Verification of the ADMS 4 Air Quality Model in determining the SO2 dispersion during the 2006 and 2007 winter over Elandsfontein, South Africa

Abstract

ADMS 4 is a relatively new generation air quality dispersion model program written by Cambridge Environmental Research Consultants in the UK and used to verify datasets in the USA on several types of plants, in various settings across the country. Typical results indicate an approximate 20% under prediction. It was decided to use this model to verify SO2 emissions typical of the Eastern Highveld, which has several varying industries emitting SO2 gases in the region. Two datasets were identified with complete data recorded, supplied by ESKOM as measured at their Elandsfontein site for the winter periods mid 2006 and 2007. The meteorological data recorded at Elandsfontein was used for the model and the SO2 predicted emissions by ADMS 4 then compared to the actual measured SO2 emissions at the monitoring site, to determine the efficiency level of ADMS 4. Efficiency levels of 42% for the 2006 dataset and 58% for the 2007 dataset were achieved. The high level of under prediction is ascribed to the influence of the local petrochemical refinery (SASOL) as well as the local steelworks plants also emitting SO2 gas, but was not entered into the model database for evaluation in conjunction with the power stations’ emissions data.