Carbon sequestration potential of the South Wales Coalfield

This paper presents a preliminary evaluation of the carbon dioxide (CO₂) storage capacity of the unmined coal resources in the South Wales Coalfield, UK. Although a significant amount of the remaining coal may be mineable through traditional techniques, the prospects for opening new mines appear poor. Also, many of the South Wales coal seams are lying unused since they are too deep to be mined economically using conventional methods. There is instead a growing worldwide interest in the potential for releasing the energy value of such coal reserves through alternative technologies – for example through carbon dioxide sequestration with enhanced coal bed methane recovery. In this study, geographical information systems and three-dimensional interpolation are used to obtain the total unmined coal resource below 500 m deep, where the candidate seams for carbon dioxide sequestration are found. The ‘proved’, ‘probable’ and ‘possible’ carbon dioxide storage capacities of the South Wales Coalfield are then obtained using an established methodology. Input parameters are based on statistical distributions, considering a combination of laboratory coal characterisation results and literature review. The results are a proved capacity of 70·1 Mt carbon dioxide, a probable capacity of 104·9 Mt carbon dioxide and a possible capacity of 152·0 Mt carbon dioxide.