Steady state CFD modelling of carbon dioxide release and methananogenesis in coal heaps

Abstract

The Kyoto Protocol and its related instruments have increased awareness of the phenomenon of global warming. The two main so-called greenhouse gases deemed to cause this effect have been identified as CO2 and CH4. Other greenhouse gases include N2O, hydrofluorocarbons, perfluorocarbons and SF6, although these occur to a lesser extent than the former two. This has led to efforts to quantify and curb the release of these two main constituent greenhouse gases. CO2 is released through various biological, natural and industrial processes and the burning of fossil fuels. Methane is also classified as a fossil fuel leading to CO2 release but can also be spontaneously released to the atmosphere from the earth’s crust due to release of trapped methane or methanogenic processes. The global warming potential of methane is 21 times greater than that of CO2. The coal stockpiles and dumps from mining activities are difficult to control sources of great amounts of both CO2 and CH4 due to spontaneous oxidation. The aim of this study is to highlight the capability of CFD in capturing the chemical kinetics leading to the formation of both CO2 and CH4 in coal heaps.