricity needs of the country, GHG emissions will likely continue to increase in the future hence South Africa should focus its climate change mitigation efforts on this sector.M.Sc. (Environmental Management