Alvi, Syed Muhammad Hussain Turab
Rapid industrialization and fossil fuel consumption are major contributors to greenhouse gas (GHG) emissions and ensuing global climate change. The concentration of CO2, a GHG, in Earth’s atmosphere has reached unprecedented levels. Contemporary studies assert that geological storage of CO2 is among the most effective ways to curb GHG emissions to the atmosphere, with the aim of mitigating global climate change. In this study we experimentally investigate CO2 adsorption on three distinct Turkish lignite coals—namely, Çankırı, Elazığ–Sivrice, and Amasya–Merzifon. The volumetric method is employed to ascertain the CO2 adsorption capacity at a constant temperature of 313.15 K (40 oC) and incremental pressures up to 85 bars. A compression setup is employed for compressing CO2 gas above 60 bars, to achieve supercritical state. Data acquired from experiments is used to develop excess adsorption isotherms through Gibbs excess adsorption equation, facilitating observation of the interaction between CO2 and the coal samples. The study utilizes four adsorption models, (1) Langmuir modified, (2) Langmuir modified +k, (3) D-R modified, and (4) D-R modified +k, to fit the experimental results. The function of correction term ‘k’ is to account for and mitigate various measurement uncertainties. The Average Relative Error (ARE%) function is harnessed to compare model performances. All the sorption models fit the data with an ARE of less than ±9 %. Notably, the D-R modified model demonstrates the best fit. Furthermore, it has been observed that the drying of the samples before the experiment leads to moisture loss, resulting in visible shrinkage within the range of approximately 4 % - 9 % by volume. Finally, the storage potential of the three coal seams is approximated using seam volume data from literature. Elazığ–Sivrice exhibits a maximum CO2 storage potential of 6.28 Mt despite its relatively modest reserves. Çankırı follows with a storage capacity of 5.15 Mt, while Amasya–Merzifon showcases the least storage capacity with 1.08 Mt. The storage capacities are also estimated based on the CO2 emissions from a typical 100 MW coal-fired powerplant as 10 years for Elazığ–Sivrice, 8 years for Çankırı, and 2 years for Amasya–Merzifon.
Citation Formats
S. M. H. T. Alvi, “EXPERIMENTAL INVESTIGATION OF CO2 ADSORPTION ON SELECT TURKISH LIGNITE COALS,” M.S. - Master of Science, Middle East Technical University, 2023.