Impacts of greenhouse gases from coal power stations on climatic trends in Witbank areas, South Africa

Abstract

Greenhouse gases (GHGs) from coal power station affect the behaviour of climatic parameters such as the temperature, rainfall and evaporation, over a long period of time, hence causing climatic trends. This study focused on investigating the impacts of Greenhouse gases (GHGs) from coal power stations on climatic and hydrological trends in Witbank area. To accomplish this, linear regression (LR) and Mann-Kendall (MK) trend test were used to detect the hydro-climatic trends and their significance. GHG emissions were obtained from Eskom’s sustainability report on the Eskom website. Temperature data for the years 1950- 2000 and 1993-2016 and rainfall data for the years 1925-2000 and 1993-2016 were used. Double Mass Analysis (DMA) was used to check the homogeneity and consistency of temperature and rainfall data from South African Weather Services (SAWS) station with the Lynch database and Water Research Commission (WRC) data. Data was patched and extended using LR where necessary. Trends in temperature, precipitation and flow were assessed using MK trend test and LR based on monthly, seasonal, and annual scales. GHG emissions were compared with the hydro-climatic data over time in order to detect the impacts of GHG emissions on temperature, rainfall and streamflow. The MK results indicated that GHG emissions had some impacts on temperature with statistically significant increase in annual, monthly and seasonal time scales for the period 1950-2016. LR also produced the same results for annual temperature. Monthly and seasonal temperature could not be produced with the LR method because of data gaps. The MK and LR models produced similar results, indicating that there was a non-significant increase in temperature before coal power stations were introduced (1950-1974) and a significant increase in temperature after the commissioning of coal power stations (1975-2016). MK and LR also produced the same results for annual rainfall data, indicating that there was a significant increase in rainfall before coal power stations were introduced (1925-1974) and a non-significant increase after the commissioning of coal power stations (1975-2016). For monthly time scales MK and LR indicated increasing and decreasing trends before and after coal power stations were introduced. MK and LR results for streamflow stations B2H004 and B2H007 showed similar results indicating non-significant increase in annual and seasonal streamflow, but differed in monthly streamflow where MK showed significant increases whilst LR showed non-significant trends. The study concluded that GHGs from coal power stations had significant impacts on the hydro-climatic trends in Witbank area. GHGs from coal power stations caused significant increase in temperature as temperature increased by 3.7°C after coal power stations were introduced, whereas temperature had increased by 1.7 °C. It is recommened that more research should be done on alternative sources of energy such as wind and solar energy to check their suitability and applicability in South Africa.