Harnessing methane emissions from coal mining

Methane emissions associated with coal-mine ventilation pose a tremendous environmental problem and lead to inadvertent loss of a valuable energy source. The proportion of methane released through underground ventilation is as high as 70% of all the coal-related emissions. Additionally, the CH4 Global Warming Potential is 21 (for a timescale of 100 years), compared with 1 for carbon dioxide. If the heat of combustion of the methane could be usefully employed, this would bring a twofold benefit of avoiding both CH4 release and CO2 emission from the production and use of the fuel thereby displaced. The projects carried out in the Institute of Chemical Engineering, Polish Academy of Sciences explored three major routes for utilizing ventilation air methane (VAM): (1) using VAM as combustion air in conventional boilers, (2) oxidizing VAM in reverse-flow reactors (either catalytic or non-catalytic) to produce heat, (3) enriching VAM (via pressure-swing adsorption or membrane separation) to concentration levels suitable for subsequent use (in, say, reverse-flow reactors). The investigations have now been focused upon homogeneous combustion of VAM in reverse-flow reactors.