Suitability of Victorian brown coal for CO2 sequestration: an experimental overview on effect of moisture on CO2/CH4 exchange

Brown coal seams located in Victoria, Australia are possible sinks for CO2 storage. However, the higher moisture contents (55-60%) present in these coal seams may affect the CO2/CH4 exchange capacities and was investigated in this study as the main objective. A series of isothermal (40⁰C) sorption tests were carried out on brown coal specimens for different moisture contents (dry, 20%, 40% and 60%) and both CO2 and CH4 was flooded up to 10.5 MPa. The data was then evaluated by fitting to the modified Dubinin-Radushkevich (DR) model. The CO2 and CH4 capacities of the brown coal was affected by the presence of moisture. However, both sorbates displayed some critical moisture levels and afterward, sorption capacity was not affected. The net heat of adsorption pronounced a marginal decrease on addition of moisture for both sorbates. The current findings permit further investigations on swelling effect on wet brown coal for long-term CO2 sorption capacities.